Method for producing conductive pigment paste and method for producing composite paste

Abstract

The present invention addresses the problem of providing a conductive pigment slurry and a composite slurry having excellent pigment dispersibility and storage stability even at a high pigment concentration, and further providing an electrode layer for a lithium ion secondary battery having excellent numerous properties (conductivity, battery performance, and the like). As a solution, provided is a method for producing a conductive pigment slurry containing a pigment dispersion resin (A), a conductive pigment (B), a solvent (C), and optionally a fluororesin (D), the method being characterized by including a step in which the following steps are performed in this order: a step for producing a conductive pigment slurry containing a pigment dispersion resin (A), a conductive pigment (B), a solvent (C), and optionally a fluororesin (D); step 1: a step for pulverizing a conductive pigment composition in which the pigment concentration of a conductive pigment (B) is 50 mass% or more with a pulverizer, and Step 2: a step for mixing and dispersing components containing a pigment dispersion resin (A), a solvent (C), and optionally a fluororesin (D) into the conductive pigment composition obtained in Step 1.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a conductive pigment slurry with excellent conductivity, pigment dispersibility and storage stability even at high pigment concentrations, a method for manufacturing a composite slurry, and a method for manufacturing a battery electrode layer with excellent battery performance. Background Technology

[0002] Traditionally, slurry-like pigment dispersions, obtained by dispersing pigments in a mixture of pigment dispersion resin and solvent, have been widely used in coatings, battery electrodes, coating materials, electromagnetic shielding, display panels, touch screen panels, colored films, colored flakes, cosmetic materials, protective materials, magnet-modified materials, printing inks, device components, electronic machine components, printed wiring boards, solar cells, functional rubber components, and resin molding films. Furthermore, to impart electrostatic coating properties, conductivity, electromagnetic shielding properties, and antistatic properties to these materials, they are often incorporating conductive pigments or conductive polymers.

[0003] In these fields, there is an increasing demand for improved pigment properties such as dispersibility, storage stability, conductivity, coatability, and finished product properties. Therefore, pigment dispersion resins and pigment slurries with excellent pigment dispersion capabilities and excellent pigment dispersion stability that prevents pigment particles from re-aggregating in the formed pigment dispersion are being developed.

[0004] In the design of pigment slurries, it is particularly important to produce high-concentration and uniformly dispersed pigment slurries with a small amount of pigment dispersion resin in order to prevent the pigment dispersion resin from adversely affecting the conductivity of the final product such as the coating film, or from the perspective of reducing the amount of solvent and pigment dispersion resin used or reducing the energy used during drying.

[0005] For example, Patent Document 1 discloses a method for manufacturing an electrode for a non-aqueous electrolyte battery, characterized by comprising the following steps: mixing a carbon-based conductive agent with a dispersing solvent and then dispersing the carbon-based conductive agent using a medium-type disperser; adding an active material and a binder to the slurry obtained in the above steps and mixing them to form an active material slurry; and coating the active material slurry onto an electrode substrate.

[0006] However, these inventions cannot achieve uniform dispersion in slurries with high pigment concentrations and / or high viscosity, resulting in poor storage stability.

[0007] Patent documents Patent Document 1: Japanese Patent Application Publication No. 10-144302 Summary of the Invention The purpose of this invention is to provide a method for manufacturing a conductive pigment slurry with excellent pigment dispersibility and storage stability even in slurries with high pigment concentration and / or high viscosity, and a method for manufacturing a composite slurry, and further to provide a method for manufacturing a coating film (electrode layer for batteries) with excellent finished product properties and conductivity.

[0008] In order to solve the above-mentioned problems, the inventors conducted in-depth research and found that the above-mentioned problems could be solved by a method for manufacturing a conductive pigment slurry, thus completing the present invention. The invention is a method for manufacturing a conductive pigment slurry containing a pigment dispersion resin (A), a conductive pigment (B), a solvent (C), and a fluoropolymer resin (D) which may be included as needed. Its characteristic is that it includes a step of sequentially performing the following steps: Step 1: A step of pulverizing a conductive pigment composition with a pigment concentration of 50% by mass or more of conductive pigment (B) using a pulverizer, and... Step 2: A step of mixing and dispersing the conductive pigment composition obtained in Step 1 with components containing pigment dispersion resin (A), solvent (C), and fluororesin (D) which may be included as needed.

[0009] That is, the present invention provides a method for manufacturing conductive pigment slurry, a method for manufacturing composite slurry, and a method for manufacturing electrode layer for battery.

[0010] Item 1. A method for manufacturing a conductive pigment slurry, comprising a pigment dispersion resin (A), a conductive pigment (B), a solvent (C), and a fluoropolymer resin (D) optionally included, characterized by comprising the following steps performed sequentially. Step 1: A step of pulverizing a conductive pigment composition with a pigment concentration of 50% by mass or more of conductive pigment (B) using a pulverizer, and... Step 2: A step of mixing and dispersing the conductive pigment composition obtained in Step 1 with components containing pigment dispersion resin (A), solvent (C), and fluororesin (D) which may be included as needed.

[0011] Item 2. The method for manufacturing conductive pigment paste according to claim 1 is characterized in that the conductive pigment (B) contains carbon nanotubes (B1).

[0012] Item 3. The method for manufacturing conductive pigment paste according to item 2 is characterized in that, with regard to the carbon nanotubes (B1) before and after pulverization in step 1, the following (1) and (2) are satisfied. (1) With 1560cm -1 Above 1600cm -1The maximum peak intensity is G within the following range, at 1310 cm⁻¹. -1 Above 1350cm -1 The G / D ratio of carbon nanotubes (B1) before pulverization is between 0.1 and 5.0 when the maximum peak intensity D is within the following range. (2) When the G / D ratio of the carbon nanotubes (B1) before pulverization is α and the G / D ratio of the carbon nanotubes (B1) after pulverization is β, β / α < 1.00.

[0013] Item 4. The method for manufacturing conductive pigment paste according to any one of claims 1 to 3 is characterized in that the pigment dispersion resin (A) has at least one alkyl group having 12 or more carbon atoms.

[0014] Item 5. The method for manufacturing conductive pigment paste according to any one of claims 1 to 4 is characterized in that the pigment dispersion resin (A) has at least one polar functional group selected from amide group, imide group, hydroxyl group, carboxyl group, sulfonic acid group, phosphoric acid group, silanol group, cyano group, pyrrolidone group and amino group, and the concentration of polar functional group of pigment dispersion resin (A) is 0.3 mmol / g to 23 mmol / g.

[0015] Item 6. The method for manufacturing a conductive pigment paste according to any one of claims 1 to 5 is characterized in that the conductive pigment paste contains a fluoropolymer (D), and the step of mixing the fluoropolymer (D) includes a step of mixing and dissolving it with a solvent preheated to a liquid temperature of 40°C or higher, or a step of mixing the fluoropolymer (D) with a solvent and then heating it to a temperature of 40°C or higher.

[0016] Item 7. The method for manufacturing conductive pigment paste according to any one of claims 1 to 6 is characterized in that the solvent (C) is N-methyl-2-pyrrolidone.

[0017] Item 8. The manufacturing method according to any one of items 1 to 7 is characterized in that step 2 includes the steps of sequentially performing the following steps, Step 2-1: Based on 100% by mass of the total amount of conductive pigment composition in the dispersed conductive pigment slurry, a component containing 70% by mass or less of the conductive pigment composition is added to a disperser for dispersion treatment; and... Step 2-2: The process of adding the conductive pigment composition into a disperser until the desired concentration is reached for dispersion treatment.

[0018] Item 9. A method for manufacturing a composite slurry for lithium-ion secondary batteries, characterized in that, for the conductive pigment slurry obtained by the method for manufacturing conductive pigment slurry according to any one of claims 1 to 8, the method further includes the following steps: Step 3: The process of mixing at least one electrode active material (F).

[0019] Item 10. A method for manufacturing an electrode layer for a lithium-ion secondary battery, characterized in that it includes a step of coating a composite slurry for a lithium-ion secondary battery obtained by the manufacturing method of item 9 onto a current collector.

[0020] Item 11. A method for manufacturing an electrode for a lithium-ion secondary battery, characterized in that it includes a step of coating an electrode insulating portion on the end or upper layer of the electrode layer obtained by the method for manufacturing an electrode layer for a lithium-ion secondary battery according to item 10.

[0021] The conductive pigment slurry manufacturing method and composite slurry manufacturing method of the present invention exhibit excellent pigment dispersibility and storage stability even in slurries with high pigment concentration and / or high viscosity, and the viscosity of the slurry can be sufficiently reduced by using a smaller amount of dispersing resin. Furthermore, the coated film (electrode layer for batteries) demonstrates excellent product quality, conductivity, and battery performance. Detailed Implementation

[0022] The following provides a detailed description of the methods used to implement this invention.

[0023] Furthermore, it should be understood that the present invention is not limited to the following embodiments, but also includes various modifications implemented without changing the spirit of the present invention.

[0024] Furthermore, in this invention, a composition obtained by pulverizing a conductive pigment (B) with a pigment concentration of 50% or more by mass using a pulverizer is referred to as a "conductive pigment composition".

[0025] A slurry prepared by further incorporating at least one pigment dispersion resin (A), a solvent (C), a fluoropolymer resin (D) which may be included as needed, and other optional components into the conductive pigment composition is called a "conductive pigment slurry".

[0026] The term "conductive pigment paste" refers to a paste containing conductive pigments, not that the paste itself is conductive.

[0027] Alternatively, the conductive pigment slurry can be described as a slurry that does not actually contain electrode active substances.

[0028] A slurry prepared by further formulating at least one electrode active material and optional other components for coating the conductive pigment slurry is called a "composite slurry". The product formed after coating the composite slurry onto the substrate and drying it is called a "coated film" or "composite material layer".

[0029] When the coating film is used for battery electrodes, it can also be called an "electrode layer".

[0030] Carbon nanotubes can be abbreviated as "CNT".

[0031] [Manufacturing method of conductive pigment paste] This invention relates to a method for manufacturing a conductive pigment slurry with a well-dispersed conductive pigment (B). The method comprises a method for manufacturing a conductive pigment slurry containing a pigment dispersion resin (A), a conductive pigment (B), a solvent (C), and a fluoropolymer resin (D) which may be included as needed. The method is characterized by a step (step 1: pulverization step) in which the conductive pigment (B) is first pulverized using a pulverizer to obtain a conductive pigment composition at a pigment concentration of 50% by mass or more (pulverization step), and a step (step 2: dispersion step) in which the conductive pigment composition obtained in step 1 is mixed with and dispersed the components containing the pigment dispersion resin (A), the solvent (C), and the fluoropolymer resin (D) which may be included as needed (dispersion step).

