KR20150079330A - a metal mesh including a metal nanorod, and a method of fabricating a metal mesh using metal nanorod ink - Google Patents

Abstract

The present invention relates to a method of fabricating a metal mesh for a touch panel using metal nanorod ink and a metal mesh including a metal nanorod. The metal mesh is fabricated by a printing process using metal nanorod ink. According to the present invention, in comparison with a metal mesh using existing metal nanoparticle ink, the present invention can realize a metal mesh with superior transmittance and electric conductivity even though it is used at a lower temperature or ink of a lower concentration than the existing ink is used. It can be used for coating, contact type printing or non-contact type printing.

Description

METHOD FOR MANUFACTURING METAL MESH USING METAL NANO LOD AND METAL NANO-LORD INK United States Patent Application 20100264761 Kind Code: A1 A metal mesh including a metal nano-rod and a method for fabricating a metal nano-

The present invention provides a metal mesh having metal nano-rods and a metal ink having a lower concentration than that of a general metal paste. The pattern is realized by a metal mesh having excellent electrical and optical characteristics And a method for producing the same.

Recent developments in flat panel displays and solar cells have dramatically increased the use of transparent electrode materials. However, the transparent electrode material based on the conventional ITO (indium tin oxide) has been actively studied for the development of a new transparent electrode material due to the depletion of indium and the low conductivity of the material. There is a problem that the unit price rises due to the expensive vacuum equipment used in the manufacture of the ITO thin film, the ITO electrode tends to be easily broken by the external impact, and the thin film is bent or the mechanical stability is weak when folded. In recent years, flexible electronic devices manufactured based on printing technology have emerged as core devices of the next generation, and studies on transparent electrode materials and processes that can be applied to these devices are also receiving attention.

Transparent electrodes are functional thin film electrodes that transmit light in the visible light region and have electrical conductivity and are widely used as electrode substrates for flat panel displays, touch panels, and solar cells. In order to obtain a transparent electrode having excellent surface resistance, it is required to satisfy two conditions that the sheet resistance is not more than 200? / Cm ² and the transmittance in the visible light region of 380 to 780 nm is not less than 85%. The newly emerging electrode is a transparent electrode in the form of a metal grid that increases the transmittance by giving a pattern to the metal electrode. When the metal electrode is finely patterned to form a nano-mesh, the transmittance increases and the high conductivity of the metal itself is maintained. Therefore, high transmittance and low sheet resistance, which are indispensable elements of the transparent electrode, can be realized at the same time.

In the past, it was implemented through a conventional process mainly through deposition and etching processes, but in recent years efforts to realize various printing methods have been made. Next-generation electronic products such as flexible displays, RFID, and solar cells can be manufactured in a printing process that is less expensive than electronic products based on conventional silicon semiconductors, thereby realizing large-area, lightweight, and low-cost products.

Inkjet printing is expressed as a point in which pattern formation is regularly arranged in a non-impact printing method in which very small ink droplets collide with a substrate to form an image. Inkjet is disadvantageous in that the ink nozzle is likely to be clogged, the density of the pattern is low, and the throughput is low, thereby improving the productivity.

In the case of using nanowire ink, it is difficult to form a metal mesh by using a printing process because a nozzle can easily clog due to the nature of a nanowire having a micrometer length itself. In addition, when silver nanoparticle inks are used, contact between nanoparticles must occur. Therefore, in order to increase conductivity, silver (Ag) nanoparticles having a high concentration must be sufficiently fired at a high temperature.

Korean Patent Publication No. 10-2011-0108315

INDUSTRIAL APPLICABILITY The present invention can realize a metal mesh having excellent transparency and electrical conductivity even when a lower concentration ink is used and also at a lower temperature as compared with the case of producing a metal mesh using the metal nanoparticle ink, It is another object of the present invention to provide a method of manufacturing a metal mesh type transparent electrode using a metal nano-rod ink which can be applied to contact printing or non-contact printing.

One aspect of the present invention may be a metal mesh including a metal nano-rod.

