Dispersed composition

Abstract

This dispersion composition contains a material to be dispersed, a dispersion medium, and a polyamic acid which has at least one type of specific structure selected from a group comprising steroid structures and the structures represented in formula (1). In formula (1), L1 is -O-, -CO-, etc. R1 and R3 are independently a substituted or unsubstituted phenylene group, a substituted or unsubstituted cycloalkylene group, etc. R2 is a single bond, etc. R4 is an alkyl group with 1-18 carbons, etc.　(1) ... -L1-R1-R2-R3-R4

Description

[Technical Field]

[0001] The present invention relates to a dispersion composition and a dispersant. [Background technology]

[0002] Nano-sized materials (i.e., nanoparticles), such as nanocarbons and metal nanoparticles, have excellent electrical, mechanical, and thermal stability properties. Their potential applications and practical applications as nanomaterials in various fields are being explored. These nanoparticles are sometimes dispersed in a medium to utilize their functions, or nanoparticles dispersed in a liquid phase are applied to a substrate to create functional materials. In this case, uniform dispersion of the nanoparticles in the dispersion medium is desirable to fully exploit their properties. Therefore, the use of polyimides as polymeric dispersants has been proposed as a method for suppressing nanoparticle aggregation and improving particle dispersibility (see Non-Patent Document 1). Non-Patent Document 1 discloses the use of polyimides containing sulfonic acid group-containing diamine units as dispersants for carbon nanotubes (CNTs). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] "Overview of Carbon Nanotube Dispersion Technology," Journal of the Society of Rubber Science and Technology of Japan, 2016, Vol. 89, No. 1, pp. 15-21 Summary of the Invention [Problem to be solved by the invention]

[0004] Polyimides having anionic groups on the side chains, such as the polyimide dispersant described in Non-Patent Document 1, do not have sufficiently high solubility in organic solvents. Therefore, when an organic solvent is used as a dispersion medium for dispersing a substance to be dispersed, such as nanocarbon, the dispersant may not dissolve sufficiently in the dispersion medium, and there is a concern that the dispersibility of the substance to be dispersed and the dispersion stability over time may be reduced. Furthermore, when using a dispersion composition such as nanocarbon in devices that form electrodes on a film, it is necessary to remove the dispersant to expose the nanocarbon on the surface. However, when polyimide is used as the dispersant, the dispersant is not sufficiently removable, and there are concerns about the impact on the device due to the inability to remove the dispersant.

[0005] The present invention has been made in consideration of the above-mentioned problems, and its main object is to provide a dispersion composition and a dispersant that are excellent in dispersibility and dispersion stability of the dispersed substance and that are excellent in dispersant removability after film formation. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to solve the above problems and have found that the above problems can be solved by using a polyamic acid having a specific structure. That is, the present invention provides the following means.

[0007] <1> A dispersion composition comprising a substance to be dispersed, a dispersion medium, and a polyamic acid having at least one specific structure selected from the group consisting of a steroid structure and a structure represented by the following formula (1): *-L 1 -R 1 -R 2 -R 3 -R 4 …(1) (In formula (1), L 1 is a single bond, -O-, -CO-, -COO-* 1 , -OCO-* 1 , -NR 5 -, -NR 5 -CO-* 1 , -CO-NR 5 -* 1 , an alkanediyl group having 1 to 6 carbon atoms, -OR 6 -* 1 , or -R 6 -O-* 1 (However, R 5 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, and R 6 is an alkanediyl group having 1 to 3 carbon atoms. 1is R 1 It is a bond with . ) R 1 and R 3 R are each independently a single bond, a substituted or unsubstituted phenylene group, or a substituted or unsubstituted cycloalkylene group. 2 represents a single bond, a substituted or unsubstituted phenylene group, a substituted or unsubstituted cycloalkylene group, or -R 7 -B 1 -R 8 -(However, R 7 and R 8 are each independently a substituted or unsubstituted phenylene group or a substituted or unsubstituted cycloalkylene group, B 1 is a single bond, -O-, -COO-* 2 , -OCO-* 2 , -OCH2-* 2 , -CH2O-* 2 or an alkanediyl group having 1 to 3 carbon atoms. 2 is R 8 It is a bond with . ) R 4 represents a hydrogen atom, a fluorine atom, a cyano group, * 3 -OCO-CH3("* 3 " is R 3 ) is a monovalent group in which at least one hydrogen atom of an alkyl group having 1 to 18 carbon atoms, a fluoroalkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, a fluoroalkoxy group having 1 to 18 carbon atoms, or an alkyl group having 1 to 18 carbon atoms has been substituted with a cyano group. 1 , R 2 and R 3 are all single bonds, or R 1 , R 2 and R 3 When the total number of benzene rings and cycloalkane rings contained in R is 1, R 4 represents an alkyl group having 3 to 18 carbon atoms, a fluoroalkyl group having 3 to 18 carbon atoms, an alkoxy group having 3 to 18 carbon atoms, or a fluoroalkoxy group having 3 to 18 carbon atoms. * represents a bond.) <2> A dispersant containing the polyamic acid. [Effects of the Invention]

[0008] According to the present invention, a dispersion composition having excellent dispersibility and dispersion stability of a dispersed substance and excellent dispersant removal performance after film formation can be obtained. Also, a dispersant having excellent dispersibility and dispersion stability of a dispersed substance and excellent removability after film formation can be obtained. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is an AFM image showing that the dispersant removability was good (A) in the evaluation of an example of the present invention. [Figure 2] 1 is an AFM image showing that the dispersant removability was poor (C) in the evaluation of the comparative example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] The dispersion composition of the present disclosure contains (A) a substance to be dispersed, (B) a dispersion medium, and (C) a polyamic acid. Each component contained in the dispersion composition of the present disclosure, as well as other components that may be optionally blended as needed, will be described below. In this specification, the term "hydrocarbon group" includes chain hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. "Chain hydrocarbon group" refers to a straight-chain hydrocarbon group or a branched hydrocarbon group that does not contain a cyclic structure in the main chain and is composed only of a chain structure. However, it may be saturated or unsaturated. "Alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic hydrocarbon structure as a ring structure and does not contain an aromatic ring structure. However, it does not have to be composed only of an alicyclic hydrocarbon structure and may also contain a chain structure as part of it. "Aromatic hydrocarbon group" refers to a hydrocarbon group that contains an aromatic ring structure as a ring structure. However, it does not have to be composed only of an aromatic ring structure and may contain a chain structure or an alicyclic hydrocarbon structure as part of it.