[0032] In addition, the present invention may include other processes between or before and after process 1 and process 2.

[0033] Process 1 (Grinding Process) Step 1 is a step of pulverizing (including depolymerizing) the conductive pigment (B) using a pulverizer to obtain a conductive pigment composition. The pigment concentration of the conductive pigment (B) is typically 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, particularly preferably 99% by mass or more, and even more preferably 100% by mass, based on 100% by mass of the conductive pigment composition. Furthermore, the aforementioned "pigment concentration of the conductive pigment (B)" refers to the pigment concentration of the conductive pigment (B) contained in the conductive pigment composition, excluding pigments or solids other than the conductive pigment (B).

[0034] Other than the conductive pigment (B) in the conductive pigment composition, the solvent, resin and pigment other than the conductive pigment (B) described later may preferably be used.

[0035] Furthermore, the solid content concentration of the conductive pigment composition, based on 100% by mass of the conductive pigment composition, is typically 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, particularly preferably 99% by mass or more, and even more particularly preferably 100% by mass. Additionally, the aforementioned "solid content concentration" refers to the percentage (by mass) of solid content when 1 g of sample is heated and dried at 130°C for 3 hours.

[0036] Furthermore, the conductive pigment composition obtained in step 1 may contain other components besides the conductive pigment (B) as long as the pigment concentration and solid component concentration are as described above. For example, it may contain pigment dispersion resin (A) described later, pigments other than conductive pigment (B), solvent (C), and fluoropolymer (D) as needed. However, it is preferable that the conductive pigment composition contains only conductive pigment (B), and it is particularly preferable that it contains only carbon nanotubes (B1).

[0037] Furthermore, when the conductive pigment paste is used as an electrode layer, it is preferable that it is substantially free of the electrode active material described later, since it is mixed in a subsequent process (process 3).

[0038] Conductive pigments (B) As the conductive pigment (B), a known conductive pigment can be used, preferably containing carbon nanotubes (B1). The conductive pigment (B) may further contain other conductive pigments (B2) besides carbon nanotubes (B1).

[0039] The content of carbon nanotubes (B1) in the conductive pigment (B) is based on 100% by mass of conductive pigment (B), for example, 50% by mass or more, preferably 75% by mass or more, more preferably 95% by mass or more, particularly preferably 99% by mass or more, and even more preferably 100% by mass.

[0040] Carbon nanotubes (B1) As carbon nanotubes (B1), single-layer carbon nanotubes or multi-layer carbon nanotubes can be used alone or in combination. In particular, considering the relationship between viscosity, conductivity and cost, multi-layer carbon nanotubes are preferred.

[0041] When using carbon nanotubes (B1), the content is based on 100% by mass of the total amount of conductive pigment paste, for example, 0.5% by mass or more, preferably 1% by mass or more, more preferably 2% by mass or more, for example, 10% by mass or less, preferably 7% by mass or less, more preferably 6% by mass or less.

[0042] Furthermore, based on a total solid content of 100% by mass of the conductive pigment paste, it is, for example, 5% by mass or more, preferably 10% by mass or more, more preferably 20% by mass or more, for example, 90% by mass or less, preferably 70% by mass or less, more preferably 50% by mass or less.

[0043] The average outer diameter of the carbon nanotube (B1) is, for example, 1 nm or more, preferably 3 nm or more, more preferably 5 nm or more, for example, 30 nm or less, preferably 28 nm or less, more preferably 25 nm or less.

[0044] The average length of the carbon nanotubes (B1) is, for example, 0.1 μm or more, preferably 1 μm or more, more preferably 5 μm or more, for example, 100 μm or less, preferably 80 μm or less, more preferably 60 μm or less.

[0045] The BET specific surface area of ​​carbon nanotubes (B1), considering the relationship between viscosity and conductivity, is typically 100 m². 2 / g or more, preferably 130m 2 / g or more, preferably 160m 2 / g or above, typically 800m 2 / g or less, preferably 600m 2 / g or less, more preferably 400m 2 / g or less.

[0046] The BET specific surface area of ​​the present invention can be calculated using the BET method based on nitrogen adsorption measurement. Specifically, for example, the BET specific surface area (m²) can be measured using a specific surface area measuring device (BERSORP-MAX (Microtrac BEL Co., Ltd.)) according to Japanese Industrial Standard JIS Z8830:2013. 2 / g).

[0047] From the viewpoint of dispersibility and storage properties, the amount of acidic groups in the aforementioned carbon nanotubes (B1) is typically 0.01 mmol / g or more, preferably 0.01 mmol / g or more, typically 1.0 mmol / g or less, preferably 0.5 mmol / g or less, more preferably 0.2 mmol / g or less, and even more preferably 0.1 mmol / g or less. When the amount of acidic groups is 0.01 mmol / g or more, dispersibility is good; furthermore, when it is 1.0 mmol / g or less, storage properties are good.

[0048] The aforementioned acidic groups can be imparted by acid treatment of the carbon nanotubes.

[0049] (Acid treatment method) As for the acid treatment method, there is no particular limitation as long as it allows the carbon nanotubes to come into contact with the acid. Immersion of the carbon nanotubes in an acid treatment solution (an aqueous solution of acid) is preferred. The acid contained in the acid treatment solution is not particularly limited; examples include nitric acid, sulfuric acid, and hydrochloric acid. These can be used alone or in combination of two or more. Nitric acid and sulfuric acid are preferred among these.

[0050] The amount of acidic groups in carbon nanotubes can be adjusted by the concentration, temperature, and treatment time of the acid treatment solution.

[0051] Acid-treated carbon nanotubes can be obtained by removing the remaining acid components adhering to the surface through the cleaning method described later after acid treatment.

[0052] There are no particular limitations on the method for cleaning acid-treated carbon nanotubes, but water washing is preferred. For example, carbon nanotubes can be recovered from acid-treated carbon nanotubes by known methods such as filtration, followed by water washing. After the above cleaning, the acid-treated carbon nanotubes can be obtained by drying to remove water and other substances adhering to the surface, as needed.

[0053] Furthermore, the median particle size (D50), used as a volume conversion of carbon nanotubes (B1), is typically 10 μm or more, preferably 15 μm or more, more preferably 20 μm or more, and typically 250 μm or less, preferably 200 μm or less, more preferably 150 μm or less, when measured using the method described in the following embodiments. Here, the median particle size (D50) can be obtained by irradiating the carbon nanotube particles with a laser and converting the diameter of the carbon nanotubes to spherical shape based on the scattered light. A larger median particle size (D50) means that there are more agglomerates of carbon nanotubes, resulting in poorer dispersion. When the median particle size (D50) is greater than 250 μm, the possibility of agglomerates of carbon nanotubes in the electrode increases, and the overall conductivity of the electrode becomes uneven. On the other hand, when the median particle size (D50) is less than 10 μm, the conductivity decreases due to insufficient conductive pathways caused by shorter fiber lengths. When the median particle size (D50) is in the range of 10 μm to 250 μm, carbon nanotubes can be uniformly dispersed in the electrode while maintaining conductivity.

[0054] Furthermore, in the Raman spectrum of the aforementioned carbon nanotubes (B1), at 1560 cm⁻¹... -1 Above 1600cm -1 The maximum peak intensity is G within the following range, at 1310 cm⁻¹. -1 Above 1350cm -1 The G / D ratio when the maximum peak intensity D is within the following range is generally 0.1 or more, preferably 0.4 or more, more preferably 0.6 or more, generally 5.0 or less, preferably 3.0 or less, more preferably 1.0 or less.

[0055] Here, when the G / D ratio is in the range of 0.1 to 5.0, there are fewer defects or crystal interfaces on the carbon surface, and the conductivity is more likely to be higher, which is preferred.

[0056] Furthermore, when carbon nanotubes (B1) are used as conductive pigments (B), the carbon nanotubes (B1) before and after pulverization in step 1 preferably satisfy the following (1) and (2).

[0057] (1) With 1560cm -1 Above 1600cm -1 The maximum peak intensity is G within the following range, at 1310 cm⁻¹. -1 Above 1350cm -1 The G / D ratio of carbon nanotubes (B1) before pulverization is 0.1 to 5.0 when the maximum peak intensity is D in the following range.

[0058] (2) When the G / D ratio of the carbon nanotubes (B1) before pulverization is α and the G / D ratio of the carbon nanotubes (B1) after pulverization is β, β / α < 1.00.

[0059] Furthermore, the value of β / α decreases as the pulverization process proceeds, typically β / α < 1.00, preferably 0.50 < β / α < 1.00, more preferably 0.70 < β / α < 0.98, and even more preferably 0.90 < β / α < 0.96.

[0060] When β / α is within the above range, the pulverized surface can be activated appropriately with a shorter pulverization time, resulting in good dispersibility and storage stability in the dispersion process of step 2 described later, and the coating film can achieve excellent conductivity and finished product properties.

[0061] Other conductive pigments (B2) Other conductive pigments (B2) besides carbon nanotubes (B1) may include, for example, conductive carbon selected from at least one of acetylene black, channel black, furnace black, thermal cracking black, graphene, and graphite. Preferably, it is selected from one or more of acetylene black, channel black, furnace black, and thermal cracking black; more preferably, it is selected from one or more of acetylene black and channel black; and even more preferably, it is acetylene black.

[0062] The average primary particle size of the other conductive pigment (B2) is, for example, 10 nm or more, preferably 20 nm or more, preferably 80 nm or less, and more preferably 70 nm or less. Here, the average primary particle size refers to the average primary particle size obtained by directly averaging the diameters of 100 particles by observing the conductive pigment (B2) with an electron microscope, measuring the projected area of ​​each of 100 particles, calculating the diameter of an assumed circle with the same area, and then averaging the diameters of those 100 particles. Furthermore, when the pigment is in an aggregated state, the calculation is performed using the primary particles constituting the aggregated particles.

[0063] There is no particular limitation on the BET specific surface area of ​​other conductive pigments (B2). Based on the relationship between viscosity and conductivity, for example, 1m²... 2 / g or more, preferably 10m 2 / g or more, preferably 20m 2 / g or more, for example, 500m 2 / g or less, preferably 250m 2 / g or less, more preferably 200m 2 / g or less.

