KR100727760B1 - Conductive metal oxides dispersion using ?-diketone as dispersant and anti-static, conductive coating layer for using the same - Google Patents

Abstract

The present invention provides a metal oxide dispersion comprising a β-diketone as a dispersant in a metal oxide dispersion containing a metal oxide and an organic solvent. The present invention also provides a front panel for a display device in which a transparent conductive layer is formed by coating a metal oxide dispersion using β-diketone as a dispersant on a transparent substrate.

The metal oxide dispersion of the present invention exhibits improved dispersibility, surface resistance of less than 5 × 10 ⁴ Ω / □, reflectance of less than 1%, high light transmittance as well as whitening phenomenon without deterioration of electrical conductivity. It is possible to provide an electromagnetic shielding and antistatic coating film having a clean appearance.

β-diketone, dispersion, metal oxide, dispersion solvent, coating film, transparent conductive layer

Description

Metal oxide dispersion using beta-diketone as a dispersant and an antistatic conductive coating film using the same {CONDUCTIVE METAL OXIDES DISPERSION USING

1 is a graph showing the change in secondary particle size according to the storage time of the metal oxide dispersion liquid using beta-diketone as a dispersant by varying the amount used in Example 9.

FIG. 2 is a graph showing secondary particle size change with storage time of a metal oxide dispersion liquid using titanium coupling as a dispersant with varying amounts used in Comparative Example 2. FIG.

This invention relates to the metal oxide dispersion liquid characterized by using (beta) -diketone as a dispersing agent in the metal oxide dispersion liquid containing a metal oxide and an organic solvent. When the metal oxide is a conductive metal oxide, the metal oxide dispersion is useful as a metal oxide coating liquid for forming an antistatic conductive coating film on a front panel such as a display such as a CRT.

Recently, the public's interest is increasing in various problems such as malfunction of various peripheral devices generated by electromagnetic waves leaking from various VDT (Video Display Terminal) equipment and destruction of human immune system. As an example of such a VDT equipment, a cathode ray tube (called the CRT) of a television or a computer needs to prevent electromagnetic leakage and damage such as adhesion of dust or electric shock due to charging of the CRT screen.

In the case of magnetic field leakage, it is mostly prevented by changing the shape of the deflection coil, and the charging phenomenon of the screen and the leakage of the electric field can be solved by coating a material having high electrical conductivity on the transparent substrate. That is, by forming a conductive layer having electrical conductivity on the surface of the transparent substrate constituting the front panel for the display device, it is easy to move the static charge induced on the surface of the transparent substrate by the voltage applied to the inside of the display device, so that the static charge is not accumulated. You can do that. In order to prevent the charge, a coating layer having a surface resistance of 10 ⁴ to 10 ⁸ Ω / square is required, and a surface resistance of 10 ³ Ω / □ or less is required for the purpose of electric field blocking.

The main component constituting the transparent conductive coating film may be selected from the group consisting of metal oxides such as indium oxide, tin added indium oxide, tin oxide, antimony added tin oxide, aluminum added zinc oxide and titanium oxide, and a coating layer such as CRT Indium tin oxide (ITO) is known to have the most excellent conductivity and transparency as a metal oxide for production.

As a method for forming the transparent conductive coating film, a method such as vacuum deposition and sputtering of metal oxides may be applied, but there is a problem that the coating process is complicated and the manufacturing cost of the coating film is increased due to the use of various vacuum equipment.

On the other hand, as a method for forming a coating film having electrical conductivity and transparency, a coating liquid containing transparent conductive fine particles on the transparent substrate as a first layer is applied by a spin coating method, and continuously prevented reflection including silicate (SiO ₂ ) There is a method of applying the coating liquid and anti-glare coating liquid to the second layer and the third layer by spin coating and spray coating, which is easier and more suitable for mass production.

In particular, as a coating liquid for realizing a low resistance coating film for electric field blocking, a technique using a dispersion containing metal fine particles has been proposed, and the surface resistance of a coating film obtained from a dispersion using fine particles of metal oxide is 10 ⁴ Ω. Although relatively high at /, it was possible to close the field leakage sufficiently by using a calibration circuit.