[0011] <(A) Dispersed entity> The dispersed substance is a substance to be dispersed in a dispersion medium, i.e., a dispersoid. The dispersed substance may be at least one selected from the group consisting of inorganic particles and organic particles, with inorganic particles being preferred. The shape of the dispersed substance is not particularly limited, and examples include spherical, rod-like, fibrous, flat, and disc-like shapes. The primary particle diameter of the dispersed substance is preferably 10 μm or less, more preferably 1 μm or less, and even more preferably 200 nm or less. The primary particle diameter of the dispersed substance is preferably 1 nm or more, more preferably 2 nm or more, and even more preferably 5 nm or more. The "primary particle diameter of the dispersed substance" referred to here is a value determined by measuring the d50 value using a laser diffraction / scattering method.

[0012] Examples of inorganic particles contained in the dispersion composition of the present disclosure include carbon, metal particles, semi-metal particles, silica, inorganic salts, quantum dots, etc. Specific examples of these include carbon, such as carbon black, carbon fiber, carbon nanotubes, graphite, fullerenes, carbon nanohorns, etc.; metal particles, such as simple metals, metal oxides, metal carbides, metal nitrides, etc.; semi-metal particles, such as semi-metal oxides, semi-metal carbides, semi-metal nitrides, etc.; silica, such as wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), colloidal silica, precipitated silica, calcium silicate, aluminum silicate, surface-modified modified silica, etc.; inorganic salts, such as sulfates (calcium sulfate, barium sulfate, etc.), carbonates (calcium carbonate, magnesium carbonate, barium carbonate, etc.), phosphates (calcium phosphate, etc.); quantum dots, such as perovskite quantum dots, carbon-based quantum dots, lead sulfide quantum dots, etc.

[0013] Carbon fibers include carbon nanofibers. Carbon nanotubes include single-walled carbon nanotubes, double-walled carbon nanotubes, and multi-walled carbon nanotubes. Carbon nanotubes may be composed of only carbon, or may have a portion of their structure substituted with other elements or chemically modified, or may be composites with metals (e.g., gold, silver, copper, aluminum, nickel, cobalt, titanium, platinum, etc.).

[0014] In one embodiment of the dispersion composition of the present disclosure, at least one type selected from the group consisting of metal particles and semi-metal particles (hereinafter also referred to as "metal particles, etc.") can be preferably used as the dispersed substance. In another embodiment, at least one type selected from the group consisting of rod-shaped nanostructures and rod-shaped molecules (hereinafter also referred to as "rod-shaped nanostructures, etc.") can be preferably used as the dispersed substance. Examples of rod-shaped molecules include dichroic dyes, and examples of rod-shaped nanostructures include dye aggregates, quantum rods, metal nanorods, carbon nanotubes, proteins, nucleic acids, viruses, etc. When the dispersed substance is at least one type selected from the group consisting of rod-shaped nanostructures and rod-shaped molecules, inorganic particles can be preferably used as the dispersed substance, and carbon nanotubes and metal nanorods can be particularly preferably used.

[0015] Furthermore, the dispersed substance is preferably nanocarbon. Nanocarbon refers to carbon having a primary particle diameter of 1 nm or more and less than 1000 nm. The lower limit of the primary particle diameter of nanocarbon is preferably 2 nm, more preferably 5 nm. On the other hand, the upper limit of the primary particle diameter of nanocarbon is preferably 500 nm, more preferably 200 nm. As the nanocarbon, at least one selected from the group consisting of carbon black, carbon fiber, carbon nanotube, graphite, fullerene, and carbon nanohorn is preferred, with carbon nanotube (CNT) being particularly preferred. Note that as the dispersed substance, one of the above may be used alone, or two or more may be used in combination.

[0016] The content of the dispersed substance in the dispersion composition may be more than 0% by mass, preferably 0.0001% by mass or more, more preferably 0.001% by mass or more, and even more preferably 0.003% by mass or more, relative to the total amount of the dispersion composition. In order to prevent aggregation of the dispersed substance due to an excessive amount of the dispersed substance, the content of the dispersed substance is preferably 0.05% by mass or less, more preferably 0.02% by mass or less, and even more preferably 0.01% by mass or less, relative to the total amount of the dispersion composition.

[0017] <(B) Dispersion medium> The dispersion medium is a phase in which the substance to be dispersed is dispersed, and is preferably an organic solvent. The organic solvent is not particularly limited, and examples thereof include aprotic polar solvents, phenolic solvents, ketone solvents, ether solvents, ester solvents, alcohol solvents, halogenated hydrocarbon solvents, and hydrocarbon solvents.

[0018] Specific examples of these include aprotic polar solvents such as N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,3-dimethyl-1-imidazolidinone, γ-butyrolactone, γ-butyrolactam, N,N-dimethylformamide, N,N-dimethylacetamide, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, N,N,2-trimethylpropanamide, acetonitrile, dimethyl sulfoxide, tetramethylurea, and hexamethylphosphortriamide; Phenolic solvents such as m-cresol, xylenol, and halogenated phenols; Ketone solvents such as cyclobutanone, cyclopentanone, cyclohexanone, cycloheptanone, acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, di-n-butyl ketone, methyl-i-butyl ketone, methyl-n-pentyl ketone, ethyl-n-butyl ketone, methyl-n-hexyl ketone, diisobutyl ketone, and trimethylnonanone; Ether solvents include partial ethers of polyhydric alcohols such as propylene glycol monomethyl ether (PGME), diethylene glycol diethyl ether (DEDG), diethylene glycol ethyl methyl ether, 3-methoxy-1-butanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, ethylene glycol-n-butyl ether (butyl cellosolve), 1-butoxy-2-propanol, ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, and dipropylene glycol monomethyl ether; partial esters of polyhydric alcohols such as diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate (PGMEA), and propylene glycol monoethyl ether acetate; and cyclic ethers such as tetrahydrofuran. Ester solvents such as methyl acetate, ethyl acetate, propyl acetate, n-butyl acetate, i-butyl acetate, sec-butyl acetate, t-butyl acetate, 3-methoxybutyl acetate, methyl acetoacetate, ethyl acetoacetate, ethyl propionate, butyl propionate, methyl lactate, ethyl lactate, butyl lactate, ethylene carbonate, and propylene carbonate; Alcohol solvents such as methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, t-butanol, 1-pentanol, 3-methyl-1-butanol, 1-hexanol, 2-hexanol, heptanol, cyclohexanol, methylcyclohexanol, diacetone alcohol, propane-1,2-diol, and ethylene glycol; Halogenated hydrocarbon solvents such as dichloromethane, 1,2-dichloroethane, 1,4-dichlorobutane, and trichloroethane; Examples of hydrocarbon solvents include hexane, heptane, octane, benzene, toluene, xylene, etc. As the dispersion medium, one type can be used alone, or two or more types can be used in combination.

