JP2000304914A - Color filter and liquid crystal display element using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid crystal cell using an electrically conductive polymer color filter almost free from increase in consumption of electric power by using an electrically conductive polymer free from ionic components and provided on an electrode as a material for developing colors of the color filter. SOLUTION: As the material for developing colors of the color filter, not an ionic component but an organic acceptor is used as a component capable of constituting a combined body with an electrically conductive polymer. Electrically conductive polymers are used without specific restriction, and polymers of heterocyclic compounds, fused polycyclic compounds, amine compounds or the like are used as the electrically conductive polymer. Concretely, a polypyrrole, a polythiophene or the like is cited as an example. An organic acceptor molecule to be used is at least one of the whole non-ionic molecules which are capable of allowing the electrically conductive polymer to change color at the time of contacting with the electrically conductive polymer being in a dedoped state and are taken in the electrically conductive polymer. Concretely, 2,3-dichloro-5,6-dicyano-p-benzoquinone(DDQ) or the like is cited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color filter and a liquid crystal display device using the color filter.

[0002]

2. Description of the Related Art In recent years, there has been remarkable progress in downsizing, thinning, and lightening of electronic devices. Particularly in the OA field, the size and weight of electronic devices have been reduced from desktop types to laptop types and notebook types. In addition, the field of new small electronic devices such as electronic notebooks and translators has emerged. In addition to the multifunctional and miniaturized conventional telephones of the stationary type, small communication devices such as mobile phones, PHS, PDA development is also underway. Such electronic devices have become smaller and thinner,
In the wave of weight reduction, display devices supporting man interfaces have been required to have higher performance. In response to such demands, a display device using a liquid crystal (LCD) is thin, light, and capable of being colored, so that it is rapidly becoming a display device suitable for small and medium-sized electronic devices replacing CRTs. The development has been advanced. Liquid crystal display devices have come to be used in various fields.
It is the momentum of RT.

[0003] Such display colorization (single color, multicolor,
There is a color filter as a technology that supports (full color). Conventionally, when manufacturing color filters, a method of casting a dye solution (dispersion), a method of applying a photosensitive material in which a dye is dispersed in a photoresist to a substrate by screen printing or the like, performing a mask exposure, A silver salt method in which a material is dispersed and exposed, and an electrodeposition method in which a dye is electrodeposited on a substrate electrode are known. However, in this method, it is difficult to apply a dye to a predetermined position, and in the method, there is a problem that alignment with an electrode is difficult.

In particular, in recent years, the density of pixels of a liquid crystal display device has been increased to 100,000 pixels or more, and the pixel size tends to be as fine as about 20 μm square. For this reason, alignment accuracy of ± 1 μm or less is required, and it is becoming more difficult to produce a color filter. In particular, when a plastic substrate is used, a large dimensional change occurs unlike a glass substrate. As a matter of course, the thermal history causes a dimensional change of as much as 0.1% depending on the temperature and humidity at which the film is placed, so that it is very difficult to perform precise alignment. In view of such circumstances, the present inventors have proposed a color filter using a conductive polymer that does not require alignment in Japanese Patent Application No. 10-210472.

However, in the above-mentioned invention, since the ionic dopant is used for expressing the color of the conductive polymer, the ionic dopant diffuses into the liquid crystal, resulting in an increase in current consumption and a deterioration in display quality. I was

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a color filter using a conductive polymer as a material for expressing the color of a color filter.

[0007]

Means for Solving the Problems The present inventor has conducted various studies to solve the above problems, and as a result, unlike the preceding invention, a composite with a conductive polymer was used as a material for expressing the color of a color filter. The present invention solves the above-described problems by using a complex with an organic acceptor instead of an ionic component as a component that can be constituted, and has found that a conductive polymer is used as a material that expresses the color of a color filter. Could be reached.

