JP3460762B2 - Carbon black for insulating black matrix - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to carbon black for an insulating black matrix, and more specifically, carbon for an insulating black matrix used for optical color filters used in, for example, color televisions, liquid crystal color televisions, cameras and the like. Regarding black.

[0002]

2. Description of the Related Art In a liquid crystal display device, a transparent substrate such as glass provided with a transparent electrode is provided at intervals of about 1 to 10 μm and a liquid crystal substance is enclosed between them, and the liquid crystal is kept constant by a voltage applied between the electrodes. The image is displayed by orienting in the direction to form a transparent portion and an opaque portion. The color liquid crystal display device is provided with a color filter of three colors of red (R), green (G), and blue (B) corresponding to the three primary colors of light on one of the transparent electrode substrates, and the color filters are applied to the transparent electrodes. By adjusting the voltage, the transmission of light from the liquid crystal is controlled to control the amount of light transmitted through the filters of three colors R, G, and B, and color display is performed by coloring by adding the three primary colors.

The R, G, B colored layers are formed on a substrate on which a black matrix film for partitioning the respective colors is provided in advance, a method of forming a black matrix film after forming R, G, B, etc. Although there are various types, the role of the black matrix is to partition the three primary colors of R, G, and B, and to shield the liquid crystal driving electrode or the transistor such as TFT (thin film transistor) provided on the substrate facing the color filter. Has the effect of The black matrix of the color filter used for such a purpose can be roughly classified into two types.

(1) Black matrix made of a metal film such as Cr processed by photolithography method: high resolution and high light-shielding ratio, and an optical density (OD) of 3.0 or more can be easily obtained near a film thickness of 0.1 μm. However, since the reflectance of visible light is as high as about 40% due to the metal film, the contrast of the display image is reduced due to the reflection of external light, and a bright object in the surrounding is reflected on the black matrix surface and overlaps with the display image. It is easy to cause reflections and reduce image quality. In addition, since the Cr film sputtering and photolithography processes are long, it is difficult to reduce the cost.

(2) Obtained by patterning an organic resin film in which a black pigment is dispersed by a photolithography method, a printing method, or a photoetching method, or by patterning a photosensitive resin film and then dyeing it with a black dye. A black matrix made of a black organic resin film, and because it is black, the reflectance of visible light is as low as a few percent or less, and the contrast of the displayed image is reduced due to the reflection of external light, and the reflection of bright objects in the surrounding area is a metal film black matrix. Compared with, the image quality is improved significantly. However, there is a drawback that the light blocking rate is low. That is, in the photolithography method, when the light blocking rate is increased, the amount of exposure light reaching the interface with the substrate decreases, so that the high light blocking rate is set (for example, optical density 3.
At 0, the amount of transmitted light reaching the substrate is 1/1000), and the pattern peeling of the organic resin film occurs during development, and the black matrix cannot be formed. If the exposure amount is increased in order to avoid this, the pattern size becomes thick, and it becomes difficult to realize a predetermined resolution. Further, the printing method and the photo-etching method are slightly less restrictive than the photolithography method, but since the content of the black coloring material is limited, a high light-shielding rate results in a large film thickness during printing (for example, a film thickness of 1 ．
When the optical density is 0 μm and the optical density is 2.0, the film thickness becomes 3.3 μm when the optical density is increased to 3.0.) The resolution, which is essentially inferior to that of the photolithography method, is further reduced, and There is a possibility that the black matrix cannot be formed.

Generally, a black matrix made of a black organic resin film has a film thickness of 1 to 2 μm at an optical density of 2.0 to 2.5 as compared with a black matrix made of a metal film.
However, if the film thickness exceeds 1.5 μm, the surface flatness of the substrate completed by forming a color filter, protective film and transparent electrode on it will exceed 0.5 μm. If the liquid crystal display panel is used as a liquid crystal display panel, color unevenness, white spots, brightness unevenness, etc. occur, and the display image quality deteriorates. Therefore, the thickness of the black matrix is 1 μm
It is extremely important that the thickness is preferably 0.5 μm or less.

