JPH10186125A - Ink for black matrix layer and production of color filter by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain ink for a black matrix layer which has a high optical density and sufficient hardness and has an adequate yield value by specifying the compounding ratios of black pigments and red pigments. SOLUTION: This black matrix contains a binder resin, the black pigments and the red pigments. The compounding ratio of the black pigments is 28 to 42 pts.wt. per 100 pts.wt. binder resin and the compounding ratio of the red pigments is 3 to 18 pts.wt. per 100 pts.wt. binder resin. The compounding ratio of the black pigments is 18 to 42 pts.wt. per 100 pts.wt. binder resin and the compounding ratio of the red pigments is 3 to 22 pts.wt. per 100 pts.wt. binder resin. A polyester-melamine resin, melamine resin, epoxy resin, etc., are usable for the binder resin. Carbon black, iron oxide, titanium black, etc., are usable for the black pigments. An anthraquinone system, perylene system and isoindolinone system are usable for the red pigments.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ink used for forming a black matrix layer of a color filter, and a method for manufacturing a color filter using the ink.

[0002]

2. Description of the Related Art In recent years, a liquid crystal display used as a display device in place of a cathode ray tube or the like has realized color display using a color filter. The color filter is usually red (R) patterned for each pixel,
A green (G) and blue (B) color filter layer and a light-shielding black matrix layer are formed on a transparent substrate. This black matrix layer is provided at the boundary between pixels, for example, and prevents light leakage between color filters and between pixels, and plays an important role in preventing color unevenness and increasing the contrast of color filters. Play.

With the recent improvement in image quality of liquid crystal displays, the black matrix layer must have (1) a sufficient light-shielding property, that is, a high optical density (OD value);
(2) It is required that the line width of the pattern is extremely fine, 10 to 40 μm, and (3) that the edge is sharp, the surface flatness and linearity are excellent, that is, the pattern shape is excellent. Have been.

Therefore, conventionally, a black matrix layer is formed by a method of forming a chromium thin film on a transparent substrate by sputtering and patterning by a photolithographic method, or by applying a photoresist colored with a black pigment on the transparent substrate. A patterning method using a photolithographic method has been used. However, in the above method, since the photolithography method is used, there are problems that a large amount of expensive photoresist is required, the manufacturing process is many and complicated, and the manufacturing cost is increased.

[0005] On the other hand, in order to solve the above-mentioned problem, it has been studied to use a printing method for manufacturing a color filter. There are various printing methods, but for the production of color filters, intaglio offset printing is preferred from the viewpoints of fine pattern reproducibility, pattern linearity, uniformity of ink film thickness and flatness. Used for In this intaglio offset printing method, an ink colored with a colorant is filled in the indentations of the intaglio, the ink is transferred from the intaglio to the blanket, and then the ink is further transferred to the transparent substrate, so that the color filter layer or the black A matrix layer is formed. That is, since this method does not require an expensive photoresist and simplifies the manufacturing process, it is promising as a method capable of realizing cost reduction of a color filter.

[0006]

However, when a color filter is manufactured by a printing method, the pattern shape tends to be reduced. In particular, an ink containing a black pigment such as carbon black is used for forming the black matrix layer. Generally, since the thixotropic property of such an ink is low, there is a problem that the edge of a printed pattern is rounded. Appears prominently.

[0007] In order to solve the problem of the pattern having a rounded edge and to form a black matrix layer having an excellent pattern shape by printing, the yield value of the ink, which is an index of thixotropy, must be 1200 dyn / cm ² or more. It is known that there should be. In order to increase the yield value of the ink, a method of blending an extender such as silica may be considered. In this case, however, the content of the black pigment such as carbon black decreases, and the optical density of the black matrix layer ( (OD value) is greatly reduced.
That is, the OD value required for the black matrix layer (specifically, the OD value for light having a wavelength of 540 nm) is 2.3 or more in an STN type or MIM type liquid crystal display (the transmittance for light having the above wavelength is about 0.3). 5% or less),
The TFT liquid crystal display has a transmittance of 3.0 or more (the transmittance is 0.1% or less), but when an extender is blended, the OD value cannot be achieved.

