Carbon nanotube membrane with substrate production method, self-supporting membrane of carbon nanotube membrane production method and laminate

Abstract

To provide a carbon nanotube membrane with a substrate production method where a membrane can be easily peeled from the substrate when being immersed into a liquid by suppressing the peeling of the membrane from the substrate when washing a spin coat and the like.SOLUTION: In a carbon nanotube membrane production method, a dispersion liquid dispersed with a plurality of carbon nanotubes is coated on a substrate and an unwashed carbon nanotube membrane is deposited, the unwashed carbon nanotube membrane is in contact with a washing liquid and a washed carbon nanotube membrane is made, the washed carbon nanotube membrane is dried, and the carbon nanotube membrane is made. The dispersion liquid includes a hydrophilic functional group. The washing liquid includes a solvent for the washing liquid. The Hansen solubility parameter of the solvent for the washing liquid is 22(MPa)0.5-30(MPa)0.5.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to a method for manufacturing a substrate-attached carbon nanotube film, a method for manufacturing a free-standing carbon nanotube film, and a laminate. [Background technology]

[0002] The miniaturization of semiconductor integrated circuits is being promoted by photolithography. In recent years, as semiconductor integrated circuits have become more highly precise, EUV (Extreme Ultra Violet) light has come to be used. EUV light has a short wavelength and is easily absorbed by gases, liquids, and solids. For this reason, in exposure methods using EUV light, a photomask having a reflective layer that reflects EUV light is used.

[0003] A pellicle is attached to the photomask to prevent foreign matter such as dust from adhering to the surface of the photomask. The pellicle includes a pellicle film and a pellicle frame that supports the pellicle film. A carbon nanotube (hereinafter, also referred to as "CNT") film (hereinafter, also referred to as "CNT film") is known as a pellicle film that is transparent to EUV light (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-181212 A Summary of the Invention [Problem to be solved by the invention]

[0005] A CNT film can be obtained, for example, by applying a dispersion containing CNTs onto a substrate by spin coating to obtain a substrate-attached CNT film, and then immersing the obtained substrate-attached CNT film in a liquid to separate it from the substrate.

[0006] However, in conventional methods, the CNT film may peel off from the substrate during deposition by spin coating, and when the substrate-attached CNT film is immersed in liquid, some of the CNT film may not peel off from the substrate. Therefore, there is a need for a method for producing a substrate-attached carbon nanotube film that can suppress peeling of the film from the substrate during film formation by spin coating and can produce a substrate-attached carbon nanotube film that can be easily peeled off from the substrate when immersed in a water bath. There is a need for a laminate from which the carbon nanotube film can be easily peeled off when immersed in a liquid.

[0007] The present disclosure has been made in consideration of the above circumstances. The problem to be solved by one embodiment of the present disclosure is to provide a method for producing a substrate-attached carbon nanotube film that can suppress peeling of the film from the substrate during cleaning such as spin coating, and produce a substrate-attached carbon nanotube film that easily peels off from the substrate when immersed in liquid, a method for producing a free-standing carbon nanotube film, and a laminate from which the carbon nanotube film easily peels off when immersed in liquid. [Means for solving the problem]

[0008] Means for solving the above problems include the following embodiments.

[0009] <1> Applying a dispersion liquid in which a plurality of carbon nanotubes are dispersed onto a hydrophilic substrate to form an unwashed carbon nanotube film; contacting the unwashed carbon nanotube film with a cleaning solution to produce a washed carbon nanotube film; drying the washed carbon nanotube film to produce a carbon nanotube film; having the dispersion comprises a hydrophilic functional group; The cleaning solution comprises a cleaning solution solvent, The Hansen solubility parameter of the cleaning solution solvent is 22 (MPa) 0.5 ~30(MPa) 0.5This is a method for producing a carbon nanotube film attached to a substrate. <2> The hydrophilic functional group is carboxylic acid (COO - ) group, a hydroxy group, a sulfone group, an amino group, and a silanol group. <1> 2. A method for producing a substrate-attached carbon nanotube film according to claim 1 . <3> In preparing the washed carbon nanotube film, the unwashed carbon nanotube film is contacted with a pretreatment liquid and then with the washing liquid; the pre-treatment liquid contains a pre-treatment liquid solvent, The Hansen solubility parameter of the pretreatment liquid solvent is 35 (MPa) 0.5 is as follows: When the dispersion liquid is acidic, the pre-treatment liquid is basic; When the dispersion liquid is basic, the pre-treatment liquid is acidic. <1> or <2> 2. A method for producing a substrate-attached carbon nanotube film according to claim 1 . <4> The dispersion is acidic, The pretreatment liquid is basic. <3> 2. A method for producing a substrate-attached carbon nanotube film according to claim 1 . <5> The solvent for the pre-treatment liquid includes at least one selected from the group consisting of cyclopentanone, dimethylacetamide, 2-butanol, N-methyl-2-pyrrolidone, 1-butanol, isopropyl alcohol, N,N-dimethylformamide, 1-propanol, γ-butyrolactone, ethanol, and methanol. <3> or <4> 2. A method for producing a substrate-attached carbon nanotube film according to claim 1 . <6> In preparing the washed carbon nanotube film, the pre-treatment liquid is spin-coated onto the uncleaned carbon nanotube film to bring the uncleaned carbon nanotube film into contact with the pre-treatment liquid, and then the cleaning liquid is spin-coated onto the uncleaned carbon nanotube film to bring the uncleaned carbon nanotube film into contact with the cleaning liquid; <3> ~ <5> 13. A method for producing a substrate-attached carbon nanotube film according to claim 12. <7> The cleaning solution solvent includes at least one selected from the group consisting of cyclopentanone, dimethylacetamide, 2-butanol, N-methyl-2-pyrrolidone, 1-butanol, isopropyl alcohol, N,N-dimethylformamide, 1-propanol, γ-butyrolactone, ethanol, and methanol. <1> ~ <6> 13. A method for producing a substrate-attached carbon nanotube film according to claim 12. <8> The dispersion liquid contains at least one selected from the group consisting of polyacrylic acid, a flavin derivative, sodium cholate, sodium deoxycholate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium polyacrylate, and an organic side chain flavin. <1> ~ <7> 13. A method for producing a substrate-attached carbon nanotube film according to claim 12. <9> The carbon nanotube film has a thickness of 100 nm or less. <1> ~ <8> 13. A method for producing a substrate-attached carbon nanotube film according to claim 12. <10> The above <1> ~ <9> preparing a substrate-attached carbon nanotube film manufactured by the method for manufacturing a substrate-attached carbon nanotube film according to any one of the above items; Providing a frame having a through hole; The carbon nanotube film is then immersed in a liquid to float the carbon nanotube film peeled off from the substrate on the liquid surface; scooping up the carbon nanotube film floating on the liquid surface with the frame to produce a free-standing carbon nanotube film in which the carbon nanotube film blocks one of the through-holes; The carbon nanotube film is then heated to a temperature of 300° C. for 30 minutes. <11> A laminate including a carbon nanotube film, The carbon nanotube film includes a plurality of carbon nanotubes. The carbon nanotube film has a nitrogen atom concentration of 1.0 at % or less. Effect of the Invention

[0010] According to one embodiment of the present disclosure, there is provided a method for producing a substrate-attached carbon nanotube film that can produce a substrate-attached carbon nanotube film that is easily peeled off from the substrate when immersed in a liquid by suppressing peeling of the film from the substrate during cleaning such as spin coating, and a method for producing a free-standing carbon nanotube film. According to another embodiment of the present disclosure, there is provided a laminate that is easily peeled off from the carbon nanotube film when immersed in a liquid. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] In the present disclosure, a numerical range indicated using "~" means a range that includes the numerical values ​​before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in the present disclosure, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in the present disclosure. In addition, in the numerical ranges described in the present disclosure, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples. In the present disclosure, combinations of two or more preferred embodiments are more preferred embodiments. In the present disclosure, when there are multiple substances corresponding to each component, the amount of each component means the total amount of the multiple substances, unless otherwise specified. In this specification, the term "process" refers not only to an independent process, but also to a process that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved. In this disclosure, "EUV light" refers to light having a wavelength of 1 nm or more and 30 nm or less. The wavelength of EUV light is preferably 5 nm or more and 13.5 nm or less.