[0019] Among the above, aprotic polar solvents are preferred because they have high solubility for polyamic acid and can provide excellent dispersibility and dispersion stability for the dispersed material. In particular, at least one compound selected from the group consisting of N-methylpyrrolidone, N-ethylpyrrolidone, and γ-butyrolactone (hereinafter also referred to as "specific solvent") is preferred. The proportion of the aprotic polar solvent in the dispersion medium is preferably more than 50% by mass, more preferably 70% by mass or more, even more preferably 85% by mass or more, and particularly preferably 95% by mass or more, based on the total amount of dispersion medium contained in the dispersion composition. The content of the specific solvent (total amount when two or more types are contained) is preferably 50% by mass or more, more preferably 65% ​​by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more, based on the total amount of dispersion medium contained in the dispersion composition.

[0020] <(C) Polyamic Acid> The dispersion composition of the present disclosure contains a polyamic acid (hereinafter also referred to as polyamic acid [P]). The polyamic acid [P] functions as a dispersant. The polyamic acid [P] has at least one structure (hereinafter also referred to as "specific structure") selected from the group consisting of a steroid structure and a structure represented by the following formula (1): *-L 1 -R 1 -R 2 -R 3 -R 4 …(1) (In formula (1), L 1 is a single bond, -O-, -CO-, -COO-* 1 , -OCO-* 1 , -NR 5 -, -NR 5 -CO-* 1 , -CO-NR 5 -* 1 , an alkanediyl group having 1 to 6 carbon atoms, -OR 6 -* 1 , or -R 6 -O-* 1 (However, R 5is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, and R 6 is an alkanediyl group having 1 to 3 carbon atoms. 1 is R 1 It is a bond with . ) R 1 and R 3 R are each independently a single bond, a substituted or unsubstituted phenylene group, or a substituted or unsubstituted cycloalkylene group. 2 represents a single bond, a substituted or unsubstituted phenylene group, a substituted or unsubstituted cycloalkylene group, or -R 7 -B 1 -R 8 -(However, R 7 and R 8 are each independently a substituted or unsubstituted phenylene group or a substituted or unsubstituted cycloalkylene group, B 1 is a single bond, -O-, -COO-* 2 , -OCO-* 2 , -OCH2-* 2 , -CH2O-* 2 or an alkanediyl group having 1 to 3 carbon atoms. 2 is R 8 It is a bond with . ) R 4 represents a hydrogen atom, a fluorine atom, a cyano group, * 3 -OCO-CH3(* 3 is R 3 is a bond to the alkyl group having 1 to 18 carbon atoms, a fluoroalkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, a fluoroalkoxy group having 1 to 18 carbon atoms, or a monovalent group in which at least one hydrogen atom of an alkyl group having 1 to 18 carbon atoms is substituted with a cyano group. 1 , R 2 and R 3 are all single bonds, or R 1 , R 2 and R 3 When the total number of benzene rings and cycloalkane rings contained in R is 1, R 4represents an alkyl group having 3 to 18 carbon atoms, a fluoroalkyl group having 3 to 18 carbon atoms, an alkoxy group having 3 to 18 carbon atoms, or a fluoroalkoxy group having 3 to 18 carbon atoms. * represents a bond.)

[0021] A steroid structure generally has a sterane (i.e., cyclopentanoperhydrophenanthrene) skeleton and a substituent such as an alkyl group attached thereto. When the specific structure is a steroid structure, preferred examples thereof include a cholestane skeleton, a cholestene skeleton, and a lanostane skeleton. A steroid structure has a linking group (e.g., L in the above formula (1)) attached to the skeleton. 1 In the steroid structure, it is preferable that the portion other than the linking group is a structure consisting only of hydrogen atoms and carbon atoms (i.e., a hydrocarbon group).

[0022] When the specific structure is a structure represented by the above formula (1), in the substituted phenylene group and substituted cycloalkylene group in the above formula (1), the substituent bonded to the ring is preferably an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorine atom, or a cyano group. The number of substituents each of the substituted phenylene group and the substituted cycloalkylene group is preferably 1 or 2, more preferably 1. Furthermore, the substituted or unsubstituted phenylene group and the substituted or unsubstituted cycloalkylene group in the formula (1) may preferably be an unsubstituted phenylene group and an unsubstituted cycloalkylene group. The cycloalkylene group is a cycloalkanediyl group. The cycloalkylene group in the formula (1) is preferably a cyclohexylene group (i.e., a cyclohexanediyl group), more preferably a cyclohexane-1,4-diyl group. The phenylene group (i.e., a benzenediyl group) in the formula (1) is preferably a benzene-1,4-diyl group.

[0023] R 4is a monovalent group in which at least one hydrogen atom of an alkyl group having 1 to 18 carbon atoms, a fluoroalkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, a fluoroalkoxy group having 1 to 18 carbon atoms, or an alkyl group having 1 to 18 carbon atoms is substituted with a cyano group, R 4 is preferably linear. The number of carbon atoms is preferably 2 or more, more preferably 3 or more, and even more preferably 5 or more.

[0024] R 1 , R 2 and R 3 are all single bonds, or R 1 , R 2 and R 3 When the total number of benzene rings and cycloalkane rings contained in R is 1, the dispersibility and dispersion stability of the dispersed substance can be improved. 4 Preferably, the number of carbon atoms is 4 or more, more preferably 7 or more, and even more preferably 10 or more.

[0025] The structure represented by the above formula (1) preferably has a ring structure from the viewpoint of further improving the dispersibility and dispersion stability of the dispersed substance. 1 , R 2 and R 3 The total number of benzene rings and cycloalkane rings contained in -R in formula (1) is preferably 1 or more, more preferably 1 to 4, and even more preferably 2 to 4. 1 -R 2 -R 3 -R 4 is preferably a hydrocarbon group in some cases.

[0026] From the viewpoint of further increasing the dispersibility and dispersion stability of the dispersed substance, the polyamic acid [P] has the specific structure represented by R 1 , R 2 and R 3It is preferable that the compound has at least one selected from the group consisting of a structure in which the total number of benzene rings and cycloalkane rings is two or more and a steroid structure, and it is particularly preferable that the compound has at least a steroid structure.

[0027] In the polyamic acid [P], the specific structure is preferably bonded to an aromatic ring such as a benzene ring. The number of carbon atoms in the specific structure is, for example, 3 to 50, preferably 5 to 40, more preferably 8 to 36, and even more preferably 12 or more, 16 or more, or 20 or more. In addition, the specific structure may preferably be composed of only carbon atoms, hydrogen atoms, and oxygen atoms, or may preferably be composed of only carbon atoms and hydrogen atoms. The specific structure may be bonded to a linking group containing an oxygen atom (for example, the above L 1 In some cases, it may be preferable that the alkyl group is composed of a single bond represented by the following formula (a group other than an alkanediyl group and a single bond represented by the following formula) and a hydrocarbon group.

