JPH0749415A - Manufacture of color filter - Google Patents

Abstract

PURPOSE:To provide a color filter which has a high light-shielding black matrix and also is excellent in surface flatness by applying a black matrix forming solution, after picture elements having oil repellency or water repellency to the black matrix forming solution have been formed on a light transmissible base. CONSTITUTION:Picture elements of a plurality of colors that have been patterned are laminated on a light transmissible base. The picture element has gaps in which a black matrix can be formed and also has such a characteristic that the oil repellency or water repellency to a black matrix forming solution is large. The black matrix forming solution is mixed with a light-shielding agent and is chiefly colored in black color; and when it is applied, in the picture element part, the solution is repelled and does not adhere to it, so that the solution can be applied to the picture-element gap parts where oil repellency or water repellency to the black matrix forming solution does not act. After drying, a desired color filter can be manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color filter used in a liquid crystal display device, and more particularly to a method of manufacturing a color filter for a liquid crystal display which has high display quality and is low in cost.

[0002]

2. Description of the Related Art Generally, color filters for liquid crystal displays are
Pixels of three primary colors of red, green and blue formed on a light transmissive substrate are composed of a large number of picture elements as one picture element. Between each pixel, stripe-shaped or grid-shaped light-shielding regions (generally black and called a black matrix) having a certain width are provided in order to enhance display contrast.

A conventional color filter utilizes a black matrix which has been patterned by a photolithography method in advance, and is often formed of a metal thin film having a fine pattern. The metals used for the black matrix include Cr, Ni, Al and the like, and as a forming method thereof, a vacuum thin film forming method such as a sputtering method or a vacuum evaporation method is widely used. Next, in order to form a fine pattern, a photoresist pattern is usually formed by a photolithography technique, and then the metal thin film is etched using the resist pattern as an etching mask. By this step, a fine pattern of the metal thin film that matches the fine pattern of the photoresist can be formed.

Further, as a method for forming pixels, it is general to use a photolithography technique.
In addition to a method of dyeing a dyeable medium, a method of using a pigment-dispersed photosensitive composition, an electrodeposition method using a patterned electrode, etc., a method of forming a colored portion by a printing method or an inkjet method as a low-cost manufacturing method. There is also.

[0005]

However, the black matrix formed of the metal thin film has a high manufacturing cost in the step of forming the metal thin film, which causes the price increase of the color filter itself. Further, since Cr, which is generally used as a metal thin film for the black matrix, has a high reflectance, C is used in a place where the external light is strong.
The light reflected from the r-plane is also strong, and there is a problem that the display quality is significantly impaired, especially when a color filter is incorporated in a transmissive display. In order to reduce this reflected light, a method of providing a layer such as chromium oxide between Cr and the light transmissive substrate has been proposed, but the manufacturing cost of the black matrix will be further increased, and the cost will be reduced. It is not preferable from the point of view.

Therefore, for example, a resin colored with a light shielding agent is patterned, or a dyeable resin is patterned and then dyed black to form a black matrix, and then pixels of a plurality of colors are formed. A method of manufacturing a color filter has been proposed. However, in these methods, it is necessary to increase the film thickness of the black matrix in order to obtain a sufficient light shielding property. However, in the conventional method of forming a color filter, the pixels are formed not only in the original pixel area portion but also in the light-shielding area portion, that is, on the black matrix,
Therefore, a difference occurs in the total film thickness between the original pixel region portion and the black matrix portion, and the flatness of the color filter surface becomes extremely poor. Therefore, there is a problem that it is very difficult to satisfy both the black matrix having a sufficient light shielding property and the good surface flatness.

The present invention was devised in view of the drawbacks of such a technique, and an object thereof is to produce a color filter having a black matrix having a high light-shielding property and excellent in surface flatness. To provide a method.

[0008]

The object of the present invention is as follows.
Having a black matrix gap on the light-transmissive substrate,
A color filter characterized by forming a pixel having an oil-repellent or water-repellent action on a black matrix forming solution and then applying the black matrix forming solution to form a black matrix in the pixel gap. It is achieved by the manufacturing method of.