[0012] (1) Method for manufacturing a carbon nanotube film on a substrate The manufacturing method of the carbon nanotube film with substrate (hereinafter also referred to as "substrate-mounted CNT film") of the present disclosure includes applying a dispersion liquid in which a plurality of carbon nanotubes (hereinafter also referred to as "CNTs") are dispersed onto a hydrophilic substrate (hereinafter also referred to as "hydrophilic substrate") to form an unwashed carbon nanotube film (hereinafter also referred to as "unwashed CNT film") (hereinafter also referred to as "film formation process"); contacting the unwashed carbon nanotube film with a washing liquid to prepare a washed carbon nanotube film (hereinafter also referred to as "washed CNT film") (hereinafter also referred to as "washing process"); and drying the washed carbon nanotube film to prepare a carbon nanotube film (hereinafter also referred to as "CNT film") (hereinafter also referred to as "drying process"). The dispersion liquid contains a hydrophilic functional group. The washing liquid contains a solvent for the washing liquid. The Hansen solubility parameter (hereinafter also referred to as "SP value") of the solvent for the washing liquid is 22 (MPa) 0.5 ~30(MPa) 0.5 The film forming step, the cleaning step, and the drying step are performed in this order.

[0013] The term "hydrophilic functional group" refers to a functional group that has a greater affinity for water when placed at the interface between water and oil. The "Hansen solubility parameter" can be expressed by the following formula (1) using the Hansen SP values ​​[δD, δP, δH]. Equation (1): SP value = "square root of (δD2, δP2, δH2)" The SP value is expressed in a three-dimensional space introduced by Hildebrand. The three-dimensional space consists of three components: a dispersion term δD, a polar term δP, and a hydrogen bond term δH. The dispersion term δD indicates the effect of dispersion forces. The polar term δP indicates the effect of dipole-dipole forces. The hydrogen bond term δH indicates the effect of hydrogen bonding forces. The definition and calculation of the SP value are described in Non-Patent Document 1 below. Non-patent document 1: Charles M. Hansen, Hansen Solubility Parameters: A Users Handbook (CRC Press, 2007)

[0014] When the solvent is a mixed solvent consisting of solvent A and solvent B, the SP value of the solvent can be calculated from the following formula (2). Equation (2): XA × δA + (1-XA) × δB In formula (2), "XA" represents the molar fraction of solvent A relative to the total amount of the mixed solvent. "δA" represents the SP value of solvent A. "1-XA" represents the molar fraction of solvent B relative to the total amount of the mixed solvent. "δB" represents the SP value of solvent B.

[0015] When the solvent is a mixed solvent consisting of solvent A, solvent B, and solvent C, the SP value of the solvent can be calculated from the following formula (3). Formula (3): XA×δA+XB×δB+XC×δC In formula (3), "XA" represents the molar fraction of solvent A relative to the total amount of the mixed solvent. "δA" represents the SP value of solvent A. XB represents the molar fraction of solvent B relative to the total amount of the mixed solvent. "δB" represents the SP value of solvent B. XC represents the molar fraction of solvent C relative to the total amount of the mixed solvent. "δC" represents the SP value of solvent C.

[0016] When the solvent is four components, the calculation can be performed in the same manner as when the solvent is three components.

[0017] The method for producing a substrate-attached CNT film of the present disclosure has the above-mentioned configuration, and therefore can produce a substrate-attached CNT film that is easily peeled off from the substrate when immersed in liquid, while suppressing peeling of the film from the substrate during film formation during cleaning such as spin coating.

[0018] The reason why the present disclosure has an effect is not entirely clear, but is presumed to be as follows. In the present disclosure, in the film formation step, a dispersion liquid containing hydrophilic functional groups is applied onto a hydrophilic substrate to form an unwashed CNT film. As a result, the unwashed CNT film has hydrophilic functional groups at the sites that come into contact with the hydrophilic substrate. The hydrophilic functional groups have affinity for the hydrophilic substrate. As a result, when the unwashed CNT film is formed by spin coating, the unwashed CNT film is unlikely to peel off from the hydrophilic substrate. In the washing step, the unwashed CNT membrane is brought into contact with a specific washing liquid to produce a washed CNT membrane. At this time, the hydrophilic functional groups on the surface portion of the unwashed CNT membrane (hereinafter also referred to as the "surface portion") are easily removed. Therefore, the number of hydrophilic functional groups on the surface portion of the washed CNT membrane is relatively small. In addition, in the washing step, a layer containing an appropriate amount of hydrophilic functional groups (hereinafter also referred to as the "intermediate layer") is easily formed between the unwashed CNT membrane and the hydrophilic substrate. As a result, after the drying step is performed, the surface portion of the CNT membrane is hydrophobic and the intermediate layer is hydrophilic. When the CNT film with the substrate is immersed in a liquid (e.g., water) with an SP value of 35 or more (hereinafter also referred to as the "specific liquid"), an air layer is formed on the surface of the CNT film due to the hydrophobic surface portion of the CNT film, and the specific liquid penetrates between the CNT film and the substrate due to the presence of an intermediate layer that is compatible with the specific liquid. At this time, the pressure of the specific liquid (e.g., water pressure) in the direction of pressing the CNT film from the surface portion side to the substrate side is difficult to apply to the CNT film. Therefore, the specific liquid penetrates between the CNT film and the hydrophilic substrate, and the CNT film is pushed in the direction of peeling it off from the substrate. As a result, the CNT film is easily peeled off from the hydrophilic substrate when immersed in the specific liquid bath. For these reasons, it is presumed that the method for producing a substrate-attached CNT film disclosed herein can suppress peeling of an unwashed CNT film from the substrate during film formation by spin coating, and can produce a substrate-attached CNT film in which the CNT film is easily peeled off from the hydrophilic substrate when immersed in a specific liquid bath.

[0019] (1.1) Film formation process In the film formation process, a dispersion liquid in which multiple CNTs are dispersed is applied onto a hydrophilic substrate to form an unwashed CNT film.

[0020] (1.1.1) Dispersion liquid A plurality of CNTs are dispersed in the dispersion liquid.

[0021] The dispersion liquid contains a hydrophilic functional group. The hydrophilic functional group is, for example, a carboxylic acid (COO - ) group, hydroxy group, sulfone group, amino group, and silanol group. Among them, the hydrophilic functional group is carboxylic acid (COO - It is preferable that the hydrophilic functional group contains at least one selected from the group consisting of a carboxylic acid (COO - ) group and hydroxy group. This allows the cleaning solution to have a moderately high solubility of the dispersant residue in the cleaning solution solvent when the cleaning solution contains a dispersant and the cleaning solution solvent has an SP value of 22 to 30. Therefore, when the cleaning step is performed, most of the dispersant residue is dissolved in the cleaning solution solvent from the surface of the uncleaned CNT membrane. This means that in the substrate-attached CNT membrane, the "amount of components derived from the dispersant in the intermediate layer" tends to be greater than the "amount of components derived from the dispersant on the surface of the CNT membrane". As a result, the CNT membrane is more easily peeled off from the hydrophilic substrate when immersed in a liquid.

[0022] The dispersion may contain a solvent for the dispersion, which will be described later, and other components, which will be described later. The hydrophilic functional group contained in the dispersion may be derived from the solvent for the dispersion, or may be derived from other components, such as a surfactant.

[0023] The dispersion may be acidic, neutral, or basic. "The dispersion is acidic" means that the pH of the dispersion is less than 7. "The dispersion is neutral" means that the pH of the dispersion is 7. "The dispersion is basic" means that the pH of the dispersion is greater than 7.

[0024] The dispersion liquid is preferably acidic. When the dispersion liquid is acidic, a decrease in the stability of the dispersion liquid caused by the dispersion liquid absorbing carbon dioxide in the atmosphere during storage is suppressed. The pH of the dispersion is preferably 2 to 6, more preferably 2.2 to 5. For example, the dispersion can be adjusted to be acidic by adding polyacrylic acid as a dispersant to be described later to the dispersion and adjusting the concentration of polyacrylic acid. The pH is measured by neutralization titration.

[0025] (1.1.1.1) Carbon nanotubes The dispersion includes a plurality of CNTs.

[0026] The CNT is not particularly limited, and may be a single-wall CNT (hereinafter also referred to as a "single-wall CNT") or a multi-wall CNT (hereinafter also referred to as a "multi-wall CNT").

