JP5868751B2 - Method for producing silver nanowire dispersion - Google Patents

Description

  The present invention relates to a method for producing a metal nanowire dispersion, a metal nanowire dispersion, a conductive member formed using the metal nanowire dispersion, a touch panel using the conductive member, and a solar cell. The present invention relates to a technique capable of obtaining a conductive member having excellent transparency.

  Currently, ITO is widely used as a transparent conductive material for electrodes used in display devices such as liquid crystal displays, organic EL, touch panels, and solar cells. However, there is a tint due to the small amount of indium metal reserves, low transmittance in the long wavelength region, high temperature heat treatment is required to reduce resistance, and there is no bending resistance Therefore, there is a problem that design properties such as a manufacturing method and a product shape are limited.

  Under such circumstances, studies on conductive members using metal nanowires have been reported (Patent Document 1). This is excellent in terms of transparency, low resistance, and reduction in the amount of metal used, and has high bending resistance, so that it can be used as a member that can solve the problems of the ITO transparent conductive member described above. Is growing.

  Several methods are known as methods for producing the metal nanowires. For example, Patent Document 2 discloses a manufacturing method for producing a wire by reducing silver ions while heating in ethylene glycol. Patent Document 3 discloses a method for producing silver nanowires in which a silver complex is heated in a water solvent at a temperature not higher than the boiling point of the water solvent. Patent documents 4 and 5 disclose a production method for removing impurities by purifying metal nanowires synthesized in ethylene glycol by ultrafiltration. Patent Document 6 discloses a manufacturing method for extracting metal nanorods synthesized in an aqueous solvent into an organic solvent that is phase-separated from water, although it is not a metal nanowire.

US Patent Application Publication No. 2007/0074316 US Patent Application Publication No. 2008/0210052 JP 2009-242880 A JP 2006-118036 A International Publication No. 2009/107694 JP 2005-270957 A

  The method for producing metal nanowires and the method for producing conductive members using the metal nanowire dispersion liquid include water or compatibility with water from the viewpoint of handling ease of production equipment such as no need for explosion-proofing and environmental impact during production. It is desired to use an aqueous solvent mixed with the solvent to be used. However, when the metal nanowire dispersion liquid produced by the method using an aqueous solvent disclosed in Patent Document 3 is applied to the production of a transparent conductive member, there is a problem that the resistance value of the conductive film is high. Therefore, in order to produce a low-resistance conductive member, the amount of metal nanowires to be used has to be increased, resulting in a problem that transparency is lowered.

  Further, in order to remove impurities from the metal nanowires, the metal nanowire dispersion synthesized with an aqueous solvent was purified by the purification method disclosed in Patent Documents 4 and 5, and the obtained metal nanowire dispersion was obtained. The resistance value of the transparent conductive member produced using the liquid could not be reduced.

  Furthermore, although the method disclosed in Patent Document 6 synthesizes metal nanorods in an aqueous solvent, the dispersion medium is finally converted into a non-aqueous solvent that undergoes phase separation from water through a purification step. Therefore, in order to produce a conductive member using the obtained dispersion, it is necessary to cope with explosion-proof production equipment, and the environmental load during production is higher than when an aqueous solvent is used. Therefore, the present invention is not applicable to the problem to be solved.

  The present invention has been made in view of such circumstances, and a method for producing a metal nanowire dispersion capable of realizing transparency and conductivity, a metal nanowire dispersion, and a conductive member formed using the metal nanowire dispersion And it aims at providing the touch panel using the electroconductive member, and a solar cell.

  As a result of intensive studies on the characteristics of conductive members formed using metal nanowires synthesized in an aqueous solvent, the present inventors have obtained the following knowledge. On the surface of the metal nanowire synthesized in an aqueous solvent, the low molecular weight dispersant added at the time of synthesis forms micelles on the surface of the metal nanowire and adheres without spacing. It was found that when a conductive member was produced using metal nanowires in this state, the low molecular dispersant hindered contact between the metal nanowires, so that the surface resistance of the conductive member was increased. In addition, it was found that the low molecular dispersant was strongly adsorbed on the surface of the metal nanowires, and thus the low molecular dispersant could not be removed sufficiently even if purification was performed in that state.

  Therefore, as a result of continuing intensive studies, the inventors have obtained the following knowledge. When the low molecular dispersant is replaced with the polymer dispersant, the polymer dispersant covers the surface of the metal nanowire with an interval, and the surface of the metal nanowire is exposed. At this time, it was possible to efficiently replace the low molecular weight dispersant with the high molecular weight dispersant by using a remover that peels the low molecular weight dispersant. When a conductive member is made using metal nanowires in which a low molecular dispersant is replaced with a polymer dispersant, the contact points between the metal nanowires increase, so the surface resistance decreases, that is, the conductivity increases, and the metal nanowires The inventors have found that transparency is increased by reducing the amount, and have reached the present invention.

  According to one aspect of the present invention, a method for producing a metal nanowire dispersion includes an aqueous dispersion containing metal nanowires surface-modified with a low molecular dispersant, a polymer dispersant, and the low molecular dispersant as the metal nanowire. A release solution to be peeled off, and mixing the aqueous dispersion and the release solution in a state where the polymer dispersant is included in at least one of the aqueous dispersion and the release solution And a purification step of separating and removing the low molecular weight dispersant from the mixed solution prepared in the mixing step.

  According to this aspect, the low molecular dispersant adsorbed on the surface of the metal nanowire is peeled and replaced with the polymer dispersant. By using the obtained metal nanowire dispersion liquid, a conductive member having low resistance and high transparency can be obtained. Moreover, since the low molecular weight dispersant is peeled off from the surface of the metal nanowire, the low molecular weight dispersant can be easily separated and removed from the mixed solution prepared in the mixing step.

  Preferably, the mixing step includes flow-mixing the stripping solution and the aqueous dispersion.

  Preferably, the polymer dispersant is any one of flow mixing using a solution containing the polymer dispersant and batch mixing using the polymer dispersant or a solution containing the polymer dispersant. Is added to at least one of the aqueous dispersion and the stripping solution.

  Preferably, the flow mixing includes performing using a T-shaped channel.

  Preferably, the purification step includes performing the cross-flow filtration.

  According to another aspect of the present invention, the metal nanowire dispersion is produced by a method for producing a metal nanowire dispersion.

  Preferably, the metal nanowire is a silver nanowire.

  Preferably, the metal nanowire dispersion has a conductivity of 1 mS / m or less.

  According to another aspect of the present invention, the conductive member is manufactured using a dispersion of metal nanowires.

  According to another aspect of the present invention, the touch panel is manufactured using a conductive member.

  According to an aspect of the present invention, the solar cell is manufactured using a conductive member.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is low resistance, the manufacturing method of a metal nanowire dispersion liquid applicable to manufacture of a highly transparent electroconductive member can be provided.

Explanatory drawing which shows the outline of a flow mixing apparatus. Explanatory drawing which shows the outline of a T-shaped flow mixing apparatus. Explanatory drawing which shows the outline of a Y-shaped flow mixing apparatus. The disassembled perspective view which shows the outline of another flow mixing apparatus. The schematic block diagram of the manufacturing flow of the mixing process in this form. The schematic block diagram of the manufacturing flow of the multistage mixing process in this aspect. The schematic block diagram of a crossflow filtration apparatus.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. The present invention is described by the following preferred embodiments, but can be modified in many ways without departing from the scope of the present invention, and other embodiments than the present embodiment are utilized. be able to. Accordingly, all modifications within the scope of the present invention are included in the claims. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to”.

(Method for producing metal nanowire dispersion)
The method for producing a metal nanowire dispersion according to the present aspect includes (1) a dispersion containing metal nanowires that have been surface-modified with a low molecular dispersant synthesized in an aqueous solvent, a polymer dispersant, and the low molecular dispersion. A mixing step of mixing a stripping solution for stripping the agent from the metal nanowire in a state where the polymer dispersant is included in either the dispersion liquid or the stripping solution; and (2) produced by the mixing step. And a purification step of separating and removing the low molecular dispersant from the mixed liquid.

[Metal nanowires]
There is no restriction | limiting in particular about the shape of the said metal nanowire. It can be appropriately selected according to the purpose, and can take any shape such as a columnar shape, a rectangular parallelepiped shape, or a columnar shape with a polygonal cross section. Further, the minor axis length described later means an average minor axis length, the major axis length means an average major axis length, and the minor axis length and the major axis length of the metal nanowire are, for example, transmission It can be determined by observing a TEM image using a scanning electron microscope (TEM).

  The metal nanowire preferably has a short axis length of 1 nm to 50 nm, more preferably 10 nm to 30 nm, and particularly preferably 15 nm to 25 nm. When the short axis length of the metal nanowire exceeds 50 nm, the characteristics as a conductor are improved, but there is a problem that haze due to light scattering is very conspicuous and transparency is lost. When the short axis length of the metal nanowire is less than 1 nm, the transparency is improved, but there is a problem that the conductivity is likely to deteriorate due to oxidation.

  The metal nanowire preferably has a long axis length of 1 μm to 30 μm, more preferably 3 μm to 20 μm, and particularly preferably 5 μm to 10 μm. When the major axis length of the metal nanowire is less than 1 μm, when the conductor is produced by coating, the metal-to-metal contact is reduced, making it difficult to conduct, resulting in an increase in resistance. If the length of the long axis exceeds 30 μm, the metal nanowires may be easily entangled or the dispersion stability may be deteriorated.

  There is no restriction | limiting in particular as a metal which comprises the said metal nanowire, According to the objective, it can select suitably, For example, it consists of 4th period, 5th period, and 6th period of a long periodic table (IUPAC1991). At least one metal selected from the group is preferable, at least one metal selected from Group 2 to 14 is more preferable, Group 2, Group 8, Group 9, Group 10, Group 11, Group At least one metal selected from Group 12, Group 13, and Group 14 is more preferable, and it is particularly preferable to include as a main component.

  Specific examples of the metal include copper, silver, gold, platinum, palladium, nickel, tin, cobalt, rhodium, iridium, iron, ruthenium, osmium, manganese, molybdenum, tungsten, niobium, tantel, titanium, bismuth, and antimony. , Lead, or an alloy thereof. Among these, copper, silver, gold, platinum, palladium, nickel, tin, cobalt, rhodium, iridium or alloys thereof are preferable, palladium, copper, silver, gold, platinum, tin and alloys thereof are more preferable, silver Or the alloy containing silver is especially preferable.

  The content of silver nanowires in the metal nanowire is preferably 50% by mass or more, more preferably 80% by mass or more, and the metal nanowire is more preferably substantially a silver nanowire. Here, “substantially” means that metal atoms other than silver inevitably mixed are allowed.