[0028] The polyamic acid [P] has an amic acid structure in the molecule. The method for synthesizing the polyamic acid [P] is not particularly limited. For example, the polyamic acid [P] can be synthesized by reacting a tetracarboxylic dianhydride with a diamine compound, and using a diamine compound having a specific structure such as a steroid structure.

[0029] (Synthesis of polyamic acid [P]) Tetracarboxylic acid dianhydride The tetracarboxylic acid dianhydride used in the synthesis of the polyamic acid [P] is not particularly limited, but examples thereof include aliphatic tetracarboxylic acid dianhydrides, alicyclic tetracarboxylic acid dianhydrides, and aromatic tetracarboxylic acid dianhydrides.

[0030] Specific examples of the tetracarboxylic dianhydride include aliphatic tetracarboxylic dianhydrides such as butanetetracarboxylic dianhydride and ethylenediaminetetraacetic dianhydride; Alicyclic tetracarboxylic dianhydrides include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic dianhydride, 5-(2,5-dioxotetrahydrofuran-3-yl)-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, 5-(2,5-dioxotetrahydrofuran-3-yl)-8-methyl-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, 3-oxabicyclo[3.2 .1]octane-2,4-dione-6-spiro-3'-(tetrahydrofuran-2',5'-dione), 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 3,5,6-tricarboxy-2-carboxymethylnorbornane-2:3,5:6-dianhydride, bicyclo[3.3.0]octane-2,4,6,8-tetracarboxylic acid 2:4,6:8-dianhydride, bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic acid 2:3,5:6-dianhydride, 4,9-dioxatricyclo[5.3.1.0]octane-2,4,6,8-tetracarboxylic acid 2:4,6:8-dianhydride, bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic acid 2:3,5:6-dianhydride 2,6 ]undecane-3,5,8,10-tetraone, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, etc.; Aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride, 4,4'-biphthalic dianhydride, 4,4'-carbonyldiphthalic dianhydride, 4,4'-oxydiphthalic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, naphthalene-1,4,5,6-tetracarboxylic dianhydride, ethylene glycol bis(anhydrotrimellitate), 1,3-propylene glycol bis(anhydrotrimellitate), and the like; In addition, as the tetracarboxylic dianhydride, the tetracarboxylic dianhydrides described in JP-A-2010-97188 can be used.

[0031] The tetracarboxylic acid dianhydride used in the synthesis of the polyamic acid [P] preferably contains an alicyclic tetracarboxylic acid dianhydride, since this improves the solubility of the polyamic acid [P] in the dispersion medium and enhances the dispersibility and dispersion stability of the dispersed material. In the synthesis of the polyamic acid [P], the proportion of the alicyclic tetracarboxylic acid dianhydride relative to the total amount of tetracarboxylic acid dianhydrides used (i.e., the proportion of structural units derived from alicyclic tetracarboxylic acid dianhydrides (also referred to as "structural units UA") relative to the total amount of structural units derived from tetracarboxylic acid dianhydrides constituting the polyamic acid [P]) may be, for example, 1 mol% or more, but is preferably 5 mol% or more, more preferably 15 mol% or more, even more preferably 25 mol% or more, and particularly preferably 50 mol% or more. This proportion may be 100 mol% or less, or may be 99 mol% or less.

[0032] The alicyclic tetracarboxylic dianhydride used in the synthesis of the polyamic acid [P] is preferably at least one selected from the group consisting of 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic dianhydride, bicyclo[3.3.0]octane-2,4,6,8-tetracarboxylic 2:4,6:8-dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, and 1,2,3,4-cyclopentanetetracarboxylic dianhydride. The tetracarboxylic dianhydrides may be used singly or in combination of two or more.

[0033] Diamine compounds The diamine compound used to synthesize the polyamic acid [P] preferably contains a diamine having the above-mentioned specific structure (hereinafter also referred to as "specific diamine"). The polymerization method using the specific diamine is preferable in that it is easy to synthesize the polyamic acid having the above-mentioned specific structure and it is easy to adjust the content ratio of the above-mentioned specific structure in one molecule of the polyamic acid. By polymerizing a monomer containing the specific diamine, a partially imidized product having a structural unit derived from the specific diamine (hereinafter also referred to as "structural unit UD") can be obtained as the polyamic acid [P].

[0034] The specific diamine may be any of an aliphatic diamine, an alicyclic diamine, and an aromatic diamine as long as it has the above-mentioned specific structure. From the viewpoint of further improving the dispersibility and dispersion stability of the dispersed substance, the specific diamine is preferably an aromatic diamine, and more preferably at least one selected from the group consisting of compounds represented by the following formula (2) and compounds represented by the following formula (3):

[0035] [ka] (In formula (2), L 2 is a single bond, -O-, -CO-, -COO-* 4 , -OCO-* 4 , -NR 10 -, -NR 10 -CO-* 4 , or -CO-NR 10 -* 4 (However, R 10 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. 4 is R 9 It is a bond with . ) R 9 is a monovalent group having a steroid skeleton.

[0036] [ka] (In formula (3), L 1 , R 1 , R 2 , R 3 and R4 is the same as the above formula (1).

[0037] In the above formula (2), "-L 2 -R 9 " and "-L" in the above formula (3) 1 -R 1 -R 2 -R 3 -R 4 " is the specific structure.

[0038] Specific examples of the specific diamine include compounds represented by the above formula (2), such as cholestanyloxy-3,5-diaminobenzene, cholesteryloxy-3,5-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholesteryloxy-2,4-diaminobenzene, cholestanyl 3,5-diaminobenzoate, cholesteryl 3,5-diaminobenzoate, lanostannyl 3,5-diaminobenzoate, 3,6-bis(4-aminobenzoyloxy)cholestane, 3,6-bis(4-aminophenoxy)cholestane, etc.; Examples of the compound represented by the above formula (3) include butanoxy-2,4-diaminobenzene, butanoxy-3,5-diaminobenzene, pentanoxy-2,4-diaminobenzene, pentanoxy-3,5-diaminobenzene, hexanoxy-3,5-diaminobenzene, heptanoxy-2,4-diaminobenzene, dodecanoxy-2,4-diaminobenzene, pentadecanoxy-2,4-diaminobenzene, hexadecanoxy-2,4-diaminobenzene, octadecanoxy-2,4-diaminobenzene, pentadecanoxy-2,5-diaminobenzene, octadecanoxy-2,5-diaminobenzene, 4-(4'-trifluoromethoxybenzoyloxy)cyclohexyl-3,5-diaminobenzoate, and compounds represented by the following formula (E-1):

[0039] [ka] (In formula (E-1), X I and X IIare each independently a single bond, -O-, *-COO- or *-OCO- (where * represents X I ) and R I is an alkanediyl group having 1 to 3 carbon atoms, and R II is a single bond or an alkanediyl group having 1 to 3 carbon atoms, and R 11 represents a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, a fluoroalkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, or a fluoroalkoxy group having 1 to 18 carbon atoms. a represents an integer of 0 to 2, b represents an integer of 0 to 2, and d represents 0 or 1, provided that a and b are not 0 at the same time.

