KR102213925B1 - Ink composition for flash light sintering comprising silica particles - Google Patents

Abstract

The present invention relates to an ink composition for flash light sintering comprising silica particles, and more particularly, to an ink composition for flash light sintering, which forms a conductive pattern such as a metal mesh by flash light sintering.

Description

[Ink composition for flash light sintering comprising silica particles]

The present invention relates to an ink composition for photosintering to form a conductive pattern such as a metal mesh by photosintering.

Transparent electrodes that transmit light in the visible region and have a transparent property and are electrically conductive are widely used as electrodes for flat displays such as LCD (liguid crystal display) and OLED (organic electroluminence device), touch screen panels, and lighting.

Although indium tin oxide (ITO) was mainly used as the material for such a transparent electrode, there is a problem of low electrical conductivity due to the problem of increasing unit cost, high resistance, and low tensile strength due to external force easily cracking, and in particular, due to weak mechanical properties, conventional glass substrates However, it is difficult to apply it on a flexible substrate, so attempts to replace it have been made everywhere.

Silver nanowires, graphene, and metal mesh are being used as substitutes for indium tin oxide (ITO). Among them, metal mesh is a method in which a metal with a low resistance value on a substrate forms a thin film of silver or copper in a square pattern.It is attracting attention as an alternative to the ITO method, which has problems such as shortage of supply and depletion of indium as a raw material mineral. Receiving.

Metal mesh has the advantage of being able to develop a flexible display due to its low resistance, making it easy to apply a touch panel to a large screen, and having good ductility. In addition, it is effective in shortening the process because it is easy to supply and demand metal and can simultaneously form the sensor electrode part and the narrow bezel part using a paste composition.

The metal mesh includes a method of depositing copper by etching or sputtering, or a method of coating silver ink. However, it is difficult to apply to a large-area substrate, the manufacturing cost is high, and the process time is long, so research to alternative this is in progress. Among them, copper ink is applied, but high heat is required as an oxide film of copper to sinter copper, and the deformation of the flexible polymer film was not prevented due to the heat. In addition, there is a problem in adhesion to the substrate and electrode, and the adhesion and resistance change is not good even in reliability (high temperature, high humidity).

On the other hand, the photo-sintering process is a process of densifying particles by photothermal effect by applying an instantaneous light pulse, and the metal nano-ink pattern printed on the flexible substrate can be sintered in a very short time in a room temperature atmosphere and atmospheric pressure conditions. This photo-sintering process can be applied to a large-area substrate, as well as high-speed sintering at room temperature in the atmosphere, thereby improving productivity according to mass production.

Republic of Korea Patent Application Publication No. 2014-0046012: Composition set, conductive substrate and method for manufacturing the same, and conductive adhesive composition Republic of Korea Patent Publication No. 2014-0082810: A method of forming a conductive pattern and a composition for forming a conductive pattern by light irradiation or microwave heating Republic of Korea Patent Publication No. 2016-0077410: Optical sintering ink composition and method of manufacturing a wiring board using the same

An object of the present invention is to provide an ink composition for photo-sintering capable of manufacturing a copper electrode having excellent adhesion and a remarkably improved resistance change rate even in an environment of high temperature and high humidity.

The present invention is a copper particle coated with one selected from the group consisting of silver (Ag), nickel (Ni), palladium (Pd), gold (Au), and platinum (Pt); A binder containing silica particles and a polyester resin; Urethane additives; Dispersant; And it can provide an ink composition for photosintering containing a solvent.

When the ink composition for photosintering of the present invention is used, it is possible to sinter in a short time at room temperature and pressure, and has excellent adhesion to flexible polymer films, and has excellent resistance change rate and adhesion in high temperature and high humidity environments. Is possible.

Hereinafter, an ink composition for photosintering according to an embodiment will be described.

The ink composition for photosintering according to an embodiment includes copper particles, a binder, a urethane-based additive, a dispersant, and a solvent.

The copper particles are sintered to form a conductive pattern when irradiated with light on a printed pattern formed using an ink composition, and composed of silver (Ag), nickel (Ni), palladium (Pd), gold (Au), and platinum (Pt). Copper particles coated with one selected from the group are possible.