[0064] There is no particular limitation on the oil absorption of dibutyl phthalate (DBP) in other conductive pigments (B2). Based on the relationship between pigment dispersibility and conductivity, for example, it is 60 ml / 100g or more, preferably 150 ml / 100g or more, for example, 1,000 ml / 100g or less, preferably 800 ml / 100g or less.

[0065] Crushing methods and crushers The conductive pigment (B) described above is pulverized (including depolymerization) using a pulverizer. In this invention, carbon nanotubes are particularly preferred as the conductive pigment (B).

[0066] In the pulverizing step of process 1, a pulverizer containing pulverizing media such as glass beads, zirconia beads, and steel balls is used for pulverization. Pulverization is carried out using the pulverizing or destructive force generated by the collision between the pulverizing media and / or the collision between the pulverizer and the pulverizing media. As a pulverizing device, known pulverizing devices such as high-speed rotary impact mills, jet mills, roller mills, attritors, ball mills, vibratory mills, and bead mills can be used.

[0067] Furthermore, the surface activation or activity of the conductive pigment (B) can be adjusted by blowing various steam or gases into the pulverizer during pulverization. The steam is preferably an acidic or alkaline compound, and the gas is preferably oxygen, nitrogen, etc.

[0068] The aforementioned pulverization is preferably carried out using so-called dry dispersion. Here, "dry dispersion" means pulverizing the pigment without any liquid components. Since energy can be directly applied to the pigment, efficient and powerful pulverization (deagglomeration) can be achieved. Furthermore, because the pulverized surface is activated and interacts with the surrounding substances, good dispersibility and storage stability can be obtained in the dispersion process of step 2 described later, and the resulting coating film can achieve excellent conductivity and finished product properties.

[0069] The outer diameter of the pulverizing medium is preferably 0.1 mm to 5 mm, more preferably 0.5 mm to 3 mm. Within the above range, the desired pulverizing force can be obtained. When the conductive pigment (B) is carbon nanotube, the pigment can be effectively pulverized and depolymerized without excessively damaging the fiber shape.

[0070] Process 2 (Distributed Process) Step 2 involves mixing and dispersing the conductive pigment composition obtained in Step 1 with components containing pigment dispersion resin (A), solvent (C), and fluororesin (D) which may be included as needed. Through Step 2, a liquid conductive pigment slurry can be obtained.

[0071] The upper limit of the solid component concentration of the conductive pigment paste is generally less than 80% by mass, preferably less than 50% by mass, more preferably less than 20% by mass, and even more preferably less than 10% by mass. The lower limit is generally 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more.

[0072] The conductive pigment slurry is a slurry containing a pigment dispersion resin (A), a conductive pigment (B), a solvent (C), and a fluororesin (D) which may be included as needed. The pigment dispersion resin (A) preferably has at least one polar functional group selected from amide, imide, hydroxyl, carboxyl, sulfonic acid, phosphoric acid, silanol, cyano, pyrrolidone, and amino groups, and the concentration of the polar functional group of the pigment dispersion resin (A) is preferably 0.3 mmol / g or more and 23 mmol / g or less.

[0073] Furthermore, it is preferable to further include a highly polar, low molecular weight component (E) as needed.

[0074] In the dispersion process of step 2, conventionally known dispersers such as paint shakers, sand mills, ball mills, pebble mills, LMZ mills, DCP bead mills, planetary ball mills, homogenizers, twin-shaft mixers, and thin-film gyratory high-speed mixers (manufactured by FILMIX Corporation, trade name "CLEARMIX", etc.) can be used to uniformly mix and disperse the above components to prepare the product.

[0075] In addition, there is no particular requirement for the order in which the ingredients are mixed.

[0076] Pigment dispersion resin (A) The pigment dispersion resin (A) preferably has at least one alkyl group having 12 or more carbon atoms. The alkyl group having 12 or more carbon atoms may be any alkyl group (hydrocarbon group) known to the public, without particular limitation, preferably a straight-chain or branched alkyl group, and more preferably a straight-chain alkyl group.

[0077] As the alkyl group having 12 or more carbon atoms, it is preferred to have an alkyl group having 12 or more carbon atoms but less than 30 carbon atoms, more preferably an alkyl group having 15 or more carbon atoms but less than 26 carbon atoms, and even more preferably an alkyl group having 19 or more carbon atoms but less than 24 carbon atoms.

[0078] The alkyl group having 12 or more carbon atoms can be introduced into the resin, for example, by (co)polymerization of a polymerizable monomer containing alkyl groups having 12 or more carbon atoms.

[0079] Examples of polymerizable monomers containing alkyl groups having 12 or more carbon atoms include lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, behenyl (meth)acrylate, lauryl (meth)acrylamide, stearyl (meth)acrylamide, behenyl (meth)acrylamide, etc. These can be used alone or in combination of two or more.

[0080] It is generally believed that pigment dispersion resin (A) with large side chains such as alkyl groups having more than 12 carbon atoms can improve pigment dispersibility and storage stability through stereorepulsion.

[0081] Furthermore, the pigment dispersion resin (A) preferably has at least one polar functional group selected from amide, imide, hydroxyl, carboxyl, sulfonic acid, phosphoric acid, silanol, cyano, pyrrolidone, and amino groups. When the pigment dispersion resin (A) has polar functional groups, the concentration of these polar functional groups is preferably 0.3 mmol / g or more and 23 mmol / g or less. Additionally, the aforementioned acid groups may also be salts.

[0082] Preferably, at least amide, hydroxyl, carboxyl, sulfonic acid, phosphate and amino groups are used as polar functional groups, and more preferably at least hydroxyl, carboxyl and amino groups are used.

[0083] The type of resin can be any resin other than the fluoropolymers (D) described later, without any particular limitation. Examples include acrylic resins, polyester resins, epoxy resins, polyether resins, alkyd resins, polyurethane resins, polyvinyl alcohol, polyvinyl acetal, polyvinylpyrrolidone, polyvinyl acetate, silicone resins, polycarbonate resins, chlorinated resins, and their composite resins. These resins can be used alone or in combination of two or more.

[0084] From the viewpoints of pigment dispersibility, storage stability and finished product properties, the pigment dispersion resin (A) preferably contains an ethylene (co)polymer (A1) obtained by polymerizing or copolymerizing a monomer including a monomer containing a polymerizable unsaturated group of the following formula (1), and more preferably an acrylic resin obtained by (co)polymerizing a monomer containing a polymerizable unsaturated group of at least one (meth)acryloyl group.

[0085] Furthermore, the term "(co)polymer" in this invention includes both polymers obtained by polymerizing one monomer and copolymers obtained by copolymerizing two or more monomers.

[0086] C(-R)2=C(-R)2···Equation (1) [In the above formulas, R can be the same or different, and can be a hydrogen atom or an organic group.] Examples of the aforementioned ethylene (co)polymers (A1) include ethylene (co)polymers containing hydroxyl groups, ethylene (co)polymers containing carboxyl groups, ethylene (co)polymers containing amide groups, ethylene (co)polymers containing sulfonic acid groups, ethylene (co)polymers containing phosphate groups, ethylene (co)polymers containing pyrrolidone groups, and ethylene (co)polymers containing amino groups. These (co)polymers can be used alone or in combination of two or more.

[0087] Examples of ethylene (co)polymers containing hydroxyl groups include poly(meth)acrylate hydroxyethyl acrylate, polyvinyl alcohol, vinyl alcohol-vinyl fatty acid ester copolymers, vinyl alcohol-ethylene copolymers, vinyl alcohol-(N-vinylformamide) copolymers, hydroxyethyl (meth)acrylate, and copolymers of other polymerizable unsaturated monomers. The vinyl alcohol units in the (co)polymer can be obtained by hydrolyzing the vinyl fatty acid ester units after (co)polymerization.

[0088] Examples of carboxyl-containing ethylene (co)polymers include polymers of (meth)acrylic acid or copolymers of poly(meth)acrylic acid and other polymerizable unsaturated monomers.

[0089] Examples of amino-containing ethylene (co)polymers include polymers of (meth)acrylamide or copolymers of (meth)acrylamide and other polymerically unsaturated monomers.

[0090] Examples of ethylene (co)polymers containing sulfonic acid groups include polymers of allyl sulfonic acid or styrene sulfonic acid, and copolymers of allyl sulfonic acid and / or styrene sulfonic acid with other polymerizable unsaturated monomers.

[0091] Examples of ethylene (co)polymers containing phosphate groups include polymers of (meth)acryloyloxyalkyl phosphates or copolymers of (meth)acryloyloxyalkyl phosphates and other polymerically unsaturated monomers.

[0092] Examples of amino-containing ethylene (co)polymers include N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, and copolymers of other polymerizable unsaturated monomers.

[0093] Other polymerizable unsaturated monomers that can be copolymerized include, for example, vinyl formate, vinyl acetate, vinyl propionate, isopropylene acetate, vinyl valerate, vinyl octanoate, vinyl decanoate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl tert-carbonate, vinyl tert-valerate, and other carboxylic acid vinyl ester monomers; olefins such as ethylene, propylene, and butene; aromatic ethylenes such as styrene and α-methylstyrene; methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, and so on. Acrylic acid alkyl ester monomers such as 2-ethylhexyl methacrylate, dimethyl fumarate, dimethyl maleate, diethyl maleate, and diisopropyl itaconic acid; vinyl ether monomers such as methyl vinyl ether, n-propyl vinyl ether, isobutyl vinyl ether, and dodecyl vinyl ether; halogenated vinyl monomers or vinylidene monomers such as vinyl chloride, vinylidene chloride, vinyl fluoride, and vinylidene fluoride; allyl compounds such as allyl acetate and allyl chloride; and monomers containing quaternary ammonium groups such as 3-(meth)acrylamidopropyltrimethylammonium chloride. These monomers can be used alone or in combination of two or more.

[0094] The concentration of polar functional groups in the pigment dispersion resin (A) is typically 0.3 mmol / g to 23 mmol / g from the viewpoint of pigment dispersibility, storage stability and compatibility with solvent, preferably 0.3 mmol / g to 12 mmol / g, more preferably 0.4 mmol / g to 8.0 mmol / g, even more preferably 0.4 mmol / g to 6.0 mmol / g, and even more particularly preferably 0.4 mmol / g to 2.0 mmol / g.