[0040] Specific examples of the compound represented by the above formula (E-1) include compounds represented by the following formulas (E-1-1) to (E-1-13).

[0041] [ka]

[0042] [ka]

[0043] (In formulas (E-1-1) to (E-1-13), X 1 is -O-, -OCH2-, -CH2O-, -COO-CH2- or -CH2-OCO-, and R 11 has the same meaning as in formula (E-1) above. 12 is an alkyl group having 3 to 18 carbon atoms, a fluoroalkyl group having 3 to 18 carbon atoms, an alkoxy group having 3 to 18 carbon atoms, or a fluoroalkoxy group having 3 to 18 carbon atoms.

[0044] In the polyamic acid [P], the content of the structural unit UD derived from the specific diamine is preferably 1 mol% or more relative to the total amount of structural units derived from the diamine constituting the polyamic acid [P]. A content of the structural unit UD of 1 mol% or more is preferable because the introduction of the specific structure can sufficiently improve the dispersibility and dispersion stability of the dispersed substance. From this perspective, the content of the structural unit UD is more preferably 2 mol% or more, even more preferably 5 mol% or more, and even more preferably 10 mol% or more, 15 mol% or more, or 20 mol% or more relative to the total amount of structural units derived from the diamine constituting the polyamic acid [P]. Furthermore, from the viewpoint of suppressing a decrease in the solubility of the polyamic acid [P] in the dispersion medium, the content of the structural unit UD is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 80 mol% or less relative to the total amount of structural units derived from the diamine constituting the polyamic acid [P]. In the synthesis of the polyamic acid [P], the specific diamine may be used alone or in combination of two or more.

[0045] In synthesizing the polyamic acid [P], only the specific diamine may be used as the diamine compound, or a diamine not having the specific structure (hereinafter also referred to as "other diamine") may be used together with the specific diamine. As the other diamine, a diamine having neither an anionic functional group nor a cationic functional group is preferred from the viewpoint of not impairing the solubility of the polyamic acid [P] in an organic solvent. Furthermore, from the viewpoint of further improving the dispersibility and dispersion stability of the dispersed substance, the other diamine is preferably an aromatic diamine.

[0046] Specific examples of other diamines include aliphatic diamines such as metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, and 1,3-bis(aminomethyl)cyclohexane; Alicyclic diamines, such as 1,4-diaminocyclohexane and 4,4'-methylenebis(cyclohexylamine); Examples of aromatic diamines include paraphenylenediamine, metaphenylenediamine, 4,4'-diaminodiphenylmethane, 4-aminophenyl-4'-aminobenzoate, 4,4'-diaminobenzanilide, 4,4'-diaminodiphenylamine, 4,4'-diaminoazobenzene, 1,5-bis(4-aminophenoxy)pentane, 1,7-bis(4-aminophenoxy)heptane, bis[2-(4-aminophenyl)ethyl]hexanedioic acid, N,N-bis(4-aminophenyl)methylamine, 1,5-diaminonaphthalene, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 2,7-diaminofluorene, 4,4'-diamino main-chain diamines such as diphenyl ether, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-(p-phenylenediisopropylidene)bisaniline, 4,4'-(m-phenylenediisopropylidene)bisaniline, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-[4,4'-propane-1,3-diylbis(piperidine-1,4-diyl)]dianiline, 1,4-bis(4-aminophenyl)piperazine, and 1,4-bis(4-amino(3-pyridinyl))piperazine; Examples of diaminoorganosiloxanes include 1,3-bis(3-aminopropyl)-tetramethyldisiloxane, etc. In addition, diamines described in JP-A-2010-97188 can also be used.

[0047] In the polyamic acid [P], the content of structural units derived from other diamines (hereinafter also referred to as "structural units UE") is preferably 99 mol% or less, more preferably 98 mol% or less, and even more preferably 95 mol% or less, based on the total amount of structural units derived from diamines constituting the polyamic acid. Furthermore, the content of structural units UE is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 20 mol% or more, based on the total amount of structural units derived from diamines constituting the polyamic acid. When synthesizing the polyamic acid, one type of other diamine may be used alone, or two or more types may be used in combination.

[0048] The polyamic acid [P] may be a copolymer essentially consisting of a tetracarboxylic dianhydride and a diamine compound. In the polyamic acid [P], the molar ratio of the structural units derived from the tetracarboxylic dianhydride to the structural units derived from the diamine compound is preferably in the range of 40:60 to 60:40, more preferably 45:55 to 55:45. The total content of the structural units derived from the tetracarboxylic dianhydride and the structural units derived from the diamine compound relative to the total structural units contained in the polyamic acid [P] is preferably 70 mol% or more, more preferably 80 mol% or more, 90 mol% or more, or 95 mol% or more.

[0049] The polyamic acid [P] can be obtained by reacting the above-mentioned tetracarboxylic dianhydride with a diamine compound, optionally together with a molecular weight modifier. The ratio of the tetracarboxylic dianhydride and the diamine compound used in the synthesis reaction of the polyamic acid [P] is preferably such that 0.2 to 2 equivalents of the acid anhydride group of the tetracarboxylic dianhydride are used relative to 1 equivalent of the amino group of the diamine compound, more preferably 0.3 to 1.4 equivalents, even more preferably 0.6 to 1.2 equivalents, and even more preferably 0.8 to 1.1 equivalents.

[0050] Examples of molecular weight modifiers include acid monoanhydrides such as maleic anhydride, phthalic anhydride, and itaconic anhydride, monoamine compounds such as aniline, cyclohexylamine, and n-butylamine, and monoisocyanate compounds such as phenyl isocyanate and naphthyl isocyanate. The proportion of the molecular weight modifier used is preferably 20 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of the total of the tetracarboxylic dianhydride and diamine compounds used.

[0051] The synthesis reaction of the polyamic acid [P] is preferably carried out in an organic solvent. The reaction temperature is preferably −20° C. to 150° C., more preferably 0 to 100° C. The reaction time is preferably 0.1 to 24 hours, more preferably 0.5 to 12 hours.

[0052] Examples of organic solvents used in the reaction include aprotic polar solvents, phenolic solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, and hydrocarbons. Among these organic solvents, it is preferable to use one or more selected from the group consisting of aprotic polar solvents and phenolic solvents (Group 1 organic solvents), or a mixture of one or more selected from Group 1 organic solvents with one or more selected from the group consisting of alcohols, ketones, esters, ethers, halogenated hydrocarbons, and hydrocarbons (Group 2 organic solvents). In the latter case, the proportion of the Group 2 organic solvent used is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less, based on the total amount of the Group 1 organic solvents and the Group 2 organic solvents.