On the other hand, regarding the transparent protective film and the transparent pixel electrode, for example, in JP-A-4-130401, a conductive light-shielding pattern layer, a transparent insulating layer, a color filter pattern layer, a transparent protective film layer, and An electrode-attached color filter in which a transparent conductive pattern layer is sequentially formed is described. Here, the transparent protective film and the transparent insulating layer improve the surface smoothness of the transparent electrode and the solvent resistance of the color filter, and further, the conductive light-shielding layer (black matrix) and the transparent conductive layer ( It is formed for the purpose of electrical insulation from the transparent electrode).

However, recently, the transparent protective film and the transparent insulating film are removed for the purpose of cost reduction and further thinning of the color filter (liquid crystal display device), and smoothness and insulation usable for the color filter and the black matrix itself are obtained. There is active research to give them sexuality. Furthermore, the drying temperature after applying the black matrix or RGB resist is set to 22.
There is also a demand for increasing the temperature to 0 ° C or higher, preferably 250 ° C or higher. That is, there is a strong demand for a black matrix that maintains the insulating property even after the resist-coated surface is treated at a high temperature. However, especially with regard to insulating properties, since conductive materials are used for both the metal film such as chromium and chromium oxide as the main component of the black matrix and the carbon powder such as carbon black and graphite, the insulating property under the low temperature heat treatment condition is used. Is extremely difficult, and new materials have been desired.

[0009]

Based on this point of view, the present invention provides a black matrix comprising a black light-shielding film, which cannot be realized by the conventional method and which has a high light-shielding ratio with a thin film and a low surface reflectance. An object of the present invention is to provide a carbon black suitable for a color filter having, and at the same time, to provide a carbon black for an insulating black matrix that can be used even under high-temperature processing conditions having a function of a transparent protective film or a transparent insulating film at low cost. To do.

[0010]

The present invention has a total oxygen content of 1
5 mg / g or more and total oxygen content / specific surface area of 0.10 or less
The gist is carbon black for an insulating black matrix, which is obtained by coating the above carbon black with a polyfunctional epoxy resin.

The present invention will be described in detail below.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, carbon black click of coating a resin in the present invention include carbon black such as the following is used. (I) the amount of the total oxygen is 15 mg / g or more and the total amount of oxygen / the specific surface area is Ru der 0.10 or more. The surface of carbon black particles has hydroxyl groups (-OH) and carbonyl groups.

[0012]

[Chemical 1]

There is an oxygen functional group such as a carboxyl group (-COOH) group, and the amount of the oxygen functional group significantly changes the resistance when compounded in a resin or the like. Usually, the oxygen functional group is measured by the volatile composition, and the amount of hydroxyl group or carbonyl group can be quantified as CO or the amount of carboxyl group as CO ₂ . The total oxygen amount is an amount converted from CO and CO ₂ , and it is necessary that the total oxygen amount is 15 mg / g or more, preferably 20 mg / g or more. Further, it is necessary that the value of the oxygen amount per unit surface area divided by the specific surface area is 0.10. It is preferably 0.15 or more.

The above volatile component composition is 10 ^-2 mmHg when a certain amount of dried carbon black is put in a heat-resistant sample tube.
After reducing the pressure to 0, mount it in an electric furnace heated to 950 ° C,
Volatiles were desorbed for 30 minutes. After collecting and mixing the whole amount in a tank, the composition and amount of the gas are measured by gas chromatography to calculate the CO ₂ / CO ratio (weight ratio) and the total oxygen amount / specific surface area.

The specific surface area is measured by the BET method. That is, the nitrogen adsorption amount of carbon black was measured by the low-temperature nitrogen adsorption method using a low-temperature nitrogen adsorption device "Sorptomatic 1800" (Italya, manufactured by Carlo Erba Co., Ltd.), and was calculated by the multipoint method using the BET formula. It is a thing.

(Ii) Carbon black having an ash content of 1.0% by weight or less and a DBP absorption amount of 140 ml / 100 g or less is preferable. The composition of the ash is an alkali metal such as Na, K, or Ca, an alkaline earth metal, or the like, and if carbon black containing these is blended with a resin or the like, the insulating property decreases. It is considered that this is because the ionic conductive substance such as Na, K, and Ca has a high water absorbing property, so that the absorptivity of the carbon black-resin composite is increased and, as a result, the insulating property is lowered.