An attempt to use a conductive polymer as a material for a color filter has already been made in JP-A-8-76106 and JP-A-7-110474.
In -76106, the conductive polymer is not used as a material for expressing the color of the color filter, but is treated as mere conductive particles, and a dye or a pigment is separately used as a coloring material. For this reason, the configuration is fundamentally different from the configuration of the present invention. Further, the invention discloses that polypyrrole, polythiophene, or the like is used as a specific example of the conductive polymer as the conductive material. However, usually, the conductive polymer is colored in a conductive state (polypyrrole, polythiophene, etc.). No blue), and there is no disclosure of the relationship with the separately used colorant gradient. In addition, Japanese Patent Application Laid-Open
Similarly, 110474 does not use a conductive polymer as a material for expressing the color of a color filter, but uses a conductive base material for forming a color filter, and uses a separate phosphor as a coloring material. In addition, it discloses that polyacetylene, polyaniline, or the like is used as a specific example of the conductive polymer as the conductive base material, but does not consider the coloring state of the conductive polymer at all.

The conductive polymer used in the present invention is not particularly limited, and examples thereof include polymers such as heterocyclic compounds, condensed polycyclic compounds, and amine compounds. More specifically, polypyrrole, polythiophene, poly 3-methylthiophene,
Examples include polyphenylene, polyazulene, polyaniline, polydiphenylbenzidine, isothionaphthene, and derivatives thereof. The conductive polymer used is not particularly limited, but is selected according to a desired color. Specifically, polypyrrole is red, reddish brown, cyan, blue (depending on the state of the polymer), polythiophene, poly-3-methylthiophene is red, cyan, blue, and polyaniline is yellow, cyan, blue, green, magenta (polymer ), The polyisothianaphthene becomes green. By appropriately using such a conductive polymer, a single-color display, a multi-color display, a full-color display using three primary colors of additive color mixture (red, blue, green) or three primary colors of subtractive color mixture (yellow, cyan, magenta) are provided. It is possible to do. Among such conductive polymers, polyaniline is preferably used. Polyaniline has excellent stability and can be changed into a plurality of colors depending on processing conditions, even though it is a single material. In particular, the three primary colors of subtractive color mixing or the two primary colors of additive color mixing can all be represented by one kind of polyaniline. In the case of multicolor display, it is not necessary to use a plurality of conductive polymer manufacturing apparatuses. It is possible to increase productivity in terms of cost, operation, and material cost.

The conductive polymer used in the present invention can be formed by an electrolytic polymerization method. The electrolytic polymerization method is generally described, for example, in Chemical Industry, June 1986, p. As shown in the February issue (1986), page 124, a solution obtained by dissolving a monomer and an electrolyte in a solvent is placed in a predetermined electrolytic cell, and the electrode is immersed. It can be carried out by causing a polymerization reaction.

As a method other than electrolytic polymerization, chemical polymerization can be used. Since chemical polymerization is carried out by bringing an oxidizing agent into contact with a monomer, it is generally synthesized as a powder. Therefore, in order to form a film, the conductive polymer to be synthesized is soluble or fusible in a solvent. In the case of, it can be prepared by painting. In the case of insolubility or infusibility, a film can be formed by applying or impregnating the substrate with an oxidizing agent and bringing the substrate into contact with a monomer solution or a monomer gas. Conversely, it is also possible to apply and impregnate the monomer on the substrate side. As a synthesis method, it is preferable to use electrolytic polymerization.

The organic acceptor molecule used in the present invention is a nonionic molecule that causes a color change in the conductive polymer upon contact with the undoped conductive polymer and is incorporated into the conductive polymer. It refers to everything, and there is no particular limitation on its use, but it should be selected according to the color to be developed. In general, a conductive polymer represented by polyaniline or polypyrrole has a low ionization potential and a strong donor property, and is considered to spontaneously form a complex with an organic acceptor molecule. In addition, the complex of the conductive polymer and the organic acceptor molecule in the present invention can be considered as an intermolecular charge transfer complex, but the oxidation-reduction potential of the conductive polymer and the oxidation of the organic acceptor, which prove the charge transfer, can be considered. Energy absorption due to charge transfer based on the difference in reduction potential (charge transfer band appearing in the visible and near-infrared spectrum) has not been confirmed at present. For this reason, it is not known by what mechanism the conductive polymer and the organic acceptor form the complex according to the present invention, but the organic acceptor molecule in the present invention is the same as the undoped conductive polymer. It is defined in terms of nonionic molecules that cause the conductive polymer to change color upon contact and are incorporated into the conductive polymer.