[Aqueous solvent]
The aqueous solvent in this embodiment means water or a mixed medium of water and a water-soluble solvent. As an aqueous solvent, it is preferable to use water. In addition to water, the aqueous solvent is, for example, alcohols such as methanol, ethanol, propanol, isopropanol and butanol; ethers such as dioxane and tetrahydrofuran; ketones such as acetone; cyclic ethers such as tetrahydrofuran and dioxane; ethylene glycol Water-soluble solvents such as glycols such as propylene glycol can be contained up to 50% by mass.

[Low molecular dispersant]
The low molecular weight dispersant in this embodiment has functions of controlling the form of metal nanowires and preventing aggregation when reducing metal ions in an aqueous solvent to synthesize metal nanowires. The low molecular dispersant means a compound having a molecular weight of 1000 or less and containing at least one selected from the group of amino group-containing compounds, thiol group-containing compounds, sulfide group-containing compounds, amino acids or derivatives thereof, and peptide compounds. . Of these, quaternary ammonium salts are preferred.

[Quaternary ammonium salt]
The quaternary ammonium salt is composed of a cation moiety serving as a quaternary ammonium ion and an anion moiety serving as a counter ion, and is represented by the following chemical formula (Formula 1).

  R1, R2, R3, and R4 are preferably compounds consisting of any one of n = 1 to 24 among the substituents represented by -CnH (2n + 1). Moreover, the same substituent may be sufficient as the substituent of R1-R4, respectively, and a different substituent may be sufficient as it.

  Examples of the cation moiety that becomes the quaternary ammonium ion include decyltrimethylammonium, dodecyltrimethylammonium, cetyltrimethylammonium, stearyltrimethylammonium, decylethyldimethylammonium, dodecylethyldimethylammonium, cetylethyldimethylammonium, stearylethyldimethylammonium, Examples include decyldiethylmethylammonium, dodecyldiethylmethylammonium, cetyldiethylmethylammonium, stearyldiethylmethylammonium, decyltriethylammonium, dodecyltriethylammonium, cetyltriethylammonium, stearyltriethylammonium, tetrabutylammonium and the like.

Examples of the anion moiety serving as the counter ion include various halide ions such as bromide ion (Br ⁻ ) and chloride ion (Cl ⁻ ), hydroxy ion (OH ⁻ ), nitrate ion (NO ₃ ⁻ ), and phosphoric acid. Examples include ions (PO ₄ ³⁻ ), carbonate ions (CO ₃ ⁻ ), sulfate ions (SO ₄ ²⁻ ), and the like. The quaternary ammonium salts listed above can also be used in combination of two or more selected from each.

[Reducing agent]
The metal nanowire in this embodiment is synthesized by reducing metal ions in an aqueous solvent. There is no restriction | limiting in particular as a reducing agent used when synthesize | combining metal nanowire, It can select suitably from what is normally used. For example, borohydride metal salts such as sodium borohydride and potassium borohydride; lithium aluminum hydride, potassium aluminum hydride, cesium aluminum hydride, beryllium aluminum hydride, magnesium magnesium hydride, calcium aluminum hydride, etc. Aluminum hydride salt; sodium sulfite, hydrazine compound, dextrin, hydroquinone, hydroxylamine, citric acid or its salt, succinic acid or its salt, ascorbic acid or its salt, etc .; diethylaminoethanol, ethanolamine, propanolamine, triethanolamine, Alkanolamines such as dimethylaminopropanol; aliphatics such as propylamine, butylamine, dipropyleneamine, ethylenediamine, triethylenepentamine Minor; heterocyclic amines such as piperidine, pyrrolidine, N-methylpyrrolidine and morpholine; aromatic amines such as aniline, N-methylaniline, toluidine, anisidine and phenetidine; aralkyl such as benzylamine, xylenediamine and N-methylbenzylamine Amines; ethylene glycol, glutathione, organic acids (citric acid, malic acid, tartaric acid, etc.), reducing sugars (glucose, galactose, mannose, fructose, sucrose, maltose, raffinose, stachyose, etc.), sugar alcohols (sorbitol, etc.) Can be mentioned. Among these, reducing sugars and sugar alcohols as derivatives thereof are particularly preferable. Two or more of the reducing agents listed above can be used in combination. In addition, it is preferable to control the pH of the aqueous solvent in order to adjust the reducing power.

[PH buffer]
The pH buffer used for the purpose of controlling pH when synthesizing metal nanowires in the aqueous solvent is not particularly limited. Examples include ammonia, carbonic acid, boric acid, acetic acid, various amino acids such as alanine, arginine, asparagine, and glycine, and salts thereof. Two or more pH buffering agents listed above can be used in combination.

  The pH of the aqueous solvent is preferably 8.0 or more and 9.0 or less. More preferably, it is 8.2 or more and 8.6 or less. By setting the pH of the aqueous solvent in the above range, the production of spherical silver particles can be prevented, and many silver nanowires having a large aspect ratio can be produced. Although it is preferable to use a pH buffering agent in order to suppress pH fluctuation during the reaction, it is particularly preferable to use a pH buffering agent as long as the pH is kept constant with a base such as sodium hydroxide while monitoring the pH. Not required. If the pH variation is large, unintended metal nanoparticles are generated as described later, and therefore it is preferable to reduce the pH variation during synthesis.

[Metal ions]
In the synthesis of the metal nanowire of this embodiment, a solution containing metal ions is added to an aqueous solvent. As a form of the metal ion in the solution to be added, if it is water-soluble, for example, it may form a complex ion with a ligand such as ammonia, but it must exist as a free ion in an aqueous solvent. preferable. Moreover, it is preferable to make the metal ion addition solution acidic. There is no restriction | limiting in particular in the acid used for pH adjustment, For example, organic acids, such as an acetic acid other than nitric acid, a sulfuric acid, phosphoric acid, carbonic acid, can also be used. If the metal ion-added solution is not acidic, a reduction reaction occurs before the metal ion-added solution diffuses into the aqueous solvent, and is not consumed for the growth of metal nanowires due to the reaction in the local region where the metal ion concentration is high. In addition, spherical particles, cubic particles, and amorphous polycrystalline particles may be generated.

[Metal nanoparticles]
In the synthesis of the metal nanowire of this embodiment, it is preferable to supply spherical or decahedral metal nanoparticles having a particle diameter of 1 to 100 nm to an aqueous solvent prior to the reduction reaction of metal ions. Since the reduction reaction starts from the timing of pH increase, the metal nanoparticles may be supplied before the reduction reaction.

  By taking the method, the metal nanowire can be grown on the surface of the metal nanoparticle using the metal nanoparticle as a seed crystal. By using the metal nanoparticles as seed crystals, it is possible to produce metal nanowires having a uniform short axis length and a long axis length distribution.

  When metal nanowires are grown without the metal nanoparticles, unintended metal nanoparticles are generated in the aqueous solvent. These metal nanoparticles have a large variation in shape between the particles. Therefore, when metal nanowires grow using these metal nanoparticles as seed crystals, there is a problem that the metal nanowires are polydispersed and form unstable.

  By using spherical or decahedral metal nanoparticles having a particle diameter of 1 to 100 nm as seed crystals, it is possible to produce metal nanowires having excellent monodispersity and a stable shape. In addition, if the pH of the aqueous solvent during the synthesis of the metal nanowire is too high, unintended metal nanoparticles are likely to be generated in the aqueous solvent. Therefore, the pH of the aqueous solvent should be maintained within a certain range during the production of the metal nanowire. Is preferred.

[Polymer dispersant]
The polymer dispersant in this embodiment is one that adsorbs to the surface of the metal nanowire and prevents aggregation of the metal nanowire, and is particularly a dispersant that dissolves in both the aqueous solvent and the stripping solution during the synthesis of the metal nanowire. Can be used without limitation. From the viewpoint of ensuring conductivity when applied to a conductive member, a dispersant having a molecular weight of more than 1000 is preferable, a dispersant of 2000 or more is more preferable, and a dispersant of 10,000 or more is more preferable. On the other hand, if the molecular weight is too large, the metal nanowires may agglomerate because it may take time to adsorb to the metal nanowires when mixed with the stripping solution. Therefore, the molecular weight of the polymer dispersant is preferably 500,000 or less, more preferably 100,000 or less, and even more preferably 50,000 or less. Specific examples of the polymer dispersant include gelatin, polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), partial alkyl ester of polyacrylic acid, methylcellulose, hydroxypropylmethylcellulose, polyalkyleneamine and the like. Can do.

  The polymer dispersant may be added as it is to a liquid containing metal nanowires surface-modified with the low molecular dispersant, or may be added in a state dissolved in a solvent. The solvent for dissolving the polymer dispersant can be used without particular limitation as long as the polymer dispersant can be dissolved, but the metal nanowire aqueous dispersion to be mixed is also preferably a solvent that can disperse and agglomerate during mixing. From the viewpoint of avoiding this, it is preferable to use the same solvent as the liquid containing the metal nanowires to be mixed. The concentration at which the polymer dispersant is dissolved can be used without particular limitation as long as the dispersant is dissolved, but if the concentration is too high and the viscosity becomes high, the mixing time becomes long. For this reason, the metal nanowires may be aggregated. Therefore, it is preferable to adjust the viscosity of the solvent after dissolving the polymer dispersant to 1000 cP or less, more preferably 100 cP or less, and more preferably 10 cP or less. More preferably. Moreover, you may use the peeling liquid mentioned later as a solvent.

[Stripping solution]
The stripping solution for stripping the low molecular weight dispersant from the metal nanowire is not particularly limited as long as both the low molecular weight dispersant and the polymer dispersant are dissolved in the mixed solvent of the metal nanowire and the stripping solution. be able to. Among them, methanol, ethanol, 1-propanol, 2-propanol, and acetone are preferable, in which both the dispersant and the polymer dispersant have high solubility in the mixed solvent, and 1-propanol and 2-propanol having particularly high solubility are preferable. 1-propanol having higher solubility is more preferable.

[Mixing process]
Next, a mixing process of a liquid containing metal nanowires, a polymer dispersant, and a low molecular dispersant stripping liquid will be described. When adding a polymer dispersant to a liquid containing metal nanowires surface-modified with a low molecular dispersant, the polymer dispersant can be added as described above, or the polymer dispersant can be added in a solvent. It can also be added in a dissolved state.

  When adding in a state of being dissolved in a solvent, batch mixing (adding and mixing a solution in which a polymer dispersant is dissolved into a tank containing a metal nanowire whose surface is modified with a low molecular dispersant) , Flow mixing (mixing a liquid containing a metal nanowire and a liquid in which a polymer dispersant is dissolved at a constant flow rate in a pipe), or the like. Any method can be carried out, but it is preferable to carry out flow mixing from the viewpoint of suppressing the occurrence of aggregation due to entanglement of metal nanowires. The mixing ratio of the solution containing the polymer dispersant and the water solvent (polymer dispersion material solution / metal nanowire liquid) is not particularly limited as long as it does not cause aggregation of the metal nanowires. Since the concentration decreases and the total amount of the dispersion increases, it is preferably 5 or less, more preferably 1 or less, and even more preferably 0.5 or less. On the other hand, if the mixing ratio is too low, the weight ratio of metal / (metal + polymer dispersant) becomes high and aggregation of metal nanowires occurs, so the weight ratio of metal / (metal + polymer dispersant) is Conditions of 0.9 or less are preferred, 0.5 or less are more preferred, and 0.1 or less are even more preferred.

