JP2017151290A - Color filter and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color filter that can effectively block leakage of light from a liquid crystal display that includes thick coloring pixels and thick overcoat layer.SOLUTION: A color filter is manufactured in the steps of: forming alignment marks on a translucent substrate with blue coloring pixels and material of blue coloring pixels; forming subsequently another coloring pixels; forming a first overcoat layer on the coloring pixels; forming a black matrix on the first overcoat layer by using the alignment marks; and forming a second overcoat layer.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a color filter used in a liquid crystal display device.

  The liquid crystal display device is configured by sandwiching a liquid crystal between a pair of translucent substrates. A driving circuit such as a TFT is formed on one translucent substrate (hereinafter referred to as a TFT substrate), and a black matrix, colored pixels, etc. are formed on the other translucent substrate to constitute a color filter. doing.

  A translucent substrate on which colored pixels are formed (hereinafter referred to as a color filter) is generally formed of three colors of red, green, and blue in a stripe or triangle arrangement on the translucent substrate. It is arranged in an appropriate pattern. First, a black matrix serving as a partition weir for partitioning colored pixels and preventing color mixture is formed on a light-transmitting substrate. As the black matrix material, a metal thin film or a black photosensitive resin composition is used, and a pattern is formed by a photolithography method.

  Subsequently, a green photosensitive resin composition is applied, and this is also patterned by, for example, stripes by a photolithography method to form green colored pixels. This process can be repeated for red and blue photosensitive resin compositions to obtain a color filter in which green, red and blue colored pixels are arranged.

  Here, in the upper part of the black matrix where adjacent colored pixels meet each other, the colored pixels run on the black matrix, thereby causing irregularities due to protrusions called horn steps. If a transparent electrode made of a transparent conductive layer is formed directly on the colored pixels above the black matrix, there is a high possibility that the electrical resistance value on the surface of the color filter will increase due to disconnection. Moreover, since stress tends to concentrate in such a part, in the heating / cooling process after the transparent electrode forming process of the transparent conductive layer, it is expected that the panel quality is deteriorated due to cracking in the transparent conductive layer. .

  Therefore, in the technique of Patent Document 1, the colored pixels are covered with a transparent overcoat layer to flatten the unevenness of the horn step, and a transparent conductive layer is formed on the overcoat layer.

JP 2002-228826 A

  However, when such a liquid crystal display device is used in a normally white mode and color display is performed by applying an electric field between the color filter and the pixel electrode of the TFT substrate, black display is performed on both adjacent pixels. In some cases, a light leakage region is generated in the liquid crystal layer due to a lateral electric field generated between the pixel electrodes.

  When the liquid crystal display device is viewed obliquely, adjacent color pixels are observed through the light leakage region of the liquid crystal layer, and thus there is a problem that visibility is deteriorated. This problem is solved by shielding the light leakage portion of the liquid crystal layer with a black matrix. However, the fact that the black matrix is formed in the layer below the colored pixel below the overcoat layer below the pixel electrode below the liquid crystal layer increases the difference in height between the liquid crystal layer and the black matrix. .

  Further, in recent years, in order to display a darker color in a liquid crystal display device, the thickness of the colored pixel tends to increase, and accordingly, the unevenness of the horn step of the colored pixel tends to increase. Therefore, the thickness of the overcoat layer that covers and flattens the horn step also tends to increase.

  Since the thickness of the overcoat layer and the colored pixels that cause a difference in height between the liquid crystal layer and the black matrix has increased, the light leakage region of the liquid crystal layer can be seen when the liquid crystal display device is viewed obliquely. The problem that visibility is deteriorated due to the observation of adjacent color pixels through the light leakage region is increasing.

  The present invention has been made in view of the above problems, and an object thereof is to provide a color filter capable of effectively shielding light leakage of a liquid crystal display device in which the thickness of a colored pixel and the thickness of an overcoat layer are large. There is.