Therefore, in order to obtain the above OD value,
A method of blending a large amount of pigment is considered.
The hardness of the black matrix layer is low.
As a result, it is necessary in the manufacturing process of the color filter.
In other words, a pencil hardness of 4H or more cannot be achieved. Ma
In addition, if the amount of pigment
May be too high, for example, the yield value
Is 4000 dyn / cm ^TwoAbove, ink is printed
There is a problem that transfer is sometimes not performed well. Follow
To obtain the specified OD value and the ink yield value
Is 2500-4000 dyn / cm^TwoTo be in the range
In addition, it is necessary to set the blending amount of the pigment in the ink.

[0009] Carbon black excellent in light-shielding properties is usually used as a black pigment for the black matrix layer. However, carbon black reduces the electrical insulation of the black matrix layer. When a large amount of carbon black is blended as described above, it can be used when a volume specific resistance of 1.0 × 10 ⁶ Ω · cm or more is required, for example, as in a color filter used for STN type or MIM type liquid crystal displays. The problem of disappearing occurs.

Accordingly, an object of the present invention is to solve the above-mentioned problems, to form a black matrix layer having a high optical density and a sufficient hardness, and to provide an ink for a black matrix layer having an appropriate yield value. It is to provide. Another object of the present invention is to provide a black matrix layer ink that can form a black matrix layer having high optical density, sufficient hardness and excellent electrical insulation, and has an appropriate yield value. is there.

Still another object of the present invention is to provide a color filter capable of forming a black matrix layer excellent in optical density and hardness using the ink for a black matrix layer and realizing low cost. It is to provide a manufacturing method.

[0012]

Means for Solving the Problems In the process of solving the above-mentioned problems, the present inventors have repeated their studies focusing on the fact that the human eye has the highest sensitivity near a wavelength of 540 nm.
If a pigment showing light-shielding properties with respect to light in the wavelength region is used together with a black pigment, it is possible to form a black matrix layer having excellent light-shielding properties or sufficient hardness without using a large amount of black pigment. The present inventors have found a new fact that the ink can be obtained and has an appropriate yield value, and have completed the present invention.

That is, the first black matrix layer ink of the present invention contains a binder resin, a black pigment and a red pigment, and the compounding amount of the black pigment is 28 to 100 parts by weight of the binder resin.
42 parts by weight, and the compounding amount of the red pigment is 3 to 18 parts by weight based on 100 parts by weight of the binder resin.

Since the first black matrix layer ink has a yield value set in an appropriate range, a black matrix layer having an excellent pattern shape can be formed. Further, by using such an ink, a black matrix layer having an optical density with an OD value as high as 3.0 or more and a sufficient pencil hardness of 4H or more can be formed. Therefore, the first black matrix layer ink can be suitably used, for example, for forming a black matrix layer in a TFT type liquid crystal display.

Further, the second ink for a black matrix layer of the present invention contains a binder resin, a black pigment and a red pigment, and the compounding amount of the black pigment is based on 100 parts by weight of the binder resin. 18
The yield of the second black matrix layer ink in which the amount of the red pigment is 3 to 22 parts by weight with respect to 100 parts by weight of the binder resin is set in an appropriate range. Therefore, a black matrix layer having an excellent pattern shape can be formed. Also, by using such an ink, the OD
A black matrix layer having an optical density as high as 2.3 or more, a sufficient pencil hardness of 4H or more, and a sufficient electric insulating property can be formed. Therefore, the ink for the second black matrix layer is, for example, S
It can be suitably used for forming a black matrix layer in a TN type or MIM type liquid crystal display.