[0027] The CNTs may form bundles (bundle structures). The number of CNTs forming a bundle is 3 or more, and preferably 4 to 100. The CNTs may be at least one of single-walled CNTs and multi-walled CNTs. The CNTs do not have to form bundles.

[0028] The outer diameter of the CNT tube (i.e., the width of the CNT) may be 0.8 nm to 400 nm. The "outer diameter of the CNT tube" refers to the outer diameter of a single tube when the CNT exists as a single fiber in the CNT film, and refers to the outer diameter of a single bundle when the CNT exists as a bundle (i.e., a bundle). The thickness (outer diameter) of a bundle formed of single-walled CNTs may be 4 nm to 400 nm. The thickness (outer diameter) of a bundle formed of multi-walled CNTs may be 4 nm to 400 nm. The length of the CNTs is preferably 10 nm to 10 cm. When the length of the CNTs is 10 nm or more, the CNTs are well entangled with each other, and the mechanical strength of the CNT film is excellent.

[0029] The outer diameter and length of the CNT tube are the arithmetic average values ​​measured for 20 or more carbon materials (primary particles) by observation with an electron microscope. As the electron microscope, a scanning electron microscope (SEM), a transmission electron microscope (TEM), or the like can be used.

[0030] The CNTs may be synthesized by a direct injection pyrolysis synthesis method (hereinafter referred to as the "e-DIPS method"). An example of a commercially available product of the CNTs synthesized by the e-DIPS method is the product name "MEIJO eDIPS" manufactured by Meijo Nano Carbon Co., Ltd.

[0031] The content of CNT is preferably 0.0001% by mass to 1% by mass, and more preferably 0.001% by mass to 0.1% by mass, based on the total amount of the dispersion.

[0032] (1.1.1.2) Dispersion Solvent The dispersion typically contains a dispersion solvent.

[0033] The solvent for the dispersion liquid is not particularly limited, and examples thereof include carboxylic acids (COO - ) group, solvents having a hydroxy group, solvents having a sulfone group, solvents having an amino group, esters, ketones, ethers, and aromatic hydrocarbons. Carboxylic acid (COO - ) group, for example, acetic acid, organic acids, etc. Examples of the solvent having a hydroxyl group include water and alcohols, etc. Examples of the alcohols include methanol, ethanol, n-propanol, 2-propanol (isopropanol), n-butanol, isobutanol, t-butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, and amyl alcohol. Examples of the solvent having a sulfone group include methyl sulfone, ethyl phenyl sulfone, diethyl sulfone, diphenyl sulfone, sulfolane, bisphenol S, sorapsone, dapsone, bisphenol A polysulfone, and sulfolane. Examples of solvents having an amino group include amide polar organic solvents, dimethylacetamide, and aminosilane. Examples of amide polar organic solvents include N,N-dimethylformamide and N-methylpyrrolidone. Aminosilane refers to a compound represented by H3SiNH2. Examples of esters include ethyl acetate and butyl acetate. Examples of ketones include acetone, methyl ethyl ketone, and cyclohexanone. Examples of ethers include diethyl ether, dioxane, and tetrahydrofuran. Examples of aromatic hydrocarbons include toluene, xylene, chlorobenzene, orthodichlorobenzene, and paradichlorobenzene. The dispersion solvent may be used alone or in combination of two or more kinds.

[0034] When the dispersion contains a solvent for the dispersion, the content of the solvent for the dispersion is preferably 90% by mass to 99.9999% by mass, and more preferably 99% by mass to 99.999% by mass, based on the total amount of the dispersion.

[0035] (1.1.1.3) Other ingredients The dispersion may contain other ingredients.

[0036] The other components are not particularly limited as long as they are known components that can be contained in the dispersion liquid or carbon film of the fibrous carbon nanostructure. For example, the dispersion liquid preferably contains a dispersant as the other component. The dispersant is not particularly limited as long as it can disperse the fibrous carbon nanostructure and can be dissolved in the solvent in which the fibrous carbon nanostructure is dispersed. Examples of the dispersant include surfactants, synthetic polymers, and natural polymers. The other components may be used alone or in combination of two or more.

[0037] Examples of the surfactant include anionic surfactants, cationic surfactants, and nonionic surfactants. Specific examples of the surfactant include polyacrylic acid, flavin derivatives, sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium deoxycholate, sodium cholate, sodium dodecylbenzenesulfonate, sodium polyacrylate, and organic side chain flavin. Examples of synthetic polymers include polyether diols, polyester diols, polycarbonate diols, polyvinyl alcohol, partially saponified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, acetal group-modified polyvinyl alcohol, butyral group-modified polyvinyl alcohol, silanol group-modified polyvinyl alcohol, ethylene-vinyl alcohol copolymers, ethylene-vinyl alcohol-vinyl acetate copolymer resins, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, acrylic resins, epoxy resins, modified epoxy resins, phenoxy resins, modified phenoxy resins, phenoxy ether resins, phenoxy ester resins, fluorine-based resins, melamine resins, alkyd resins, phenolic resins, polyacrylamides, polyacrylic acids, polystyrene sulfonic acids, polyethylene glycols, and polyvinylpyrrolidone. Examples of natural polymers include polysaccharides such as starch, pullulan, dextran, dextrin, guar gum, xanthan gum, amylose, amylopectin, alginic acid, gum arabic, carrageenan, chondroitin sulfate, hyaluronic acid, curdlan, chitin, chitosan, and cellulose, as well as salts or derivatives thereof.

[0038] The dispersion preferably contains at least one selected from the group consisting of polyacrylic acid, flavin derivatives, sodium cholate, sodium deoxycholate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium polyacrylate, and organic side chain flavin. This makes it easier for the CNTs to be loosened from clumps to single fibers by stirring the dispersion (e.g., stirring with a stirrer, etc.). Therefore, the variation in film thickness (roughness) of the unwashed CNT film formed by spin coating is smaller. As a result, a CNT film with a more uniform film thickness is obtained.

[0039] Among them, it is more preferable that the dispersion liquid contains polyacrylic acid. This ensures the flatness of the unwashed CNT film formed by spin coating. Furthermore, if the washing step includes a neutralization process described below, the CNT film is more easily peeled off from the hydrophilic substrate when immersed in the liquid.

[0040] When the dispersion contains other components, the content of the other components is preferably 0.0001% by mass to 50% by mass, and more preferably 0.001% by mass to 10% by mass, relative to the total amount of the dispersion. The content of the other components is not particularly limited, and is preferably 10 parts by mass to 1000 parts by mass, and more preferably 30 parts by mass to 500 parts by mass, relative to the total amount of CNTs.

[0041] (1.1.1.4) Method of mixing dispersion liquid The method for mixing the dispersion is not particularly limited, and examples thereof include a method using cavitation (ultrasonic dispersion method), a method of mechanically applying shear force (magnetic stirrer, ball mill, roller mill, vibration mill, kneader, homogenizer, etc.), and a method using turbulence (jet mill, Nanomizer, etc.).

[0042] (1.1.2) Hydrophilic substrate The hydrophilic substrate has hydrophilicity. In the hydrophilic substrate, at least the portion that comes into contact with the CNT film (hereinafter, also referred to as the "contact portion") needs to have hydrophilicity.

[0043] The shape of the hydrophilic substrate is not particularly limited, and examples thereof include a circle, a rectangle, etc. The thickness of the hydrophilic substrate is not particularly limited, and is preferably 100 μm to 1000 μm. The roughness Ra of the hydrophilic substrate is not particularly limited, and may be, for example, 10 μm or less.

[0044] The material of the hydrophilic substrate is not particularly limited, and examples thereof include glass materials, silicon (Si), etc. Examples of glass materials include quartz glass (silicon oxide (SiO2)), soda glass, borosilicate glass, sapphire, etc. Among these, the material of the hydrophilic substrate is preferably silicon that has been subjected to a hydrophilic treatment, which makes it easier to obtain a highly flat CNT film.

[0045] The hydrophilic substrate may be subjected to a hydrophilization treatment. The "hydrophilization treatment" refers to a treatment for forming hydrophilic functional groups on the surface of the hydrophilic substrate. Examples of the hydrophilization treatment include UV (Ultra Violet) ozone treatment and plasma treatment. When the material of the hydrophilic substrate is silicon (Si), the hydrophilic substrate having silanol formed on the surface is obtained by subjecting the surface of the hydrophilic substrate to the hydrophilization treatment.

