Hydrogenated nitrile rubber

Abstract

Provided is a low ash-content hydrogenated nitrile rubber allowing excellent stability of a conductive material dispersion liquid and excellent capacity characteristics, cycle characteristics and high temperature storage characteristics of an electrochemical element containing the low ash-content hydrogenated nitrile rubber. More specifically, the hydrogenated nitrile rubber contains acrylonitrile polymerization units and 1,3-butadiene polymerization units, has a iodine value of 100 mg / 100 mg or less, and an ash content of 0.7 mass % or less.

Description

Hydrogenated nitrile rubber

[0001] The present invention relates to hydrogenated nitrile rubber, a method for producing the same, a bale of hydrogenated nitrile rubber, and electrode materials, electrode binders, conductive material dispersions, electrode slurries, electrodes, and electrochemical elements using hydrogenated nitrile rubber.

[0002] Electrochemical elements such as lithium-ion secondary batteries, lithium-ion capacitors, and electric double-layer capacitors are small, lightweight, have high energy density, and can be repeatedly charged and discharged, making them suitable for a wide range of applications. Therefore, in recent years, improvements to battery components such as electrodes have been considered to further enhance the performance of electrochemical elements.

[0003] Here, the electrodes used in electrochemical elements typically comprise a current collector and an electrode composite layer formed on the current collector. This electrode composite layer is formed, for example, by applying a slurry containing an electrode active material, a conductive material, and a binder onto the current collector and then drying the applied slurry.

[0004] Therefore, in recent years, attempts have been made to improve the binders used in forming electrode composite layers in order to achieve further performance improvements in electrochemical elements. For example, the use of hydrogenated nitrile rubber as a binder is being investigated.

[0005] For example, Patent Document 1 (WO2013 / 129658) discloses a lithium-ion secondary battery with excellent cycle characteristics, which contains a first polymer as a positive electrode active material, comprising polymerization units having nitrile groups, polymerization units having hydrophilic groups, (meth)acrylic acid ester polymerization units, and linear alkylene polymerization units having 4 or more carbon atoms, and a fluorine-containing polymer as a binder component. Specifically, the first polymer is obtained by (1) adding ion-exchanged water, sodium alkylbenzene sulfonate, acrylonitrile, butyl acrylate, methacrylic acid, 1,3-butadiene, and ammonium persulfate to an autoclave with a stirrer and carrying out emulsion polymerization at 40°C until the polymerization conversion rate reaches 85%, (2) adding palladium acetate to the obtained polymerization solution and carrying out a hydrogenation reaction twice at a hydrogen pressure of 3 MPa and 50°C for 6 hours, and then (3) coagulating with methanol, and (4) containing 20% ​​by mass of acrylonitrile polymerization units, 45% by mass of conjugated diene-derived polymerization units, 30% by mass of butyl acrylate polymerization units, and 5% by mass of methacrylic acid polymerization units, wherein the conjugated diene-derived polymerization units are formed from 38.8% by mass of hydrogenated linear alkylene structural units having 4 or more carbon atoms, 2.1% by mass of unhydrogenated butadiene polymerization units, and 4.1% by mass of 1,2-addition polymerization units, and obtaining hydrogenated NBR with an iodine value of 8 mg / 100 mg. In recent years, there has been a growing demand for further improvements in the dispersibility and stability of conductive material dispersions, as well as improvements in the flexibility of the manufactured electrodes, the capacitance characteristics, resistance characteristics, and high-temperature storage characteristics of electrochemical elements, and a reduction in the ash content of hydrogenated nitrile rubber.

[0006] Patent Document 2 (WO2022 / 163321) discloses a non-aqueous electrochemical element that exhibits excellent suppression of DC resistance increase at low temperatures and high-temperature storage properties, comprising polymer A containing nitrile group-containing monomer units and alkylene structural units, and a specific ester solvent and a non-halogenated carbonate solvent. Specifically, (1) an aqueous dispersion of a precursor (particulate polymer) of polymer A is obtained by charging an ion-exchanged water reactor with monomers such as acrylonitrile and 1,3-butadiene, sodium dodecylbenzenesulfonate as an emulsifier, and t-dodecyl mercaptan as a chain transfer agent, and then continuously adding cumene hydroperoxide as a polymerization initiator, a reducing agent, and a chelating agent to perform emulsion polymerization at 10°C until the polymerization conversion rate reaches 80%, and then (2) 1% acetic acid as a hydrogenation catalyst (3) Adding a palladium acetone solution, a hydrogenation reaction is carried out at a hydrogen pressure of 3 MPa and a temperature of 50°C for 6 hours. (4) NMP is added to the aqueous dispersion after the hydrogenation reaction as an organic solvent, and all water is removed under reduced pressure. (5) An 8% NMP solution of polymer A, consisting of 35% by mass of acrylonitrile, 65% by mass of butadiene, 18% by mass of hydrogenated 1,2-butadiene polymerization units, and a weight-average molecular weight of 150,000, is obtained. (6) Multilayer carbon nanotubes are added thereto to obtain a conductive material dispersion. On the other hand, there is a need to further improve the dispersibility and stability of the conductive material dispersion, and to improve the peel strength and warping characteristics of electrodes, the resistance characteristics, cycle characteristics and high-temperature storage characteristics of electrochemical elements, and there is also a need for lower ash content in hydrogenated nitrile rubber.

[0007] Patent Document 3 (WO2019 / 181869) discloses a conductive material dispersion with excellent dispersibility of carbon nanotubes, containing a binder containing a polymer containing carbon nanotubes, aromatic vinyl monomer units, and linear alkylene structural units having 4 or more carbon atoms, and a dispersion medium. Specifically, the polymer is prepared by (1) charging an ion-exchanged water reactor with an aqueous solution of sodium dodecylbenzenesulfonate as an emulsifier, styrene, acrylonitrile, methacrylic acid, 1,3-butadiene, and t-dodecyl mercaptan (2 parts) as a molecular weight modifier, and adding cumene hydroperoxide as a polymerization initiator while maintaining the temperature at 10°C, and emulsion polymerization until the conversion rate reaches 85% to obtain an aqueous dispersion of the precursor (particulate polymer). (2) Next, palladium acetate is added to the obtained aqueous dispersion of the precursor, and a hydrogenation reaction is carried out at a hydrogen pressure of 3 MPa and 50°C for 6 hours to produce a polymer with a styrene content of 33-48% by mass, acrylonitrile content of 10-21% by mass, conjugated diene (unhydrogenated) content of 4-6.5% by mass, linear alkylene structural units with 4 or more carbon atoms (conjugated diene hydrogenation content) of 22-43% by mass, a weight-average molecular weight (Mw) of 50,000 and an iodine value of 15-38. However, further improvements are desired, such as improved stability of the conductive material dispersion, improved peel strength and warping characteristics of electrodes, capacitance characteristics and cycle characteristics in electrochemical elements, and resistance increase during high-temperature storage. Furthermore, low ash content of hydrogenated nitrile rubber is also desired.

[0008] Patent Document 4 (WO2023 / 162835) discloses an electrochemical element composition that is excellent in terms of electrode flexibility and suppression of cracking of electrode active material, comprising a polymer containing a nitrile group-containing monomer unit, a conjugated diene monomer unit and / or alkylene structural unit, and having a functional group such as a carboxyl group, a trimethoxysilyl group, or a hydroxyl group at at least one terminal. Specifically, the polymer is prepared by (1) charging a reactor with ion-exchanged water, monomer components of 33 parts acrylonitrile and 67 parts 1,3-butadiene, potassium oleate as an emulsifier, and tert-dodecyl mercaptan (0.3 parts) as a molecular weight modifier, and carrying out emulsion polymerization at 5°C in the presence of potassium persulfate as a polymerization initiator until the polymerization conversion rate reaches 89%; (2) adding dibutylhydroxytoluene (BHT) as an antioxidant to the obtained polymerization solution, and then (3) adding a 25% by mass aqueous solution of calcium chloride while stirring to coagulate the polymer, washing it with 50 times the volume of ion-exchanged water, and then drying it under reduced pressure at 90°C to obtain a precursor (nitrile rubber) with a weight-average molecular weight of 210,000. Next, (4) the obtained precursor is dissolved in monochlorobenzene, and a Grubbs catalyst (bis(tricyclohexylphosphine)benzylideneruthenium chloride) is added to carry out a double decomposition reaction at 80°C and a stirring speed of 600 rpm. Then, (5) a Wilkinson catalyst and triphenylphosphine are added to carry out a hydrogenation reaction at 138°C and a hydrogen pressure of 8.4 MPa. (6) After activating carbon treatment to adjust the concentration of divalent or higher metal ions and remove residual chain transfer agents, the material is filtered and dried to obtain (7) hydrogenated nitrile rubber with a weight-average molecular weight of 48,000, an iodine value of 13, and a concentration of divalent or higher metal ions of 200 ppm or less. However, further improvement of the capacitance characteristics, cycle characteristics, and high-temperature storage characteristics of the electrochemical element, as well as a reduction in the ash content in the hydrogenated nitrile rubber, is desired.

[0009] On the other hand, as an example of low-ash hydrogenated nitrile rubber, Patent Document 5 (Japanese Patent Application Publication No. 2018-145434) discloses a low-ash hydrogenated nitrile rubber useful for sealing materials, hose materials, and transmission belts in the automotive field. Specifically, (1) acrylonitrile and 1,3-butadiene are charged, and polymerization auxiliary materials such as the sodium salt of a mixture of mono- and di-sulfonated naphthalene sulfonic acid having isobutylene oligomer substituents, the sodium salt of methylenebis(naphthalene sulfonate), tert-dodecyl mercaptan (0.66 to 0.88 in two separate additions), the potassium salt of coconut fatty acid, and potassium hydroxide are added, and potassium peroxodisulfate and tris(α-hydroxyethyl)amine are added as polymerization catalysts, and emulsion polymerization is carried out at 20°C until the polymerization conversion rate reaches 75%, and (2) 4-methyl-2,6-tert-butylphenol (BHT) is added to the obtained polymerization solution, and then an aqueous sodium chloride solution or magnesium chloride solution is prepared with tap water containing calcium ions. After adding a calcium aqueous solution and allowing it to solidify, (3) the mixture is washed at 60°C with tap water containing calcium ions, pre-dried with a welding screw to a residual moisture content of 15-25% by weight, and then vacuum-dried to obtain NBR with an acrylonitrile content of 38.6-38.8% by weight, a calcium content of 285-595 ppm, a chlorine content of 190-590 ppm, and a (calcium content / chlorine content) ratio of 0.95-1.87. Then, (4) the obtained NBR is dissolved in chlorobenzene and hydrogenated to a hydrogenation level of 99.4±0.2% with a rhodium-based catalyst. (5) After diluting the chlorobenzene-polymer solution to remove the rhodium, a 2% calcium chloride aqueous solution and a dilute sodium hydroxide aqueous solution are continuously added by metering to carry out a solidification reaction and obtain hydrogenated nitrile rubber. However, even when the hydrogenated nitrile rubber obtained here was used in the manufacture of electrochemical elements, it exhibited poor dispersibility in conductive material dispersions, resulting in inferior battery capacity characteristics, battery resistance characteristics, and cycle characteristics of the electrochemical elements. Furthermore, it experienced an increase in resistance during high-temperature storage, making it unsuitable as an electrode binder for lithium-ion secondary batteries.

[0010] Furthermore, Patent Document 6 (WO2007 / 049651) discloses a carboxyl group-containing nitrile rubber that provides crosslinked structures with low compression set and dynamic heat generation, and exhibits excellent processability, as a material for rubber products for industrial and automotive use. This rubber has an α,β-ethylenically unsaturated nitrile monomer unit content of 10 to 60% by mass, an iodine value of 120 or less, and a total amount of magnesium, calcium, and aluminum of 2000 ppm or less. Specifically, (1) acrylonitrile, mono-n-butyl fumarate, butadiene, sodium dodecylbenzenesulfonate, t-dodecyl mercaptan (0.5 parts), and cumene hydroperoxide are added and emulsion polymerization is carried out at 5°C for 16 hours. Then (2) a palladium catalyst is added to the obtained polymerization solution to perform a hydrogenation reaction. A magnesium sulfate aqueous solution (pH 4) is added to the latex of the nitrile group-containing saturated copolymer rubber to perform a coagulation reaction. (3) After coagulation, the crumb is filtered and washed with water three times, then subjected to a centrifuge to remove the magnesium sulfate aqueous solution contained in the rubber, and vacuum dried at 60°C for 12 hours. (4) A nitrile rubber is obtained with an acrylonitrile polymerization unit content of 34%, an iodine value of 9, an ML viscosity of 85, a magnesium content of 1-2 ppm, a calcium content of 1 ppm, and an aluminum content of 1 ppm or less. However, even when attempting to use the nitrile rubber obtained here for the manufacture of electrochemical elements, it was inferior in terms of the dispersibility and stability of the conductive material dispersion, the peel strength at the electrodes, and the battery capacity characteristics, battery resistance characteristics, and cycle characteristics of the electrochemical element. Furthermore, it exhibited an increase in resistance during high-temperature storage, making it unsuitable as an electrode binder for lithium-ion secondary batteries.

[0011] Furthermore, Patent Document 7 (Japanese Patent Application Publication No. 2009-179686) discloses a method in which (1) carboxyl group-containing nitrile rubber (34% by weight of acrylonitrile monomer units, 59% by weight of butadiene monomer units, 7% by weight of n-monobutyl maleate monomer units, iodine value 10, solid content concentration 10.8% by weight) obtained by emulsion polymerization in accordance with the method described in Patent Document 5, and (2) a 5% by weight aqueous solution of magnesium sulfate as a coagulation solution are prepared, and (3) coagulation, washing, dewatering and drying are continuously performed using a screw-type extruder with a total length L = 3005 mm, outer diameter Da = 48 mm, L / Da = 63, and sheet-like dried carboxyl group-containing nitrile rubber is recovered from the downstream die. However, this method was not suitable for use as an electrode binder in lithium-ion secondary batteries.

[0012] Furthermore, Patent Document 8 (WO2020 / 138183) states that (1) an ion-exchanged water, 10% by weight sodium dodecylbenzenesulfonate, sodium salt of naphthalene sulfonic acid formalin condensate, acrylonitrile, mono-n-butyl maleate, n-butyl acrylate, t-dodecyl mercaptan, 1,3-butadiene, and cumene hydroperoxide are charged into a metal bottle, and emulsion polymerization is carried out at 10°C until the polymerization conversion rate reaches 80% to obtain nitrile rubber latex, and then ( 2) A palladium chloride aqueous solution adjusted to pH 12 is added, and a hydrogenation reaction is carried out at a hydrogen pressure of 3 MPa and a temperature of 50°C for 6 hours. (3) An appropriate amount of antioxidant is added, and the pH of the hydrogenated nitrile rubber latex is adjusted to 3.6 using a sulfuric acid aqueous solution. (4) Using a 25% by weight sodium chloride aqueous solution and steam as a coagulation solution, coagulation, washing, dewatering, and drying are carried out using a screw-type extruder to obtain hydrogenated nitrile rubber with a chlorine content of 711 to 1112 ppm and a sodium content of 461 to 721 ppm. However, the hydrogenated nitrile rubber obtained here was not suitable as an electrode binder in lithium-ion secondary batteries.

[0013] Publication No. WO2013 / 129658, Publication No. WO2022 / 163321, Publication No. WO2019 / 181869, Publication No. WO2023 / 162835, Japanese Patent Publication No. 2018-145434, Publication No. WO2007 / 049651, Japanese Patent Publication No. 2009-179686, Japanese Patent Publication No. WO2020 / 138183

[0014] This invention has been made in view of the above circumstances, and aims to provide a low-ash hydrogenated nitrile rubber that has excellent stability in conductive material dispersions and excellent capacitance characteristics, cycle characteristics, and high-temperature storage characteristics of electrochemical elements, as well as a method for producing the same, a bale of hydrogenated nitrile rubber, and an electrode material, electrode binder, conductive material dispersion, electrode slurry, electrode, and electrochemical element using hydrogenated nitrile rubber.

[0015] In view of the above problems, the present inventors conducted intensive research and found that a hydrogenated nitrile rubber containing acrylonitrile polymerization units and 1,3-butadiene polymerization units, with a reduced iodine value and ash content, is effective in solving the above problems.

[0016] The inventors have found that a hydrogenated nitrile rubber containing acrylonitrile polymerization units and 1,3-butadiene polymerization units, within a specific weight-average molecular weight (Mw) range, with a low iodine value to increase bulk density, and reduced ash content of specific ash components, can improve the dispersibility and stability of conductive material dispersions in the manufacture of electrochemical elements, thereby enhancing the cycle characteristics and high-temperature storage characteristics of electrochemical elements.

[0017] The inventors have also found that a hydrogenated nitrile rubber containing acrylonitrile polymerization units and 1,3-butadiene polymerization units, having a specific weight-average molecular weight (Mw) and a specific ratio of Z-average molecular weight (Mz) to weight-average molecular weight (Mw) (Mz / Mw), having a low iodine value, high bulk density, and reduced ash content of a specific ash component, can improve the dispersibility and stability of conductive material dispersions in the manufacture of electrochemical elements, and significantly enhance the capacitance characteristics, resistance characteristics, cycle characteristics, and high-temperature storage characteristics of electrochemical elements.

[0018] The inventors have also found that a hydrogenated nitrile rubber containing acrylonitrile polymerization units and 1,3-butadiene polymerization units, with a reduced iodine value and increased bulk density, containing an antioxidant, and with reduced ash content of specific ash components, can improve the stability of conductive material dispersions, increase the peel strength of electrodes, and significantly enhance the capacitance characteristics, cycle characteristics, and high-temperature storage characteristics of electrochemical elements in the manufacture of electrochemical elements.

[0019] The inventors have discovered that by reducing the iodine value of hydrogenated nitrile rubber and increasing its bulk density, the stability of conductive material dispersions can be significantly improved, thereby enhancing the cycle characteristics of electrochemical elements. They found that increasing the bulk density of hydrogenated nitrile rubber can be achieved by baling the crumb-like hydrogenated nitrile rubber under pressure using a bailer, or by extruding the hydrogenated nitrile rubber into a sheet using a screw-type twin-screw extruder and then laminating the sheet-like hydrogenated nitrile rubber. Furthermore, they discovered that by using a screw-type twin-screw extruder equipped with a reduced-pressure drying section to remove the air contained within the hydrogenated nitrile rubber, and then laminating the sheet-like dried rubber by extrusion, a hydrogenated nitrile rubber bale with an overwhelmingly high bulk density (low oxygen content) can be produced.

[0020] The inventors have found that by specifying the Mw and Mz / Mw of hydrogenated nitrile rubber, the dispersibility of conductive material dispersions, the peel strength of electrodes, and the resistance characteristics of electrochemical elements can be greatly improved and these characteristics can be highly balanced. In particular, the inventors have found that the peel strength of electrodes can be greatly improved by increasing the Mz / Mw of hydrogenated nitrile rubber, and that nitrile rubber with a large Mz / Mw is required because the Mz / Mw of the precursor nitrile rubber decreases in the double decomposition reaction and hydrogenation reaction, and that these can be obtained by adjusting the polymerization temperature and polymerization conversion rate in the emulsion polymerization of nitrile rubber.

[0021] The inventors have found that by more precisely specifying the Mw of the hydrogenated nitrile rubber, the dispersibility of the conductive material dispersion, the peel strength of the electrode, and the resistance characteristics of the electrochemical element can be greatly improved, and these characteristics can be highly balanced.

[0022] The inventors have discovered that hydrogenated nitrile rubber with a low iodine value and low ash content enhances the stability of conductive material dispersions, significantly improving the capacitance characteristics, cycle characteristics, and high-temperature storage characteristics of electrochemical elements.

[0023] The inventors have discovered that low-ash hydrogenated nitrile rubber containing an anti-aging agent and having reduced ash content can improve the stability of conductive material dispersions, increase the peel strength of electrodes, and significantly enhance the capacitance characteristics and high-temperature storage characteristics of electrochemical elements.

[0024] The inventors have found that the effectiveness of the antioxidant in hydrogenated nitrile rubber can be significantly improved by adding the antioxidant to the polymerization solution after emulsion polymerization of nitrile rubber before hydrogenation, rather than by adding the antioxidant to hydrogenated nitrile rubber. Furthermore, the inventors have found that the antioxidant content of the nitrile rubber is almost entirely inherited by the hydrogenated nitrile rubber after hydrogenation, and that the effectiveness of the antioxidant can be further improved by melt-kneading and drying the hydrated crumb produced by hydrogenating and solidifying the nitrile rubber containing the antioxidant using a screw-type twin-screw extruder.

[0025] The present inventors have found that in the production of low-ash hydrogenated nitrile rubber, (1) in the cement state where the hydrogenation reaction is carried out in an organic solvent reaction solution such as monochlorobenzene, it is possible to remove catalyst components dissolved in the organic solvent using ion exchange resins or activated carbon, but it is difficult to remove salt compounds that are insoluble in organic solvents and have high calcium and sulfur content; (2) the low molecular weight hydrogenated nitrile rubber produced by hydrogenation after double decomposition of nitrile rubber becomes viscous and ash removal is difficult; and (3) most of the ash in hydrogenated nitrile rubber is auxiliary material used in the polymerization and solidification reactions during the production of nitrile rubber, and therefore, if low-ash nitrile rubber is produced, low-ash hydrogenated nitrile rubber can be easily produced.

[0026] The inventors have found that while the ash content in nitrile rubber can be reduced to some extent by known methods, further reduction becomes difficult once the ash content falls below 1% by mass. However, they have discovered that by adding the emulsion polymerized polymer to a rapidly rotating solidifying liquid during the solidification reaction after emulsion polymerization, particularly by adding the emulsion polymerized polymer directly to the rapidly rotating central stirring blade, the resulting water-containing crumbs facilitate the removal of ash during washing and dewatering processes at specific temperatures. In particular, dewatering to a water content of 35% by mass or less significantly reduces the ash content in the nitrile rubber. Furthermore, the inventors have found that the water-containing crumbs produced by the above-mentioned specific solidification method have a specific particle size distribution, a complex shape, and often a large hollow structure in the center. This significantly improves washing and dewatering efficiency (ash removal from the crumbs), enabling the production of low-ash nitrile rubber.

[0027] The inventors also found that differences in the ash content of nitrile rubber have different effects on the performance of hydrogenated nitrile rubber when used in the manufacture of electrochemical elements.

[0028] We found that ash high in sodium and potassium cannot be removed by ordinary washing alone because it is inherent in the water-containing crumb produced during solidification, as many sodium and potassium salts are used as polymerization auxiliary materials. It remains in the nitrile rubber and also in hydrogenated nitrile rubber, and when used in the manufacture of electrochemical elements, it destroys the negative electrode active material and significantly reduces the capacitance characteristics of the electrochemical element.

[0029] We found that ash rich in calcium and sulfur remains until the end when the water-containing crumb with the above-mentioned special shape and particle size distribution is washed with hot water or dehydrated with a squeezer, but it has almost no effect on reducing the capacitance characteristics of the electrochemical element, and its effect on worsening high-temperature storage is smaller than that of ash rich in sodium and potassium, and moreover, it has the property of strengthening the peel strength of the electrode.

[0030] The inventors have also found that differences in the total ratio of calcium to sulfur, the total ratio of sodium to potassium, the mass ratio of calcium to sulfur, the mass ratio of calcium to chlorine, the mass ratio of sulfur to chlorine, and the mass ratio of the total amount of sodium and potassium to the total amount of calcium and sulfur in the ash content of hydrogenated nitrile rubber have different effects on the peel strength of electrodes, the capacitance characteristics of electrochemical elements, and the high-temperature storage characteristics. Furthermore, the inventors have found that when alkali metal salts such as sodium and potassium, sulfates, or sulfonates are used as polymerization auxiliary materials, the amount of ash remaining in the hydrogenated nitrile rubber differs, affecting the various characteristics of the electrochemical elements.

[0031] The inventors have further discovered that by specifying the proportion of acrylonitrile polymerization units, the proportion of 1,2- units in 1,3-butadiene polymerization units, the antioxidant content, particle size distribution (D90 / D10 and D50 / D10), polymer pH, water content, and the proportions of sodium and potassium, calcium and sulfur, rhodium and ruthenium, and phosphorus in the ash, the mass ratio of the total amount of sodium and potassium to the total amount of calcium and sulfur, the mass ratio of calcium to chlorine, the mass ratio of calcium to sulfur, and the mass ratio of sulfur to chlorine, the dispersibility and stability of the conductive material dispersion, the peel strength of the electrode, and the capacitance characteristics, resistance characteristics, cycle characteristics, and high-temperature storage characteristics of the electrochemical element, the inventors have found that these can be further improved.

[0032] Based on these findings, the inventors have completed the present invention.

[0033] According to one aspect of the present invention, the following [1] to

[43] are provided.

[0034] [1] Hydrogenated nitrile rubber containing acrylonitrile polymerization units and 1,3-butadiene polymerization units, having an iodine value of 100 mg / 100 mg or less and an ash content of 0.7% by mass or less.

[0035] [2] The weight-average molecular weight (Mw) is in the range of 10,000 to 5,000,000, the ratio of Z-average molecular weight (Mz) to weight-average molecular weight (Mw) (Mz / Mw) is 1.5 or more, and the bulk density is 0.7 g / cm³. ３The hydrogenated nitrile rubber according to [1], wherein the ratio of the total amount (Ca + S) of calcium content (Ca) and sulfur content (S) in the ash is 40% by mass or more.

[0036] [3] Weight-average molecular weight (Mw) is in the range of 10,000 to 2,500,000, and bulk density is 0.7 g / cm³. ３ The hydrogenated nitrile rubber according to [1], wherein the ratio of the total amount (Ca + S) of calcium content (Ca) and sulfur content (S) in the ash is 40% by mass or more.

[0037] [4] Weight-average molecular weight (Mw) is in the range of 10,000 to 2,500,000, and bulk density is 0.7 g / cm³. ３ The hydrogenated nitrile rubber according to [1], wherein the mass ratio ((Na+K) / (Ca+S)) of the total amount of sodium content (Na) and potassium content (K) in the ash (Na+K) to the total amount of calcium content (Ca) and sulfur content (S) (Ca+S) is 0.5 or less.

[0038] [5] Weight-average molecular weight (Mw) is in the range of 10,000 to 2,500,000, and bulk density is 0.7 g / cm³. ３ The hydrogenated nitrile rubber according to [1], wherein the mass ratio (Ca / Cl) of calcium content (Ca) to chlorine content (Cl) in the ash is 1 or more, and the mass ratio (S / Cl) of sulfur content (S) to chlorine content (Cl) is 1 or more.

[0039] [6] Contains an anti-aging agent and has a bulk density of 0.7 g / cm³ ３ The hydrogenated nitrile rubber according to [1], wherein the ratio of the total amount (Ca + S) of calcium content (Ca) and sulfur content (S) in the ash is 40% by mass or more.

[0040] [7] The hydrogenated nitrile rubber according to [1] or [6], wherein the weight-average molecular weight (Mw) is in the range of 10,000 to 5,000,000.

[0041] [8] The hydrogenated nitrile rubber according to any one of [1] to [3], [6] and [7], wherein the ratio of the total amount (Ca + S) of calcium content (Ca) and sulfur content (S) in the ash is 50% by mass or more.

[0042] [9] The hydrogenated nitrile rubber according to [4] or [5], wherein the ratio of the total amount (Ca + S) of calcium content (Ca) and sulfur content (S) in the ash is 30% by mass or more.

[0043]

[10] Hydrogenated nitrile rubber according to any one of [1] to [9], wherein the total proportion of acrylonitrile polymerization units and 1,3-butadiene polymerization units is 70 to 100% by mass.

[0044]

[11] Hydrogenated nitrile rubber according to any one of [1] to

[10] , wherein the acrylonitrile polymerization units are 28% by mass or more and 40% by mass or less.

[0045]

[12] The hydrogenated nitrile rubber according to any one of [1] to

[11] , wherein the total proportion of 1,2-bonding units and their hydride units in the 1,3-butadiene polymerization unit is 30% by mass or less.

[0046]

[13] The hydrogenated nitrile rubber according to any one of [1] to

[12] , wherein the total proportion of 1,2-bonding units and their hydride units in the 1,3-butadiene polymerization unit is 5% by mass or more.

[0047]

[14] The hydrogenated nitrile rubber according to any one of [1] to

[13] , wherein the total proportion of 1,2-bonding units and their hydride units in the 1,3-butadiene polymerization unit is 10% by mass or more and 20% by mass or less.

