JPH10330643A - Carbon black for black matrix - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a carbon black suitable for an insulating black matrix which can be used even under a high temperature treatment condition. SOLUTION: Carbon black is coated with a resin,
Next, carbon black for black matrix obtained by oxidation treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon black for an insulating black matrix, and more particularly to a carbon black for an insulating black matrix used for an optical color filter used in, for example, a color television, a liquid crystal color television and a camera. About 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 .mu.m, a liquid crystal substance is sealed therebetween, and a liquid crystal is fixed by a voltage applied between the electrodes. An 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 three color filters of red (R), green (G), and blue (B) corresponding to the three primary colors of light on one of the transparent electrode substrates, and applies a voltage to the transparent electrode. By adjusting the voltage, the transmission of the light of the liquid crystal is controlled to control the amount of light transmitted through the three color filters of R, G, and B, and color display is performed by adding the three primary colors.

The R, G, and B color layers are formed on a substrate on which a black matrix film for partitioning each color is provided in advance, or a black matrix film is formed after R, G, and B are formed. 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 electrode such as a liquid crystal driving electrode or a transistor such as a TFT (thin film transistor) provided on a substrate facing the color filter. It has the effect of doing. The black matrix of the color filter used for such a purpose can be roughly classified into two.

(1) A black matrix made of a metal film of Cr or the like processed by photolithography: a high resolution and a high light-shielding ratio, and an optical density (OD) of 3.0 or more can be easily obtained at a film thickness of about 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 displayed image is reduced due to the reflection of external light, and a bright object in the surroundings is reflected on the black matrix surface and overlaps the displayed image. It is easy for reflection to occur and image quality to deteriorate. In addition, there is a disadvantage that it is difficult to reduce the cost because the steps of sputtering and photolithography processing of the Cr film are long.

(2) An organic resin film in which a black pigment is dispersed is patterned by a photolithography method, a printing method, or a photoetching method, or a photosensitive resin film is patterned and then dyed with a black dye. Black matrix made of black organic resin film. Reflection of visible light is as low as several percent or less due to black, and metal image black matrix reduces the contrast of displayed images due to the reflection of external light and reflects surrounding bright objects. And the image quality is improved. However, there is a disadvantage that the light blocking ratio is low. That is, in the photolithography method, when the light blocking ratio is increased, the amount of exposure light reaching the interface with the substrate is reduced.
At 0, the amount of transmitted light reaching the substrate is 1/1000), and the pattern of the organic resin film is peeled off during development, so that a black matrix cannot be formed. If the amount of exposure is increased to avoid this, the pattern size is increased, and it is likely that a predetermined resolution cannot be realized. In addition, although the printing method and the photo etching method are slightly less restrictive than the photolithography method, the content of the black coloring material is limited. .
In the case of 0 μm and an optical density of 2.0, increasing the optical density to 3.0 results in a film thickness of 3.3 μm.) Black matrix may not be formed.

In general, a black matrix made of a black organic resin film has a thickness of 1 to 2 μm at an optical density of 2.0 to 2.5 compared to a black matrix made of a metal film.
When the film thickness exceeds 1.5 μm, the color filter, protective film, and transparent electrode are formed thereon, and the finished substrate has a surface flatness exceeding 0.5 μm, and is combined with the counter electrode substrate. When a liquid crystal display panel is used, color unevenness, white spots, brightness unevenness, and the like occur, and the display image quality deteriorates. Therefore, the thickness of the black matrix is 1 μm
It is extremely important that the thickness be 0.5 μm or less.

On the other hand, with respect to a transparent protective film and a transparent pixel electrode, for example, Japanese Patent Laid-Open No. 4-130401 discloses a conductive light-shielding pattern layer, a transparent insulating layer, a color filter pattern layer, a transparent protective film layer on a transparent substrate. A color filter with an electrode 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, improve the solvent resistance of the color filter, and further form a conductive light-shielding layer (black matrix) and a transparent conductive layer ( (Transparent electrode) for the purpose of electrical insulation.

