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Transparent conductive film and coating composition therefor

a technology of transparent conductive film and coating composition, which is applied in the direction of conductive layers on insulating supports, transportation and packaging, chemistry apparatus and processes, etc., can solve the problems of limited range of applicable substrate materials, difficult to uniformly disperse the fibers throughout the thermoplastic resin matrix, and difficulty in controlling electrical characteristics

Inactive Publication Date: 2006-11-23
MITSUI & CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0008] Therefore, this invention aims to provide a new transparent conductive film and a coating composition therefor capable of solving above mentioned problems in the arts. This invention also aims to provide a transparent conductive film and a coating composition therefor, which possesses improved and well controllable electrical properties by adding a small amount of additive or filler without damaging the characteristic of the matrix, while maintaining a good transparency of the film.
[0021] According to embodiments of the present invention, each of the carbon fibrous structures to be added to a matrix resin as an electrical conductivity imparting agent has a specific configuration in which some carbon fibers are bound to each other tightly by a granular part produced in a growth process for the carbon fibers wherein the concerned carbon fibers are outwardly elongated from the granular part. Such carbon fibrous structures can disperse easily into a matrix resin upon adding, while maintaining their sparse structure. Even when they are added at a small amount to the matrix, they can be distributed uniformly throughout the matrix. Therefore, with respect to electrical conductivity, it is possible to obtain good electrical conductive paths throughout the matrix even with a small dosage of added fibrous structures, thereby improving the electrical conductivity adequately and controllably of the conductive film. With respect to transparency of the film, a high degree of transparency can be maintained since the carbon fibrous structures can be uniformly distributed throughout the matrix.
[0022] Further, on preparing a coating composition for a transparent conductive film according to the present invention, using a media mill equipped with beads of a prescribed mean diameter, it is possible to achieve a good and uniform dispersion without adding any dispersion stabilizer such as a surfactant. In this way, breakdown of the carbon fibrous structures is avoided, and a transparent conductive film having good properties can be prepared with ease.
[0023] In addition, by subjecting the mixture of resinous composition and carbon fibrous structures to a dispersion treatment using a high-shear type distributor before dispersion treatment using a media mill, a more homogeneous distribution can be attained, which, in turn, leads to improve film properties on making the film film.

Problems solved by technology

However, there are several restrictions on these materials, such as difficulty in controlling their electrical characteristics, and limited range of applicable substrate materials.
In the transparent conductive resin boards shown in JP-2001-62952A, JP-2004-195993A and JP-2004-230690A, however, it is difficult to disperse the fibers uniformly throughout the thermoplastic resin matrix since the long carbon fibers or carbon nanotubes must be mixed in single-fiber form with the thermoplastic resin matrix.
Therefore, the resulting conductivity of the boards can hardly be expected to be uniformly inplane.
When kneading force is increased in order to enhance the dispersibility of the carbon fibers into the matrix, it occurs the problem that the fibers would be cut into shreds.
The increased amount of fibers will result in a reduction of transparency of the board.

Method used

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  • Transparent conductive film and coating composition therefor
  • Transparent conductive film and coating composition therefor
  • Transparent conductive film and coating composition therefor

Examples

Experimental program
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Effect test

synthetic example 1

[0086] Carbon fibrous structures were synthesized using toluene as a raw material in a CVD process.

[0087] The synthesis was carried out in the presence of a mixture of ferrocene and thiophene as a catalyst, and in the reducing atmosphere of hydrogen gas. The toluene and the catalyst were heated to 380° C. along with the hydrogen gas. The heated mixture was then supplied to a generation furnace and subjected to thermal decomposition at 1250° C. in order to obtain carbon fibrous structures (the first intermediate). The synthesized first intermediate was baked at 900° C. in nitrogen gas in order to remove hydrocarbons, such as tar, to produce a second intermediate. The R value of the second intermediate, as measured by Raman spectroscopic analysis, was found to be 0.98. A sample for electron microscopy was prepared by dispersing the first intermediate into toluene. FIG. 1 shows a TEM photo of the sample.