[0048]

[15] Hydrogenated nitrile rubber according to any one of [1] to

[14] , wherein the content of the anti-aging agent is in the range of 0.001 to 2% by mass.

[0049]

[16] Hydrogenated nitrile rubber according to any one of [1] to

[15] , wherein the polymer pH is in the range of 4.5 to 6.

[0050]

[17] The hydrogenated nitrile rubber according to any one of [1] to

[16] , wherein the ratio (D90 / D10) of the particle size when 90% of the total volume is present to the particle size when 10% of the total volume is present is 150 or less.

[0051]

[18] The hydrogenated nitrile rubber according to any one of [1] to

[17] , wherein the ash content is 0.01% by mass or more.

[0052]

[19] The hydrogenated nitrile rubber according to any one of [1] to

[18] , wherein the ratio of the total amount (Na + K) of sodium content (Na) and potassium content (K) in the ash is 20% by mass or less.

[0053]

[20] The hydrogenated nitrile rubber according to any one of [1] to

[19] , wherein the mass ratio (Ca / Cl) of the calcium content (Ca) to the chlorine content (Cl) in the ash is 1 or more.

[0054]

[21] The hydrogenated nitrile rubber according to any one of [1] to

[20] , wherein the mass ratio (Ca / Cl) of calcium content (Ca) to chlorine content (Cl) in the ash is 1.5 or more.

[0055]

[22] The hydrogenated nitrile rubber according to any one of [1] to

[21] , wherein the mass ratio (S / Cl) of the sulfur content (S) to the chlorine content (Cl) in the ash is 1 or more.

[0056]

[23] The hydrogenated nitrile rubber according to any one of [1] to

[22] , wherein the mass ratio (S / Cl) of the sulfur content (S) to the chlorine content (Cl) in the ash is 1.5 or more.

[0057]

[24] The hydrogenated nitrile rubber according to any one of [1] to

[23] , wherein the mass ratio (Ca / S) of the calcium content (Ca) to the sulfur content (S) in the ash is 3.5 or less.

[0058]

[25] The hydrogenated nitrile rubber according to any one of [1] to

[24] , wherein the mass ratio ((Na+K) / (Ca+S)) of the total amount of sodium content (Na) and potassium content (K) in the ash (Na+K) to the total amount of calcium content (Ca) and sulfur content (S) (Ca+S) is 0.5 or less.

[0059]

[26] The hydrogenated nitrile rubber according to any one of [1] to

[25] , wherein the content (M) of the metal used in the hydrogenation catalyst in the ash is 1% by mass or less.

[0060]

[27] The hydrogenated nitrile rubber according to any one of [1] to

[26] , wherein the ratio of the total amount (Rh + Ru) of rhodium content (Rh) and ruthenium content (Ru) in the ash is 1% by mass or less.

[0061]

[28] The hydrogenated nitrile rubber according to any one of [1] to

[27] , wherein the phosphorus content (P) ratio in the ash is 10% by mass or less.

[0062]

[29] Hydrogenated nitrile rubber according to any one of [1] to

[28] , wherein the ratio of the Z-average molecular weight (Mz) to the weight-average molecular weight (Mw) (Mz / Mw) is 1.5 or more.

[0063]

[30] A hydrogenated nitrile rubber according to any of [1] to

[29] , wherein the weight-average molecular weight (NMP-Mw) measured with N-methylpyrrolidone (NMP) and the weight-average molecular weight (THF-Mw) measured with tetrahydrofuran (THF) are in the relationship NMP-Mw ≥ THF-Mw.

[0064]

[31] Hydrogenated nitrile rubber according to any one of [1] to

[30] , wherein the water content is less than 1% by mass.

[0065]

[32] Hydrogenated nitrile rubber according to any one of [1] to

[31] , wherein a polymer obtained by emulsion polymerization of acrylonitrile and 1,3-butadiene and coagulation with calcium chloride is hydrogenated.

[0066]

[33] Hydrogenated nitrile rubber according to any one of [1] to

[32] , wherein a polymer obtained by emulsion polymerization of acrylonitrile and 1,3-butadiene using an alkali metal salt as a polymerization auxiliary material is hydrogenated.

[0067]

[34] Hydrogenated nitrile rubber according to any one of [1] to

[33] , wherein a polymer obtained by emulsion polymerization of acrylonitrile and 1,3-butadiene using sulfate and / or sulfonate as polymerization auxiliary material is hydrogenated.

[0068]

[35] Hydrogenated nitrile rubber according to any one of [1] to

[34] , wherein at least one salt compound selected from the group consisting of alkali metal salts, sulfates, and sulfonates is used as a polymerization auxiliary material, and a polymer obtained by emulsion polymerization of acrylonitrile and 1,3-butadiene and coagulation with calcium chloride is hydrogenated.

[0069]

[36] A method for producing hydrogenated nitrile rubber according to any one of [1] to

[35] , comprising: an emulsion polymerization step of emulsion polymerization of monomer components containing acrylonitrile and 1,3-butadiene to obtain an emulsion polymerization liquid; an antioxidant addition step of adding an antioxidant to the obtained emulsion polymerization liquid; a coagulation step of adding the emulsion polymerization liquid to which the antioxidant has been added to a coagulation liquid that is being vigorously stirred to produce a water-containing crumb; a washing step of washing the produced water-containing crumb; a dehydration step of dehydrating the washed water-containing crumb to a water content of 35% by mass or less; a drying step of drying the polymer after dehydration; a hydrogenation step of dissolving the dried polymer in an organic solvent and carrying out a hydrogenation reaction; and a hydrogenated polymer dehydration and drying step of coagulating the reaction liquid after the hydrogenation reaction and dehydrating and drying the produced water-containing crumb using a screw-type twin-screw extruder to extrude dried rubber.

[0070] A hydrogenated nitrile rubber bale obtained by bailing the hydrogenated nitrile rubber described in any of

[37] [1] to

[35] .

[0071] An electrode material comprising hydrogenated nitrile rubber as described in any of

[38] [1] to

[35] .

[0072] An electrode binder obtained by dissolving the hydrogenated nitrile rubber described in any of

[39] [1] to

[35] in N-methylpyrrolidone (NMP).

[0073] A conductive material dispersion obtained by dissolving or dispersing the hydrogenated nitrile rubber and conductive material described in any of

[40] [1] to

[35] in N-methylpyrrolidone (NMP).

[0074]

[41] An electrode slurry obtained by dissolving or dispersing an electrode active material, a conductive material, and the hydrogenated nitrile rubber described in any of [1] to

[35] in N-methylpyrrolidone (NMP).

[0075] An electrode comprising hydrogenated nitrile rubber as described in any of

[42] [1] to

[35] .

[0076] An electrochemical element comprising hydrogenated nitrile rubber as described in any of

[43] [1] to

[35] .

[0077] The present invention provides a hydrogenated nitrile rubber that can improve the stability of conductive material dispersions and enhance the capacitance characteristics, cycle characteristics, and high-temperature storage characteristics of electrochemical elements, a hydrogenated nitrile rubber bale formed from hydrogenated nitrile rubber, and an electrode material, electrode binder, conductive material dispersion, electrode slurry, electrode, and electrochemical element using hydrogenated nitrile rubber.

[0078] This figure shows an example of a nitrile rubber manufacturing system according to an embodiment of the present invention. This figure shows an example of the upstream section of a hydrogenated nitrile rubber manufacturing system according to an embodiment of the present invention. This figure shows an example of the downstream section of a hydrogenated nitrile rubber manufacturing system according to an embodiment of the present invention.

[0079] Embodiments of the present invention will be described in detail below. In the following description, the positive electrode will be described as an example of an electrode according to the present invention.

[0080] <Hydrogenated Nitrile Rubber> The hydrogenated nitrile rubber of the present invention contains acrylonitrile polymerization units and 1,3-butadiene polymerization units, and is characterized by having a low iodine value and reduced ash content.

[0081] One embodiment of the hydrogenated nitrile rubber of the present invention comprises acrylonitrile polymerization units and 1,3-butadiene polymerization units, has an iodine value of 100 mg / 100 mg or less, a weight-average molecular weight (Mw) in the range of 10,000 to 2,500,000, and a bulk density of 0.7 g / cm³. ３ The above characteristics include having an ash content of 0.7% by mass or less, and a total amount of calcium (Ca) and sulfur (S) in the ash (Ca + S) of 40% by mass or more.

[0082] Another aspect of the hydrogenated nitrile rubber of the present invention includes acrylonitrile polymerized units and 1,3-butadiene polymerized units, has an iodine value of 100 mg / 100 mg or less, a weight average molecular weight (Mw) in the range of 10,000 or more and 2,500,000 or less, and a bulk specific gravity of 0.7 g / cm ３ or more, an ash content of 0.7% by mass or less, and is characterized in that the mass ratio ((Na+K) / (Ca+S)) of the total amount (Na+K) of sodium content (Na) and potassium content (K) to the total amount (Ca+S) of calcium content (Ca) and sulfur content (S) in the ash is 0.5 or less.

[0083] Another aspect of the hydrogenated nitrile rubber of the present invention includes acrylonitrile polymerized units and 1,3-butadiene polymerized units, has an iodine value of 100 mg / 100 mg or less, a weight average molecular weight (Mw) in the range of 10,000 or more and 2,500,000 or less, and a bulk specific gravity of 0.7 g / cm ３ or more, an ash content of 0.7% by mass or less, and is characterized in that the mass ratio (Ca / Cl) of calcium content (Ca) to chlorine content (Cl) in the ash is 1 or more, and the mass ratio (S / Cl) of sulfur content (S) to chlorine content (Cl) is 1 or more.

[0084] Another aspect of the hydrogenated nitrile rubber of the present invention includes acrylonitrile polymerized units and 1,3-butadiene polymerized units, has a weight average molecular weight (Mw) in the range of 10,000 or more and 5,000,000 or less, a ratio of Z-average molecular weight (Mz) to weight average molecular weight (Mw) (Mz / Mw) of 1.5 or more, an iodine value of 100 mg / 100 mg or less, and a bulk specific gravity of 0.7 g / cm ３ or more, an ash content of 0.7% by mass or less, and is characterized in that the proportion of the total amount (Ca+S) of calcium content (Ca) and sulfur content (S) in the ash is 40% by mass or more.

[0085] Another aspect of the hydrogenated nitrile rubber of the present invention includes acrylonitrile polymerized units and 1,3-butadiene polymerized units, has an iodine value of 100 mg / 100 mg or less, contains an anti-aging agent, and has a bulk specific gravity of 0.7 g / cm ３The above characteristics include having an ash content of 0.7% by mass or less, and a total amount of calcium (Ca) and sulfur (S) in the ash (Ca + S) of 40% by mass or more.

[0086] (Repeating Units) The hydrogenated nitrile rubber of the present invention contains acrylonitrile polymerization units and 1,3-butadiene polymerization units, and the 1,3-butadiene polymerization units consist of 1,2-bonding units, 1,4-bonding units and their hydride units. Such hydrogenated nitrile rubber is a component that can function as a binder in an electrode composite layer formed in an electrochemical element, holding electrode active materials and the like from the current collector without detaching them. Furthermore, such hydrogenated nitrile rubber can also function as a dispersant in a conductive material dispersion containing a conductive material, capable of dispersing the conductive material.

[0087] The proportion of acrylonitrile polymerization units in the hydrogenated nitrile rubber of the present invention is not particularly limited, but is usually 10% by mass or more, preferably 20% by mass or more, more preferably 25% by mass or more, even more preferably 28% by mass or more, most preferably 30% by mass or more, and usually 60% by mass or less, preferably 55% by mass or less, more preferably 50% by mass or less, even more preferably 45% by mass or less, and most preferably 40% by mass or less. When the acrylonitrile polymerization units in the hydrogenated nitrile rubber are within this range, it is preferable because it improves the dispersibility of the conductive material dispersion and enhances the cycle characteristics of the electrochemical element.

[0088] The proportion of 1,3-butadiene polymerization units in the hydrogenated nitrile rubber of the present invention is not particularly limited, but is usually 40% by mass or more, preferably 45% by mass or more, more preferably 50% by mass or more, even more preferably 55% by mass or more, most preferably 60% by mass or more, and usually 90% by mass or less, preferably 85% by mass or less, more preferably 80% by mass or less, even more preferably 75% by mass or less, most preferably 70% by mass or less. The 1,3-butadiene polymerization units in the hydrogenated nitrile rubber refer to the total number of unhydrogenated and hydrogenated units of 1,3-butadiene polymerization units, that is, the total number of 1,2-bonding units, 1,4-bonding units and their hydride units.

[0089] The total ratio of acrylonitrile polymerization units and 1,3-butadiene polymerization units in the hydrogenated nitrile rubber of the present invention is not particularly limited, but is usually in the range of 70 to 100% by mass, preferably 80 to 100% by mass, more preferably 90 to 100% by mass, even more preferably 95 to 100% by mass, and most preferably 97 to 100% by mass.

[0090] The total ratio of 1,2-bonding units and their hydride units in the 1,3-butadiene polymerization unit of the hydrogenated nitrile rubber of the present invention is not particularly limited, but is usually 1% by mass or more, preferably 3% by mass or more, more preferably 5% by mass or more, or preferably in the order of 7% by mass or more, 8% by mass or more, 9% by mass or more, 9.5% by mass or more, 10% by mass or more, 10.5% by mass or more, 11% by mass or more, 11.5% by mass or more, 12% by mass or more, 12.5% ​​by mass or more, and 13% by mass or more. When the ratio is within this range, the warpage characteristics of the electrode and the capacitance characteristics of the electrochemical element can be greatly improved.

[0091] The upper limit of the total ratio of 1,2-bonding units and their hydride units in the 1,3-butadiene polymerization unit of the hydrogenated nitrile rubber of the present invention is not particularly limited, but is usually 50% by mass or less, preferably 45% by mass or less, more preferably 40% by mass or less, or preferably in the order of 35% by mass or less, 30% by mass or less, 25% by mass or less, 20% by mass or less, 19% by mass or less, 18% by mass or less, 17% by mass or less, 16% by mass or less, and 15% by mass or less, which can increase the flexibility of the manufactured electrode. The ratio of 1,2-bonding units and their hydride units in the 1,3-butadiene polymerization unit is not particularly limited and can be appropriately adjusted based on the iodine value of the hydrogenated nitrile rubber.

[0092] The hydrogenated nitrile rubber of the present invention may contain, as necessary, other repeating units in addition to the acrylonitrile polymerization units and 1,3-butadiene polymerization units described above. There are no particular limitations on the other repeating units, but for example, polar group-containing monomer units are preferably used.

[0093] There are no particular limitations on the polar group of the polar group-containing monomer unit, but examples include epoxy groups, acetoacetoxyalkyl groups, diester dicarboxylic acid groups, and acidic groups, with acidic groups being preferred.

[0094] Examples of epoxy group-containing monomers that can form epoxy group-containing monomer units include glycidyl methacrylate and glycidyl acrylate, with glycidyl methacrylate being preferred. Examples of acetoacetoxyalkyl group-containing monomers include acetoacetoxyethyl methacrylate. Examples of diester dicarboxylic acid group-containing monomers include dibutyl maleate.

[0095] Examples of acidic group-containing monomers that can form acidic group-containing monomer units include carboxylic acid group-containing monomers, sulfonic acid group-containing monomers, and phosphate group-containing monomers, among which carboxylic acid group-containing monomers are preferred.

[0096] Examples of monomers containing a carboxylic acid group include monocarboxylic acids, dicarboxylic acids and their acid anhydrides, with monocarboxylic acids being preferred. Examples of monocarboxylic acids include acrylic acid, methacrylic acid, crotonic acid, monobutyl maleate, and monododecyl maleate, with methacrylic acid, acrylic acid, and monobutyl maleate being preferred, and methacrylic acid being more preferred. Examples of dicarboxylic acids include maleic acid, fumaric acid, itaconic acid, methylmaleic acid, dimethylmaleic acid, phenylmaleic acid, chloromaleic acid, dichloromaleic acid, and fluoromaleic acid.

[0097] Examples of monomers containing sulfonic acid groups include vinyl sulfonic acid, methyl vinyl sulfonic acid, (meth)allyl sulfonic acid, styrene sulfonic acid, ethyl 2-meth)acrylate, 2-acrylamido-2-methylpropanesulfonic acid, and 3-alyloxy-2-hydroxypropanesulfonic acid. Examples of monomers containing phosphate groups include 2-(meth)acryloyloxyethyl phosphate, methyl 2-(meth)acryloyloxyethyl phosphate, and ethyl-(meth)acryloyloxyethyl phosphate.

[0098] These other repeating units can be used individually or in combination of two or more types. There are no particular limitations on the content of these other repeating units in the hydrogenated nitrile rubber, but it is usually 30% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, and most preferably 3% by mass or less.

[0099] (Anti-aging agent) The hydrogenated nitrile rubber of the present invention may contain an anti-aging agent as needed. Including an anti-aging agent in the hydrogenated nitrile rubber is preferable because it greatly enhances the stability of the conductive material dispersion and the peel strength of the electrodes in the manufacture of electrochemical elements.

[0100] There are no particular limitations on the type of antioxidant that can be included, but examples include amine-based antioxidants and phenol-based antioxidants, with phenol-based antioxidants being preferred. There are no particular limitations on the type of phenol-based antioxidant, but hindered phenol-based antioxidants are particularly preferred, as they can improve the stability of the conductive material dispersion and enhance the electrode peel strength.

[0101] Examples of hindered phenol-based antioxidants include 2,6-di-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-pentenyl-4-methylphenol, 2,2-methylenebis(4-methyl-6-t-butylphenol), 2,4-bis(octylthiomethyl)-6-methylphenol, 2,6-di-t-butyl-α-dimethylamino-p-cresol, and 3-(4-hydroxy-3,5 3-(4-hydroxy-3,5-di-t-butylphenyl) butyl propionate, 3-(4-hydroxy-3,5-di-t-butylphenyl) hexyl propionate, 3-(4-hydroxy-3,5-di-t-butylphenyl) octyl propionate, 3-(4-hydroxy-3,5-di-t-butylphenyl) decyl propionate, 3-(4-hydroxy-3,5-di-t-butylphenyl) dodecyl propionate, 3-(4-hydroxy-3,5-di-t-butylphenyl) butyl propionate Examples include octadecyl 3-(4-hydroxy-3,5-diisopropylphenyl)propionate, heptyl 3-(4-hydroxy-3,5-diisopropylphenyl)propionate, octyl 3-(4-hydroxy-3,5-diisopropylphenyl)propionate, dodecyl 3-(4-hydroxy-3,5-diisopropylphenyl)propionate, octadecyl 3-(4-hydroxy-3,5-diisopropylphenyl)propionate, 4,4'-methylenebis(2,6-dibutylphenol), 2,6-di-t-butyl-4-(4,6-bis(octylthio)-1,3,5-triazine-2-ylamino)phenol, and preferably 2,6-di-t-butyl-4-methylphenol (dibutylhydroxytoluene = BHT), 2,2-methylenebis(4-methyl-6-t-butylphenol), and 2,4-bis(octylthiomethyl)-6-methylphenol, with BHT being the most preferred.

[0102] Examples of phenolic antioxidants other than hindered phenolic antioxidants include styrene phenol, butylhydroxyanisole, styrene phenols such as mono(or di, or tri)(α-methylbenzyl)phenol, 2,2'-methylene-bis(4-methyl-6-t-butylphenol), alkylated bisphenol, 2,4-bis[(octylthio)methyl]-6-methylphenol, 2,2'-thiobis-(4-methyl-6-t-butylphenol), and 4,4'-thiobis-(6-t-butyl-o-cresol), with styrene phenol and 2,4-bis[(octylthio)methyl]-6-methylphenol being preferred.

[0103] These antioxidants can be used individually or in combination of two or more. The content of the antioxidant in the hydrogenated nitrile rubber is not particularly limited, but is usually in the range of 0.001 to 2% by mass, preferably 0.01 to 1% by mass, more preferably 0.05 to 0.5% by mass, even more preferably 0.1 to 0.5% by mass, and most preferably 0.1 to 0.3% by mass. If the content of the antioxidant in the hydrogenated nitrile rubber is excessively low, the stability of the dispersion with the conductive material and the peel strength of the electrode will be poor, and if it is excessively high, it will affect the cycle characteristics of the electrochemical element.

[0104] (Characteristics) One embodiment of the hydrogenated nitrile rubber of the present invention includes the above repeating units and has the characteristics of having a specific iodine value, a specific bulk density, a specific weight-average molecular weight (Mw), and a specific ash content reduced.

[0105] Another aspect of the hydrogenated nitrile rubber of the present invention includes the above repeating units and has properties of a specific iodine value, a specific bulk density, a specific weight-average molecular weight (Mw), a specific ratio of Z-average molecular weight (Mz) to weight-average molecular weight (Mw) (Mz / Mw), and a specific reduced ash content.

[0106] Another embodiment of the hydrogenated nitrile rubber of the present invention comprises the above-mentioned repeating units and an anti-aging agent, and has properties of reduced specific iodine value, specific bulk density, and specific ash content.

[0107] The iodine value of the hydrogenated nitrile rubber of the present invention is 100 mg / 100 mg or less, preferably 80 mg / 100 mg or less, more preferably 60 mg / 100 mg or less, and preferably in the order of 50 mg / 100 mg or less, 40 mg / 100 mg or less, 30 mg / 100 mg or less, 20 mg / 100 mg or less, and 10 mg / 100 mg or less, with the lower limit usually being 0.1 mg / 100 mg or more, preferably 0.5 mg / 100 mg or more, more preferably 1 mg / 100 mg or more, even more preferably 1.5 mg / 100 mg or more, and most preferably 2 mg / 100 mg or more. When the iodine value of the hydrogenated nitrile rubber is within this range, the stability of the conductive material dispersion, the flexibility of the electrode, and the cycle characteristics of the electrochemical element can be greatly enhanced.

[0108] The bulk density of the hydrogenated nitrile rubber of the present invention is not particularly limited, but is typically 0.7 g / cm³. ３ Preferably, the concentration is 0.72 g / cm³. ３ , more preferably 0.73 g / cm³ ３ The above, or 0.75 g / cm³ ３ Above, 0.77g / cm ３ Above, 0.8g / cm ３ Above, 0.83g / cm ３ Above, 0.85g / cm ３ Above, 0.87g / cm ３ Above, 0.9g / cm ３ Above, 0.91g / cm ３ Above, 0.92g / cm ３ Above, 0.93g / cm ３ Above, 0.94g / cm ３ Above, 0.95g / cm ３ The above order of preference is preferred. When the bulk density of the hydrogenated nitrile rubber is within this range, the stability of the conductive material dispersion can be significantly improved, making it preferable.

[0109] The weight-average molecular weight (Mw) of the hydrogenated nitrile rubber of the present invention (weight-average molecular weight measured using tetrahydrofuran (THF)) is not particularly limited, but is usually 10,000 or more, preferably 30,000 or more, more preferably 50,000 or more, or preferably in the order of 70,000 or more, 100,000 or more, 130,000 or more, 150,000 or more, and 200,000 or more, and usually 5,000,000 or less, preferably 3,000,000 or less, more preferably 1,500,000 or less, or preferably in the order of 1,000,000 or less, 750,000 or less, and 500,000 or less. When the Mw of the hydrogenated nitrile rubber is in this range, the dispersibility of conductive materials is significantly improved, the peel strength of the manufactured electrodes and the resistance characteristics of the electrochemical elements are enhanced, and these characteristics can be highly balanced.

[0110] In the hydrogenated nitrile rubber of the present invention, when the weight-average molecular weight (NMP-Mw) measured with N-methylpyrrolidone (NMP) as the solvent and the weight-average molecular weight (THF-Mw) measured with tetrahydrofuran (THF) as the solvent satisfy the relationship NMP-Mw ≥ THF-Mw, the dispersibility and stability of the conductive material dispersion using NMP as the solvent can be greatly improved.

[0111] The ratio (NMP-Mw / THF-Mw) of the weight-average molecular weight (NMP-Mw) of the hydrogenated nitrile rubber of the present invention, measured using N-methylpyrrolidone (NMP) as a solvent, to the weight-average molecular weight (THF-Mw) measured using tetrahydrofuran (THF) as a solvent, is not particularly limited, but is usually 1 or more, preferably 1.01 or more, more preferably 1.02 or more, even more preferably 1.05 or more, and most preferably 1.1 or more. The upper limit is not particularly limited, but is usually 3 or less, preferably 2.5 or less, more preferably 2.2 or less, even more preferably 2 or less, and most preferably 1.5 or less. When the NMP-Mw / THF-Mw of the hydrogenated nitrile rubber is within this range, the dispersibility and stability of the conductive material dispersion using NMP as a solvent can be greatly improved.

[0112] The ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) of the hydrogenated nitrile rubber of the present invention (Mw / Mn) (measured using tetrahydrofuran (THF)) is not particularly limited, but is usually 1.2 or higher, preferably 1.5 or higher, more preferably 2 or higher, or preferably 2.1 or higher, 2.2 or higher, 2.3 or higher, 2.4 or higher, 2.5 or higher, and 2.6 or higher in that order, and usually 7 or lower, preferably 6 or lower, more preferably 5 or lower, or preferably 4.7 or lower, 4.5 or lower, 4.3 or lower, 4 or lower, 3.9 or lower, 3.8 or lower, 3.7 or lower, 3.6 or lower, and 3.5 or lower in that order. When the Mw / Mn of the hydrogenated nitrile rubber is within this range, the output characteristics and cycle characteristics of the electrochemical element can be greatly improved.

[0113] The ratio of the Z-average molecular weight (Mz) to the weight-average molecular weight (Mw) of the hydrogenated nitrile rubber of the present invention (Mz / Mw) (measured using tetrahydrofuran (THF)) is not particularly limited, but is usually 1.5 or higher, preferably 1.6 or higher, more preferably 1.7 or higher, or preferably in the order of 1.8 or higher, 1.9 or higher, 2 or higher, 2.1 or higher, 2.2 or higher, and 2.3 or higher, and is usually 7 or lower, preferably 6 or lower, more preferably 5 or lower, or preferably in the order of 4.5 or lower, 4 or lower, 3.5 or lower, and 3 or lower. When the Mz / Mw of the hydrogenated nitrile rubber is within this range, the dispersibility of the conductive material dispersion, the peel strength of the electrode, and the resistance characteristics of the electrochemical element can be improved.

[0114] In the particle size distribution of the hydrogenated nitrile rubber of the present invention, the ratio of particle size D90 when 90% of the total volume is present to particle size D10 when 10% of the total volume is present (D90 / D10) is not particularly limited, but is usually 170 or less, preferably 160 or less, more preferably 150 or less, or preferably in the order of 140 or less, 130 or less, 120 or less, 110 or less, 100 or less, 90 or less, 80 or less, 70 or less, 60 or less, and 50 or less. When the D90 / D10 of the hydrogenated nitrile rubber is within this range, the long-term storage properties of the positive electrode binder can be greatly improved. The lower limit of the D90 / D10 of the hydrogenated nitrile rubber is not particularly limited, but is usually 5 or more, preferably 10 or more, more preferably 15 or more, which can improve the warpage characteristics of the manufactured electrode and the capacitance characteristics of the electrochemical element.

[0115] In the particle size distribution of the hydrogenated nitrile rubber of the present invention, the ratio (D50 / D10) of the particle size D50 when 50% of the total volume is present (median diameter) to the particle size D10 when 10% of the total volume is present is not particularly limited, but is usually 70 or less, preferably 65 or less, more preferably 60 or less, or preferably in the order of 55 or less, 50 or less, 45 or less, 40 or less, 35 or less, 30 or less, and 25 or less. When the D50 / D10 of the hydrogenated nitrile rubber is within this range, the long-term storage properties of the positive electrode binder can be greatly improved. The lower limit of the D50 / D10 of the hydrogenated nitrile rubber is not particularly limited, but is usually 1 or more, preferably 3 or more, more preferably 5 or more, which can improve the warpage characteristics of the manufactured electrode and the capacitance characteristics of the electrochemical element.

[0116] The ash content of the hydrogenated nitrile rubber of the present invention is 0.7% by mass or less, preferably 0.65% by mass or less, more preferably 0.6% by mass or less, or preferably in the order of 0.55% by mass or less, 0.5% by mass or less, 0.45% by mass or less, 0.4% by mass or less, 0.35% by mass or less, 0.3% by mass or less, 0.25% by mass or less, and 0.2% by mass or less. When the ash content in the hydrogenated nitrile rubber is within this range, it is preferable because it suppresses the increase in resistance when the electrochemical element is stored at high temperatures, and also suppresses the deterioration of capacitance characteristics and cycle characteristics due to the destruction of the negative electrode active material, etc. There is no particular limit to the ash content in hydrogenated nitrile rubber, but it is usually 0.01% by mass or more, preferably 0.02% by mass or more, more preferably 0.03% by mass or more, or preferably in the order of 0.04% by mass or more, 0.05% by mass or more, 0.06% by mass or more, 0.07% by mass or more, 0.08% by mass or more, 0.09% by mass or more, and 0.1% by mass or more, and the hydrogenated nitrile rubber that is hydrogenated at this time can have its electrode peel strength increased.