[0046] (1.1.3) Method of applying dispersion The method of applying the dispersion is not particularly limited, and examples thereof include spin coating, dip coating, bar coating, spray coating, and electrospray coating. Among these, the method of applying the dispersion is preferably spin coating. This makes it easier to control the film thickness to a desired value by controlling the rotation speed, etc.

[0047] (1.2) Cleaning process In the washing step, the unwashed CNT membrane is brought into contact with a washing solution to produce a washed CNT membrane. The washing solution contains a solvent for the washing solution. By bringing the unwashed CNT membrane into contact with the washing solution, the surface portion of the washed CNT is made hydrophobic and an intermediate layer is formed between the washed CNT membrane and the hydrophilic substrate.

[0048] In the present disclosure, in the cleaning step, it is preferable to contact the uncleaned CNT membrane with a pretreatment liquid and then with the cleaning liquid. The pretreatment liquid contains a solvent for the pretreatment liquid. The Hansen solubility parameter of the solvent for the pretreatment liquid is 35 (MPa) or less. 0.5 The following are the conditions. When the dispersion is acidic, the pretreatment liquid is basic. When the dispersion is basic, the pretreatment liquid is acidic. By carrying out the pretreatment, the bonding strength between hydrophilic functional groups (for example, the bonding strength of hydrogen bonds) is weakened. Therefore, in the cleaning step, by contacting the uncleaned CNT film with the pretreatment liquid and then with the cleaning liquid, an appropriate amount of hydrophilic functional groups contained in the uncleaned CNT film is easily removed. As a result, the CNT film is more easily peeled off from the hydrophilic substrate when immersed in liquid.

[0049] Hereinafter, contacting the unwashed CNT membrane with the pretreatment liquid is also referred to as a "neutralization process." Contacting the unwashed CNT membrane with the cleaning liquid is also referred to as a "cleaning process."

[0050] The washing step may include a neutralization process depending on the pH of the dispersion liquid, from the viewpoint of more easily peeling off the CNT film from the hydrophilic substrate when immersed in a liquid. In particular, when the pH of the dispersion liquid is 7, the washing step may not include a neutralization process. When the pH of the dispersion liquid is not 7, it is preferable that the washing step includes a neutralization process.

[0051] The case where the cleaning step includes a neutralization process will be described below.

[0052] (1.2.1) Neutralization process In the neutralization process, as described above, the unwashed CNT film is brought into contact with the pretreatment liquid. As a result, when the dispersion liquid is acidic or basic, the bonding strength between the hydrophilic functional groups (e.g., the bonding strength of hydrogen bonds) is weakened compared to when the cleaning step does not include the neutralization process. Therefore, in the cleaning step, the unwashed CNT film is brought into contact with the pretreatment liquid and then with the cleaning liquid, so that an appropriate amount of the hydrophilic functional groups contained in the unwashed CNT film are easily removed. As a result, the CNT film is more easily peeled off from the hydrophilic substrate when immersed in the liquid.

[0053] It is preferable that the dispersion liquid is acidic and the pre-treatment liquid is basic. "The pre-treatment liquid is basic" means that the pH of the pre-treatment liquid is greater than 7. When the dispersion liquid contains a dispersant, the pre-treatment liquid is basic, and therefore the acidic dispersant can be neutralized and the ionic bond between the molecules of the dispersant can be weakened. The pH of the pretreatment liquid is preferably 8 to 20, and more preferably 9 to 14. Methods for adjusting the pretreatment liquid to be basic include adjusting the concentration of a basic material.

[0054] In the present disclosure, the dispersion liquid may be acidic and the pretreatment liquid may be basic. This makes it easier to stabilize the formation of the unwashed CNT film by a spin coater. Furthermore, in the first peeling step or the second peeling step described below, the peeling of the CNT film from the hydrophilic substrate, the lifting of the peeled CNT film, and the frame transfer step of the CNT film can be performed with good reproducibility.

[0055] (1.2.1.1) Pretreatment solution The pre-treatment liquid contains a pre-treatment liquid solvent.

[0056] The SP value of the pretreatment solvent is 35 (MPa). 0.5 The SP value of the pretreatment solvent is 3530 (MPa) or less. 0.5The fact that the SP value of the dispersion solvent is 35 (MPa) or less indicates that the solvent is not likely to aggregate. This means that even if the pre-treatment solvent gets between the unwashed CNT film and the hydrophilic substrate, the pre-treatment solvent is not likely to aggregate. Therefore, the force pushing the CNT film toward the surface portion of the CNT film is greater than the SP value of the dispersion solvent of 35 (MPa). 0.5 As a result, the peeling of the CNT film from the hydrophilic substrate can be suppressed during the neutralization process. The SP value of the pretreatment solution solvent is preferably 32.0 (MPa) from the viewpoint of easily suppressing peeling of the unwashed CNT film from the hydrophilic substrate. 0.5 Less than or equal to 29.0 (MPa), more preferably 29.0 (MPa) 0.5 More preferably, 25.0 (MPa) or less. 0.5 The SP value of the pretreatment solvent is 18.0 (MPa). 0.5 or more, 20.0 (MPa) 0.5 From these viewpoints, the SP value of the pre-treatment solution solvent may be 18.0 (MPa) or more. 0.5 ~35.0(MPa) 0.5 Preferably, the pressure is 20.00 (MPa). 0.5 ~32.0(MPa) 0.5 It is.

[0057] SP value is 30 (MPa) 0.5 Examples of the pre-treatment liquid solvent include cyclopentanone, dimethylacetamide, 2-butanol, N-methyl-2-pyrrolidone, 1-butanol, isopropyl alcohol, N,N-dimethylformamide, 1-propanol, γ-butyrolactone, ethanol, methanol, and dimethylacetamide. The pre-treatment liquid solvent may be used alone or in combination of two or more.

[0058] Among them, the pre-treatment liquid solvent preferably contains at least one selected from the group consisting of cyclopentanone, dimethylacetamide, 2-butanol, N-methyl-2-pyrrolidone, 1-butanol, isopropyl alcohol, N,N-dimethylformamide, 1-propanol, γ-butyrolactone, ethanol, and methanol. This makes it easier to neutralize the dispersant entangled in the CNT film without causing cracks in the CNT film when the dispersion liquid contains a dispersant.

[0059] The content of the solvent for the pre-treatment liquid is preferably 90% by mass to 99.999% by mass, and more preferably 99% by mass to 99.9999% by mass, based on the total amount of the pre-treatment liquid.

[0060] (1.2.1.2) Additives The pretreatment liquid may contain additives.

[0061] Examples of the additives include alkali, pH buffers as pH stabilizers, surfactants, etc. The additives may be used alone or in combination of two or more.

[0062] Examples of the alkali include ammonia, amine metal hydroxides (e.g., sodium hydroxide, potassium hydroxide, etc.), ammonium fluoride, potassium fluoride, sodium fluoride, polyethyleneimine, and amines. Examples of the amines include quaternary ammonium hydroxides (e.g., tetrabutylammonium hydroxide (TBAOH), bis(2-hydroxyethyl)dimethylammonium hydroxide, tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), etc.), and ammonium fluoride.

[0063] When the dispersion liquid is acidic and the pre-treatment liquid is basic, the pre-treatment liquid preferably contains at least one selected from the group consisting of ammonia, quaternary ammonium hydroxide, metal hydroxide, ammonium fluoride, potassium fluoride, and sodium fluoride (hereinafter also referred to as "alkaline agent"). This makes it possible to suppress a decrease in the stability of the dispersion liquid compared to when the pre-treatment liquid does not contain the above-mentioned alkaline agent, while making it easier to remove an appropriate amount of hydrophilic functional groups contained in the unwashed CNT membrane by contacting the unwashed CNT membrane with the pre-treatment liquid and then with the washing liquid in the washing step.

[0064] The pre-treatment liquid preferably contains tetrabutylammonium hydroxide (TBAOH) as an alkali, which improves work safety and allows safe handling during maintenance work in mass production facilities, as compared with a case in which the pre-treatment liquid contains tetramethylammonium hydroxide (TMAH) as an alkali.