In order to solve the above problems, the present invention provides:
A color filter in which a colored pixel layer including a plurality of colored pixels, a first overcoat layer, a black matrix, and a second overcoat layer are sequentially formed on a translucent substrate.

  The present invention has an effect that a color filter capable of effectively shielding light leakage of the liquid crystal display device can be obtained by this configuration.

  The present invention is the color filter described above, wherein a transparent electrode layer and a spacer are sequentially formed on the second overcoat layer.

  The present invention is the color filter described above, wherein a spacer is formed on the second overcoat layer.

  The present invention is also a method for manufacturing a color filter, the step of forming an alignment mark with a blue colored pixel and a material of the blue colored pixel on a translucent substrate, and then the step of forming another colored pixel. A step of forming a first overcoat layer on the colored pixels, a step of forming a black matrix on the first overcoat layer using the alignment marks, and a second step. A method for producing a color filter, comprising the step of forming an overcoat layer.

  In addition, the present invention is a method for manufacturing the above color filter, which includes a step of sequentially forming a transparent conductive layer and a spacer on the second overcoat layer, or a step of forming a spacer. This is a method for manufacturing a color filter.

  According to the color filter of the present invention, a color filter having a black matrix at a high position close to the height of the liquid crystal layer of the liquid crystal display device can be obtained, thereby obtaining a color filter capable of effectively shielding light leakage of the liquid crystal display device. effective.

  Further, the present invention provides a second overcoat layer on the black matrix as a base for forming the transparent conductive layer so that the black matrix does not directly touch the transparent conductive layer 5. This has the effect of improving the insulation between the transparent conductive layer on the overcoat layer and the black matrix.

  In particular, the present invention has a structure in which the black matrix is insulated from the transparent conductive layer 5 by the second overcoat layer. Therefore, a black matrix having a high carbon concentration and a high carbon concentration, which could not be used to deteriorate the insulation, is used. There is an effect that it is possible to construct a color filter having a black matrix with a high light shielding property.

It is sectional drawing (the 1) explaining the manufacturing method of the color filter of embodiment of this invention. It is sectional drawing (the 2) explaining the manufacturing method of the color filter of embodiment of this invention. It is sectional drawing (the 3) explaining the manufacturing method of the color filter of embodiment of this invention. It is sectional drawing (the 4) explaining the manufacturing method of the color filter of embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
<First Embodiment>
3B and 4 are sectional views of the color filter according to the first embodiment of the present invention.

  In the cross-sectional view of the color filter shown in FIG. 3, 1 is a translucent substrate, 2 is a colored pixel, which is formed on the translucent substrate 1 and divided into predetermined regions. Of the colored pixels 2, the blue colored pixels are distinguished from 2B, the red colored pixels are differentiated from 2R, and the green colored pixels are distinguished from 2G, and are denoted by reference numerals.

  In FIG. 3, 3 is a transparent first overcoat layer, which is formed on the colored pixels 2. Reference numeral 4 denotes a black matrix formed on the first overcoat layer 3, which shields the border between the colored sections of the colored pixels 2. A transparent conductive layer 5 made of ITO or the like is formed on the upper surface of the black matrix 4 or on the second overcoat layer 6 on the black matrix 4. PS is a photo spacer and is formed on the transparent conductive layer 5. These constitute a color filter.

  By manufacturing a color filter having this configuration, a color filter having a black matrix 4 having a height close to that of the transparent conductive layer 5 can be obtained. Thereby, there is an effect that a color filter capable of effectively shielding light leakage of the liquid crystal display device without widening the width of the black matrix 4 is obtained.

  Here, for example, a first overcoat layer 3 having a thickness of 1.5 μm is formed on the colored pixel 2 having a thickness of 2.5 μm, and a black matrix 4 having a thickness of 1.3 μm is formed thereon. Thereby, the unevenness of about 1 μm to 1.5 μm caused by the overlapping of the end portions of the color pixels 2B, 2R, and 2G having a film thickness of 2.5 μm is flattened to 0.3 μm or less.