[0117] The ratio of the total amount (Ca + S) of calcium content (Ca) and sulfur content (S) in the ash of the hydrogenated nitrile rubber of the present invention is not particularly limited, but is usually 30% by mass or more, preferably 35% by mass or more, more preferably 40% by mass or more, or preferably in the order of 43% by mass or more, 45% by mass or more, 47% by mass or more, 50% by mass or more, 55% by mass or more, 60% by mass or more, 65% by mass or more, 70% by mass or more, 75% by mass or more, 80% by mass or more, 85% by mass or more, and 90% by mass or more. When the ratio of the total amount (Ca + S) of calcium content (Ca) and sulfur content (S) in the ash of the hydrogenated nitrile rubber is within this range, the electrode peel strength is increased, the increase in resistance during high-temperature storage of the electrochemical element is suppressed, and the decrease in capacity characteristics and cycle characteristics due to the destruction of the negative electrode active material is suppressed.

[0118] The total amount of sodium (Na) and potassium (K) content (Na+K) in the ash of the hydrogenated nitrile rubber of the present invention is not particularly limited, but is usually 50% by mass or less, preferably 40% by mass or less, more preferably 30% by mass or less, or preferably in the order of 25% by mass or less, 20% by mass or less, 15% by mass or less, 10% by mass or less, 5% by mass or less, 3% by mass, 2% by mass or less, and 1% by mass or less. When the total amount of sodium (Na) and potassium (K) content (Na+K) in the ash of the hydrogenated nitrile rubber is within this range, the decrease in capacitance characteristics due to the breakdown of the negative electrode active material of the electrochemical element can be suppressed, and the increase in resistance during high-temperature storage can be suppressed.

[0119] The mass ratio ((Na+K) / (Ca+S)) of the total amount of sodium (Na) and potassium (K) content (Na+K) in the ash of the hydrogenated nitrile rubber of the present invention to the total amount of calcium (Ca) and sulfur (S) content (Ca+S) is not particularly limited, but is usually 0.7 or less, preferably 0.6 or less, more preferably 0.5 or less, or preferably in the order of 0.4 or less, 0.3 or less, 0.25 or less, 0.2 or less, 0.15 or less, 0.1 or less, 0.09 or less, 0.08 or less, 0.07 or less, 0.06 or less, 0.05 or less, 0.04 or less, and 0.03 or less, is most preferable. When the ratio is within this range, the electrode peel strength is increased, the increase in resistance during high-temperature storage of the electrochemical element is suppressed, and the deterioration of capacitance characteristics and cycle characteristics due to the destruction of the negative electrode active material is suppressed.

[0120] The mass ratio (Ca / S) of calcium content (Ca) to sulfur content (S) in the ash of the hydrogenated nitrile rubber of the present invention is not particularly limited, but is usually 10 or less, preferably 7 or less, more preferably 5 or less, or preferably in the order of 4.5 or less, 4 or less, 3.5 or less, 3.4 or less, 3.3 or less, 3.2 or less, 3.1 or less, 3 or less, 2.9 or less, 2.8 or less, 2.7 or less, 2.6 or less, 2.5 or less, 2 or less, 1.5 or less, 1.3 or less, 1.2 or less, and 1.15 or less, and is usually 0.1 or more, preferably 0.3 or more, more preferably 0.5 or more, or preferably in the order of 0.6 or more, 0.7 or more, 0.8 or more, and 0.9 or more. When the mass ratio (Ca / S) of calcium content (Ca) to sulfur content (S) in the ash of hydrogenated nitrile rubber is within this range, the electrode peel strength is increased, the increase in resistance of the resulting electrochemical element during high-temperature storage is suppressed, and the decrease in capacitance characteristics due to the breakdown of the negative electrode active material is suppressed.

[0121] The mass ratio (Ca / Cl) of calcium content (Ca) to chlorine content (Cl) in the ash of the hydrogenated nitrile rubber of the present invention is not particularly limited, but is usually 0.5 or more, preferably 0.6 or more, more preferably 0.7 or more, or preferably in the order of 0.8 or more, 0.9 or more, 1 or more, 1.2 or more, 1.4 or more, 1.5 or more, 1.6 or more, 1.8 or more, 2 or more, 2.5 or more, 3 or more, 3.5 or more, 4 or more, 5 or more, 10 or more, 20 or more, and 50 or more, is usually 100 or less, preferably 90 or less, more preferably 80 or less, even more preferably 75 or less, and most preferably 70 or less. When the mass ratio (Ca / Cl) of calcium content (Ca) to chlorine content (Cl) in the ash of the hydrogenated nitrile rubber is within this range, the electrode peel strength can be increased and the decrease in the cycle characteristics of the resulting electrochemical element can be suppressed.

[0122] The mass ratio (S / Cl) of sulfur content (S) to chlorine content (Cl) in the ash of the hydrogenated nitrile rubber of the present invention is not particularly limited, but is usually 0.3 or more, preferably 0.5 or more, more preferably 0.7 or more, or preferably in the order of 1 or more, 1.2 or more, 1.5 or more, 2 or more, 2.5 or more, 3 or more, 3.5 or more, 4 or more, 4.5 or more, 5 or more, 10 or more, 30 or more, and 50 or more, is usually 100 or less, preferably 90 or less, more preferably 80 or less, even more preferably 75 or less, and most preferably 70 or less. When the mass ratio (S / Cl) of sulfur content (S) to chlorine content (Cl) in the ash of the hydrogenated nitrile rubber is within this range, the electrode peel strength is increased, the increase in resistance during high-temperature storage of the electrochemical element is suppressed, and the decrease in capacitance characteristics and cycle characteristics due to the destruction of the negative electrode active material is suppressed.

[0123] The calcium content (Ca) in the ash of the hydrogenated nitrile rubber of the present invention is not particularly limited, but is usually 10% by mass or more, preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 35% by mass or more, most preferably 40% by mass or more, and usually within the range of 90% by mass or less, preferably 80% by mass or less, more preferably 70% by mass or less, even more preferably 60% by mass or less, and most preferably 50% by mass or less. When the calcium content (Ca) in the ash of the hydrogenated nitrile rubber is within this range, the electrode peel strength is increased, the increase in resistance during high-temperature storage of the electrochemical element is suppressed, and the deterioration of capacity characteristics and cycle characteristics due to the destruction of the negative electrode active material is suppressed.

[0124] The sulfur content (S) in the ash of the hydrogenated nitrile rubber of the present invention is not particularly limited, but is usually 5% by mass or more, preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, most preferably 25% by mass or more, and usually 80% by mass or less, preferably 70% by mass or less, more preferably 60% by mass or less, even more preferably 50% by mass or less, and most preferably 45% by mass or less. When the sulfur content (S) in the ash of the hydrogenated nitrile rubber is within this range, the electrode peel strength is increased, the increase in resistance during high-temperature storage of the electrochemical element is suppressed, and the deterioration of capacity characteristics and cycle characteristics due to the destruction of the negative electrode active material is suppressed.

[0125] The chlorine content (Cl) in the ash of the hydrogenated nitrile rubber of the present invention is not particularly limited, but is usually 50% by mass or less, preferably 40% by mass or less, more preferably 30% by mass or less, or preferably in the order of 25% by mass or less, 20% by mass or less, 15% by mass or less, and 10% by mass or less. When the chlorine content (Cl) in the ash of the hydrogenated nitrile rubber is within this range, effects such as the cycle characteristics of the electrochemical element and the suppression of resistance increase during high-temperature storage are improved.

[0126] The total amount of sodium (Na) and potassium (K) content (Na+K) in the ash of the hydrogenated nitrile rubber of the present invention is not particularly limited, but is usually 1500 ppm or less, preferably 1000 ppm or less, more preferably 800 ppm or less, or preferably in the order of 700 ppm or less, 600 ppm or less, 500 ppm or less, 450 ppm or less, 400 ppm or less, 350 ppm or less, 300 ppm or less, 250 ppm or less, 200 ppm or less, 150 ppm or less, and 100 ppm or less. When the total amount of sodium (Na) and potassium (K) content (Na+K) in the ash of the hydrogenated nitrile rubber is within this range, the decrease in battery capacity and cycle characteristics due to the destruction of the negative electrode active material can be suppressed.

[0127] The sodium content (Na) in the ash of the hydrogenated nitrile rubber of the present invention is not particularly limited, but is usually 700 ppm or less, preferably 500 ppm or less, more preferably 400 ppm or less, or preferably in the order of 350 ppm or less, 300 ppm or less, 250 ppm or less, 200 ppm or less, 150 ppm or less, 100 ppm or less, 70 ppm or less, and 50 ppm or less. When the sodium content (Na) in the ash of the hydrogenated nitrile rubber is within this range, the decrease in battery capacity and cycle characteristics due to the destruction of the negative electrode active material can be suppressed.

[0128] The potassium content (K) in the ash of the hydrogenated nitrile rubber of the present invention is not particularly limited, but is usually 700 ppm or less, preferably 500 ppm or less, more preferably 400 ppm or less, or preferably in the order of 350 ppm or less, 300 ppm or less, 250 ppm or less, 200 ppm or less, 150 ppm or less, 100 ppm or less, 70 ppm or less, and 50 ppm or less. When the potassium content (K) in the ash of the hydrogenated nitrile rubber is within this range, the decrease in battery capacity and cycle characteristics due to the destruction of the negative electrode active material can be suppressed.

[0129] The total amount (Ru + Rh) of ruthenium content (Ru) and rhodium content (Rh) in the ash of the hydrogenated nitrile rubber of the present invention is not particularly limited, but is usually 5% by mass or less, preferably 4% by mass or less, more preferably 3% by mass or less, or preferably in the order of 2% by mass or less, 1.5% by mass or less, 1% by mass or less, 0.7% by mass or less, 0.5% by mass or less, 0.3% by mass or less, and 0.1% by mass or less.

[0130] The palladium content (Pd) in the ash of the hydrogenated nitrile rubber of the present invention is not particularly limited, but is usually 5% by mass or less, preferably 4% by mass or less, more preferably 3% by mass or less, or preferably in the order of 2% by mass or less, 1.5% by mass or less, 1% by mass or less, 0.7% by mass or less, 0.5% by mass or less, 0.3% by mass or less, and 0.1% by mass or less.

[0131] The metal content (M) ratio used in the hydrogenation catalyst in the ash of the hydrogenated nitrile rubber of the present invention is not particularly limited, but for example, the total amount (Ru + Rh + Pd) of ruthenium content (Ru), rhodium content (Rh), and palladium content (Pd) in the ash is usually 5% by mass or less, preferably 4% by mass or less, more preferably 3% by mass or less, or preferably in the order of 2% by mass or less, 1.5% by mass or less, 1% by mass or less, 0.7% by mass or less, 0.5% by mass or less, 0.3% by mass or less, and 0.1% by mass or less.

[0132] The phosphorus content (P) in the ash of the hydrogenated nitrile rubber of the present invention is not particularly limited, but is usually 30% by mass or less, preferably 25% by mass or less, more preferably 20% by mass or less, even more preferably 15% by mass or less, particularly preferably 10% by mass or less, and most preferably 5% by mass or less. When the phosphorus content (P) in the ash of the hydrogenated nitrile rubber is within this range, the cycle characteristics of the resulting electrochemical element are improved and it is preferable.

[0133] The polymer pH of the hydrogenated nitrile rubber of the present invention is not particularly limited, but is usually 2 or higher, preferably 2.5 or higher, more preferably 3 or higher, or preferably in the order of 3.5 or higher, 4 or higher, 4.5 or higher, 4.6 or higher, 4.7 or higher, 4.8 or higher, 4.9 or higher, and 5 or higher, and is usually 8 or lower, preferably 7.5 or lower, more preferably 7 or lower, even more preferably 6.5 or lower, and most preferably 6 or lower. When the pH of the hydrogenated nitrile rubber is within this range, the viscosity stability of the cathode slurry can be increased, and the capacitance and resistance characteristics of the electrochemical element can be improved.

[0134] The water content of the hydrogenated nitrile rubber of the present invention is not particularly limited, but is usually less than 1% by mass, preferably 0.8% by mass or less, more preferably 0.7% by mass or less, even more preferably 0.6% by mass or less, and most preferably 0.5% by mass or less.

[0135] The hydrogenated nitrile rubber of the present invention is not limited by the manufacturing process, but it is preferably a polymer obtained by emulsion polymerization of acrylonitrile and 1,3-butadiene using an alkali metal salt as a polymerization auxiliary material, and then hydrogenated.

[0136] Polymerization auxiliary materials refer to substances other than monomers and polymerization initiators used to ensure stable emulsion polymerization. Examples include emulsifiers, pH adjusters, chain transfer agents (molecular weight adjusters), chelating agents, and reducing agents. There are no particular limitations on alkali metal salts used as polymerization auxiliary materials, but typical examples include potassium fatty acid and sodium dodecylbenzenesulfonate as emulsifiers. Other examples include sodium salts of mono- and di-sulfonated naphthalene sulfonic acid mixtures having isobutylene oligomer substituents, sodium salts of methylenebis(naphthalene sulfonate), and sodium phosphate as stabilizers. When alkali metal salts such as sodium or potassium salts are used as polymerization auxiliary materials, a uniform micelle structure and a uniform polymer can be produced, and the dispersibility and stability of the conductive material dispersion are excellent. However, differences in polymer structure occur that cannot be explained by measurable characteristic values ​​alone, and it is not possible to measure what type or shape of residue remains in the polymer after the polymerization auxiliary materials react. Furthermore, the polymerization auxiliary materials used remain in the crumb formed during the solidification reaction after polymerization and are difficult to remove. However, those using alkali metal salts are preferable because, due to the special crumb shape described later, they are easily removed by washing and dewatering. On the other hand, while the reduction of alkali metal salts from the polymer can be measured by the sodium (Na) and potassium (K) content in the ash, the effect on the properties of hydrogenated hydrogenated nitrile rubber varies greatly depending not only on the amount of Na and K in the ash but also on the type of counteranion, and these cannot be identified.

[0137] The hydrogenated nitrile rubber of the present invention is preferably obtained by hydrogenating a polymer obtained by emulsion polymerization of acrylonitrile and 1,3-butadiene using sulfates and / or sulfonates as polymerization auxiliary materials.

[0138] Examples of sulfates or sulfonic acids used as polymerization auxiliary materials include emulsifiers such as sodium dodecylbenzenesulfonate, reducing agents such as iron sulfate, sodium salts of mono- and di-sulfonated naphthalene sulfonic acid mixtures having isobutylene oligomer substituents, and sodium salts of methylenebis(naphthalene sulfonate). Polymerization auxiliary materials using sulfates and / or sulfonates are preferred because they are easily removed by cramb washing and dehydration, resulting in minimal impact on the resulting polymer. On the other hand, when examining the ash content in the polymer, it was found that when sulfates and / or sulfonates were used as polymerization auxiliary materials and calcium chloride was used as a coagulant, the ratio of calcium content (Ca) to sulfur content (S) in the ash was high. Furthermore, although the mass ratio of calcium to chlorine (Ca / Cl) of the calcium chloride used as a coagulant was 0.565, the mass ratio of calcium content (Ca) to chlorine content (Cl) in the ash (Ca / Cl) was much larger. It was inferred that during the coagulation reaction, some of the readily soluble calcium chloride was exchanged for acidic salts containing sparingly soluble sulfur and remained in the polymer. Although it is difficult to remove such sparingly soluble salts, by devising the coagulation reaction, washing, and dehydration processes described later, nitrile rubber with reduced sparingly soluble salts was obtained. Hydrogenated nitrile rubber obtained by hydrogenating this nitrile rubber suppressed gas generation and deterioration of cycle characteristics due to active material destruction during high-temperature storage of electrochemical elements. It was also found that the presence of sparingly soluble salts had the effect of increasing the peel strength of the electrodes. However, the effect of polymers with reduced levels of these poorly soluble salts cannot be explained solely by the calcium (Ca) and sulfur (S) content in the ash, and it is not possible to measure which specific salts are affecting the stability, dispersibility, and various properties of the conductive material dispersion and electrochemical elements.

[0139] The hydrogenated nitrile rubber of the present invention is preferably obtained by hydrogenating a polymer formed by emulsion polymerization of acrylonitrile and 1,3-butadiene and coagulation with calcium chloride.

[0140] When obtaining polymers by coagulating an emulsion polymerization solution, the size, shape, and properties of the resulting water-containing crumbs vary considerably depending on the type of coagulant used. This results in differences in the polymerization auxiliary materials that can be removed in subsequent washing and dehydration steps, as well as the various auxiliary material residues from the coagulation process. Furthermore, it is impossible to identify all trace amounts of these auxiliary materials and their reaction products. In particular, when hydrogenated nitrile rubber is used in electrochemical elements, these small amounts of residue affect various properties. Therefore, for electrochemical element applications, a solution using calcium chloride as a coagulant is preferable because, even if ash remains in the nitrile rubber or hydrogenated nitrile rubber, it exhibits excellent electrode peel strength characteristics and suppresses gas generation during high-temperature storage of the electrochemical element. Additionally, hydrogenated nitrile rubber obtained by hydrogenating nitrile rubber using alkali metal salts, sulfates, or sulfonates (preferably sulfates or sulfonates) as polymerization auxiliary materials and calcium chloride as a coagulant exhibits excellent electrode peel characteristics for electrochemical elements such as lithium-ion secondary batteries, and suppresses deterioration of cycle characteristics and gas generation during high-temperature storage compared to solutions using other coagulants.

[0141] The hydrogenated nitrile rubber of the present invention is preferably obtained by emulsion polymerization of acrylonitrile and 1,3-butadiene, adding an antioxidant, particularly a phenolic antioxidant, and then coagulating with calcium chloride to obtain a polymer, which is then hydrogenated.

[0142] The effectiveness of the above-mentioned specific antioxidant is far superior and preferable in nitrile rubber produced by adding it to an emulsion polymerization solution obtained by emulsion polymerization of acrylonitrile and 1,3-butadiene, rather than by mixing it with the nitrile rubber after production. Although this cannot be measured, it is thought that the phenolic antioxidant exhibits a high effect when the emulsion polymerization solution, in which the phenolic antioxidant is uniformly dispersed, is coagulated with calcium chloride, resulting in uniform and fine dispersion within the resulting nitrile rubber. In this invention, the antioxidant effect of the phenolic antioxidant is higher when added in the polymerization solution containing nitrile rubber after emulsion polymerization, rather than in the reaction solution containing hydrogenated nitrile rubber after hydrogenation. However, it is not possible to measure the state in which the antioxidant is thought to be uniformly dispersed in the nitrile rubber or hydrogenated nitrile rubber.

[0143] Preferably, the hydrogenated nitrile rubber of the present invention is obtained by melt-kneading hydrogenated nitrile rubber containing a phenolic antioxidant.

[0144] The effectiveness of the above-mentioned specific antioxidant can be significantly improved by melt-kneading the hydrogenated nitrile rubber containing the antioxidant using a screw-type twin-screw extruder or similar device. This is presumed to be because the phenolic antioxidant is more uniformly dispersed within the hydrogenated nitrile rubber upon melt-kneading, although this state of uniform dispersion cannot be measured.

[0145] <Method for Manufacturing Hydrogenated Nitrile Rubber> The hydrogenated nitrile rubber of the present invention is not particularly limited, but can be easily manufactured by the manufacturing method of the present invention, which comprises: an emulsion polymerization step of emulsion polymerization of monomer components containing acrylonitrile and 1,3-butadiene to obtain an emulsion polymerization liquid; an antioxidant addition step of adding an antioxidant to the obtained emulsion polymerization liquid; a coagulation step of adding the emulsion polymerization liquid with the antioxidant added to a coagulation liquid that is vigorously stirred to produce a water-containing crumb; a washing step of washing the produced water-containing crumb; a dehydration step of dehydrating the washed water-containing crumb to a water content of 35% by mass or less; a drying step of drying the polymer after dehydration; a hydrogenation step of dissolving the dried polymer in an organic solvent and carrying out a hydrogenation reaction; and a hydrogenated polymer dehydration and drying step of coagulating the reaction liquid after the hydrogenation reaction and dehydrating and drying the produced water-containing crumb using a screw-type twin-screw extruder to extrude the dried rubber.

[0146] (Emulsion polymerization process) The monomer components used are the same as those described for the monomer components of the repeating units, and the amounts used should be appropriately selected to achieve the monomer composition described above.

[0147] There are no particular limitations on the emulsifiers used in emulsion polymerization; they are selected according to conventional methods. Examples include salts of fatty acids such as myristic acid, palmitic acid, oleic acid, and linolenic acid; alkylbenzene sulfonates such as dodecylbenzenesulfonic acid; sulfate esters such as sodium lauryl sulfate; phosphate esters such as polyoxyalkylene alkyl ether phosphate esters; and alkyl sulfosuccinates. Among these, fatty acid salts, alkylbenzene sulfonates, and sulfate esters are preferred, with fatty acid salts and alkylbenzene sulfonates being particularly preferred.

[0148] Examples of salts such as fatty acid salts, alkylbenzene sulfonates, sulfate esters, and phosphate esters mentioned above include alkali metal salts and ammonium salts, with alkali metal salts being preferred, and sodium salts and potassium salts being particularly preferred. Specific examples of emulsifiers include potassium oleate, sodium oleate, potassium palmitate, sodium dodecylbenzenesulfonate, sodium lauryl sulfate, ammonium lauryl sulfate, sodium myristyl sulfate, sodium laureth sulfate, sodium polyoxyethylene alkyl sulfate, and sodium polyoxyethylene alkylaryl sulfate, with potassium oleate and sodium dodecylbenzenesulfonate being preferred.

[0149] These emulsifiers can be used individually or in combination of two or more, and the amount used is usually in the range of 0.01 to 10 parts by mass, preferably 0.1 to 5 parts by mass, and more preferably 1 to 3 parts by mass, per 100 parts by mass of monomer components.

[0150] The method for mixing the monomer component, emulsifier, and water can be done according to conventional methods, such as stirring the monomer, emulsifier, and water using a stirrer such as a homogenizer or a disk turbine. The amount of water used is usually in the range of 10 to 750 parts by mass, preferably 50 to 500 parts by mass, and more preferably 100 to 400 parts by mass, per 100 parts by mass of the monomer component.

[0151] In addition to the emulsifiers mentioned above, known polymerization auxiliary materials used in emulsion polymerization can be used after being appropriately optimized. Specifically, various polymerization regulators such as molecular weight regulators (chain transfer agents), pH adjusters, stabilizers, and reducing agents and chelating agents in redox catalysts can be used.

[0152] There are no particular limitations on the polymerization initiator used in emulsion polymerization, as long as it is one that is commonly used in emulsion polymerization; for example, a radical generator can be used.

[0153] Examples of radical generators include peroxides and azo compounds, with peroxides being preferred. Inorganic or organic peroxides are used. Organic peroxides are preferred to increase the number of 1,2-bonding units in the 1,3-butadiene polymerization units of nitrile rubber.

[0154] Examples of inorganic peroxides (inorganic polymerization initiators) include sodium persulfate, potassium persulfate, hydrogen peroxide, and ammonium persulfate. Among these, potassium persulfate, hydrogen peroxide, and ammonium persulfate are preferred, with potassium persulfate being particularly preferred.

[0155] As for organic peroxides (organic polymerization initiators), there are no particular limitations as long as they are known to be used in emulsion polymerization. For example, 2,2-di(4,4-di-(t-butylperoxy)cyclohexyl)propane, 1-di-(t-hexylperoxy)cyclohexane, 1,1-di-(t-butylperoxy)cyclohexane, 4,4-di-(t-butylperoxy)n-butyl valerate, 2,2-di-(t-butylperoxy)butane, t-butyl hydroperoxide, cumene hydroperoxide, diisopropyl Examples include pyrubenzene hydroperoxide, paramentane hydroperoxide, benzoyl peroxide, 1,1,3,3-tetraethylbutyl hydroperoxide, t-butylcumyl peroxide, di-t-butyl peroxide, di-t-hexyl peroxide, di(2-t-butylperoxyisopropyl)benzene, dicumyl peroxide, diisobutyryl peroxide, di(3,5,5-trimethylhexanoyl) peroxide, and dilauroyl peroxide.

[0156] These polymerization initiators can be used individually or in combination of two or more types, and the amount used is usually in the range of 0.0001 to 5 parts by mass, preferably 0.0005 to 1 part by mass, and more preferably 0.001 to 0.5 parts by mass, per 100 parts by mass of monomer component.

[0157] The amount of water used in the emulsion polymerization reaction may be limited to the amount used during the emulsion formation of the monomer components, but it is usually adjusted to be in the range of 10 to 1000 parts by mass, preferably 50 to 500 parts by mass, more preferably 80 to 400 parts by mass, and most preferably 100 to 300 parts by mass, per 100 parts by mass of the monomer components used for polymerization.

[0158] The emulsion polymerization reaction can be carried out according to a conventional method and may be batch, semi-batch, or continuous. The polymerization temperature and polymerization time are not particularly limited and can be appropriately selected depending on the type of polymerization initiator used. The polymerization temperature is usually in the range of 0 to 100°C, preferably 10 to 90°C, more preferably 20 to 80°C, even more preferably 25 to 70°C, and most preferably 30 to 60°C, and the polymerization time is usually 0.5 to 100 hours, preferably 1 to 10 hours. By setting the polymerization temperature higher, the 1,2-bonding units in the 1,3-butadiene polymerization units of the nitrile rubber, or the Mw / Mn and Mz / Mw of the nitrile rubber can be increased.

[0159] The polymerization conversion rate in the emulsion polymerization reaction is not particularly limited, but is usually 70% by mass or more, preferably 75% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more. Setting a higher polymerization conversion rate can increase the 1,2-bonding units in the 1,3-butadiene polymerization units of the nitrile rubber, or the Mw / Mn and Mz / Mw of the nitrile rubber. A polymerization inhibitor may be used to stop the polymerization.

[0160] (Addition of Anti-aging Agent) In the present invention, an anti-aging agent is added to the emulsion polymerization solution after the emulsion polymerization described above. Adding an anti-aging agent to the emulsion polymerization solution is preferable because it allows for uniform dispersion of the anti-aging agent in the resulting nitrile rubber or hydrogenated nitrile rubber. Furthermore, adding the anti-aging agent at this stage is preferable because it prevents deterioration reactions during the drying of the nitrile rubber.

[0161] The antioxidant used is the same as the example of the antioxidant contained in the hydrogenated nitrile rubber, and the method of adding the antioxidant to the emulsion polymerization solution is not particularly limited and can be done according to conventional methods. For example, it may be added as is, or it may be added after being emulsified with an emulsifier.

[0162] The amount of antioxidant used can be appropriately selected to match the amount of antioxidant in the hydrogenated nitrile rubber of the present invention, but is usually in the range of 0.001 to 15 parts by mass, preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, particularly preferably 0.3 to 3 parts by mass, and most preferably 0.5 to 2 parts by mass per 100 parts by mass of monomer component.

[0163] The emulsion polymerization solution after the addition of the antioxidant can be pH-adjusted with a buffer solution (sulfuric acid aqueous solution, potassium hydroxide aqueous solution) as needed. Adjusting the pH at this stage is preferable because it allows control of the pH of the hydrogenated nitrile rubber and removes impurities derived from the buffer solution.

[0164] The pH of the emulsion polymerization solution is not particularly limited, but is usually 2 or higher, preferably 2.5 or higher, more preferably 3 or higher, or preferably 3.5 or higher, 4 or higher, and 4.5 or higher in that order, and is usually 8 or lower, preferably 7.5 or lower, more preferably 7 or lower, even more preferably 6.5 or lower, and most preferably 6 or lower. By setting the pH of the emulsion polymerization solution within this range, the hydrogenated nitrile rubber produced can enhance the viscosity stability of the cathode slurry and improve the capacitance and resistance characteristics of the electrochemical element.

[0165] (Coagulation process) The coagulation reaction is a process in which a coagulation solution, preferably an aqueous calcium chloride solution, is brought into contact with an emulsion polymerization solution to produce a hydrated crumb. In particular, in the present invention, it is preferable to add the emulsion polymerization solution to which the above-mentioned antioxidant has been added to a coagulation solution that is being vigorously stirred.