[0095] The polymerization method of the above-mentioned ethylene (co)polymer (A1) can be used to manufacture it by polymerization methods that are known to them, such as solution polymerization, but it is not limited to this, and bulk polymerization, emulsion polymerization or suspension polymerization can also be used. When solution polymerization is carried out, it can be either continuous polymerization or batch polymerization. The monomer can be added all at once, in batches, continuously or intermittently.

[0096] There are no particular limitations on the polymerization initiators used in solution polymerization. Specifically, azo compounds such as azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), azobis-2,4-dimethylpentanitrile, and azobis(4-methoxy-2,4-dimethylpentanitrile) can be used; peroxides such as acetyl peroxide, benzoyl peroxide, lauroyl peroxide, acetylcyclohexylsulfonyl peroxide, and 2,4,4-trimethylpentyl-2-peroxyphenoxyacetic acid ester can be used; percarbonates such as diisopropyl peroxide, di-2-ethylhexyl peroxide, and diethoxyethyl peroxide; perester compounds such as tert-butyl peroxyneodecanate, α-cumyl peroxyneodecanate, and tert-butyl peroxyneodecanate; and well-known free radical polymerization initiators such as azobismethylpentanitrile and azobismethoxypentanitrile can be used.

[0097] There is no particular limitation on the polymerization reaction temperature; it can usually be set to a range of approximately 30°C to 200°C.

[0098] The degree of polymerization of the ethylene (co)polymer (A1) obtained in the above manner is, for example, 100 or more, preferably 150 or more, for example 4,000 or less, preferably 3,000 or less, and more preferably 700 or less.

[0099] Furthermore, the weight-average molecular weight is, for example, 1,000 or more, preferably 2,000 or more, more preferably 7,000 or more, for example, 2,000,000 or less, preferably 1,000,000 or less, more preferably 500,000 or less.

[0100] Furthermore, the weight-average molecular weight in this specification, unless otherwise specified, is the value obtained by converting the retention time (retention capacity) determined using gel permeation chromatography (GPC) to the molecular weight of polystyrene by measuring the retention time (retention capacity) of a standard polystyrene with a known molecular weight under the same conditions. Specifically, for gel permeation chromatography, "HLC8120GPC" (manufactured by Tosoh Corporation, trade name) can be used, and four columns, "TSKgel G-4000HXL", "TSKgel G-3000HXL", "TSKgel G-2500HXL" and "TSKgel G-2000HXL" (all manufactured by Tosoh Corporation, trade names), can be used. The determination is performed under the following conditions: mobile phase tetrahydrofuran, measurement temperature 40°C, flow rate 1 mL / min, and detector RI.

[0101] The above-mentioned ethylene (co)polymer (A1) can be prepared into a solid or a resin solution substituted with any solvent by desolventizing and / or solvent substitution after the synthesis is completed.

[0102] As a method for solvent removal, it can be carried out by heating under normal pressure or by removing the solvent under reduced pressure. As a method for solvent substitution, a substitute solvent can be added at any stage before, during, or after solvent removal.

[0103] Furthermore, when the content of alkyl groups with 12 or more carbon atoms in the dispersion resin (A) is ethylene (co)polymer (A1), the mass ratio of the monomer when the total monomers are 100% by mass is preferably 1 to 100% by mass, more preferably 10 to 90% by mass, even more preferably 20 to 80% by mass, and particularly preferably 30 to 60% by mass.

[0104] Furthermore, the content of alkyl groups having 12 or more carbon atoms can be calculated based on the mass ratio of the compound if a compound having 12 or more carbon atoms is subsequently added to the resin.

[0105] When the pigment dispersion resin (A) is solubilized from a solid state, from the viewpoint of solubility in a solvent, it is preferable to mix and dissolve it in a solvent that has been preheated to a liquid temperature of 60°C or higher (preferably 80°C or higher) (upper limit 200°C or lower, preferably 100°C or lower) to solubilize the resin, and then further mix it with other components (components (B), (C), (D) etc.).

[0106] In addition, the so-called "liquid temperature" refers to the temperature of the solvent or resin solution during dissolution.

[0107] Solid pigment dispersion resin (A) can be mixed into a solvent preheated to above 60°C and dissolved. Alternatively, solid pigment dispersion resin (A) can be mixed with a solvent and then heated to above 60°C.

[0108] In addition, it may contain components other than pigment dispersion resin (A) and solvent.

[0109] The solvent used may be used alone or in combination of two or more, and the types of solvents listed in (C) below are preferred.

[0110] The solid content of the pigment dispersion resin (A) is based on 100% by mass of the total solid content of the conductive pigment slurry, for example, 0.1% by mass or more, preferably 1% by mass or more, more preferably 3% by mass or more, for example, 40% by mass or less, preferably 30% by mass or less, more preferably 20% by mass or less.

[0111] Furthermore, the solid content of the pigment dispersion resin (A) is based on 100% by mass of the total amount of conductive pigment slurry, for example, 0.1% by mass or more, preferably 0.4% by mass or more, more preferably 0.7% by mass or more, for example, 10% by mass or less, preferably 5% by mass or less, more preferably 2% by mass or less.

[0112] Furthermore, the solid content of the pigment dispersion resin (A) is based on 100% by mass of the conductive pigment (B), for example, 0.1% by mass or more, preferably 1% by mass or more, more preferably 5% by mass or more, for example, 150% by mass or less, preferably 120% by mass or less, more preferably 80% by mass or less.

[0113] Solvent (C) The solvent (C) can preferably be water or various organic solvents.

[0114] Specifically, examples include hydrocarbon solvents such as n-butane, n-hexane, n-heptane, n-octane, cyclopentane, cyclohexane, and cyclobutane; aromatic solvents such as toluene and xylene; ketone solvents such as methyl isobutyl ketone; ether solvents such as n-butyl ether, dioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and diethylene glycol; ester solvents such as ethyl acetate, n-butyl acetate, isobutyl acetate, ethylene glycol monomethyl ether acetate, and butyl carbitol acetate; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and diisobutyl ketone; alcohol solvents such as ethanol, isopropanol, n-butanol, sec-butanol, and isobutanol; and amide solvents such as Equamide (an amide solvent manufactured by Idemitsu Kosan Co., Ltd., trade name), N,N-dimethylformamide, N,N-dimethylacetamide, N-methylformamide, N-methylacetamide, N-methylpropionamide, and N-methyl-2-pyrrolidone.

[0115] The preferred solvents are amide-based, with N-methyl-2-pyrrolidone being more preferred. These solvents may be used alone or in combination of two or more.

[0116] Furthermore, from the viewpoint of ensuring pigment dispersibility in conductive pigment pastes or preventing deterioration or hydrolysis of resin components, it is preferable that the paste is substantially water-free. Here, "substantially water-free" means that, based on 100% by mass of the total amount of conductive pigment paste, the water content is typically 1% by mass or less, preferably 0.5% by mass or less, and particularly preferably 0.1% by mass or less.

[0117] In this invention, the moisture content of the conductive pigment paste can be determined by Karl Fischer electrostatic titration. Specifically, a Karl Fischer moisture meter (manufactured by Kyoto Electronics Co., Ltd., trade name "MKC-610") can be used, with the set temperature of the moisture vaporization device (manufactured by Kyoto Electronics Co., Ltd., trade name "ADP-611") equipped in the device set to 130°C.

[0118] When using amide compounds (solvents) such as N-methyl-2-pyrrolidone, amine components are sometimes present as impurities. In the conductive pigment paste of the present invention, these amine components, as impurities, sometimes cause differences in viscosity or thickening tendency between different batches.

[0119] Furthermore, when the conductive pigment paste of the present invention is used to form an electrode layer by the method described later, although the solvent and the like will evaporate without leaving any residue, it is preferable to recycle and reuse the evaporated solvent in order to reduce waste, protect the environment, and / or reduce raw material costs. That is, it is preferable to use recycled solvent (C). This recycled solvent (recycled product) will also contain amine compounds (E1) that are already present in the conductive pigment paste of the present invention, which will also cause differences in the viscosity or thickening tendency of the conductive pigment paste between different batches. In addition, amine compounds usually have a strong odor.

[0120] Therefore, it is preferable to manage and adjust the content of amine compounds in the solvent (C) used as a recycled product to a certain amount or less. The content of amine compounds is usually less than 1% by mass, preferably less than 0.5% by mass, and particularly preferably less than 0.1% by mass.

[0121] In addition, the content of amine compounds can be quantified by conventional analyses such as ion chromatography-mass spectrometry (IC-MS). Quantification can be achieved by pre-creating calibration curves targeting the peak values ​​of the types of amines expected to be mixed in.

[0122] Furthermore, the phrase "using recycled material as solvent (C)" refers to the use of recycled material in the conductive pigment paste of the present invention, where the solvent (C) contains 10% by mass or more (preferably 20% by mass or more).

[0123] The content of solvent (C) in the conductive pigment paste is based on 100% by mass of the total amount of conductive pigment paste, for example, 40% by mass or more, preferably 60% by mass or more, more preferably 80% by mass or more, for example, 99% by mass or less, preferably 98% by mass or less, more preferably 97% by mass or less.

[0124] Furthermore, the solid component of the conductive pigment paste is based on 100% by mass of the total amount of the conductive pigment paste, for example, 1% by mass or more, preferably 2% by mass or more, and more preferably 3% by mass or more.

[0125] Fluoropolymer (D) The fluororesin (D) is a resin intended to form a film for electrode layers, and may be contained in conductive pigment slurry as needed, preferably.

[0126] Furthermore, it is an essential component for the composite slurry described later.

[0127] As a fluoropolymer (D), polyvinylidene fluoride (PVDF) is particularly preferred, and it can be used alone or in combination of two or more. Furthermore, PVDF can be modified in various ways, and from the viewpoint of adhesion to the substrate, it is preferred to have polar functional groups.

[0128] Fluoropolymer (D) may be present during pigment dispersion or added after pigment dispersion. Additionally, it may be present during the manufacture of the composite slurry described later.

[0129] From the viewpoint of adhesion to the substrate, reinforcement of film properties and solvent resistance, the weight-average molecular weight of the fluoropolymer (D) is, for example, 100,000 or more, preferably 500,000 or more, more preferably 650,000 or more, for example, 3,000,000 or less, and preferably 2,000,000 or less.