[0088] The second intermediate was further subjected to a high temperature heatin...

examples 1-9

[0091] The carbon fibrous structures obtained in Synthetic Example 1 was added to 100 parts by weight of polyurethane resin solution (non-volatile matter: 20%) at ratios shown in Table 1. The resultant mixture was pulverized and dispersed by using a bead mill (DYNO-MILL, manufactured by SHINMARU ENTERPRISES CORPORATION) with zirconium beads (0.05 mm, 0.5 mm, 1.0 mm, or 1.5 mm in diameter) at a peripheral speed of 10 m / sec, a bead filling rate of 80% by volume, and a processing time of 2 hrs. As a result, a coating composition comprising the carbon fibrous structures dispersed therein was prepared.

[0092] The liquid resinous composition obtained above was coated on a glass plate to obtain a hardened film of a prescribed thickness shown in Table 1. The hardened film was tested for coating ability, total light transmittance, and surface resistivity. The results obtained are shown in Table 1.

[0093] Furthermore, the dispersion condition of the carbon fibrous structures in the hardened c...

reference examples 1-6

[0094] To prepare the coating compositions of Reference Examples 1-6, the same procedure in Examples 1-9 was repeated except that the dispersion method and its condition were changed as shown in Table 1. Then, the same tests for coating ability, total light transmittance, and surface resistivity as in Examples 1-9 were performed. The results obtained are shown in Table 1.

Controls 1-4

[0095] Multilayered carbon nanotubes (manufactured by Tsinghua Nafine, 10-20 nm in outer diameter, several μm to several tens μm in length) were added to 100 parts by weight of a polyurethane resin solution (non-volatile matter: 20%) at ratios shown in Table 1. The resultant mixture was pulverized and dispersed by using a bead mill (DYNO-MILL, manufactured by SHINMARU ENTERPRISES CORPORATION) with zirconium beads (0.05 mm, or 1.5 mm in diameter) at a peripheral speed of 10 m / sec, a bead filling rate of 80% by volume, and a processing time of 2 hrs. As a result, a coating composition comprising the carb...

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Abstract

The disclosed is a transparent conductive film that includes a matrix and carbon fibrous structures added to the matrix, wherein the carbon fibrous structures comprise carbon fibers, each having an outside diameter of 15-100 nm, and wherein the carbon fibrous structures each comprise a granular part at which two or more carbon fibers are bound to each other, and wherein the granular part is concurrently produced in a growth process for the carbon fibers. When the transparent conductive film is formed at a thickness of 0.1-5 μm on a glass substrate, it shows a surface resistivity of not more than 1.0×1012Ω / □, and a total light transmittance of not less than 30%. A coating composition for the conductive transparent film is prepared by using a media mill equipped with beads having an average diameter of 0.05-1.5 mm to disperse the carbon fibrous structures into the liquid resinous composition.

Description

CROSS REFERNCE TO RELATED APPLICATIONS [0001] This claims priority of Japanese Patent Application No. 2005-132691, filed on Apr. 28, 2005, the disclosure of which, including the specification, claims, drawings and summary, is incorporated herein by reference in its entirety. BACKGROUND OF THE INVENTION [0002] 1. Technical Field [0003] This invention relates to a transparent conductive film and a coating composition for the transparent conductive film. More particularly, this invention relates to a transparent conductive film that has a good transparency and a high conductivity, as well as to a coating composition for forming the transparent conductive film. Background Art [0004] Transparent conductive films have been utilized as electrode materials for liquid crystal display devices, organic electroluminescent (EL) devices, and various other electronic devices. They have also been used for the purpose of removing static electricity from transparent members in order to prevent sticki...

Claims

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Application Information

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IPC IPC(8): D04H1/00
CPCB82Y30/00B82Y40/00C01B31/0253C01B2202/06H01B1/24C01B2202/36C08J5/042C08K7/06C01B2202/34C01B32/168Y10T428/249924H01B5/14
Inventor HANDA, KOICHISUBIANTORO,TSUKADA, TAKAYUKISHAN, JIAYIASHIDA, TADASHINATORI, TOSHIKI
Owner MITSUI & CO LTD
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