[0166] The solid content concentration of the emulsion polymerization solution used is not particularly limited, but is usually adjusted to a range of 5 to 50% by mass, preferably 10 to 45% by mass, and more preferably 20 to 40% by mass.

[0167] While there are no particular limitations on the concentration of the coagulation solution used, it is generally preferable to use a concentration of 0.1 to 70% by mass, preferably 1 to 60% by mass, more preferably 5 to 50% by mass, and especially preferably 10 to 30% by mass, as this allows for the concentration of the water-containing crumb particle size within a specific range.

[0168] While there are no particular limitations on the temperature during the coagulation reaction, it is generally preferable to have a temperature of 0°C or higher, preferably 10 to 90°C, and more preferably 20 to 80°C, when a uniform hydrated crumb is produced.

[0169] In this method, it is preferable to add the emulsion polymerization solution to the vigorously agitated coagulation solution to carry out the coagulation reaction, which significantly improves the washing and dewatering efficiency of the resulting water-containing crumb. Furthermore, it is preferable to add the emulsion polymerization solution to the coagulation solution after it has been directly applied to the vigorously agitated impeller, rather than adding it to the coagulation solution itself, which also significantly improves the washing and dewatering efficiency of the resulting water-containing crumb. The water-containing crumb produced by this coagulation method is preferable because it significantly improves the washing and dewatering efficiency of the emulsifier and coagulant.

[0170] There are no particular limitations on the rotation speed of the stirring blade, but it is usually 100 rpm or more, preferably 200 rpm or more, more preferably 300 rpm or more, or preferably 350 rpm or more, 400 rpm or more, 450 rpm or more, 500 rpm or more, and 550 rpm or more in that order, and usually 1000 rpm or less, preferably 900 rpm or less, more preferably 800 rpm or less, even more preferably 750 rpm or less, and most preferably 700 rpm or less. It is preferable that the rotation speed of the stirring blade is above a certain level and the solidified liquid is vigorously stirred so that the diameter of the water-containing crumbs generated can be made smaller and concentrated in a specific region.

[0171] The peripheral velocity of the stirred solidified liquid is expressed as the linear velocity of the outer circumference of the stirring blade of the stirring device. It is preferable for the solidified liquid to be stirred vigorously to a certain extent, as this makes it possible to create smaller and more uniform water-containing cramb diameters. Typically, a peripheral velocity of 0.5 m / s or more is suitable, preferably 1 m / s or more, more preferably 1.5 m / s or more, particularly preferably 2 m / s or more, and most preferably 2.5 m / s or more. There is no particular upper limit to the peripheral velocity of the stirred solidified liquid, but it is generally easier to control the solidification reaction when the peripheral velocity is 50 m / s or less, preferably 30 m / s or less, more preferably 25 m / s or less, and particularly preferably 20 m / s or less.

[0172] As for the water-containing crumbs that are generated, for example, when sieving (classification) is performed using a JIS classifying sieve under the conditions (a) to (g) below, the proportion of water-containing crumbs with a diameter of 1.7 to 8 mm (passing through an 8 mm mesh opening but not a 1.7 mm mesh opening) to the generated water-containing crumbs is not particularly limited, but is usually 30% by mass or more, preferably 40% by mass or more, more preferably 50% by mass or more, or preferably in the order of 60% by mass or more, 70% by mass or more, 80% by mass or more, and 90% by mass or more. When the particle size of the generated water-containing crumbs is within this range, the washing efficiency and dewatering efficiency can be significantly increased, the ash content in the nitrile rubber can be reduced, and as a result the ash content in the hydrogenated nitrile rubber can be reduced.

[0173] The proportion of water-containing crumbs with a crumb diameter of 2.36 to 4.75 mm (passing through a 4.75 mm opening but not through a 2.36 mm opening) to the generated water-containing crumbs is not particularly limited, but is usually 20% by mass or more, preferably 30% by mass or more, more preferably 40% by mass or more, or preferably in the order of 50% by mass or more, 60% by mass or more, 70% by mass or more, and 80% by mass or more. When the particle size of the generated water-containing crumbs is within this range, the washing efficiency and dewatering efficiency can be significantly increased, the ash content in the nitrile rubber can be reduced, and as a result the ash content in the hydrogenated nitrile rubber can be reduced.

[0174] As for the resulting water-containing crumb, those that satisfy all of the following conditions (a) to (e) are preferable because they significantly improve the efficiency of removing emulsifiers and coagulants during washing and dewatering.

[0175] (a) The percentage of water-containing crumbs that do not pass through a JIS sieve with a mesh size of 9.5 mm is usually 10% by mass or less, preferably 5% by mass or less, and more preferably 3% by mass or less. (b) The percentage of relatively large water-containing crumbs that pass through a JIS sieve with a mesh size of 9.5 mm but do not pass through a JIS sieve with a mesh size of 8 mm is usually 25% by mass or less, preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, and most preferably 5% by mass or less. (c) The percentage of water-containing crumbs that pass through a JIS sieve with a mesh size of 8 mm but do not pass through a JIS sieve with a mesh size of 1.7 mm is usually 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and most preferably 90% by mass or more. (d) The percentage of water-containing crumbs that pass through a 1.7 mm mesh sieve but not through a 0.43 mm mesh JIS sieve is usually 25% by mass or less, preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, and most preferably 5% by mass or less. (e) The percentage of water-containing crumbs that pass through a 0.43 mm mesh JIS sieve is usually 10% by mass or less, preferably 5% by mass or less, and more preferably 3% by mass or less.

[0176] Furthermore, it is preferable that the resulting water-containing crumbs satisfy the following (f) and / or (g): (f) The percentage of water-containing crumbs that pass through a JIS sieve with a mesh size of 4.75 mm but not through a JIS sieve with a mesh size of 2.36 mm is usually 30% by mass or more, preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, and most preferably 70% by mass or more. (g) The percentage of water-containing crumbs that pass through a JIS sieve with a mesh size of 4.75 mm but not through a JIS sieve with a mesh size of 3.35 mm is usually 10% by mass or more, preferably 15% by mass or more, more preferably 20% by mass or more, even more preferably 25% by mass or more, and most preferably 30% by mass or more. In addition, there is no particular limit to the upper limit of water-containing crumbs in this range, but it is usually 90% by mass or less, preferably 85% by mass or less, more preferably 80% by mass or less, even more preferably 75% by mass or less, and most preferably 70% by mass or less.

[0177] The shape of the resulting water-containing crumbs is not particularly limited, but a perforated shape is preferred. In particular, adding the emulsion polymerization solution directly to the central rotating shaft and rotor blades in the vigorously rotating solidifying liquid increases the amount of perforated water-containing crumbs, which is preferable.

[0178] After the solidification process, the resulting water-containing crumb can be washed, dehydrated, and dried to obtain the polymer before hydrogenation.

[0179] (Washing Process) It is preferable to use hot water as the washing method. The temperature of the hot water is usually 30°C or higher, preferably 35 to 100°C, more preferably 40 to 80°C, even more preferably 40 to 60°C, and most preferably 40 to 50°C, as this can significantly increase the washing efficiency. Calcium sulfate and calcium sulfonate salts are poorly soluble and have low solubility, but their solubility tends to increase at certain temperatures. By setting the washing water temperature above the aforementioned lower limit, emulsifiers and coagulants are released from the water-containing crumb, further improving the washing efficiency.

[0180] The hydrated crumb, which has been solidified in a high-concentration coagulation solution (aqueous calcium chloride solution) during the solidification process, is effectively washed with a large amount of water. The amount of water used is typically 10 to 500 times, preferably 25 to 250 times, and more preferably 50 to 100 times, by mass per 100 parts by mass of polymer.

[0181] There are no particular limitations on the washing time, but it is usually in the range of 1 to 120 minutes, preferably 2 to 60 minutes, and more preferably 3 to 30 minutes.

[0182] (Dehydration process) Washed water-containing crumb is preferable because dehydration removes polymerization auxiliary materials such as emulsifiers trapped inside the water-containing crumb.

[0183] The water content of the dehydrated crumb is not particularly limited, but is usually 35% by mass or less, preferably 30% by mass or less, more preferably 25% by mass or less, or preferably in the order of 20% by mass or less, 15% by mass or less, 14% by mass or less, 13% by mass or less, 12% by mass or less, 10% by mass or less, 8% by mass or less, and 7% by mass or less.

[0184] There are no particular limitations on the method for dehydrating water-containing crumb, but a method that compresses and dehydrates the crumb using a squeezer or similar device to extract the internal moisture is preferable. On the other hand, dehydration using a centrifuge or the like is insufficient as it can only reduce the water content of the crumb to about 50-60% by mass.

[0185] The dehydration temperature is not particularly limited, but is usually 30°C or higher, preferably 40°C or higher, more preferably 50°C or higher, or preferably 60°C or higher, 70°C or higher, 80°C or higher, and 90°C or higher in that order. At this temperature range, the water-containing crumb becomes flexible, making it easier to remove moisture containing polymerization auxiliary materials, etc.

[0186] (Drying process) The drying method for the water-containing crumb after dewatering can be followed according to conventional methods, and can be dried using a dryer such as a hot air dryer, vacuum dryer, expander dryer, kneader dryer, or screw-type twin-screw extruder dryer.

[0187] The shape of the dried rubber (polymer) is not particularly limited and can be, for example, crumb-like, powder-like, rod-like, or sheet-like. The water content of the dried rubber is not particularly limited, but is usually less than 1% by mass, preferably 0.9% by mass or less, more preferably 0.8% by mass or less, even more preferably 0.6% by mass or less, and most preferably 0.5% by mass or less.

[0188] The nitrile rubber thus obtained can, if necessary, be subjected to a double decomposition reaction followed by a hydrogenation reaction to produce hydrogenated nitrile rubber.

[0189] (Double Decomposition Reaction) The double decomposition reaction of nitrile rubber can be carried out using, for example, the ruthenium catalyst described in Japanese Patent No. 4509792.

[0190] There are no particular limitations on the ruthenium-based catalyst used, and any known ruthenium-based catalyst can be used. In particular, it is preferable to use Grubbs catalysts such as bis(tricyclohexylphosphine)benzylideneruthenium dichloride or 1,3-bis(2,4,6-trimethylphenyl)-2-(imidazolidinylidene)(dichlorophenylmethylene)(tricyclohexylphosphine)ruthenium.

[0191] The double decomposition reaction is carried out by dissolving the substance in a solvent in the presence of a coolefin. Examples of coolefins include olefins having 2 to 16 carbon atoms such as ethylene, isobutane, styrene, and 1-hexane, as well as cis-2-butene-1,4-diol, 3-butene-1-amine, vinyltrimethoxysilane, methoxypolyalkylene glycol methacrylate, and 2-(methacryloyloxy)ethanesulfonic acid.

[0192] The amount of coolefin used is typically 0.1 to 20 parts by mass, preferably 0.5 to 10 parts by mass, and more preferably 1 to 5 parts by mass, per 100 parts by mass of polymer.

[0193] The reaction can be carried out in a solvent that does not inactivate the catalyst or interfere with the reaction. Preferred solvents are not limited to dichloromethane, but include, for example, dichloromethane, benzene, toluene, tetrahydrofuran, cyclohexane, and monochlorobenzene (MCB), with MCB being preferred. In some cases, the coolefin itself can act as a solvent, in which case no other solvent is required.

[0194] The polymer concentration in the double decomposition reaction is not particularly limited, but is usually in the range of 1 to 20% by mass, preferably 6 to 15% by mass.

[0195] The reaction solution in the double decomposition reaction is usually stirred vigorously, for example, in the range of 200 to 1000 rpm, preferably 300 to 900 rpm, and more preferably 500 to 800 rpm.

[0196] The temperature for the double decomposition reaction is typically in the range of 20 to 140°C, preferably 60 to 120°C. The reaction time depends on numerous factors, including the cement concentration, the amount of catalyst used, and the reaction temperature, but is usually completed within two hours. The progress of the double decomposition reaction can be monitored using standard analytical methods, such as GPC or solution viscosity.

[0197] (Hydrogenation reaction) The hydrogenation reaction can be carried out by dissolving nitrile rubber, or nitrile rubber that has undergone the double decomposition reaction as necessary, in a solvent (organic solvent) and adding a hydrogenation catalyst.

[0198] While there are no particular limitations on the solvent for the hydrogenation reaction, organic solvents that provide high hydrogenation efficiency for nitrile rubber are preferred. Suitable organic solvents include, for example, acetone, methyl ethyl ketone, ethyl acetate, tetrahydrofuran, 1,3-dioxane, benzene, toluene, methylene chloride, chloroform, monochlorobenzene (MCB), and dichlorobenzene. Among these, MCB is particularly preferred as it is a good solvent for both the nitrile group-containing nitrile rubber before hydrogenation and the hydrogenated nitrile rubber after hydrogenation.

[0199] There are no particular limitations on the hydrogenation catalyst, but it is usually carried out using a ruthenium-based catalyst. When the above double decomposition reaction is carried out using the Grubbs catalyst, the reaction vessel is subjected to hydrogen purging to produce a dihydrogen complex (PR), which is an olefin hydrogenation catalyst. ３ ) ２ RuCl ２ H ２ Since it is converted to , the process can be carried out continuously. In addition, dihydrogen complexes or other ruthenium-based catalysts can be used from the beginning. The hydrogenation reaction can be carried out according to a conventional method, for example, by the method described in Japanese Patent No. 6309634.

[0200] There are no particular limitations on hydrogenation catalysts other than ruthenium-based catalysts, but in particular, rhodium-based Wilkinson catalysts ((PPh ３ ) ３ Known homogeneous hydrogenation catalysts such as RhCl are preferred because they can be used with the same solvent as ruthenium-based catalysts and can be carried out without changing the reaction vessel. The hydrogenation reaction can be carried out according to a conventional method, for example, by the method described in Japanese Patent No. 6309634. In the case of the Wilkinson catalyst, examples of co-catalysts include phosphine, diphosphine, and triphenylphosphine, with triphenylphosphine being preferred. The amount of these co-catalysts used is usually in the range of 0.01 to 15 parts by mass, preferably 0.1 to 10 parts by mass, and more preferably 0.5 to 5 parts by mass, based on 100 parts by mass of the polymer to be hydrogenated.

[0201] The amount of hydrogenation catalyst used can be appropriately selected according to the purpose of use and the iodine value, but is usually in the range of 0.001 to 0.5 parts by mass, preferably 0.005 to 0.1 parts by mass and 0.01 to 0.05 parts by mass, based on 100 parts by mass of polymer before hydrogenation.

[0202] The polymer concentration in the hydrogenation reaction is not particularly limited as long as the polymer can be dissolved, but is usually in the range of 1 to 30% by mass, preferably 5 to 25% by mass, and more preferably 7 to 20% by mass.

[0203] The pressure for the hydrogenation reaction is not particularly limited, but is usually in the range of 0.1 to 30 MPa, preferably 1 to 20 MPa, and more preferably 5 to 15 MPa.

[0204] The hydrogenation reaction temperature is typically in the range of 30 to 200°C, preferably 50 to 170°C, and more preferably 100 to 150°C. The reaction time is typically 1 to 50 hours, preferably 2 to 25 hours.

[0205] The hydrogenation reaction can be stopped by reducing the pressure or cooling the reactor once the desired hydrogenation level is reached. Any remaining hydrogen is usually removed by nitrogen purging. The hydrogenation catalyst can also be removed before removing the solvent and isolating the hydrogenated nitrile rubber from the organic layer.

[0206] (Hydrogenation catalyst removal process) After the hydrogenation reaction, the hydrogenation catalyst can be removed as needed, and then the mixture can be dried to obtain hydrogenated nitrile rubber.

[0207] The hydrogenation catalyst can be removed by conventional methods, and for example, adsorbent treatment is preferred. The adsorbent is not particularly limited, but examples include activated carbon, ion exchange resin, and synthetic zeolite, with ion exchange resin being preferred.

[0208] The adsorbent treatment can be carried out by adding and mixing the adsorbent to the reaction solution containing hydrogenated nitrile rubber after hydrogenation. There are no particular limitations on the amount of adsorbent to add, but it is usually in the range of 0.001 to 1 part by mass, preferably 0.05 to 0.5 parts by mass, and more preferably 0.01 to 0.4 parts by mass, per 100 parts by mass of hydrogenated nitrile rubber. The mixing temperature is usually in the range of room temperature to 80°C, preferably room temperature to 60°C, and the mixing time is usually 1 minute to 1 hour, preferably 20 to 40 minutes.

[0209] After the adsorption treatment, the adsorbent can be removed by filtration or decantation, and the filtrate can be dried to obtain hydrogenated nitrile rubber.

[0210] <Recovery of Hydrogenated Nitrile Rubber by Screw-Type Twin-Screw Extruder> In the present invention, the water-containing crumb produced by coagulating the organic solvent reaction solution after the hydrogenation reaction, or the organic solvent filtrate after the adsorption treatment and filtration, is dehydrated and dried using a screw-type twin-screw extruder. (Coagulation Process) The coagulation process of the filtrate containing hydrogenated nitrile rubber from which impurities have been removed, obtained in the purification process (hydrogenation catalyst removal process), is not particularly limited and can be carried out according to conventional methods. Specific coagulation methods include contact with a coagulant and contact with a large amount of poor solvent, with contact with a large amount of poor solvent being preferred. There are no particular limitations as the poor solvent, but methanol, water, steam, etc., are suitably used. The coagulation reaction can be appropriately selected; for example, the coagulation reaction temperature is usually in the range of room temperature to 100°C, and the coagulation reaction time is appropriately selected in the range of several minutes to several hours.

[0211] The hydrated crumbs of hydrogenated nitrile rubber produced by the coagulation reaction can be washed as needed. While there are no particular limitations on the washing method, and any conventional method may be used, washing with a large amount of water is efficient. The amount of water used is typically 10 to 500 times, preferably 25 to 250 times, and more preferably 50 to 100 times, by mass per 100 parts by mass of polymer. While there are no particular limitations on the temperature of the water used for washing, warm water is preferable, typically 40°C or higher, preferably 40 to 100°C, more preferably 50 to 90°C, and most preferably 60 to 80°C, as this significantly improves washing efficiency. By raising the washing water temperature above the aforementioned lower limit, emulsifiers and coagulants are released from the hydrated crumbs, further improving washing efficiency.

[0212] After coagulation or washing, the water-containing crumb can be isolated by filtration.

[0213] (Dehydration and drying process using a screw-type twin-screw extruder) In the present invention, the water-containing crumb of the isolated hydrogenated nitrile rubber is dried using a screw-type twin-screw extruder. By melt-kneading and drying the hydrogenated nitrile rubber under reduced pressure in a screw-type twin-screw extruder, the internal air is removed, and a dry rubber (hydrogenated nitrile rubber) with a high bulk density is obtained. When used as a positive electrode material, it is suitable because it has excellent stability of the conductive material dispersion, prevents peel strength of the electrochemical element electrode, and prevents cracking of the active material layer after cycle testing.

[0214] Dewatering of the water-containing crumb in the dewatering barrel is performed in a dewatering barrel having dewatering slits. The opening of the dewatering slits can be appropriately selected according to the usage conditions, but it is generally preferable when it is in the range of 0.1 to 1 mm, preferably 0.2 to 0.6 mm, as this minimizes the loss of water-containing crumb and allows for efficient dewatering of the water-containing crumb.

[0215] The number of dewatering barrels in a screw-type twin-screw extruder dryer is not particularly limited, but it is generally preferable to have several barrels, preferably 2 to 10, and more preferably 3 to 6, for efficient dewatering of sticky hydrogenated nitrile rubber.

[0216] The set temperature of the dewatering barrel is appropriately selected depending on the type of hydrogenated nitrile rubber, ash content, water content, and operating conditions, but is usually in the range of 60 to 150°C, preferably 70 to 140°C, and more preferably 80 to 130°C. The set temperature of the dewatering barrel for dewatering in a drainage state is usually 60 to 120°C, preferably 70 to 110°C, and more preferably 80 to 100°C. The set temperature of the dewatering barrel for drying in a drainage steam state is usually in the range of 100 to 150°C, preferably 105 to 140°C, and more preferably 110 to 130°C.

[0217] There are no particular limitations on the water content after dehydration, which is obtained by squeezing out the water from the water-containing crumb, but it is usually 1 to 45% by mass, preferably 1 to 40% by mass, more preferably 3 to 35% by mass, and especially preferably 5 to 35% by mass.

[0218] Drying in the Drying Barrel The water-containing crumb dehydrated in the above-mentioned dewatering barrel is further dried in a drying barrel under reduced pressure. The degree of reduced pressure in the drying barrel can be selected as appropriate, but it is generally suitable when it is 1 to 50 kPa, preferably 2 to 30 kPa, and more preferably 3 to 20 kPa, as this allows for efficient drying of the water-containing crumb. Furthermore, by extruding the molten hydrogenated nitrile rubber through the drying barrel under reduced pressure, the internal air is also removed, making it possible to produce a sheet-like hydrogenated nitrile rubber with a high bulk density, which is preferable.

[0219] The drying barrel temperature can be selected as appropriate, but typically, a temperature of 100 to 250°C, preferably 110 to 200°C, and more preferably 120 to 180°C, allows for efficient drying without burning or deterioration of the hydrogenated nitrile rubber.

[0220] The number of drying barrels in a screw-type twin-screw extruder dryer is not particularly limited, but is usually several, preferably 2 to 10, and more preferably 3 to 8. When there are multiple drying barrels, the degree of reduced pressure may be similar for all drying barrels, or it may be varied. When there are multiple drying barrels, the set temperature may be similar for all drying barrels, or it may be varied, but it is preferable to make the temperature at the discharge section (closer to the die) higher than the temperature at the inlet section (closer to the dewatering barrel) to improve drying efficiency.

[0221] The water content of the dried rubber after drying is usually less than 1% by mass, preferably 0.8% by mass or less, and more preferably 0.6% by mass or less.

[0222] Extrusion of hydrogenated nitrile rubber (die section) The hydrogenated nitrile rubber, which has been dewatered and dried in the screw section of the dewatering barrel and drying barrel described above, is sent to a die section without a screw for straightening the flow. A breaker plate or wire mesh may or may not be provided between the screw section and the die section.

[0223] The extruded hydrogenated nitrile rubber can be obtained in various shapes, such as granular, columnar, round rod, or sheet, depending on the die nozzle shape. However, using a roughly rectangular die shape to extrude the rubber in sheet form is preferable because it reduces air entrapment, resulting in a dry rubber with high bulk density and excellent storage stability.

[0224] The resin pressure in the die section is not particularly limited, but it is generally preferable to set it in the range of 0.1 to 10 MPa, preferably 0.5 to 5 MPa, and more preferably 1 to 3 MPa, as this minimizes air entrapment and provides excellent productivity.

[0225] Screw-type twin-screw extruder dryer and operating conditions The screw length (L) of the screw-type twin-screw extruder dryer used can be appropriately selected according to the purpose of use, but is usually in the range of 3,000 to 15,000 mm, preferably 4,000 to 10,000 mm, and more preferably 4,500 to 8,000 mm.

[0226] The screw diameter (D) of the screw-type twin-screw extruder dryer used can be appropriately selected according to the intended use, but is usually in the range of 50 to 250 mm, preferably 100 to 200 mm, and more preferably 120 to 160 mm.

[0227] The ratio (L / D) of the screw length (L) to the screw diameter (D) of the screw-type twin-screw extruder dryer used is not particularly limited, but is usually in the range of 10 to 100, preferably 20 to 80, more preferably 30 to 60, and especially preferably 40 to 50, when it is possible to reduce the water content to less than 1% by mass without causing a decrease in molecular weight or burning of the dried rubber.

[0228] The rotational speed (N) of the screw-type twin-screw extruder dryer used can be appropriately selected according to various conditions, but is usually 10 to 1000 rpm, preferably 50 to 750 rpm, more preferably 100 to 500 rpm, and most preferably 120 to 300 rpm.

[0229] The extrusion rate (Q) of the screw-type twin-screw extruder dryer used is not particularly limited, but is usually in the range of 100 to 1500 kg / hr, preferably 300 to 1200 kg / hr, more preferably 400 to 1000 kg / hr, and most preferably 500 to 800 kg / hr.

[0230] The ratio of extrusion rate (Q) to rotational speed (N) (Q / N) of the screw-type twin-screw extruder dryer used is not particularly limited, but is usually in the range of 2 to 10, preferably 3 to 8, and more preferably 4 to 6.

[0231] The shape of the dried rubber extruded from a screw-type twin-screw extruder is not particularly limited, and examples include cramb, powder, rod, and sheet shapes, with the sheet shape being particularly preferred.

[0232] <Hydrogenated Nitrile Rubber Bale> The hydrogenated nitrile rubber bale of the present invention can be manufactured by forming a bale of the dried hydrogenated nitrile rubber described above.

[0233] The hydrogenated nitrile rubber bale of the present invention is made of the hydrogenated nitrile rubber, and by forming it into a bale, the effects of the hydrogenated nitrile rubber of the present invention can be maintained even during storage, making it suitable.

[0234] The shape of the hydrogenated nitrile rubber bale of the present invention is not particularly limited, but is usually rectangular. The size is not particularly limited, but the width is usually in the range of 100 to 800 mm, preferably 200 to 500 mm, more preferably 250 to 450 mm; the length is usually in the range of 300 to 1200 mm, preferably 400 to 1000 mm, more preferably 500 to 800 mm; and the height is usually in the range of 50 to 500 mm, preferably 100 to 300 mm, more preferably 150 to 250 mm.

[0235] The iodine value of the hydrogenated nitrile rubber bale of the present invention, the type and concentration of the antioxidant, the ash content, the ratio of the total amount of calcium content (Ca) and sulfur content (S) in the ash (Ca + S), the ratio of the total amount of sodium content (Na) and potassium content (K) in the ash (Na + K), the mass ratio of the total amount of sodium content (Na) and potassium content (K) in the ash (Na + K) to the total amount of calcium content (Ca) and sulfur content (S) (Ca + S) ((Na + K) / (Ca + S)), the mass ratio of calcium content (Ca) and sulfur content (S) in the ash (Ca / S), and the ash content The mass ratio of calcium content (Ca) to chlorine content (Cl) (Ca / Cl), the mass ratio of sulfur content (S) to chlorine content (Ca) in the ash (S / Cl), the proportion of metal content (M) in the hydrogenation catalyst in the ash, the proportion of the total amount of ruthenium content (Ru) and rhodium content (Rh) in the ash (Ru + Rh), the proportion of palladium content (Pd) in the ash, the total amount of sodium content (Na) and potassium content (K) in the ash (Na + K), the sodium content (Na) in the ash, the potassium content (K) in the ash, and the polymer pH are the same as described for the hydrogenated nitrile rubber.

[0236] The bulk density of the hydrogenated nitrile rubber bale of the present invention is not particularly limited, but is typically 0.6 g / cm³. ３ Preferably, the concentration is 0.63 g / cm³. ３ The above is a more preferable 0.65 g / cm³. ３ That is all, or 0.7 g / cm³. ３ Above, 0.73g / cm ３ Above, 0.75g / cm ３ Above, 0.77g / cm ３ Above, 0.8g / cm ３ Above, 0.83g / cm ３ Above, 0.85g / cm ３ Above, 0.87g / cm ３ Above, 0.9g / cm ３ Above, 0.91g / cm ３ Above, 0.92g / cm ３ Above, 0.93g / cm ３ Above, 0.94g / cm ３ Above, 0.95g / cm ３The above order of preference is preferred. When the bulk density of the hydrogenated nitrile rubber veil is within this range, the effect of the antioxidant, especially the phenolic antioxidant, is greatly enhanced, the stability of the conductive material dispersion is excellent, and the cycle characteristics of the electrochemical element and active material cracking after cycle testing can be prevented.

[0237] The water content of the hydrogenated nitrile rubber bale of the present invention is not particularly limited, but is generally less than 1% by mass, preferably 0.8% by mass or less, and more preferably 0.6% by mass or less, as it provides excellent storage stability and is therefore preferable.

[0238] The Mooney viscosity (ML1 + 4, 100°C) of the hydrogenated nitrile rubber bale of the present invention is not particularly limited, but is generally in the range of 10 to 150, preferably 15 to 100, and more preferably 20 to 80, when the dispersibility of conductive materials and peel strength at the electrode are well balanced and preferable.

[0239] The baling of dried hydrogenated nitrile rubber can be carried out according to conventional methods. For example, the dried rubber can be placed in a baler and compressed. The compression pressure is appropriately selected depending on the intended use, but is usually in the range of 0.1 to 15 MPa, preferably 0.5 to 10 MPa, and more preferably 1 to 5 MPa. The compression time is not particularly limited, but is usually in the range of 1 to 60 seconds, preferably 5 to 50 seconds, and more preferably 10 to 40 seconds. Alternatively, dried rubber can be made in sheet form and then laminated to form bales. Baling by laminating sheets is easy to manufacture, produces bales with fewer air bubbles (higher bulk density), and is preferable due to its excellent storage stability.