  By forming the black matrix 4 on the first overcoat layer 3 flattened in this manner, the film thickness variation of the black matrix 4 generated when the black matrix 4 is formed directly on the colored pixels 2. Further, there is an effect that it is possible to eliminate the uneven line width in which the line width of the black matrix 4 is locally thin.

The material of the light-transmitting substrate 1 is inorganic glass such as quartz glass, borosilicate glass and soda glass, plastic substrate such as PET, PES, and PC, or silicon oxide, aluminum oxide, nitride on these glass substrate and plastic substrate. A film formed by depositing an inorganic thin film such as silicon or silicon oxynitride can be used depending on the purpose and application of use.

(Material for coloring pixel 2)
The material of the colored pixel 2 is composed of a plurality of colored pixels 2B, 2R, and 2G, and examples of the color include a combination of red, green, and blue (RGB) or a combination of yellow, magenta, and cyan (YMC). In addition, some of the colored pixels can be made transparent to increase the brightness.

  A first overcoat layer 3 is formed on the colored pixels 2, and a black matrix 4 is formed on the first overcoat layer 3. The black matrix 4 is obtained by, for example, applying a black photosensitive resin composition on the first overcoat layer 3 and drying it, then exposing to a predetermined pattern using a photomask, and performing development and post-baking. Form.

  The photosensitive colored resin composition for forming the black matrix 4 and the colored pixels 2 is produced by dispersing a pigment serving as a colorant, a photoinitiator, a polymerizable monomer, and the like in a transparent resin with an appropriate solvent.

An example of the raw material of the photosensitive colored resin composition that can be used in this embodiment will be described.
(Black matrix 4 shading material)
As the light shielding material of the black matrix 4, metal oxides such as carbon black, titanium oxide, and titanium oxynitride, pigments, and other known light shielding materials can be used. Moreover, in order to adjust the color tone of the light shielding layer, the following complementary color pigments may be mixed as necessary.

(Colored pigment of colored pixel 2)
Examples of the blue coloring composition include C.I. I. Pigment Blue 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 22, 60, 64, 80, etc., preferably C.I. I. Pigment Blue 15: 6 can be used. In addition, C.I. I. Pigment Violet 1, 19, 23, 27, 29, 30, 32, 37, 40, 42, 50 and the like, preferably C.I. I. PigmentViolet 23 can be used in combination.

  Examples of red coloring pixels or red coloring compositions for forming red pixels include C.I. I. PigmentRed 7, 9, 14, 41, 48: 1, 48: 2, 48: 3, 48: 4, 81: 1, 81: 2, 81: 3, 97, 122, 123, 146, 149, 168, 177 178, 179, 180, 184, 185, 187, 192, 200, 202, 208, 210, 215, 216, 217, 220, 223, 224, 226, 227, 228, 240, 246, 254, 255, 264 Red pigments such as 272, 279 can be used. A yellow pigment and an orange pigment can be used in combination with the red coloring composition.

  Examples of yellow pigments include C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 10, 12, 13, 14, 15, 16, 17, 18, 20, 24, 31, 32, 34, 35, 35: 1, 36, 36: 1, 37, 37: 1, 40, 42, 43, 53, 55, 60, 61, 62, 63, 65, 73, 74, 77, 81, 83, 86, 93, 94, 95, 97, 98, 100, 101, 104, 106, 108, 109, 110, 113, 114, 115, 116, 117, 118, 119, 120, 123, 125, 126, 127, 128, 129, 137, 138, 139, 144, 146, 147, 148, 150, 151, 152, 153, 154, 155, 156, 161, 162, 164, 166, 167, 168, 169, 170, 171, 172, 1 3,174,175,176,177,179,180,181,182,185,187,188,193,194,199,213,214, and the like. Examples of orange pigments include C.I. I. Pigment Orange 36, 43, 51, 55, 59, 61, 71, 73 and the like.

  Examples of the green coloring composition include C.I. I. Green pigments such as Pigment Green 7, 10, 36, and 37 can be used. The green coloring composition can be used in combination with the same yellow pigment as the red coloring composition.