[0065] When the pre-treatment liquid contains an alkali, the content of the alkali is preferably 0.001% by mass to 30% by mass, and more preferably 0.1% by mass to 10% by mass, relative to the total amount of the pre-treatment liquid. The content of the alkali is preferably 1 part by mass to 1000 parts by mass, and more preferably 10 parts by mass to 100 parts by mass, based on the total amount of the unwashed CNT film.

[0066] When the dispersion contains polyacrylic acid as a dispersant and the pretreatment liquid contains tetrabutylammonium hydroxide as an alkali, the solvent for the pretreatment liquid preferably contains ethanol. This allows the neutral salts of polyacrylic acid and tetrabutylammonium hydroxide to remain in the unwashed CNT film more appropriately than when the solvent for the pretreatment liquid contains only isopropyl alcohol or when the solvent for the pretreatment liquid contains only water. As a result, when spin coating is performed in the cleaning process, peeling of the unwashed CNT film from the hydrophilic substrate is more suppressed. In addition, in the first peeling step and the second peeling step described below, the CNT film is more easily peeled off from the hydrophilic substrate. Furthermore, the time required for the neutralization process can be significantly reduced.

[0067] In this disclosure, the term "neutralized salt" refers to a mixture of an acidic material (cation), a basic material (anion), and a trace amount of water. The amount of water contained may be the same as the amount of water contained in ethanol. The neutralized salt may be an organic salt (i.e., a neutralized salt of polyacrylic acid and tetrabutylammonium hydroxide) or an inorganic salt (e.g., potassium hydroxide, sodium hydroxide, etc.), but is preferably an organic salt that is more easily tolerated by an exposure machine.

[0068] (1.2.1.3) Mixing method of pre-treatment liquid The method for mixing the pre-treatment liquid is not particularly limited, and may be the same as the methods exemplified as the methods for mixing the dispersion liquid.

[0069] (1.2.1.4) Contact method The method of contacting the unwashed CNT film with the pretreatment liquid is not particularly limited, and examples thereof include spin coating, dip coating, bar coating, spray coating, and electrospray coating. Among these, the method of applying the pretreatment liquid is preferably spin coating. This allows the pretreatment liquid to be uniformly spread over the entire unwashed CNT film, and then the excess pretreatment liquid can be quickly removed by spin rotation after the neutralization process is performed.

[0070] (1.2.2) Cleaning process In the cleaning process, the unwashed CNT film is contacted with a cleaning solution to produce a washed CNT film.

[0071] (1.2.2.1) Cleaning solution The cleaning solution cleans the uncleaned CNT membrane.

[0072] (1.2.2.2) Cleaning solvents The cleaning solution includes a cleaning solution solvent.

[0073] The SP value of the cleaning solvent is 22 (MPa). 0.5 ~30(MPa) 0.5 The SP value of the cleaning solvent is 30 (MPa). 0.5 Because the SP value is higher than 1000 nm, the hydrophilic functional groups on the surface of the unwashed CNT film (hereinafter also referred to as the "surface portion") are easily removed. Therefore, the number of hydrophilic functional groups on the surface of the washed CNT film is relatively small. In addition, a layer containing an appropriate amount of hydrophilic functional groups (hereinafter also referred to as the "intermediate layer") is easily formed between the unwashed CNT film and the hydrophilic substrate. As a result, when spin coating is performed in the washing process, peeling of the film from the hydrophilic substrate is suppressed, and the CNT film with the substrate can be easily floated on the liquid surface by immersing it in a liquid. The SP value of the cleaning solvent is preferably 30.0 (MPa) from the viewpoint of easily suppressing peeling of the film from the hydrophilic substrate during the cleaning process. 0.5 Less than or equal to 27.0 (MPa), more preferably 0.5 More preferably, 25.0 (MPa) or less. 0.5 The following is the result. The SP value of the cleaning solvent is preferably 23 (MPa). 0.5 More preferably, 23.5 (MPa) 0.5 More preferably, 24.0 (MPa) 0.5 The SP value of the cleaning solvent is 23 (MPa). 0.5 If the above conditions are met, peeling with a liquid can be easily performed in the next step of forming the substrate into a self-supporting structure.

[0074] SP value is 22 (MPa) 0.5 ~30(MPa)0.5 Examples of the cleaning solution solvent include cyclopentanone, 2-butanol, N-methyl-2-pyrrolidone, 1-butanol, isopropyl alcohol, N,N-dimethylformamide, 1-propanol, γ-butyrolactone, ethanol, methanol, dimethylacetamide, etc. The cleaning solution solvent may be used alone or in combination of two or more.

[0075] Among them, the cleaning solution solvent preferably contains at least one selected from the group consisting of cyclopentanone, dimethylacetamide, 2-butanol, N-methyl-2-pyrrolidone, 1-butanol, isopropyl alcohol, N,N-dimethylformamide, 1-propanol, γ-butyrolactone, ethanol, and methanol, which can prevent cracks caused by peeling of the CNT film from the hydrophilic substrate and can remove the neutralizing dispersant from the surface of the CNT film.

[0076] The content of the solvent for the cleaning liquid is preferably 99.5% by mass to 100% by mass, and more preferably 99.9% by mass to 100% by mass, based on the total amount of the cleaning liquid.

[0077] (1.2.2.3) Additives The cleaning liquid may contain known additives as necessary.

[0078] (1.2.2.4) How to mix the cleaning solution The method for mixing the cleaning liquid is not particularly limited, and may be the same as the method exemplified as the method for mixing the dispersion liquid.

[0079] (1.2.2.5) Contact method The method of contacting the unwashed CNT film with the cleaning liquid is not particularly limited, and examples thereof include spin coating, dip coating, bar coating, spray coating, and electrospray coating. Among these, the method of applying the cleaning liquid is preferably spin coating. This allows the CNT film to be uniformly spread over the entire surface of the CNT film, and allows the neutralized dispersant to be quickly removed from the surface of the CNT film.

[0080] (1.2.3) Preferred embodiments In the present disclosure, in preparing the washed CNT film (i.e., in the washing step), it is preferable to spin-coat the pre-treatment liquid onto the unwashed CNT film, bring the unwashed CNT film into contact with the pre-treatment liquid, and then spin-coat the washing liquid onto the washed CNT film, bring the washing liquid into contact with the unwashed CNT film. This allows the neutralization salt to remain in the washed CNT film to a moderate extent, compared to the case where spin-coating is not performed in the neutralization process and washing process. Therefore, it is possible to easily float the CNT film on the liquid surface while suppressing peeling of the washed CNT film during spin rotation of the spin coater.

[0081] (1.3) Drying process In the drying step, the washed CNT film is dried to produce a CNT film. This allows the solvent in the washed CNT film to volatilize. By carrying out the drying step, the CNT film immersed in the liquid is more likely to peel off from the hydrophilic substrate and float on the liquid surface in the first peeling step and the second peeling step described below than in the case where the drying step is not carried out.

[0082] The method for drying the washed CNT film is not particularly limited, and examples thereof include a method of heating using a heating device and a method of natural drying. Examples of heating devices include a hot plate, an infrared lamp, an oven, and a hot air dryer. The drying step is preferably carried out at 40° C. or less for a short period of time (for example, 5 minutes or less) so that the neutralizing dispersant is less likely to react with heat and deteriorate. The drying method is preferably carried out by rotating with a spin coater.

[0083] (1.3.1)CNT film The thickness of the CNT film is not particularly limited and can be, for example, 2 nm to 200 nm. The thickness of the CNT film is preferably 100 nm or less. With the method for producing a substrate-attached CNT film according to the present disclosure, even if the CNT film has a thickness of 100 nm or less, the CNT film can be easily peeled off from the substrate without wrinkles when immersed in a liquid. From the viewpoint of increasing the transmittance of EUV light, the thickness of the CNT film is preferably 100 nm or less, more preferably 90 nm or less, further preferably 80 nm or less, particularly preferably 40 nm or less, and even more preferably 30 nm or less. From the viewpoint of the breakage resistance of the CNT film and the viewpoint of foreign matter blocking properties (i.e., the viewpoint of preventing foreign matter from passing through the CNT film), the thickness of the CNT film is preferably 4 nm or more, more preferably 6 nm or more, even more preferably 10 nm or more, particularly preferably 50 nm or more, and even more preferably 60 nm or more. From these viewpoints, the thickness of the CNT film is preferably 2 nm to 100 nm, more preferably 6 nm to 90 nm, even more preferably 10 nm to 90 nm, particularly preferably 50 nm to 90 nm, and even more preferably 60 nm to 80 nm.From another viewpoint, the thickness is more preferably 2 nm to 50 nm, even more preferably 2 nm to 40 nm, particularly preferably 2 nm to 30 nm, and even more preferably 4 nm to 30 nm. The thickness of the CNT film is measured by transferring the CNT film onto a silicon substrate and using a reflection spectroscopic film thickness meter (for example, F50-UV manufactured by Filmetrics, Inc.).