Specific examples of the organic acceptor molecules include, for example, 2,3-dichloro-5,6-dicyanoparabenzoquinone (DDQ), tetracyanoparabenzoquinone (TCNQ), 2,6-dichloroparabenzoquinone (DCBQ), Tetracyanoethylene (TCNE), naphthoquinone (NQ), parabenzoquinone (BQ), 2,
3,5,6-tetrachloroparabenzoquinone (chloranil), 2,3,5,6-tetrabromoparabenzoquinone (bromanyl), 2-methylparaparabenzoquinone (M
BQ), anthraquinone (AQ), 2,3,5,6-tetramethylparabenzoquinone (TMBQ), oxygen and the like.

In the method of combining a conductive polymer and an organic acceptor molecule, first, the conductive polymer immediately after synthesis by both electrolytic polymerization and chemical polymerization generally contains an ionic dopant. A process for removing the ionic dopant is required. In the case of an electrolytic polymer, after applying a reduction potential in a suitable electrolyte and sufficiently undoping,
It can be obtained by contacting with a base such as ammonia gas or aqueous ammonia or a reducing agent such as hydrazine and washing with pure water. In addition, as a method that can be carried out irrespective of an electrolytic polymer or a chemical polymer, it can also be obtained by directly contacting a conductive polymer immediately after polymerization with a base or a reducing agent, followed by washing. When the ionization energy of the obtained undoped conductive polymer is small, it is often unstable in the air, and therefore, it is preferably performed in an inert atmosphere (anoxic).

[0015] The conductive polymer thus obtained is
As a method of bringing the organic acceptor molecule into contact with the organic acceptor molecule, when the organic acceptor molecule is in a gaseous state, the organic acceptor molecule may be brought into contact with the organic acceptor molecule. You may make it contact as it is. In the case of a solid, a preferred method is to dissolve it in an appropriate solvent and contact it. As a method for synthesizing the conductive polymer described above, it is preferable to use electrolytic polymerization that does not require alignment when a plurality of colors are formed on the same substrate. Hereinafter, the electrolytic polymerization will be described in detail.

As the monomer, the above-mentioned monomer for providing a conductive polymer is used. Specific examples include pyrrole, thiophene, 3-methylthiophene, benzene, azulene, aniline, diphenylbenzidine, isothionaphthene, and derivatives thereof.

The electrolyte may be, for example, an anion.
BF₄ ⁻, AsF₆ ⁻, SbF₆ ⁻, PF₆ ⁻, Cl
O₄ ⁻, HSO₄ ⁻, SO₄ ^2-, Aromatic sulfonic acids,
Cl ⁻, Br⁻, I⁻And the like,
As the cation, H⁺Quaternary ammonium cation,
Alkali metal clicks such as lithium, sodium, and potassium
ON can be exemplified, but is not limited to these.
No.

Examples of the solvent include water, acetonitrile, benzonitrile, propylene carbonate, γ-
Examples include butyrolactone, dichloromethane, dioxane, dimethylformamide, and nitro solvents such as nitromethane, nitropropane, and nitrobenzene. Further, it can be used as a mixed solvent of two or more kinds, but is not particularly limited thereto.