[0053] Particularly preferred organic solvents are one or more selected from the group consisting of N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide, m-cresol, xylenol, and halogenated phenols. It is preferable to use one or more of these as the solvent, or a mixture of one or more of these with other organic solvents in the above-mentioned proportions. The amount (a) of the organic solvent used is preferably an amount such that the total amount (b) of the tetracarboxylic dianhydride and the diamine is 0.1 to 50% by mass relative to the total amount (a+b) of the reaction solution.

[0054] The polyamic acid [P] obtained as described above preferably has a solution viscosity of 10 to 2000 mPa·s, and more preferably 20 to 1000 mPa·s, when made into a 10% by mass solution. The solution viscosity (mPa·s) of the polyamic acid is a value measured at 25°C using an E-type rotational viscometer for a 10% by mass solution prepared using a good solvent for the polyamic acid (e.g., N-methyl-2-pyrrolidone or γ-butyrolactone).

[0055] The polyamic acid [P] has a weight average molecular weight (Mw) in terms of polystyrene measured by gel permeation chromatography (GPC) of preferably 1,000 to 500,000, more preferably 2,000 to 300,000. The molecular weight distribution (Mw / Mn), which is expressed as the ratio of Mw to the number average molecular weight (Mn) in terms of polystyrene measured by GPC, is preferably 15 or less, more preferably 10 or less.

[0056] Here, carbon nanotubes, which are one of the dispersed substances, have excellent properties such as electrical conductivity, heat resistance, toughness, and light weight. However, carbon nanotubes have a high tendency to aggregate, making them difficult to uniformly disperse in a dispersion medium. Furthermore, if the carbon nanotubes are not dispersed well, there is a concern that the various properties of the carbon nanotubes (e.g., electrical conductivity, resistance to external forces) may not be fully exhibited in films, wiring, etc. obtained using the dispersion composition. In this regard, the dispersion composition of the present disclosure contains polyamic acid [P], thereby providing excellent dispersibility of carbon nanotubes in dispersion media (e.g., organic solvents). Furthermore, by using a dispersion composition containing carbon nanotubes and polyamic acid [P], it is possible to form films, etc. that are excellent in dispersant removal properties and electrical properties.

[0057] The content of the polyamic acid [P] in the dispersion composition is appropriately selected taking into consideration the type of material to be dispersed, but is preferably 5,000 parts by mass or more, more preferably 10,000 parts by mass or more, relative to 100 parts by mass of the material to be dispersed. The content of the polyamic acid [P] is preferably 100,000 parts by mass or less, more preferably 50,000 parts by mass or less, and even more preferably 20,000 parts by mass or less, relative to 100 parts by mass of the material to be dispersed.

[0058] More specifically, for example, when the dispersed substance is carbon nanotubes, from the viewpoint of sufficiently increasing the dispersibility of the carbon nanotubes, the content of the polyamic acid [P] is preferably 5,000 parts by mass or more, more preferably 10,000 parts by mass or more, relative to 100 parts by mass of the carbon nanotubes, and the content of the polyamic acid [P] is preferably 100,000 parts by mass or less, more preferably 50,000 parts by mass or less, and even more preferably 20,000 parts by mass or less, relative to 100 parts by mass of the carbon nanotubes.

[0059] Although it is not clear why the dispersibility and dispersion stability of the dispersed substance can be improved by incorporating polyamic acid [P] into the dispersion composition, one hypothesis is that the aggregation of the dispersed substance is suppressed due to the excluded volume effect of the specific structure of polyamic acid [P], and that the dispersion stability of the dispersed substance is improved due to the electrostatic interaction of polyamic acid.

[0060] <Other ingredients> The dispersion composition of the present disclosure may contain other components in addition to the dispersed substance, dispersion medium, and polyamic acid [P], as long as the purpose and effects of the present disclosure are not impaired. Examples of other components include dispersants other than the polyamic acid [P] (hereinafter also referred to as "other dispersants"), surfactants, fillers, antifoaming agents, sensitizers, antioxidants, adhesion aids, antistatic agents, leveling agents, antibacterial agents, etc. The content ratio of other components can be appropriately set depending on each compound to be blended, as long as the effects of the present disclosure are not impaired.

[0061] In addition, when the dispersion composition of the present disclosure contains other dispersants, the content of the other dispersants is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 1% by mass or less, based on the total amount of the polyamic acid [P] and other dispersants contained in the dispersion composition.

[0062] The method for preparing the dispersion composition is not particularly limited, and can be carried out according to a known method. For example, the dispersion composition can be prepared by mixing the substance to be dispersed, the dispersion medium, and the dispersant, and optionally heating, stirring, etc. The temperature when preparing the dispersion composition is preferably 5 to 90°C, more preferably 10 to 65°C. The treatment of mixing the substance to be dispersed, the dispersion medium, and the dispersant may be carried out using a homogenizer, a bead mill, etc.

[0063] The solids concentration of the dispersion composition (i.e., the proportion of the total mass of the components of the dispersion composition other than the dispersion medium to the total mass of the dispersion composition) is appropriately selected taking into consideration the viscosity, volatility of the dispersion medium, etc. For example, when the dispersed substance is carbon such as carbon nanotubes, the solids concentration is preferably in the range of 0.1 to 10.0 mass%, more preferably in the range of 0.3 to 6.0 mass%, and even more preferably in the range of 0.5 to 2.0 mass%.

[0064] The dispersion composition of the present disclosure uses a polyamic acid [P] as a polymer dispersant. This suppresses aggregation of the dispersed substance in the dispersion medium, allowing the dispersed substance to be uniformly dispersed. The dispersion composition of the present disclosure is applied to a substrate, and then preferably heated to remove the dispersion medium, thereby forming a thin film containing the dispersed substance on the substrate. The dispersion composition of the present disclosure can also be used in liquid form, either as is or by mixing with other dispersions.

[0065] The dispersion composition and dispersant of the present disclosure can be used for various applications depending on the type of dispersed substance, specifically, for transparent conductive films, antistatic films, insulating films, protective films, antireflective films, colored films, field effect transistors (FETs), touch panels, conductive inks, paints, printing inks, inkjet coating inks, etc. [Example]

[0066] The present invention will be explained in more detail below with reference to examples, but is not limited to these examples. In the following examples, the weight-average molecular weight Mw of the polymer and the solution viscosity of the polymer solution were measured by the following methods. The required amounts of the raw material compounds and polymers used in the following examples were secured by repeating synthesis on a synthesis scale shown in the following synthesis examples as necessary.