However, recently, for the purpose of lowering the cost and further reducing the thickness of the color filter (liquid crystal display device), the transparent protective film and the transparent insulating film have been removed, and the smoothness and insulation that can be used for the color filter and the black matrix itself have been removed. There is a lot of research on giving sex. Further, the drying temperature after applying a black matrix or RGB resist is set to 22.
There has been a demand for increasing the temperature to 0 ° C. or higher, preferably to 250 ° C. or higher. That is, there is a strong demand for a black matrix that maintains insulation even after the resist-coated surface is treated at a high temperature. However, especially with respect to the insulating properties, as the main components of the black matrix, metal films such as chromium and chromium oxide and carbon powders such as carbon black and graphite are all conductive materials, the insulating properties under low-temperature heat treatment conditions Is extremely difficult, and new materials have been desired.

[0009]

SUMMARY OF THE INVENTION Based on such a viewpoint, the present invention provides a black matrix composed of a black light-shielding film having a high light-shielding rate and a low surface reflectance, which cannot be realized by the conventional method. It is an object of the present invention to provide a carbon black suitable for a color filter having a function of a transparent protective film and a transparent insulating film at the same time as a carbon black for an insulating black matrix which can be used even under a high-temperature processing condition. I do.

[0010]

The gist of the present invention is to provide a carbon black for an insulating black matrix obtained by coating carbon black with a resin and then oxidizing the same. Hereinafter, the present invention will be described in detail.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The carbon black to be coated with a resin in the present invention is not particularly limited, but the following carbon black is preferably used. Ash content 1.0% by weight or less, DBP absorption 140m
1/100 g or less of carbon black is preferred. The composition of the ash is an alkali metal such as Na, K, Ca or the like, an alkaline earth metal, or the like. When carbon black containing these is mixed with a resin or the like, the insulating property is reduced. This is Na
And ionic conductive substances such as K and Ca have high water absorption, so that the water absorption of the carbon black-resin composite increases,
As a result, it is considered that the insulating property is reduced.

The reduction of the ionic conductive material can be achieved by examining the raw material oil at the time of producing carbon black, examining the spray water used at the time of quenching, examining additives, and the like. It can also be achieved by washing or pickling carbon black produced from a production furnace. Further, it can also be achieved by combining the examination of the raw materials, spray water, additives and the like at the time of the above production with washing with water, pickling and the like. The content of the ionic conductive substance present in the carbon black is represented by the amount of ash remaining when the carbon black is calcined at 750 ° C. in air for 4 to 6 hours.
The ash content of the carbon black in the composition of the present invention is preferably 1.0% by weight or less, more preferably 0.1% by weight.
5% by weight or less.

When the DBP absorption amount measured by the JIS-K6221-A method exceeds 140 ml / 100 g, the blackness of the carbon black itself is reduced, and the density feeling when mixed and applied to a resin varnish for a black matrix is sufficient. In addition, the viscosity of the paste is increased, and a coating film having good smoothness may not be obtained. The DBP absorption amount is preferably 140 ml / 100 g or less, more preferably 120 ml / 100 g or less. The carbon black to be coated with a resin is preferably an oxidized carbon black, and the oxidizing method may be a method described later. The type of the resin to be coated is not particularly limited, but a synthetic resin is generally used, and a resin having a benzene nucleus in the structure has a stronger function as an amphoteric surfactant. Therefore, it is preferable from the viewpoint of dispersibility and dispersion stability.

Specific examples of the synthetic resin include a thermosetting resin such as a phenol resin, a melamine resin, a xylene resin, a diallyl phthalate resin, a glycol resin, an epoxy resin, and an alkylbenzene resin; polystyrene, polycarbonate, polyethylene terephthalate, and polybutylene terephthalate. , Modified polyphenylene oxide, polysulfone, polyparaphenylene terephthalamide, polyamideimide, polyimide, polyaminobismaleimide, polyethersulfopolyphenylene sulfone,
Thermoplastic resins such as polyarylate and polyetheretherketone can be used.

