KR101103515B1 - Printing method for conductive ink - Google Patents

Abstract

The present invention relates to a large-area printing method of conductive ink, the conductive ink using a printing method characterized in that to minimize the surface roughness of the surface according to the viscosity and surface tension of the ink and the printing surface roughness according to the dot on the printing plate It provides a way to print exactly where you want.
The manufacturing method of the pattern-shaped organic electrode of the present invention can be continuously produced by a printing method, and can be manufactured in a large area flexible transparent organic electrode having excellent transmittance, compared to the conventional metal oxide electrode using a vacuum process The economics and productivity of the process can be dramatically improved. In addition to the transparent electrode for display, the electrode manufactured by this electrode is an organic transistor electrode, wiring material, smart card. It is useful because it can be widely applied to various fields such as electrodes of antennas, cells and fuel cells, capacitors or inductors for PCBs, electromagnetic shielding, sensors, touch screens, and flexible displays.

Description

Printing method for conductive ink

The present invention relates to a printing method of minimizing surface roughness on a substrate by using a gravure printing method for printing a large area of a conductive ink.

As a method of manufacturing transparent electrodes widely used in electronic devices including flat panel displays, chemical vapor deposition using spontaneous metal oxides such as indium, tin, zinc, titanium, and cesium, especially indium tin oxide, sputtering, and reactive evaporation It is used. Since materials such as ITO are rare metals themselves, they are expensive, and in order to coat the substrate, process conditions such as vacuum conditions are difficult and expensive equipment is required, and a high heat treatment temperature of 200 ° C. or more is required. Expensive process costs must be invested.

In addition, in order to form the desired pattern, a subtractive method, that is, a resist film such as photolithography, a complex, expensive and waste-producing process such as exposure and etching, and an environmentally undesirable process are required. do. In the plastic substrate of the flexible display which can be folded and rolled like newspapers or thin magazines, which are needed in recent years, and are portable and easy to carry, the inorganic materials for transparent electrode in the form of metal oxides are the temperature conditions, It is difficult to apply because of low flexibility, complicated process and high cost.

In the display industry, photolithography, such as photolithography, is widely used to form various patterns, but it is an additive method of forming electrode patterns by using an eco-friendly process that reduces process cost and reduces waste by reducing process shortening and material loss. method) is being studied.

Conventionally, conductive ink has been applied to antenna, wiring, and fine line width printing using inkjet printing and gravure printing. However, in the large area printing part, it is almost insignificant or the surface roughness of the large area is formed high at the time of printing, so it is not applicable to the printing part of the electronic device.

That is, the surface roughness is severely formed when the conductive ink is printed in a large area by using a printing method on a substrate such as PET, PI, PEN, and this causes a phenomenon of reducing efficiency by surface roughness in device fabrication.

The present invention is to provide a method for improving the flexibility in printing by adjusting the viscosity of the ink, the surface tension to solve the surface roughness problem, and lowering the printing flexibility according to the dots and bow of the printing plate.

The present invention is a large-area gravure printing method using a conductive ink, the shape of the dot on the substrate is a diagonal form, the number of bows is 80 ~ 150 / inch, the conductive angle using a printed plate with the angle of 30 ~ 60 degrees A large area printing method, characterized in that for printing a large area of ink.

The present invention by adjusting the viscosity and surface tension of the conductive ink, and by adjusting the shape of the printing plate during gravure printing found that the surface roughness can be printed in a large area of 50nm or less, more specifically 1 ~ 50nm to the present invention Completed. The surface roughness is preferred because the surface roughness may be improved when the surface roughness is minimized as a factor affecting the subsequent process. If the surface roughness exceeds 50 nm, problems of deterioration of printability and nonuniformity of conductivity characteristics may occur in overlapping printing.

In the present invention, the substrate may be any type including a flexible plate-like polymer. Specifically, for example, a polymer film and paper selected from polypropylene, polyethylene terephthalate, polyethylene naphthalate, polyimide and the like can be used. More specifically, the present invention is characterized by using a flexible film-like substrate in the form of a roll.

The present invention is characterized in that the shape of the printing plate during the gravure printing is adjusted to the diagonal line has a merit that can transfer more ink by minimizing the formation of the wall between the dot and the dot when the dot has a dotted dot form, This improves the flatness due to a lot of ink on the surface to minimize the surface roughness.

In this case, by limiting the angles of the bow and diagonal lines of the printing platen to a specific range, printing with a surface roughness of 50 nm or less can be performed, and the post-process can be facilitated.