The red pigment used in the present invention can impart thixotropy to the ink for the black matrix layer, similarly to the extender pigment. On the other hand, wavelength 5
Since the light-shielding property at around 40 nm is high, the optical density (OD value) does not significantly decrease unlike the extender pigment even when it is contained in the black matrix layer ink. Also,
Since the red pigment has low conductivity, it can be included in the ink for the black matrix layer to reduce the content of the black pigment (particularly, carbon black), thereby improving the electrical insulation.

The method of manufacturing a color filter of the present invention comprises forming a color filter layer and a black matrix layer on a transparent substrate, and printing the ink for a black matrix layer of the present invention on a transparent substrate. And forming the black matrix layer. In the method for producing a color filter of the present invention, since the black matrix layer is formed using the black matrix layer ink of the present invention, the pattern is excellent, and has high optical density and sufficient hardness. A black matrix layer or a black matrix layer which is excellent in pattern shape and has high optical density, sufficient hardness and excellent electrical insulation can be formed.
Further, since the printing method is used for forming the black matrix layer, the cost of the color filter can be reduced.

In the method for producing a color filter of the present invention, printing of the ink for the black matrix layer is preferably performed by intaglio offset printing using a blanket whose surface is made of silicone rubber. That is, by using a blanket whose surface is made of silicone rubber, the transferability of the ink from the blanket to the transparent substrate is improved, and a black matrix layer having a more excellent pattern shape can be formed.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The black matrix ink of the present invention is a vehicle containing a binder resin, a black pigment and a red pigment. The binder resin,
It is preferable to have excellent properties such as heat resistance, light resistance, solvent resistance, chemical resistance, adhesiveness to a transparent substrate, dispersibility of a coloring agent, and the like.For example, polyester-melamine resin, melamine resin, epoxy resin , Epoxy-melamine resin and the like can be used. These resins are used alone or in combination of two or more. Further, a curing catalyst such as an acid catalyst may be appropriately blended in the resin for the purpose of adjusting the curing speed of the resin.

Examples of the black pigment include black pigments such as carbon black, iron oxide (iron black), titanium black, and iron sulfate. Among the above examples, it is preferable to use carbon black from the viewpoint of obtaining a high OD value. As the carbon black, any method such as a channel method, a furnace method, and a ramp method may be used.In particular, carbon black produced by the channel method has a uniform particle size and is dispersed in the binder resin. Since it has good properties, it is preferably used.

The particle size of the black pigment is 50 to 50% in primary particles.
Preferably it is in the range of 500 nm. If the primary particle diameter of the black pigment exceeds the above range, the dispersibility of the black pigment in the binder resin may be extremely poor, or projections may be formed on the surface of the black matrix layer. On the other hand, when the particle diameter is smaller than the above range, the stability in the resin is deteriorated, so that a problem such that the dispersibility is reduced occurs. In particular, when carbon black is used as the black pigment, if the particle size of the carbon black falls below the above range, the conductivity of the carbon black increases, and the electrical insulation of the black matrix layer decreases, which is not preferable.

As the red pigment, various conventionally known red pigments such as anthraquinone type, perylene type and isoindolinone type can be used. The particle size of the red pigment is preferably in the range of 100 to 10,000 nm in primary particles, as in the case of the carbon black.
The ink for a black matrix layer of the present invention contains the binder resin described above, a black pigment, a red pigment, and a solvent, if necessary, an extender pigment, and the like.
It is prepared by mixing with a mixer such as a kneader. Such inks preferably have a low viscosity. Specifically, the viscosity is suitably from 10 to 30,000 poise (P), preferably from 500 to 10,000 poise.

The amount of the black pigment and red pigment in the black matrix layer ink of the present invention is determined by the yield value (dyn / c) indicating the thixotropic property of the ink.
m ² ), the optical density (OD value) when the ink is cured,
Hardness when ink is cured (pencil hardness), Volume resistivity (Ω · c) indicating electrical insulation when ink is cured
m) are set to have predetermined values, respectively.