The coating amount of the resin on the carbon black is 1 to 30 watts based on the total amount of the carbon black and the resin.
t% is preferable, and if the amount is less than 1 wt%, only the same dispersibility, dispersion stability, and insulating properties as those of untreated carbon black may be obtained. On the other hand, if it exceeds 30 wt%, the adhesiveness between the resins is strong, and the resin becomes a dumpling-like mass.
Dispersion may not progress.

Further, the carbon black of the present invention can be obtained by coating the carbon black with a resin and then subjecting the carbon black to an oxidation treatment. Examples of the oxidation treatment method include gaseous oxidation such as nitrogen oxide, ozone, SO ₃ gas, fluorine gas, air oxidation that is brought into contact with and reacting with air in a high-temperature atmosphere, nitric acid, potassium permanganate, chlorous acid, and hypochlorous acid. There are liquid phase oxidation using sodium chlorate, aqueous bromine solution, ozone aqueous solution, hydrogen peroxide and the like, which can be achieved by using these alone or in combination of two or more.

The degree of the oxidation treatment is preferably set by utilizing a phenomenon in which the amount of adsorbed iodine decreases as the oxidation treatment of ozone or the like proceeds. Specifically, it is preferable that the rate of change of the carbon black coated with the resin with respect to the iodine adsorption amount is set to −5% or more. If the amount is less than -5%, the resistance when formed into a paint or the like does not easily increase, and it becomes difficult to obtain a preferable insulating black matrix. Here, the iodine adsorption amount is determined according to JIS-K-6221.

The reason why the resistance is greatly improved by performing an oxidation treatment after coating with a resin is not clear, but one of the reasons is that there is a bare carbon black surface which is not covered with the resin even in the resin-coated carbon black. However, it is also conceivable that the resistance becomes high because an insulating functional group is imparted to this portion. Still another reason is that the polymerization of the resin monomer covering the carbon black surface due to the oxidation treatment is progressing to become a more insulating resin film, or
It is considered that both of these reasons are involved.

The carbon black coated with the resin in this manner can be used as a light-shielding material for an insulating black matrix according to a conventional method, and a color filter containing the insulating black matrix as a component can be used according to a conventional method. Can be created. For example, in preparing the black matrix resist composition of the present invention, first, a coating solvent, a dispersant and carbon black,
0.5 hours using a bead mill, a paint shaker or a valve homogenizer using glass beads or zirconia beads having a diameter of 0.1 to several mm, and a three-roll mill.
By dispersing for 30 hours, the carbon black concentration becomes 10
A ~ 70 wt% dispersion is obtained. Next, a photopolymerization initiator composition, an ethylenic compound (adhesiveness improving agent for a developed image), an organic polymer substance (adhesiveness improving agent to a substrate), and the like are added to the dispersion, and the mixture is dispersed. Prepare the product.

The optimum compounding ratio in preparing the black matrix resist composition is as follows. The dispersant is 1 to 100% by weight based on carbon black. The photopolymerization initiator composition is 0.2 to 3% based on the black matrix resist composition excluding carbon black.
0% by weight, preferably 0.2 to 20% by weight The ethylenic compound accounts for 50 to 95% by weight, preferably 60 to 90% by weight, based on the black matrix resist composition excluding carbon black. 10 to 70% by weight, preferably 20 to 60% by weight, based on the black matrix resist composition excluding carbon black Carbon black is 35 to 80% by weight, preferably 50% by weight, based on the total solids in the resist composition. The solvent is adjusted so as to be in the range of 50 to 95% by weight, preferably 70 to 90% by weight, based on the whole of the photopolymerizable composition described above.

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

"Ethylenic compound" Ethylenically unsaturated compound 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 are used. 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 the compound (b).
As a specific example, dipentaerythritol hexaacrylate and the like can be mentioned as (A) a co-condensation monomer of bisphenol A and epichlorohydric (B).