The metal nano-rod may have an aspect ratio of 5 to 100, and the metal nano-rod may be at least one selected from the group consisting of Au, Ag, Cu, Ni, Fe, , Zinc (Zn), chromium (Cr), manganese (Mn), or combinations thereof.

Another aspect of the present invention is a method of manufacturing a metal mesh, which comprises printing a metal nano-rod ink on a substrate and then firing the metal nano-rod ink.

The average aspect ratio of the metal nano-rods contained in the metal nano-rod ink may be 5 to 100.

The concentration of the metal nanorods in the ink may be 1 to 60 wt%.

The metal nano-rods are made of a metal such as Au, Ag, Cu, Ni, Fe, Co, Zn, Cr, A rod, or a combination thereof.

The printing can be carried out by coating, contact printing or non-contact printing. Slit-die coating, bar coating and the like are available for the coating. The contact printing includes gravure printing, offset printing offset printing, reverse offset printing, screen printing or nano-imprint lithography. Non-contact printing includes spray printing, microarray printing, , Direct laser imaging, or inkjet printing.

The firing can be carried out at 100 to 250 ° C.

According to the present invention, as compared with the case of producing a metal mesh using the conventional metal nano-particle ink, it is possible to realize a metal mesh having lower transparency and electrical conductivity even when firing at a lower temperature and at a lower temperature , Coating, contact printing, or non-contact printing.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an enlarged photograph of a metal mesh produced according to the present invention and a microstructure of a metal part. FIG.
2 is a scanning electron micrograph showing silver (Ag) nanowires and silver nano rods used in the present invention (A: silver (Ag) nanowire used for manufacturing silver (Ag) Silver (Ag) nanorod).
3 is a scanning electron micrograph (A: Comparative Example 1, B: Example 1) showing the microstructure of the metal portion of the metal mesh according to Comparative Examples and Examples.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Furthermore, embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art. Accordingly, the shapes and sizes of the elements in the drawings may be exaggerated for clarity of description, and the elements denoted by the same reference numerals in the drawings are the same elements.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an enlarged photograph of a metal mesh produced according to the present invention and a microstructure of a metal part. FIG.

Referring to FIG. 1, one aspect of the present invention may be a metal mesh including metal nano-rods. The metal nano-rods may have an aspect ratio of 5 to 100 and the metal nano-rods may be selected from the group consisting of gold (Au), silver (Ag), copper (Cu), nickel (Ni), iron (Fe), cobalt ), Zinc (Zn), chromium (Cr), manganese (Mn), or combinations thereof.

Another aspect of the present invention is a method of manufacturing a metal mesh, which comprises printing a metal nano-rod ink on a substrate and then firing the metal nano-rod ink. That is, this aspect is characterized in that a metal nano-rod ink is used in manufacturing a metal mesh for a touch panel using a printing process.

According to this aspect, by using the metal nano-wire ink instead of using the metal nano-wire ink or the metal nano-particle ink, the problems such as clogging of the nozzle are solved when the metal nano wire ink is used, It is possible to solve the problem of having high filling rate and high temperature firing in order to obtain excellent electrical properties.

As the substrate, a plastic substrate such as polyethylene terephthalate, polyimide, or a glass substrate can be used.

The ink may include metal nano-rods, dispersants, and other additives in the solvent.

The metal nano-rods can be synthesized and prepared, but it is preferable to prepare the metal nanowires by grinding. The synthesized metal nanorods may have different growth rates of the nanorods during synthesis, so that it is difficult to obtain nanorods having a uniform length, while the metal nanorods obtained by grinding the nanorods are relatively uniform in length.

As the metal nano-rod, an average aspect ratio of 5 to 100 can be used. For example, if the diameter of the nanorod is 45 nm and the length is 900 nm, the aspect ratio is 20. When the aspect ratio of the metal nano-rod is out of the above range, the difference is small as compared with the case of using the metal nanowire or the metal nanoparticle.