The particle diameter of the copper particles is preferably 100 nm to 10 μm. When the particle diameter of the copper particles is less than the above range, the specific surface area increases and oxidation is easily performed. When the particle diameter exceeds the above range, it is difficult to implement a fine pattern.

According to one embodiment, the copper particles may be included in an amount of 70 wt% to 80 wt% based on the total weight of the photosintering ink composition. If the content of the copper particles is less than 70 wt%, it is difficult to manufacture a dense conductive pattern. On the contrary, if the content of the copper particles exceeds 80 wt%, it is difficult to perform a smooth coating operation for pattern formation with an increased viscosity.

The binder is a material that binds copper particles when forming a wiring pattern using an ink composition for optical sintering, and functions to maintain excellent printability and high aspect ratio of the wiring pattern.

According to one embodiment, the binder includes silica particles and a polyester resin. At this time, the average particle diameter of the silica particles is preferably 30 to 3000 nm, preferably 35 to 1000 nm. The silica particles may be included in an amount of 3 to 10 parts by weight based on 100 parts by weight of the polyester resin.

The binder may be included in an amount of 10 to 12 wt% based on the total weight of the photosintering ink composition. If the content of the binder is less than the above range, sintering of the copper particles is not well performed. Conversely, if the content of the binder exceeds the above range, sintering of the copper particles may be hindered by the binder.

The polyester resin has a glass transition temperature (Tg) of 50° C. and a molecular weight of 20000 Mn or more. If the glass transition temperature is higher than 50° C., adhesion after light sintering is poor, and if the temperature is too low than 50° C., the stickiness is high and the coating property is poor, so that the ink cannot be properly filled, and cracks appear after photo-sintering.

The urethane-based additive enhances adhesion to the flexible polymer film and has excellent heat resistance, thereby minimizing the deformation of the film.

According to one embodiment, the urethane-based additive is represented by the following Formula 1:

[Formula 1]

(In Formula 1,

R is hydrogen; A substituted or unsubstituted C1-C30 aliphatic alkyl group, an alicyclic alkyl group, an aryl group, or an aralkyl group; High molecular compound group; Heterocyclic compound group; Or their derivatives.)

R is specifically, for example, hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl, hexyl, ethylhexyl, heptyl, octyl, isooctyl, nonyl, decyl, dodecyl, hexadecyl, octa Decyl, docodecyl, cyclopropyl, cyclopentyl, cyclohexyl, allyl, hydroxy, methoxy, hydroxyethyl, methoxyethyl, 2-hydroxy propyl, methoxypropyl, cyanoethyl, ethoxy, butoxy, Hexyloxy, methoxyethoxyethyl, methoxyethoxyethoxyethyl, hexamethyleneimine, foline, piperidine, piperazine, ethylenediamine, propylenediamine, hexamethylenediamine, triethylenediamine, pyrrole, imidazole , Pyridine, carboxymethyl, trimethoxysilylpropyl, triethoxysilylpropyl, phenyl, methoxyphenyl, cyanophenyl, phenoxy, tolyl, benzyl and derivatives thereof, and high molecular compounds such as polyallylamine or polyethyleneimine And derivatives thereof, and the like, but is not particularly limited thereto.

At this time, the urethane-based additive is 2 to 4 wt% of the total content of the photo-sintering ink composition. If the content of the additive is less than 2 wt%, adhesion is lowered, resulting in reliability problems. Conversely, if the content is more than 4 wt%, the resistance increases during light sintering and cracks occur in the coating film.

The dispersant uniformly disperses the copper particles in the ink composition for photo-sintering, thereby suppressing the generation of pores in the conductive pattern formed by photo-sintering. The dispersant may provide desired physical properties and coating properties by selecting one having good compatibility with the copper particle surface and excellent compatibility between the compositions. According to one embodiment, the dispersant may be a deagglomerated polymer type (polyurethane type, polyacrylic type), low molecular type (fatty acid type, phosphate ester type), or the like.

The dispersant may be included in an amount of 1 to 3 wt% based on the total weight of the photosintering ink composition. If the content of the dispersant is less than the above range, the effect of the addition is insignificant, and if it exceeds the above range, densification between copper particles may be inhibited by the binder.