The reduction of the ionic conductive substance can be achieved by examining the raw material oil during the production of carbon black, the examination of the spray water used during the rapid cooling, the examination of the additives and the like. It can also be achieved by washing the carbon black produced from the production furnace with water or pickling. Further, it can be achieved by combining the examination of raw materials, spray water, additives and the like at the time of production with washing with water, pickling and the like. The content of the ionic conductive material present in the carbon black is represented by the amount of ash remaining when the carbon black is calcined in air at 750 ° C. for 4 to 6 hours,
The ash content of the carbon black of the composition of the present invention must be 1.0% by weight or less. 0.5% by weight or less is preferable.

When the DBP absorption measured by JIS-K6221-A exceeds 140 ml / 100 g, the blackness of the carbon black itself is lowered, and a sufficient sense of density is obtained when it is blended with a resin varnish for black matrix and applied. Not only that, but also the viscosity of the paste becomes high, and a coating film with good smoothness may not be obtained. The DBP absorption amount needs to be 140 ml / 100 g or less. It is preferably 120 ml / 100 g or less.

In the present invention, a polyfunctional epoxy resin is used as the resin to be coated. Specific resins include glycidylamine type epoxy resin triphenylglycidylmethane type epoxy resin tetraphenylglycidylmethane type epoxy resin aminophenol type epoxy resin diamidediphenylmethane type epoxy resin phenol novolac type epoxy resin orthocresol type epoxy resin bisphenol A novolac type epoxy resin Resins and the like can be used, and as a representative example of these products, regarding "Sumiepoxy" ELM manufactured by Sumitomo Chemical Co., Ltd.
-434, ELM-120, ELM-100 and the like.
For example, taking the products of Yuka Shell Epoxy Co., Ltd. as an example: "Epicoat" 1032H60, "Epicoat" 1
032H50: "Epicoat" 1031: "Epicoat" 154, "Epicoat" 630: "Epicoat" 604: "Epicoat" 152: "Epicoat" 180S65: "Epicoat" 157S65, "Epicoat" 15
7S70 etc.

These polyfunctional epoxy resins are used together with a curing agent and a curing accelerator according to a conventional method. In the present invention, of course, other than these polyfunctional epoxy resins, other resins can be appropriately used in combination.
The coating amount of the resin with respect to the carbon black is preferably 5 to 40 wt% with respect to the total amount of the carbon black and the resin, and if the amount is less than 5 wt%, only the same dispersibility and dispersion stability as the untreated carbon black can be obtained. There is a risk. On the other hand, when it exceeds 40 wt%, the adhesiveness between the resins is strong, and the resin becomes a mass in the shape of a dumpling, which may prevent the dispersion from progressing.

The carbon black thus coated with a resin can be used as a light-shielding material for an insulating black matrix according to a conventional method, and a color filter having this insulating black matrix as a constituent element can be processed according to a conventional method. Can be created. For example, in preparing a black matrix resist composition of the present invention, first, a coating solvent, a dispersant, and carbon black are added.
0.5 hours to 3 with a bead mill using glass beads or zirconia beads having a diameter of 0.1 to several mm, a paint shaker or a valve homogenizer, and a three-roll mill.
By dispersing for 0 hours, the carbon black concentration is 10
A 70% by weight dispersion is obtained. Next, a photopolymerization initiator composition, an ethylenic compound (adhesion improver for developed image), an organic polymer (adhesion improver with substrate), etc. are added to this dispersion and mixed to disperse the resist composition. Prepare things.

The optimum blending ratio for preparing the black matrix resist composition is as follows. The dispersant is 1 to 100% by weight with respect to carbon black, and the photopolymerization initiator composition is 0.2 to 100% with respect to the black matrix resist composition excluding carbon black.
30 wt%, preferably 0.2 to 20 wt% The ethylenic compound is 50 to 95 with respect to the resist composition for black matrix excluding carbon black.
% By weight, preferably 60 to 90% by weight Organic polymer is 10 to 70% by weight, preferably 20 to 60% by weight, based on the resist composition for black matrix excluding carbon black. Carbon black is contained in the resist composition. 35 to 80% by weight, preferably 50 to 70% by weight, based on the total solid content of the solvent. The solvent is 50 to 95% by weight, preferably 70 to 90% by weight, based on the entire photopolymerizable composition of the above.
It is adjusted to be in the range of weight%.