[0130] When fluororesin (D) is present, the content is based on 100% by mass of the solid content of the conductive pigment paste, for example, 10.0% by mass or more, preferably 30.0% by mass or more, more preferably 40.0% by mass or more, for example, 99.0% by mass or less, preferably 80.0% by mass or less, more preferably 60.0% by mass or less. Furthermore, based on 100% by mass of the total amount of the conductive pigment paste, the content is based on 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 1% by mass or more, for example, 10% by mass or less, preferably 7% by mass or less, more preferably 5% by mass or less.

[0131] When fluoropolymer (D) is solubilized from a solid state, from the viewpoint of solvent solubility, it is preferable to mix and dissolve it in a solvent that has been preheated to a liquid temperature of 40°C or higher (preferably 60°C or higher, more preferably 80°C or higher) (up to 200°C or lower, preferably 100°C or lower) to solubilize the resin, and then further mix and disperse it with the conductive pigment composition.

[0132] In addition, "liquid temperature" refers to the temperature of the solvent or resin solution during dissolution.

[0133] Solid fluoropolymer (D) can be dissolved by mixing it into a solvent preheated to above 40°C. Alternatively, solid fluoropolymer (D) can be mixed with a solvent first, and then heated to above 40°C.

[0134] In addition, it may contain components other than fluoropolymers (D) and solvents.

[0135] When performing the above-mentioned thermal dissolution, the fluoropolymer (D) is preferably polyvinylidene fluoride (or a modified form thereof).

[0136] The solvent used may be used alone or in combination of two or more, and the solvents listed above as solvents (C) are preferred.

[0137] Furthermore, as described above, it is preferable to cool the resin solution obtained by thermal dissolution to a specified temperature of 10°C or higher and below 40°C. From the viewpoint of preventing precipitation, this cooling process is described by the following formula: Cooling rate = (solution temperature at the start of cooling - solution temperature at the end of cooling) / cooling time The defined cooling rate is preferably 0.5°C / min or higher (preferably 1°C / min or higher).

[0138] Highly polar, low molecular weight components (E) The high polarity low molecular weight component (E) is a component used to improve the wettability and / or storage stability of conductive pigments, such as basic or acidic components known to exist, preferably containing an amine compound (E1).

[0139] The content of amine compound (E1) in the above-mentioned high polarity low molecular weight component (E) is based on 100% by mass of the high polarity low molecular weight component (E), for example, 50% by mass or more, preferably 75% by mass or more, and more preferably 95% by mass or more.

[0140] Examples of the aforementioned amine compounds (E1) include, for example, ammonia, primary amines, secondary amines, and tertiary amines.

[0141] Examples of primary amines include ethylamine, n-propylamine, sec-propylamine, n-butylamine, sec-butylamine, isobutylamine, tert-butylamine, pentylamine, hexylamine, heptylamine, octylamine, decylamine, laurylamine, tetradecylamine, 1,2-dimethylhexylamine, 3-pentylamine, 2-ethylhexylamine, allylamine, aminoethanol, 1-aminopropanol, 2-aminopropanol, aminobutanol, aminopentanol, aminohexanol, 3-ethoxypropylamine, 3-propoxypropylamine, 3-isopropoxypropylamine, 3-butoxypropylamine, 3-isobutoxypropylamine, 3-(2-ethylhexyloxy)propylamine, aminocyclopentane, aminocyclohexane, aminonorbornene, aminomethylcyclohexane, aminobenzene, benzylamine, phenethylamine, α-phenylethylamine, and naphthylamine. Primary monoamines such as furfurylamine; ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,2-diaminobutane, 1,3-diaminobutane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, dimethylaminopropylamine, diethylaminopropylamine, bis-(3-aminopropyl)ether, 1,2-bis-(3-aminopropoxy)ethane, 1,3-bis-(3-aminopropoxy)-2,2'-dimethylpropane, aminoethylethanolamine, 1,2-diaminocyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, 1,3-diaminomethylcyclohexane 1,4-Diaminomethylcyclohexane, 1,3-Diaminoethylcyclohexane, 1,4-Diaminoethylcyclohexane, 1,3-Diaminopropylcyclohexane, 1,4-Diaminopropylcyclohexane, hydrogenated 4,4'-diaminodiphenylmethane, 2-aminopiperidine, 4-aminopiperidine, 2-aminomethylpiperidine, 4-aminomethylpiperidine, 2-aminoethylpiperidine, 4-aminoethylpiperidine, N-aminoethylpiperidine, N-aminopropylpiperidine, N-aminoethylmorpholine, N-aminopropylmorpholine, isophorone diamine, menthyl diamine, 1,4-diaminopropylpiperazine, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 2,4-toluenediamine, 2,6-toluenediamine 2,4-Diaminotoluene, m-aminobenzylamine, 4-chloro-o-phenylenediamine, tetrachloro-p-xylenediamine, 4-methoxy-6-methyl-m-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 1,5-naphthylenediamine, 2,6-naphthylenediamine, benzidine, 4,4'-bis(o-toluidine), o-anisidine, 4,4'-diaminodiphenylmethane, 2,2-(4,4'-diaminodiphenyl)propane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodibenzyl sulfone, methylene bis(o-chloroaniline), 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxazolo[5].[5] Undecane, diethylenetriamine, iminodipropylamine, methyliminodipropylamine, bis(hexamethylene)triamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, N-aminoethylpiperazine, N-aminopropylpiperazine, 1,4-bis(aminoethylpiperazine), 1,4-bis(aminopropylpiperazine), 2,6-diaminopyridine, bis(3,4-diaminophenyl)sulfone, and other primary polyamines, etc.

[0142] Examples of secondary amines include diethylamine, dipropylamine, di-n-butylamine, di-sec-butylamine, diisobutylamine, di-n-pentylamine, di-3-pentylamine, dihexylamine, dioctylamine, di(2-ethylhexyl)amine, methylhexylamine, diallylamine, pyrrolidine, piperidine, 2,4-dimethylpiperidine, 2,6-dimethylpiperidine, 3,5-dimethylpiperidine, diphenylamine, N-methylaniline, N-ethylaniline, dibenzylamine, and methylbenzylamine. Secondary monoamines such as naphthylamine, pyrrole, indoline, indole, and morpholine; N,N'-dimethylethylenediamine, N,N'-dimethyl-1,2-diaminopropane, N,N'-dimethyl-1,3-diaminopropane, N,N'-dimethyl-1,2-diaminobutane, N,N'-dimethyl-1,3-diaminobutane, N,N'-dimethyl-1,4-diaminobutane, and N,N'-dimethyl-1 5-Diaminopentane, N,N'-Dimethyl-1,6-Diaminohexane, N,N'-Dimethyl-1,7-Diaminoheptane, N,N'-Diethylethylenediamine, N,N'-Diethyl-1,2-Diaminopropane, N,N'-Diethyl-1,3-Diaminopropane, N,N'-Diethyl-1,2-Diaminobutane, N,N'-Diethyl-1,3-Diaminobutane, N,N Secondary polyamines such as '-diethyl-1,4-diaminobutane, N,N'-diethyl-1,6-diaminohexane, piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, 2,6-dimethylpiperazine, high-piperazine, 1,1-di-(4-piperidinyl)methane, 1,2-di-(4-piperidinyl)ethane, 1,3-di-(4-piperidinyl)propane, and 1,4-di-(4-piperidinyl)butane.

[0143] Examples of tertiary amines include trimethylamine, triethylamine, tri-n-propylamine, triisopropylamine, tri-1,2-dimethylpropylamine, tri-3-methoxypropylamine, tri-n-butylamine, triisobutylamine, tri-sec-butylamine, tri-pentylamine, tri-3-pentylamine, tri-n-hexylamine, tri-n-octylamine, tri-2-ethylhexylamine, tri-dodecylamine, tri-laurhodium, dicyclohexylethylamine, cyclohexyldiethylamine, tri-cyclohexylamine, N,N-dimethylhexylamine, N-methyldihexylamine, N,N-dimethylcyclohexylamine, N-methyldicyclohexylamine, N,N-diethylethanolamine, N,N-dimethylethanolamine, N-ethyldiethanolamine, triethanolamine, tribenzylamine, N,N-dimethylbenzylamine, diethylbenzylamine, triphenylamine, N,N-dimethylamino-p-cresol, and N,N-dimethylaminomethyl Phenol, 2-(N,N-dimethylaminomethyl)phenol, N,N-dimethylaniline, N,N-diethylaniline, pyridine, quinoline, N-methylmorpholine, N-methylpiperidine, 2-(2-dimethylaminoethoxy)-4-methyl-1,3,2-dioxaborane, 2-, 3-, 4-picoline and other tertiary monoamines; tetramethylethylenediamine, pyrazine, N,N'-dimethylpiperazine, N,N'-bis((2-hydroxy)propyl)piperazine, hexamethylenetetramine, N,N,N',N'-tetramethyl-1,3-butanediamine, 2-dimethylamino-2-hydroxypropane, diethylaminoethanol, N,N,N-tris(3-dimethylaminopropyl)amine, 2,4,6-tris(N,N-dimethylaminomethyl)phenol, heptamethylisobisguanidine and other tertiary polyamines, etc.

[0144] These can be used individually or in combination of two or more.

[0145] Primary amine compounds are preferred, and monovalent amine compounds (monamines) are even more preferred.

[0146] As the aforementioned amine compound (E1), examples include alkanolamines, aliphatic amines, alicyclic amines, and aromatic amines, all of which are preferred, with aromatic amines being the most preferred.

[0147] Ideally, no amine compounds should remain in the dried electrode layer. Therefore, the weight-average molecular weight of the amine compound (E1) is preferably less than 1,000, more preferably less than 800, further preferably less than 500, particularly preferably less than 350, and even more particularly preferably less than 250.

[0148] Furthermore, for the same reason, the boiling point of the amine compound is preferably below 400°C, more preferably below 300°C, and even more preferably below 200°C.

[0149] Furthermore, if the boiling point is low, it may volatilize during manufacturing or storage. From the viewpoint of odor, the lower limit is preferably 50°C or higher, and more preferably 100°C or higher.

[0150] Furthermore, the amine value of the amine compound (E1) is generally 5 mg KOH / g or more, preferably 50 mg KOH / g or more, more preferably 105 mg KOH / g or more, and generally in the range of 1,000 mg KOH / g or less.

[0151] As other highly polar, low molecular weight components, they can be used in combination with amine compounds (E1). For example, a highly polar, low molecular weight acidic component selected from organic and inorganic acids can be used alone or in combination with two or more. In addition, a highly polar, low molecular weight basic component selected from organic and inorganic bases can be used alone or in combination with two or more.