Among the above characteristics, the OD value and the volume specific resistance value are, for example, those for a TFT type liquid crystal display and those for a TFT type liquid crystal display.
The required value is different for the TN type or MIM type liquid crystal display. Therefore, the composition of the ink for the black matrix layer will be described separately for a TFT type liquid crystal display and an STN type or MIM type liquid crystal display.

(For TFT type liquid crystal display) In the color filter for TFT type liquid crystal display, the yield value of the ink: 1200 to 4000 dyn / cm ² , the OD value of the black matrix layer: 3.0 or more, Pencil hardness: 4H or more is required. The volume resistivity of the black matrix layer is not particularly limited.

As the black matrix layer ink satisfying the above characteristics, the content of the black pigment is from 28 to 42 parts by weight, preferably from 30 to 35 parts by weight, based on 100 parts by weight of the binder resin, and the content of the red pigment is Is 3 to 18 parts by weight, preferably 5 to 10 parts by weight, based on 100 parts by weight of the binder resin. (For STN or MIM liquid crystal display) STN
In the mold or a color filter for a MIM type liquid crystal display, the yield value of and inks: OD value of 1200~4000dyn / cm ² · black matrix layer: 2.3 or more black matrix layer pencil hardness: 4H or Black Matrix Volume resistivity of layer: 1.0 ×
It is required to be 10 ⁶ Ω · cm or more.

The black matrix layer ink which satisfies the above characteristics has a black pigment content of 18 to 32 parts by weight, preferably 25 to 30 parts by weight, based on 100 parts by weight of the binder resin, and a red pigment content of Is 3 to 22 parts by weight, preferably 10 to 20 parts by weight, based on 100 parts by weight of the binder resin. In any of the above-mentioned compositions, if the content of the black pigment falls below the specified range, a sufficient OD value may not be obtained, or the yield value of the ink may be reduced to lower printability. Conversely, when the content of the black pigment exceeds the specified range, the hardness of the black matrix layer decreases, the yield value of the ink becomes too large, the printability decreases, and the volume resistivity of the black matrix layer decreases. May be too low and the electrical insulation may be insufficient.

On the other hand, when the content of the red pigment falls below the specified range, a sufficient OD value cannot be obtained, the yield value of the ink becomes low, the printability decreases, and the volume resistivity of the black matrix layer decreases. The value may decrease. Conversely, if the content of the red pigment exceeds the specified range, a sufficient OD value may not be obtained, the yield value of the ink may be low, printability may be reduced, and the hardness of the black matrix layer may be reduced. There is.

Next, the method for manufacturing the color filter of the present invention will be described in detail. The method of manufacturing a color filter according to the present invention is a method for forming a color filter layer including, for example, three colors of red (R), green (G) and blue (B) and a black matrix layer for shading on a transparent substrate. In the method for producing a filter, the black matrix layer ink of the present invention is printed on a transparent substrate to form the black matrix layer. More specifically, the black matrix layer is formed by printing the black matrix layer ink on a transparent substrate and then curing the ink.

As described above, it is preferable to use the intaglio offset printing method for printing the black matrix layer. Intaglio substrates used for intaglio offset printing include:
For example, glass such as soda lime glass, non-alkali glass, quartz glass, low alkali glass, and low expansion glass;
Resins such as fluororesin, polycarbonate resin, polyethersulfone resin, polymethacrylic resin; stainless steel,
Metals such as copper and low expansion alloy invar are used. Among them, it is preferable to use soft glass such as soda lime glass in order to reproduce a fine pattern with high accuracy.

The recesses formed on the surface of the intaglio are formed according to the pattern of the black matrix layer. The depth of the recess is not particularly limited, but is usually 1 to 15 μm, preferably 5 to 10 μm, depending on the thickness of the black matrix layer.
It is set in the range of μm. The pattern of the black matrix layer is not particularly limited, but usually has a line width of 15 to 50.
A pattern having a lattice shape of μm is formed. The thickness of the black matrix layer is usually set in the range of 0.5 to 1.5 μm.

