KR101538075B1 - Conductive composition forming ground electrodes of liquid crystal display - Google Patents

Abstract

The present invention relates to a conductive composition for forming a back electrode of a liquid crystal display, and more particularly, to a conductive composition comprising a) 0.1 to 10 parts by weight of a conductive polymer; b) 0.1 to 10 parts by weight of a dopant; c) 3 to 30 parts by weight of a silane coupling agent; And d) 50 to 90 parts by weight of a solvent to optimize the degree of dispersion of the conductive polymer in the composition, thereby providing an antistatic back electrode having excellent transparency and surface hardness in a liquid crystal display device. ≪ / RTI >

Conductive Polymer, Backside Electrode, Liquid Crystal Display, Transmittance, Surface Hardness

Description

[0001] The present invention relates to a conductive composition for forming a back electrode of a liquid crystal display device,

The present invention relates to a conductive composition for forming a back electrode of a liquid crystal display device, and more particularly, to a conductive composition for forming a back electrode of a liquid crystal display device capable of providing an antistatic back electrode having excellent transmittance and surface hardness in a liquid crystal display .

BACKGROUND ART In a liquid crystal display device, a back electrode serves to block static electricity applied from the outside.

In the case of ITO (Indium Tin Oxide) or IZO (Indium Zincoxide) used as a back electrode (Korean Registered Patent No. 0603826) in a conventional liquid crystal display, a vacuum deposition process is required, and its resistance and surface hardness are excellent in its characteristics, There are disadvantages.

In addition, development of various transparent electrode materials for replacing ITO has recently become a serious issue due to the exhaustion of indium resources. However, many transparent electrode materials under development, such as conductive polymers or inorganic conductive compositions such as metals and metal oxides It is still unsatisfactory in terms of transmittance.

In order to solve the problems of the prior art as described above, the present invention provides a conductive composition for forming a back electrode of a liquid crystal display device and a back electrode of a liquid crystal display using the conductive composition for improving the transmittance and surface hardness of the back electrode of a liquid crystal display And a method of forming the same.

In order to achieve the above object,

a) 0.1 to 10 parts by weight of a conductive polymer;

b) 0.1 to 10 parts by weight of a dopant;

c) 3 to 30 parts by weight of a silane coupling agent; And

d) 50 to 90 parts by weight of a solvent;

And a conductive layer formed on the conductive layer.

The present invention also provides a method of forming a back electrode of a liquid crystal display device, wherein the conductive composition for forming the back electrode is coated on a substrate.

The conductive composition for forming the back electrode of the present invention optimizes the dispersion degree of the conductive polymer in the composition to improve the transmittance and surface hardness of the back electrode in a liquid crystal display device (LCD), in particular, a transverse electric field liquid crystal display device such as IPS or FFS Can be remarkably improved.

Hereinafter, the present invention will be described in detail.

Hereinafter, the back electrode described in the present invention includes not only the back electrode of a liquid crystal display device but also a coating film of a conductive polarizer (Korean Patent Registration No. 0592329) which can replace the conventional back electrode.

The conductive composition for forming a back electrode of a liquid crystal display of the present invention comprises a) 0.1 to 10 parts by weight of a conductive polymer; b) 0.1 to 10 parts by weight of a dopant; c) 3 to 30 parts by weight of a silane coupling agent; And d) 50 to 90 parts by weight of solvent.

The conductive polymer used in the present invention is a basic substance that makes the composition of the present invention conductive.

The conductive polymer may include polyaniline, polypyrrole, polythiophene and derivatives thereof, and polymers polymerized with monomers (aniline, pyrrole, thiophene) as monomers. Examples of the polymer polymerized with the monomer of the derivative of the monomer include poly (3,4-ethylenedioxythiophene) polymerized with 3,4-ethylenedioxythiophene, which is a derivative of thiophene.

Particularly, the conductive polymer is preferably poly (3,4-ethylenedioxythiophene) (PEDOT, poly (3,4-ethylenedioxythiophene)).

The conductive polymer is contained in an amount of 0.1 to 10 parts by weight based on the composition of the present invention. When the content of the conductive polymer is less than 0.1 parts by weight, the resistance is drastically increased. When the content of the conductive polymer is more than 10 parts by weight, the permeability is decreased and the dispersion characteristics and stability of the composition are hardly maintained.