  After the above step, a metal nanowire is mixed by mixing a liquid mixture including a liquid containing a metal nanowire whose surface is modified with a low molecular dispersant and a polymer dispersant, and a peeling liquid for peeling the low molecular dispersant from the metal nanowire. The low molecular dispersant that modifies the surface of the substrate is peeled off and replaced with a polymer dispersant.

  Mixing of the mixture of the dispersion containing the metal nanowires surface-modified with the low molecular dispersant and the polymer dispersant and the stripping solution can be performed by batch mixing, flow mixing, or the like. Batch mixing means adding and mixing a mixture in a certain amount of stripping solution. Flow mixing means that the stripping solution and the mixed solution are continuously mixed at a constant flow rate by piping. Any method can be used for mixing in this embodiment. Among these, it is preferable to mix the stripping solution and the mixed solution by flow mixing from the viewpoint of suppressing the occurrence of aggregation due to the entanglement of the metal nanowires. By performing flow mixing, occurrence of aggregation of metal nanowires can be suppressed. The mixing ratio of the stripping solution to the mixed solution (peeling solution / mixed solution) is not particularly limited as long as the metal nanowires do not aggregate. However, if the mixing ratio is too high, the metal concentration decreases and the volume of the dispersion increases. Therefore, it is not preferable from the viewpoint of productivity. Therefore, 10 or less is preferable, 1 or less is more preferable, and 0.75 or less is still more preferable. On the other hand, if the mixing ratio is too low, the metal nanowires may aggregate due to insufficient detachment of the dispersant during particle formation. Therefore, 0.01 or more is preferable, 0.1 or more is more preferable, and 0.3 or more is still more preferable.

  By performing flow mixing of the mixed solution and the stripping solution, aggregation of metal nanowires in an aqueous solvent can be suppressed. Further, the amount of the stripping solution used can be reduced to about ½.

  Next, the manufacturing flow of the mixing process will be described. 5 and 6 are schematic explanatory diagrams of the manufacturing flow of the mixing step.

  FIG. 5 shows a case where a mixed solution containing a metal nanowire surface-modified with a low molecular dispersant and a polymer dispersant is mixed with a release solution of the low molecular dispersant, or the surface is modified with a low molecular dispersant. It is a schematic explanatory drawing of the manufacturing flow of the mixing process in the case of mixing the dispersion liquid containing a metal nanowire, and the low molecular dispersing agent peeling liquid containing a polymer dispersing agent. Here, a case where a mixed solution containing metal nanowires and a polymer dispersant and a stripping solution are mixed will be described as an example. However, a dispersion containing metal nanowires and a low molecular dispersant containing a polymer dispersant are stripped. The same can be done when mixing the liquid. A mixed liquid containing metal nanowires surface-modified with a low molecular dispersant and a polymer dispersant is stored in the first addition tank 201. Further, a stripping solution for stripping the low molecular dispersant from the metal nanowire is stored in the second addition tank 202. The liquid mixture is fed from the first addition tank 201 to the flow mixing device 221 by the first liquid feed pump 211. Further, the stripping solution is fed from the second addition tank 202 to the flow mixing device 221 by the second feeding pump 212. In the flow mixing device 221, the mixed solution and the stripping solution are mixed.

  The first liquid feeding pump 211 can be used without any limitation as long as it can feed a liquid containing metal nanowires. However, a pump capable of feeding liquid even at a relatively high pressure without destroying the metal nanowires. It is preferable to use it. The destruction of the metal nanowire refers to the breaking, breaking, entanglement, etc. of the wire. As the pump as described above, a Mono pump, a syringe pump, a plunger pump, and a diaphragm pump are desirable. From the viewpoint of production suitability, a Mono pump, a plunger pump, and a diaphragm pump capable of continuously feeding a large amount of liquid are desirable. The plunger pump is preferably a triple plunger pump from the viewpoint of flow rate stability.

  In the flow mixing device 221, the mixing ratio of the mixed liquid to be mixed and the stripping liquid is important. Therefore, it is preferable to use a pump that can continuously supply liquid at a relatively high pressure and less pulsation as the second liquid supply pump 212, for example, a triple plunger pump, a gear pump, a diaphragm pump, or a Mono pump. Is preferred.

  The low molecular weight dispersant and the high molecular weight dispersant are replaced in the flow mixing device 221. From the flow mixing device 221, the coarse dispersion liquid containing the metal nanowires surface-treated with the polymer dispersant is discharged and recovered by the recovery tank 203. The recovered metal nanowire crude dispersion is then sent to the purification step. Here, the metal nanowire coarse dispersion is a mixture of a liquid containing a metal nanowire whose surface is modified with a low molecular dispersant, a polymer dispersant, and the low molecular dispersant. Show.

  FIG. 6 shows a mixing process in a case where a dispersion containing metal nanowires surface-modified with a low molecular dispersant, a solution containing a polymer dispersant, and a stripping solution for peeling the low molecular dispersant are mixed in multiple stages. It is a schematic explanatory drawing of a manufacturing flow. A dispersion containing metal nanowires surface-modified with a low molecular dispersant is stored in the first addition tank 301. In addition, a solution containing the polymer dispersant is stored in the second addition tank 302. Further, a stripping solution for stripping the low molecular dispersant is stored in the third addition tank 303. The liquid mixture is fed from the first addition tank 301 to the first flow mixing device 321 by the first liquid feed pump 311. In addition, the polymer dispersant solution is fed from the second addition tank 302 to the first flow mixing device 321 by the second liquid feeding pump 212. In the first flow mixing device 321, the dispersion containing the metal nanowires and the polymer dispersant solution are mixed.

  The first liquid feed pump 311 can be used without particular limitation as long as a liquid containing metal nanowires can be fed. However, a pump capable of feeding liquid even at a relatively high pressure without destroying the metal nanowires. It is preferable to use it. The destruction of the metal nanowire refers to the breaking, breaking, entanglement, etc. of the wire. As the pump as described above, a Mono pump, a syringe pump, a plunger pump, and a diaphragm pump are desirable. From the viewpoint of production suitability, a Mono pump, a plunger pump, and a diaphragm pump capable of continuously feeding a large amount of liquid are desirable. The plunger pump is preferably a triple plunger pump from the viewpoint of flow rate stability.

  In the first flow mixing device 321, the mixing ratio of the mixed liquid to be mixed and the polymer dispersant solution is important. Therefore, it is preferable to use a pump that can continuously supply liquid with a relatively high pressure and less pulsation as the second liquid supply pump 312, for example, a triple plunger pump, a gear pump, a diaphragm pump, or a Mono pump. Is preferred.

  The mixed solution of the metal nanowire liquid and the polymer dispersant solution mixed by the first flow mixing device 221 is sent to the second flow mixing device 222. In addition, the third liquid feed pump 213 feeds the release liquid of the low molecular dispersant from the third addition tank 203 to the second flow mixing device 222. In the second flow mixing device 222, the mixed solution and the stripping solution are mixed.

  In the second flow mixing device 322, the low molecular dispersant and the high molecular dispersant are replaced. From the second flow mixing device 322, the coarse dispersion liquid containing the metal nanowires surface-treated with the polymer dispersant is discharged and recovered by the recovery tank 304. The recovered metal nanowire crude dispersion is then sent to the purification step. As described above, the metal nanowire rough dispersion is a mixture of a liquid containing metal nanowires surface-modified with a low molecular dispersant, a polymer dispersant, and the low molecular dispersant. It shows that.

[Flow mixing equipment]
A turbulent flow mixing device for performing flow mixing will be described. FIG. 1 is an example of a flow mixing device applied to mix at least two fluids. As shown in FIG. 1, the flow mixing apparatus 10 is divided into two in one supply channel 12 for supplying the first fluid A so that the first fluid A can be divided into two. The divided supply channels 12A and 12B, the one non-divided supply channel 14 that supplies the second fluid B, and the flow that performs the reaction and flow of the first fluid A and the second fluid B The channel 16 is formed so as to communicate with one mixing region 18. Further, the divided supply channels 12A and 12B, the supply channel 14, and the channel 16 are arranged at equal intervals of 90 ° around the mixing region 18 in substantially the same plane. That is, the central axes (one-dot chain lines) of the flow paths 12A, 12B, 14, and 16 intersect in a cross shape (intersection angle α = 90 °) in the mixed region 18. In FIG. 1, only the first fluid A supply channel 12 is divided, but the second fluid B supply channel 14 may also be divided into a plurality. Further, the crossing angle α of the flow paths 12A, 12B, 14, and 16 arranged around the mixing region 18 is not limited to 90 ° and can be set as appropriate. In addition, the number of divisions of the supply channels 12 and 14 is not particularly limited, but if the number is too large, the structure of the flow mixing device 10 becomes complicated, so 2 to 10 is preferable, and 2 to 5 is more preferable. preferable.

  FIG. 2 is a conceptual diagram showing the structure of one embodiment of the T-shaped flow mixing device 60. The T-shaped flow mixing device 60 in FIG. 2A includes a supply channel 62 that supplies the first fluid A, a supply channel 66 that supplies the second fluid B, and the first fluid A. The flow path 68 that performs the reaction with the second fluid B is configured to communicate with one mixing region 64.

  The volume of the mixing region of the T-shaped flow mixing device 60 can be obtained as follows. FIG. 2B is a conceptual diagram showing a mixing region of the T-shaped flow mixing device 60. In the flow mixing device 60, the supply channel 62, the supply channel 66, and the channel 68 have the same diameter. In this case, from the point or line where the supply flow path 62 and the supply flow path 66 intersect (a point when the flow path is cylindrical, a line when the flow path is rectangular), the supply flow path 62 and the supply flow path 66 are A region where the extension line intersects the flow path 68 or a hatched area connecting the lines is the mixed region 64.

  FIG. 3 is a conceptual diagram showing a structure of one aspect of the Y-shaped flow mixing device 70.

  The Y-shaped flow mixing device 70 in FIG. 3A includes a supply channel 72 that supplies the first fluid A, a supply channel 76 that supplies the second fluid B, and the first fluid A. A flow path 78 that reacts with the second fluid B is configured to communicate with one mixing region 74.

  With respect to the Y-shaped flow mixing device 70, the volume of the mixing region can be determined as follows.

  FIG. 3B is a conceptual diagram showing a mixing region of the Y-shaped flow mixing device 70. In this flow mixing apparatus 70, the supply flow path 72, the supply flow path 76, and the flow path 78 have the same diameter. In this case, from the point or line where the supply flow path 72 and the supply flow path 76 intersect (a point when the flow path is cylindrical, a line when the flow path is rectangular), the supply flow path 72 and the supply flow path 76 are A region where the extension line intersects with the flow path 78 or a hatched region connecting the lines is a mixed region 74.