[0152] Organic acids include, for example, organic carboxylic acids (formic acid, acetic acid, propionic acid, benzoic acid, phthalic acid, etc.) and organic sulfonic acids (benzenesulfonic acid, etc.). Inorganic acids include, for example, hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, etc., and the anhydrides of these acids can also be used.

[0153] As organic bases, base components other than amine compounds can be listed separately; as inorganic bases, metal hydroxides (sodium hydroxide, potassium hydroxide, etc.) can be listed separately.

[0154] The content of the aforementioned high polarity low molecular weight component (E) is based on 100% by mass of the solid content of the conductive pigment paste, for example, 1% by mass or more, preferably 1.5% by mass or more, more preferably 2% by mass or more, for example, 600% by mass or less, preferably 300% by mass or less, more preferably 50% by mass or less.

[0155] Furthermore, based on 100% by mass of the solid content of the conductive pigment (B), the lower limit is, for example, 1% by mass or more, preferably 2% by mass or more, and more preferably 5% by mass or more. The upper limit is, for example, 1,000% by mass or less, preferably 500% by mass or less, and more preferably 50% by mass or less.

[0156] Furthermore, based on 100% by mass of the total amount of conductive pigment paste, the lower limit is, for example, 0.01% by mass or more, preferably 0.05% by mass or more, and more preferably 0.1% by mass or more. The upper limit is, for example, 10% by mass or less, preferably 5% by mass or less, and more preferably 1% by mass or less.

[0157] Highly polar, low molecular weight components (E) [especially amine compounds (E1)] often have strong odors, which can sometimes deteriorate the working environment during blending or drying. Furthermore, they are usually expensive and can sometimes increase costs. Therefore, they must be set to the minimum required concentration.

[0158] Furthermore, the ratio of solvent (C) to high polarity low molecular weight component (E), measured by mass ratio of solvent (C) to high polarity low molecular weight component (E), is typically in the range of 100 / 0.01 to 100 / 10, preferably in the range of 100 / 0.02 to 100 / 7, more preferably in the range of 100 / 0.05 to 100 / 5, and even more preferably in the range of 100 / 0.1 to 100 / 4.

[0159] Other ingredients As the conductive pigment paste, in addition to the components (A), (B), and (C) mentioned above, and (D) and (E) which may be included as needed, other components may also be included.

[0160] Other components may include, for example, resins other than pigment dispersion resin (A) and fluororesin (D), neutralizers, defoamers, preservatives, rust inhibitors, plasticizers, and pigments other than conductive pigments (B).

[0161] Pigments other than conductive pigments (B) include, for example, white pigments such as titanium dioxide and zinc white; blue pigments such as phthalocyanine blue and indanthrene blue; green pigments such as phthalocyanine green and verdigris; organic red pigments such as azo or quinacridone-based pigments and iron oxide red; organic yellow pigments such as benzimidazolone-based, isoindolineone-based, isoindoline-based, and quinacridone-based pigments, and yellow pigments such as titanium yellow and chrome yellow. These pigments can be used alone or in combination of two or more. These pigments other than conductive pigments (B) can be used for purposes such as color adjustment or film enhancement within a range that will not significantly affect conductivity. They can be dispersed simultaneously with pigment dispersion resin (A) and conductive pigment (B), or they can be mixed as pigments or pigment slurries after dispersing pigment dispersion resin (A) and conductive pigment (B) into a slurry.

[0162] The content of pigments other than the conductive pigment (B) is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 1% by mass or less, and particularly preferably substantially non-existent, based on 100% by mass of the total pigments in the conductive pigment slurry.

[0163] As for the viscosity of the aforementioned conductive pigment slurry, from the viewpoint of pigment dispersibility or storage stability, the shear rate is 2s. -1 The viscosity is, for example, less than 5,000 mPa·s, preferably less than 2,500 mPa·s, more preferably less than 1,000 mPa·s, for example, more than 10 mPa·s, preferably more than 50 mPa·s, more preferably more than 100 mPa·s.

[0164] Viscosity can be measured using, for example, a conical viscometer (manufactured by HAAKE, trade name "Mars2", 35 mm in diameter, 2° inclined conical plate).

[0165] [Manufacturing method of composite slurry (for lithium-ion secondary batteries)] Process 3 (Mixing process of electrode active materials) In the manufacturing method of the present invention, a conductive pigment slurry having conductive pigments is first prepared through steps 1 and 2. Further, as step 3 (the mixing step of electrode active materials), a composite slurry for lithium-ion secondary batteries can be manufactured by mixing the conductive pigment slurry with at least one electrode active material (F).

[0166] The solid content of the electrode active material (F) is based on 100% by mass of the total amount of the composite slurry, and is usually 10% by mass or more, preferably 20% by mass or more, usually 99% by mass or less, preferably 95% by mass or less, and is preferred from the perspective of battery performance.

[0167] In addition, fluoropolymer (D), which is an arbitrary component in the conductive pigment slurry, is an essential component in the composite slurry and must be contained therein.

[0168] The solid content of fluororesin (D) is based on 100% by mass of the total amount of the composite slurry, and is usually 0.05% by mass or more, preferably 0.1% by mass or more, usually 10% by mass or less, preferably 2% by mass or less, and is preferred from the perspective of battery performance, slurry viscosity, etc.

[0169] In the mixing process of step 3, conventional mixers and dispersers can be used to mix the composite slurry evenly.

[0170] The solid content of pigment dispersion resin (A) in the solid components of the above-mentioned composite slurry is based on 100% by mass of the total amount of composite slurry. It is usually 0.01% by mass or more, preferably 0.05% by mass or more, usually 10% by mass or less, preferably 1% by mass or less, and is preferred from the perspective of battery performance, slurry viscosity, etc.

[0171] In the composite slurry of the present invention, from the viewpoint of storage stability (thickening inhibition) of the composite slurry, a high polarity low molecular weight component (E) is contained, and as the high polarity low molecular weight component (E), at least one amine compound (E1) is preferably contained.

[0172] From the viewpoint of mitigating the aggregation of conductive pigment (B) and electrode active material (F) by contacting the highly polar, low molecular weight component (E) with the conductive pigment (B) (wetting it), and then mixing the electrode active material (F), the preferred order includes first mixing the conductive pigment (B) with the highly polar, low molecular weight component (E).

[0173] The solid content of the conductive pigment (B) in the solid component of the composite slurry of the present invention is, based on 100% by mass of the total amount of the composite slurry, typically 0.01% by mass or more, preferably 0.05% by mass or more, more preferably 0.1% by mass or more, typically 30% by mass or less, preferably 10% by mass or less, more preferably 5% by mass or less, which is preferred from the perspective of battery performance. Furthermore, the content of the solvent (C) in the composite slurry of the present invention is, based on 100% by mass of the total amount of the composite slurry, typically 1% by mass or more, preferably 4% by mass or more, more preferably 7% by mass or more, typically 90% by mass or less, preferably 70% by mass or less, more preferably 50% by mass or less, which is preferred from the perspective of electrode drying efficiency and slurry viscosity.

[0174] The above-mentioned composite slurry is preferably used for positive or negative electrode applications in lithium-ion secondary battery electrodes, and is preferably used for positive electrode applications.

[0175] Electrode active material (F) Examples of electrode active materials (F) include lithium nickel oxide (LiNiO2), lithium manganese oxide (LiMn2O4), and lithium cobalt oxide (LiCoO2). 1 / 3 Co 1 / 3 Mn 1 / 3 Lithium composite oxides such as O2; lithium iron phosphate (LiFePO4); sodium composite oxides; potassium composite oxides, etc. These electrode active materials (F) can be used alone or in combination of two or more. The above-mentioned electrode active materials containing lithium iron phosphate are preferred due to their low price and good cycle characteristics and energy density.

[0176] The particle size of the electrode active material is typically 0.5 μm or larger, preferably 10.5 μm or larger, typically 30 μm or smaller, and preferably 20 μm or smaller.

[0177] The solid content of electrode active material (F) in the 100% by mass of the solid component of the composite slurry for lithium-ion secondary battery electrodes of the present invention is usually 50% by mass or more, preferably 60% by mass or more, and less than 100% by mass, which is preferred from the perspective of battery capacity, battery resistance, etc.

[0178] When composite slurries contain the aforementioned electrode active material (F), they may sometimes become viscous during storage. The reason for this is generally believed to be that the electrode active material (F) has alkali metal hydroxides (such as LiOH, KOH, NaOH, etc.) from the raw materials on its particle surface, which causes aggregation (viscousening) due to the conductive pigments (B) with acidic surfaces. Therefore, by containing a certain amount or more of a high-polarity, low-molecular-weight component (E) [especially amine compounds (E1)], the viscousening of the composite slurry during storage can be suppressed.

[0179] Furthermore, the electrode active material (F) of the present invention may preferably be an electrode active material composite (F-1) whose surface is covered by at least a portion of carbon nanotubes.

[0180] The aforementioned composite (F-1) can be prepared by pre-mixing with electrode active material (F), carbon nanotubes and other components as needed (e.g., solvent or dispersion resin). A drying process can be added after mixing as needed to allow the carbon nanotubes to be more uniformly adsorbed and / or fixed on the electrode active material (F).

[0181] Furthermore, the electrode active material composite (F-1) manufactured as described above can form a uniform conductive network around the electrode active material by adsorbing and / or fixing carbon nanotubes onto the surface of the electrode active material.

[0182] As a carbon nanotube that can be used in the electrode active material complex (F-1), any carbon nanotube known in itself can be used without particular limitation, and the carbon nanotubes listed in the above carbon nanotubes (B1) are preferred.

[0183] [Lithium-ion secondary battery electrode] Method for fabricating electrode layers for lithium-ion secondary batteries As mentioned above, the electrode layer for lithium-ion secondary batteries (also known as the electrode composite material layer or composite material layer) can be manufactured by coating the core material (current collector) of the positive or negative electrode with a composite slurry for lithium-ion secondary batteries and then drying it, but it is particularly preferred for the positive electrode.

[0184] In addition, the conductive pigment paste obtained in the manufacturing method of the present invention can be used not only as a paste for the composite material layer (electrode layer), but also as a base layer (also called a functional layer or adhesive layer) between the electrode core material and the composite material layer (electrode layer).