[0240] In the present invention, a suitable hydrogenated nitrile rubber bale with a high bulk density can be easily manufactured by laminating the sheet-like dried rubber (hydrogenated nitrile rubber) extruded from the screw-type twin-screw extruder.

[0241] <Positive electrode material and positive electrode binder> The positive electrode material of the present invention is characterized by using the hydrogenated nitrile rubber of the present invention.

[0242] The positive electrode binder of the present invention is obtained by dissolving the hydrogenated nitrile rubber in N-methylpyrrolidone (NMP), and is suitable as a material for manufacturing the positive electrode of an electrochemical element. Furthermore, the positive electrode binder of the present invention can be easily manufactured, for example, by adding an NMP solution to a hydrogenated nitrile rubber-containing monochlorobenzene solution obtained by hydrogenating nitrile rubber in monochlorobenzene, and then distilling off the monochlorobenzene solvent to perform solvent replacement.

[0243] The positive electrode binder of the present invention may combine other components as needed, in addition to hydrogenated nitrile rubber and NMP. These other components are not particularly limited, but examples include binders other than hydrogenated nitrile rubber (such as polyvinylidene fluoride or polyacrylate), reinforcing materials, leveling agents, viscosity modifiers, and electrolyte additives. These are not particularly limited as long as they do not affect the battery reaction, and known components can be used. Furthermore, the positive electrode binder of the present invention may contain solvents other than NMP, to the extent that they do not impair the properties of the present invention. These other components may be used individually or in combination of two or more types.

[0244] The solid content concentration of the positive electrode binder of the present invention is not particularly limited, but is usually in the range of 0.1 to 40% by mass, preferably 0.5 to 20% by mass, and more preferably 1 to 10% by mass.

[0245] The mixing method for hydrogenated nitrile rubber, NMP, and other components used as needed should follow conventional methods.

[0246] <Conductive Material Dispersion> The conductive material dispersion of the present invention is obtained by dissolving or dispersing the hydrogenated nitrile rubber and the conductive material in NMP. The conductive material dispersion of the present invention can be manufactured, for example, by mixing the positive electrode binder and the conductive material of the present invention.

[0247] (Conductive Material) The conductive material is a component that functions to ensure electrical contact between electrode active materials. Carbonaceous materials can be suitably used as the conductive material. Examples of such carbonaceous materials include carbon black (e.g., acetylene black, Ketjenblack®, furnace black, etc.), single-walled or multi-walled carbon nanotubes (multi-walled carbon nanotubes include cup-stacked type), carbon nanohorns, vapor-grown carbon fibers, milled carbon fibers obtained by crushing polymer fibers after firing, single-walled or multi-walled graphene, and carbon nonwoven fabric sheets obtained by firing nonwoven fabrics made of polymer fibers. These may be used individually or in combination of two or more in any ratio. Among these, carbon nanotubes (CNTs) are preferred from the viewpoint of forming good conductive paths.

[0248] When mixing the positive electrode binder and the conductive material of the present invention, the ratio of the conductive material to the positive electrode binder is not particularly limited. For example, the resulting conductive material dispersion may contain hydrogenated nitrile rubber in an amount of 1 to 100 parts by mass, preferably 5 to 50 parts by mass, and more preferably 10 to 30 parts by mass, per 100 parts by mass of conductive material. Furthermore, when mixing the positive electrode binder and the conductive material, NMP can be added as needed to adjust the viscosity.

[0249] The solid content concentration when the positive electrode binder and conductive material of the present invention are mixed is usually 0.01% by mass or more, preferably 1.0% by mass or more, and more preferably 3.0% by mass or more, and the upper limit is usually 10.0% by mass or less, preferably 9.0% by mass or less, and more preferably 8.0% by mass or less. If the solid content concentration is above the lower limit, the coating properties of the conductive material dispersion can be improved. Furthermore, if the solid content concentration is below the upper limit, the rate characteristics of the resulting electrochemical element can be improved.

[0250] The method for mixing the positive electrode binder and conductive material of the present invention is not particularly limited, and can be used, for example, with known mixing equipment.

[0251] <Positive Electrode Slurry> The positive electrode slurry of the present invention is obtained by dispersing or dissolving a positive electrode active material, a conductive material, and the hydrogenated nitrile rubber in N-methylpyrrolidone (NMP). Such a positive electrode slurry can be made by mixing the positive electrode binder and the conductive material with a solvent as needed, and then mixing in the positive electrode active material.

[0252] <Electrode for Electrochemical Element> The positive electrode of the present invention comprises the hydrogenated nitrile rubber and consists of a positive electrode composite layer comprising a binder containing the hydrogenated nitrile rubber, a conductive material, and a positive electrode active material, and a current collector. The positive electrode of the present invention can be manufactured by mixing the positive electrode binder and the conductive material with a solvent as needed, then mixing in the positive electrode active material, applying the slurry to the current collector, and then drying it.

[0253] (Positive electrode active material) The positive electrode active material is not particularly limited, but in the case of a lithium-ion secondary battery, a metal oxide containing lithium (Li) is an example. Preferably, the positive electrode active material contains lithium (Li) and at least one selected from the group consisting of cobalt (Co), nickel (Ni), manganese (Mn), and iron (Fe). An example of such a positive electrode active material is lithium-containing cobalt oxide (LiCoO). ２ ), lithium manganese (LiMn ２ O ４ ), lithium-containing nickel oxide (LiNiO ２ ), Co-Ni-Mn lithium-containing composite oxide, Ni-Mn-Al lithium-containing composite oxide, Ni-Co-Al lithium-containing composite oxide, olivine-type lithium manganese phosphate (LiMnPO ４ ), olivine-type lithium iron phosphate (LiFePO ４ ), Li １＋ｘ Mn ２－ｘ O ４ Lithium-rich spinel compounds represented by (0 < X ​​< 2), Li[Ni ０．１７ Li ０．２ Co ０．０７ Mn ０．５６ ]O ２ LiNi ０．５ Mn １．５ O ４, Li[Ni ０．５ Co ０．２ Mn ０．３ ]O ２ These are some examples. The particle size of the positive electrode active material is not particularly limited and can be the same as that of conventionally used electrode active materials. The positive electrode active material may be used alone, or two or more types may be used in any ratio.

[0254] The above-mentioned positive electrode active material can be mixed with the mixture of the positive electrode binder and conductive material to form a positive electrode slurry. The mixing method is not particularly limited and can be carried out using known mixing equipment. The amount of positive electrode active material is not particularly limited and can be within the range of conventionally used amounts.

[0255] (Current Collector) The current collector is made of a material that is electrically conductive and electrochemically durable. The current collector is not particularly limited and known current collectors can be used. For example, the current collector of the positive electrode of a lithium-ion secondary battery may be made of aluminum or an aluminum alloy. In this case, a combination of aluminum and an aluminum alloy may be used, or a combination of aluminum alloys of different types may be used. Aluminum and aluminum alloys are excellent current collector materials because they are heat resistant and electrochemically stable.

[0256] The positive electrode of the present invention can be manufactured by applying the above-described slurry for the positive electrode of the present invention to at least one surface of a current collector and drying it to form a positive electrode composite layer.

[0257] (Coating Process) The method for coating the positive electrode slurry onto the current collector is not particularly limited and any known method can be used. Specifically, the doctor blade method, dip method, reverse roll method, direct roll method, gravure method, extrusion method, brush coating method, etc., can be used as coating methods. In this case, the positive electrode slurry may be coated on only one side of the current collector or on both sides. The thickness of the slurry film on the current collector before drying after coating can be appropriately set according to the thickness of the positive electrode composite layer obtained after drying.

[0258] (Drying process) The method for drying the positive electrode composite layer slurry on the current collector is not particularly limited and known methods can be used, such as drying with hot air, hot air, low humidity air, vacuum drying, and drying by irradiation with infrared rays or electron beams. By drying the positive electrode composite layer slurry on the current collector in this way, a positive electrode composite layer is formed on the current collector, and a positive electrode comprising a current collector and a positive electrode composite layer can be obtained.

[0259] Furthermore, after the drying process, the electrode composite layer may be subjected to pressure treatment using a die press or roll press. Pressure treatment allows the positive electrode composite layer to adhere well to the current collector. In addition, if the positive electrode composite layer contains a curable polymer, the polymer may be cured after the formation of the positive electrode composite layer.

[0260] <Electrochemical Element> The electrochemical element of the present invention is characterized by containing the hydrogenated nitrile rubber of the present invention. The electrochemical element equipped with the positive electrode of the present invention described above has excellent capacitance characteristics, resistance characteristics, cycle characteristics and high-temperature storage characteristics, and is particularly preferably a lithium-ion secondary battery.

[0261] Herein, the configuration of a lithium-ion secondary battery as an example of the electrochemical element of the present invention will be described. This lithium-ion secondary battery comprises a positive electrode, a negative electrode, an electrolyte, and a separator, and the positive electrode is the electrode of the present invention.

[0262] (Negative electrode) The negative electrode is not particularly limited and any known electrode can be used.

[0263] (Electrolyte) Typically, an organic electrolyte is used, which is an organic electrolyte in which a supporting electrolyte is dissolved in an organic solvent. For example, lithium salts are used as supporting electrolytes. For example, LiPF ６ LiAsF ６ LiBF ４ LiSbF ６ LiAlCl ４ LiClO ４ CF ３ SO ３ Li, C ４ F ９ SO ３ Li, CF ３ COOLi, (CF３ CO) ２ NLi, (CF ３ SO ２ ) ２ NLi, (C ２ F ５ SO ２ )NLi, and the like. Among these, LiPF ６ , LiClO ４ , CF ３ SO ３ Li is preferable, and LiPF ６ is particularly preferable. One electrolyte may be used alone, or two or more electrolytes may be used in combination at any arbitrary ratio. Generally, the use of a supporting electrolyte with higher dissociation degree tends to result in higher lithium ion conductivity, so the lithium ion conductivity can be adjusted depending on the type of the supporting electrolyte.

[0264] The organic solvent used in the electrolytic solution is not particularly limited as long as it can dissolve the supporting electrolyte. For example, carbonates such as dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), butylene carbonate (BC), and methyl ethyl carbonate (EMC); esters such as γ-butyrolactone and methyl formate; ethers such as 1,2-dimethoxyethane and tetrahydrofuran; sulfur-containing compounds such as sulfolane and dimethyl sulfoxide; etc. are preferably used. Mixtures of these solvents may also be used. Among them, carbonates are preferably used because they have high dielectric constant and a wide stable potential range, and it is more preferable to use a mixture of ethylene carbonate and diethyl carbonate.

[0265] The concentration of the electrolyte in the electrolytic solution can be appropriately adjusted. For example, it is preferably 0.5 to 15% by mass, more preferably 2 to 13% by mass, and even more preferably 5 to 10% by mass. In addition, known additives such as vinylene carbonate, fluoroethylene carbonate, ethyl methyl sulfone, and the like may be added to the electrolytic solution.

[0266] (Separator) The separator is not particularly limited, and for example, those described in Japanese Patent Application Publication No. 2012-204303 can be used. Among these, a microporous membrane made of polyolefin resin (polyethylene, polypropylene, polybutene, polyvinyl chloride) is preferred because it allows for a thinner overall film thickness of the separator, thereby increasing the ratio of electrode active material in the lithium-ion secondary battery and thus increasing the capacity per unit volume.

[0267] (Method for manufacturing a lithium-ion secondary battery) A lithium-ion secondary battery according to the present invention can be manufactured, for example, by stacking a positive electrode and a negative electrode with a separator in between, winding or folding them as needed according to the battery shape, placing them in a battery container, injecting an electrolyte into the battery container, and sealing it. To prevent pressure rise inside the secondary battery, overcharge and discharge, etc., an overcurrent prevention element such as a fuse or PTC element, expanded metal, lead plates, etc. may be provided as needed. The shape of the secondary battery may be any of the following: coin type, button type, sheet type, cylindrical type, rectangular type, flat type, etc.

[0268] <Applications> The hydrogenated nitrile rubber of the present invention can exhibit its functionality and be effectively utilized in any electrochemical element other than the lithium-ion secondary battery described above. Examples of usable devices include non-aqueous electrolyte batteries such as lithium-ion batteries, sodium-ion batteries, potassium-ion batteries, magnesium-ion batteries, calcium-ion batteries, aluminum-ion batteries, lithium-sulfur batteries, and lithium-air batteries; inorganic solid electrolyte batteries such as sulfide-based solid electrolytes and oxide-based solid electrolytes; polymer solid electrolyte batteries such as polyethylene oxide-based batteries; and semi-solid batteries such as polymer gel electrolyte batteries in which electrolyte is impregnated into PVDF.

[0269] The hydrogenated nitrile rubber of the present invention can also be suitably used in organic electrolyte capacitors, aqueous electrolyte capacitors, and aqueous solution batteries. In fuel cells, it can be used in PEFCs, SOFCs, DMPCs, etc., and in particular, it can be used not only to impart conductivity to electrodes but also as a support for oxidation-reduction catalysts.

[0270] The hydrogenated nitrile rubber of the present invention can be used for applications other than electrochemical elements. Other suitable applications include, for example, seals, hoses, transmission belts, cable sheaths, roller covers, and vibration damping applications in the automotive sector; stators, well seals, and valve seals in the oil extraction sector; and various components in the aerospace, electrical, mechanical engineering, and shipbuilding industries.

[0271] <Configuration of the Nitrile Rubber Manufacturing System> The configuration of the nitrile rubber manufacturing system for manufacturing nitrile rubber according to the present invention will be described below. Figure 1 is a diagram showing an example of the nitrile rubber manufacturing system in an embodiment of the present invention.

[0272] Figure 1 schematically illustrates the apparatus configuration of a nitrile rubber manufacturing system according to an embodiment of the present invention, in accordance with the manufacturing process. The nitrile rubber manufacturing system shown in Figure 1 is generally configured to include an emulsion polymerization apparatus 10, a coagulation apparatus 30, a washing apparatus 50, and a squeezer 70.

[0273] (Emulsion polymerization apparatus 10) The emulsion polymerization apparatus 10 is configured to perform the processes related to the emulsion polymerization process. As shown in Figure 1, the emulsion polymerization apparatus 10 has a polymerization tank 11 and a stirring device 12 for copolymerizing monomer components such as acrylonitrile monomer and 1,3-butadiene monomer. The emulsion polymerization apparatus 10 may be batch type, semi-batch type, or chain type, and may be a tank reactor or a tubular reactor.

[0274] The polymerization vessel 11 is formed, for example, in a closed cylindrical shape so that it can store the emulsion polymerization liquid. The stirring device 12 is located inside the polymerization vessel 11 and includes a stirring blade 13 which is a member that rotates around a predetermined axis, a motor 14 that rotates the stirring blade 13, and a drive control unit (not shown) that controls the rotational number and rotational speed of the stirring blade 13.

[0275] A predetermined amount of acrylonitrile and 1,3-butadiene and water are placed in the polymerization vessel 11, polymerization auxiliary materials such as emulsifiers and molecular weight regulators are added, and nitrogen purging is performed to remove oxygen from the polymerization vessel 11. Then, a polymerization initiator is added while stirring to start the polymerization reaction.

[0276] The stirring device 12 is configured to rotate the stirring blades 13 at a predetermined rotational speed (stirring speed) inside the polymerization vessel 11, thereby enabling proper flow of the emulsion polymerization liquid. The stirring speed of the stirring blades 13, the shape and size of the stirring blades 13, the number of blades installed, etc., are determined appropriately considering the reaction conditions, etc.

[0277] The temperature of the emulsion polymerization solution inside the polymerization vessel 11 affects the reaction rate, molecular weight distribution, and molecular structure. For example, the proportion of 1,2-bond units in the polymerization units of 1,3-butadiene increases as the temperature of the emulsion polymerization solution increases and decreases as the temperature of the emulsion polymerization solution decreases, so this can be controlled by appropriately controlling the temperature of the emulsion polymerization solution.

[0278] When a predetermined polymerization conversion rate is reached, a polymerization stopper is added to the polymerization tank 11 to stop the polymerization reaction. The polymerization addition rate can be controlled to determine the molecular weight, molecular weight distribution, and the proportion of 1,2-bonding units in the 1,3-butadiene polymerization units of the nitrile rubber produced, so it can be appropriately selected according to the required properties. In addition, a process related to the addition of an anti-aging agent is carried out, and after the polymerization reaction is completed, the anti-aging agent is added to the polymerization tank 11. After that, the latex in the polymerization tank 11 is transferred to the solidification tank 31 of the solidification device 30.

[0279] (Solidification device 30) The solidification device 30 is configured to perform the processing related to the solidification process. As shown in Figure 1, the solidification device 30 has a solidification tank 31 and a stirring device 32 for solidifying the latex transferred from the emulsion polymerization device 10 and extracting crumb-shaped nitrile rubber (water-containing crumb).

[0280] The solidification tank 31 is formed, for example, in a closed cylindrical shape and is capable of storing a solidified liquid containing a solidifying agent (for example, calcium chloride). The stirring device 32 is located inside the solidification tank 31 and includes a stirring blade 33 which is a member that rotates around a predetermined axis, a motor 34 that rotates the stirring blade 33, and a drive control unit (not shown) that controls the rotational number and speed of the stirring blade 33.

[0281] In the coagulation apparatus 30, hydrated crumbs are generated by bringing the latex transferred from the emulsion polymerization apparatus 10 into contact with a coagulation solution containing a coagulant (e.g., calcium chloride). The method of contact between the latex and the coagulation solution is not particularly limited; for example, the latex may be added to the agitated coagulation solution, or the coagulation solution may be added to the agitated latex. In this embodiment, the coagulation apparatus 30 employs the method of adding the latex to the agitated coagulation solution. Adding the latex to the agitated coagulation solution concentrates the generated hydrated crumbs so that their shape and diameter are uniform, significantly improving the cleaning efficiency in the subsequent cleaning process.

[0282] The stirring device 32 is configured to rotate the stirring blades 33 at a predetermined rotational speed (stirring speed) within the solidification tank 31, thereby enabling proper flow of the solidified liquid. The stirring speed of the stirring blades 33, the shape and size of the stirring blades 33, the number of blades installed, etc., are determined appropriately considering the reaction conditions, etc., but it is preferable to configure the device to apply a strong shear force in order to generate smaller water-containing crumbs.

[0283] In the method of adding latex to a stirred solidifying solution, the solidifying solution and water (soft water) are filled into the solidifying tank 31 and stirred with the stirring blade 33, and the latex is added to the stirred solidifying solution. The latex that comes into contact with the solidifying solution solidifies and a water-containing crumb is formed.

[0284] The water-containing crumb generated in the solidification tank 31 is removed from the solidification tank 31 by overflowing it along with the solidification liquid and water-containing liquid. The water-containing crumb removed from the solidification tank 31 is transferred to the washing tank 51 of the washing device 50 via the dewatering machine 38.

[0285] As shown in Figure 1, a dewatering machine 38 is positioned between the solidification tank 31 and the washing tank 51. The dewatering machine 38 is configured to separate the water-containing crumb from the liquid (solidified liquid). A screen, wire mesh, electric sieve, etc., can be used for the dewatering machine 38.

[0286] (Washing device 50) The washing device 50 is configured to perform the processing related to the washing process. As shown in Figure 1, the washing device 50 has a washing tank 51 for receiving the water-containing crumb and washing water transferred from the solidification device 30, a stirring device 52, and a heating device 55.

[0287] The washing tank 51 is formed, for example, in a closed cylindrical shape and is capable of storing water-containing crumbs and washing water. The stirring device 52 is located inside the washing tank 51 and includes a stirring blade 53 which is a member that rotates around a predetermined axis, a motor 54 that rotates the stirring blade 53, and a drive control unit (not shown) that controls the rotational number and speed of the stirring blade 53. The heating device 55 includes a heating unit 56 that heats the inside of the washing tank 51, and a temperature control unit (not shown) that controls the temperature inside the washing tank 51.

[0288] The agitator 52 is configured to rotate the agitator blades 53 at a predetermined rotational speed (agitation speed) within the washing tank 51, thereby washing the water-containing crumbs by appropriately flowing the water-containing crumbs and washing water. The agitation speed of the agitator blades 53, the shape and size of the agitator blades 53, and the number of blades installed are determined appropriately considering the size of the water-containing crumbs and the washing efficiency.

[0289] The heating unit 56 of the heating device 55 sends steam to a jacket provided on the outer circumference of the washing tank 51, for example, and heats the washing liquid through heat exchange with the steam. The temperature of the washing water in the washing tank 51 is controlled to be, for example, 40°C or higher in order to improve the effect of releasing emulsifiers and coagulants from the water-containing crumb.

[0290] The water-containing crumb, washed in the washing tank 51, is removed from the washing tank 51 by overflowing with washing water. The water-containing crumb removed from the washing tank 51 is then transferred to the squeezer 70 via the dewatering machine 58.

[0291] (Squeezer 70) The squeezer 70 is configured to perform the dewatering process. In this embodiment, the squeezer 70 is used as the dewatering machine, but as a dewatering device for dewatering the water-containing crumb, for example, a screw-type twin-screw extruder dryer that performs dewatering and drying can be used.

[0292] As shown in Figure 1, the squeezer 70 has a two-stage configuration in which an upstream heating mechanism 71 and a downstream pressurizing mechanism 72 are connected by a connecting part 73.

[0293] The heating mechanism 71 includes a chamber 71a and a roller 71b for heating the water-containing cramb, a motor (not shown) that generates rotational power to rotate the roller 71b, and a heating device 71c that supplies steam into the chamber 71a. The roller 71b is housed in the chamber 71a so as to extend in the direction of conveying the water-containing cramb. The shape of the roller 71b is not particularly limited, but for example, it is formed in a screw shape.

[0294] At the upstream end of the chamber 71a, a crumb supply unit 70a is provided for introducing water-containing crumbs transferred from the washing device 50 into the chamber 71a. The downstream end of the chamber 71a is connected to a connecting unit 73. Steam at a predetermined temperature and pressure is supplied into the chamber 71a by a heating device 71c. The steam temperature is set to, for example, 120°C. The steam pressure is set to, for example, 150 kPa. By heating the water-containing crumbs with steam in the heating mechanism 71, the dewatering efficiency in the subsequent pressurizing mechanism 72 can be improved.

[0295] The water-containing crambs fed into the cramb supply section 70a are heated while being pushed downstream by the rotation of the rollers 71b (roller transport), and then transferred through the connecting section 73 into the chamber 72a of the pressurizing mechanism 72.

[0296] The pressurizing mechanism 72 includes a chamber 72a and a roller 72b for pressurizing the water-containing cramb, and a motor (not shown) that generates rotational power to rotate the roller 72b. The roller 72b is housed in the chamber 72a so as to extend in the direction of conveying the water-containing cramb. The shape of the roller 72b is not particularly limited, but for example, it is formed in a screw shape.

[0297] The upstream end of chamber 72a is connected to a connecting portion 73. The downstream end of chamber 72a is provided with a crumb discharge portion 70b for discharging the water-containing crumb that has been dewatered in chamber 72a.

[0298] The pressurizing mechanism 72 is configured such that a roller 72b compresses the water-containing crumb within the chamber 72a, squeezing out the moisture from the crumb. The roller 72b may be single or two or more. The water-containing crumb is pushed downstream as moisture is squeezed out by the pressurizing effect of the rotation of the roller 72b, and is discharged from the crumb discharge section 70b. The dewatered water-containing crumb, dewatered by the squeezer 70, is transferred to the crushing device 75. The water content of the dewatered water-containing crumb is usually 35% by mass or less, preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less.

[0299] (Crushing device 75) The crushing device 75 is configured to crush and pulverize the water-containing crumb transferred from the squeezer 70. The water-containing crumb discharged by the squeezer 70 after dewatering is uneven in size and shape. By crushing and pulverizing it in the crushing device 75, the drying efficiency in the subsequent drying process can be improved.

[0300] The crushing device 75 can be any device capable of crushing and pulverizing the crumb, such as a hammer-type crusher, cutter-type crusher, roller-type crusher, or pin mill. In particular, considering that it can efficiently and continuously crush water-containing crumb that has elasticity and viscosity, it is preferable to use a hammer-type crusher that crushes and pulverizes the water-containing crumb by the impact of a hammer rotated at high speed.

[0301] The water-containing crumb, crushed after dehydration, is dried in a drying process to become dried rubber. This dried rubber can be used, for example, as a bale of nitrile rubber in the production of hydrogenated nitrile rubber.

[0302] <Equipment Configuration of Hydrogenated Nitrile Rubber Manufacturing System> The equipment configuration of the hydrogenated nitrile rubber manufacturing system for producing hydrogenated nitrile rubber according to the present invention will be described below. Figures 2 and 3 show an example of the hydrogenated nitrile rubber manufacturing system in an embodiment of the present invention.

[0303] Figures 2 and 3 schematically illustrate the apparatus configuration of a hydrogenated nitrile rubber manufacturing system according to an embodiment of the present invention, in accordance with the manufacturing process. The hydrogenated nitrile rubber manufacturing system shown in Figures 2 and 3 is generally configured to include a crushing device 110, a dissolving device 120, a hydrogenation reactor 130, a solidification device 150, a screw-type twin-screw extruder dryer 160, a cooling device 170, a cutting device 180, and a packaging device 190.

[0304] (Crushing device 110) The crushing device 110 is configured to process nitrile rubber (dried rubber), which is the raw material for hydrogenated nitrile rubber, into a size suitable for subsequent processing.

[0305] The nitrile rubber used as the raw material for hydrogenated nitrile rubber is nitrile rubber manufactured using the nitrile rubber manufacturing system described above. For example, nitrile rubber bales (dried rubber bales) in which nitrile rubber is baled are used.

[0306] The crushing device 110 can be any device capable of cutting the nitrile rubber bale to a predetermined size, for example, an extruder-equipped cutter and a crusher can be used. Specifically, the nitrile rubber bale is set in the extruder-equipped cutter. The nitrile rubber bale is extruded through a die to form a specific shape (rod-shaped, sheet-shaped, tube-shaped, etc.), and then cut off at the exit of the die by a cutter, and further crushed into smaller pieces using a crusher. The raw nitrile rubber (base rubber) obtained by crushing with the crushing device 110 is transferred to the dissolution device 120 by a conveyor 111.

[0307] (Dissolving apparatus 120) The dissolving apparatus 120 is configured to perform the dissolving process. As shown in Figure 2, the dissolving apparatus 120 has a dissolving tank 121 for dissolving the base rubber in an organic solvent, a stirring device 122, and a heating device 125.

[0308] The dissolution tank 121 is formed, for example, in a closed cylindrical shape and is capable of storing the base rubber and organic solvent. The stirring device 122 includes a stirring blade 123 which is a member that is placed inside the dissolution tank 121 and rotates around a predetermined axis, a motor 124 that rotates the stirring blade 123, and a drive control unit (not shown) that controls the rotational number and speed of the stirring blade 123. The heating device 125 includes a heating device 126 that heats the inside of the dissolution tank 121, and a temperature control unit (not shown) that controls the temperature inside the dissolution tank 121.

[0309] The stirring device 122 is configured to rotate the stirring blades 123 at a predetermined rotational speed (stirring speed) within the dissolution tank 121, thereby dissolving the base rubber in the organic solvent by appropriately flowing the base rubber and the organic solvent. The stirring speed of the stirring blades 123, the shape and size of the stirring blades 123, the number of blades installed, etc., are appropriately determined considering the dissolution efficiency of the base rubber, etc.

[0310] The heating equipment 126 of the heating device 125 is configured to heat the molten liquid inside the molten tank 121 by sending a heat transfer medium to a jacket provided on the outer circumference of the molten tank 121, for example, through heat exchange.

[0311] In the dissolution apparatus 120, a predetermined amount of base rubber and organic solvent are placed in the dissolution tank 121, and the base rubber is dissolved by properly stirring with the stirring blade 123 for a predetermined time or longer (for example, 2 hours or more). This yields a solution in which the base rubber is dissolved in the organic solvent. The solution obtained from the dissolution apparatus 120 is transferred to the hydrogenation reactor 130.

[0312] (Hydrogenation Reactor 130) The hydrogenation reactor 130 is configured to perform the processes related to the hydrogenation step. As shown in Figure 2, the hydrogenation reactor 130 has a reaction tank (hydrogenation reaction tank) 131 for bringing nitrile rubber dissolved in an organic solvent into contact with hydrogen for a hydrogenation reaction, a stirring device 132, and a heating device 135.