As the above-mentioned substances other than the carbon black used here, all substances generally used for the same purpose can be used, but the following substances are particularly preferable examples. "Dispersant" A polymeric dispersant such as a urethane-based, acrylic-based, or polyimide-based thermosetting resin, or an acrylic-based, vinyl chloride-based, or polyamide-based thermoplastic resin is preferable. "Photopolymerization initiator composition" Dicyclopentadienyl-Ti
-Bis-2,3,5,6-tetrafluorophenyl-1
-Yl and dicyclopentadienyl-Ti-bis-2,
A composite of a titanocene compound of 3,4,5,6-pentafluorophenyl-1-yl and a sensitizing dye having absorption at a wavelength of 400 to 500 nm is preferable.

"Ethylene compound" Ethylenic unsaturation obtained by an addition reaction between an aromatic polyglycidyl ether compound and an unsaturated monocarboxylic acid or an addition reaction between an aromatic polyhydroxy compound and an epoxy monocarboxylic acid ester. An ethylenic compound having two or more double bonds (hereinafter referred to as "ethylenic compound (A)") is preferable, and together with the ethylenic compound (A), an aliphatic polyhydroxy compound and an unsaturated carboxylic acid. It is preferable to use together an ethylenic compound containing two or more ethylenically unsaturated double bonds (hereinafter referred to as “ethylenic compound (B)”) obtained by an addition reaction (ester reaction) with.
Specific examples thereof include dipentaerythritol hexaacrylate as the co-condensation monomer (B) of bisphenol A and epichlorohydrid as (A).

"Organic polymer substance" Styrene, α-methylstyrene, benzyl (meth) acrylate, hydroxyphenyl (meth) acrylic acid, methoxyphenyl (meth) acrylic acid, hydroxyphenyl (meth) acrylamide, hydroxyphenyl (meth) The copolymerizable monomer having a phenyl group such as acrylsulfoamide is added to 10 to 8
0 mol%, preferably 20 to 70 mol%, more preferably 30 to 60 mol%, and other (meth) acrylic acid 2 to 50 wt%, preferably 5 to 40 wt%, more preferably Copolymers contained in a proportion of 5 to 30% by weight, or 2 to 50 mol%, preferably 5 to 40 mol%, more preferably 10 based on all copolymerized monomers.
Reactants with ~ 30 mol% epoxy (meth) acrylate added are preferred.

"Solvent" Methyl cellosolve, ethyl cellosolve, butyl cellosolve, ethyl cellosolve acetate, diethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate (hereinafter abbreviated as "PGMEA"), methyl ethyl ketone,
Examples thereof include methyl isobutyl ketone, cyclohexanone, toluene, chloroform, dichloromethine, ethyl acetate, methyl lactate, ethyl lactate, methanol, ethanol, propanol, butanol, and tetrahydrofuran. By using the carbon black of the present invention, an insulating black matrix having a high light-shielding rate, a low surface reflectance and a small film thickness can be achieved at low cost. It is presumed that the dispersibility and dispersion stability of carbon black were significantly improved with respect to the resin and solvent constituting the insulating black matrix liquid (with conventional carbon black, no matter how kneaded, it is 0.1 μm or less. It is difficult to disperse up to, and even if dispersed, the stability is poor and the agglomeration increases with time.)

V. E. According to Ghoul et al. (1970, "Research and application of conductive polymers"), the transfer of electric charge required for electricity flow is caused by the surface of chains composed of particles of filler and particles utilizing thermal radiation heat. It is considered to be carried out mainly in the interior, and depending on the conditions such as applied voltage and temperature, the electron jump over the potential barrier (potential barrier) is performed by the so-called tunnel effect. According to the present invention, preferably, carbon black having many surface functional groups is used, and the surface is further covered with a highly insulating resin, so that ionic substances such as Ca and Na are confined and contact between conductors is insulated. It is presumed that high insulation was achieved due to the fact that the coating film made it impossible for electrons to jump. In addition, the reason why the degree of decrease in resistance is small even when treated at high temperature and the insulating property can be maintained is that the coating resin is a polyfunctional type, so that the wettability with carbon black is improved and the microstructure of carbon black particles is improved. It is considered that even this portion is uniformly coated and that the resin itself has excellent heat resistance.

[0028]

The present invention will be described in more detail with reference to the following examples. [Example-1] Carbon black was produced by an ordinary oil furnace method. However, as the raw material oil, Na, C
Ethylene bottom oil with a small amount of a and S was used, and coke oven gas was used for combustion. Further, as the reaction stopped water, pure water treated with an ion exchange resin was used for production.