  FIG. 4 is a perspective view showing an example of another turbulent flow mixing device. In the illustrated embodiment, a perspective view of the three parts constituting the flow mixing device 100 is shown. The mixing device is constituted by a supply element 132, a merging element 104, and a discharge element 106 each having a cylindrical shape. When configuring the flow mixing device, these elements are assembled and assembled together so as to form a columnar shape. For this assembly, for example, bores (or holes, not shown) penetrating the cylinder may be provided at equal intervals in the periphery of each element, and these elements may be fastened together with bolts / nuts.

  On the surface of the supply element 132 facing the confluence element 104, annular channels 108 and 110 having a rectangular cross section are formed concentrically. In the illustrated embodiment, bores 134 and 114 are formed through feed element 132 in its thickness (or height) direction to the respective annular channels.

  The joining element 104 is formed with a bore 116 penetrating in the thickness direction. The bore 116 is configured such that when the elements are fastened to form a mixing device, the end 120 of the bore 116 located in the face of the merging element opposite the feed element opens into the annular channel 108. In the illustrated embodiment, four bores 116 are formed and are arranged at equal intervals in the circumferential direction of the annular channel 108.

  A bore 118 is formed through the confluence element 104 in the same manner as the bore 116. As with the bore 116, the bore 118 is also formed to open to the annular channel 110. In the illustrated embodiment, the bores 118 are also arranged at equal intervals in the circumferential direction of the annular channel 110, and the bores 116 and the bores 118 are arranged alternately.

  Channels 124 and 126 are formed on the surface 122 of the confluence element 104 facing the discharge element 106. One end of this channel 124 or 126 is the opening of the bore 116 or 118, and the other end is the center 128 of the face 122, and all channels extend from the bore toward this center 128 and are centered. Have joined. The cross section of the channel may be rectangular, for example.

  The discharge element 106 is formed with a bore 130 that passes through the center thereof and penetrates in the thickness direction. Therefore, this bore opens at the center 128 of the confluence element 104 at one end and opens outside the mixing device at the other end.

  As can be readily appreciated, the annular channels 108 and 110 correspond to the feed channels of the mixing device, and the fluids A and B supplied from the outside of the mixing device at the ends of the bores 134 and 114 are the bores 134 and 110, respectively. It flows into the annular channels 108 and 110 via 114.

  The annular channel 108 and the bore 116 communicate with each other, and the fluid A flowing into the annular channel 108 enters the channel 124 through the bore 116. In addition, the annular channel 110 and the bore 118 communicate with each other, and the fluid B flowing into the annular channel 110 enters the channel 126 via the bore 118. As can be seen, fluids A and B are divided into four in the merge region and flow into channels 124 and 126, respectively, and then flow toward center 128.

  As can be readily appreciated, the bore 116 or 118 and the channel 124 or 126 correspond to a subchannel of the flow mixing device, and the center 128 of the confluence element corresponds to the confluence region. The central axis of the channel 124 and the central axis of the channel 126 intersect at the center 128. The joined fluid is discharged as a stream C to the outside of the mixing device via the bore 130. Thus, the bore 130 corresponds to the discharge channel of the mixing device of the present invention.

  It should be noted that the flow mixing apparatus shown in the figure, particularly each element, is manufactured by a semiconductor processing technology, particularly etching (eg, photolithography etching) processing, ultra-fine electrical discharge processing, photo molding method, mirror finishing processing technology, diffusion bonding technology, etc. A machining technique can be used, and a machining technique using a general-purpose lathe or drilling machine can also be used, which can be easily manufactured by those skilled in the art.

  The material used for the flow mixing device is not particularly limited as long as it is a material to which the above-described processing technique can be applied and is not affected by the fluid to be joined. Specifically, a metal material (iron, aluminum, stainless steel, titanium, various alloys, etc.), a resin material (fluorine resin, acrylic resin, etc.), glass (silicon, quartz, etc.) can be used.

[Purification process]
The purification step of the metal nanowire crude dispersion in this embodiment is not particularly limited as long as the salt used during the synthesis of the metal nanowire can be removed, and more preferably, the dispersant during the synthesis of the metal nanowire can also be removed. It is more preferable if the excess of the polymer dispersing agent can be removed. As a means for purification, centrifugation, centrifugal filtration, cross flow filtration, solvent extraction, electrodialysis and the like can be freely selected. Among them, cross-flow filtration, solvent extraction, and electrodialysis that can be performed without increasing the metal concentration more than necessary to maintain the dispersibility of the metal nanowires are preferred, and polymer components can also be washed. Cross flow filtration with a wide selection of final solvents is more preferable.

  FIG. 7 is a schematic configuration diagram of the crossflow filtration device. The cross-flow filtration apparatus includes at least a tank in which a metal nanowire coarse dispersion to be purified is stored, a filter that separates the metal nanowire coarse dispersion in the tank into a filtrate and a concentrated liquid, and a metal nanowire coarse in the tank. And a pump for feeding the dispersion liquid. Further, a heat exchanger may be provided for controlling the temperature of the liquid circulating in the apparatus. Furthermore, in order to grasp the filtration conditions more accurately, a pressure gauge may be provided on the upstream side of the filter and between the filter and the heat exchanger, respectively.

  The material of the filter is not particularly limited, and a hollow fiber membrane of a polymer member selected from cellulose, polyether sulfonic acid type, PTFE, etc. can be used, or a porous ceramic. A membrane can also be used.

  The pore size of the filter can be freely selected without particular limitation as long as the salt can be washed, and is preferably a size that can also remove the low molecular dispersant during the synthesis of the metal nanowire, and is added in the mixing step. More preferably, it is a size that can remove the excess of the polymer dispersant, and a size that can remove by-product particles other than the wire shape generated in the metal nanowire synthesis step (hereinafter referred to as noise particles) If it is more preferable. Specifically, the pore size is preferably 40 angstroms or more, more preferably 100 angstroms or more, and even more preferably 500 angstroms or more. Further, if the pore size is too large, the metal nanowires may be clogged and aggregated, so the pore size is preferably 5 μm or less, more preferably 1 μm or less, and even more preferably 0.25 μm or less.

  The purification process by crossflow filtration will be described. A metal nanowire coarse dispersion to be purified is put into a tank, a liquid feed pump is operated, and the inside of the apparatus is circulated. When the metal nanowire coarse dispersion passes through the filter, a part of the solvent is discharged out of the filter as a filtrate. Therefore, the metal nanowire coarse dispersion is concentrated more than before the filter and returns to the tank. The metal nanowire coarse dispersion is concentrated by repeating the above-described steps while appropriately supplying an unpurified metal nanowire coarse dispersion into the tank.

  After the concentration of the metal nanowire crude dispersion is completed, a cleaning solvent is introduced into the tank, and the concentrated metal nanowire crude dispersion is cleaned. By repeatedly discharging the filtrate from the filter while appropriately supplying the cleaning solvent, the metal nanowire coarse dispersion and the solvent replacement can be performed while suppressing fluctuations in the concentration of the metal nanowires.

  In the purification step in this embodiment, the filtration rate can be adjusted by applying pressure to the filter unit as necessary. The average pressure above and below this filter is defined as the filtration pressure. If the filtration pressure is too high, the solid content deposited on the filter is compressed, and even if the solid content is removed from the filter surface by backwashing to be described later, it may not be redispersed. Therefore, the filtration pressure is preferably 0.5 MPa or less, 0.4 MPa or less is more preferable, and 0.2 MPa or less is still more preferable. On the other hand, if the filtration pressure is too low, the filtration flow rate becomes low and the process time becomes long, so 0.01 MPa or more is preferable, 0.02 MPa or more is preferable, and 0.03 MPa or more is more preferable.

  In the purification step in this embodiment, it is desirable to periodically perform backwashing during the concentration and washing in order to suppress a reduction in filtration efficiency due to the accumulation of solid content on the filter. Backwashing is an operation of pushing the filtrate back from the filter surface in contact with the filtrate to the surface in contact with the dispersion. In order to push the filtrate back, for example, a gas such as air may be used to pressurize the filtrate in the filtrate flow path in the direction opposite to the filtrate discharge direction. When the gas is used to push back the filtrate, the magnitude of the pressure to push back the filtrate is defined by the difference between the filtration pressure and the gas pressure for pushing back the filtrate, and this is the backwash pressure. The backwash pressure is not particularly limited as long as the solid content accumulated on the filter can be removed from the filter surface. However, if the pressure is too low, the solid content accumulated on the filter cannot be removed. Preferably, it is 0.2 MPa or more, more preferably 0.3 MPa or more. In addition, if the pressure is too high, the gas used for pushing back may be mixed in the dispersion, and the flow in the circulation channel may be disturbed, preferably 10 MPa or less, and preferably 5 MPa or less. More preferred is 3 MPa or less. Further, the interval for performing the backwashing is not particularly limited as long as the solid content accumulated on the filter surface can be removed. However, if the interval is too wide, the solid content cannot be removed from the filter surface. Minute intervals or less are preferred, 15 minute intervals or less are more preferred, and 10 minutes or less are even more preferred. In addition, since filtration is not performed during backwashing, if the backwashing interval is too short, the process time will be longer, so 15 seconds or more is preferable, 1 minute or more is more preferable, 3 minutes The above is more preferable.

  In the said refinement | purification process, after concentrating the rough dispersion liquid of metal nanowire, the refinement | purification of a dispersion liquid can be implemented, without raising a metal concentration excessively by adding a washing | cleaning liquid. As the cleaning liquid, any metal nanowire that does not aggregate can be used without particular limitation. In particular, it is preferably a cleaning solution in which the salt to be removed, the low molecular dispersant during the synthesis of the metal nanowires, and the excess polymer dispersant added in the mixing step are dissolved.

  The end timing of purification in the purification step can be determined without particular limitation. However, if the purification is not sufficient, the cause of performance change of the completed metal nanowire dispersion over time and the salt remaining in the dispersion may be a cause of deterioration in durability when the conductive member is produced. Therefore, it is preferable to wash until the electrical conductivity of the metal nanowire dispersion becomes 10 mS / m or less, more preferably 5 mS / m or less, and even more preferably 1 mS / m or less.

[Metal nanowire dispersion after purification process]
The metal nanowire dispersion liquid after the purification step contains metal nanowires produced by the above-described production method in a dispersion solvent.

  The metal nanowire dispersion liquid after the purification step in this embodiment contains metal nanowires produced by the above-described production method in a dispersion solvent.

  0.1 mass%-99 mass% are preferable, and, as for metal nanowire content in the metal nanowire dispersion liquid after the said refinement | purification process, 0.3 mass%-10 mass% are more preferable. When the content is less than 0.1% by mass, the load in the drying process is great during production, and when it exceeds 99% by mass, particle aggregation may easily occur.