[0313] The reaction tank 131 is formed, for example, in a closed cylindrical shape and is capable of storing the dissolved liquid transferred from the dissolution tank 121. The reaction tank 131 can also receive hydrogen from a hydrogen supply source 137 into the gas phase and a catalyst for the hydrogenation reaction from a catalyst supply source 138. The stirring device 132 includes a stirring blade 133, which is a member that rotates around a predetermined axis and is located inside the reaction tank 131, a motor 134 that rotates the stirring blade 133, and a drive control unit (not shown) that controls the rotational speed and rotational number of the stirring blade 133. The heating device 135 includes a heating device 136 that heats the inside of the reaction tank 131 and a temperature control unit (not shown) that controls the temperature inside the reaction tank 131.

[0314] The stirring device 132 is configured to rotate the stirring blades 133 at a predetermined rotational speed (stirring speed) within the reaction tank 131, thereby appropriately flowing the solution and bringing it into contact with and reacting with hydrogen in the gas phase. The stirring speed of the stirring blades 133, the shape and size of the stirring blades 133, the number of blades installed, etc., are appropriately determined considering the reaction efficiency, etc. For example, multiple stirring blades 133 may be placed at different height positions, in which case it is preferable that one of the stirring blades 133 be placed at a position that shears the gas-liquid interface between the hydrogen in the gas phase and the solution in the liquid phase within the reaction tank 131.

[0315] The heating equipment 136 of the heating device 135 is configured to send a heat transfer medium to a jacket provided on the outer circumference of the reaction tank 131, for example, and heat the solubility in the corresponding reaction tank 131 through heat exchange. The temperature inside the reaction tank 131 is preferably set to a temperature at which the hydrogenation reaction is effectively promoted, for example, to 150°C.

[0316] In the hydrogenation reactor 130, a solution of nitrile rubber dissolved in an organic solvent is placed in the reaction tank 131, a catalyst is added, and hydrogen is supplied until a predetermined pressure is reached, bringing the solution into contact with hydrogen to hydrogenate the nitrile rubber. The catalyst used is one that selectively hydrogenates only the carbon double bonds in the 1,3-butadiene polymerization units of the nitrile rubber polymer. Since the hydrogenation reaction takes place at the gas-liquid interface where gaseous hydrogen and liquid-phase solution come into contact, for example, by using a stirring blade 133 to flow the solution vertically, shearing the gas-liquid interface while refreshing the solution in contact with the gas phase, the contact efficiency of the nitrile rubber with hydrogen can be improved and the hydrogenation reaction can be promoted.

[0317] (Coagulation device 150) The coagulation device 150 is configured to perform the processing related to the coagulation process. The coagulation device 150 replaces the organic solvent in the solution with soft water (coagulation solution), which is a polar solvent, to solidify the hydrogenated nitrile rubber into a crumb shape. In this embodiment, in order to efficiently solidify the hydrogenated nitrile rubber, the coagulation device 150 has first and second coagulation tanks 151a and 151b. As shown in Figure 3, the two coagulation tanks, the first and second coagulation tanks 151a and 151b, are connected in series, but the number of coagulation tanks and the connection configuration are not particularly limited.

[0318] The first and second solidification tanks 151a and 151b are equipped with stirring devices 152a and 152b and a heating device 155a.

[0319] The stirring devices 152a and 152b are arranged inside each solidification tank and include stirring blades 153a and 153b, which are members that rotate around a predetermined axis, motors 154a and 154b that rotate the stirring blades 153a and 153b, and a drive control unit (not shown) that controls the rotational number and speed of the stirring blades 153a and 153b. The heating device 155a includes a heating unit 156a that heats the inside of the first solidification tank 151a, and a temperature control unit (not shown) that controls the temperature inside the first solidification tank 151a. Here, the heating device 155a is provided in the first solidification tank 151a for heating, but the second solidification tank 151b may be heated in the same way.

[0320] The solidification apparatus 150 is configured to rotate the stirring blades 153a and 153b at a predetermined rotational speed (stirring speed) within the first and second solidification tanks 151a and 151b, thereby enabling proper flow of the fluid contained within the first and second solidification tanks 151a and 151b. The stirring speed of the stirring blades 153a and 153b, the shape and size of the stirring blades 153a and 153b, the number of blades installed, etc., are determined appropriately considering the reaction conditions, etc.

[0321] The fluids in the first and second solidification tanks 151a and 151b are transported sequentially from upstream to downstream by pumps 157a and 157b as a cramb-containing fluid containing cramb-shaped solidified hydrogenated nitrile rubber and solidification liquid. Pump 157a transports the liquid in the first solidification tank 151a to the second solidification tank 151b. Pump 157b transports the liquid in the second solidification tank 151b to the screw-type twin-screw extruder dryer 160 via a dewatering machine 158. The transport by pumps 157a and 157b is controlled by a pump drive control unit (not shown).

[0322] The dissolved solution transferred from the hydrogenation reactor 130 to the solidification reactor 150 is continuously supplied into the first solidification tank 151a. Steam and water (soft water) are supplied to the first solidification tank 151a. The temperatures of the steam and water are adjusted so that the temperature inside the first solidification tank 151a is above the boiling point of the organic solvent. As the dissolved solution is stirred in the first solidification tank 151a, the organic solvent vaporizes (evaporates) and is replaced by highly polar water, causing the hydrogenated nitrile rubber in the organic solvent to precipitate.

[0323] Similarly, in the second solidification tank 151b, stirring the liquid inside the second solidification tank 151b promotes the vaporization of the organic solvent, causing hydrogenated nitrile rubber to precipitate from the organic solvent. The liquid discharged from the second solidification tank 151b is in the form of a crumb-containing slurry, in which the organic solvent has vaporized and crumb-shaped hydrogenated nitrile rubber is suspended in the liquid (water).

[0324] The solidification apparatus 150 is configured to precipitate and solidify the hydrogenated nitrile rubber dissolved in the solution as a solid by stirring the solution in an environment above the boiling point of the organic solvent, vaporizing the organic solvent, and replacing it with water, in which the hydrogenated nitrile rubber is insoluble.

[0325] As shown in Figure 3, a dewatering machine 158 is positioned between the solidification device 150 and the screw-type twin-screw extruder dryer 160. The dewatering machine 158 is configured to separate the water-containing crumb from the slurry. A screen, wire mesh, electric sieve, etc., can be used for the dewatering machine 158.

[0326] (Screw-type twin-screw extruder dryer 160) The screw-type twin-screw extruder dryer 160 is configured to perform processes related to the dewatering and drying process. The screw-type twin-screw extruder dryer 160 dewaters and dries the water-containing crumb, and also molds the dried hydrogenated nitrile rubber into a predetermined shape and discharges it, and is configured to also perform processes related to part of the molding process.

[0327] Although the screw-type twin-screw extruder dryer 160 is designed to perform the dewatering and drying processes continuously, the dewatering and drying processes may be performed using different devices. For example, a squeezer may be used as the dewatering machine for the dewatering process, and a hot air dryer, vacuum dryer, expander dryer, kneader dryer, etc. may be used as the dryer for the drying process.

[0328] The screw-type twin-screw extruder dryer 160 in this embodiment has a barrel unit that dewaters and dries hydrogenated nitrile rubber while conveying it. The barrel unit has a supply barrel section 161 that supplies water-containing crumb into the barrel unit from the upstream side to the downstream side, a dewatering barrel section 162 that functions as a dewaterer, and a drying barrel section 163 that functions as a dryer. Furthermore, a die section 164 is provided at the downstream end of the barrel unit that molds the hydrogenated nitrile rubber into a predetermined shape and discharges it.

[0329] The supply barrel section 161, the dewatering barrel section 162, and the drying barrel section 163 may each be configured by connecting multiple barrels. That is, the barrel unit may be composed of multiple barrels connected from the upstream side to the downstream side. The number of barrels that make up the supply barrel section 161, the dewatering barrel section 162, and the drying barrel section 163 is not particularly limited and can be set to a number according to the water content of the hydrogenated nitrile rubber, etc.

[0330] The supply barrel section 161 is the region that supplies the water-containing crumb, which has been transferred from the solidification device 150 via the dewatering machine 158, into the barrel unit. The barrels constituting the supply barrel section 161 have feed ports that supply the water-containing crumb into the barrel unit.

[0331] The dewatering barrel section 162 is a region that separates and discharges moisture (ceramic water) from the hydrogenated nitrile rubber. In the dewatering barrel section 162, the moisture contained in the hydrogenated nitrile rubber is discharged in liquid form (wastewater) and vapor form (exhaust steam). The barrels constituting the dewatering barrel section 162 have dewatering slits that discharge the moisture contained in the hydrogenated nitrile rubber to the outside as wastewater or exhaust steam. Which dewatering barrel discharges the moisture as wastewater or exhaust steam can be set as appropriate.

[0332] The drying barrel section 163 is a region where the hydrogenated nitrile rubber, after dewatering in the dewatering barrel section 162, is dried under reduced pressure. The barrels constituting the drying barrel section 163 have vents for degassing. Vent piping is connected to each vent, and a vacuum pump is connected to the vent piping. The operation of the vacuum pump reduces the pressure inside the drying barrel section 163 to a predetermined level. The degree of pressure reduction in the drying barrel section 163 is appropriately controlled by the pressure control unit. The hydrogenated nitrile rubber is melted and kneaded under reduced pressure in the drying barrel section, thereby removing any air it contains.

[0333] The die section 164 is a processing mold section located at the downstream end of the barrel unit and has an outlet with a predetermined nozzle shape. The hydrogenated nitrile rubber, dried via the drying barrel section 163, passes through the outlet of the die section 164 and is extruded into a shape corresponding to the predetermined nozzle shape. The hydrogenated nitrile rubber passing through the die section 164 can be molded into various shapes such as granular, columnar, round rod, or sheet, depending on the nozzle shape of the die section 164. In this embodiment, the nozzle shape of the die section 164 is formed in a horizontally elongated, approximately rectangular shape, and the hydrogenated nitrile rubber passing through the die section 164 is molded into a sheet. The sheet-shaped hydrogenated nitrile rubber is molded to a width of approximately 20 to 60 cm and a height of approximately 2 to 10 cm and extruded from the die section 164. A breaker plate or wire mesh may also be provided between the tip of the screw and the die section 164.

[0334] The barrels constituting the dewatering barrel section 162 and the barrels constituting the drying barrel section 163 are heated. The heating method is not particularly limited, but for example, it is preferable to supply high-temperature steam from a steam supply means to the steam flow jacket formed in each barrel. Each barrel may be heated at a different set temperature, or at the same set temperature. The hydrogenated nitrile rubber extruded and conveyed downstream by the screw becomes under high pressure and at a high temperature downstream. The temperature of the hydrogenated nitrile rubber discharged from the die section 164 is, for example, about 200°C.

[0335] The screw-type twin-screw extruder dryer 160 has a pair of screws inside the barrel unit. The pair of screws extends from the upstream side to the downstream side inside the barrel unit. The pair of screws are rotationally driven by a screw drive unit 165 such as a motor. This allows the water-containing crumb supplied from the feed port to the supply barrel section 161 to be conveyed downstream while being mixed. As the screws rotate, the water-containing crumb is plasticized and mixed to become a molten mixture (molten kneaded material), which is then conveyed downstream while being dewatered and dried, and discharged from the die section 164.

[0336] Preferably, the pair of screws are of the biaxial meshing type, where the peaks and valleys of each screw mesh with each other, thereby improving the dewatering and drying efficiency of hydrogenated nitrile rubber. The pair of screws may rotate in the same direction or in different directions, but it is preferable to rotate them in the same direction to take into consideration the self-cleaning performance.

[0337] The screw shape (flight shape) of the pair of screws is not particularly limited, but it is preferable to select a shape that can effectively bring out the function of each barrel. For example, to promote heat generation by shear, shapes such as half-angle flights or forward flights may be used. In addition, kneading discs with cross-sectional shapes such as pseudo-elliptical, oval, or truncated triangular shapes may be provided in the regions corresponding to the dewatering barrel section 162 and the drying barrel section 163.

[0338] The water-containing crumb, transferred from the solidification device 150 via the dewatering machine 158, is supplied to the supply barrel section 161 through the feed port. The hydrogenated nitrile rubber supplied to the supply barrel section 161 is sent from the supply barrel section 161 to the dewatering barrel section 162 by the rotation of a pair of screws located inside the barrel unit. In the dewatering barrel section 162, water is squeezed out of the molten hydrogenated nitrile rubber and discharged as wastewater or exhaust steam.

[0339] The hydrogenated nitrile rubber, dewatered in the dewatering barrel section 162, is sent from the dewatering barrel section 162 to the drying barrel section 163 by the rotation of a pair of screws in the barrel unit. The molten hydrogenated nitrile rubber is carried downstream in the drying barrel section 163, generating heat and increasing in temperature. In the drying barrel section 163, the water contained in the molten hydrogenated nitrile rubber vaporizes, and this water is discharged to the outside as exhaust steam through a vent pipe connected to a vent port. After passing through the drying barrel section 163, the hydrogenated nitrile rubber becomes a dry molten material, which is supplied to the die section 164 by the rotation of a pair of screws in the barrel unit, and extruded from the die section 164 into a predetermined shape (for example, a sheet).

[0340] The operating conditions of the screw-type twin-screw extruder dryer 160 can be appropriately selected according to the characteristics of the hydrogenated nitrile rubber being manufactured. Examples of operating conditions for the screw-type twin-screw extruder dryer 160 include the screw rotation speed (N) and extrusion rate (Q), the ratio of extrusion rate (Q) to rotation speed (N) (Q / N), the screw's maximum torque, specific power, specific power, shear rate, etc.

[0341] The sheet-like hydrogenated nitrile rubber discharged from the die section 164 of the screw-type twin-screw extruder dryer 160 at a predetermined extrusion speed is conveyed to the cooling device 170 in a continuous strip-like state in the discharge direction. The water content of the hydrogenated nitrile rubber dried in the screw-type twin-screw extruder dryer 160 is less than 1% by weight.

[0342] The sheet-like hydrogenated nitrile rubber extruded from the die section 164 of the screw-type twin-screw extruder dryer 160 is transported in a continuous strip-like state from the die section 164 of the screw-type twin-screw extruder dryer 160 through the cooling device 170 to the cutting device 180.

[0343] (Cooling device 170) The cooling device 170 is configured to perform processing related to the cooling process. Examples of cooling methods for the cooling device 170 include a water cooling method in which cooling water is sprayed or the device is immersed in water, an air cooling method in which cooling air is blown on, and a method in which the device is left at room temperature. In this embodiment, the cooling device 170 has a shower device 171 that sprays cooling water onto a sheet of hydrogenated nitrile rubber, and a transport-type cooling device 173 that blows cooling air while transporting the sheet of hydrogenated nitrile rubber. By drying in the order of water cooling followed by air cooling, it is preferable to obtain a sheet of hydrogenated nitrile rubber with a water content of less than 1% by mass in a short time.

[0344] The shower device 171 is positioned close to the die section 164 of the screw-type twin-screw extruder dryer 160 and is configured to cool the sheet-shaped hydrogenated nitrile rubber immediately after it is discharged from the die section 164 by spraying it with cooling water in a shower-like manner. The sheet-shaped hydrogenated nitrile rubber, to which the cooling water has been sprayed, is transported to a transport-type cooling device 173 by a roller conveyor 172 (not shown in detail) having transport rollers. The roller conveyor 172 may be, for example, a cooling transport pipe formed in the shape of a tube for cooling the sheet-shaped hydrogenated nitrile rubber.

[0345] As shown in Figure 3, the conveyor-type cooling device 173 has a configuration in which a conveyor 174 for conveying sheet-shaped hydrogenated nitrile rubber and a cooling means 175 for sending out cooling air are arranged in an air cooling tank 176. The device is configured to cool the sheet-shaped hydrogenated nitrile rubber by blowing cooling air from the cooling means 175 while it is being conveyed by the conveyor 174. The sheet-shaped hydrogenated nitrile rubber cooled in the conveyor-type cooling device 173 is then conveyed to a cutting device 180 located downstream.

[0346] The conveying surface of the conveyor belt 174 is made of a non-adhesive material that prevents the sheet-like hydrogenated nitrile rubber from sticking. In addition, a horizontal air duct 177 may be provided at least one end of the conveyor belt 174 to supply cooling air into the air cooling tank 176.

[0347] The conveying speed of the sheet-shaped hydrogenated nitrile rubber by the conveyor belt 174 is approximately the same as the discharge speed of the sheet-shaped hydrogenated nitrile rubber discharged from the die section 164 of the screw-type twin-screw extruder dryer 160. The length of the conveyor belt 174, the length of the cooling means 175 (the range over which cooling air is blown), and the cooling time (cooling speed) are appropriately set according to the target cooling temperature of the sheet-shaped hydrogenated nitrile rubber discharged from the conveyor-type cooling device 173. The target cooling temperature is set to, for example, 40°C or lower, which makes it possible to easily and stably cut the sheet-shaped hydrogenated nitrile rubber in a subsequent stage.

[0348] The conveying cooling device 173 may be configured to convey sheet-shaped hydrogenated nitrile rubber by folding it back and forth on a multi-stage conveyor with multiple rollers or rod-shaped slats. In this case, the sheet-shaped hydrogenated nitrile rubber discharged from the die section 164 of the screw-type twin-screw extruder dryer 160 is conveyed by descending one stage at a time from the top stage of the conveyor constituting the conveying conveyor 174. Cooling air is blown onto each stage of the conveyor from the upper side (the upper surface side of the sheet-shaped hydrogenated nitrile rubber).

[0349] When the conveying conveyor 174 is configured with multiple upper and lower conveyors and the material is transported in a folded manner, the sheet-like hydrogenated nitrile rubber can be transported with each stage inverted. By blowing cooling air onto each stage conveyor from the upper side (top side), both sides of the sheet-like hydrogenated nitrile rubber can be cooled uniformly and reliably. In addition, each folded section can be made into a free-shrinking section, allowing the sheet-like hydrogenated nitrile rubber to shrink with ample margin in that free-shrinking section.

[0350] (Cutting device 180) The sheet-shaped hydrogenated nitrile rubber is connected in a strip-like manner from the die section 164 of the screw-type twin-screw extruder dryer 160 through the conveying cooling device 173 to the cutting device 180. The cutting device 180 is configured to cut the sheet-shaped hydrogenated nitrile rubber to process it into cut sheet-shaped hydrogenated nitrile rubber, and has a clamper 181 that supports the leading edge of the sheet-shaped hydrogenated nitrile rubber, and a cutter 182 that is vertically movable on the upper surface of the sheet-shaped hydrogenated nitrile rubber. The cutting blade of the cutter 182 is positioned to be approximately perpendicular to the upper surface of the sheet-shaped hydrogenated nitrile rubber.

[0351] The leading edge of the sheet-like hydrogenated nitrile rubber that reaches the cutting table of the cutting device 180 is held stably by the clamper 181 and cut to a predetermined length by the cutter 182 to produce a cut sheet of hydrogenated nitrile rubber. The timing for raising and lowering the cutter 182 is controlled by a cutter control unit (not shown). The cutter control unit may raise and lower the cutter 182 by detecting the length (feed amount) of the sheet-like hydrogenated nitrile rubber conveyed onto the cutting table, or it may raise and lower the cutter 182 in synchronization with the conveying speed (feed speed) of the sheet-like hydrogenated nitrile rubber.

[0352] The cut sheets of hydrogenated nitrile rubber produced by the cutting device 180 are transported to the vicinity of the workbench 183, where they are stacked. The stacked cut sheets of hydrogenated nitrile rubber adhere to each other due to their own weight, becoming a single block (dry rubber bale) in the form of a solid (bale-like) mass.

[0353] The cut sheet-like hydrogenated nitrile rubber on the workbench 183 is weighed by a weighing cell and adjusted to produce 25 kg dry rubber bales. The produced dry rubber bales are transferred to the packaging device 190 by a roller conveyor 185.

[0354] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. In the following description, "%", "ppm", and "parts" used to express quantities refer to mass unless otherwise specified.

[0355] Furthermore, in polymers produced by copolymerizing multiple types of monomers, the proportion of a monomer unit formed by polymerizing a certain monomer in the polymer is, unless otherwise specified, usually equal to the ratio (starting ratio) of that particular monomer to the total monomers used in the polymerization of the polymer.

[0356] In the examples, reference examples, and comparative examples, various measurements and evaluations were carried out according to the following methods.

[0357] <Water-containing crumb diameter> The water-containing crumbs produced by the coagulation reaction were classified using a JIS classification sieve. After that, each classified water-containing crumb was dried in a hot air dryer at 80°C for 3 hours, and the mass was measured to determine the ratio of each crumb diameter mass (a) to (h). The JIS sieve conformed to the provisions of the Japanese Industrial Standard (JIS Z8801-1). (a) Does not pass through a JIS sieve with a mesh size of 9.5 mm, (b) Passes through a JIS sieve with a mesh size of 9.5 mm but does not pass through a JIS sieve with a mesh size of 8.0 mm, (c) Passes through a JIS sieve with a mesh size of 8.0 mm but does not pass through a JIS sieve with a mesh size of 4.75 mm, (d) Passes through a JIS sieve with a mesh size of 4.75 mm but does not pass through a JIS sieve with a mesh size of 3.35 mm, (e) Passes through a JIS sieve with a mesh size of 3.35 mm but does not pass through a JIS sieve with a mesh size of 2.36 mm, (f) Passes through a JIS sieve with a mesh size of 2.36 mm but does not pass through a JIS sieve with a mesh size of 1.7 mm, (g) Passes through a JIS sieve with a mesh size of 1.7 mm but does not pass through a JIS sieve with a mesh size of 0.43 mm, (h) Passes through a JIS sieve with a mesh size of 0.43 mm.

[0358] <Moisture Content of Hydrated Crumb> The moisture content of the hydrated crumb produced by the coagulation reaction after dehydration was determined according to the "oven method" specified in JIS K6238-1. Specifically, 10 g of hydrated crumb was placed in an oven at 105 ± 5°C and dried until the mass no longer changed substantially. The amount of mass loss before and after drying was determined, and the ratio of the mass loss to the mass of the crumb after drying was calculated as the moisture content.

[0359] <Repeating Units> The acrylonitrile polymerization units and 1,3-butadiene polymerization units (the sum of 1,2-bonding units, 1,4-bonding units, and their hydride units) in hydrogenated nitrile rubber are, １ The intensity ratio of the peaks originating from each repeating unit was determined using 1H-NMR (nuclear magnetic resonance) spectroscopy, and the content ratio in the polymer was determined by converting this to a mass ratio.

[0360] The proportion of 1,2-bonding units in the 1,3-butadiene polymerization units of hydrogenated nitrile rubber is: １Using 1H-NMR (nuclear magnetic resonance) spectroscopy, peak intensities originating from 1,2-bonding units, 1,4-bonding units, and their hydride units were determined, and the ratio of (total amount of 1,2-bonding units and their hydride units) / (total amount of 1,2-bonding units, 1,4-bonding units, and their hydride units) was calculated.

[0361] <Iodine Value> The iodine value of hydrogenated nitrile rubber was measured in accordance with JIS K6235.

[0362] <THF Molecular Weight> The weight-average molecular weight (Mw), Z-average molecular weight (Mz), and molecular weight distribution (Mz / Mw) of hydrogenated nitrile rubber were measured by gel permeation chromatography (GPC) using a tetrahydrofuran (THF) solution under the following measurement conditions: • Separation column: TSK-gel SuperHM-H (Tosoh Corporation) • Detector: Differential refractometer detector RID-10A (Shimadzu Corporation) • Eluent flow rate: 0.6 mL / min • Column temperature: 40°C • Standard polymer: TSK Standard Polystyrene (Tosoh Corporation)

[0363] <NMP Molecular Weight> The weight-average molecular weight (Mw) of hydrogenated nitrile rubber was measured by gel permeation chromatography (GPC) using an NMP solution under the following measurement conditions: • Separation column: Shodex KD-806M (Showa Denko K.K.) • Detector: Differential refractometer detector RID-10A (Shimadzu Corporation) • Eluent flow rate: 0.3 mL / min • Column temperature: 40°C • Standard polymer: TSK standard polystyrene (Tosoh Corporation)

[0364] <Polymer pH> 10 g of NMP solution (solid content concentration: 8%) of hydrogenated nitrile rubber or hydrogenated nitrile rubber bale was mixed with 90 g of deionized water. The mixture was stirred and pressed with a spatula, and the liquid contained within the solidified hydrogenated nitrile rubber was extracted in the deionized water phase to obtain an extract. The pH of the extract was measured at 25°C in accordance with JIS Z8802 (2011).

[0365] <Anti-aging agent content> Hydrogenated nitrile rubber or a hydrogenated nitrile rubber bale is dissolved in a chlorobenzene solution, analyzed by gas chromatography, to determine the content ratio of the anti-aging agent (BHT) based on the total mass of the polymer.

[0366] <Bulk specific gravity> A hydrogenated nitrile rubber or a hydrogenated nitrile rubber bale is cut into a size of approximately 2 cm×3 cm×0.2 cm, and the bulk specific gravity (g / cm ３ ) is measured using an automatic hydrometer (manufactured by Toyo Seiki Seisaku-sho, Ltd., product name: "DSG-1").

[0367] <Particle size distribution of polymer: D90 / D10, D50 / D10> After dissolving hydrogenated nitrile rubber or a hydrogenated nitrile rubber bale in N-methylpyrrolidone (NMP), the solid content concentration is adjusted to 0.3%, followed by stirring at 60 rpm for 30 minutes or longer until dissolution is confirmed, to obtain an NMP solution as a measurement object. For the obtained NMP solution, under the condition of 25°C, using a dynamic light scattering measuring apparatus (manufactured by Otsuka Electronics Co., Ltd., ELSZ-2000S), the particle diameter D10 when 10% of the total volume exists, the particle diameter when 50% of the total volume exists: median diameter D50, and the particle diameter D90 when 90% of the total volume exists, which are volume-based particle size distribution parameters, are measured, and D50 / D10 and D90 / D10 are calculated.

[0368] <Water content of polymer> The water content of hydrogenated nitrile rubber and hydrogenated nitrile rubber bales was measured in accordance with the "oven method" specified in JIS K6238-1.

[0369] <Ash content> The ash content contained in hydrogenated nitrile rubber and hydrogenated nitrile rubber bales was measured in accordance with JIS K6228 A method.

[0370] <Content of ash components> The content of each component in the ash was obtained by pressing the ash collected in the above ash content measurement onto a Φ20 mm titration filter paper, and performing XRF measurement using ZSXPrimus (manufactured by Rigaku Corporation).