As a method for preparing a stable transparent conductive coating liquid by dispersing such a metal oxide in an organic solvent such as alcohol, a method using various titanium coupling agents, aluminum coupling agents, silicone coupling agents and the like as a dispersant is disclosed in Japanese Patent Application Laid-Open No. 7-242842. As presented in

The coupling agent chemically reacts with the hydroxyl group present on the surface of the metal oxide, such as tin indium, and adsorbs on the surface of the particle, and the adsorbed molecular layer provides a mutually repelling force between the particles to provide a stable coating solution that does not settle by gravity. To manufacture.                         

However, the coupling agent has a problem that the unit price is expensive and has a molecular weight of several hundred g / mol and is not completely removed even at a high temperature, so that the coupling agent remains on the surface of the metal oxide applied to the transparent substrate to act as an insulating layer after coating. Thus, when utilizing the coupling agent as a dispersant to stabilize the metal oxide can cause a serious problem that the electrical resistance of the coated transparent conductive layer is increased.

In addition, in the case of the coupling agent, when a predetermined content or more is added to the dispersion, a comb pattern is formed on the surface of the coating film, thereby greatly reducing the appearance of the coating surface. In addition, when a certain amount or more of the coupling agent is added to the dispersion of the metal oxide, the storage stability of the dispersion is deteriorated by the desorption agglomeration phenomenon, thereby causing the aggregation of the metal oxide particles.

The present invention intends to use a β-diketone compound as a dispersant to provide a metal oxide dispersion having improved dispersion stability in an organic solvent. In addition, the present invention intends to use a β-diketone-based compound having a boiling point lower than the firing temperature of the firing process performed after applying the metal oxide dispersion to the substrate in order to solve the problems of the prior art due to the dispersant residue. . When the antistatic transparent conductive film such as CRT is formed from the metal oxide dispersion using the dispersant, all the dispersants are evaporated during the firing process, thereby deteriorating the appearance such as deterioration of electrical conductivity due to the dispersant residue or coating whitening. The problem can be solved.

The present invention provides a metal oxide dispersion comprising a β-diketone as a dispersant in a metal oxide dispersion containing a metal oxide and an organic solvent. The β-diketone dispersant is preferably a β-diketone compound having a boiling point lower than the firing temperature of the coating film coated with the metal oxide dispersion.

The present invention also provides a front panel for a display device in which a transparent conductive layer is formed by coating a metal oxide dispersion using β-diketone as a dispersant on a transparent substrate. The front panel for the display device is a transparent substrate; Transparent conductive layer; Anti-reflective coating layer; And anti-glare coating layers.

Hereinafter, the present invention will be described in more detail.

The metal oxide dispersion liquid of this invention is formed by mixing the organic solvent, such as a metal oxide and alcohol, and the dispersing agent of (beta) -diketone.

In the metal oxide dispersion of the present invention, the metal oxide is preferably a conductive metal oxide to form an antistatic coating film. Examples of the metal oxide dispersion include, but are not limited to, tin indium oxide (ITO), antimony tin oxide (ATO), and antimony addition oxide. Zinc (AZO) and the like. The illustrated conductive metal oxide may impart permeability and conductivity to the coating layer including the same, and may act as a transparent electromagnetic shielding film.

The preferred average particle diameter of the metal oxide is 70 to 130 nm. If it is less than 70 nm, there is a problem of deterioration of conductivity, and if it exceeds 130 nm, there is a problem that whitening occurs during coating.

The present invention is characterized by using β-diketone as the dispersant in the metal oxide dispersion.

β-diketone is a compound having two carbonyl groups separated by intermediate carbon.

The mechanism of action of the β-diketone as a dispersant in the metal oxide dispersion is as follows.

When the metal oxide is mixed with the β-diketone and the organic solvent, the lone pair of electrons in the oxygen of the carbonyl group of the β-diketone is chemically bonded to the metal. In this case, since 2 mol of an oxygen atom of a carbonyl group is present per mol of the β-diketone molecule, a complex compound of a metal oxide and β-diketone having a very strong chemical bond is formed. The binding layer of β-diketone formed on the surface of the metal oxide particles acts to block the van der Waals Force acting between the particles to prevent the aggregation of particles by the attraction and gravity between particles.

In the present invention using β-diketone having a boiling point lower than the firing temperature of the transparent conductive coating layer as a dispersant of the metal oxide dispersion, the content of the dispersant used is different from that of the prior art using a coupling agent. It exhibits an advantage of hardly affecting the electrical conductivity of the coating layer and the appearance of the film, and β-diketone does not act as a resistance to the transparent conductive coating layer because it evaporates mostly during firing of the transparent conductive coating layer.