The electrolytic polymerization can be carried out using any of constant voltage electrolysis, constant current electrolysis, and constant potential electrolysis. However, constant current electrolysis and constant potential electrolysis are preferable. preferable. In brief, the generation process by the reaction of the conductive polymer is such that radical cation species generated by the extraction of electrons from the monomer on the reaction electrode (or in the reaction medium) (in the case of oxidation) are dimerized, Molecules are synthesized by growing molecules by trimerization. In addition, at this time, oxidation of the product oligomer and polymer also occurs in a concerted manner. If an electrolyte component is present in the polymerization solution, in the case of an oxidation reaction, the anion species (dopant) is incorporated into the polymer and the polymer is converted into a conductive polymer. The formation takes place. The monomer used in the present invention and a polymer synthesized by a reaction using an electrolyte solution (reaction solution) may be used as is (as-grown) for the purpose of the present invention even immediately after preparation (as-grown). Can not. It is necessary to perform the dedoping treatment as described above.

When the color filter of the present invention employs electrolytic polymerization, alignment with the liquid crystal driving electrode does not need to be performed as described above. Therefore, the color filter is preferably used for a liquid crystal display element using a plastic substrate which is inherently highly elastic. Can be used. At least one of the plastic film substrates used in the present invention is preferably a material having a light transmitting property, and is preferably transparent to visible light due to the characteristics of the display element. General-purpose polymer materials can be used, but materials with low retardation, low gas permeability (moisture, oxygen, nitrogen), high transmittance of visible light, low linear expansion coefficient, and high heat resistance preferable.

When a polarizing plate is used in the present invention,
The polarizing plate (polarizer) is not particularly limited, such as a reflection type, a scattering type, a refraction type, a birefringence type, a single crystal dichroism type, a polymer dichroism type, but a flexible one is preferable. Polymeric dichroic polarizers are most preferably used.

Similarly, when a retardation plate is used, the type of the retardation plate is not particularly limited. However, it is preferable that the retardation plate has flexibility. (Moisture, oxygen, nitrogen), a material having high transparency of visible light, a small coefficient of linear expansion, and high heat resistance are preferable. Similarly, when a reflecting plate is used, the reflecting plate is not particularly limited, but a flexible film is preferably used because a flexible film is preferably used. It is preferable to use aluminum because it can be easily formed into a thin film and is inexpensive. More preferably, a configuration in which the driving electrode also functions as the reflection plate is preferable since double embossment and color shift are unlikely to occur.

[0023]

EXAMPLE 1 Polyethersulfone sheet (P) having ITO on the surface
ES: Sumitomo Bakelite, 150 micron thick) cut out to 8.5cm x 5.5cm, and 8.5c at the center
Two substrates (an upper substrate and a lower substrate) were prepared by etching and removing the edge portions while leaving ITO of mx 4.5 cm. 2.75M separately containing 0.5M aniline
Prepared in aqueous _H 2 SO _4, and cooled to 0 ° C.. Immediately after immersing one of the ITO substrates in this aqueous solution, 0.8Vv
Aniline was electropolymerized at a constant potential of sSCE (saturated calomel electrode).

The polymerized polyaniline on ITO had a green color. This ITO polyaniline complex was added to 0.1.
For a saturated calomel electrode in a 1M aqueous sulfuric acid solution, -0.4
After applying a potential of V and performing de-dove, the resultant was immersed in a 10% hydrazine hydrate / methanol solution for 5 minutes, and vacuum-dried at 80 ° C to obtain a reduced polyaniline.

At this time, the polyaniline had a white color.
Separately, acetonitrile subjected to vacuum freezing and degassing was mixed with 0.1 M 2,6-dichloroparabenzoquinone (D
A solution in which CBQ) was dissolved was prepared. The above-mentioned polyaniline was immersed and left in this solution at room temperature for 72 hours under an oxygen-free atmosphere in an argon atmosphere. The polyaniline organic acceptor complex was sufficiently washed with acetonitrile subjected to vacuum freeze degassing to obtain a magenta filter. Further, an overcoat of resin was applied on the polyaniline, and dried at 130 ° C. to flatten the surface.