  As a dispersion solvent for the metal nanowire dispersion liquid, water and organic solvents can be used without particular limitation as long as the dispersant can be dissolved therein. As the organic solvent, for example, an alcohol compound having a boiling point of 50 ° C to 250 ° C, more preferably 55 ° C to 200 ° C is preferably used. By using such an alcohol compound in combination, it is possible to improve the coating in the coating process and reduce the drying load.

  The alcohol compound is not particularly limited and may be appropriately selected depending on the intended purpose. For example, methanol, ethanol, 1-propanol, isopropanol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol 200, polyethylene glycol 300 Glycerin, propylene glycol, dipropylene glycol, 1,3-propanediol, 1,2-butanediol, 1,4-butanediol, 1,5-pentanediol, 1-ethoxy-2-propanol, ethanolamine, diethanolamine , 2- (2-aminoethoxy) ethanol, 2-dimethylaminoisopropanol, and the like. These may be used individually by 1 type and may use 2 or more types together. Among these, ethanol, 1-propanol, and isopropanol are particularly preferable.

  The metal nanowire dispersion liquid in this embodiment preferably contains as little inorganic ions as possible, such as alkali metal ions, alkaline earth metal ions, and halide ions. If these ions remain, the durability may be deteriorated when the conductive member is produced.

  If necessary, the metal nanowire dispersion contains various additives such as surfactants, polymerizable compounds, antioxidants, sulfidation inhibitors, corrosion inhibitors, viscosity modifiers, preservatives, and the like. be able to.

  There is no restriction | limiting in particular in the thing to be used as said corrosion inhibitor, Although it can select suitably according to the objective, Among these, azoles are suitable. Examples of the azoles include benzotriazole, tolyltriazole, mercaptobenzothiazole, mercaptobenzotriazole, mercaptobenzotetrazole, (2-benzothiazolylthio) acetic acid, 3- (2-benzothiazolylthio) propionic acid, and these And at least one selected from alkali metal salts, ammonium salts, and amine salts. By containing the corrosion inhibitor, a further excellent rust prevention effect can be exhibited. As a method for adding the corrosion inhibitor, it is directly added to the metal nanowire aqueous dispersion in a state dissolved in powder or a suitable solvent, or added in powder, or after preparing a conductive member described later, this is added to the corrosion inhibitor bath. It can be given by immersing in.

  The metal nanowire dispersion liquid of this embodiment can also be preferably used for water-based inks for inkjet printers and water-based inks for dispensers. In an image forming application using an inkjet printer, examples of the substrate on which the metal nanowire dispersion liquid is coated include paper, coated paper, and a PET film having a surface coated with a hydrophilic polymer.

[Conductive member]
The conductive member using the metal nanowire dispersion liquid of this embodiment has a conductive layer formed from the metal nanowire dispersion liquid. The conductive member is manufactured by coating a metal nanowire dispersion on a substrate and drying. Below, a conductive member is demonstrated in detail through description of the manufacturing method of a conductive member.

  There is no restriction | limiting in particular as a support body which coats the metal nanowire dispersion liquid of this aspect, According to the objective, it can select suitably. For example, the following are mentioned as a support for transparent conductive members. Among these, polymer films are preferable from the viewpoints of production suitability, lightness, flexibility, optical properties (polarization properties), and the like, and PET, TAC, and PEN films are particularly preferable.

  (1) Quartz glass, alkali-free glass, crystallized transparent glass, Pyrex (registered trademark) glass, glass such as sapphire.

  (2) Acrylic resins such as polycarbonate and polymethyl methacrylate, vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymers, polyarylate, polysulfone, polyethersulfone, polyimide, PET, TAC, PEN, fluororesin, Thermoplastic resins such as phenoxy resin, polyolefin resin, nylon, styrene resin, ABS resin.

  (3) Thermosetting resin such as epoxy resin.

  As a material used for the support, a plurality of members may be used in combination as necessary. Depending on the application, it can be appropriately selected from these support materials to form a flexible support such as a film or a rigid support.

  The shape of the support may be any shape such as a disk shape, a card shape, or a sheet shape. Moreover, the thing laminated | stacked three-dimensionally may be used. Further, the substrate may have fine pores and fine grooves having an aspect ratio of 1 or more at a place where printed wiring is performed, and the metal nanowire dispersion of the present invention may be discharged into these by an ink jet printer or a dispenser. it can.

When providing the conductive layer using the metal nanowire dispersion liquid of the present invention, the support is hydrophilized on one or both sides for the purpose of improving the adhesion of the functional layer and improving the wettability of the coating liquid. It is more preferable to perform a pretreatment such as uneven processing. Examples of the pretreatment include corona discharge treatment, glow discharge treatment, plasma treatment, atmospheric pressure plasma treatment, flame treatment, hot air treatment, ozone / ultraviolet irradiation treatment, chromic acid treatment (wet), and saponification treatment (wet). However, corona discharge treatment and plasma treatment (vacuum glow discharge and atmospheric pressure glow discharge treatment) are particularly preferred.
[Plasma treatment]
Examples of the plasma treatment include vacuum glow discharge and atmospheric pressure glow discharge, and other methods include flame plasma treatment and the like. For example, methods described in JP-A-6-123062, JP-A-11-293011, JP-A-11-5857 and the like can be used.

  In the plasma treatment, a film to be imparted with hydrophilicity is disposed between opposing electrodes, a plasma-exciting gas is introduced into the apparatus, and a high-frequency voltage is applied between the electrodes, whereby the gas is treated. Surface treatment can be performed by exciting the plasma and causing glow discharge between the electrodes. Among these, those using atmospheric pressure glow discharge are preferably used.

  The plasma-exciting gas is not particularly limited, but is preferably chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof, argon, What added the reactive gas which can provide polar functional groups, such as a carboxyl group, a hydroxyl group, and a carbonyl group, to the surface of a plastic film to inert gas, such as neon, is preferable. As the reactive gas, in addition to gases such as hydrogen, oxygen, and nitrogen, water vapor, ammonia, and other low-boiling organic compounds such as lower hydrocarbons and ketones can be used as necessary. From this viewpoint, gases such as hydrogen, oxygen, carbon dioxide, nitrogen, and water vapor are preferable. In the case of using water vapor, a gas obtained by bubbling other gas through water can be used. Alternatively, water vapor may be mixed.

  The frequency of the high-frequency voltage is preferably 1 kHz to 100 kHz, more preferably 1 kHz to 10 kHz.

  The plasma treatment by glow discharge includes a method of performing this under vacuum and a method of performing this under atmospheric pressure.

  In the vacuum plasma discharge treatment by glow discharge, it is necessary to introduce the reactive gas so as to keep the atmosphere in the range of 0.005 to 20 torr in order to cause discharge effectively. In order to increase the processing speed, it is preferable to adopt a high output condition on the high pressure side as much as possible. However, if the electric field strength is increased too much, the support may be damaged.

  In the case of atmospheric pressure glow discharge in which plasma discharge is performed in the vicinity of atmospheric pressure, an inert gas such as helium or argon is necessary to cause stable discharge, and more than 60% of the plasma exciting gas is inactive. Unless it is an active gas, stable discharge does not occur. However, if there is too much inert gas and the proportion of the reactive gas is small, the processing speed decreases. Even if the electric field strength is increased too much, the support may be damaged.

Even when plasma treatment is performed in the vicinity of atmospheric pressure, when generating plasma by pulsed electrolysis, the inert gas is not necessarily required, and the reaction gas concentration can be increased and the reaction rate can be increased. I can do it.
[Corona discharge treatment]
The corona discharge treatment may be performed by any conventionally known method, for example, Japanese Patent Publication Nos. 48-5043, 47-51905, JP-A 47-28067, 49-83767, 51-41770. This can be achieved by the method disclosed in Japanese Patent Laid-Open No. 51-131576. Various commercially available corona treatment machines can be used as the treatment machine. For example, a corona treatment machine having a multi-knife electrode manufactured by SOFTAL (Sophthal) is composed of a large number of electrodes, and the film is heated by sending air between the electrodes. This is useful because it can prevent or remove small molecules from the film surface. Moreover, in order to avoid the spark between an electrode and a conductive layer with respect to the surface which has not provided the conductive layer of the base material which provided the conductive layer on one side, as a discharge electrode, it is a dielectric covering electrode. (Ceramic electrode, quartz electrode, etc.) is preferably subjected to corona treatment using a metal roll such as stainless steel as the counter electrode.

  The corona treatment conditions vary depending on the type of support used, the type of coating matrix, the type of corona treatment machine used, etc., but the corona surface treatment has an irradiation energy of 0.1 J / m 2 or more and 10 J / m. It is preferable to carry out within the range of m2 or less, and more preferably 0.5 J / m2 or more and 5 J / m2 or less.

  When the support surface is hydrophilized by performing these surface treatments, the contact angle of the support surface with respect to water is preferably 0 ° to 40 °, more preferably 0 ° 20 °, and most preferably 0. It is preferable that the angle is in the range of 10 °.

  In the present embodiment, after forming the conductive member, it can be preferably passed through a corrosion inhibitor bath, whereby a further excellent corrosion prevention effect can be obtained.

The method for forming the metal nanowire dispersion liquid of this embodiment on the substrate can be performed by a general coating method, and is not particularly limited and can be appropriately selected depending on the purpose. For example, a roll coating method, a bar Examples thereof include a coating method, a dip coating method, a spin coating method, a casting method, a die coating method, a blade coating method, a bar coating method, a gravure coating method, a curtain coating method, a spray coating method, and a doctor coating method.
(Use)
Examples of the conductive member using the metal nanowire dispersion of this embodiment include touch panels, antistatics for displays, electromagnetic wave shields, electrodes for organic or inorganic EL displays, electrodes for flexible displays / antistatics, electrodes for solar cells, and electronic paper. It is widely applied to various devices such as.

  Hereinafter, the present invention will be described in more detail with reference to examples of the present invention. However, the present invention is not limited to these examples.

<Average minor axis length (average diameter) and average major axis length of metal nanowires>
Measure the short axis length (diameter) and long axis length of 300 metal nanowires randomly selected from metal nanowires that are enlarged and observed using a transmission electron microscope (TEM; manufactured by JEOL Ltd., JEM-2000FX) And the average minor-axis length (average diameter) and average major-axis length of metal nanowire were calculated | required from the average value.

<Coefficient of variation of short axis length (diameter) of metal nanowires>
The short axis length (diameter) of 300 nanowires randomly selected from the electron microscope (TEM) image was measured, and the standard deviation and average value of the 300 nanowires were calculated.

<Ratio of silver nanowires with an aspect ratio of 10 or more>
Using a transmission electron microscope (TEM; manufactured by JEOL Ltd., JEM-2000FX), 300 minor axis lengths of the silver nanowires were observed, and the amount of silver transmitted through the filter paper was measured. The minor axis length was 50 nm or less. The silver nanowires having a major axis length of 5 μm or more were determined as the ratio (%) of silver nanowires having an aspect ratio of 10 or more. The silver nanowires were separated when determining the ratio of silver nanowires using a membrane filter (Millipore, FALP 02500, pore size: 1.0 μm).