The concentration of the metal nano-rods in the ink may be 1 to 60 wt%. When the concentration of the metal nano-rod is less than 1 wt%, the contact between the nano-rods is not properly performed, and the electrical conductivity may decrease after firing. When the concentration is more than 60 wt%, it is difficult to ensure printability and to secure surface properties after printing In addition, a large amount of silver (Ag) nanorods may be required, which may increase the production cost.

As the metal nano-rods, a metal such as Au, Ag, Cu, Ni, Fe, Co, Zn, Cr, Nano rod, or a combination thereof. However, there is a problem that copper nano-rods and the like are liable to be oxidized. In consideration of electric conductivity, it is preferable to use silver (Ag) nano-rods.

Examples of the solvent include ethers (tetrahydrofuran, ethyl ether, propyl ether, methyl ethyl ketone), benzene series (xylene, toluene, ethylbenzene, benzene), alcohols (methanol, ethanol, butanol, propanol, ethylene glycol, propylene glycol (Dimethylformamide, dipropamine, ethylamine, ammonia, ethanolamine, diethanolamine, triethanolamine, triethylamine), and the like, Alkyl-based (hexane, pentane, butane), water or a combination thereof.

Dispersants and other additives may be selected from known materials used in the production of metal inks. Specifically, polyvinylpyrrolidone (PVP), polyacrylic acid (PAA), sodium dodecyl sulfonate (SDS), polyethylene (20) sorbitan monolaurate (Polyoxyethylene (20) sorbitan monolaurate (Tween 20 ^ㄾ) as a dispersing agent ), alkyl diphenyl oxide di-sulfonate (Alkyldiphenyloxide Disulfonate (DOWUFAX ^ㄾ)), based on the weight of the cellulose-based and the total ink polymer resins of the resin such as epoxy series as an interface binder to the total from 0.01% to 5% by weight, surfactants such as 0.1% to 10%. (NH ₃ ), dimethylamine (NH (CH ₃ ) ₂ ), trimethylamine (N (CH ₃ ) ₃ ), ethylamine (NH ₂ Et), diethylamine (NH (Et) ₂ ) or triethylamine (NEt ₃ ) in an amount of 10 to 50% based on the total weight.

In order to improve the dispersibility, ultrasonic waves, eddy current stirring, mechanical stirring, or ball mill or roll mill may be used. For example, in the case of ultrasonic agitation, it is preferably about 5 minutes to about 2 hours at 5 to 50 Hz, and about 10 minutes to about 4 hours at 50 to 1000 rpm for swirling agitation. In the case of a ball mill, Solution at a weight ratio of 1: 1 and stirring for 4 to 24 hours is preferable.

 The printing method can be divided into contact printing and non-contact printing, depending on the method of coating and whether the printing is performed through direct contact between the ink, the plate, and the print. The coating method includes a slit-die coating, bar coating, and spin coating. Examples of contact printing include gravure, offset, screen printing, and nano-imprint lithography. Typical examples of noncontact printing include microarray printing, direct laser imaging, and inkjet printing . In the case of using the metal nanowire ink, there is a problem that the nozzle is clogged due to the characteristics of the wire, so that it is not used for the non-contact type printing. However, this problem does not occur because the nanorod is used instead of the nanowire. Therefore, this aspect has the advantage that not only contact printing but also non-contact printing can be used.

The printed metal mesh can be fired to remove volatile substances such as solvents, and the organic compound additive and the like can be decomposed and removed. The firing temperature is sufficient at a temperature sufficient to remove the solvent and other additives to be added to the ink, and is preferably 100 to 250 ° C. If the firing temperature is lower than 100 ° C, the organic compound additive is not completely removed, which may increase the resistance of the metal mesh. If the sintering temperature is higher than 250 ° C, there may be a problem that it is difficult to apply to the disconnection of the nanorod and the polymer film.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

Examples 1 to 3

1.03 g of AgNO ₃ was dissolved in 3.72 g of propylene glycol to prepare a silver (Ag) precursor solution. 131.67 g of propylene glycol was charged into a reaction vessel of 250 ml, to which 0.83 g of polyvinylpyrrolidone and 0.017 g of tetrabutylammonium chloride were added, and the mixture was stirred for 1 hour while heating to 100 占 폚. The silver (Ag) precursor solution was added dropwise at a rate of 0.25 ml / min using a syringe pump. After completion of the dropwise addition, the reaction was maintained for 4 hours, followed by quenching with water, and centrifugation and washing to prepare silver (Ag) nanowires.