For example, β-diketones such as acetylacetone having a boiling point of less than 200 ° C. adsorb on the surface of conductive metal oxides such as tin indium oxide (ITO) to act as a dispersant in an organic solvent, and unlike the coupling agent, the firing temperature of the coating layer It is nearly 100% evaporated at 200 ℃. For example, the calcination temperature of a general transparent conductive film is 200 ° C, whereas acetylacetone has a boiling point of 140 ° C, which is a lower temperature.

Preferred examples of β-diketone compounds include 2,4-pentanedione (acetylacetone), 3-methyl-2,4-pentanedione, 3-isopropyl-2,4-pentanedione, 2,2-dimethyl-3 , 5-hexanedione and the like, and preferably have a relatively low boiling point and low molecular weight. For example, the boiling point of the β-diketone compound is preferably 200 ° C. or lower, and the molecular weight is preferably 70 to 150. Therefore, it is particularly preferable to use acetylacetone.

The content of β-diketone compound in the metal oxide dispersion is preferably 0.5 to 20 parts by weight based on 100 parts by weight of the metal oxide solids. If it is less than 0.5 part by weight, the dispersibility is lowered, and if it exceeds 20 parts by weight, drying during coating is slowed or conductivity is lowered.

In addition, when the content of the dispersant is within the above range, it does not affect the storage stability of the prepared coating liquid or the electrical, optical properties, appearance, etc. of the coating layer, but it is possible to prepare a stable dispersion by adding only 0.5 to 1 part by weight of the dispersant. .

It is preferable that metal oxide solid content in a dispersion solvent is 30 weight part or less. When the metal oxide solid content is more than 30 parts by weight, there is a problem in that the aggregation stability due to the collision between particles after dispersion is high and the storage stability is lowered.

In the metal oxide dispersion used in the present invention, the organic solvent for the dispersing solvent is preferably an alcohol which is easily evaporated during the baking process, and non-limiting examples include methyl alcohol, ethyl alcohol, n-propanol, isopropanol, butanol, hexanol, 2-isopropoxyethanol and the like.

In order to improve the appearance of the coating film by controlling the volatilization rate of the solvent when coating with the metal oxide dispersion, it is preferable to further use a polar organic solvent to the dispersion solvent. Non-limiting examples of polar organic solvents include acetonitrile, 2-aminoethanol, 4-butylacetone, N, N-dimethylformamide, dimethylsulfate, dimethylsulfoxide, 1,2-ethenediol, N-methylacetamide, N-methylpropionamide, N-nitrosodium methylamine, etc. are mentioned. 0-35 weight part is preferable with respect to 100 weight part of dispersion solvents, and 0-4 weight part is especially preferable. When the content of the polar organic solvent exceeds 35 parts by weight with respect to 100 parts by weight of the dispersion solvent, there is a problem of deteriorating appearance characteristics during coating or delaying drying.

In preparing the metal oxide dispersion, it is preferable to add the metal oxide to β-diketone and the organic solvent to disperse the same, or to disperse the same, and then carry out the grinding process. This is because as the surface area of the metal oxide particles is further increased, the amount of β-diketone bonded to the surface of the metal oxide is gradually increased. At this time, a device such as a paint shaker, a ball mill, a dynomill, a homogenizer or the like can be used for pulverizing the metal oxide powder.

At this time, when using equipment such as paint shaker or dynomill, it is necessary to adjust the size and content of the beads and the grinding time. Zirconia, silica and the like may be used as the material of the beads, the average particle diameter of the beads is preferably having a diameter of 0.2 to 2 mm. If the particle diameter of the beads is less than 0.2mm, there is a problem that uniform particle size adjustment is difficult, and if it exceeds 2mm, there is a problem that the milling time required for dispersion is long or dispersed.

The content of the metal oxide mixed in the dispersion during the grinding is preferably 30 to 60 parts by weight based on 100 parts by weight of the beads, and the grinding time is adjusted so that the secondary particle diameter of the metal oxide is 70 to 130 nm when the dispersion is ground using the grinder. There is a need. If the secondary particle diameter of the metal oxide exceeds 130 nm, there is a problem in that the whitening of the coating film is blurred, thereby deteriorating the appearance of the film, and in the case of less than 70 nm, the conductivity decreases.