(Preparation Examples 1 and 2: Synthesis of silver nanowires)
(Preparation Example 1)
-Preparation of silver nanowire dispersion (1)-
The following additive solutions A, B, C, and D were prepared in advance.

[Additive liquid A]
Stearyltrimethylammonium chloride 60 mg, stearyltrimethylammonium hydroxide 10% aqueous solution 6.0 g, and glucose 2.0 g were dissolved in distilled water 120.0 g to obtain reaction solution A-1. Furthermore, 70 mg of silver nitrate powder was dissolved in 2.0 g of distilled water to obtain an aqueous silver nitrate solution A-1. The aqueous solution of silver nitrate A-1 was added while vigorously stirring the reaction solution A-1 at 25 ° C. After the addition of the aqueous silver nitrate solution A-1, the mixture was vigorously stirred for 180 minutes to obtain additive solution A.

[Additive liquid B]
42.0 g of silver nitrate powder was dissolved in 958 g of distilled water to obtain additive solution B.

[Additive liquid C]
75 g of 25% aqueous ammonia was mixed with 925 g of distilled water to obtain additive C.

[Additive solution D]
400 g of polyvinylpyrrolidone (PVP) (K30) was dissolved in 1.6 kg of distilled water to obtain an additive solution D.

  Next, a silver nanowire dispersion liquid (1) was prepared as follows. 1.30 g of stearyltrimethylammonium bromide powder, 33.1 g of sodium bromide powder, 1,000 g of glucose powder and 115.0 g of nitric acid (1N) were dissolved in 12.7 kg of distilled water at 80 ° C. While this liquid was kept at 80 ° C. and stirred at 500 rpm, the additive liquid A was added successively at an addition rate of 250 cc / min, the additive liquid B at 500 cc / min, and the additive liquid C at 500 cc / min. The stirring speed was 200 rpm and heating was performed at 80 ° C. The stirring was continued for 100 minutes after setting the stirring speed to 200 rpm, and then cooled to 25 ° C. The stirring speed was changed to 500 rpm, and additive solution D was added at 500 cc / min. This liquid was used as a silver nanowire dispersion liquid (1).

(Preparation Example 2)
-Preparation of silver nanowire dispersion (2)-
In the preparation of the silver nanowire dispersion liquid (1), a silver nanowire dispersion liquid (2) was prepared in the same manner except that the additive liquid D was not added.

Example 1
<< Silver Nanowire Dispersion (11) >>
The silver nanowire dispersion liquid (1) was put into the addition tank 201 of the apparatus shown in FIG. Next, n-propanol was charged into the second addition tank 202 as a peeling solution for the low molecular dispersant. The first liquid feeding pump 211 and the second liquid feeding pump 212 are operated to feed the silver nanowire dispersion liquid (1) and n-propanol at a flow rate of 300 cc / min, respectively. It mixed with the flow mixing apparatus 221, and the obtained liquid mixture was collect | recovered with the collection tank 203, and it was set as the liquid mixture (11).

<Purification process>
The mixture (11) was subjected to ultrafiltration purification by a crossflow method as follows using an ultrafiltration module having a molecular weight cut off of 150,000. After the liquid mixture (11) was concentrated four times, addition and concentration of a mixed liquid of distilled water and n-propanol (volume ratio = 1: 1) were repeated, and finally the electric conductivity of the liquid concentrate was 0.5 mS / Purification was performed until m. During the purification, the dispersion was purified while backwashing the filter at intervals of 5 minutes in order to prevent solids from being deposited on the filtration filter and reducing the filtration efficiency. The purified liquid was collected and used as a silver nanowire dispersion liquid (11).

  With respect to the silver nanowire of the obtained silver nanowire dispersion liquid (11), the average minor axis length, the average major axis length, the coefficient of variation of the minor axis length of the silver nanowire, and the average aspect ratio were measured as described above. As a result, the average minor axis length was 18.4 nm, the average major axis length was 8.0 μm, and the coefficient of variation was 14.7%. The average aspect ratio was 441.

(Preparation Examples 3 to 6: Pretreatment of substrate)
(Preparation Example 3)
-Pretreatment of PET substrate-
A bonding solution 1 was prepared with the following composition.

[Adhesive solution 1]
-Takelac WS-4000 5.0 parts (solid content concentration 30%, manufactured by Mitsui Chemicals, Inc.)
・ Surfactant 0.3 part (Narrow Acty HN-100, manufactured by Sanyo Chemical Industries)
・ Surfactant 0.3 part (Sandet BL, solid content concentration 43%, Sanyo Chemical Industries, Ltd.)
-94.4 parts of water Corona discharge treatment was performed on one surface of a 125 μm thick PET substrate. The adhesive solution was applied to the surface subjected to the corona discharge treatment and dried at 120 ° C. for 2 minutes to form an adhesive layer 1 having a thickness of 0.11 μm.

  Next, an adhesion solution 2 was prepared with the following composition.

[Adhesive solution 2]
・ Tetraethoxysilane 5.0 parts (KBE-04, manufactured by Shin-Etsu Chemical Co., Ltd.)
・ 3.2 parts of 3-glycidoxypropyltrimethoxysilane (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.)
・ 1.8 parts of 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane (KBM-303, manufactured by Shin-Etsu Chemical Co., Ltd.)
・ Acetic acid aqueous solution (Acetic acid concentration = 0.05%, pH = 5.2) 10.0 parts ・ Curing agent 0.8 parts (Boric acid, manufactured by Wako Pure Chemical Industries, Ltd.)
Colloidal silica 60.0 parts (Snowtex O, average particle size 10 nm to 20 nm, solid content concentration 20%,
(pH = 2.6, manufactured by Nissan Chemical Industries, Ltd.)
・ Surfactant 0.2 part (Narrow Acty HN-100, Sanyo Chemical Industries Co., Ltd.)
・ Surfactant 0.2 parts (Sandet BL, solid content concentration 43%, Sanyo Chemical Industries, Ltd.)
The bonding solution 2 was prepared by the following method. While stirring the aqueous acetic acid solution vigorously, 3-glycidoxypropyltrimethoxysilane was dropped into the aqueous acetic acid solution over 3 minutes. Next, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane was added to the acetic acid aqueous solution over 3 minutes with vigorous stirring. Next, tetramethoxysilane was added to the acetic acid aqueous solution over 5 minutes with vigorous stirring, and then stirring was continued for 2 hours. Next, colloidal silica, a curing agent, and a surfactant were sequentially added to prepare an adhesive solution 2.

  This adhesive solution 2 was applied onto the adhesive layer 1 subjected to the corona discharge treatment by a bar coating method, heated at 170 ° C. for 5 minutes and dried to form an adhesive layer 2 having a thickness of 4.1 μm. Thereafter, a corona discharge treatment was performed on the adhesive layer 2 to obtain a pretreated PET substrate. Hereinafter, the “PET substrate” indicates the PET substrate obtained by the pretreatment.

(Preparation Example 4)
-Pretreatment of glass substrate-
A 0.7 μm-thick alkali-free glass plate immersed in a 1% aqueous solution of sodium hydroxide was subjected to ultrasonic irradiation with an ultrasonic cleaner for 30 minutes, then washed with ion-exchanged water for 60 seconds, and then heat-treated at 200 ° C. for 60 minutes. went. Thereafter, a silane coupling solution (N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane 0.3% aqueous solution (trade name: KBM603, manufactured by Shin-Etsu Chemical Co., Ltd.) was sprayed for 20 seconds with a shower, In the following description, the term “glass substrate” refers to a non-alkali glass substrate obtained by the above pretreatment.

(Preparation Example 5)
-Pretreatment of polycarbonate substrate-
After the surface of the polycarbonate substrate (thickness: 75 μm) was subjected to corona discharge treatment, 0.02% (N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane aqueous solution was applied at a coating amount of 8.8 mg / bar by the bar coating method. The polycarbonate substrate was coated to m2 and dried at 100 ° C. for 1 minute to obtain a surface-treated polycarbonate substrate.Hereinafter, the “polycarbonate substrate” indicates the polycarbonate substrate obtained by the above pretreatment.

(Preparation Example 6)
-Pretreatment of TAC substrate-
After corona discharge treatment of the surface of a TAC (triacetylcellulose) substrate (thickness 100 μm), 0.02% (N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane aqueous solution was applied by a bar coating method. An amount of 8.8 mg / m 2 was applied and dried at 100 ° C. for 1 minute to obtain a surface-treated TAC substrate, hereinafter referred to as “TAC substrate”, obtained by the above pretreatment. A TAC substrate is shown.

(Preparation Example 7)
<< Formation of Conductive Member (1) >>
The silver nanowire dispersion liquid (11) and the following sol-gel coating liquid were mixed at a mass ratio of Ag: tetraethoxysilane (TEOS): = 1: 7.2, and the mixture was placed on the PET substrate obtained in Preparation Example 3. Bar coating was performed so that the amount of silver was 0.017 g / m ^2, and drying was performed at 120 ° C. for 3 minutes to produce a conductive member (1).

<Sol-gel coating solution>
A sol-gel coating solution having the following composition was stirred at 60 ° C. for 1 hour to confirm that it was uniform, and a sol-gel coating solution was obtained.

<Sol-gel coating solution>
・ Tetraethoxysilane 5.0 parts (KBE-04, manufactured by Shin-Etsu Chemical Co., Ltd.)
1% acetic acid aqueous solution 10.5 parts Distilled water 4.0 parts << Patterned conductive member (11) >>
The conductive member (1) was subjected to a patterning process according to the following positive resist formulation to produce a patterned conductive member (11).

<Positive resist formulation>
(Synthesis Example 1)
<Synthesis of Binder (A-1)>
MAA (7.79 g) and BzMA (37.21 g) are used as monomer components constituting the copolymer, AIBN (0.5 g) is used as a radical polymerization initiator, and these are used as a solvent PGMEA (55.00 g). ) To give a PGMEA solution (solid content concentration: 45% by mass) of binder (A-1) represented by the following structural formula. The polymerization temperature was adjusted to 60 to 100 ° C.

  The molecular weight was measured using gel permeation chromatography (GPC). As a result, the weight average molecular weight (Mw) in terms of polystyrene was 30,000, and the molecular weight distribution (Mw / Mn) was 2.21.

-Preparation of photosensitive composition (1)-
4.19 parts by mass of binder (A-1) (solid content: 40.0% by mass, PGMEA solution), TAS-200 represented by the following structural formula as a photosensitive compound (esterification rate: 66%, Toyo Gosei Co., Ltd.) 0.95 parts by mass, EHPE-3150 (manufactured by Daicel Chemical Co., Ltd.) 0.80 parts by mass, and 19.06 parts by mass of PGMEA as a crosslinking agent were added and stirred to prepare a photosensitive composition (1). did.