That is, the present invention is intended to manufacture a black matrix for a color filter by the following manufacturing method. First, patterned pixels of a plurality of colors are stacked on a light transmissive substrate. This pixel has a gap so that a black matrix can be formed, and has a large property of oil-repelling or water-repelling action with respect to the solution for forming the black matrix. The black matrix forming solution is mainly colored black by mixing a light shielding agent, and is applied onto this. At this time,
Since the black matrix forming solution is repelled in the pixel portion and does not adhere to the pixel portion, the solution can be applied to the pixel gap portion which does not exhibit oil-repelling or water-repelling action with respect to the black matrix forming solution. After that, the desired black matrix can be manufactured by drying. In the manufacturing method of the present invention, it is possible to make the film thickness of the black matrix part equal to the film thickness of the pixel part by applying a predetermined amount of a solution containing a light-shielding agent mixed in a predetermined concentration, which is easy. It is possible to manufacture a color filter having excellent surface flatness. In addition, since the pixel has a relatively large film thickness, the light-shielding property of the black matrix can be made sufficiently high.

The details will be described below. First, the light transmissive substrate used in the present invention is not particularly limited, and a glass or plastic film or sheet is preferably used.

Next, pixels of a plurality of colors are formed on the light transmissive substrate. Pixels are first formed by applying a pixel forming solution on a light-transmissive substrate and stacking the colored layers by drying with hot air, and then patterning the colored layers using a photolithography technique. To do. Similarly, patterned pixels of a plurality of colors are formed on the light transmissive substrate.

The pixel used in the present invention has a sufficient oil-repellent or water-repellent action on the solution when a black matrix-forming solution containing a light-shielding agent is applied in the next step. It has a resilience so that it repels the forming solution and at least the solution does not remain on the pixel. That is, as a pixel,
The receding contact angle of the black matrix forming solution is 20 °
Or more, preferably 40 ° or more, more preferably 80 °
It is desirable to have the resilience as described above. Therefore, it is necessary for the pixel to impart a sufficient oil / water repellent action to the black matrix forming solution. That is, the pixel forming solution includes at least a colorant, a binder resin, a solvent, and a component that imparts oil repellency or water repellency to the black matrix forming solution. The colorant is dispersed or dissolved in the pixel forming solution, and the binder resin is dissolved before use. The component that imparts oil repellency or water repellency may also serve as the binder resin. In this case, a resin having a large oil repellency or water repellency is dissolved in the pixel forming solution before use. Also,
When various commonly used resins that do not have oil repellency or water repellency are used as the binder resin, disperse or dissolve a material having a large oil repellency or water repellency in the pixel forming solution. Can be used.

As the non-photosensitive resin having a large oil-repellent or water-repellent effect, a resin having a low interfacial energy and containing atoms such as silicon and fluorine is preferably used. For example, those having organic silicone in the main chain or side chain, silicone resin or silicone rubber containing a siloxane component having a chain structure or a cyclic structure, vinylidene fluoride, vinyl fluoride, ethylene trifluoride, etc. Further, a fluororesin such as a copolymer thereof or a copolymer with ethylene tetrafluoride or another polymer is also preferably used.

Further, an epoxy resin, an acrylic resin, a polyimide resin, a urethane resin, a polyester resin, a polyvinyl resin, gelatin, or the like which is not oil-repellent or water-repellent to the black matrix forming solution is usually used. When various non-photosensitive resins are used as binders, it disperses materials having a large oil-repellent or water-repellent effect,
Alternatively, a dissolved product can be preferably used. The material having a large oil-repellent or water-repellent effect is preferably a material having a low interfacial energy and containing atoms such as fluorine and silicon.
Materials having a large oil-repellent or water-repellent action containing a fluorine atom include polymers and oligomers made of tetrafluoroethylene, which are insoluble in a solvent and are suitable for being dispersed as fine particles in a repulsion layer. In addition to these, as the low molecular weight compound, those having a group containing a fluorine atom and a hydrophilic and / or lipophilic group in the molecule are also suitable, and examples of those having such a molecular structure include, for example, fluorine-based surfactants. What is known as is preferably used and is represented by the general formulas (1) to (6).