The grinding time may vary depending on the content of the dispersant, the composition of the dispersion medium, the content of the metal oxides, etc., and most depends on the grinding equipment. Those skilled in the art will be able to readily determine the milling time by considering the conditions of the milling in detail.

For example, if a paint shaker is used, the metal oxide content is 10 to 20% by weight of the total dispersion, and zirconia beads having a diameter of 0.2 to 2 mm when a polar solvent and a dispersant in the above-described range are added. The grinding time is preferably 1 to 10 hours.

The conductive metal oxide dispersion prepared according to the present invention may form an electromagnetic shielding and antistatic conductive coating film when applied to a substrate. In addition, the electromagnetic shielding and antistatic conductive coating film includes an antireflective coating layer (second layer) and an antiglare coating layer (third layer) on a transparent conductive layer (first layer) formed by applying the conductive metal oxide dispersion of the present invention to a transparent substrate. Layer) may be further included.

For example, the transparent conductive layer forming dispersion prepared according to the method of the present invention is diluted with an organic solvent such as ethanol, and spin coated or spray coated on a transparent substrate such as a preheated CRT panel to form a transparent conductive layer (first layer). Manufacture. Next, an antireflective coating solution (second layer) containing an organic solvent such as a silicate (SiO ₂ ) binder and an alcohol is coated on top of the transparent conductive layer (eg, ITO film), and finally the same as the antireflective coating solution. The anti-glare coating liquid (third layer) composed of a silicate binder and an alcohol organic solvent may be spray coated to prepare an electromagnetic shielding and antistatic conductive coating film.

The metal oxide of the first layer forms a high refractive index coating layer, and the antireflective coating liquid of the second layer and the antiglare coating solution of the third layer form a low refractive index coating layer, and the visible light reflected from the first and second layers, respectively. The destructive interference of the lines lowers the reflectance of the entire coating layer. For this purpose, it is preferable that the thickness of each coating layer of the first layer and the second layer has a value of about 1/4 with respect to the wavelength? Of visible light.

On the other hand, the electrical conductivity of the antistatic coating film prepared according to the present invention increases with the firing temperature, it is preferable to perform the firing process at a temperature of about 200 ℃ or less to prevent breakage of the CRT panel. In addition, the firing process is performed after coating all three layers. When the surface resistance and reflectance of the antistatic coating film prepared and fired according to the present invention were measured, the surface resistance of 22 kΩ / □ or less and the reflectance of 1.5% or less were measured.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the examples are intended to illustrate the present invention, but are not intended to limit the following examples.

Example 1

12 g of tin indium tin oxide (ITO) powder was mixed with 59.6 g of ethanol, 6 g of 2-isopropoxyethanol, and 2.4 g of N, N-dimethylformamide, followed by addition of 0.08 g of acetylacetone. WDS analysis of the mixed ITO powder showed an element content of tin of 4.08 mol%, and X-ray diffraction analysis showed a BET surface area of 29.74 m ² / g with a primary particle diameter of 15.66 nm. The ITO powder is hereinafter referred to as A-type ITO powder.

The mixture of the A-type ITO powder, the dispersion solvent, and the dispersant was mixed with 185 g of 0.3 mm diameter zirconia beads, placed in a 125 ml polypropylene bottle, and ground for 2 hours using a paint shaker. The secondary particle size of the ground ITO dispersion was measured using a Dynamic Light Scattering (DLS), which was 124.3 nm.

The dispersion was diluted with ethanol such that the metal oxide solids content was 1.8% by weight and coated on a CRT panel preheated to 45 ± 3 ° C. at a speed of 140 rpm for 40 seconds. Next, the anti-reflective coating liquid mixed with 1.0% by weight of the silicate in isopropyl alcohol on the upper part of the ITO membrane was spin coated at a speed of 160 rpm for 45 seconds, and then preheated to 80 ° C. to prevent the anti-glare coating composed of 1.5% silicate and methanol. Was spray coated. Subsequently, baking was carried out at 180 ° C. for 30 minutes to prepare an ITO coating film.