"Organic polymer substance" Styrene, α-methylstyrene, benzyl (meth) acrylate, hydroxyphenyl (meth) acrylic acid, methoxyphenyl (meth) acrylic acid, hydroxyphenyl (meth) acrylamide, hydroxyphenyl (meth) 10-8 copolymer monomers having a phenyl group such as acrylsulfonamide
0 mol%, preferably 20 to 70 mol%, more preferably 30 to 60 mol%, and other (meth) acrylic acid is 2 to 50 wt%, preferably 5 to 40 wt%, more preferably The copolymer contained at a ratio of 5 to 30% by weight, or 2 to 50% by mole, preferably 5 to 40% by mole, more preferably 10 to 10% by mole based on all copolymerized monomers.
A reactant to which about 30 mol% of epoxy (meth) acrylate is added is desirable.

"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 include methyl isobutyl ketone, cyclohexanone, toluene, chloroform, dichloromethine, ethyl acetate, methyl lactate, ethyl lactate, methanol, ethanol, propanol, butanol, tetrahydrofuran and the like.

When the carbon black of the present invention is used, an insulating black matrix having a high light blocking ratio, 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 the carbon black with respect to the resin and the solvent constituting the insulating black matrix liquid were remarkably improved.

V. E. FIG. According to Ghoul et al. (Published in 1970, "Research and Application of Conducting Polymers"), the transfer of electric charge required when electricity flows is based on the surface of chains composed of filler particles and particles using thermal radiation heat. It is considered that the process is carried out mainly by the inside and, depending on conditions such as applied voltage and temperature, is carried out by a so-called tunnel effect of electron jump over a potential barrier.

According to the present invention, preferably, the surface is coated with a highly insulating resin using carbon black having a large number of surface functional groups, and the bare portion not coated with the resin is coated with an O ₂ or H ₂ functional group. By covering with, it acts to contain ionic substances such as Ca and Na, insulates the contact between conductors, and furthermore makes it impossible for electrons to jump due to the coating film. It is presumed to be achieved. Also, the reason why the resistance decreases little even when treated at high temperature and the insulation property can be maintained is that the oxidation treatment strengthens the bond between the carbon black and the coating resin, and as a result, the heat resistance of the resin itself is reduced. It is thought to improve.

[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 raw material oil, Na, C
a, coke oven gas was used for combustion using ethylene bottom oil having a small S content. Further, as the reaction stop water,
It was manufactured using pure water treated with an ion exchange resin.

When 500 g of this carbon black is used with an inner diameter of 30
cm, 60 cm long cylindrical kiln is installed in an electrothermal high-temperature bath capable of heating up to 200 ° C., and is rotated at 10 rpm while a model “O” manufactured by Wako System Control Co., Ltd.
10,000 ppm ozone generated by "R-4Z" was flowed at a flow rate of 5 L / min to cause a contact reaction with carbon black. 1. The temperature of the contact portion between ozone and carbon black is 50 ° C.
Treated for 3 hours. The basic physical properties of the obtained carbon black are as shown in Table 1.

The obtained carbon black (540 g) was mixed with pure water (14500 g) using a homomixer at 6,000 rpm.
The mixture was stirred at m for 30 minutes to obtain a slurry. The slurry was transferred to a vessel equipped with a screw-type stirrer, and while mixing at about 1,000 rpm, 600 g of toluene in which 60 g of an epoxy resin “Epicoat 828” manufactured by Yuka Shell Epoxy Co. was dissolved was added little by little. In about 15 minutes, the entire amount of the carbon black dispersed in the 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 10 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. Table 1 shows other basic physical properties. Next, 500 g of this carbon black was immersed in an inner diameter of 30 cm and a length of 60 c.
Then, the sample was placed in a cylindrical kiln having a flow rate of 5 mg / ozone and flowed at a flow rate of 5 L / min for 111 minutes. A mixture obtained by performing two batch treatments under the same conditions and uniformly mixing the whole was used as a carbon black for evaluation, and a resist composition for a black matrix was prepared by the following method. 1m
In a sand mill containing 300 g of zirconia beads of m diameter, 32 g of carbon black, 18 g of an organic polymer substance having the following structure, and propylene glycol / monomethyl ether acetate (hereinafter abbreviated as PGMEA) as a solvent.
150 g was added and mixed and dispersed at 2000 rpm for 10 hours to obtain a dispersion.