[0084] The material of the CNT film may be the same as that exemplified as the CNT in the film forming step described above. The material of the CNT film is the same as the material of the CNT in the dispersion liquid.

[0085] The CNT film may have a neutralized salt attached thereto, which will be described later.

[0086] (2) Manufacturing method of laminate The method for producing a laminate of the present disclosure includes preparing a substrate-attached CNT film produced by the method for producing a substrate-attached CNT film of the present disclosure (hereinafter also referred to as a "first preparation step"), immersing the substrate-attached CNT film in a liquid to float the CNT film peeled off from the hydrophilic substrate on the liquid surface (hereinafter also referred to as a "first peeling step"), and scooping up the CNT film floating on the liquid surface (hereinafter also referred to as a "first scooping step"). The first preparation step, first peeling step, and first scooping step are performed in this order.

[0087] The method for producing a laminate according to the present disclosure has the above-described configuration, so that a laminate in which a CNT film is transferred to a desired member can be obtained.

[0088] (2.1) First preparation step In the first preparation step, a substrate-attached CNT film manufactured by the method for manufacturing a substrate-attached CNT film of the present disclosure is prepared. The method for preparing the substrate-attached CNT film is the same as the method exemplified as the method for manufacturing a substrate-attached CNT film of the present disclosure.

[0089] (2.2) First peeling process In the first peeling step, the substrate-attached CNT film is immersed in a liquid, and the CNT film peeled off from the hydrophilic substrate is floated on the surface of the liquid.

[0090] The liquid is not particularly limited as long as it can float the CNT film. Examples of the liquid include water and aqueous solutions containing inorganic substances, and the liquid preferably has an SP value of 35 or more.

[0091] The method for immersing the laminate in the liquid is not particularly limited, and any known method may be used.

[0092] (2.3) First scooping process In the first scooping step, the CNT film floating on the liquid surface is scooped up. This results in a laminate in which the CNT film is transferred to a desired member. Furthermore, according to the method for manufacturing the laminate, fragments of the CNT film are less likely to adhere to the CNT film.

[0093] The adherend that scoops up the CNT membrane is not particularly limited as long as it can scoop up the CNT membrane floating on the liquid surface, and is appropriately selected depending on the application of the CNT membrane. Examples of the adherend include a flat plate-like object without a through hole, a base material with a through hole in the center of the main surface, and a pellicle frame. The material of the adherend is not particularly limited, and the same material as the hydrophilic substrate can be used. Details of the pellicle frame will be described later.

[0094] (3) Manufacturing method for free-standing carbon nanotube film The method for producing a free-standing film of carbon nanotubes (hereinafter also referred to as a "CNT free-standing film") of the present disclosure includes preparing a substrate-attached CNT film produced by the substrate-attached CNT film production method of the present disclosure (hereinafter also referred to as a "second preparation step"); preparing a frame (hereinafter also referred to as a "frame") having a through hole (hereinafter also referred to as a "third preparation step"); immersing the substrate-attached CNT film in a liquid to float the CNT film peeled off from the substrate on the liquid surface (hereinafter also referred to as a "second peeling step"); and scooping up the CNT film floating on the liquid surface with the frame to produce a CNT free-standing film in which the CNT film blocks one of the through holes (hereinafter also referred to as a "second scooping step"). The order of performing the second preparation step and the third preparation step is not particularly limited. The second preparation step and the third preparation step are performed before performing the second peeling step. The second preparation step and the third preparation step are performed before performing the second scooping step.

[0095] The method for producing a CNT freestanding film disclosed herein has the above-described configuration, and therefore can suppress peeling of an unwashed CNT film from a hydrophilic substrate during cleaning such as spin coating, and can easily peel the CNT film from the hydrophilic substrate when immersed in a liquid, thereby producing a CNT freestanding film.

[0096] (3.1) Second preparation process In the second preparation step, a substrate-attached CNT film manufactured by the method for manufacturing a substrate-attached CNT film of the present disclosure is prepared. The method for preparing the substrate-attached CNT film is the method for producing a substrate-attached CNT film of the present disclosure.

[0097] (3.2) Third preparation process In the second preparation step, a frame is prepared. The frame may be a pellicle frame or a frame different from the pellicle frame as long as it has a through hole.

[0098] (3.2.1) Pellicle frame The pellicle frame has an exposure through hole, which is a space through which light transmitted through the CNT film passes to reach the photomask.

[0099] The shape of the pellicle frame in the thickness direction of the pellicle frame is, for example, a rectangle. The rectangle may be a square or a rectangle.

[0100] The pellicle frame may have an air vent formed, for example, in a side surface of the pellicle frame. When the pellicle frame is attached to the photomask, the air vent communicates the internal space of the pellicle with the external space of the pellicle.

[0101] The rectangular pellicle frame is composed of four sides when viewed in the thickness direction. The length of one side in the longitudinal direction is preferably 200 mm or less. The size of the pellicle frame is standardized according to the type of exposure device. The length of one side of the pellicle frame in the longitudinal direction being 200 mm or less satisfies the standardized size for exposure using EUV light. The length of one side in the short direction can be, for example, 5 mm to 180 mm, preferably 80 mm to 170 mm, and more preferably 100 mm to 160 mm. The height of the pellicle frame (i.e., the length of the pellicle frame in the thickness direction) is not particularly limited, but is preferably 3.0 mm or less, more preferably 2.4 mm or less, and even more preferably 2.375 mm or less. This allows the pellicle frame to meet the size standardized for EUV exposure. The height of the pellicle frame standardized for EUV exposure is, for example, 2.375 mm. The mass of the pellicle frame is not particularly limited, but is preferably 20 g or less, and more preferably 15 g or less, which makes the pellicle frame suitable for use in EUV exposure.

[0102] The material of the pellicle frame is not particularly limited, and examples thereof include quartz glass, metal, carbon-based materials, resin, silicon, and ceramic-based materials. The metal may be a pure metal or an alloy. A pure metal is made of a single metal element. Examples of pure metals include aluminum and titanium. An alloy is made of multiple metal elements, or a metal element and a nonmetal element. Examples of alloys include stainless steel, magnesium alloys, steel, carbon steel, and Invar. Examples of resins include polyethylene. Examples of ceramic materials include silicon nitride (SiN), silicon carbide (SiC), and alumina (Al2O3).

[0103] The structure of the pellicle frame may be a single item or an assembly. A "single item" is one obtained by cutting out a single raw material plate. An "assembly" is one in which multiple components are integrated together. Methods for integrating multiple components include a method using a known adhesive, a method using fastening parts, and the like. Fastening parts include bolts, nuts, screws, rivets, or pins. When the pellicle frame is an assembly, the multiple components may be made of different materials.

[0104] (3.2.2) Preparation method The method for preparing the frame with a hole is not particularly limited, and may be any known method.

[0105] (3.3) Second peeling process In the second peeling step, the substrate-attached CNT membrane is immersed in a liquid, and the CNT membrane peeled off from the hydrophilic substrate is floated on the liquid surface. The liquid is not particularly limited as long as it can float the CNT membrane. For example, the liquid may be water, and is preferably a liquid with an SP value of 35 or more. The method for immersing the substrate-attached CNT membrane in the liquid is not particularly limited, and may be any known method. For example, the substrate-attached CNT membrane may be immersed in water while being fixed with a jig.

[0106] (3.4) Second scooping process In a second scooping step, the CNT film floating on the liquid surface is scooped up with a frame with holes, and the CNT film closes one side of the through-holes, thereby producing a CNT free-standing film.

[0107] (4) Laminate A laminate according to the present disclosure includes a carbon nanotube film, the carbon nanotube film including a plurality of carbon nanotubes, and a nitrogen atom concentration of the carbon nanotube film being 1.0 at % or less.