[0029] This carbon black, inner diameter 10cm carbon black 50 g, placed in a cylindrical kiln length 15cm, 2 hours while rotating the mixed gas of air and ozone (ozone 6000 ppm) at 9 rpm, treated by contacting did. Carbon black click product properties are shown in Table 1.

540 g of the obtained carbon black A was mixed with 14500 g of pure water using a homomixer to obtain 6,000.
The mixture was stirred at rpm for 30 minutes to obtain a slurry. Epoxy resin "Epicoat 630" 60g while transferring this slurry to a container with a screw type agitator and mixing at about 1,000 rpm
600 g of dissolved toluene was added little by little. In about 15 minutes, the entire amount of carbon black dispersed in water was transferred to the toluene side to form particles of about 1 mm.

Next, after draining with a 60-mesh wire net, it was placed in a vacuum dryer and dried at 70 ° C. for 7 hours to completely remove toluene and water. The amount of residual toluene in the obtained carbon black was 50 ppm, and the amount of water was 500 ppm. A resist composition for a black matrix was prepared from this carbon black by the following method. 1 mm
In a sand mill containing 300 g of zirconia beads with a diameter of
32 g of carbon black and organic polymer substance 1 having the following structure
8 g and propylene glycol monomethyl ether acetate (hereinafter abbreviated as PGMEA) 15 as a solvent
0 g was added and mixed and dispersed at 2000 rpm for 10 hours to obtain a dispersion liquid.

[0032]

[Chemical 2]

Next, the black matrix resist composition was prepared by adding 1 g of zirconia beads having a diameter of 1 mm.
45 g of the above dispersion liquid in 40 cc of mayonnaise, 1.13 g of dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd.) as an ethylenic compound, and a cocondensation monomer of bisphenol A and epichlorohydrin (manufactured by Showa High Polymer Co., Ltd. SP-1509 ") 1.13 g, and further 0.37 g of ethyl P-diethylaminobenzoate as a photopolymerization initiator composition and 39 g of PGMEA were added, and dispersed by a paint conditioner for 30 minutes to prepare. (Hereinafter, this dispersion is referred to as a paste.) The obtained composition is a glass substrate that has been subjected to high-pressure water washing, ultraviolet irradiation and ozone treatment (Corning No. 705).
9. The thickness of the resist composition for a black matrix is applied onto the above composition by spin coating to form 220
Heat treatment was performed at 3 levels of temperature between ℃ and 260 ℃ to form a resist layer having a film thickness of 1.0 µm.

The physical properties of the carbon black used here and the evaluation results of the obtained coating film are as shown in Table-1 and Table-2. The OD (optical density) values in the table were measured using a Macbeth reflection densitometer "RD-914" (sold by Sakata Inx Co., Ltd.). The surface resistance of the coating film surface was measured with a high resistance measuring instrument “HIRESTA MCP-HT21” manufactured by Yuka Denshi Co., Ltd.
It was measured using "0".

[Examples 2 and 3] The coating amount of the epoxy resin on the carbon black was 5 w.
Same as Example 1 except that t% and 15 wt%. [Comparative Example 1] The same as Example 1 except that carbon black A not coated with an epoxy resin was used. [Comparative Example 2] The same as Example 1 except that "Epicoat 830 " in Example 1 was used instead of "Epicoat 630".

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

According to the carbon black of the present invention, a black matrix having a high light-shielding rate, a low surface reflectance and a small film thickness can be achieved at a low cost, and a transparent protective film or a transparent insulating film is unnecessary. A black matrix that can withstand high temperatures can be achieved.

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Claims (4)

(57) [Claims] 1. A total oxygen content of 15 mg / g or more and a total acid content.
A carbon black for an insulating black matrix, which is obtained by coating a carbon black having an elementary amount / specific surface area of 0.10 or more with a polyfunctional epoxy resin. 2. The carbon black for a black matrix according to claim 1, wherein the coating amount of the resin is 5 to 40 wt% with respect to the total amount of the carbon black and the resin. 3. The carbon black for a black matrix according to claim 1, wherein the resin coating is carried out by adding a resin liquid dissolved in a solvent in a state where a dispersion liquid of water and carbon black is stirred. 4. A color filter having an insulative black matrix, wherein the black filter uses a carbon black coated with a polyfunctional epoxy resin as a light shielding material.