The surface resistance of the transparent conductive coating film prepared by the above method was measured at the center and the outside of the CRT panel, respectively, and found to be 17 to 22 kΩ / □. In addition, the result of measuring the line resistance by soldering indium in the transverse direction of the CRT panel showed a value of 27.2 kΩ and showed a minimum reflectance of 0.64 ~ 0.73% in the wavelength range of 520 ~ 550 nm. In addition, the transparent conductive film had no whitening phenomenon and had a clean appearance without a comb pattern or the like on the surface of the coating layer.

Example 2

In Example 1, ITO powder instead of A-type ITO powder has an elemental content of 3.41 mol%, has a primary particle diameter of 22.02 nm, and has a BET surface area of 30.33 m ² / g (hereinafter referred to as B-type ITO). Except for using), an ITO coating solution and a transparent conductive coating film were prepared in the same manner as in Example 1.

As a result, the secondary particle diameter of the ITO dispersion was 128.5 nm, the surface resistance of the coating film was measured to 15 ~ 19 kΩ / □, the wire resistance was 23.5 kΩ. The optical properties of the coating film showed a minimum reflectance of 0.92 to 0.94% in the wavelength range of 520 ~ 560 nm. In addition, the transparent conductive film had no whitening phenomenon and had a clean appearance without a comb pattern or the like on the surface of the coating layer.

 Example 3

In Example 2, the dispersion of the metal oxide and the transparent conductive coating layer were prepared under the same conditions as in Example 2 except that the dispersion of the metal oxide was pulverized with the grinding time of the paint shaker being 8 hours.                     

As a result, the secondary particle diameter of the ITO dispersion was 91.3 nm, the surface resistance of the transparent conductive coating film was 22 ~ 28 kΩ / □, the wire resistance was measured as 30.4 kΩ. The optical properties of the coating film showed a minimum reflectance of 0.56 ~ 0.76% in the wavelength range of 530 ~ 570 nm. In addition, the transparent conductive film had no whitening phenomenon and had a clean appearance without streaks or the like on the surface of the coating layer.

 Example 4

In Example 2, a metal oxide was prepared under the same conditions as in Example 2, except that 0.8 g of acetylacetone was added to prepare a dispersion of the metal oxide after grinding the paint shaker for 8 hours.

As a result, the secondary particle diameter of the ITO dispersion was 89.5 nm, the surface resistance of the coating film was 22 ~ 25 kΩ / □, the wire resistance was measured as 28.5 kΩ. In addition, the transparent conductive film exhibited a minimum reflectance of 0.45 to 0.49% in the wavelength range of 530 to 570 nm, and the transparent conductive film had no whitening phenomenon and had a clean appearance without stripes on the surface of the coating layer.

 Example 5

In Example 2, a dispersion of the metal oxide and a transparent conductive coating film were prepared under the same conditions as in Example 2, except that 1.6 g of acetylacetone was added to prepare a dispersion of the metal oxide by grinding the paint shaker for 8 hours. It was.

As a result, the secondary particle diameter of the ITO dispersion was 91.4 nm, the surface resistance of the coating film was measured to 22 ~ 28 kΩ / □, the wire resistance was 30 kΩ. The optical properties of the coating film showed a minimum reflectance of 0.47 to 0.50% in the wavelength range of 500 to 560 nm, and the coating film had no whitening phenomenon and had a clean appearance.

 Example 6

In Example 2, a dispersion of the metal oxide and a transparent conductive coating film were prepared under the same conditions as in Example 2, except that 2.4 g of acetylacetone was added to prepare a dispersion of the metal oxide after grinding the paint shaker for 8 hours. It was.

As a result, the secondary particle diameter of the ITO dispersion was 91.3 nm, the surface resistance of the coating film was measured to 27 ~ 32 kΩ / □, the wire resistance was 31.4 kΩ. The optical properties of the coating film showed a minimum reflectance of 0.47 to 0.56% in the wavelength range of 500 to 560 nm.

Example 7

In Example 1, instead of A-type ITO powder, an ITO powder (hereinafter referred to as C-type ITO) having an elemental content of tin of 3.61 mol%, a primary particle diameter of 23.15 nm, and a BET surface area of 28.71 m ² / g was referred to. Except for the use, an ITO coating solution and a transparent conductive film were prepared in the same manner as in Example 1.

As a result, the secondary particle diameter of the ITO dispersion was 128.4 nm, the surface resistance of the coating film was measured to 14 ~ 17 kΩ / □, the wire resistance was 17.8 kΩ. The optical properties of the coating film showed a minimum reflectance of 1.56 ~ 1.76% in the wavelength range of 530 ~ 560 nm.