A total of 10 g of a dispersion was prepared by adding 0.003 g of HPMC (Hydroxypropyl methylcellulose), 0.002 g of a dispersant (TX-100 ^® (p-tertiary-octylphenoxypolyethylalcohol)) and 1 g of silver (Ag) Was sonicated to produce a silver (Ag) nano-rod ink having a concentration of 10 wt%.

Silver (Ag) using nanorods ink glass substrate (Samsung Corning Precision Materials (Note) eagle glass ^®) on the ink jet printer (uni-jet (社), omni-jet 100) for 1 minute in printing a metal mesh and 60 ℃ in After drying, the metal mesh was produced by baking at 160 ° C for 10 minutes (Example 1), 250 ° C for 5 minutes (Example 2) and 250 ° C for 10 minutes (Example 3).

Comparative Examples 1 to 3

1.03 g of AgNO ₃ was dissolved in 3.72 g of propylene glycol to prepare a silver (Ag) precursor solution. 131.67 g of propylene glycol was placed in a 250 ml reaction vessel, and 0.83 g of polyvinylpyrrolidone was added thereto, followed by stirring while heating to 100 占 폚. The silver (Ag) precursor solution was added dropwise at a rate of 5 ml / min using a syringe pump. After the dropwise addition, the mixture was maintained for 20 hours, quenching with water, and centrifugation and washing to obtain silver (Ag) nanoparticles.

A dispersion of 10 g in total was prepared by adding 0.003 g of HPMC (Hydroxypropyl methylcellulose), 0.002 g of a dispersant (TX-100 ^® (p-tertiary-octylphenoxypolyethylalcohol)) and 2.5 g of silver (Ag) (Ag) nanoparticles were uniformly dispersed to prepare a 25 wt% silver (Ag) nanoparticle ink.

A metal mesh was printed on a glass substrate with an inkjet printer (UniJet, OmniJet 100) using silver (Ag) nano-particle ink, dried at 60 ° C for 1 minute, and dried at 160 ° C for 10 minutes (Comparative Example 1) , And calcined at 250 캜 for 5 minutes (Comparative Example 2) and at 250 캜 for 10 minutes (Comparative Example 3) to produce a metal mesh.

Example 4

A metal mesh was prepared in the same manner as in Example 1, except that a silver (Ag) nano-rod ink having a silver (Ag) nano-rod concentration of 10 wt% was used and that the ink was fired at 150 캜 for 10 minutes.

Comparative Example 4

A metal mesh was prepared in the same manner as in Comparative Example 1, except that silver (Ag) nanoparticle inks having a concentration of silver (Ag) nanoparticles of 30 wt% were used and those were fired at 250 DEG C for 10 minutes.

evaluation

The aspect ratio of the nanorod

The silver nanowires and the silver nanorods after they were pulverized were observed with a scanning electron microscope (SEM) (Jeol, JSM-7400F), and the results are shown in FIGS. 2 (A) and 2 Respectively. The silver (Ag) nanorods had an average diameter of about 50 nm, an average length of about 1000 nm, and an aspect ratio of 20.

Firing temperature and sheet resistance

Specimens for measuring the sheet resistance of the metal part of the metal mesh were prepared by the following method. That is, the silver (Ag) nano-rod ink of Example was spin-coated on each of three 3 cm x 3 cm glass substrates, and then dried at 60 ° C for 1 minute and then heated at 160 ° C for 10 minutes (corresponding to Example 1) Minute (corresponding to Example 2) and 250 占 폚 for 10 minutes (corresponding to Example 3). In the case of the comparative example, the test piece was prepared in the same manner. The sheet resistance was measured 5 times by 4 point probe method (Mitsubishi, MCP-T370), and the average sheet resistance is shown in Table 1.