An alignment film forming solution was applied by spin coating to the magenta filter and an ITO substrate without a filter, and dried at 120 ° C. to form an alignment film. Next, the two alignment films were subjected to a rubbing treatment by a rubbing machine so that the twist angle after producing the liquid crystal cell was 240 degrees, and the substrate was washed with ultrapure water and dried. A spacer spray liquid in which a silica spacer (center particle size: 5.2 μm) was dispersed in alcohol was prepared, and a spinner was sprayed on a substrate containing only ITO by a spin coater and dried at 80 ° C. for 1 minute.

Next, a sealant for bonding the upper substrate and the lower substrate is printed and formed on the filter substrate side by screen printing, and the upper substrate and the lower substrate are striped from each other by ITO.
Were bonded so as to be orthogonal. The sealant was cured by heating. FIG. 1 shows a cell before liquid crystal injection.
Next, the cell was transferred to a liquid crystal injection vacuum device,
After the pressure was reduced to rr, the liquid crystal injection port of the cell was attached to the liquid crystal grain, the outside of the cell was returned to normal pressure, and the liquid crystal was introduced into the cell.
The cell was taken out of the vacuum device and the inlet was sealed. An upper retardation plate and a lower retardation plate were adhered to this with an adhesive. Further, the upper polarizing plate (using a polymer dichroic deflector) and the lower polarizing plate (using a polymer dichroic deflector) were fixed with an adhesive. When an AC voltage of 64 Hz and 4.5 V was applied to the manufactured liquid crystal cell, it was confirmed that the liquid crystal was normally driven. FIG. 2 shows the absorption spectrum of the polyaniline film. It can be seen from the spectrum that the display is magenta. After the liquid crystal cell was stored at 85 ° C. for 1000 hours, the current consumption was measured and found to be 2.4 μA / cm ² .

Comparative Example Polyethersulfone sheet having ITO on the surface (P
ES: Sumitomo Bakelite, 150 micron thick) cut out to 8.5cm x 5.5cm, and 8.5c at the center
Two substrates (an upper substrate and a lower substrate) were prepared by etching away the end portions while leaving ITO of mx 4.5 cm. 2.75M separately containing 0.5M aniline
Prepared of _H 2 S0 ₄ aqueous solution was cooled to 0 ° C.. One of the ITO substrates is immersed in this aqueous solution and immediately immersed in 0.8Vv
Electropolymerization of aniline was performed at a constant potential of sSCE (saturated calomel electrode). The polymerized polyaniline on the ITO exhibited a border color. This ITO polyaniline complex was sufficiently washed with ion-exchanged water to obtain a green filter.
Further, an overcoat of resin was applied on the polyaniline, and dried at 130 ° C. to flatten the surface. The alignment film forming solution was applied by spin coating to the green filter and the ITO substrate without a filter, and dried at 120 ° C. to form an alignment film.

Next, a liquid crystal cell is manufactured by a rubbing machine.
Two alignment films are applied so that the subsequent twist angle is 240 degrees.
After rubbing, the substrate is washed with ultrapure water and dried.
Was. Silica sparger (center particle size 5.2mm) in alcohol
Prepare a sprayer liquid in which Glon is dispersed, and use ITO
Spray the spinner on the substrate only with a spin coater,
Dried at 80 ° C. for 1 minute. Next, screen printing
Fill the sealant to adhere the upper and lower substrates.
The upper substrate and the lower substrate are printed
Laminated ITO was attached so that they intersected at right angles. heating
This cured the sealant. Before the liquid crystal injection
FIG. Next, the cell is transferred to a vacuum device for liquid crystal injection.
After reducing the pressure to 0.002 Torr,
The liquid crystal inlet and return the outside of the cell to normal pressure.
Introduced into the cell. Remove the cell from the vacuum device and fill the inlet
Was sealed. The upper retarder and the lower retarder are then
Pasted. Furthermore, an upper polarizer (using a polymer dichroic deflector)
) And lower polarizer (using polymer dichroic deflector) with adhesive
Fixed. 64 Hz and 4.5 V were applied to the prepared liquid crystal cell.
That the liquid crystal is operating normally
Was confirmed. This liquid crystal cell is operated at 85 degrees for 1000 hours.
After storage, the current consumption was measured to be 4.4 μA / cm
²Met.