Example 8

In Example 1, instead of A-type ITO powder, an ITO powder having an elemental content of tin of 3.60 mol% and having a primary particle diameter of 22.14 nm and a BET surface area of 29.71 m ² / g (hereinafter referred to as D-type ITO) was used. Except that, an ITO coating solution and a transparent conductive film were prepared in the same manner as in Example 1.

As a result, the secondary particle diameter of the ITO dispersion was 116.5 nm, the surface resistance of the coating film was measured 19 ~ 21 kΩ / □, the wire resistance was 16.1 kΩ. The optical properties of the coating film showed a minimum reflectance of 0.72 ~ 0.83% in the wavelength range of 510 ~ 530 nm.

Example 9

In Example 2, a dispersion of metal oxides was prepared under the same conditions as in Example 2, except that 68 g of ethanol and 0.06 g of acetylacetone were used as the dispersion solvent, followed by grinding for 6 hours by a paint shaker.

As a result, the dispersion of ITO had a secondary particle diameter of 103.2 nm, and after 23 days, the secondary particle diameter was measured again, and showed excellent storage stability without showing particle reaggregation at 107.2 nm.

FIG. 1 shows the change of the secondary particle diameter according to the storage time of the dispersion in which acetyl acetone was used as the dispersant by changing only the ratio of dispersant to ITO solids in Example 9.

Example 10

In Example 2, a dispersion of metal oxides was prepared under the same conditions as in Example 2, except that 68 g of ethanol and 1.3 g of acetylacetone were used as the dispersion solvent, followed by 6 hours of grinding by a paint shaker.

As a result, the dispersion of ITO had a secondary particle diameter of 104 nm, and after 23 days, the secondary particle diameter was measured again, and showed excellent storage stability without showing particle reaggregation at 107 nm.

Example 11

In Example 1, 6 g of C-type ITO was mixed with 34 g of ethanol and then 0.04 g of dispersant 3-methyl-2,4-pentanedion was added. The mixture of the metal oxide, the dispersion medium, and the dispersant was mixed with 92.5 g of 0.3 mm diameter zirconia beads, placed in a 125 ml polystyrene bottle, and ground for 13 hours and 30 minutes using a paint shaker. As a result of measuring the secondary particle diameter of the dispersed ITO dispersion, it was confirmed that the dynamic light scattering apparatus is 126.3 nm. After 7 days after the preparation of the dispersion, the secondary particle size was again measured using DLS, and it was confirmed that it was 128.2 nm.

 Example 12

A dispersion of metal oxides was prepared under the same conditions as in Example 11, except that 0.12 g of 3-methyl-2,4-pentanedion was used for 10 hours and 30 minutes of grinding. The prepared ITO dispersion was confirmed by a dynamic light scattering device that the secondary particle diameter was 95.9 nm. As a result of re-measurement of the secondary particle diameter 7 days after the preparation of the dispersion, it was confirmed that it was 96.8 nm, and it could be seen that no serious aggregation phenomenon was performed.

 Comparative Example 1

As a dispersant, 0.06, 0.16, 0.3, 0.5, and 0.7 g of isopropyl tri (N-ethylenediamino) ethyl titanium coupling agent (Ken-React Co. KR44 ^TM ), a kind of titanium coupling agent, were added to disperse the metal oxide dispersion. A coating solution and a transparent conductive film were prepared under the same conditions as in Example 3 except for the preparation.

The surface resistance of the coating layer increased in proportion to the content of the dispersant used in the preparation of the dispersion, the values are listed in Table 1. In addition, it was observed that as the content of the dispersant increases, the appearance deterioration in which the stripe pattern is severely increased in the coating film is increased.

Comparative Example 2

A dispersion of metal oxides was prepared under the same conditions as in Example 9 except that 0.7 g of KR44, a kind of titanium coupling agent, was added as a dispersant. The secondary particle diameter of the ITO dispersion was 102.7 nm, but after 23 days, a significant aggregation phenomenon was observed in which the secondary particle diameter increased to 225.9 nm. Compared with the case of using acetylacetone, the storage stability of the coating solution was greatly reduced.