[0108] The laminate of the present disclosure has the above-mentioned configuration, so that the carbon nanotube film is easily peeled off when immersed in a liquid. The nitrogen on the surface of the laminate on the side where the CNT film is formed (hereinafter also referred to as the "CNT film side") is derived from a cation containing a nitrogen atom, a cation containing a nitrogen atom, or a quaternary amine contained in the dispersion liquid or a neutralized salt.

[0109] The nitrogen atom concentration on the side of the CNT film is 1.0 at% or less. When the nitrogen atom concentration on the side of the CNT film is 1.0 at% or less, damage to the CNT film caused by strong alkali is prevented. From the viewpoint of making the upper surface of the CNT film more basic, the nitrogen atom concentration on the side of the CNT film is preferably 0.01 at% or more, more preferably 0.1 at% or more, even more preferably 0.5 at% or more, and particularly preferably 0.7 at% or more. The method for measuring the nitrogen atom concentration on the side surface of the CNT film was the same as that described in the Examples.

[0110] One method for adjusting the nitrogen atom concentration on the side surface of the CNT film to 1.0 at % or less is to spin coat a nitrogen-containing basic cationic material and then allow time for the material to react.

[0111] The laminate of the present disclosure can be suitably produced by the method for producing a substrate-attached carbon nanotube film of the present disclosure.

[0112] The laminate of the present disclosure may include a hydrophilic substrate, a CNT film formed on the hydrophilic substrate, and a neutralized salt attached to the CNT film.

[0113] (4.1) Hydrophilic substrate Examples of the hydrophilic substrate include the same as those exemplified as the hydrophilic substrate in the above-mentioned film formation process. Among them, the hydrophilic substrate is preferably a silicon substrate. The material of the silicon substrate is silicon. If the hydrophilic substrate is a silicon substrate, a clean substrate with a flat surface is easily available, so that a flat CNT film with less foreign matter can be easily obtained.

[0114] (4.2)CNT film Examples of the CNT film include the same CNT films as those exemplified in the drying step described above.

[0115] (4.3) Neutralizing salt The neutralized salt may be, for example, a mixture of an anion, such as polyacrylic acid, a quaternary amine compound, and a cation.

[0116] As a method for confirming whether or not neutralized salt is attached to the CNT film, a method using state analysis in XPS measurement can be mentioned.

[0117] The amount of the neutralized salt attached is not particularly limited, and is preferably 1 to 99 parts by mass, more preferably 2 to 30 parts by mass, and even more preferably 5 to 20 parts by mass, relative to the total amount of the CNT film. The amount of neutralized salt attached can also be measured by a depth profile method in XPS measurement. EXAMPLES

[0118] The present disclosure will be described in further detail below with reference to examples, but the invention of the present disclosure is not limited to these examples.

[0119] [1] Example 1 [1.1] Film formation process As the multiple CNTs, multiple single-walled CNTs (manufactured by Meijo Nano Carbon Co., Ltd., product name: "EC1.5-P", tube diameter: 1 nm to 3 nm, tube length: 100 nm or more) synthesized by the eDIPS method were prepared.

[0120] To 60 mg of CNTs, 70 g of isopropyl alcohol and 30 g of ethanol were added, and 50 mg of polyacrylic acid was added as an additive, and the mixture was stirred to obtain a suspension. A magnetic stirrer was used for the stirring process. The rotation speed was 1000 rpm (revolutions per minute), the temperature was 40°C, and the treatment time was 18 hours. The obtained suspension was subjected to ultrasonic dispersion treatment, and then centrifugal separation treatment. A probe-type homogenizer was used for the ultrasonic dispersion treatment. In the ultrasonic dispersion treatment, the output of the probe-type homogenizer was 40% of the maximum output, and the total treatment time was 60 minutes. A centrifuge was used for the centrifugal separation treatment. In the centrifugal separation treatment, the rotation speed was 23,000 rpm, and the treatment time was 96 minutes. The suspension was centrifuged and the supernatant was collected to obtain a CNT dispersion, which was acidic (pH<7).

[0121] A 12-inch silicon wafer (hereinafter referred to as "silicon substrate") was prepared. The CNT dispersion liquid was spin-coated onto the silicon substrate at a rotation speed of 600 rpm. As a result, an unneutralized CNT film having a diameter of 280 mm was formed on the silicon substrate.

[0122] [1.2] Cleaning process [1.2.1] Neutralization process 2-propanol and ethanol were mixed to obtain a mixed solvent. The mass ratio of the mixed solvent (2-propanol / ethanol) was 7 / 3 (70 mass% / 30 mass%). Tetrabutylammonium hydroxide:30 hydrate was dissolved in the mixed solvent so that the amount was 1 part by mass per 100 parts by mass of the total amount of the mixed solvent and tetrabutylammonium hydroxide:30 hydrate, to obtain a pre-treatment liquid.

[0123] The pretreatment liquid was dropped onto the unneutralized CNT film formed on the silicon substrate, and the unneutralized CNT film was contacted with the pretreatment liquid by spin coating at a rotation speed of 600 rpm. In other words, the unneutralized CNT film was neutralized. As a result, an unwashed CNT film formed on the silicon substrate was obtained. A neutralized salt of polyacrylic acid and tetrabutylammonium hydroxide was attached to the unwashed CNT film.

[0124] [1.2.2] Cleaning process As a cleaning solution, isopropyl alcohol was prepared. The cleaning solution was dropped onto the uncleaned CNT film formed on the silicon substrate, and the uncleaned CNT film was contacted with the cleaning solution by spin coating at a rotation speed of 600 rpm. In other words, the uncleaned CNT film was cleaned. As a result, a cleaned CNT film formed on the silicon substrate was obtained.

[0125] [1.3] Drying process The washed CNT film was removed from the surface of the CNT film and dried by spin rotation. This resulted in a CNT film formed on the silicon substrate. In other words, a laminate was obtained. The laminate includes a silicon substrate, a CNT film formed on the silicon substrate, and a neutralized salt attached to the CNT film.

[0126] [1.4] Separation process The laminate was immersed in a water bath. In the water, the CNT film peeled off from the silicon substrate. The silicon substrate was removed from the water. The CNT film floating on the surface of the water was picked up by a lifting frame (adherend), and the CNT film was transferred to the lifting frame. This resulted in a pellicle film made of a CNT film with a mesh structure.

[0127] [1.4] Evaluation [1.4.1] Nitrogen atom concentration in laminate The nitrogen atom concentration on the surface of the laminate on which the CNT film was formed was measured by X-ray photoelectron spectroscopy (XPS). In detail, the ratio (%) of the integrated intensity of the peak component derived from nitrogen atoms to the integrated intensity of the peak components of all components in the XPS narrow spectrum analyzed by the XPS analysis method described below was defined as the "nitrogen atom concentration". All components include the coating (e.g., CNT, dispersant, peeling pretreatment agent, etc.). For example, all components can be determined from the integrated intensity of the peak components appearing in the range of 0 eV to 1350 eV. The integrated intensity of the peak component derived from nitrogen atoms can be determined from the integrated intensity appearing in the range of 392 eV to 412 eV.

[0128] [1.4.1.1] XPS analysis method Device name: AXIS-NOVA (manufactured by Slates / Shimadzu Corporation) X-ray used: AlKα ray (1486.6eV) Electron energy range: -5eV~1350eV (binding energy) wide scan and narrow scan Raster area: 0.3mm x 0.7mm

[0129] [1.4.2] Adhesion In the above-mentioned neutralization process, the pretreatment liquid was dropped onto a silicon substrate and spin-coated at a rotation speed of 600 rpm. It was visually observed whether or not the unneutralized CNT film peeled off from the silicon substrate.

[0130] In the above-mentioned cleaning process, the cleaning solution was dropped onto the silicon substrate and spin-coated at a rotation speed of 600 rpm, and it was visually observed whether or not the uncleaned CNT film peeled off from the silicon substrate.

[0131] Based on the above observation results of the neutralization process and the cleaning process, the adhesion was evaluated according to the following evaluation criteria.

[0132] [1.4.2.1] Adhesion evaluation criteria A1: In the neutralization process, the unwashed CNT film did not peel off from the silicon substrate after completion of spin coating, and in the cleaning process, the washed CNT film did not peel off from the silicon substrate after completion of spin coating. B1: A part of the unwashed CNT film peeled off from the silicon substrate after completion of spin coating in the neutralization process, or a part of the washed CNT film peeled off from the silicon substrate after completion of spin coating in the cleaning process.