More specifically, when the number of bows is 80 to 150 / inch and the angle of inclination is 30 to 60 degrees, the surface roughness satisfies 50 nm or less, and when the number of bows is less than 80, ink is transferred excessively to form cotton. It is difficult to form an accurate shape due to the spread of the ink, and when the amount exceeds 150, the amount of ink transfer is small to form an uneven surface during surface formation. In addition, when the angle of the diagonal is less than 30 degrees, the same amount of ink is transferred, but ink spillage occurs in the opposite direction of the printing process due to the pressure of the roll, and when the angle exceeds 60 degrees, no face is formed even at the same viscosity. As it is formed, it brings about printability deterioration.

The conductive ink has a viscosity of 100 to 5000 cP (25 ° C.), a silver ink having a surface tension of 20 to 52 mN / m, or a conductive ink having a viscosity of 10 to 100 cP (25 ° C.) and a surface tension of 20 to 40 mN / m. Polymer ink can be used. The reason why the viscosity of the silver ink and the conductive ink is different is due to printability due to the solid content of each ink, and therefore, the viscosity is set differently. In addition, by applying an oblique form of plate making, both inks can minimize the surface roughness of the surface.

More specifically, in the present invention, the silver ink includes a solvent such that the average particle size of the silver nanoparticles having a mean particle size of 20 to 100 nm is 30 to 70 wt%, 5 to 15 wt%, and 100 wt% of the polymeric binder. In the above range can be prepared a silver ink having a viscosity of 100 ~ 5000 cP (25 ℃), the surface tension of 20 ~ 52mN / m. When the viscosity is less than 100 cP (25 ° C), a bleeding phenomenon occurs during printing, and when the viscosity exceeds 5000 cP (25 ° C), it is preferable to use within the above range because a dot form due to high viscosity appears. In addition, when the surface tension is less than 20mN / m, the property of contact with the substrate is good to form a pattern that spreads when the pattern is formed, and when it exceeds 52mN / m, the ink tends to fall due to the property of contact with the substrate. Appears and brings about deterioration of printability.

The polymer binder is preferably used because at least one selected from polyvinylpyrrolidone, polyvinyl alcohol, and polyacrylate improves adhesion and surface flatness.

The solvent is preferable to use any one or more selected from water, ethylene glycol, isopropyl alcohol, ethanol, hexyl alcohol, lauryl alcohol and the like because it is necessary to control the viscosity and surface tension.

When the silver ink is used, printing with a surface roughness of 50 nm or less is possible.

The conductive polymer ink includes a solvent to satisfy 10 to 50% by weight of the conductive polymer, 0.1 to 2% by weight and 100% by weight of the silane coupling agent. In the above range, a conductive polymer ink having a viscosity of 10 to 100 cP (25 ° C.) and a surface tension of 20 to 40 mN / m may be prepared. If the viscosity is less than 10 cP (25 ° C), the viscosity is low, the surface is formed by smearing, if it exceeds 100 cP (25 ° C) it is preferable to use in the above range because wrinkles (wrinkling) occurs on the printing surface. In addition, if the surface tension is less than 20mN / m, the contact with the substrate is excellent, the surface is formed without spreading accurately, if the surface tension exceeds 40mN / m, the contact with the substrate is poor, the ink aggregates after printing Phenomenon occurs.

The conductive polymer is preferably poly (3,4-ethylenedioxythiophene) (PEDOP), polyaniline, polypyrrole, etc., because it can be used as an electrode, wiring, or electrochromic device.

The solvent is preferably used because one or more selected from water, ethylene glycol, isopropyl alcohol, ethanol, enmethyltupyrrolidone, hexyl alcohol, lauryl alcohol, etc. can be used to control the viscosity and surface tension.

The silane coupling agent is allyl triethoxy silane, vinyl triethoxy silane, vinyl trimethoxy silane, 3-aminopropyltriethoxy silane, 3-aminopropyltrimethoxy silane, 3-mercaptopropyltrimethoxysilane It is preferable to use any one or more selected from because it increases the adhesion.

When the conductive polymer ink is used, printing with a surface roughness of 10 nm or less is possible.

The present invention also includes an electronic device printed by the printing method.

The electronic device may include an antenna, a wiring, a fine line width, an electrode, an electronic circuit, an electrochromic device, and the like.

The present invention is possible to print a large area by changing the viscosity and surface tension of the conductive ink and the shape of the bow and dots of the printing plate, it is determined that the large area printing will have a significant effect on the manufacturing of the printing device.