FIG. 2 illustrates the change of secondary particle diameters depending on the storage time of the dispersion liquid using KR44 as a dispersant by varying only the ratio of dispersant to ITO solid content in Comparative Example 2. FIG.

<Experiment>

A transparent conductive film utilizing the metal oxides of Examples 3, 4, 5, and 6, in which a dispersion of metal oxides was prepared by adding acetylacetone 0.08 g, 0.8 g, 1.6 g, and 2.4 g, respectively, as a dispersant. The surface resistance of the coating layer against is shown in Table 1.                     

Table 2 below shows the change in the surface resistance of the coating layer with increasing content of isopropyl tri (N-ethylenediamino) ethyl titanium coupling agent (KR44) in the dispersion of Comparative Example 1.

Since KR44 mostly exists on the surface of ITO particles after firing the coating layer, it acts as an insulating layer to increase the resistance of the coating layer. In contrast, acetylacetone is a solvent having a boiling point of 140 ° C., which is capable of completely evaporating at 180 ° C., which is the baking temperature of the coating film. Therefore, it can be assumed that there is almost no dispersant layer adsorbed on the surface of the secondary particles of ITO in the calcined coating film, and the electrical resistance generated by the adsorption layer can be ignored. Table 1 shows the surface resistance change of the coating layer with increasing content of acetylacetone in the dispersion. It can be seen that there is almost no change in surface resistance even if the content of acetylacetone is increased.

As described above, the metal oxide dispersion of the present invention exhibits improved dispersibility, exhibits surface resistance of less than 5 × 10 ⁴ Ω / □ and high light transmittance with a reflectance of less than 1% without deterioration of electrical conductivity. In addition, it is possible to provide an electromagnetic shielding and antistatic coating film having no whitening phenomenon and having a clean appearance.

Claims (14)

A metal oxide dispersion comprising a metal oxide and an organic solvent and characterized by using β-diketone as a dispersant, wherein the metal oxide solid content is 30 parts by weight or less, and the content of β-diketone is 100 weight of the metal oxide. Metal oxide dispersion, characterized in that 0.5 to 20 parts by weight relative to the part. The metal oxide dispersion according to claim 1, wherein the metal oxide is a conductive metal oxide, and the metal oxide dispersion is used as a coating liquid for an antistatic conductive layer of a front panel for a display device. The metal oxide dispersion according to claim 1, wherein the β-diketone has a lower boiling point than the firing temperature of the firing process performed after the metal oxide dispersion is applied to the substrate. A method of preparing the metal oxide dispersion according to claim 1, wherein the metal oxide is added to β-diketone and an organic solvent to be dispersed and simultaneously or dispersed. The method of claim 4, wherein the grinding process is performed using a bead having a diameter of 0.2 to 2 mm. The method of claim 1, wherein the β-diketone dispersant is 2,4-pentanedione (acetylacetone), 3-methyl-2,4-pentanedione, 3-isopropyl-2,4-pentanedione and 2,2 Metal oxide dispersion, characterized in that at least one selected from the group consisting of -dimethyl-3,5-hexanedione. The metal oxide dispersion according to claim 1, wherein the organic solvent is an alcohol. 8. The method of claim 7, wherein the organic solvent is acetonitrile, 2-aminoethanol, 4-butylacetone, N, N-dimethylformamide, dimethylsulfate, dimethylsulfoxide, 1,2-ethenediol, N-methylacetamide Metal oxide dispersion, characterized in that it further comprises at least one polar organic solvent selected from the group consisting of N-methyl propionamide and N-nitrosodium methylamine. delete The metal oxide dispersion according to claim 1, wherein the metal oxide has a particle diameter of 70 to 130 nm. The metal oxide dispersion according to claim 1, wherein the metal oxide is at least one selected from the group consisting of indium oxide, tin added indium oxide, tin oxide, antimony added tin oxide, aluminum added zinc oxide and titanium oxide. A front panel for a display device comprising a transparent substrate and a transparent conductive layer, wherein the transparent conductive layer is the metal of any one of claims 1 to 3, 6 to 8, 10 and 11. A front panel for a display device, formed by coating and firing an oxide dispersion on a transparent substrate. The front panel of claim 12, further comprising an anti-reflective coating layer and an anti-glare coating layer on the transparent conductive layer. The front panel of claim 12, wherein β-diketone dispersant is evaporated in the metal oxide dispersion during the firing process.

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