[0185] The coating method for the composite slurry for lithium-ion secondary batteries can be implemented using methods already known, such as extrusion coating machines. The coating amount of the composite slurry for lithium-ion secondary batteries is not particularly limited, and can be set such that the thickness of the dried composite layer is, for example, 0.04 mm or more, preferably 0.06 mm or more, for example, 0.30 mm or less, and preferably 0.24 mm or less. The temperature for the drying process can be appropriately set, for example, 80°C or more, preferably 100°C or more, for example, 250°C or less, and preferably 200°C or less. The drying time can be appropriately set, for example, 5 seconds or more, for example, 120 minutes or less, and preferably 60 minutes or less.

[0186] In the above drying process, all or part of the solvent (C) and the high polarity low molecular weight component (E) that may be included as needed will evaporate. As mentioned above, in order to reduce waste, protect the environment and / or reduce raw material costs, it is preferable to recover and reuse the evaporated components (C) and (E).

[0187] Example The following examples illustrate the invention in more detail, but the invention is not limited to these specific embodiments. In the examples, "parts" refers to parts by mass, and "%" refers to percentages by mass.

[0188] [Manufacturing of Dispersion Resins] Manufacturing Example 1 75 parts of N-methyl-2-pyrrolidone (Note 1) were added to a reaction vessel equipped with a thermometer, temperature controller, stirrer, reflux condenser, and water separator, and heated to 120°C in a nitrogen atmosphere. After reaching 120°C, a mixture of the monomers listed in Table 1 (totaling 100 parts) and 2 parts of 2,2'-azobis(2-methylbutyronitrile) was added dropwise over 3 hours. After the addition was complete, the mixture was matured at 120°C for 30 minutes, and then a mixture of 1 part of 2,2'-azobis(2-methylbutyronitrile) and 20 parts of N-methyl-2-pyrrolidone (Note 1) was added dropwise over 1 hour. After further maturation at 120°C for 1 hour, the mixture was cooled, and N-methyl-2-pyrrolidone (Note 1) was added to obtain an acrylic resin (A1) with a solid content of 50%. The polar functional group concentration was 1.3 mmol / g.

[0189] (Note 1) N-Methyl-2-pyrrolidone: Moisture content 500 ppm (Note 2), amine content 500 ppm (Note 2), recycled product (Note 2) Moisture content and amine content were determined using a Karl Fischer moisture meter (Kyoto Electronics Co., Ltd., trade name "MKC-610") and an ion chromatograph (Shimadzu Corporation, trade name "prominence HIC-NS").

[0190] Manufacturing Example 2 Except for the monomer types used in Table 1 below, an acrylic resin (A2) with a solid content of 50% was obtained in the same manner as in Manufacturing Example 1.

[0191] In addition, the weight-average molecular weight values ​​of the obtained resins are recorded in Table 1 below. In the table, "Resin A1" means "acrylic resin (A1)" and "Resin A2" means "acrylic resin (A2)".

[0192] [Table 1]

[0193] The abbreviations for the monomer types in Table 1 above are as follows.

[0194] •SLMA: Lauryl methacrylate (a hydrocarbon group with 12 carbon atoms) • BEMA: Behenate methacrylate (with a 22-carbon hydrocarbon group) St: Styrene ·DMAEMA: N,N-dimethylaminoethyl methacrylate.

[0195] [Crushing of carbon nanotubes (CNTs)] Manufacturing Example 3 Using a continuous dry bead mill “DryStar SDA1” (manufactured by Ashizawa Finetech Co., Ltd.), carbon nanotubes (CNT1 (Table 2 below)) were pulverized for 1 hour at a feed rate of 0.5 kg / hr under the conditions of zirconia beads (diameter 3.0 mm), a filling rate of 70%, and a mill circumferential speed of 5.0 m / s, to obtain carbon nanotube pulverized product (C1-1).

[0196] The G / D ratio of the carbon nanotubes before pulverization was taken as α, and the G / D ratio after pulverization was taken as β, with β being 0.97. The G / D ratio was determined by the method described later.

[0197] Manufacturing Example 4 Using a continuous dry bead mill "DryStar SDA1" (manufactured by Ashizawa Finetech Co., Ltd.), carbon nanotubes (CNT1 (Table 2 below)) were pulverized for 2 hours at a feed rate of 0.5 kg / hr under the conditions of zirconia beads (diameter 3.0 mm), a filling rate of 70%, and a mill circumferential speed of 5.0 m / s, to obtain carbon nanotube pulverized product (C1-2).

[0198] The G / D ratio of the carbon nanotubes before pulverization was taken as α, and the G / D ratio after pulverization was taken as β, with β / α being 0.95. The G / D ratio was determined by the method described later.

[0199] Manufacturing Example 5 Using a continuous dry bead mill “DryStar SDA1” (manufactured by Ashizawa Finetech Co., Ltd.), carbon nanotubes (CNT2 (Table 2 below)) were pulverized for 2 hours at a feed rate of 0.5 kg / hr under the conditions of zirconia beads (diameter 3.0 mm), a filling rate of 70%, and a mill circumferential speed of 5.0 m / s, to obtain carbon nanotube pulverized product (C2-2).

[0200] The β / α ratio was 0.95, with the G / D ratio of the carbon nanotubes before pulverization as α and the G / D ratio after pulverization as β. The G / D ratio was determined by the method described later.

[0201] Manufacturing Example 6 Using a continuous dry bead mill “DryStar SDA1” (manufactured by Ashizawa Finetech Co., Ltd.), carbon nanotubes (CNT3 (Table 2 below)) were pulverized for 1 hour at a feed rate of 0.5 kg / hr under the conditions of zirconia beads (diameter 3.0 mm), a filling rate of 70%, and a mill circumferential speed of 5.0 m / s, to obtain carbon nanotube pulverized product (C3-1).

[0202] The β / α ratio was 0.97 when the G / D ratio of the carbon nanotubes before pulverization was taken as α and the G / D ratio after pulverization was taken as β. The G / D ratio was determined by the method described later.

[0203] [Table 2]

[0204] All of the above-mentioned carbon nanotubes are multilayer carbon nanotubes.

[0205] In addition, the median particle size (D50), G / D ratio, specific surface area (BET specific surface area) and acidic content in Table 2 above were determined by the methods described later.

[0206] [Manufacturing of Conductive Pigment Pastes and Composite Pastes] Example 1A In a container, 5000 parts of N-methyl-2-pyrrolidone (Note 1), 200 parts of pulverized carbon nanotubes (C1-2), 80 parts of polyvinylpyrrolidone as a dispersion resin (40 parts solids) (Note 3), 1800 parts of a resin solution of KF Polymer W#7300 (manufactured by KUREHA, trade name, polyvinylidene fluoride, weight average molecular weight 1 million) (180 parts solids) (Note 4), and 25 parts of benzylamine as an amine were mixed while stirring. The mixture was then adjusted to a total mass of 10000 parts by adding N-methyl-2-pyrrolidone (Note 1). The mixture was then dispersed in a ball mill for 4 hours to produce a conductive pigment slurry (A-1).

[0207] (Note 3) Polyvinylpyrrolidone: weight average molecular weight (Mw) 12000, polar functional group concentration 9.0 (mmol / g) (Note 4) The resin solution of polyvinylidene fluoride is obtained by mixing and dissolving polyvinylidene fluoride with N-methyl-2-pyrrolidone (Note 1) at a temperature of 80°C, and then cooling to 30°C for 40 minutes.

[0208] Examples 2A-10A, Comparative Examples 1A-2A Except that the dispersion resin, carbon nanotubes (CNTs) and amine are formulated according to the formulation in Table 3 below, conductive pigment slurries (A-2) to (A-12) are obtained in the same manner as in Example 1A.

[0209] In addition, uncrushed (dry dispersed) carbon nanotubes [CNT1 (C1-0)] were used in the comparative examples.

[0210] Furthermore, the results of the evaluation tests for the conductive pigment pastes described later are recorded in Table 3 below.

[0211] [Table 3]

[0212] The amount of dispersion resin in Table 3 above refers to the solid component value.

[0213] The composition of the dispersion resin in Table 3 above is as follows.

[0214] • Polyvinyl butyral: Average degree of polymerization 600, hydroxyl content 12 mol%, butyral content 87 mol%, acetyl content 1 mol%, polar functional group concentration 1.0 (mmol / g) • Polymethyl methacrylate: a homopolymer of methyl methacrylate with a weight average molecular weight of 20,000 and a polar functional group concentration of 0 (mmol / g).

[0215] The boiling points and molecular weights of the amines in Table 3 above are shown below.

[0216] ·Benzylamine: Boiling point 185℃, molecular weight 107 • Aminomethylpropanol: Boiling point 166℃, molecular weight 89.

[0217] Example 1B Relative to 100 parts of the conductive pigment paste (A-1) mentioned above, 900 parts of electrode active material particles (in the form of LiNi) were dispersed using a disperser. 0.5 Mn 1.5 The spinel-structured lithium nickel manganese oxide particles, represented by O4, have an average particle size of 6 μm and a BET specific surface area of ​​0.7 m². 2 The composite slurry (B-1) was prepared by mixing ( / g) with other ingredients.

[0218] Examples 2B-10B, Comparative Examples 1B-2B Except for the formulations in Table 4 below, composite slurries (B-2) to (B-12) were obtained in the same manner as in Example 1B.

[0219] Furthermore, the results of the evaluation tests of the composite slurry described later are recorded in Table 3 above.

[0220] [Table 4]

[0221] <Median particle size (D50)> The median particle size (D50) was determined using a laser diffraction / scattering particle size distribution measuring device “LA-960” (manufactured by HORIBA Corporation, trade name) through the following steps.

[0222] [Preparation of Aqueous Dispersion Media] Add 0.10 g of F10MC (manufactured by Nippon Paper Corporation, trade name: sodium carboxymethyl cellulose (hereinafter also referred to as CMCNa)) to 100 mL of distilled water and stir at room temperature for more than 24 hours to dissolve it, thus preparing an aqueous dispersion medium of 0.1% by mass of CMCNa.

[0223] [Preparation of CMCNa aqueous solution] Add 2.0 g of F10MC (manufactured by Nippon Paper Corporation, trade name: sodium carboxymethyl cellulose) to 100 mL of distilled water and stir at room temperature for more than 24 hours to dissolve it, thus preparing an aqueous solution of CMCNa 2.0% by mass.