  In combination with the above-described coloring composition or organic pigment, an inorganic pigment can also be used in combination in order to ensure good coatability, sensitivity, developability and the like while balancing saturation and lightness. Inorganic pigments include yellow lead, zinc yellow, red bean (red iron oxide (III)), cadmium red, ultramarine, bitumen, chromium oxide green, cobalt green and other metal oxide powders, metal sulfide powders, metal powders, etc. Can be mentioned. Furthermore, for color matching, a dye can be contained in a range that does not lower the heat resistance.

(First overcoat layer 3)
As the material of the first overcoat layer 3, a resin having a transmittance of preferably 80% or more, more preferably 95% or more in the wavelength region of 400 to 700 nm in the visible light region is used. For the first overcoat layer 3, for example, an acrylic resin, an epoxy resin, a vinyl ether resin, a polyimide resin, a propynyl resin, or the like can be used.

  Further, the first overcoat layer 3 is formed to have a thickness capable of ensuring flatness on the colored pixels 2 in the transmitted light region and protecting the colored pixels 2. For example, when the colored pixel 2 having a film thickness of 2.5 μm is formed, the unevenness of the colored pixel 2 of about 1 μm to 1.5 μm may occur, depending on the amount of overlap between the RGB patterns.

  For example, if the pattern of the black matrix 4 having a film thickness of 1.3 μm is formed directly on the colored pixel 2, the film thickness of the black matrix 4 varies due to the unevenness of the underlying colored pixel 2. If there is a portion where the height of the colored pixel 2 as a base is locally high, when the photosensitive resin composition for black matrix is applied, the surface height of the coating film is flattened so that The coating film thickness of the photosensitive resin composition for black matrix will become thin. When the coating film thickness of the photosensitive resin composition for the black matrix is thin, the development proceeds easily, so that the line width of the pattern of the black matrix 4 in that portion becomes locally narrow. It becomes the cause of.

  As the film thickness of the first overcoat layer 3 is increased, the surface flatness is improved. However, when the unevenness of the colored pixel 2 is about 1 μm to 1.5 μm, the first overcoat layer 3 has a film thickness of 1.5 μm. By forming the coat layer 3, the unevenness of the surface of the first overcoat layer 3 can be planarized to approximately 0.3 μm or less.

(Black Matrix 4)
On the first overcoat layer 3, a pattern of a black matrix 4 having a film thickness of 1.3 μm is formed. The black matrix 4 shields the border between the color sections of the colored pixels 2.

(Second overcoat layer 6)
A second overcoat layer 6 is formed on the black matrix 4. The second overcoat layer 6 can be omitted, and the transparent conductive layer 5 made of ITO or the like can be formed directly on the black matrix 4, but the second overcoat layer 6 can be formed. desirable. A second overcoat layer 6 having a thickness of 1.5 μm is formed on the black matrix 4. The second overcoat layer 6 can flatten the surface irregularities to approximately 0.2 μm or less.

  By forming a second overcoat layer 6 on the black matrix 4 as a base for forming the transparent conductive layer 5, the black matrix 4 is separated from the lower first overcoat layer 3 and the upper second overcoat layer 3. The transparent conductive layer 5 can be prevented from being directly touched by being sandwiched between the coat layers 6. Thereby, there is an effect that the insulating property between the transparent conductive layer 5 on the second overcoat layer 6 and the black matrix 4 is improved.

  As described above, since the black matrix 4 is insulated from the transparent conductive layer 5 by the second overcoat layer 6, a material having a high carbon concentration and a high light shielding property can be used for the black matrix 4. There is an effect that the light shielding property can be increased.

(Transparent conductive layer 5)
A transparent conductive layer 5 made of ITO or the like is formed on the second overcoat layer 6. The transparent conductive material constituting the transparent conductive layer 5 is not particularly limited, and a known material used for a conventional color filter, for example, ITO (indium tin oxide) is preferably used.