[0133] [1.4.3] Peelability The laminate was immersed in a water bath, and in the water, the CNT film was visually observed to see whether it peeled off from the silicon substrate. Based on the observation results, the peelability was evaluated according to the following evaluation criteria. In Comparative Example 1, Comparative Example 2, and Comparative Example 3, the CNT film peeled off during the neutralization treatment, so the peelability could not be evaluated. In Comparative Example 4, the CNT film floated off the substrate, so it was peeled off by spinning only to remove foreign matter attached to the edge, and cleaning treatment could not be performed, so the peelability could not be evaluated.

[0134] [1.4.3.1] Evaluation criteria for peelability A2: When the laminate was immersed in a water bath, the entire CNT film peeled off from the silicon substrate. B2: When the laminate was immersed in a water bath, all or part of the CNT film did not peel off from the silicon substrate.

[0135] [2] Examples 2 to 7 and Comparative Examples 1 to 6 A pellicle film made of a CNT film was obtained in the same manner as in Example 1, except that the conditions of the neutralization process and the cleaning process were changed to those shown in Table 1. The evaluation results are shown in Table 1. Cracks were generated in the CNT films of Comparative Examples 1 to 3.

[0136] [Table 1]

[0137] In Table 1, "IPA" refers to isopropyl alcohol. "EtOH" refers to ethanol. "MeOH" refers to methanol. "H2O" refers to water. "PEGMEA" refers to propylene glycol monomethyl ether acetate. "1% TBAOH" refers to a solution containing tetrabutylammonium hydroxide hydrate, the content of which is 1% by mass relative to the total amount of the solution. "1% TMAH" refers to an aqueous solution containing tetramethylammonium hydroxide, the content of which is 1% by mass relative to the total amount of the aqueous solution.

[0138] In Comparative Example 1 and Comparative Example 4 to Comparative Example 6, the manufacturing method of the substrate-attached CNT film did not include a cleaning step. Therefore, the adhesion of Comparative Example 1 and Comparative Example 4 was evaluated as "B1." The peelability of Comparative Example 5 to Comparative Example 6 was evaluated as "B2." In Comparative Example 2, the SP value of the cleaning solvent was 30 (MPa). 0.5 Therefore, the adhesion of Comparative Example 2 was evaluated as "B1." In Comparative Example 3, the SP value of the cleaning solvent was 22 (MPa). 0.5 Therefore, the peelability of Comparative Example 3 was evaluated as "B2." From the above, it was found that the methods for manufacturing substrate-mounted CNT films in Comparative Examples 1 to 6 are not "methods for manufacturing substrate-mounted carbon nanotube films that can produce substrate-mounted carbon nanotube films that suppress peeling of the film from the substrate during cleaning such as spin coating and that easily peel off from the substrate when immersed in liquid."

[0139] In Comparative Example 3, Comparative Example 5, and Comparative Example 6, the nitrogen atomic concentration of the CNT film of the laminate was not 1.0 at% or less. Therefore, the peelability of Comparative Example 3, Comparative Example 5, and Comparative Example 6 was evaluated as "B2." From this result, it was found that the laminates of Comparative Example 3, Comparative Example 5, and Comparative Example 6 are not "laminates in which the carbon nanotube film easily peels off when immersed in liquid."

[0140] The manufacturing method of the substrate-attached CNT film in Examples 1 to 7 included a film-forming step, a cleaning step, and a drying step. The SP value of the cleaning solution solvent was 22 (MPa). 0.5 ~30(MPa) 0.5 Therefore, in Examples 1 to 7, the evaluation results of adhesion were "A1", and the evaluation result of peelability was "A2". From the above, it was found that the methods for manufacturing substrate-mounted CNT films in Examples 1 to 7 are "methods for manufacturing substrate-mounted carbon nanotube films that can suppress peeling of the film from the substrate during cleaning such as spin coating, and can produce substrate-mounted carbon nanotube films that easily peel off from the substrate when immersed in liquid."

[0141] In Examples 1 to 7, the nitrogen atom concentration of the CNT film of the laminate was 1.0 at% or less. Therefore, the peelability of Examples 1 to 7 was evaluated as "A2." From this result, it was found that the laminates of Examples 1 to 7 were "laminates from which the carbon nanotube film easily peels off when immersed in liquid."

Claims

1. Applying a dispersion liquid in which a plurality of carbon nanotubes are dispersed onto a hydrophilic substrate to form an unwashed carbon nanotube film; contacting the unwashed carbon nanotube film with a cleaning solution to produce a washed carbon nanotube film; drying the washed carbon nanotube film to produce a carbon nanotube film; having the dispersion comprises a hydrophilic functional group; The cleaning solution comprises a cleaning solution solvent, The Hansen solubility parameter of the cleaning solution solvent is 22 (MPa) ０．５ ~30 (MPa) ０．５ This is a method for producing a carbon nanotube film attached to a substrate.

2. The hydrophilic functional group is a carboxylic acid (COO － 2. The method for producing a substrate-attached carbon nanotube film according to claim 1, wherein the carbon nanotube film comprises at least one group selected from the group consisting of a silanol group, a hydroxyl group, a sulfone group, an amino group and a silanol group.

3. In preparing the washed carbon nanotube film, the unwashed carbon nanotube film is contacted with a pretreatment liquid and then with the washing liquid; the pre-treatment liquid contains a pre-treatment liquid solvent, The Hansen solubility parameter of the pre-treatment liquid solvent is 35 (MPa) ０．５ is as follows: When the dispersion liquid is acidic, the pre-treatment liquid is basic; 2. The method for producing a substrate-attached carbon nanotube film according to claim 1, wherein when the dispersion liquid is basic, the pretreatment liquid is acidic.

4. The dispersion is acidic, The method for producing a substrate-attached carbon nanotube film according to claim 3 , wherein the pretreatment liquid is basic.

5. 4. The method for producing a substrate-attached carbon nanotube film according to claim 3, wherein the pre-treatment solution solvent comprises at least one selected from the group consisting of cyclopentanone, dimethylacetamide, 2-butanol, N-methyl-2-pyrrolidone, 1-butanol, isopropyl alcohol, N,N-dimethylformamide, 1-propanol, γ-butyrolactone, ethanol, and methanol.

6. In preparing the washed carbon nanotube film, 4. The method for producing a substrate-attached carbon nanotube film according to claim 3, further comprising spin-coating the pre-treatment liquid onto the uncleaned carbon nanotube film to bring the uncleaned carbon nanotube film into contact with the pre-treatment liquid, and then spin-coating the cleaning liquid onto the uncleaned carbon nanotube film to bring the uncleaned carbon nanotube film into contact with the cleaning liquid.

7. 2. The method for producing a substrate-attached carbon nanotube film according to claim 1, wherein the cleaning solution solvent comprises at least one selected from the group consisting of cyclopentanone, dimethylacetamide, 2-butanol, N-methyl-2-pyrrolidone, 1-butanol, isopropyl alcohol, N,N-dimethylformamide, 1-propanol, γ-butyrolactone, ethanol, and methanol.

8. 2. The method for producing a substrate-attached carbon nanotube film according to claim 1, wherein the dispersion liquid contains at least one selected from the group consisting of polyacrylic acid, a flavin derivative, sodium cholate, sodium deoxycholate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium polyacrylate, and an organic side chain flavin.

9. 2. The method for producing a substrate-attached carbon nanotube film according to claim 1, wherein the carbon nanotube film has a thickness of 100 nm or less.

10. A method for producing a carbon nanotube film on a substrate according to any one of claims 1 to 9 is provided; Providing a frame having a through hole; The carbon nanotube film is then immersed in a liquid to float the carbon nanotube film peeled off from the substrate on the liquid surface; scooping up the carbon nanotube film floating on the liquid surface with the frame to produce a free-standing carbon nanotube film in which the carbon nanotube film blocks one of the through-holes; The carbon nanotube film is then heated to a temperature of 300° C. for 30 minutes.

11. A carbon nanotube film is included. the carbon nanotube film includes a plurality of carbon nanotubes; The carbon nanotube film has a nitrogen atom concentration of 1.0 at % or less.

Images