As the blanket used for printing the black matrix layer, various types of conventionally known blankets can be used. In particular, it is preferable to use a silicone blanket whose surface is made of silicone rubber from the viewpoint of obtaining an excellent pattern shape. . The transparent substrate of the color filter preferably has a high transmittance for light having a wavelength of 400 to 700 nm, for example, a glass substrate such as non-alkali glass, soda lime glass, and low alkali glass, and polyether, polysulfone, and polyarylate. A film is preferably used.

The ink for the black matrix layer printed on the transparent substrate is usually at 180 to 230 ° C. for 30 to 1
80-80 minutes, preferably 60-180 at 200-230 ° C.
It is cured by heating and drying for minutes. In the present invention, after a black matrix layer is formed on a transparent substrate, a color filter is formed by forming, for example, a color filter layer composed of three colors of red (R), green (G) and blue (B). Can be Further, the order of forming the black matrix layer and the color filter layer may be reversed.

In forming the color filter layer, it is preferable to use an intaglio offset printing method from the viewpoint of forming a fine pattern with an excellent pattern shape and reducing the cost of the color filter. As the color filter layer ink used to form the color filter layer, those prepared in the same manner as the above-described black matrix layer ink are used, except that a colorant according to the color of the color filter layer is used. .

The printing of the color filter layer may be performed in the same manner as the printing of the black matrix layer, except that a concave portion corresponding to the pattern of the color filter layer is formed on the surface of the intaglio plate.

[0036]

The present invention will be described below with reference to test examples. (Preparation of Ink for Black Matrix Layer) The components used in the ink for black matrix layer are as follows:
As shown in v).

(I) Binder resin: polyester-melamine-based resin (a product obtained by esterifying trimellitic acid and neopentyl glycol and adding a methylated melamine resin as a crosslinking agent) (ii) Black pigment: carbon black ( ("Special Black 4" manufactured by Degussa Co.) (iii) Red pigment: Chromophtal Red A3B (CI Pigment Red 177) manufactured by Ciba Geigy (iv) Solvent: High boiling point hydrocarbon having about 10 to 15 carbon atoms Test Examples 1 to 6 Carbon black was blended at a ratio shown in Table 1 with respect to 100 parts by weight of a binder resin, and a predetermined amount of a solvent was further blended to prepare an ink for a black matrix layer. In addition,
The viscosity of the ink was adjusted in the range of 500 to 1000 poise (P) (the same applies to the following test examples).

Test Examples 7 to 12 5 parts by weight of a red pigment was blended with 100 parts by weight of a binder resin, carbon black was blended in the ratio shown in Table 2, and a predetermined amount of a solvent was blended to prepare an ink for a black matrix layer. Was prepared. Test Examples 13 to 16 15 parts of red pigment was added to 100 parts by weight of binder resin.
Parts by weight were blended, carbon black was blended at the ratio shown in Table 3, and a solvent was blended in a predetermined amount to prepare an ink for a black matrix layer.

Test Examples 17 to 22 20 parts of a red pigment was added to 100 parts by weight of a binder resin.
Parts by weight were blended, carbon black was blended in the ratio shown in Table 4, and a solvent was blended in a predetermined amount to prepare an ink for a black matrix layer. Test Examples 23 to 26 25 parts of red pigment was added to 100 parts by weight of binder resin.
Parts by weight were blended, carbon black was blended in the ratio shown in Table 5, and a solvent was blended in a predetermined amount to prepare an ink for a black matrix layer.

(Formation of Black Matrix Layer) Using the inks obtained in Test Examples 1 to 26, a black matrix layer was printed by intaglio offset printing. That is, each of the above inks for a black matrix layer is printed on a transparent substrate (made of soda lime glass) by intaglio offset printing, and then heated at 200 ° C. for 120 minutes to cure the ink, thereby obtaining a thickness of 1. 3 μm, line width 3
A 0 μm lattice-like black matrix layer was formed.
In this printing, a blanket having a surface made of silicone rubber was used.