Example 2 A polyaniline color filter was prepared in the same manner as in Example 1 except that parabenzoquinone (BQ) was used as the organic acceptor. FIG. 3 shows the absorption spectrum of the polyaniline film. It can be seen from the spectrum that cyan is displayed.

Example 3 A polyaniline color filter was prepared in the same manner as in Example 1 except that tetracyano parabenzoquinone (TCNQ) was used as the organic acceptor. FIG. 4 shows the absorption spectrum of the polyaniline film. It can be seen from the spectrum that the display is yellow.

Example 4 A. G. FIG. Mac. Diarmd. et. al. , Con
ducting Polymer, 105 (1987)
Polyaniline was synthesized by chemical polymerization using ammonium persulfate as an oxidizing agent according to the method described in (1). After sufficiently washing the synthesized polyaniline with a 1N aqueous hydrochloric acid solution,
After stirring overnight in a hydrazine aqueous solution containing water, the product was sufficiently washed with an aqueous solution containing hydrazine containing water and dried at 100 ° C. in vacuo to obtain reduced polyaniline. Separately, a solution prepared by dissolving 0.1 M benzoquinone (BQ) in acetonitrile subjected to vacuum freeze degassing was prepared. The above-mentioned polyaniline was immersed and left in this solution at room temperature for 72 hours under an oxygen-free atmosphere in an argon atmosphere. The polyaniline organic acceptor complex was sufficiently washed with acetonitrile subjected to vacuum freeze degassing. This powdery polyaniline was subjected to elemental analysis, and it was confirmed that 2.9% of BQ was contained.

Example 5 A polyaniline organic acceptor composite was prepared in the same manner as in Example 4 except that 2,3-dichloro-5,6-dicyanoparabenzoquinone (DDQ) was used. Elemental analysis confirmed that 14.3% of DDQ was included.

[0034]

[Effect] 1. Claims 1 and 2 It is possible to provide a liquid crystal cell using a conductive polymer color filter in which current consumption hardly increases. 2. Around 3 When a conductive polymer color filter can be selectively formed on a substrate electrode. 3. (4) A colored layer of three primary colors of subtractive color mixture or two primary colors of additive color mixture can be represented by one kind of polyaniline on a substrate. 4. Claim 5 It is possible to provide a liquid crystal display device which can display three primary colors of an additive warm color with a small increase in current consumption and can efficiently form a color filter.

[Brief description of the drawings]

FIG. 1 is a diagram showing a liquid crystal cell before liquid crystal injection in Example 1.

FIG. 2 is a view showing an absorption spectrum of a magenta polyaniline film of the liquid crystal cell of Example 1.

FIG. 3 is a diagram showing an absorption spectrum of a yellow polyaniline film of a liquid crystal cell of Example 4.

FIG. 4 is a diagram showing an absorption spectrum of a cyan polyaniline film of a liquid crystal cell of Example 5.

[Explanation of symbols]

 Reference Signs List 1 ITO electrode 2 Lower substrate 3 Upper substrate 4 Liquid crystal injection port 5 Sealant part

Continued on the front page F term (reference) 2H048 BA01 BA43 BA47 BB42 2H091 FA03Y FB02 FC06 FC24 FC29 FC30 FD04 FD12 FD24 GA06 HA10 LA11 LA13 LA15 LA30 4J002 CE001 CM011 CM051 EE056 ET006 GP00

Claims (5)

[Claims] 1. A color filter, wherein the material that expresses the color of the color filter is a conductive polymer formed on an electrode and containing no ionic component. 2. The color filter according to claim 1, wherein the conductive polymer is a complex with an organic acceptor. 3. The color filter according to claim 1, wherein the conductive polymer is formed by an electrolytic reaction. 4. The color filter according to claim 1, wherein the conductive polymer is polyaniline. 5. A liquid crystal display device using the color filter according to claim 1.