Firing temperature (캜) Firing time (minutes) Sheet resistance (Ω / □) Example 1 160 10 95 Example 2 250 5 92 Example 3 250 10 81 Comparative Example 1 160 10 Not measurable Comparative Example 2 250 5 580 Comparative Example 3 250 10 110

In Table 1, 'non-measurable' means that organic materials remained after firing and the current could not flow and thus the measurement could not be performed. From the above results, it can be seen that, in the case of producing the metal mesh using the silver (Ag) nano-rod ink of the present invention, compared with the case of producing the metal mesh using the silver (Ag) It is possible to fabricate a lower metal mesh.

Ink concentration and transmittance

The concentration of each ink for realizing the same sheet resistance was compared through Example 4 and Comparative Example 4, and in this case, the light transmittance of the metal portion of the metal mesh was examined.

FIG. 3 shows scanning electron microscope photographs of the metal portions of the metal mesh prepared according to Comparative Examples 4 and 4 (A: Comparative Example 4, B: Example 4). Referring to FIG. 3, in the case of Comparative Example 4, the nanoparticles are densely packed so that there is almost no gap between the particles. In the case of Example 4, however, it can be seen that the nanorods are gently filled and voids are formed between the nanorods.

The transmittance was measured at a visible light wavelength range of 400 nm to 700 nm using a visible light transmittance meter (JASCO, V-660), and the results are shown in Table 2.

Ink concentration (wt%) Plasticity Transmittance (%) Sheet resistance (Ω / □) Example 4 30 150 ° C, 10 minutes 2.5 28 Comparative Example 4 30 250 ° C, 10 minutes 0 98

Referring to Table 2, Example 4 shows the same performance in terms of sheet resistance despite the lower concentration than in the case of the silver (Ag) nano-particle ink of Comparative Example 4 in the case of using silver (Ag) It can be confirmed that the performance is better. As can be seen from FIG. 3, the fact that the transmittance of the fourth embodiment is higher than that of the fourth comparative example can be attributed to the existence of a lot of voids in the case of the fourth embodiment.

The terms used in the present invention are intended to illustrate specific embodiments and are not intended to limit the invention. The singular presentation should be understood to include plural meanings, unless the context clearly indicates otherwise. The word "comprises" or "having" means that there is a feature, a number, a step, an operation, an element, or a combination thereof described in the specification. The present invention is not limited by the above-described embodiments and the accompanying drawings, but is intended to be limited only by the appended claims. It will be apparent to those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. something to do.

Claims (10)

Metal mesh containing metal nano-rod. The method according to claim 1,
Wherein the metal nano-rod has an aspect ratio of 5 to 100. The method according to claim 1,
The metal nano-rod may be formed of a metal such as gold (Au), silver (Ag), copper (Cu), nickel (Ni), iron (Fe), cobalt (Co), zinc (Zn), chromium (Cr) Nanorods, or combinations thereof. A method for manufacturing a metal mesh, comprising: printing a metal nano-rod ink on a substrate and then firing the metal nano-rod ink. 5. The method of claim 4,
Wherein the aspect ratio of the metal nano-rods included in the metal nano-rod ink is 5 to 100. 5. The method of claim 1, The method according to claim 4 or 5,
Wherein the metal nanorods are produced by grinding metal nanowires. 5. The method of claim 4,
Wherein the concentration of the metal nano-rods in the ink is 1 to 60 wt%. 5. The method of claim 4,
The metal nano-rod may be formed of a metal such as gold (Au), silver (Ag), copper (Cu), nickel (Ni), iron (Fe), cobalt (Co), zinc (Zn), chromium (Cr) Nanorods, or combinations thereof. 5. The method of claim 4,
The printing may be performed by any suitable technique, such as inkjet printing, gravure printing, offset printing, screen printing or nano-imprint lithography, microarray printing and direct laser imaging laser imaging. < / RTI > 5. The method of claim 4,
Wherein the firing is performed at 100 to 250 < 0 > C.

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