[0224] [Pretreatment before assay] Weigh 6.0 mg of carbon nanotubes into a vial and add 6.0 g of the above-mentioned aqueous dispersion medium. Pretreatment was performed using an ultrasonic homogenizer (MICROTEC·NITI-ON, "SmurtNR-50"). After confirming no chip degradation, the chip was immersed at least 10 mm above the sample liquid surface. The TIME SET (irradiation time) was set to 40 seconds, the POW SET to 50%, and the START POW to 50% (output power 50%). A homogenized carbon nanotube aqueous dispersion was prepared by ultrasonic irradiation with an automatic power operation based on constant output power.

[0225] [Measurement] Using the above-mentioned carbon nanotube aqueous dispersion, the proportion of dispersed particles smaller than 1 μm and the median particle size (D50) of carbon nanotubes were determined according to the following method.

[0226] The optical model of the LS 13 320 general liquid module was set to a refractive index of 1.520 for carbon nanotubes and 1.333 for water. After cleaning the module, approximately 1.0 mL of CMCNa aqueous solution was added.

[0227] Under a pump speed of 50%, after offset measurement, optical axis adjustment, and background measurement, the prepared carbon nanotube aqueous dispersion was added to a particle size analyzer. The dispersion was prepared by adding the relative concentration (representing the percentage of light scattered outside the beam due to particles) to a particle size analyzer to a concentration of 8–12% or a PIDS (partial particle size distribution) of 40–55%. The dispersion was then subjected to ultrasonic irradiation at 78 W for 2 minutes (pretreatment) using an accessory device of the particle size analyzer. After 30 seconds of circulation to remove air bubbles, the particle size distribution was measured. A graph of volume % relative to particle size (particle diameter) was obtained, and the proportion of dispersed particles smaller than 1 μm and the median particle size (D50) were determined.

[0228] For the measurement, for each carbon nanotube sample, three samples were collected by changing the sampling location to determine the particle size distribution, and the proportion of dispersed particles below 1 μm and the average value of the median particle size (D50) were obtained.

[0229] <G / D ratio of carbon nanotubes> The Raman spectra of carbon nanotubes were measured using a 532 nm laser wavelength by mounting carbon nanotubes on a Raman microscope (manufactured by Horiba Manufacturing Co., Ltd., trade name "XploRA"). Within the obtained peak values, the spectra at 1560 cm⁻¹ were analyzed. -1 Above ~1600cm -1 The maximum peak intensity is G within the following range, at 1310 cm⁻¹. -1 Above ~1350cm -1 The G / D ratio of carbon nanotubes is defined as the maximum peak intensity D within the following range.

[0230] <Specific Surface Area (BET Specific Surface Area)> The BET specific surface area of ​​carbon nanotubes can be measured according to Japanese Industrial Standard JIS Z8830:2013 using a specific surface area measuring device (BERSORP-MAX (Microtrac·BEL Co., Ltd.)). 2 / g).

[0231] <Acidity of carbon nanotubes (CNTs)> Accurately weigh 2 g of CNTs and immerse them in 50 ml of a 0.01 M benzylamine / n-methylpyrrolidone solution. Disperse the solution using an ultrasonic irradiation device for 1 hour. Then, centrifuge and filter the supernatant. Quantitatively analyze the residual benzylamine in the filtrate by potentiometric titration with 0.1 M hydrochloric acid to determine the acidic basis (mmol / g) per 1 g of CNTs.

[0232] Evaluation test Evaluation tests were conducted on the conductive pigment pastes and composite pastes obtained in the above embodiments and comparative examples. Even if only one evaluation result is unsatisfactory, the evaluation is considered unsatisfactory.

[0233] <Dispersion> According to the dispersibility test of Japanese Industrial Standard JIS K-5600-2-5, the dispersibility of the obtained conductive pigment paste is evaluated using a particle size analyzer according to the following standards. C and D are considered unqualified.

[0234] A: The pigments are dispersed below 10μm. The dispersibility is excellent.

[0235] B: The pigments are dispersed with a particle size greater than 10μm and less than 20μm. The dispersibility is slightly better.

[0236] C: The pigments are dispersed at a size of 20μm or larger, and aggregates cannot be visually identified. Dispersibility is slightly poor.

[0237] D: Visually confirm the agglomerates. The dispersibility is extremely poor.

[0238] <Volume resistivity (conductivity)> The obtained conductive pigment paste was further subjected to a volume resistivity measurement. In the volume resistivity measurement, a 5% by mass solution of polyvinylidene fluoride (manufactured by KUREHA, trade name "KF Polymer W#7300", solvent: N-methyl-2-pyrrolidone) was used as a binder.

[0239] The conductive pigment slurry and KF Polymer W#7300 solution were measured in a ratio of 5:100, with the total mass of conductive pigment (B) in the conductive pigment slurry and the solid components of pigment dispersion resin (A) and KF Polymer W#7300 in the conductive pigment slurry being mixed in an ultrasonic homogenizer for 2 minutes to obtain a sample for testing.

[0240] The test sample was coated onto a glass plate (2mm × 100mm × 150mm) using a doctor blade coating method and dried at 80°C for 60 minutes to form a coating film. After measuring the film thickness, the resistance was measured using an ASP probe (Mitsubishi Chemical Analytech, trade name "MCP-TP03P") and a resistivity meter (Mitsubishi Chemical Analytech, trade name "Loresta-GP MCP-T610"). The volume resistivity was calculated by multiplying the resistance value by the resistivity correction factor (RCF) 4.532 and the film thickness. The volume resistivity was evaluated according to the following criteria. D indicates non-compliance.

[0241] A: The volume resistivity is less than 7 Ω·cm, and the conductivity is good.

[0242] B: Volume resistivity is above 7 Ω·cm and below 15 Ω·cm, and conductivity is average.

[0243] D: Volume resistivity is above 15 Ω·cm, poor conductivity.

[0244] <Initial Viscosity> A conical viscometer (HAAKE, trade name "Mars2", 35mm diameter, 2° inclined conical plate) was used at a shear rate of 2.0 sec. -1 The viscosity of the obtained composite slurry was measured and evaluated according to the following standards. D indicates non-compliance.

[0245] A: Viscosity is less than 10 Pa·s.

[0246] B: Viscosity is above 10 Pa·s and below 20 Pa·s.

[0247] C: Viscosity above 20 Pa·s and below 50 Pa·s.

[0248] D: Viscosity above 50 Pa·s.

[0249] [Manufacturing of electrode layers for batteries] Application Examples 1C~10C The composite slurry obtained in Examples 1B to 10B was coated onto both sides of a strip of aluminum foil (positive electrode current collector) with an average thickness of 15 μm using a roll coating method to achieve a target weight of 10 mg / cm² (solid composition basis) per side. The coating was then dried (at 180°C for 10 minutes) to form a positive electrode layer. The positive electrode active material layer (positive electrode layer) mounted on this positive electrode current collector was then calendered using a roll press to adjust its properties.

[0250] The resulting electrode layer has a residual solvent content of less than 1%, making it an electrode layer with good finished product properties.

Claims

1. A method for manufacturing a conductive pigment slurry, comprising a pigment dispersing resin (A), a conductive pigment (B), a solvent (C), and a fluororesin (D) optionally included, characterized in that, A process that includes performing the following steps in sequence, Step 1: A step of pulverizing a conductive pigment composition with a pigment concentration of 50% by mass or more of conductive pigment (B) using a pulverizer, and... Step 2: A step of mixing and dispersing the conductive pigment composition obtained in Step 1 with components containing pigment dispersion resin (A), solvent (C), and fluororesin (D) which may be included as needed.

2. The method for manufacturing the conductive pigment paste according to claim 1, characterized in that, The conductive pigment (B) contains carbon nanotubes (B1).

3. The method for manufacturing the conductive pigment paste according to claim 2, characterized in that, Regarding the carbon nanotubes (B1) before and after pulverization in step 1, the following (1) and (2) are satisfied. (1) With 1560cm -1 Above 1600cm -1 The maximum peak intensity is G within the following range, at 1310 cm⁻¹. -1 Above 1350cm -1 The G / D ratio of carbon nanotubes (B1) before pulverization is between 0.1 and 5.0 when the maximum peak intensity D is within the following range. (2) When the G / D ratio of the carbon nanotubes (B1) before pulverization is α and the G / D ratio of the carbon nanotubes (B1) after pulverization is β, β / α < 1.

00.

4. The method for manufacturing the conductive pigment paste according to claim 1, characterized in that, The pigment dispersion resin (A) has at least one alkyl group having 12 or more carbon atoms.

5. The method for manufacturing the conductive pigment paste according to claim 1, characterized in that, The pigment dispersion resin (A) has at least one polar functional group selected from amide, imide, hydroxyl, carboxyl, sulfonic acid, phosphoric acid, silanol, cyano, pyrrolidone and amino groups, and the concentration of the polar functional group of the pigment dispersion resin (A) is 0.3 mmol / g to 23 mmol / g.

6. The method for manufacturing the conductive pigment paste according to claim 1, characterized in that, The conductive pigment paste contains fluoropolymer (D), and the process of mixing the fluoropolymer (D) includes mixing and dissolving it with a solvent preheated to a liquid temperature of 40°C or higher, or includes mixing the fluoropolymer (D) with a solvent and then heating it to a temperature of 40°C or higher.

7. The method for manufacturing the conductive pigment paste according to claim 1, characterized in that, The solvent (C) is N-methyl-2-pyrrolidone.

8. The manufacturing method according to claim 1, characterized in that, Step 2 includes the following steps performed sequentially: Step 2-1: Based on 100% by mass of the total amount of conductive pigment composition in the dispersed conductive pigment slurry, a component containing 70% by mass or less of the conductive pigment composition is added to a disperser for dispersion treatment; and... Step 2-2: The process of adding the conductive pigment composition into a disperser until the desired concentration is reached for dispersion treatment.

9. A method for manufacturing a composite slurry for lithium-ion secondary batteries, characterized in that, The conductive pigment paste obtained by the manufacturing method of any one of claims 1 to 8 further comprises the following steps: Step 3: The process of mixing at least one electrode active material (F).

10. A method for manufacturing an electrode layer for a lithium-ion secondary battery, characterized in that, The process includes coating a composite slurry of a lithium-ion secondary battery obtained by the manufacturing method of claim 9 onto a current collector.

11. A method for manufacturing an electrode for a lithium-ion secondary battery, characterized in that, The process includes coating an electrode insulating portion onto the end or upper layer of the electrode layer obtained by the manufacturing method of the electrode layer for lithium-ion secondary batteries according to claim 10.

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