In addition, as the solar cell market expands in the future, it is necessary to print a large area of electronic ink, and the present invention may solve the problem.

1 illustrates an example of a printing plate making with a dotted dot-shaped dot according to the present invention.

In the present invention, the conductive ink was printed using a gravure printing method for large area printing.

The surface roughness according to the following example was measured by using an AFM (Atomic Force Microscope), 3D surface profiler (roughness).

Example 1

The conductive ink was printed on the polyethylene terephthalate film (thickness 75 mu m) in a large area.

Conductive ink is mixed with 10% by weight of PEDOT, 48% by weight of distilled water, 30% by weight of ethylene glycol, 10% by weight of isopropyl alcohol (IPA), 2% by weight of 3-aminopropyltrimethoxy silane, viscosity of 15 cP, surface tension A conductive ink of 25.4 mN / m was prepared.

The printing was carried out gravure printing using a printing plate with a dotted line, the number of bows is 80 / inch, the angle of the diagonal is 30 degrees.

As a result of measuring the surface roughness of the printed surface, it was confirmed that the surface roughness was formed about 7 nm.

[Example 2]

The conductive ink was printed on the polyethylene terephthalate film (thickness 75 mu m) in a large area.

The conductive ink was mixed with 10% by weight of PEDOT, 48% by weight of distilled water, 35% by weight of ethylene glycol, 5% by weight of isopropyl alcohol (IPA), and 2% by weight of 3-aminopropyltrimethoxy silane to obtain a viscosity of 20 cP and a surface. A conductive ink having a tension of 26 mN / m was prepared.

The printing was carried out gravure printing using a printing plate with a dotted line, the number of bows is 80 / inch, the angle of the diagonal is 30 degrees.

As a result of measuring the surface roughness of the printed surface, it was confirmed that the surface roughness was formed about 7.5 nm.

Example 3

The conductive ink was printed on the polyethylene terephthalate film (thickness 75 mu m) in a large area.

The conductive ink was mixed with 10% by weight of PEDOT, 48% by weight of distilled water, and 2% by weight of 40% by weight of ethylene glycol 3-aminopropyltrimethoxy silane to prepare a conductive ink having a viscosity of 25 cP and a surface tension of 30 mN / m.

The printing was carried out gravure printing using a printing plate with a dotted line, the number of bows is 80 / inch, the angle of the diagonal is 30 degrees.

As a result of measuring the surface roughness of the printed surface, it was confirmed that the surface roughness was formed about 7.5 nm.

Example 4

The conductive ink was printed on the polyethylene terephthalate film (thickness 75 mu m) in a large area.

The conductive ink was mixed with 30% by weight of PEDOT, 28% by weight of distilled water, and 2% by weight of 40% by weight of ethylene glycol 3-aminopropyltrimethoxy silane to prepare a conductive ink having a viscosity of 100 cP and a surface tension of 40 mN / m.

The printing was carried out gravure printing using a printing plate with a dotted line, the number of bows is 80 / inch, the angle of the diagonal is 30 degrees.

As a result of measuring the surface roughness of the printed surface, it was confirmed that the surface roughness was formed about 9 nm.

Example 5

The conductive ink was printed on the polyethylene terephthalate film (thickness 75 mu m) in a large area.

The conductive ink was prepared by mixing 30 wt% silver particles, 20 wt% distilled water, 40 wt% ethylene glycol, and 10 wt% IPA to prepare a conductive ink having a viscosity of 100 cP and a surface tension of 40 mN / m.

The printing was carried out gravure printing using a printing plate with a dotted line, the number of bows is 80 / inch, the angle of the diagonal is 30 degrees.

As a result of measuring the surface roughness of the printed surface, it was confirmed that the surface roughness was formed about 30 nm.

Example 6

The conductive ink was printed on the polyethylene terephthalate film (thickness 75 mu m) in a large area.

The conductive ink was mixed with 40% by weight of silver particles, 20% by weight of distilled water, 30% by weight of ethylene glycol, and 10% by weight of isopropyl alcohol (IPA) to prepare a conductive ink having a viscosity of 500 cP and a surface tension of 38 mN / m.

The printing was carried out gravure printing using a printing plate with a dotted line, the number of bows is 80 / inch, the angle of the diagonal is 30 degrees.

As a result of measuring the surface roughness of the printed surface, it was confirmed that the surface roughness was formed about 40 nm.

Example 7

The conductive ink was printed on the polyethylene terephthalate film (thickness 75 mu m) in a large area.