[0067] 1. Polymer synthesis [Synthesis Example 1: Synthesis of polyamic acid] 33.4 g (95 mol parts) of 2,3,5-tricarboxycyclopentylacetic dianhydride (AN-2), 16.4 g (20 mol parts) of cholestanyl 3,5-diaminobenzoate (DA-1), and 25.1 g (80 mol parts) of 4,4'-diaminodiphenyl ether (DA-6) were dissolved in 425 g of N-methyl-2-pyrrolidone (NMP) and reacted at room temperature for 6 hours. The reaction mixture was poured into a large excess of methanol to precipitate the reaction product. The precipitate was washed with methanol and dried under reduced pressure at 40°C for 15 hours to obtain 67 g of polyamic acid (hereinafter referred to as "polymer (paa-1)").

[0068] [Synthesis Examples 2 to 10, Comparative Synthesis Examples 1 to 2] Polyamic acids (polymers (paa-2) to (paa-12)) were obtained in the same manner as in Synthesis Example 1, except that the types and amounts of tetracarboxylic dianhydrides and diamine compounds used in the reaction were changed as shown in Table 1 below. Note that (paa-11) and (paa-12) obtained in Comparative Synthesis Example 1 and Comparative Synthesis Example 2 are polyamic acids that do not have a steroid structure or a structure represented by formula (1). Each polyamic acid is shown in Table 1 below.

[0069] Comparative Example 3: Synthesis of Polyimide As in Synthesis Example 1, 95 mol parts of 2,3,5-tricarboxycyclopentylacetic dianhydride (AN-2), 20 mol parts of cholestanyl 3,5-diaminobenzoate (DA-1), and 80 mol parts of 4,4'-diaminodiphenyl ether (DA-6) were dissolved in N-methyl-2-pyrrolidone (NMP) to obtain a polyamic acid solution with a polymer concentration of 15% by mass. NMP was added to the resulting polyamic acid solution to dilute it to a polymer concentration of 10% by mass, after which a predetermined amount of pyridine and acetic anhydride were added and the mixture was reacted at 110°C for 4 hours. The resulting reaction mixture was then poured into a large excess of methanol to precipitate the reaction product. The recovered precipitate was washed with methanol and then dried under reduced pressure at 100°C to obtain a polyimide (hereinafter referred to as "polymer (PI-1)"). The imidization rate of the resulting polymer (PI-1) was 50%.

[0070] [Table 1]

[0071] The numerical values ​​in Table 1 indicate the proportion (mol %) of tetracarboxylic dianhydrides used relative to the total amount of tetracarboxylic dianhydrides used in the reaction, and the numerical values ​​in Table 1 indicate the proportion (mol %) of diamine compounds used relative to the total amount of diamine compounds used in the reaction. The molar ratio of all tetracarboxylic dianhydrides to all diamine compounds used in each Synthesis Example and Comparative Example was 95:100. The abbreviations for the tetracarboxylic dianhydrides and diamine compounds in Table 1 are as follows: (Tetracarboxylic acid dianhydride) AN-1; Bicyclo[3.3.0]octane-2,4,6,8-tetracarboxylic acid 2:4,6:8-dianhydride AN-2; 2,3,5-tricarboxycyclopentylacetic dianhydride AN-3; Pyromellitic dianhydride (Diamine compounds) DA-1; cholestanyl 3,5-diaminobenzoate DA-2; Cholestanyloxy-2,4-diaminobenzene DA-3: A compound represented by the following formula (DA-3): DA-4: A compound represented by the following formula (DA-4): DA-5; Paraphenylenediamine DA-6; 4,4'-diaminodiphenyl ether DA-7: A compound represented by the following formula (DA-7): DA-8: A compound represented by the following formula (DA-8):

[0072] [ka]

[0073] 2. Preparation and Evaluation of Dispersion Compositions [Example 1] (1) Preparation of Dispersion Composition NMP was added as a dispersion medium to a vessel containing 10 parts by mass of single-walled carbon nanotubes (SWNTs) as a dispersion medium and 500 parts by mass of the polymer (paa-1) obtained in Synthesis Example 1 as a dispersant, making the total amount 100,000 parts by mass. Next, ultrasonic dispersion was carried out for 60 minutes to prepare a dispersion composition (S-1).

[0074] (2) Evaluation of dispersibility The dispersion composition (S-1) obtained in (1) above was left to stand on a flat surface in an environment of 25°C. The evaluation was made as follows: if the dispersed CNTs maintained their initial dispersion state without settling after one week, the dispersion composition (S-1) was evaluated as "best quality (A)." ++ If the CNTs do not settle and maintain their initial dispersion state for three days, the result is rated as "Excellent (A + If the CNTs did not settle and maintained their initial dispersed state for one day, the rating was "good (A)." If the CNTs did not settle and maintained their initial dispersed state for three hours, the rating was "fair (B)." If CNTs settled or aggregated within three hours, the rating was "poor (C)." As a result, the dispersibility of this dispersion composition (S-1) was rated as "best (A)." ++ )"

[0075] (3) Evaluation of dispersion stability (durability) A dispersion composition was prepared in the same manner as in (1) above. The obtained dispersion composition was left standing on a flat surface in an environment of 40°C, and the dispersion state was observed over time. The evaluation was made as "best quality (A)" if the CNTs did not settle after one week and the initial dispersion state was maintained. ++ If the CNTs do not settle and maintain their initial dispersion state within three days, the result is rated as "Excellent (A + If the CNTs did not settle and maintained their initial dispersed state within one day, the rating was "good (A)." If the CNTs did not settle and maintained their initial dispersed state within three hours, the rating was "fair (B)." If settling or aggregation was observed within three hours, the rating was "poor (C)." As a result, the dispersion stability of this dispersion composition (S-1) was rated as "best (A)." ++ )"

[0076] (4) Evaluation of application properties The dispersion composition (S-1) obtained in (1) above was applied to a glass substrate using a blade and dried on a hot plate at 80°C for 10 minutes to form a coating film with a thickness of 0.1 μm at the center of the substrate. This coating film was observed under a microscope at 50x magnification to check for thickness unevenness and the presence of pinholes. The coating was evaluated as "good (A)" when neither thickness unevenness nor pinholes were observed, "fair (B)" when at least one of thickness unevenness and pinholes was slightly observed, and "poor (C)" when at least one of thickness unevenness and pinholes was clearly observed. As a result, neither thickness unevenness nor pinholes were observed, and the coating property of this dispersion composition (S-1) was evaluated as "good (A)."