(Photospacer PS)
As a material constituting the photo spacer PS formed on the transparent conductive layer 5, a photosensitive negative resist having a heat flow property is preferably used. This photosensitive negative resist is, for example, an acrylic photosensitive resin composition mainly composed of an alkali-soluble resin, a photopolymerization initiator, and a polymerizable monomer. In order to further enhance the heat flow property, a prescription with a resin having a low TG (glass transition point) or a prescription for reducing the monomer amount may be used. Alternatively, a photosensitive positive resist having a heat flow property may be used.

(Production method)
Next, with reference to FIGS. 1-3, the manufacturing method of the color filter of this embodiment is demonstrated.

(Process 1)
First, the colored pixels 2 are formed on the translucent substrate 1 as shown in FIG. 1A as shown in FIG.

  The colored pixel 2 is formed by forming the colored pixel 2 by a coating method such as a slit coating method, a spin coating method, or a roll coating method, and then patterning by a photolithography method, an ink jet method, a gravure printing method, or a flexographic printing method. A method such as a method can be used.

  However, considering high definition, controllability and reproducibility of spectral characteristics, it is most desirable to form the colored pixels 2 by the photolithographic method as follows.

  That is, first, a blue negative photosensitive material dispersed on a translucent substrate 1 as shown in FIG. 1A in a suitable solvent together with a pigment, a photoinitiator, a polymerizable monomer, etc. in a transparent resin. After the resin composition is applied and dried, pattern exposure is performed using a photomask having an opening corresponding to the pattern of the blue colored pixels, and normal development and post-bake treatment are performed, as shown in FIG. The blue colored pixels 2B are formed.

  Here, it is desirable to form the blue colored pixel 2B first. By doing so, the alignment mark by the blue colored pixel 2B is formed first. The alignment mark made of the material of the blue colored pixel 2B is used as a reference for alignment of patterns to be formed after the second color. By doing so, since the visibility of the alignment mark by the blue colored pixel 2B is good, there is an effect of improving the recognition accuracy of the alignment mark read by the alignment camera of the exposure apparatus that exposes the pattern formed after the second color.

  Thereafter, by repeating the same procedure, a red colored pixel 2R is formed as shown in FIG. 1C, and then a green colored pixel 2G is formed as shown in FIG. 1D. In some cases, transparent pixels can also be formed.

  The coating film thickness of each color of the colored pixel 2 on the translucent substrate 1 is usually about 1 to 3 μm after pre-baking considering the spectral transmittance and the like. An alkaline aqueous solution is used as the developer. Examples of the alkaline aqueous solution include a sodium carbonate aqueous solution, a sodium hydrogen carbonate aqueous solution, a mixed aqueous solution of the two, or a mixture obtained by adding an appropriate surfactant to them. After development, washed with water and dried to obtain a colored pixel 2 of a specific color.

  In this way, in the colored pixel layer composed of the plurality of colored pixels 2 in which the blue colored pixel 2B is first formed, the end of the blue colored pixel 2B is the lowermost transparent portion than the ends of the colored pixels 2 of all other colors. It is formed on the optical substrate 1 side. That is, in the colored pixel layer, the end of the pattern of the blue colored pixel 2B is formed in close contact with the translucent substrate 1, and is formed below the end of the colored pixels of all other colors. is there.

(Process 2)
<Formation of first overcoat layer 3 (first planarization layer)>
Next, as shown in FIG. 1E, a transparent resin for the first overcoat layer 3 such as an acrylic resin, an epoxy resin, a vinyl ether resin, a polyimide resin, or a propynyl resin is formed on the colored pixel 2. Is applied, dried at 90 ° C. for 5 minutes, irradiated with light from a high-pressure mercury lamp, exposed, post-baked and cured to form the first overcoat layer 3.

(Process 3)
<Formation of black matrix 4>
Next, as shown in FIG. 2 (f), a black photosensitive resin composition is applied on the first overcoat layer 3, dried, and then exposed to a predetermined pattern using a photomask and developed. And the black matrix 4 is formed by performing post-baking.