The conductive ink was mixed with 60 wt% silver particles, 25 wt% distilled water, and 15 wt% ethylene glycol to prepare a conductive ink having a viscosity of 5000 cP and a surface tension of 52 mN / m.

The printing was carried out gravure printing using a printing plate with a dotted line, the number of bows is 80 / inch, the angle of the diagonal is 30 degrees.

As a result of measuring the surface roughness of the printed surface, it was confirmed that the surface roughness was formed about 45 nm.

Comparative Example 1

The same conductive ink as in Example 1 was used, but the printing plate was used as the ink plate with a number of bows of 70 pieces / inch and an oblique angle of 30 degrees.

As a result of measuring the surface roughness of the printed surface, it was confirmed that the surface roughness was formed about 30 nm, but the surface was formed by smearing.

Comparative Example 2

The same conductive ink as in Example 1 was used, but the printing plate was used as an ink plate with a number of bows of 175 / inch and an oblique angle of 30 degrees.

As a result of measuring the surface roughness of the printed surface, it was confirmed that the surface roughness was formed about 55 nm.

Comparative Example 3

The same conductive ink as in Example 1 was used, but the printing plate was used as the ink plate with a number of bows of 90 pieces / inch and an oblique angle of 10 degrees.

As a result of measuring the surface roughness of the printed surface, it was confirmed that the surface roughness was formed about 8 nm, but the surface was formed by smearing.

[Comparative Example 4]

The same conductive ink as in Example 1 was used, but the printing plate was used as the ink plate with the number of bows of 90 pieces / inch and the diagonal angle of 70 degrees.

As a result of measuring the surface roughness of the printed surface, it was confirmed that the surface roughness was formed about 70 nm.

[Comparative Example 5]

The conductive ink was printed on the polyethylene terephthalate film (thickness 75 mu m) in a large area.

The conductive ink was mixed with 35% by weight of PEDOT, 28% by weight of distilled water, and 2% by weight of 35% by weight of ethylene glycol 3-aminopropyltrimethoxy silane to prepare a conductive ink having a viscosity of 150 cP and a surface tension of 42 mN / m.

The printing was carried out gravure printing using a printing plate with a dotted line, the number of bows is 80 / inch, the angle of the diagonal is 30 degrees.

As a result of measuring the surface roughness of the printed surface, it was confirmed that the surface roughness was formed about 20 nm.

[Comparative Example 6]

Using the same ink plate as in Example 4, the content of silver was mixed 60% by weight, distilled water 20% by weight, ethylene glycol 20% by weight to prepare a viscosity of 5500cP, surface tension 50mN / m and printed.

As a result of measuring the surface roughness of the printed surface, it was confirmed that the surface roughness was formed about 200 nm.

Claims (9)

A large-area gravure printing method using conductive ink, wherein the dot pattern is diagonally formed on the substrate, and the conductive ink is applied by using a printing plate having 80 to 150 bows per inch and the diagonal angle of 30 to 60 degrees. A large area printing method, characterized in that for printing in area. The method of claim 1,
The conductive ink has a viscosity of 100 ~ 5000 cP (25 ℃), a surface ink of 20 ~ 52mN / m silver ink or a viscosity of 10 ~ 100 cP, the surface tension of 20 ~ 40mN / m using a conductive polymer ink Large area printing method to do. The method of claim 2,
The silver ink is a large-area printing method comprising a solvent such that the average particle diameter of 20 to 100 nm silver nanoparticles 30 to 70% by weight, polymer binder 5-15% by weight and 100% by weight. The method of claim 3, wherein
The polymer binder is any one or more selected from polyvinylpyrrolidone, polyvinyl alcohol, polyacrylate, and the solvent is any one or more selected from water, ethylene glycol and isopropyl alcohol. The method of claim 2,
The conductive polymer ink is a large area printing method comprising a solvent to satisfy the conductive polymer 10 to 50% by weight, 0.1 to 2% by weight and 100% by weight of the silane coupling agent. 6. The method of claim 5,
The conductive polymer is poly (3,4-ethylenedioxythiophene), polyaniline, polypyrrole, the solvent is at least one selected from water, ethylene glycol and isopropyl alcohol, and the silane coupling agent is allyltriethoxy silane, vinyl A large-area printing method comprising at least one selected from triethoxy silane, vinyltrimethoxy silane, 3-aminopropyltriethoxy silane, 3-aminopropyltrimethoxy silane, and 3-mercaptopropyltrimethoxysilane. The method of claim 1,
The substrate is a large area printing method selected from polypropylene, polyethylene terephthalate, polyethylene naphthalate, polyimide. delete delete

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