The ink composition for photosintering according to an embodiment may include a solvent such as a known organic solvent and an aqueous solvent to impart wettability during dispersion and coating of copper particles, and wettability during continuous printing. Water as the solvent; Alcohols such as methanol, ethanol, and isopropyl alcohol; Ketones such as methyl ethyl ketone and methyl isobutyl ketone; Pyrrolidines such as N-methylpyrrolidone, esters such as ethyl acetate; Aromatic esters such as benzyl acetate; Linear and/or branched hydrocarbons such as dimethoxyethane and 1-chlorobutane; Glycol ethers (cellosolve) such as dipropylene glycol methyl ether, ethyl cellosolve acetate, and butyl cellosolve acetate; And one or more selected from the group consisting of a mixture thereof may be used.

The solvent may be included in the balance to satisfy 100% by weight of the total ink composition for photosintering.

In addition, according to one embodiment, the ink composition for light sintering may contain known additives (antifoaming agents, surface modifiers, thixotropic agents, etc.).

The optical sintering ink composition may be formed on a substrate with a printed pattern of an arbitrary shape, and light irradiation may be performed on the printed pattern to generate a sintered body of copper, thereby forming a conductive pattern.

Hereinafter, preferred examples and experimental examples of the present invention will be described. The following examples and experimental examples are described for the purpose of more clearly expressing the present invention, but the contents of the present invention are not limited to the following examples.

Manufacturing example 1: Binder preparation

In a round flask, add 5500 g of Dipropylene Glycol Methyl Ether and 50 g of DI-water, heat it while maintaining the stirring at 500 rpm so that the temperature of the solution is maintained at 50 ℃, and then 20 g of AEROSIL®200 sequentially. And polyester resin (Mn 20,000, Tg 50 ℃) 380 g was added and stirred for 4 hours. After 4 hours, stirring was stopped and maintained for 1 hour to remove air bubbles in the binder to prepare a binder.

Manufacturing example 2: Preparation of urethane additives

10 g of ethylene glycol monobutyl ether was added to a round flask, heated while maintaining the stirring at 500 rpm so that the temperature of the solution was maintained at 40° C., and then 10 g of titanate coupler (LICA 01) was added and maintained for 2 hours. Then, 80 g of a block isocyanate compound (Baxenden Chemical BI 201, water based blocked isocyanate) was added and stirred for 2 hours. At this time, the blocking agent of the blocked isocyanate compound was 3,4-dimethyl pyrazole.

Example 1 to 6 and Comparative example 1 to 8: Light sintering Preparation of ink composition

1 wt% of YK company disperbyk161 was added as a dispersant to the mixture of the binder and the additive in the composition ratio as shown in Table 1 below, and the first dispersion was mixed using a Paste mixer, and then particles D50: 80 wt% of silver coated copper particles of 2 µm In addition, the remaining DOWANOL DPM (Dipropylene Glycol Methyl Ether) solvent was added in a composition ratio as shown in Table 1 so that the total content was 100 wt%, and a secondary dispersion was prepared using a 3 roll mill.

In Comparative Example 7, 1 wt% of a dispersant was added to the mixture of the first binder and the melamine resin prepared in Example 1 in the composition ratio shown in the table below, and the first dispersion was mixed using a Paste mixer, and the particles D50: 2 µm The remaining DOWANOL DPM (Dipropylene Glycol Methyl Ether) solvent was added at a composition ratio as shown in Table 1 below so that 80 wt% of silver-coated copper particles were added to the total content of 100 wt%, and a secondary dispersion was prepared using a 3roll mill.

Comparative Example 8 was prepared in the same manner as in Comparative Example 7 by adding the binder and hydrogenated rosin prepared in Example 1 in the composition ratio shown in Table 1.