  The film thickness of the black matrix 4 is desirably set to a desired film thickness by estimating the required optical density from the amount of carbon black contained, and is generally about 1 to 2 μm. The black matrix 4 can be formed by applying a coating method such as a spin coating method, a slit coating method, or a spinless method, followed by patterning using the photolithography method as described above, or using an inkjet method or a printing method. It is also possible to form a pattern directly using it.

(Process 4)
<Formation of Second Overcoat Layer 6 (Planarization Layer)>
Next, as shown in FIG. 2G, on the first overcoat layer 3 and the black matrix 4, a first resin such as an acrylic resin, an epoxy resin, a vinyl ether resin, a polyimide resin, or a propynyl resin is used. A transparent resin for the overcoat layer 3 is applied, dried at 90 ° C. for 5 minutes, exposed to light from a high-pressure mercury lamp, exposed, post-baked and cured to form the second overcoat layer 6.

(Process 5)
<Formation of transparent conductive layer 5>
Next, as shown in FIG. 3A, the transparent conductive layer 5 made of, for example, ITO is formed on the upper surface of the second overcoat layer 6.

  However, this step is omitted for a color filter for an IPS (In-Plane-Switching) type liquid crystal display device in which two electrodes are provided on the TFT substrate side and the transparent conductive layer 5 is not formed on the color filter side.

(Formation of photo spacer PS)
Next, a photo spacer PS is formed on the transparent conductive layer 5 as shown in FIG. 3B or on the second overcoat layer 6 as shown in FIG. 4 as follows. .

  That is, a photosensitive negative resist having a heat flow property is applied on the transparent conductive layer 5 or the second overcoat layer 6, and dried under reduced pressure and prebaked to obtain FIG. b) Alternatively, as shown in FIG. 4, a photosensitive resist material layer is formed on the upper surface of the transparent conductive layer 5. As an example, the pre-bake treatment conditions are 80 to 120 ° C., and the treatment time is 90 to 240 seconds.

  The photosensitive resist material layer is exposed to a pattern of a photo spacer PS by an exposure machine, developed with an alkaline developer, and an unexposed portion is removed. Thereafter, oven baking is performed to form the photo spacers PS on the transparent conductive layer 5 of the color filter or the second overcoat layer 6 as shown in FIG.

  Further, in a color filter for an IPS liquid crystal display device, a photo spacer PS as shown in FIG. 4 is formed on the second overcoat layer 6.

  The photo spacer PS is desirably formed above the first overcoat layer 3. The oven baking conditions are, for example, 220 ° C. to 240 ° C. and 15 minutes to 30 minutes.

DESCRIPTION OF SYMBOLS 1 ... Translucent substrate 2 ... Colored pixel 2B ... (Blue) colored pixel
2R ... (red) colored pixel 2G ... (green) colored pixel 3 ... first overcoat layer 4 ... black matrix 5 ... transparent conductive layer 6 ... second overcoat Layer PS ... Photo spacer

Claims (5)

  A color filter, wherein a colored pixel layer composed of a plurality of colored pixels, a first overcoat layer, a black matrix, and a second overcoat layer are sequentially formed on a translucent substrate.   The color filter according to claim 1, wherein a transparent electrode layer and a spacer are sequentially formed on the second overcoat layer.   The color filter according to claim 1, wherein a spacer is formed on the second overcoat layer.   A method of manufacturing a color filter, the step of forming an alignment mark with a material of a blue colored pixel and a blue colored pixel on a translucent substrate, the step of forming another colored pixel, Forming a first overcoat layer thereon, forming a black matrix on the first overcoat layer by aligning the positions using the alignment marks, and forming a second overcoat layer A process for producing a color filter comprising the step of:   5. The color filter manufacturing method according to claim 4, comprising a step of sequentially forming a transparent conductive layer and a spacer on the second overcoat layer, or a step of forming a spacer. Manufacturing method.