<< resist patterning process >>
The photosensitive composition (1) was applied onto the conductive member (1) with a bar so as to have a dry film thickness of 5 μm, and dried in an oven at 100 ° C. for 1 minute. This substrate was exposed to 60 mJ / cm ² (illuminance 20 mW / cm ² ) from a mask with a high-pressure mercury lamp i-line (365 nm). The exposed substrate was subjected to shower development for 60 seconds with a 2.38% tetramethylammonium hydroxide aqueous solution. The shower pressure was 0.04 MPa, and the time until the stripe pattern appeared was 30 seconds. After rinsing with a shower of pure water, it was dried at 50 ° C. for 1 minute to prepare a conductive member (1) with a resist pattern.

  The exposure mask had a line / space of 150/150 μm and a thin line length of 1.5 cm.

<< Etching process >>
The conductive member (1) with a resist pattern is applied to an etching solution (1) composed of a mixed aqueous solution of 30%, 1.0% nitric acid, 1.0% Fe (III) -EDTA, 1.0% ammonium thiosulfate. After dipping, etching, rinsing with a shower of pure water, and drying for 1 minute at 50 ° C., a patterned conductive member (1) A with a resist pattern was produced.

<< Resist stripping process >>
The patterned conductive member (1) A with a resist pattern was exposed to 100 mJ / cm ² (illuminance 20 mW / cm ² ) with a high-pressure mercury lamp i-line (365 nm) without masking. The exposed substrate was subjected to shower development for 75 seconds with a 2.38% tetramethylammonium hydroxide aqueous solution. The shower pressure was 0.05 MPa. After rinsing with a shower of pure water, it was dried at 50 ° C. for 1 minute to produce a patterned conductive member (11).

(Example 2)
<< Silver Nanowire Dispersion (12) >>
The silver nanowire dispersion liquid (2) was put into the first addition tank 301 of the apparatus shown in FIG. Next, a polyvinyl pyrrolidone (K30) aqueous solution was put into the second addition tank 302. Further, n-propanol was charged into the third addition tank 303 as a peeling solution for the low molecular dispersant. The first liquid feed pump 311, the second liquid feed pump 312 and the third liquid feed pump 313 are operated, and the silver nanowire dispersion (2) and the polyvinylpyrrolidone (K30) aqueous solution are converted into the silver nanowire dispersion (2 ) At a flow rate of 200 cc / min and an aqueous polyvinylpyrrolidone (K30) solution at a flow rate of 100 cc / min and mixed by the first flow mixing device 321 having a T-shaped flow path, and then n-propanol is added at 300 cc / min. The liquid was fed at a flow rate of min and mixed by the second flow mixing device 322 having a T-shaped channel, and the obtained liquid mixture was recovered by the recovery tank 304 to obtain a liquid mixture (12).

<Purification process>
The mixed solution (12) was subjected to ultrafiltration purification by a cross flow method as follows using an ultrafiltration module having a molecular weight cut off of 150,000. After the liquid mixture (12) was concentrated four times, addition and concentration of a mixture of distilled water and n-propanol (volume ratio = 1: 1) were repeated, and finally the electric conductivity of the liquid concentrate was 0.5 mS / Purification was performed until m. During the purification, the dispersion was purified while backwashing the filter at intervals of 5 minutes in order to prevent solids from being deposited on the filtration filter and reducing the filtration efficiency. The purified liquid was collected and used as a silver nanowire dispersion liquid (12).

  With respect to the silver nanowire of the obtained silver nanowire dispersion liquid (12), the average minor axis length, the average major axis length, the coefficient of variation of the minor axis length of the silver nanowire, and the average aspect ratio were measured as described above. As a result, the average minor axis length was 18.5 nm, the average major axis length was 8.1 μm, and the coefficient of variation was 14.6%. The average aspect ratio was 439.

<< Patterned conductive member (12) >>
In the production of the patterned conductive member (11), the patterned conductive member (12) was produced in the same manner except that the silver nanowire dispersion liquid (11) was changed to the silver nanowire dispersion liquid (12).

(Example 3)
<< Silver nanowire dispersion (13) >>
The silver nanowire dispersion liquid (2) was put into the addition tank 201 of the apparatus shown in FIG. Next, polyvinyl pyrrolidone (K30) was dissolved in n-propanol and charged into the second addition tank 202. The first liquid feeding pump 211 and the second liquid feeding pump 212 are operated, and the silver nanowire coarse dispersion liquid (1) and n-propanol are fed at a flow rate of 300 cc / min, respectively. Were mixed by the flow mixing device 221, and the obtained mixed liquid was recovered by the recovery tank 203 to obtain a mixed liquid (13).

<Purification process>
The mixture (13) was subjected to ultrafiltration purification by a crossflow method as follows using an ultrafiltration module having a molecular weight cut off of 150,000. After the mixture (13) was concentrated four times, addition and concentration of a mixture of distilled water and n-propanol (volume ratio = 1: 1) were repeated, and finally the conductivity of the concentrate was 0.5 mS / Purification was performed until m. During the purification, the dispersion was purified while backwashing the filter at intervals of 5 minutes in order to prevent solids from being deposited on the filtration filter and reducing the filtration efficiency. The purified liquid was collected and used as a silver nanowire dispersion liquid (13).

  With respect to the silver nanowire of the obtained silver nanowire dispersion liquid (13), the average minor axis length, the average major axis length, the coefficient of variation of the minor axis length of the silver nanowire, and the average aspect ratio were measured as described above. As a result, the average minor axis length was 18.3 nm, the average major axis length was 8.1 μm, and the variation coefficient was 14.5%. The average aspect ratio was 438.

<< Patterned conductive member (13) >>
In the production of the patterned conductive member (11), a patterned conductive member (13) was produced in the same manner except that the silver nanowire dispersion liquid (11) was changed to the silver nanowire dispersion liquid (13).

Example 4
<< Silver nanowire dispersion (14) >>
While vigorously stirring n-propanol, the silver nanowire dispersion liquid (1) was added (so-called batch mixing), and stirring was continued for 3 minutes to obtain a mixed liquid (14).

<Purification process>
The mixed solution (14) was subjected to ultrafiltration purification by a cross flow method as follows using an ultrafiltration module having a molecular weight cut off of 150,000. After the mixture (14) was concentrated four times, addition and concentration of a mixture of distilled water and n-propanol (volume ratio = 1: 1) were repeated, and finally the conductivity of the concentrate was 0.5 mS / Purification was performed until m. During the purification, the dispersion was purified while backwashing the filter at intervals of 5 minutes in order to prevent solids from being deposited on the filtration filter and reducing the filtration efficiency. The refined liquid was collect | recovered and it was set as the silver nanowire dispersion liquid (14).

  As for the silver nanowire of the obtained silver nanowire dispersion liquid (14), the average minor axis length, the average major axis length, the coefficient of variation of the minor axis length of the silver nanowire, and the average aspect ratio were measured as described above. As a result, the average minor axis length was 18.2 nm, the average major axis length was 8.0 μm, and the variation coefficient was 14.4%. The average aspect ratio was 440.

<< Patterned conductive member (14) >>
A patterned conductive member (14) was produced in the same manner as in the production of the patterned conductive member (11) except that the silver nanowire dispersion liquid (11) was changed to the silver nanowire dispersion liquid (14).

(Example 5)
<< Silver nanowire dispersion (15) >>
In the preparation of the silver nanowire dispersion liquid (11), instead of the cross flow purification, the liquid mixture (1) was centrifuged at 2000 rpm for 20 minutes using a centrifuge. Thereafter, the supernatant was removed, and a mixed solution of distilled water and n-propanol (volume ratio = 1: 1) was added. Centrifugation was repeated until the electrical conductivity of the supernatant liquid reached 0.5 mS / m, and the obtained liquid was collected to obtain a silver nanowire dispersion liquid (15).

  For the silver nanowires of the obtained silver nanowire dispersion liquid (15), the average minor axis length, the average major axis length, the coefficient of variation of the minor axis length of the silver nanowires, and the average aspect ratio were measured as described above. As a result, the average minor axis length was 18.4 nm, the average major axis length was 8.2 μm, and the coefficient of variation was 14.5%. The average aspect ratio was 438.

<< Patterned conductive member (15) >>
In the production of the patterned conductive member (11), a patterned conductive member (15) was produced in the same manner except that the silver nanowire dispersion liquid (11) was changed to the silver nanowire dispersion liquid (15).

(Comparative Example 1)
<< Silver nanowire dispersion (C1) >>
The silver nanowire dispersion liquid (1) was mixed with n-propanol, which is a release liquid of a low molecular dispersant, using an ultrafiltration module with a molecular weight cut off of 150,000, as follows. Ultrafiltration purification was performed. After the mixture (14) was concentrated four times, addition and concentration of a mixture of distilled water and n-propanol (volume ratio = 1: 1) were repeated, and finally the conductivity of the concentrate was 0.5 mS / Purification was performed until m. During the purification, the dispersion was purified while backwashing the filter at intervals of 5 minutes in order to prevent solids from being deposited on the filtration filter and reducing the filtration efficiency. The refined liquid was collect | recovered and it was set as the silver nanowire dispersion liquid (C1).

  With respect to the silver nanowire of the obtained silver nanowire dispersion liquid (C1), the average minor axis length, the average major axis length, the coefficient of variation of the minor axis length of the silver nanowire, and the average aspect ratio were measured as described above. As a result, the average minor axis length was 18.4 nm, the average major axis length was 8.0 μm, and the variation coefficient was 14.4%. The average aspect ratio was 437.

<< Patterned conductive member (C1) >>
A patterned conductive member (C1) was produced in the same manner as in the production of the patterned conductive member (11) except that the silver nanowire dispersion liquid (11) was changed to the silver nanowire dispersion liquid (C1).

(Comparative Example 2)
<< Silver nanowire dispersion (C2) >>
In the production of the silver nanowire dispersion liquid (11), the same procedure was followed except that the liquid charged into the addition tank 101 was changed from the silver nanowire dispersion liquid (1) to the silver nanowire dispersion liquid (2) not containing polyvinylpyrrolidone. A nanowire dispersion (C2) was prepared.

  With respect to the silver nanowire of the obtained silver nanowire dispersion liquid (C1), the average minor axis length, the average major axis length, the coefficient of variation of the minor axis length of the silver nanowire, and the average aspect ratio were measured as described above. As a result, the average minor axis length was 18.6 nm, the average major axis length was 8.1 μm, and the variation coefficient was 14.4%. The average aspect ratio was 438.

<< Patterned conductive member (C2) >>
A patterned conductive member (C2) was produced in the same manner as in the production of the patterned conductive member (11) except that the silver nanowire dispersion liquid (11) was changed to the silver nanowire dispersion liquid (C2).

(Comparative Example 3)
<< Silver nanowire dispersion (C3) >>
In the production of the silver nanowire dispersion liquid (11), the purification step was not carried out, and the silver nanowire dispersion liquid (C3) was produced in the state of the mixed liquid (1).