[0371] <Long-term storage stability of positive electrode binder> The positive electrode binders obtained in the examples, reference examples, and comparative examples were stored at 25°C for 3 months, then 500 mL was passed through a 200-mesh wire mesh (wire diameter 0.05 mm) and dried at 105°C for 1 hour. The amount of aggregates (%) contained in the positive electrode binder was then calculated using the following formula: Amount of aggregates (%) = (Mass of wire mesh after drying - Mass of wire mesh before sample passage) / (Mass of positive electrode binder × Solid content concentration of positive electrode binder (%) / 100) × 100 The calculated amount of aggregates was evaluated according to the following criteria. Note that the lower the amount of aggregates, the better the positive electrode binder's resistance to aggregation. ◎: Amount of aggregates less than 0.05% 〇: Amount of aggregates 0.05% or more and less than 0.1% △: Amount of aggregates 0.1% or more and less than 0.5% ×: Amount of aggregates 0.5% or more

[0372] <Dispersibility of Conductive Material Dispersions> For the conductive material dispersions obtained in the examples, reference examples, and comparative examples, the viscosity was measured for 120 seconds at a temperature of 25°C and a shear rate of 10 (1 / s) using a rheometer (Anton Paar, "MCR302"). An index was calculated based on the average viscosity measurement value from 61 seconds to 120 seconds, with Comparative Example 1 set to 100, and evaluated according to the following criteria. A smaller index of the dispersion viscosity indicates better dispersibility. ◎: 85 or less ○: Greater than 85 and 90 or less △: Greater than 90 and 95 or less ×: Greater than 95

[0373] <Stability of Conductive Material Dispersion Viscosity> The conductive material dispersions obtained in the Examples, Reference Examples, and Comparative Examples were measured for viscosity (η0) and then stored in a sealed container at 25°C for 10 days. After that, the viscosity of the dispersion was measured again (η1), and the viscosity change rate was calculated. The viscosity retention rate Δη = η1 / η0 × 100 (%) of the conductive material dispersion before and after storage was calculated, and an index was determined with Comparative Example 1 set to 100. The viscosity stability of the conductive material dispersion was evaluated according to the following criteria. A smaller index of viscosity retention rate Δη indicates that the conductive material dispersion has superior viscosity stability. ◎: Less than 90 〇: 90 or more and less than 94 △: 94 or more and less than 98 ×: 98 or more and less than 110 ××: 110 or more

[0374] <Peel Strength> The positive electrodes prepared in the examples, reference examples, and comparative examples were cut into rectangles with a length of 100 mm and a width of 10 mm to serve as test pieces. Cellophane tape (compliant with JIS Z1522) was attached to the surface of the positive electrode composite layer with the side containing the positive electrode composite layer facing downwards. The stress was measured when the tape was peeled off by pulling one end of the current collector vertically at a speed of 100 mm / min (the cellophane tape was fixed to the test stand). Three measurements were taken, and an index was calculated based on the average value, with Comparative Example 2 set to 100. The results were then evaluated according to the following criteria. A higher peel strength index indicates that the positive electrode composite layer is more firmly adhered to the current collector made of aluminum foil. ◎: 150 or more ○: 130 or more and less than 150 △: 110 or more and less than 130 ×: Less than 110

[0375] <Flexibility> The positive electrodes prepared in the examples, reference examples, and comparative examples were wrapped around a stainless steel cylinder with a diameter of 2.5 mm (with the current collector on the inside). The presence or absence of crack formation on the surface of the positive electrode composite layer after wrapping was visually confirmed. If no crack formation was confirmed, the diameter of the stainless steel cylinder was successively reduced to 2.0 mm and then 1.5 mm, and the same procedure was performed. The diameter of the cylinder at which the first crack was confirmed on the surface of the positive electrode composite layer (cylinder diameter at the time of crack formation) was recorded and evaluated according to the following criteria. A smaller cylinder diameter at the time of crack formation indicates superior flexibility of the positive electrode, and if no cracks are formed even when using a cylinder with a diameter of 1.5 mm, it indicates that the positive electrode has extremely superior flexibility. ◎: No crack formation was confirmed even with a cylinder diameter of 1.5 mm. ○: Cylinder diameter at the time of crack formation is 1.5 mm △: Cylinder diameter at the time of crack formation is 2.0 mm ×: Cylinder diameter at the time of crack formation is 2.5 mm

[0376] <Warpage Characteristics> The positive electrodes prepared in the examples, reference examples, and comparative examples were cut into strips with dimensions of 2 cm in width (coating width direction) and 5 cm in length (coating direction) to form test specimens. These test specimens were placed on a horizontal surface with the positive electrode composite layer side facing downwards. When the center of the width direction of the two ends of the length direction of the test specimen was pressed down from above onto the horizontal surface, the height of the width direction end of the test specimen from the horizontal surface (amount of warpage) was measured using a displacement laser (Keyence Corporation "LJV-7080"). An index was calculated with Comparative Example 1 set to 100, and evaluated according to the following criteria. A smaller index of warpage indicates that the warpage of the positive electrode is suppressed. ◎: 105 or less ○: Greater than 105 and 110 or less △: Greater than 110 and 115 or less ×: Greater than 115, or the positive electrode composite layer cracked.

[0377] <Capacity Characteristics> The lithium-ion secondary batteries prepared in the Examples, Reference Examples, and Comparative Examples were left to stand at 25°C for 5 hours after electrolyte injection. Next, they were charged to a cell voltage of 3.65V using a constant current method at 25°C and 0.2C (where C is a value expressed as rated capacity (mA) / 1h (hour)), and then aged at 60°C for 12 hours. Then, they were discharged to a cell voltage of 3.00V using a constant current method at 25°C and 0.2C. After that, CC-CV charging (upper limit cell voltage 4.35V) was performed using a constant current method of 0.2C, and CC discharge was performed to 3.00V using a constant current method of 0.2C. This charging and discharging at 0.2C was repeated three times. The discharge capacity of this third discharge was taken as the initial capacity, and the value of initial capacity / theoretical capacity was calculated, an index was obtained with Comparative Example 1 set to 100, and it was evaluated according to the following criteria. A larger initial capacity / theoretical capacity index indicates a higher initial discharge capacity of the lithium-ion secondary battery. ◎: 120 or more 〇: 115 or more and less than 120 〇~△: 110 or more and less than 115 △: 105 or more and less than 110 ×: 102 or more and less than 105 ××: less than 102

[0378] <Resistivity Characteristics> For the positive electrodes prepared in the Examples, Reference Examples, and Comparative Examples, the resistivity (Ω・cm) at the interface between the positive electrode composite layer and the current collector was measured at 25°C using an electrode resistance system (HIOKI E.E. CORPORATION "RM2610"). ２The resistivity was measured, and an index was calculated with Comparative Example 1 set to 100. The following criteria were used for evaluation. A smaller resistivity index indicates better performance. ◎: 150 or less ○: Over 150 and 300 or less △: Over 300 and 500 or less ×: Over 500

[0379] <Cycle Characteristics> The lithium-ion secondary batteries prepared in the Examples, Reference Examples, and Comparative Examples were left standing at 25°C for 5 hours after electrolyte injection. Next, they were charged to a cell voltage of 3.65V using a constant current method at 25°C and 0.2C, and then aged at 60°C for 12 hours. Then, they were discharged to a cell voltage of 3.00V using a constant current method at 25°C and 0.2C. After that, CC-CV charging (upper limit cell voltage 4.35V) was performed using a constant current method at 0.2C, and CC discharge was performed to 3.00V using a constant current method at 0.2C. This 0.2C charge-discharge process was repeated three times. Next, under conditions of 45°C, the charge-discharge operation was performed 300 times with a cell voltage of 4.35-3.00V and a charge-discharge rate of 1.0C. At that time, the discharge capacity of the first cycle was defined as X1, and the discharge capacity of the 300th cycle was defined as X2. Using the discharge capacities X1 and X2, the capacity retention rate was calculated as (X2 / X1) × 100 (%), and an index was determined with Comparative Example 1 set to 100. The evaluation was then performed according to the following criteria. A higher capacity retention rate index indicates that the lithium-ion secondary battery has superior cycle characteristics. ◎: 95 or higher ○: 90 or higher and less than 95 ○ to △: 85 or higher and less than 90 △: 80 or higher and less than 85 ×: Less than 80

[0380] <High-Temperature Storage Characteristics> The lithium-ion secondary batteries prepared in the Examples, Reference Examples, and Comparative Examples were left standing at 25°C for 5 hours after electrolyte injection. Next, they were charged to a cell voltage of 3.65V using a constant current method at 25°C and 0.2C, and then aged at 60°C for 12 hours. Then, they were discharged to a cell voltage of 3.00V using a constant current method at 25°C and 0.2C. After that, CC-CV charging (upper limit cell voltage 4.35V) was performed using a constant current method at 0.2C, and CC discharge was performed to 3.00V using a constant current method at 0.2C. This charging and discharging at 0.2C was repeated three times. Next, the initial IV resistance R1 was measured. Specifically, the lithium-ion secondary battery was charged to 50% of its State of Charge (SOC) at 1.0C in a 25°C atmosphere. Then, charging and discharging were performed for 20 seconds at 0.5C, 1.0C, 1.5C, and 2.0C, centered around 50% of the SOC. In each case (charging and discharging), the battery voltage after 20 seconds was plotted against the current value, and the slope was determined as the initial IV resistance R1 (Ω) (IV resistance during charging and IV resistance during discharging). Subsequently, CC-CV charging (upper limit cell voltage 4.35V) was performed at a constant current of 0.2C. Next, the lithium-ion secondary battery was stored for 4 weeks in an inert oven with a nitrogen atmosphere at 80°C. After storage, the IV resistance R2 after high-temperature storage was measured in the same way as the initial IV resistance R1. Using the obtained initial IV resistance R1 and the IV resistance R2 after high-temperature storage, the IV resistance increase rate was calculated using the following formula. IV resistance increase rate (%) = (R2 - R1) / R1 × 100 An index was calculated for this IV resistance increase rate (%), with Comparative Example 1 set to 100, and evaluated according to the following criteria. A smaller index for the IV resistance increase rate (%) indicates that the internal resistance has been reduced over a long period, and that the battery characteristics of the lithium-ion secondary battery are superior. ◎: Less than 70 ◎~〇: 70 or more and less than 75 〇: 75 or more and less than 80 〇~△: 80 or more and less than 85 △: 85 or more and less than 90 △~×: 90 or more and less than 93 ×: 93 or more and less than 95 ××: 95 or more

[0381] (Example 1) <Production of Nitrile Rubber> In a reactor with an internal volume of 10 liters, 100 parts of ion-exchanged water, 35 parts of acrylonitrile, and 65 parts of 1,3-butadiene were charged. 40 parts of a 10% aqueous solution of sodium dodecylbenzenesulfonate were added as an emulsifier, 0.1 parts of potassium phosphate as a stabilizer, and 0.26 parts of tert-dodecyl mercaptan (TDM) as a molecular weight modifier (chain transfer agent). 0.1 parts of cumene hydroperoxide (QHPO) as a polymerization initiator, appropriate amounts of reducing agent, and chelating agent were added, and emulsion polymerization was carried out at a temperature of 20°C to copolymerize acrylonitrile and 1,3-butadiene. When the polymerization conversion rate reached 85%, 0.2 parts of hydroxylamine sulfate per 100 parts of monomer was added to stop the polymerization. Next, the mixture was heated and steam distilled at approximately 90°C under reduced pressure to recover the residual monomers. Then, 0.1 parts of dibutylhydroxytoluene (BHT), a phenolic antioxidant, was added to obtain the polymerization solution. The polymerization solution was adjusted to pH 5.5 using a pH buffer.

[0382] In a solidification tank equipped with a thermometer and a central stirring blade device, 100 parts of the polymer solids from the obtained polymerization liquid were directly added to a 25% calcium chloride aqueous solution (4 parts as calcium chloride) heated to 45°C and vigorously stirred (600 rpm, peripheral speed 3.1 m / s). The polymer was then solidified by continuously rotating stirring blades (central part) to obtain a water-containing crumb. The obtained water-containing crumb was measured for each component using a JIS classification sieve, and the results are shown in Table 1. Note that Tables 1-1 to 1-4 below are divisions of a single table, and Tables 1-1 to 1-4 together are referred to as Table 1.

[0383] Next, the filtered water-containing crumb was added to a washing tank equipped with a stirring device and filled with ion-exchanged water at 45°C. The water-containing crumb was washed by passing 50 times the amount of ion-exchanged water (45°C) relative to the polymer while stirring. The washed water-containing crumb was heated to 60°C, then dehydrated at over 100°C using a steam-injected squeezer until the water content was reduced to 5%, and then dried under reduced pressure at 90°C to obtain nitrile rubber A.

[0384] <Hydrogenation of Nitrile Rubber> (Hydrogenation Reaction) Next, 9 parts of the obtained nitrile rubber A and 141 parts of monochlorobenzene, a halogenated hydrocarbon, were dissolved and added to the reactor. Thereafter, while continuing to stir, the reactor was heated to 0.7 MPa H ２ The mixture was degassed three times. Then, 2 L of a monochlorobenzene solution containing bis(tricyclohexylphosphine)benzylideneruthenium dichloride was added as a Grubbs catalyst so that the amount of Grubbs catalyst relative to the polymer was 2000 ppm. The temperature was then raised to 150°C, and the hydrogenation reaction was carried out under a hydrogen pressure (gauge pressure) of 8.4 MPa until the iodine value of the polymer reached 13 mg / 100 mg. During the reaction, the temperature was kept constant using a cooling coil connected to a temperature control device and a thermal sensor.

[0385] (Catalyst Removal Process) After the hydrogenation reaction was complete, in order to remove the ruthenium catalyst, one part of aminopropyl group-modified silica (product name "QuadraSil AP", manufactured by SIGMA-ALDRICH, silica with aminopropyl groups introduced on its surface, average particle size 54 μm) was added to the reactor and stirred for 30 minutes. The mixture was then filtered through a 5 μm pore size filter.

[0386] (Recovery of sheet-like hydrogenated nitrile rubber using a screw-type twin-screw extruder) After the catalyst removal described above, a large amount of steam was introduced into the filtered monochlorobenzene solution containing hydrogenated nitrile rubber to isolate the water-containing crumb. Next, the isolated water-containing crumb was dehydrated and dried using a screw-type twin-screw extruder (TEX44αII: manufactured by Japan Steel Works Co., Ltd.) which has a reduced-pressure drying barrel and a roughly rectangular die section, to extrude a sheet-like dried rubber (width 300 mm x thickness 30 mm) and obtain hydrogenated nitrile rubber A.

[0387] The repeating unit ratio, molecular weight, molecular weight distribution, particle size distribution, iodine value, antioxidant content, water content, bulk density, polymer pH, and ash content of the obtained sheet-like hydrogenated nitrile rubber A were measured and are shown in Table 2. In addition, the sodium (Na), potassium (K), calcium (Ca), sulfur (S), chlorine (Cl), palladium (Pd), ruthenium (Ru), rhodium (Rh), and phosphorus (P) content in the ash were measured, and the ratio of the total amount of sodium (Na) and potassium (K) (Na+K) to the total ash, the ratio of the total amount of calcium (Ca) and sulfur (S) (Ca+S) to the total ash, and the ratio of the total amount of sodium (Na) and potassium (K) (Na+K) to calcium content were measured. The mass ratio of the total amount of sodium (Ca) to the total amount of sulfur (S) (Ca+S) ((Na+K) / (Ca+S)), the mass ratio of calcium content (Ca) to sulfur content (S) (Ca / S), the mass ratio of calcium content (Ca) to chlorine content (Cl) (Ca / Cl), the mass ratio of sulfur content (S) to chlorine content (Cl) (S / Cl), the percentage of the total amount of ruthenium content (Ru) and rhodium content (Rh) (Ru+Rh) relative to the total amount of ash, the percentage of palladium content (Pd) relative to the total amount of ash, and the percentage of phosphorus content (P) were calculated and the results are shown in Table 2. Note that Tables 2-1 to 2-4 below are divisions of a single table, and Tables 2-1 to 2-4 together are referred to as Table 2.

[0388] The screw-type twin-screw extruder dryer used consisted of one feed barrel, three dewatering barrels (the first to third dewatering barrels), five drying barrels (the first to fifth drying barrels), and a die section. The operating conditions for the screw-type twin-screw extruder dryer were as follows.

[0389] Set temperature of each barrel: ・1st to 3rd dewatering barrels: 90 to 120°C ・1st to 5th drying barrels: 120 to 180°C Operating conditions: ・Diameter (D) of the screw in the barrel unit: 132 mm ・Total length (L) of the screw in the barrel unit: 4620 mm ・L / D: 35 ・Rotation speed of the screw in the barrel unit: 135 rpm ・Residence time: 100 seconds ・Decompression degree of drying barrel: 10 kPa ・Resin pressure at the die: 2 MPa

[0390] (Baling) After the extruded dried rubber sheet (hydrogenated nitrile rubber sheet) cooled to 50°C or lower, it was cut into pieces each having a predetermined length of 650 mm, and 10 pieces were laminated to obtain hydrogenated nitrile rubber bale A. When the same measurement as that performed for the hydrogenated nitrile rubber A described above was performed on the obtained hydrogenated nitrile rubber bale A, the measured values were the same. Note that the respective properties of the hydrogenated nitrile rubber bale are the same as those of hydrogenated nitrile rubber A, so descriptions thereof in Table 2 are omitted.

[0391] <Manufacture of Lithium Ion Secondary Battery> (Manufacture of Binder for Positive Electrode) 920 parts of NMP were weighed into a container with a stirring blade having an internal volume of 2 L, and heated to 80°C. Next, 80 parts of the hydrogenated nitrile rubber bale A manufactured above, cut into pieces of about 1 cm square, were added, and dissolved while continuing stirring for 5 hours, to prepare binder A for positive electrode having a solid content concentration of 8%. The long-term storage stability of the prepared positive electrode binder was evaluated, and the results are shown in Table 2.

[0392] (Preparation of Conductive Material Dispersion) 0.2 parts of TUBALL SWCNT (manufactured by OCSiAl, single-walled carbon nanotubes) as a conductive material, 25 parts of the positive electrode binder composition having a solid content concentration of 8% obtained according to the above (corresponding to 4 parts as solid content), and 74.8 parts of NMP as an organic solvent were added, and stirred using a disperser (3000 rpm, 10 minutes). Thereafter, a bead mill using zirconia beads with a diameter of 1 mm (manufactured by Ashizawa Finetech, "LMZ015") was used, and mixing was performed at a peripheral speed of 8 m / s for 1 hour to prepare conductive material dispersion A. The dispersibility and stability of the prepared conductive material dispersion were evaluated, and the results thereof are shown in Table 2.

[0393] (Preparation of cathode slurry) In the conductive material dispersion described above, a ternary active material having a layered structure (LiNi) is added as the cathode active material. ０．５ Co ０．２ Mn ０．３ O ２ 98.5 parts of (average particle size: 10 μm), 1.0 part of polyvinylidene fluoride as a binder, 0.5 parts (solid content equivalent) of the conductive material dispersion, and NMP were added and mixed in a planetary mixer (60 rpm, 30 minutes) to prepare a cathode slurry. The amount of NMP added was adjusted so that the viscosity of the resulting cathode slurry (measured using a single-cylinder rotational viscometer in accordance with JIS Z8803:1991; temperature: 25°C, rotation speed: 60 rpm) was in the range of 4000 to 5000 mPa·s.

[0394] (Preparation of the positive electrode) A 20 μm thick aluminum foil was prepared as the current collector. The slurry for the positive electrode was dried onto the aluminum foil using a comma coater, and the basis weight after drying was 20 mg / cm². ２ The material was applied to the surface, dried at 120°C for 5 minutes, then at 130°C for 5 minutes, and finally heat-treated at 60°C for 10 hours to obtain a cathode base. This cathode base was rolled using a roll press to obtain a density of 3.5 g / cm³. ３ A sheet-like positive electrode was fabricated consisting of a positive electrode composite layer and aluminum foil. This sheet-like positive electrode was cut to a width of 4.8 cm and a length of 50 cm to form positive electrode A for a lithium-ion secondary battery. The peel strength, flexibility, and warp characteristics of the obtained positive electrode were measured, and the results are shown in Table 2.

[0395] (Production of Negative Electrode) Into a 5 MPa pressure-resistant container equipped with a stirrer, 33 parts of 1,3-butadiene, 3.5 parts of itaconic acid as a carboxylic acid group-containing monomer, 63.5 parts of styrene as an aromatic vinyl monomer, 0.4 parts of sodium dodecylbenzenesulfonate as an emulsifier, 150 parts of ion-exchanged water, and 0.5 parts of potassium persulfate as a polymerization initiator were added. After sufficient stirring, the mixture was heated to 50°C to initiate polymerization. When the polymerization conversion rate reached 96%, the reaction was cooled and the polymerization reaction was stopped to obtain a mixture containing a particulate binder (styrene-butadiene copolymer). A 5% aqueous sodium hydroxide solution was added to the above mixture to adjust the pH to 8, and then unreacted monomers were removed by heating and vacuum distillation. Thereafter, the mixture was cooled to 30°C or lower to obtain an aqueous dispersion containing a binder for a negative electrode.

[0396] Next, 48.75 parts of artificial graphite and 48.75 parts of natural graphite as negative electrode active materials, and 1 part of carboxymethyl cellulose as a thickener were charged into a planetary mixer. Further, the mixture was diluted with ion-exchanged water so that the solid content concentration became 60%, and then kneaded at a rotation speed of 45 rpm for 60 minutes. Thereafter, 1.5 parts of the aqueous dispersion containing the negative electrode binder obtained as described above, equivalent to solid content, was added, and kneaded at a rotation speed of 40 rpm for 40 minutes. Then, ion-exchanged water was added so that the viscosity became 3000 ± 500 mPa·s (measured with a B-type viscometer at 25°C and 60 rpm), thereby preparing a slurry for a negative electrode mixture layer.

[0397] Next, a copper foil with a thickness of 15 μm was prepared as a current collector. The coating amount of the above negative electrode slurry after drying on both sides of the copper foil was 10 mg / cm ２ The coating was applied so as to obtain the above specification, and dried at 80°C for 5 minutes and 120°C for 5 minutes to obtain a raw negative electrode sheet. This raw negative electrode sheet was rolled by a roll press to have a density of 1.6 g / cm ３ A sheet-shaped negative electrode composed of the negative electrode mixture layer (both sides) and a copper foil was produced. Then, the sheet-shaped negative electrode was cut into a width of 5.0 cm and a length of 52 cm, which was used as a negative electrode for a lithium ion secondary battery.

[0398] (Fabrication of Lithium-ion Secondary Battery) The fabricated positive electrode and negative electrode for the lithium-ion secondary battery were placed with their electrode mixture layers facing each other, and a 15 μm thick separator (microporous polyethylene membrane) was interposed between them. The materials were then wound around a 20 mm diameter core to obtain a wound body. The obtained wound body was then compressed from one direction at a speed of 10 mm / second until its thickness reached 4.5 mm. The compressed wound body was elliptical in plan view, and its ratio of major axis to minor axis (major axis / minor axis) was 7.7.

[0399] Additionally, 1.0 M LiPF is used as the electrolyte. ６ A solution was prepared (solvent: a mixed solvent of ethylene carbonate (EC) / diethyl carbonate (DEC) = 3 / 7 (volume ratio), additive: containing 2% by volume of vinylene carbonate (solvent ratio)).

[0400] Subsequently, the compressed coil was placed in an aluminum laminate case along with 3.2 g of non-aqueous electrolyte. Nickel lead wires were then connected to designated locations on the negative electrode and aluminum lead wires to designated locations on the positive electrode. Finally, the opening of the case was sealed with heat to obtain lithium-ion secondary battery A. This lithium-ion secondary battery was a pouch of a predetermined size capable of housing the above-mentioned coil, and the nominal capacity of the battery was 700 mAh.

[0401] The capacity characteristics, resistance characteristics, cycle characteristics, and high-temperature storage characteristics of the obtained lithium-ion secondary batteries were evaluated, and the results are shown in Table 2.

[0402] (Example 2) Except for changing the polymerization conversion rate to 90%, hydrogenated nitrile rubber B, hydrogenated nitrile rubber bale B, positive electrode binder B, conductive material dispersion B, positive electrode slurry B, positive electrode B, and lithium-ion secondary battery B were obtained in the same manner as in Example 1, and the same evaluation as in Example 1 was performed, and the results are shown in Tables 1 and 2.

[0403] (Example 3) Except for changing the water content of the water-containing crumb after dehydration to 10%, hydrogenated nitrile rubber C, hydrogenated nitrile rubber bale C, positive electrode binder C, conductive material dispersion C, positive electrode slurry C, positive electrode C, and lithium-ion secondary battery C were obtained in the same manner as in Example 1, and the same evaluation as in Example 1 was performed, and the results are shown in Tables 1 and 2.

[0404] (Example 4) Except for changing the water content of the water-containing crumb after dehydration to 25%, hydrogenated nitrile rubber D, hydrogenated nitrile rubber bale D, positive electrode binder D, conductive material dispersion D, positive electrode slurry D, positive electrode D, and lithium-ion secondary battery D were obtained in the same manner as in Example 1, and the same evaluation as in Example 1 was performed, and the results are shown in Tables 1 and 2.

[0405] (Example 5) Except for changing the water content of the water-containing crumb after dehydration to 1%, hydrogenated nitrile rubber E, hydrogenated nitrile rubber bale E, positive electrode binder E, conductive material dispersion E, positive electrode slurry E, positive electrode E, and lithium-ion secondary battery E were obtained in the same manner as in Example 1, and the same evaluation as in Example 1 was performed, and the results are shown in Tables 1 and 2.

[0406] (Example 6) Except for changing the method of adding the polymerization solution in the solidification reaction to being done on the wall side from the middle of the stirring blade of the stirred calcium chloride aqueous solution to the wall of the solidification tank (addition position: 1 / 2 outside), hydrogenated nitrile rubber F, hydrogenated nitrile rubber bale F, positive electrode binder F, conductive material dispersion F, positive electrode slurry F, positive electrode F, and lithium-ion secondary battery F were obtained in the same manner as in Example 3, and the results were shown in Tables 1 and 2.

[0407] (Example 7) Except for changing the polymerization conversion rate to 78%, hydrogenated nitrile rubber G, hydrogenated nitrile rubber bale G, positive electrode binder G, conductive material dispersion G, positive electrode slurry G, positive electrode G, and lithium-ion secondary battery G were obtained in the same manner as in Example 6, and the same evaluation as in Example 6 was performed, and the results are shown in Tables 1 and 2.

[0408] (Example 8) Except for changing the polymerization conversion rate to 82%, hydrogenated nitrile rubber H, hydrogenated nitrile rubber bale H, positive electrode binder H, conductive material dispersion H, positive electrode slurry H, positive electrode H, and lithium-ion secondary battery H were obtained in the same manner as in Example 6, and evaluated in the same manner as in Example 6, and the results are shown in Tables 1 and 2.

[0409] (Example 9) Except for changing the polymerization conversion rate to 93%, hydrogenated nitrile rubber I, hydrogenated nitrile rubber bale I, positive electrode binder I, conductive material dispersion I, positive electrode slurry I, positive electrode I, and lithium-ion secondary battery I were obtained in the same manner as in Example 6, and evaluated in the same manner as in Example 6, and the results are shown in Tables 1 and 2.

[0410] (Example 10) Except for changing the amount of acrylonitrile in emulsion polymerization to 22 parts and the amount of 1,3-butadiene to 78 parts, hydrogenated nitrile rubber J, hydrogenated nitrile rubber bale J, cathode binder J, conductive material dispersion J, cathode slurry J, cathode J, and lithium-ion secondary battery J were obtained in the same manner as in Example 6, and the same evaluation as in Example 6 was performed, and the results are shown in Tables 1 and 2.

[0411] (Example 11) Except for changing the amount of acrylonitrile in emulsion polymerization to 48 parts and the amount of 1,3-butadiene to 52 parts, hydrogenated nitrile rubber K, hydrogenated nitrile rubber veil K, positive electrode binder K, conductive material dispersion K, positive electrode slurry K, positive electrode K, and lithium-ion secondary battery K were obtained in the same manner as in Example 6, and the same evaluation as in Example 6 was performed, and the results are shown in Tables 1 and 2.

[0412] (Example 12) Except for changing the rotation speed of the solidification tank stirring blade to 300 rpm (peripheral speed 1.6 m / s), hydrogenated nitrile rubber L, hydrogenated nitrile rubber bale L, positive electrode binder L, conductive material dispersion L, positive electrode slurry L, positive electrode L, and lithium-ion secondary battery L were obtained in the same manner as in Example 6, and the same evaluation as in Example 6 was performed, and the results are shown in Tables 1 and 2.

[0413] (Reference Example 1) Except for changing the rotation speed of the solidification tank stirring blade to 100 rpm (peripheral speed 0.5 m / s) and changing the water content after dewatering to 25%, hydrogenated nitrile rubber M, hydrogenated nitrile rubber bale M, positive electrode binder M, conductive material dispersion M, positive electrode slurry M, positive electrode M, and lithium-ion secondary battery M were obtained in the same manner as in Example 6, and the same evaluation as in Example 6 was performed, and the results are shown in Tables 1 and 2.

[0414] (Reference Example 2) Except for changing the coagulation reaction to a method of adding an aqueous calcium chloride solution to the polymerization liquid being stirred in the coagulation tank and changing the water content after dehydration to 25%, hydrogenated nitrile rubber N, hydrogenated nitrile rubber bale N, positive electrode binder N, conductive material dispersion N, positive electrode slurry N, positive electrode N, and lithium-ion secondary battery N were obtained in the same manner as in Example 6, and the results were shown in Tables 1 and 2.

[0415] (Reference Example 3) Except for introducing a large amount of steam into the filtrate after the catalyst removal process to produce a water-containing crumb, which was then dried under reduced pressure at 90°C without being subjected to a screw-type twin-screw extruder to produce a crumb-shaped hydrogenated nitrile rubber O, and not producing a hydrogenated nitrile rubber bale, the process was the same as in Reference Example 2 to obtain a positive electrode binder O, a conductive material dispersion O, a positive electrode slurry O, a positive electrode O, and a lithium-ion secondary battery O. The same evaluation as in Reference Example 2 was performed, and the results are shown in Tables 1 and 2.