(Evaluation of Black Matrix Layer) The following items (a) to (c) were evaluated for the black matrix layer. (a) Thixotropy: Yield value of ink (dyn / cm
² ) Rheology's “Soli Liquid Meter MR50”
0 ". (b) Light-shielding property: Optical density (OD) for light of 540 nm
Value) from Olympus Corp. “OPS-SP”
-100 ".

(C) Hardness: The hardness (pencil hardness) of the black matrix layer was determined according to the method (testing machine method) described in JIS K 5400, “Pencil Scratch Value”. (d) Electrical insulation: The volume specific resistance (Ω · cm) of the black matrix layer was measured with “Ultra High Resistance Meter R8340A” manufactured by Advantest. The voltage at the time of measurement was 100 to 1000V.

Tables 1 to 5 show the above results.

[0044]

[Table 1]

[0045]

[Table 2]

[0046]

[Table 3]

[0047]

[Table 4]

[0048]

[Table 5]

As is evident from Tables 1 to 5, 28 to 4 parts of carbon black were added to 100 parts by weight of the binder resin.
In Test Examples 10, 11, 14 and 15 in which 2 parts by weight were blended and the red pigment was blended in the range of 3 to 18 parts by weight,
The yield value of the ink was 1200 to 4000 dyn / cm ² , the OD value of the black matrix layer was 3.0 or more, and the hardness of the black matrix layer was 4H or more. Such a black matrix layer ink is suitable for forming a black matrix layer in a color filter for a TFT type liquid crystal display, for example.

Test Examples 8 to 8 in which 18 to 32 parts by weight of carbon black were blended with 100 parts by weight of binder resin and 3 to 22 parts by weight of red pigment were blended.
At 10 and 18-20, the ink yield value was 1200
4,000 dyn / cm ² , the OD value of the black matrix layer is 2.3 or more, the hardness of the black matrix layer is 4H or more, and the volume resistivity is 1 × 10
It could be ⁶ Ω · cm or more. Such black matrix layer inks are, for example, STN type or MIM
Can be suitably used for forming a black matrix layer in a color filter for a liquid crystal display.

[0051]

As described in detail above, since the ink yield value for the black matrix layer of the present invention is set in an appropriate range and the thixotropy is good, it is possible to print with an excellent pattern shape. is there. In addition, the use of the above-described ink enables the formation of a black matrix layer having a high optical density, sufficient hardness, and also exhibiting excellent electrical insulation as required. Therefore, the ink for a black matrix layer of the present invention is a TFT type, STN
It can be suitably used according to various types in a liquid crystal display such as a liquid crystal display and a MIM type.

According to the color filter manufacturing method of the present invention, since the black matrix layer is formed by a printing method using the black matrix layer ink of the present invention, the black matrix layer having the above-mentioned characteristics is obtained. Can be formed, and cost reduction can be realized. Therefore, the method for manufacturing a color filter of the present invention is suitably used as a method for manufacturing a color filter corresponding to high image quality and low cost.

Claims (4)

[Claims] An ink for a black matrix layer containing a binder resin, a black pigment and a red pigment, wherein the amount of the black pigment is 100%.
28 to 42 parts by weight based on 100 parts by weight of the binder resin, and
An ink for a black matrix layer, which is 18 parts by weight. 2. An ink for a black matrix layer comprising a binder resin, a black pigment and a red pigment, wherein the amount of the black pigment is 100%.
18 to 32 parts by weight relative to 100 parts by weight of the binder resin, and
An ink for a black matrix layer, comprising 22 parts by weight. 3. A method for manufacturing a color filter, wherein a color filter layer and a black matrix layer are formed on a transparent substrate, wherein the black matrix layer ink according to claim 1 or 2 is printed on a transparent substrate. A method for producing a color filter, comprising forming a matrix layer. 4. The ink for a black matrix layer according to claim 1,
Using a blanket whose surface is made of silicone rubber,
The method for producing a color filter according to claim 3, wherein printing is performed by an intaglio offset printing method.