Also, the dopant used in the present invention is at least one compound selected from the group consisting of dodecylbenzenesulfonic acid, toluenesulfonic acid, camphorsulfonic acid, benzenesulfonic acid, hydrochloric acid, styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid and their salt compounds. Sulfosuccinic acid ester salt, sodium 5-sulfoisophthalic acid, dimethyl-5-sodium sulfoisophthalate, 5-sodium sulfo-bis (? -Hydroxyethylisophthalate, etc. Preferably, Poly (4-styrene sulfonate) (PSS).

The dopant is preferably included in the composition of the present invention in an amount of 0.1 to 10 parts by weight. If the content is out of the above range, the resistance becomes high and the dispersion characteristic becomes weak.

The silane coupling agent used in the present invention has an effect of improving the dispersibility of the conductive polymer in the composition.

The silane coupling agent may be an alkyloxysilane type, an amino silane type, a vinyl silane type, an epoxy silane type, a methacryloxy silane type, an isocyanate silane type, a fluorine silane type, or the like. More specifically, examples of the silane coupling agent include TEOS (tetraethyloxysilane), vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris (? -Methoxyethoxy) silane,? -Methacryloxypropyltrimethoxy Silane,? - (3,4-epoxycyclohexyl) ethyltrimethoxysilane,? -Glycidoxypropyltrimethoxysilane,? -Mercaptopropyltrimethoxysilane,? -Aminopropyltriethoxysilane, N -amino propyl triethoxysilane,? - (aminoethyl) -? - aminopropyltrimethoxysilane,? - ethylidene propyltriethoxysilane, phenyltriethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, polyethylene oxide denatured silane monomer , Polymethylethoxysiloxane, hexamethyldisilazane, and the like.

The silane coupling agent is preferably contained in an amount of 3 to 30 parts by weight, more preferably 5 to 15 parts by weight, based on the composition of the present invention. When the content is less than 3 parts by weight, surface staining due to phase separation tends to appear when the coating layer is formed, and surface hardness may be lowered. When the content is more than 30 parts by weight, resistance increases and stability of the composition deteriorates.

The solvent used in the present invention is an alcohol, a diol and a polyol such as methyl alcohol, ethyl alcohol, isopropanol, ethylene glycol, butanediol, neopentyl glycol, 1,3-pentanediol, 1,4-cyclohexanedimethanol, Diols or polyols selected from the group consisting of monomers comprising ethylene glycol, polyethylene glycol, polybutylene glycol, dimethylol propane and trimethylol propane or derivatives thereof; Halogen such as chloroform, dichloromethane, tetrachlorethylene, trichlorethylene, dibromoethane and dibromopropane; Normal methyl pyrrolidone, dimethyl sulfoxide; Triethylamine, tributylamine, trioctylamine; Cresol and the like may be used.

The solvent is preferably contained in an amount of 50 to 90 parts by weight with respect to the composition of the present invention. When the content is less than 50 parts by weight, the stability of the composition is deteriorated. When the content is more than 90 parts by weight, not only the resistance is high, but it is also vulnerable to impact.

The conductive composition of the present invention comprising the above components may further contain a binder resin as required.

The binder resin may be a polyacrylic resin, a polyurethane resin, an epoxy resin, a polyester resin, etc. The content of the binder resin may be 0.1-30 parts by weight per 100 parts by weight of the composition.

The present invention also provides a method of forming a back electrode of a liquid crystal display device, wherein the conductive composition for forming the back electrode is coated on a substrate.

In the method of forming a back electrode of the liquid crystal display device, a conventional coating method may be used. For example, a conventional coating method such as a spraying method, a bar coating method, a doctor blade method, a roll coating method, Method can be applied.

The coating is preferably coated on the substrate in a thickness of 0.5-1 탆. After that, soft coating is performed on a hot plate at about 80 캜 to form a 300-500 nm thick film layer And dried in an oven at about 120 DEG C to form a rear electrode of the liquid crystal display device.

The conductive composition for forming the back electrode of the liquid crystal display of the present invention can improve the transmittance of the back electrode by optimizing the dispersion degree of the conductive polymer in the composition. Also, if the conductive composition of the present invention can be coated so as to have no defects on the adhesion surface with the substrate, the transmittance thereof can be remarkably improved. In addition, the back electrode coated with the conductive composition of the present invention has excellent surface hardness.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the scope of the present invention is not limited to the following examples.