  With respect to the silver nanowire of the obtained silver nanowire dispersion liquid (C1), the average minor axis length, the average major axis length, the coefficient of variation of the minor axis length of the silver nanowire, and the average aspect ratio were measured as described above. As a result, the average minor axis length was 18.3 nm, the average major axis length was 8.1 μm, and the coefficient of variation was 14.6%. The average aspect ratio was 440.

<< Patterned conductive member (C3) >>
A patterned conductive member (C3) was produced in the same manner as in the production of the patterned conductive member (11) except that the silver nanowire dispersion liquid (11) was changed to the silver nanowire dispersion liquid (C3).

<< Evaluation >>
About the obtained patterned electroconductive member, resistance value, transparency, and various durability were evaluated by the below-mentioned method. The evaluation results are shown in Tables 1 and 2.

<Surface resistance value>
The surface resistance of the conductive region of the conductive layer was measured using Loresta-GP MCP-T600 manufactured by Mitsubishi Chemical Corporation.

<Optical characteristics (total light transmittance)>
The total light transmittance (%) of the patterned conductive member was measured using a haze guard plus manufactured by Gardner.

<Optical properties (haze)>
The haze (%) of the patterned conductive member was measured using a haze guard plus manufactured by Gardner.

<Damp heat durability>
The patterned conductive member was exposed to an environment of 85 ° C./85% RH (relative humidity) for 120 hours, the resistance value before exposure was R0, and the resistance value after exposure was R, and the following ranking was performed. . In addition, it has shown that performance is so good that the number of a rank is large, and it is a level which is satisfactory practically in rank 3 or more.

〔Evaluation criteria〕
5: R / R0 is 0.9 or more and less than 1.1 4: R / R0 is 1.1 or more and less than 1.2, or 0.8 or more and less than 0.9 3: R / R0 is 1.2 Or more, less than 1.3, or 0.7 or more, less than 0.8 2: R / R0 is 1.3 or more, less than 1.5, or 0.6 or more, less than 0.7 1: R / R0 is 1 .5 or more, or less than 0.6 <Migration resistance>
In the environment of 40 ° C./70% RH (relative humidity), the patterned conductive member is continuously applied with a voltage of DC 3V between adjacent electrodes for 24 hours, the resistance value before application is R0, and the resistance after application The following ranking was performed with the value R. In addition, it has shown that performance is so good that the number of a rank is large, and it is a level which is satisfactory practically in rank 3 or more.

〔Evaluation criteria〕
5: R / R0 is 0.9 or more and less than 1.1 4: R / R0 is 1.1 or more and less than 1.2, or 0.8 or more and less than 0.9 3: R / R0 is 1.2 Or more, less than 1.3, or 0.7 or more, less than 0.8 2: R / R0 is 1.3 or more, less than 1.5, or 0.6 or more, less than 0.7 1: R / R0 is 1 .5 or more, or less than 0.6 <Flexibility>
Using a cylindrical mandrel bending tester manufactured by Cortec Co., Ltd., the conductive member was subjected to a bending test 20 times on a cylindrical mandrel having a diameter of 10 mm. Resistance value R / surface resistance value R0 before bending test) was measured, and the following ranking was performed. The presence or absence of cracks was measured visually and using an optical microscope, and the surface resistance value was measured using Loresta-GP MCP-T600 manufactured by Mitsubishi Chemical Corporation. Flexibility is better as there is no crack and the change in the surface resistance value is smaller (closer to 1). The larger the rank number, the better the performance. At rank 3 or higher, there is no practical problem.

〔Evaluation criteria〕
5: R / R0 is 0.9 or more and less than 1.1 4: R / R0 is 1.1 or more and less than 1.2, or 0.8 or more and less than 0.9 3: R / R0 is 1.2 Or more, less than 1.3, or 0.7 or more, less than 0.8 2: R / R0 is 1.3 or more, less than 1.5, or 0.6 or more, less than 0.7 1: R / R0 is 1 .5 or more, or less than 0.6 <Abrasion resistance>
The surface of the conductive layer of the conductive member is rubbed 50 times with a load of 500 g with a size of 20 mm × 20 mm using gauze (Zabina Minimax, manufactured by KB Seiren). Surface resistance value R / surface resistance value R0 before wear) was measured, and the following ranking was performed. For the abrasion test, a continuous load scratch tester Type 18s manufactured by Shinto Kagaku Co., Ltd. and the surface resistance value were measured using Loresta-GP MCP-T600 manufactured by Mitsubishi Chemical Corporation. As the surface is less scratched and the change in the surface resistance value is smaller (closer to 1), the wear resistance is superior. At rank 3 or higher, there is no practical problem.

〔Evaluation criteria〕
5: R / R0 is 0.9 or more and less than 1.1 4: R / R0 is 1.1 or more and less than 1.2, or 0.8 or more and less than 0.9 3: R / R0 is 1.2 Or more, less than 1.3, or 0.7 or more, less than 0.8 2: R / R0 is 1.3 or more, less than 1.5, or 0.6 or more, less than 0.7 1: R / R0 is 1 .5 or more, or less than 0.6

  From the results of Tables 1 and 2, Example 1-5 had a lower resistance value and higher transparency than Comparative Example 1-3. Moreover, according to Example 1-5, flow mixing is preferable as a mixing method, and crossflow is preferable as purification.

(Examples 6 to 8)
In the production of the patterned conductive member (11), except that the base material was changed to the glass substrate produced in Preparation Example 4, the polycarbonate substrate produced in Preparation Example 5, and the TAC substrate produced in Preparation Example 6, Patterned conductive members (21) to (23) were produced. Tables 3 and 4 show details of the manufactured patterned conductive members.

<< Evaluation >>
About the obtained patterned electroconductive member (21)-(23), resistance value, transparency, and various durability were evaluated by the above-mentioned method. The evaluation results are shown in Table 4. In addition, about a patterned electroconductive member (21), since a base material is a glass substrate without a flexibility, the flexibility test is not implemented. From the results of Tables 3 and 4, the patterned conductive member had a low resistance value and high transparency regardless of the type of substrate.

Example 9
The patterned conductive member (11) was produced by using a slot die coater having an extrusion type coating head equipped with a backup roller, as exemplified in JP-A-2006-95454, instead of the bar coating method. Similarly, a patterned conductive member (31) was produced.

<< Evaluation >>
About the obtained patterned electroconductive member (31), resistance value, transparency, and various durability were evaluated by the above-mentioned method. The evaluation results are shown in Table 5.

(Example 10)
-Fabrication of touch panel-
Using the transparent conductive film of the patterned conductive member (21), "Latest Touch Panel Technology" (issued July 6, 2009, Techno Times Co., Ltd.), supervised by Yuji Mitani, "Touch Panel Technology and Development", CMC A touch panel was produced by the method described in Publication (issued in December 2004), “FPD International 2009 Forum T-11 Lecture Textbook”, “Cypress Semiconductor Corporation Application Note AN2292”, and the like.

  When the manufactured touch panel is used, it is excellent in pattern shape visibility of the patterned conductive member, and input of characters etc. or screen operation with at least one of bare hands, hands wearing gloves, pointing tool by improving conductivity It was found that a touch panel with excellent responsiveness can be manufactured.

<Production of solar cell>
(Example 11)
-Fabrication of amorphous solar cells (super straight type)-
On the glass substrate, the electroconductive layer was formed like the patterned electroconductive member (21), and the transparent conductive film was formed. However, the patterning process was not performed, and the entire surface was made a transparent conductive film. A p-type film with a film thickness of about 16 nm, an i-type film with a film thickness of about 350 nm, and an n-type amorphous silicon film with a film thickness of about 30 nm are formed thereon, and a gallium-doped zinc oxide layer of 20 nm and a silver layer of 200 nm are formed as back reflecting electrodes. To form a photoelectric conversion element (integrated solar cell).

(Example 12)
-Fabrication of CIGS solar cells (substrate type)-
On a soda lime glass substrate, a molybdenum electrode having a film thickness of about 500 nm by a direct current magnetron sputtering method, and Cu (In _0.6 Ga _0.4 ) Se which is a chalcopyrite semiconductor material having a film thickness of about 2.6 μm by a vacuum deposition method. _Two thin films, a cadmium sulfide thin film having a film thickness of about 48 nm, were formed by a solution deposition method.

  The same conductive layer as the conductive layer of the patterned conductive member (21) was formed thereon, a transparent conductive film was formed on the glass substrate, and a photoelectric conversion element (CIGS solar cell) was produced. However, a patterning process after the formation of the conductive layer was not performed, and the entire surface was made a transparent conductive film.

<Evaluation of solar cell characteristics (conversion efficiency)>
About the solar cell produced in Example 11 and 12, efficiency was measured by irradiating the artificial sunlight of AM1.5 and 100 mW / cm < ² >. As a result, each element showed a conversion efficiency of 9.0%. From this result, it was found that high conversion efficiency can be obtained in any integrated solar cell system by using the conductive member of the present embodiment for forming.

  10, 60, 70, 100 ... flow mixing device, 201, 301 ... first addition tank, 202, 302 ... second addition tank, 211, 311 ... first feed pump, 212, 312 ... second Liquid feed pump, 221... Flow mixing device, 303... Third addition tank, 313... Third liquid feed pump, 321... First flow mixing device, 322.

Claims (5)

An aqueous dispersion containing silver nanowires surface-modified with a low molecular dispersant, a polymer dispersant, and a release solution for peeling the low molecular dispersant from the silver nanowires are prepared, and the polymer dispersant is A mixing step of mixing the aqueous dispersion and the release solution in a state of being included in at least one of the aqueous dispersion and the release solution;
A purification step of separating and removing the low molecular weight dispersant from the mixed solution prepared in the mixing step, and a method for producing a silver nanowire dispersion,
The low molecular dispersant has a function of controlling the form of the silver nanowire and preventing aggregation when reducing the metal ions in an aqueous solvent to synthesize the silver nanowire, and the polymer dispersant is A method for producing a silver nanowire dispersion liquid, wherein the silver nanowires are adsorbed on the surface of the silver nanowires at intervals and have a function of preventing aggregation of the silver nanowires.   The said mixing process is a manufacturing method of the silver nanowire dispersion liquid of Claim 1 including flow-mixing the said peeling solution and the said water dispersion liquid.   The polymer dispersant is any one of flow mixing using a solution containing the polymer dispersant and batch mixing using the polymer dispersant or a solution containing the polymer dispersant. The manufacturing method of the silver nanowire dispersion liquid of Claim 1 or 2 added to at least any one of an aqueous dispersion liquid and the said peeling solution.   The method for producing a silver nanowire dispersion liquid according to claim 2, wherein the flow mixing includes being performed using a T-shaped channel.   The manufacturing method of the silver nanowire dispersion liquid of any one of Claim 1 to 4 including the said refinement | purification process being implemented by filtration of a crossflow system.

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