[0032]

Embedded image

Next, the black matrix resist composition was prepared by adding 90 g of zirconia beads having a diameter of 1 mm.
In a 40 cc mayonnaise bottle, 45 g of the above dispersion, 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 Kogaku KK) “SP-1509”), 1.13 g, 0.37 g of ethyl P-diethylaminobenzoate as a photopolymerization initiator composition, and 39 g of PGMEA were added, and the mixture was dispersed with a paint conditioner for 30 minutes to prepare a dispersion. The above black matrix resist composition obtained on a glass substrate (Corning Co., No. 7059, thickness 1.1 mm) subjected to high-pressure water washing, ultraviolet irradiation and ozone treatment was applied by a spin coating method, and then heated to 250 ° C. And 270 ° C. for 1.0 hour each to form a resist layer having a 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-2.

The powder resistance in the table is obtained by placing about 2 g of carbon black in a polytetrafluoroethylene container having an inner diameter of 2 cm with a brass electrode attached at the bottom, and a polytetrafluoride having a brass electrode at the tip. After covering with an ethylene rod, a load is applied at a rate of 0.2 mm / min using Tensilon, and the resistance at 50 kg / cm ² is measured with a high sensitivity tester. The powder resistance is calculated from the bulk of the powder under this load and the resistance value using the following equation. Powder resistance (Ω · cm) = Cross-sectional area of carbon black powder (cm ² ) × resistance value (Ω) / bulk height of carbon black powder (cm) The measurement was performed using a high resistance measuring device “Hiresta MCP-HT210” manufactured by Denshi Co., Ltd.

[Examples 2 and 3] The ozone treatment time after resin coating in Example 1 was 32 minutes in Example 2 and 2 minutes in Example 3
The same as in Example 1 except that the time was 33 minutes. Example 4 Example 4 was the same as Example 1 except that a high-molecular-weight polyurethane resin (average molecular weight: 13000) was used instead of the organic polymer having the structure of Chemical Formula 1. Comparative Examples 1 and 2 Comparative Example 1 is a resin-coated carbon black itself. Comparative Example 2 was a carbon black obtained by subjecting this carbon black to ozone treatment under the same conditions as in Example 1 for 15 minutes, and the others were evaluated as in Example 1.

[0036]

[Table 1]

[0037]

[Table 2]

Continued on the front page (72) Inventor Satoru Yasuda Satoru 138-1 Okunikocho Kokubunji, Himeji City, Hyogo Prefecture Inside (72) Inventor Taizo Mohri 138-1 Kokubunji Temple, Okuninocho Himeji City, Hyogo Prefecture In company

Claims (5)

[Claims] 1. A method of coating carbon black with a resin,
Next, carbon black for black matrix obtained by oxidation treatment. 2. The carbon black for a black matrix according to claim 1, wherein the resin has a benzene nucleus in the structure. 3. The coating amount of the resin is 1 to 30% by weight based on the total amount of the carbon black and the resin.
Carbon black for black matrix described in 1. 4. (Iodine adsorption value of carbon black coated with resin-Iodine adsorption value after oxidation treatment of carbon black coated with resin) / (Iodine adsorption value of carbon black coated with resin) The carbon black for a black matrix according to any one of claims 1 to 3, wherein the iodine value change rate calculated by the above is 5% or more. 5. A color filter having a black matrix, wherein the color filter is coated with a resin and then uses a black matrix in which carbon black that has been subjected to an oxidation treatment is used as a light-shielding material.