[Example]

Example 1

2 parts by weight of PEDOT-PSS, 4 parts by weight of TEOS (tetraethyloxysilane), 50 parts by weight of IPA (isopropyl alcohol), 20 parts by weight of ethylene glycol, 0.1 part by weight of surfactant and 1 part by weight of hydrochloric acid or acetic acid diluted solution Thereby preparing a conductive composition for forming a back electrode of a liquid crystal display device.

The composition was applied on the electrode formed on the substrate to a thickness of 0.5 탆 and then soft baked on a hot plate at 80 캜 for 180 seconds to form a film layer having a thickness of 300 nm and dried in an oven at 120 캜 for about 1 hour.

Example 2

The procedure of Example 1 was repeated except that tetraethyloxysilane was used in an amount of 8 parts by weight in the conductive composition of Example 1.

Example 3

The procedure of Example 1 was repeated except that 12 parts by weight of tetraethyloxysilane was used in the conductive composition of Example 1. [

Comparative Example 1

The procedure of Example 1 was repeated except that tetraethyloxysilane was not used in the conductive composition of Example 1.

Comparative Example 2

A glass substrate on which ITO (Indium Tin oxide) was vacuum-deposited to a thickness of 50 nm was used.

Comparative Example 3

IZO (Indium Zincoxide) was vacuum deposited on the glass substrate to a thickness of 50 nm.

The coating uniformity, surface resistance, permeability and hardness were measured using the substrates of Examples 1 to 3 and Comparative Examples 1 to 3, and the results are shown in Table 1 below.

The surface resistivity was evaluated using a Loresta (4-point probe) manufactured by Mitsubishi Chemical Co., Ltd. The surface resistance per unit area was evaluated by measuring the transmittance at 550 nm using a UV-visible spectrophotometer, The film hardness was measured using a pencil hardness tester, and the coating uniformity was excellent (⊚: roughness less than 2% based on the coating thickness), excellent (∘: roughness of 2-5% Roughness greater than 5% over coating thickness).

[Table 1]

division Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Coating uniformity ○ ◎ ◎ ○ ○ ○ Surface resistance (Ω / sq) 110K 36K 40K 43K 100K 120K Transmittance (400 nm) 97% 100% 99% 94% 89% 87% Hardness (1kgf) 4H 9H 9H 3H 9H 7H

As shown in Table 1, the substrates of Examples 1 to 3 according to the present invention showed excellent results over coating uniformity, surface resistance, transmittance and pencil hardness as compared with Comparative Examples 1 to 3. In particular, Examples 2 and 3 exhibited excellent coating properties, and all other items showed excellent surface resistance, transmittance, and pencil hardness. In particular, in Examples 1 to 3 of the present invention, the effect of the present invention was more than 95%, and even in Example 2, it was 100%. This is because the coating layer compensates the roughness of the glass substrate Reflection and scattering are reduced.

Claims (9)

a) 0.1 to 10 parts by weight of a conductive polymer, poly (3,4-ethylenedioxythiophene) (PEDOT, poly (3,4-ethylenedioxythiophene)); b) 0.1 to 10 parts by weight of a dopant poly (4-styrene sulfonate) (PSS, poly (4-styrene sulfonate)); c) 5 to 15 parts by weight of TEOS (tetraethyloxysilane); And d) 50 to 90 parts by weight of a solvent; And a conductive layer formed on the back electrode layer. delete delete delete delete delete The method according to claim 1, The solvent may be selected from the group consisting of methyl alcohol, ethyl alcohol, isopropanol, ethylene glycol, butanediol, neopentyl glycol, 1,3-pentanediol, 1,4-cyclohexanedimethanol, diethylene glycol, polyethylene glycol, polybutylene glycol, A solvent prepared by an esterification reaction of at least one alcohol, diol or polyol selected from the group consisting of monomers comprising propane and trimethylol propane or derivatives thereof; At least one halogen selected from the group consisting of chloroform, dichloromethane, tetrachlorethylene, trichlorethylene, dibromoethane and dibromopropane; Normal methyl pyrrolidone, dimethyl sulfoxide; Triethylamine, tributylamine, trioctylamine; And cresol. 2. The conductive composition for forming a back electrode of a liquid crystal display device according to claim 1, The method according to claim 1, Wherein the composition further comprises 0.1 to 30 parts by weight of a binder resin which is at least one selected from the group consisting of a polyacrylic resin, a polyurethane resin, an epoxy resin and a polyester resin. Conductive composition. A method for forming a back electrode of a liquid crystal display device, comprising: coating a substrate with a conductive composition for forming a back electrode according to claim 1;