[0416] (Reference Example 4) 20 kg of the clam-shaped hydrogenated nitrile rubber O obtained in Reference Example 3 was filled into a 300 × 650 × 300 mm bailer and compacted at a pressure of 3 MPa for 30 seconds to obtain a hydrogenated nitrile rubber bale P. Then, the hydrogenated nitrile rubber bale P was dissolved in NMP to produce a positive electrode binder P. Using these, a conductive material dispersion P, a positive electrode slurry P, a positive electrode P, and a lithium-ion secondary battery P were obtained in the same manner as in Reference Example 3, and the same evaluation as in Reference Example 3 was performed, and the results are shown in Tables 1 and 2.

[0417] (Reference Example 5) Nitrile rubber, hydrogenated nitrile rubber, hydrogenated nitrile rubber bale, cathode binder, conductive material dispersion, cathode slurry, cathode, and lithium-ion secondary battery were obtained in the same manner as in Reference Example 4, except that the pH of the emulsion polymerization solution after the addition of an anti-aging agent was adjusted to 3.5 to obtain a polymer pH of 3.5. The same evaluation as in Reference Example 4 was performed. The results were the same as in Reference Example 4, except that the evaluation rank of the resistance characteristics was lowered.

[0418] (Reference Example 6) Nitrile rubber, hydrogenated nitrile rubber, hydrogenated nitrile rubber bale, cathode binder, conductive material dispersion, cathode slurry, cathode, and lithium-ion secondary battery were obtained in the same manner as in Reference Example 4, except that the pH of the emulsion polymerization solution after the addition of an anti-aging agent was adjusted to 9 to obtain a polymer pH of 9 for the nitrile rubber, and the same evaluation as in Reference Example 4 was performed. The results were the same as in Reference Example 4, except that the evaluation rank of the capacity characteristics was lowered.

[0419] (Comparative Example 1) Except for changing the rotation speed of the solidification tank stirring blade to 100 rpm (peripheral speed 0.5 m / s) and not performing dewatering, hydrogenated nitrile rubber Q, positive electrode binder Q, conductive material dispersion Q, positive electrode slurry Q, positive electrode Q, and lithium-ion secondary battery Q were obtained in the same manner as in Reference Example 3, and the results were shown in Tables 1 and 2 after evaluation in the same manner as in Reference Example 3.

[0420] (Comparative Example 2) Hydrogenated nitrile rubber R, cathode binder R, conductive material dispersion R, cathode slurry R, ​​cathode R, and lithium-ion secondary battery R were obtained in the same manner as in Comparative Example 1, except that an antioxidant was not added to the emulsion polymerization solution after emulsion polymerization. The same evaluation as in Comparative Example 1 was performed, and the results are shown in Tables 1 and 2.

[0421] (Comparative Example 2-2) Except for changing the amount of Grubbs catalyst added in the hydrogenation reaction to 1000 ppm, hydrogenated nitrile rubber R-2, positive electrode binder R-2, conductive material dispersion R-2, positive electrode slurry R-2, positive electrode R-2, and lithium-ion secondary battery R-2 were obtained in the same manner as in Comparative Example 1, and the same evaluation as in Comparative Example 1 was performed, and the results are shown in Tables 1 and 2.

[0422]

[0423]

[0424]

[0425]

[0426]

[0427]

[0428]

[0429]

[0430] From Tables 1 and 2, it can be seen that in the emulsion polymerization step, by using an organic polymerization initiator of cumene hydroperoxide and controlling the polymerization temperature and polymerization conversion rate, the proportion of 1,2-bond units in the 1,3-butadiene polymerization units of the produced hydrogenated nitrile rubber can be adjusted to a high level (comparison within Examples 1 to 2 and Examples 6 to 9).

[0431] From Tables 1 and 2, it can be seen that the bulk specific gravity of hydrogenated nitrile rubber is highest when hydrogenated nitrile rubber is recovered after the hydrogenation reaction using a screw-type twin-screw extrusion dryer and extruded into a sheet (which contains less internal air: Examples 1 to 12 and Reference Examples 1 to 2). Next, the bulk specific gravity is high for the bailed crumb-shaped hydrogenated nitrile rubber obtained by directly drying under reduced pressure the water-containing crumbs produced by coagulating the cement (organic solvent reaction solution) after the hydrogenation reaction, and then baling the crumb-shaped hydrogenated nitrile rubber under pressure (Reference Example 4), while the crumb-shaped hydrogenated nitrile rubber before baling has an extremely low bulk specific gravity (Reference Example 3 and Comparative Examples 1 to 2-2).

[0432] From Tables 1 and 2, it can be seen that D50 / D10 or D90 / D10 in the particle size distribution of hydrogenated nitrile rubber can be reduced by performing dehydration and drying using a screw-type twin-screw extrusion dryer in the recovery step of hydrogenated nitrile rubber (Examples 1 to Reference Example 2). It is inferred that this is because the aggregability of hydrogenated nitrile rubber is reduced by melt-kneading in the screw-type twin-screw extrusion dryer.

[0433] Tables 1 and 2 show that the particle size distribution and particle shape of the resulting water-containing crumbs vary greatly depending on the conditions of the solidification reaction after emulsion polymerization of nitrile rubber (number of stirs of the solidification solution and polymerization solution, solidification method depending on whether polymerization solution or solidification solution is added, and the position of addition of the polymerization solution), and that the ash content of the produced hydrogenated nitrile rubber changes significantly. Although this specification does not show the measured values ​​of the ash content and ash component content of the nitrile rubber before hydrogenation, these values ​​were almost the same as those of the final produced hydrogenated nitrile rubber and did not change.

[0434] Tables 1 and 2 show that when the polymerization solution is added to a coagulation solution vigorously stirred at 600 rpm, 99% by mass of the water-containing crumbs are between 1.7 and 8 mm in size, and over 80% by mass are between 3.35 and 4.75 mm in size. This indicates that the ash content in the hydrogenated nitrile rubber produced is reduced, resulting in good workability, as well as good washing and dewatering efficiency (Examples 1-5). Furthermore, in this coagulation reaction, when the polymerization solution is added to the center of the vigorously stirred coagulation solution (where the coagulation solution forms a vortex and the central stirring blade is visible, and the solution is applied directly to the stirring blade), many of the resulting water-containing crumbs have a large hole shape in the center, and the ash content in the hydrogenated nitrile rubber obtained by hydrogenating the nitrile rubber after washing and dewatering can be reduced to about 0.14% (Examples 1-2). On the other hand, when the addition position of the polymerization solution was changed to be closer to the wall between the stirring blade and the tank wall (added directly to the coagulation solution), the particle size distribution of the water-containing crumb did not change much (1.7-8 mm was 94-95% by mass and 2.36-4.75 mm was nearly 70% by mass), but it was found that the water-containing crumb had almost no perforations, and the ash content in the hydrogenated nitrile rubber could only be reduced to about 0.5% (comparison between Examples 1-5 and Examples 6-11).

[0435] Tables 1 and 2 show that when the rotation speed of the stirred solidifying liquid is reduced from 600 rpm to 300 rpm, the proportion of water-containing crumbs of 1.7-8 mm is 87% by mass, but the proportion of water-containing crumbs of 2.36-4.75 mm is less than 50% by mass. Furthermore, when the speed is reduced to 100 rpm, the proportion of water-containing crumbs of 1.7-8 mm is 80% by mass, but the proportion of water-containing crumbs of 2.36-4.75 mm is drastically reduced to 26% by mass (most of which are 4.75 mm or larger, and there are also many water-containing crumbs of 8-9.5 mm), and it can be seen that the ash content in the hydrogenated nitrile rubber produced can only be reduced to about 0.7% by mass and 1% by mass (Example 12 and Reference Example 1).

[0436] Tables 1 and 2 show that when the coagulation method is changed to adding the coagulation solution to the stirred polymerization solution, even with vigorous stirring at 600 rpm, the amount of water-containing crumbs produced is not significantly different from Reference Example 1, with 25% by mass of crumbs measuring 2.36 to 4.75 mm. However, only about 45% by mass of crumbs measuring 1.7 to 8 mm are produced, and the remaining crumbs consist mostly of those larger than 8 mm and those smaller than 1.7 mm, resulting in a higher amount of residual ash in the produced hydrogenated nitrile rubber (Reference Examples 2-4). Furthermore, reducing the rotation speed of the polymerization solution to 100 rpm further increases the amount of residual ash in the hydrogenated nitrile rubber (comparison of Reference Examples 2-4 and Comparative Examples 1-2).

[0437] Tables 1 and 2 show that, in the dehydration process of the water-containing crumb produced by the coagulation reaction, the amount of ash remaining in the nitrile rubber differs significantly depending on the water content after dehydration (comparison of Examples 1 to 5). Furthermore, although only optimal values ​​are shown in these examples, the amount of ash in hydrogenated nitrile rubber is greatly affected by the concentration of the coagulation solution (calcium chloride aqueous solution) used in nitrile rubber production, the washing temperature, and the dehydration temperature. If these values ​​deviate excessively from the optimal values, the amount of ash in the hydrogenated nitrile rubber increases.

[0438] Tables 1 and 2 show that when the ash content of hydrogenated nitrile rubber is reduced to about 0.5%, the sodium and potassium content in the ash is almost eliminated, and most of the components in the ash become calcium and sulfur (comparison between Examples 1-11 and Examples 12-2).

[0439] In reducing the ash content of hydrogenated nitrile rubber, sodium and potassium, which are ash components, are used in many polymerization auxiliary materials, including emulsifiers in nitrile rubber production. These ions become embedded in the water-containing crumb during the coagulation reaction and are difficult to remove by washing alone. However, when the water-containing crumb is produced under the specific coagulation conditions described above, both washing and dewatering efficiency are significantly improved. On the other hand, as the ash content is reduced, only calcium and sulfur components remain in the ash. This is presumed to be because, since only calcium chloride is used as a coagulant, the chlorine in the calcium chloride is exchanged for a sulfur-containing acid during the coagulation reaction. In other words, many compounds such as sulfates and sulfonates are used as polymerization auxiliary materials, but calcium salts suddenly become poorly soluble, and it is thought that they could not be removed from the water-containing crumb by normal washing and dewatering. These can be inferred from the following changes: the ratio of the total amount of sodium (Na) and potassium (K) in the ash (Na+K) decreases, the ratio of the total amount of calcium (Ca) and sulfur (S) in the ash (Ca+S) increases, the mass ratio of the total amount of sodium (Na) and potassium (K) in the ash (Na+K) to the total amount of calcium (Ca) and sulfur (S) in the ash (Ca+S) ((Na+K) / (Ca+S)) suddenly decreases; or the mass ratio of sulfur (S) to chlorine (Cl) in the ash (S / Cl) and the mass ratio of calcium (Ca) to chlorine (Cl) in the ash (Ca / Cl) suddenly begin to increase (Ca / Cl for calcium chloride is 0.565); and the mass ratio of sulfur (S) to chlorine (Cl) in the ash (S / Cl) suddenly begin to increase.

[0440] One possible cause of sulfur content in ash is sulfur compounds such as t-dodecyl mercaptan, which are molecular weight regulators in polymerization auxiliary materials. However, molecular weight regulators remain at the polymer ends after polymerization in the form of S-alkyl groups, but in ash treatment, SO ２ It is unlikely that these would be excreted. Therefore, it is highly probable that the ash, which is rich in calcium and sulfur, remains as a salt of calcium and sulfur-containing acids. Sulfates and sulfonates are often used as polymerization auxiliary materials, and although these are readily soluble in water during the polymerization reaction, it is suspected that some of them were converted into calcium salts during the coagulation reaction when calcium chloride was used as a coagulant, becoming sparingly soluble and remaining in the nitrile rubber. This salt exchange can be seen from the fact that the mass ratio of calcium to chlorine in the ash (Ca / Cl: calcium chloride = 0.565) increases from 1.5 or higher, to 2 or higher, to 3 or higher, to 5 or higher, and in exchange, the mass ratio of sulfur to chlorine (S / Cl) also increases from 1.5 or higher, to 2 or higher, to 3 or higher, to 5 or higher, and in exchange, to 5 or higher.

[0441] Regarding the ion exchange compound treatment after the hydrogenation reaction, this is carried out by adding aminopropyl-modified silica, an ion exchange compound, to the monochlorobenzene (MCB) solution after the hydrogenation reaction. However, as mentioned above, the ash content and ash component content of the nitrile rubber before hydrogenation and the hydrogenated nitrile rubber produced remained almost unchanged. From this, it was found that these ion exchange compound treatments hardly removed the ash in the hydrogenated nitrile rubber, and instead reduced the ruthenium (Ru) content, which is the hydrogenation catalyst. This is because while the hydrogenation catalyst dissolved in the cement (MCB solution) can be removed, the ash in the precursor nitrile rubber, which does not dissolve, can hardly be removed. Therefore, to reduce the ash content of hydrogenated nitrile rubber, it was necessary to reduce the ash content in the precursor nitrile rubber.

[0442] The properties of the hydrogenated nitrile rubber, such as the repeating unit ratio, polymer pH, antioxidant content, ash content, the ratio of the total amount of sodium (Na) and potassium (K) in the ash (Na+K), the ratio of the total amount of calcium (Ca) and sulfur (S) in the ash (Ca+S), the mass ratio of the total amount of sodium (Na) and potassium (K) in the ash (Na+K) to the total amount of calcium (Ca) and sulfur (S) in the ash (Ca+S) ((Na+K) / (Ca+S)), the ratio of calcium (Ca) and sulfur (S) in the ash (Ca / S), the mass ratio of calcium (Ca) and chlorine (Cl) in the ash (Ca / Cl), and the mass ratio of sulfur (S) and chlorine (Cl) in the ash (S / Cl), were almost inherited and equivalent to those of the nitrile rubber before hydrogenation, although these are not shown in this embodiment.

[0443] Table 2 shows that the polymer contains acrylonitrile polymerization units and 1,3-butadiene polymerization units, has a weight-average molecular weight (Mw) in the range of 10,000 to 5,000,000, a ratio of Z-average molecular weight (Mz) to weight-average molecular weight (Mw) (Mz / Mw) of 1.5 or more, an iodine value of 100 mg / 100 mg or less, and a bulk density of 0.7 g / cm³. ３ In summary, the hydrogenated nitrile rubbers A to L of the present invention, which have an ash content of 0.7% by mass or less and a total amount of calcium content (Ca) and sulfur content (S) in the ash (Ca + S) of 40% by mass or more, exhibit excellent dispersibility and stability of conductive material dispersions, superior capacitance characteristics, resistance characteristics, cycle characteristics, and high-temperature storage characteristics of electrochemical elements, and also enhance the long-term storage properties of positive electrode binders, as well as the peel strength, flexibility, and warp characteristics of electrodes.

[0444] Table 2 shows that the product contains acrylonitrile polymerization units and 1,3-butadiene polymerization units, has an iodine value of 100 mg / 100 mg or less, a weight-average molecular weight (Mw) in the range of 10,000 to 2,500,000, and a bulk density of 0.7 g / cm³. ３In summary, the hydrogenated nitrile rubbers A to L of the present invention, which have an ash content of 0.7% by mass or less and a total amount of calcium (Ca) and sulfur (S) content in the ash (Ca + S) of 40% by mass or more, exhibit excellent dispersibility and stability of conductive material dispersions, superior cycle characteristics and high-temperature storage characteristics of electrochemical elements, and also enhance the long-term storage properties of positive electrode binders, as well as the peel strength, flexibility, and warp characteristics of electrodes.

[0445] Table 2 shows that the product contains acrylonitrile polymerization units and 1,3-butadiene polymerization units, has an iodine value of 100 mg / 100 mg or less, a weight-average molecular weight (Mw) in the range of 10,000 to 2,500,000, and a bulk density of 0.7 g / cm³. ３ As described above, the hydrogenated nitrile rubbers A to L of the present invention, which have an ash content of 0.7% by mass or less and a mass ratio ((Na+K) / (Ca+S)) of the total amount of sodium (Na) and potassium (K) content in the ash (Na+K) to the total amount of calcium (Ca) and sulfur (S) content (Ca+S) of the ash ((Na+K) / (Ca+S)) of 0.5 or less, exhibit excellent dispersibility and stability of conductive material dispersions, excellent cycle characteristics and high-temperature storage characteristics of electrochemical elements, and also improve the long-term storage properties of positive electrode binders, as well as the peel strength, flexibility, and warp characteristics of electrodes.

[0446] Table 2 shows that the product contains acrylonitrile polymerization units and 1,3-butadiene polymerization units, has an iodine value of 100 mg / 100 mg or less, a weight-average molecular weight (Mw) in the range of 10,000 to 2,500,000, and a bulk density of 0.7 g / cm³. ３ As described above, the hydrogenated nitrile rubbers A to L of the present invention, which have an ash content of 0.7% by mass or less, a mass ratio of calcium content (Ca) to chlorine content (Cl) in the ash (Ca / Cl) of 1 or more, and a mass ratio of sulfur content (S) to chlorine content (Cl) (S / Cl) of 1 or more, exhibit excellent dispersibility and stability of conductive material dispersions, excellent cycle characteristics and high-temperature storage characteristics of electrochemical elements, and also improve the long-term storage properties of positive electrode binders, as well as the peel strength, flexibility, and warp characteristics of electrodes.

[0447] Table 2 shows that it contains acrylonitrile polymerization units and 1,3-butadiene polymerization units, has an iodine value of 100 mg / 100 mg or less, contains an antioxidant, and has a bulk density of 0.7 g / cm³. ３ As described above, the hydrogenated nitrile rubbers A to L of the present invention, which have an ash content of 0.7% by mass or less and a total amount of calcium content (Ca) and sulfur content (S) in the ash (Ca + S) of 40% by mass or more, exhibit excellent stability of conductive material dispersions, excellent peel strength of electrodes, and excellent capacitance characteristics, cycle characteristics, and high-temperature storage characteristics of electrochemical elements. Furthermore, they also enhance the long-term storage properties of positive electrode binders, the dispersibility of conductive material dispersions, the flexibility and warping characteristics of electrodes, and the resistance characteristics of electrochemical elements.

[0448] Regarding the stability of the conductive material dispersion, all of the hydrogenated nitrile rubbers A to L of the present invention exhibit good stability, but it can be seen that stability deteriorates when the bulk density decreases and the amount of internal air increases (Reference Examples 3-4 and Comparative Example 1). Furthermore, the stability of the conductive material dispersion decreases not only with regard to bulk density, but also when hydrogenated nitrile rubber that does not contain antioxidants such as phenolic antioxidants is used (Comparative Example 2), and also when the iodine value of the hydrogenated nitrile rubber significantly exceeds 100 mg / 100 mg (Comparative Example 2-2).

[0449] Regarding the peel strength of the electrodes, hydrogenated nitrile rubbers A to L of the present invention all show good results. On the other hand, it can be seen that the peel strength of the electrodes decreases significantly when the hydrogenated nitrile rubber does not contain an anti-aging agent (Comparative Example 2). Furthermore, the peel strength of the electrodes tends to decrease when the ash content of the specific ash component described later is excessively reduced, indicating that the ash content of the specific component of the hydrogenated nitrile rubber improves the peel strength of the electrodes (Example 5). In addition, although not shown in this example, the peel strength of the electrodes decreases when the Mw or Mz / Mw of the hydrogenated nitrile rubber is excessively small.

[0450] Regarding capacity characteristics, it can be seen that the ash content and ash components of the hydrogenated nitrile rubber have a significant impact. In particular, it can be seen that the performance can be almost completely improved by reducing the ash content of the hydrogenated nitrile rubber to about 0.5% by mass. This is because when the ash content is reduced to about 0.5% by mass, the sodium and potassium content in the ash almost disappears, and it is presumed that the deterioration of capacity characteristics is caused by the sodium and potassium in the ash destroying the negative electrode active material. Regarding capacity characteristics, it can also be seen that the performance improves when the proportion of 1,2-bonding units in the 1,3-butadiene polymerization units is increased (comparison in Examples 1-2 and Examples 6-9). Furthermore, as shown in Reference Example 6, the performance deteriorates when hydrogenated nitrile rubber, which is obtained by hydrogenating nitrile rubber with a high polymer pH of 9, is used.

[0451] Regarding cycle characteristics, hydrogenated nitrile rubbers A to L of the present invention all show good results, but it can be seen that they tend to decrease as the number of acrylonitrile polymerization units increases (Example 11). Also, cycle characteristics decrease when the iodine value of the hydrogenated nitrile rubber significantly exceeds 100 mg / 100 mg (Comparative Example 2-2).

[0452] Regarding high-temperature storage characteristics, it can be seen that the ash content of hydrogenated nitrile rubber has a significant impact. However, unlike the relationship between the volume characteristics and the sodium and potassium content in the ash, it can be seen that even when the ash content is 0.5% by mass or less, the lower the ash content, the better the high-temperature storage characteristics become. When the ash content is 0.5% by mass or less, the ash components consist of calcium and sulfur, and their impact on high-temperature storage characteristics is smaller than that of sodium and potassium. Furthermore, as the ash content, which is high in calcium and sulfur, is reduced, the peel strength of the electrode tends to decrease (Example 5), indicating that this ash content works well for electrode peel strength.

[0453] Furthermore, regarding the long-term storage properties of the positive electrode binder, the hydrogenated nitrile rubbers A to L of the present invention are found to be good (Examples 1 to 12 and Reference Examples 1 to 2). On the other hand, the properties deteriorate when the D50 / D10 or D90 / D10 in the particle size distribution of the hydrogenated nitrile rubber increases (Reference Examples 3 to Comparative Examples 2-2).

[0454] Regarding the dispersibility of the conductive material dispersion, it can be seen that hydrogenated nitrile rubbers A to L of the present invention exhibit good dispersibility. On the other hand, when the proportion of acrylonitrile polymerization units in the hydrogenated nitrile rubber decreases, there is a tendency for the dispersibility of the conductive material dispersion to decrease (Example 10). In addition, although not shown in this example, when the Mw or Mz / Mw of the hydrogenated nitrile rubber becomes excessively large, the dispersibility of the conductive material dispersion decreases.

[0455] Regarding the flexibility and warpage characteristics of the electrodes, it can be seen that by adjusting the ratio of 1,2-bonding units in the 1,3-butadiene polymerization units of the hydrogenated nitrile rubber, both properties can be greatly enhanced and a high degree of balance can be achieved (Examples 6-9). Therefore, it can be seen that in order to greatly enhance and balance the flexibility and warpage characteristics of the electrodes, and the capacitance characteristics of the electrochemical element, it is necessary to adjust the ratio of 1,2-bonding units in the 1,3-butadiene polymerization units of the hydrogenated nitrile rubber.

[0456] Regarding resistance characteristics, the hydrogenated nitrile rubbers A to L of the present invention show good results. On the other hand, when the proportion of acrylonitrile polymerization units in the hydrogenated nitrile rubber decreases, the dispersibility of the conductive material dispersion and the resistance characteristics of the electrochemical element tend to decrease (Example 10). Although not shown in this example, if the Mw or Mz / Mw of the hydrogenated nitrile rubber becomes excessively large, the dispersibility of the conductive material dispersion and the resistance characteristics of the electrochemical element decrease. Furthermore, as described in Reference Example 5, the resistance characteristics decrease when the polymer pH of the hydrogenated nitrile rubber becomes excessively low.

[0457] As shown in Table 2 above, the hydrogenated nitrile rubbers A to L of the present invention enhance the long-term storage properties of the positive electrode binder, the dispersibility and stability of the conductive material dispersion, the peel strength, flexibility and warping characteristics of the electrode, and the capacitance, resistance, cycle characteristics and high-temperature storage characteristics of the electrochemical element, and it can be seen that these properties are highly balanced.

[0458] 10 Emulsion polymerization apparatus 11 Polymerization tank 12, 32, 52, 122, 132, 152a, 152b Agitator 13, 33, 53, 123, 133, 153a, 153b Agitator blade 14, 34, 54, 124, 134, 154a, 154b Motor 30, 150 Solidification apparatus 31 Solidification tank 38, 58, 158 Drainer 50 Washing apparatus 51 Washing tank 55, 71c, 125, 135, 155a Heating apparatus 56 Heating section 70 Squeezer 70a Clam supply section 70b Clam discharge section 71 Heating mechanism 71a, 72a Chamber 71b, 72b Roller 72 Pressurizing mechanism 73 Connecting section 75, 110 Crushing device 111 Conveyor 120 Dissolving device 121 Dissolving tanks 126, 136 Heating equipment 130 Hydrogenation reactor 131 Reaction tank 137 Hydrogen supply source 138 Catalyst supply source 151a First solidification tank 151b Second solidification tank 156a Heating section 157a, 157b Pump 160 Screw-type twin-screw extruder dryer 161 Supply barrel section 162 Dewatering barrel section 163 Drying barrel section 164 Die section 165 Screw drive section 170 Cooling device 171 Shower device 172, 185 Roller conveyor 173 Conveyor-type cooling device 174 Conveyor conveyor 175 Cooling means 176 Air cooling tank 177 Air blowing duct 180 Cutting device 181 Clamper 182 Cutter 183 Workbench 190 Packaging device

Claims

1. Hydrogenated nitrile rubber containing acrylonitrile polymerization units and 1,3-butadiene polymerization units, having an iodine value of 100 mg / 100 mg or less and an ash content of 0.7% by mass or less.

2. The weight-average molecular weight (Mw) is in the range of 10,000 to 5,000,000, the ratio of Z-average molecular weight (Mz) to weight-average molecular weight (Mw) (Mz / Mw) is 1.5 or higher, and the bulk density is 0.7 g / cm³. ３ The hydrogenated nitrile rubber according to claim 1, wherein the total amount (Ca + S) of calcium content (Ca) and sulfur content (S) in the ash is 40% by mass or more.

3. The weight-average molecular weight (Mw) is in the range of 10,000 to 2,500,000, and the bulk density is 0.7 g / cm³. ３ The hydrogenated nitrile rubber according to claim 1, wherein the total amount (Ca + S) of calcium content (Ca) and sulfur content (S) in the ash is 40% by mass or more.

4. The weight-average molecular weight (Mw) is in the range of 10,000 to 2,500,000, and the bulk density is 0.7 g / cm³. ３ The hydrogenated nitrile rubber according to claim 1, wherein the mass ratio ((Na+K) / (Ca+S)) of the total amount of sodium content (Na) and potassium content (K) in the ash (Na+K) to the total amount of calcium content (Ca) and sulfur content (S) (Ca+S) is 0.5 or less.

5. The weight-average molecular weight (Mw) is in the range of 10,000 to 2,500,000, and the bulk density is 0.7 g / cm³. ３ The hydrogenated nitrile rubber according to claim 1, wherein the mass ratio (Ca / Cl) of calcium content (Ca) to chlorine content (Cl) in the ash is 1 or more, and the mass ratio (S / Cl) of sulfur content (S) to chlorine content (Cl) is 1 or more.

6. Contains an anti-aging agent and has a bulk density of 0.7 g / cm³. ３ The hydrogenated nitrile rubber according to claim 1, wherein the total amount (Ca + S) of calcium content (Ca) and sulfur content (S) in the ash is 40% by mass or more.

7. A method for producing hydrogenated nitrile rubber according to claim 6, comprising: an emulsion polymerization step of emulsion polymerization of monomer components containing acrylonitrile and 1,3-butadiene to obtain an emulsion polymerization liquid; an antioxidant addition step of adding an antioxidant to the obtained emulsion polymerization liquid; a coagulation step of adding the emulsion polymerization liquid to which the antioxidant has been added to a coagulation liquid that is being vigorously stirred to produce a water-containing crumb; a washing step of washing the produced water-containing crumb; a dehydration step of dehydrating the washed water-containing crumb to a water content of 35% by mass or less; a drying step of drying the polymer after dehydration; a hydrogenation step of dissolving the dried polymer in an organic solvent and carrying out a hydrogenation reaction; and a hydrogenated polymer dehydration and drying step of coagulating the reaction liquid after the hydrogenation reaction and dehydrating and drying the produced water-containing crumb using a screw-type twin-screw extruder to extrude dried rubber.

8. A hydrogenated nitrile rubber bale obtained by bailing the hydrogenated nitrile rubber described in claim 6.

9. An electrode material comprising the hydrogenated nitrile rubber described in claim 6.

10. An electrode binder obtained by dissolving the hydrogenated nitrile rubber described in claim 6 in N-methylpyrrolidone (NMP).

11. A conductive material dispersion obtained by dissolving or dispersing the hydrogenated nitrile rubber and conductive material described in claim 6 in N-methylpyrrolidone (NMP).

12. An electrode slurry obtained by dissolving or dispersing an electrode active material, a conductive material, and the hydrogenated nitrile rubber described in claim 6 in N-methylpyrrolidone (NMP).

13. An electrode comprising the hydrogenated nitrile rubber described in claim 6.

14. An electrochemical element comprising the hydrogenated nitrile rubber described in claim 6.

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