Process for producing noble-metal type fine-particle dispersion, coating liquid for forming transparent conductive layer, transparent conductive layered structure and display device

a technology of fine particles and coating liquids, applied in the direction of electrically conductive paints, colloidal chemistry, conductors, etc., can solve the problems of low picture quality, difficult to achieve good conductivity as the transparent conductive layer, and insufficient shielding of leaking electric fields. achieve the effect of low cos

Inactive Publication Date: 2005-09-29
SUMITOMO METAL MINING CO LTD
View PDF2 Cites 10 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

This process enables the production of transparent conductive layers with superior conductivity, high transmittance, and low reflectance, while maintaining storage stability and reducing production costs, suitable for various display devices.

Problems solved by technology

Hence, this has not been adequate for shielding the leaking electric fields.
In practice, however, oxide films are necessarily formed on the surfaces of such fine metal particles in the atmosphere, and hence it is difficult to attain good conductivity as the transparent conductive layer.
This method, however, can not be said to be preferable so much because its employment may bring about a low resolution, resulting in a low picture quality.
This causes in-plane non-uniformity of brightness when conventional color glass (e.g., semi-tinted glass; transmittance: about 53%) is used in panel glass.
However, there has also been a problem that the addition of fine color-pigment particles or the like tends to make the transparent conductive layer have a little low conductivity.
On the other hand, there may be other problem that filters tend to clog at the time of filtering treatment of the transparent conductive layer forming coating liquid, or that coating film defects may occur if the agglomeration of fine metal particles has proceeded in excess.
Now, in the above methods (a) to (d), the methods (a) and (d) are not practical because they are methods in which the dispersion stability of fine metal particles is made to lower (the zeta potential of the system lowers and the stability lowers) to form the agglomerates and hence, if left as it is, the agglomeration may gradually proceed as the fine metal particles are kept unstable.
However, this step is so complicate that these methods have not been preferable methods.
However, such a transparent conductive layer forming coating liquid of the kind that originally the agglomerates are formed by heating at tens of degree of temperature can not be said to ensure high dispersion stability of the fine metal particles themselves contained therein.
Hence, there has been a problem that the agglomerates formed have also a low dispersion stability.
If on the other hand the fine metal particles themselves have a high dispersion stability, it takes a long time to form the agglomerates by heating at tens of degree of temperature.
Thus, this method can not still be said to be practical.
Hence, there is a problem that the agglomerates further agglomerate one another and settle in, e.g., a concentrating step taken thereafter for preparing the transparent conductive layer forming coating liquid, and further it is necessary to determine the state of agglomeration of fine metal particles in advance.
Thus, this method has been inconvenient in that the state of agglomeration of the fine metal particles can not be changed at will in the subsequent stage.
In addition, the method (e) is a method in which mechanical dispersion treatment is carried out to form the agglomerates of fine metal particles, and hence it has had a problem that it requires an expensive treatment equipment and also the step of treatment can not be said to be simple.

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0106] A colloidal dispersion of fine silver particles was made up by the Carey-Lea process described previously.

[0107] Stated specifically, to 330 g of an aqueous 9% silver nitrate solution, a mixed solution of 390 g of an aqueous 23% iron (II) sulfate solution and 480 g of an aqueous 37.5% sodium citrate solution was added, and thereafter the sediment formed was filtered and washed, followed by addition of pure water to make up a colloidal dispersion of fine silver particles (Ag: 0.15%).

[0108] To 600 g of this colloidal dispersion of fine silver particles, 80.0 g of an aqueous 1% solution of hydrazine monohydrate (N2H4.H2O) was added, and a mixed solution of 4,800 g of an aqueous potassium aurate KAu(OH)4 solution (Au: 0.075%) and 2.0 g of an aqueous 1% polymeric dispersant solution was further added with stirring to obtain a colloidal dispersion of noble-metal-coated fine silver particles coated with gold alone.