[0077] (5) Evaluation of dispersant removal The dispersion composition (S-1) obtained in (1) above was applied to a glass substrate using a blade and dried on a hot plate at 80 °C for 10 minutes, forming a coating with a thickness of 0.1 μm at the center of the substrate. This coating was then immersed in a sodium hydroxide solution for 1 minute, and the surface was observed using an atomic force microscope (AFM, Hitachi High-Tech Corporation). A sample in which the surface dispersant was removed and the CNTs were exposed was rated "Good (A)" (e.g., Figure 1). A sample in which the CNTs were partially exposed was rated "Fair (B)." A sample in which the surface was covered with resin and no exposed CNTs were visible, or in which the film formation was so poor that it was impossible to distinguish, was rated "Poor (C)" (e.g., Figure 2). As a result, the dispersant was removed from the surface, revealing the CNTs, and the dispersant removability of this dispersion composition (S-1) was rated "Good (A)."

[0078] [Examples 2 to 18, Comparative Examples 1 to 3] Dispersion compositions (S-2) to (S-18) and (sr-1) to (sr-3) were prepared in the same manner as dispersion composition (S-1) in Example 1, except that the compositions (types and amounts) of the dispersed substance and dispersant in the dispersion compositions were changed as shown in Table 2 below. In addition, various evaluations were performed in the same manner as in Example 1, except that dispersion compositions (S-2) to (S-18) and (sr-1) to (sr-3), respectively, were used instead of dispersion composition (S-1). The evaluation results of Examples 1 to 18 and Comparative Examples 1 to 3 are summarized in Table 2 below.

[0079] [Table 2]

[0080] In Table 2, the numerical values ​​for "amount blended" indicate parts by mass. The abbreviations for the dispersed substances are as follows: <Dispersed entity> SWNT; Single-wall carbon nanotube

[0081] From the results in Table 2, compared to the case of using polyimide as the dispersant in Comparative Example 3 and the cases of using polyamic acid without a specific structure in Comparative Examples 1 and 2, Examples 1 to 18 were rated as excellent, excellent, good or fair in terms of dispersibility, dispersion stability, coatability and dispersant removability. By using a dispersion composition with good dispersibility, dispersion stability, and dispersant removal properties, it was possible to obtain a film with good coating properties on a substrate and with carbon nanotubes exposed on the surface effectively.

Claims

1. A dispersed material; A dispersion medium; a polyamic acid having at least one specific structure selected from the group consisting of a steroid structure and a structure represented by the following formula (1); Contains the dispersed material is inorganic particles, the dispersion medium comprises an aprotic polar solvent, the proportion of the aprotic polar solvent is 70% by mass or more based on the total amount of the dispersion medium; the polyamic acid has structural units UD derived from a diamine compound having the specific structure, The dispersion composition, wherein the diamine compound is at least one selected from the group consisting of compounds represented by the following formula (2) and compounds represented by the following formula (3): *-L １ -R １ -R ２ -R ３ -R ４ …(1) (In formula (1), L １ represents a single bond, -O-, -CO-, -COO-* １ , -OCO-* １ , -NR ５ -, -NR ５ -CO-* １ , —CO—NR ５ -* １ , an alkanediyl group having 1 to 6 carbon atoms, —O—R ６ -* １ , or -R ６ -O-* １ (However, R ５ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, and R ６ is an alkanediyl group having 1 to 3 carbon atoms. １ is R １ It is a bond with . ) R １ and R ３ are each independently a single bond, a substituted or unsubstituted phenylene group, or a substituted or unsubstituted cycloalkylene group. ２ represents a single bond, a substituted or unsubstituted phenylene group, a substituted or unsubstituted cycloalkylene group, or -R ７ -B １ -R ８ - (However, R ７ and R ８ are each independently a substituted or unsubstituted phenylene group or a substituted or unsubstituted cycloalkylene group, B １ represents a single bond, -O-, -COO-* ２ , -OCO-* ２ , -OCH ２ -* ２ , -CH ２ O-* ２ or an alkanediyl group having 1 to 3 carbon atoms. ２ is R ８ It is a bond with . ) R ４ represents a hydrogen atom, a fluorine atom, a cyano group, * ３ -OCO-CH ３ (* ３ is R ３ is a bond to the alkyl group having 1 to 18 carbon atoms, a fluoroalkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, a fluoroalkoxy group having 1 to 18 carbon atoms, or a monovalent group in which at least one hydrogen atom of an alkyl group having 1 to 18 carbon atoms is substituted with a cyano group. １ , R ２ and R ３ are all single bonds, or R １ , R ２ and R ３ When the total number of benzene rings and cycloalkane rings contained in R is 1, R ４ is an alkyl group having 3 to 18 carbon atoms, a fluoroalkyl group having 3 to 18 carbon atoms, an alkoxy group having 3 to 18 carbon atoms, or a fluoroalkoxy group having 3 to 18 carbon atoms. * is a bond. 【Chemistry 1】 In formula (2), L 2 is a single bond, —O—, —CO—, —COO-* 4 , —OCO-* 4 , —NR 10 —, —NR 10 -CO-* 4 , or —CO—NR 10 -* 4 (wherein R 10 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, and * 4 is a bond to R 9 ). R 9 is a monovalent group having a steroid skeleton. The two amino groups are bonded to each other at the meta position.) 【Chemistry 2】 (In formula (3), L 1 , R 1 , R 2 , R 3 and R 4 have the same meanings as in formula (1). The two amino groups are bonded to each other at the meta position.)

2. A dispersion composition as described in claim 1, wherein the content ratio of the structural unit UD to the total amount of structural units derived from diamines constituting the polyamic acid is 1 mol% or more and 95 mol% or less.

3. 3. The dispersion composition according to claim 1, wherein the polyamic acid has a structural unit UA derived from an alicyclic tetracarboxylic dianhydride.

4. 4. The dispersion composition according to claim 3, wherein the content of the structural unit UA relative to the total amount of structural units derived from the tetracarboxylic dianhydride constituting the polyamic acid is 5 mol % or more.

5. The dispersion composition according to any one of claims 1 to 4, wherein the dispersion medium comprises at least one selected from the group consisting of N-methylpyrrolidone, N-ethylpyrrolidone, and γ-butyrolactone.

6. 6. The dispersion composition according to claim 1, wherein the content of the dispersed substance is greater than 0% by mass and not more than 0.05% by mass relative to the total amount of the dispersion composition.

7. The dispersion composition according to any one of claims 1 to 6, wherein the dispersed substance is nanocarbon.

8. 8. The dispersion composition according to claim 7, wherein the nanocarbon is at least one selected from the group consisting of carbon black, carbon fiber, carbon nanotube, graphite, fullerene, and carbon nanohorn.

9. 9. The dispersion composition according to claim 1, wherein the content of the polyamic acid is 5,000 parts by mass or more and 50,000 parts by mass or less per 100 parts by mass of the substance to be dispersed.

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