division bookbinder additive Dispersant menstruum Copper particles Example 1 Manufacturing Example 1
11 wt% Manufacturing Example 2
2 wt% 1 wt% 6 wt% 80 wt% Example 2 Manufacturing Example 1
11 wt% Manufacturing Example 2
3 wt% 1 wt% 5 wt% 80 wt% Example 3 Manufacturing Example 1
11 wt% Manufacturing Example 2
4 wt% 1 wt% 4 wt% 80 wt% Example 4 Manufacturing Example 1
12 wt% Manufacturing Example 2
2 wt% 1 wt% 5 wt% 80 wt% Example 5 Manufacturing Example 1
12 wt% Manufacturing Example 2
3 wt% 1 wt% 4 wt% 80 wt% Example 6 Manufacturing Example 1
12 wt% Manufacturing Example 2
4 wt% 1 wt% 3 wt% 80 wt% Comparative Example 1 Manufacturing Example 1
12 wt% - 1 wt% 7 wt% 80 wt% Comparative Example 2 Tg below 40 ℃ binder
10 wt% Manufacturing Example 2
2 wt% 1 wt% 7 wt% 80 wt% Comparative Example 3 Acrylate resin
10 wt% Manufacturing Example 2
2 wt% 1 wt% 7 wt% 80 wt% Comparative Example 4 Phenoxy resin
10 wt% Manufacturing Example 2
2 wt% 1 wt% 7 wt% 80 wt% Comparative Example 5 Manufacturing Example 1
10 wt% Manufacturing Example 2
1 wt% 1 wt% 8 wt% 80 wt% Comparative Example 6 Manufacturing Example 1
10 wt% Manufacturing Example 2
5 wt% 1 wt% 4 wt% 80 wt% Comparative Example 7 Manufacturing Example 1
10 wt% Melamine resin
2 wt% 1 wt% 7 wt% 80 wt% Comparative Example 8 Manufacturing Example 1
10 wt% Hydrogenated rosin
2 wt% 1 wt% 7 wt% 80 wt%

Experimental example 1: Evaluation of properties of the ink composition

The optical sintering ink compositions prepared in Examples 1 to 6 and Comparative Examples 1 to 8 were patterned with a PET-based intaglio using an imprinting equipment, and the line width was printed on a film of 2 to 9 μm, and then 80 After drying for 5 minutes in a hot air oven set at a temperature of °C, sintering was performed with light energy of 7J and 10ms using a light sintering equipment.

The surface resistance was measured 5 times using a surface resistance meter (SIMCO, ST-4), and then the average was obtained, and the adhesion test was performed in a cross-cut test according to ASTM D3359 standard. Thereafter, a 3M tape (V610) test was carried out to obtain it, and ASTM D3359 standard first selects a portion of the coating film to be tested, and then performs a cross-cut test.

In this experimental example, cross-cuts were performed at intervals of 1 mm. After attaching a tape, rubbing it with an eraser to adhere the tate to the coating film, it was quickly ripped to confirm, and the evaluation method was shown in 6 steps: 5B> 4B> 3B> 2B> 1B> 0B This is excellent). In the same way, after leaving for 10 days in an environment of high temperature and high humidity, the rate of change of resistance and adhesion were measured. The results are shown in Tables 2 and 3 below, respectively.

Referring to Tables 2 and 3, the ink composition according to the present invention has excellent adhesion to the flexible polymer film, and resistance change and adhesion in high temperature and high humidity environments are also excellent.

Claims (7)

Copper particles coated with one selected from the group consisting of silver (Ag), nickel (Ni), palladium (Pd), gold (Au), and platinum (Pt);
A binder containing silica particles and a polyester resin;
Urethane additives;
Dispersant; And
An ink composition for photosintering containing a solvent. The method of claim 1, wherein the silica particles are
The optical sintering ink composition that is contained in an amount of 3 to 10 parts by weight based on 100 parts by weight of the polyester resin. The method of claim 1, wherein the average particle diameter of the silica particles is
The ink composition for light sintering of 30 to 3000 nm. The method of claim 1, wherein the polyester resin is
The glass transition temperature is 50 ℃ to the ink composition for light sintering. The method of claim 1, wherein the content of the binder is
The ink composition for photosintering of 10 to 12% by weight based on the total weight of the ink composition for photosintering. The method of claim 1, wherein the urethane-based additive
The optical sintering ink composition represented by the following Formula 1:
[Formula 1]

(In Formula 1,
R is hydrogen; A substituted or unsubstituted C1-C30 aliphatic alkyl group, an alicyclic alkyl group, an aryl group, or an aralkyl group; Polyallylamine; Polyethyleneimine; Heterocyclic compound group; Or their derivatives.) The method of claim 1, wherein the content of the urethane-based additive is
The light sintering ink composition is 2 to 4% by weight based on the total weight of the light sintering ink composition.