[0109] This colloidal dispersion of noble-metal-coated fine silver...

example 2

[0121] 5 g of fine titanium nitride (TiN) particles (available from Netsuren Co., Ltd.) and 5 g of the silica sol (liquid D) prepared in Example 1 were mixed with 20 g of pure water and 70 g of ethanol, and these were subjected to paint shaker dispersion together with zirconia beads, followed by desalting with the ion exchange resin used in Example 1, to obtain a dispersion of silicon-oxide-coated fine titanium nitride particles of 85 nm in dispersed-particle diameter (liquid E), surface coated with silicon oxide.

[0122] Next, to the noble-metal type fine-particle dispersion according to Example 1 (liquid C), the above liquid E, acetone, ethanol (EA), propylene glycol monomethyl ether (PGM), diacetone alcohol (DAA) and formamide (FA) were added to obtain a transparent conductive layer forming coating liquid according to Example 2 (Ag: 0.04%; Au: 0.16%; TiN: 0.15%; water: 3.1%; acetone: 40%; EA: 36.5%; PGM: 15%; DAA: 5%; FA: 0.03%, containing the chainlike agglomerates of noble-metal...

example 3

[0142] A dispersion containing noble-metal-coated fine silver particles standing monodisperse in a high concentration (Ag—Au: 1.6%; water: 20.0%; EA: 78.4%) (liquid F) was obtained in the same manner as the manner of obtaining the liquid B in Example 1.

[0143] Next, stirring 60 g of this liquid F, 0.8 g of a hydrazine solution (N2H4.H2O: 0.5%) (0.8 g corresponding to 67 ppm of hydrazine, based on the 1.6% Ag—Au dispersion) was added thereto over a period of 1 minute. Thereafter, this was retained at room temperature for 15 minutes, followed by further addition of 0.6 g of a hydrogen peroxide solution (H2O2: 1.0%) over a period of 1 minute to obtain a noble-metal type fine-particle dispersion according to Example 3 (liquid G), in which chainlike agglomerates of the noble-metal-coated fine silver particles stood disperse in a high concentration.

[0144] To this liquid G, ethanol (EA), propylene glycol monomethyl ether (PGM), diacetone alcohol (DAA) and formamide (FA) were added to obta...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

PropertyMeasurementUnit
particle diameteraaaaaaaaaa
particle diameteraaaaaaaaaa
temperatureaaaaaaaaaa
Login to View More

Abstract

A process for producing a noble-metal type fine-particle dispersions, having the steps of an agglomeration step of add ing a hydrazine solution to a dispersion in which primary particles of noble-metal type fine particles have been made to stand monodisperse in a solvent, to destabilize the dispersibility of the noble-metal type fine particles in the dispersion and cause the plurality of primary particles in the noble-metal type fine particles to agglomerate in the form of chains to obtain a dispersion of chainlike agglomerates; and a stabilization step of adding a hydrogen peroxide solution to the dispersion of the chainlike agglomerates obtained, to decompose and remove the hydrazine to stabilize the dispersibility of the chainlike agglomerates in the dispersion.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] This invention relates to a process for producing a noble-metal type fine-particle dispersion (liquid dispersion) in which noble-metal type fine particles have been dispersed in a solvent. More particularly, it relates to improvements in a process for producing a noble-metal type fine-particle dispersion in which the noble-metal type fine particles make up chainlike agglomerates, and also in a coating liquid for forming transparent conductive layers (hereinafter “transparent conductive layer forming coating liquid”) which is obtained by this process, a transparent conductive layered structure which is obtained by using the transparent conductive layer forming coating liquid, and a display device incorporated with such a transparent conductive layered structure. [0003] 2. Description of the Related Art [0004] At present, in cathode ray tubes (CRTs; also called Braun tubes) used as computer displays and so forth, it i...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
Patent Type & AuthorityApplications(United States)
IPC IPC(8): C09C1/36B01J13/00B22F1/0545B22F1/148B22F9/24C09C1/48C09C1/62C09C3/06C09D1/00C09D5/00C09D5/24H01B1/00H01B1/22H01B13/00
CPCB01J13/0043B22F1/0022B22F1/0096B22F2998/00B82Y30/00Y10T428/12889Y10T428/1086Y10T428/24917Y10T428/2991Y10T428/25H01B1/22C09K2323/06B22F1/0545B22F1/148
InventorYUKINOBU, MASAYASUEKANE, YUKIKO
OwnerSUMITOMO METAL MINING CO LTD