[Chemical 1] Furthermore, as solvent-soluble polymers and oligomers,
Suitable are vinylidene fluoride, vinyl fluoride, ethylene trifluoride and the like, copolymers thereof, or copolymers with tetrafluoroethylene and other polymers.

As a method for forming pixels, for example, a photosensitive resin layer for pattern formation is laminated on a light-transmissive substrate, and then a pixel forming solution is applied and dried to laminate a colored layer. After that, a method called a so-called lift-off method in which a photosensitive resin layer and a colored layer are simultaneously patterned by a photolithography method, or after stacking a colored layer and a photosensitive resin layer for pattern formation in this order, first, There is a method in which the photosensitive resin layer is patterned by photolithography, the colored layer is then etched using the patterned photosensitive resin layer as a mask, and then the photosensitive resin layer is removed.

Photosensitive resins for pattern formation include photodegradable resins, photocrosslinkable photosensitive resins, and photopolymerizable resins. Positive resists for manufacturing ICs, LSIs, etc.,
What is used as a negative resist or a printing plate material can be preferably used. Examples of the photodegradable resin include those in which a naphthoquinonediazide compound is mixed with a cresol novolac resin, and as the photocrosslinking photosensitive resin, a monomer having an ethylenically unsaturated bond, an oligomer,
A photosensitive composition containing a polymer and an initiator that generates a radical by ultraviolet rays as a main component, a photosensitive polyamic acid solution, and the like are preferably used.

In addition to this, as a method of forming pixels,
A method of obtaining a pixel by directly applying a photosensitivity-imparting solution as a binder resin to a pixel forming solution on a light-transmissive substrate, drying it, and laminating a coloring layer, and then directly patterning this by a photolithography method. Is also available. As the photosensitive resin having a large oil-repellent or water-repellent action, the above-mentioned photosensitive resin for pattern formation, particularly, a monomer, an oligomer or a polymer having an ethylenically unsaturated bond, and an initiator which generates a radical by ultraviolet rays, A photosensitive composition containing as a main component,
A photo-crosslinking photosensitive resin such as a photosensitive polyamic acid solution in which a material having a large oil-repellent or water-repellent effect is similarly dispersed or dissolved, or a resin having a large oil-repellent or water-repellent effect is made photosensitive. A photosensitive resin having a low interfacial energy and containing an atom such as silicon or fluorine, which has organic silicone in the main chain or side chain, or a fluororesin is preferably used.

When a pixel having a large oil-repellent or water-repellent effect is dispersed or dissolved in a photosensitive or non-photosensitive resin to form pixels, a sufficient heat treatment is applied before applying a solution containing a light-shielding agent. Then, it is effective to deposit a material having a large oil repellency or water repellency on the surface of the pixel.
The heat treatment temperature is preferably not lower than the glass transition temperature of the photosensitive and non-photosensitive resins and the material having a large oil-repellent or water-repellent action, and is usually 100 ° C. or higher, further preferably 150 ° C. or higher, and more preferably 200 ° C. or higher. . The upper limit of the heat treatment temperature is the temperature at which a material having a large oil repellency or water repellency is thermally decomposed.

The colors of the pixels are usually red, blue and green, and are colored with a coloring agent. As the colorant used for the pixel, an organic pigment, an inorganic pigment, a dye or the like can be preferably used. As the organic pigment, a phthalocyanine-based pigment,
Azireki series, condensed azo series, quinacridone series, anthraquinone series, perylene series, perinone series and the like are preferably used.

As a method of dispersing or dissolving a colorant or a material having a large oil-repellent or water-repellent action, a known technique can be used, and a colorant, a material having a large oil-repellent action or a water-repellent action can be used in a solvent. Are mixed and dispersed in a disperser such as a ball mill, or dissolved by a stirrer.

The coloring layer can be applied by dip coating,
In addition to the roll coater, spin coating methods such as whalers and spinners are preferably used.

As a method for processing the colored layer into a pixel pattern, usually, a photolithography method is used, and after exposing from the colored layer side using an optical mask, development processing is performed to form pixels in a desired pattern. In this case, for the colored layer, a negative or positive photosensitive material can be used.

The shape of each pixel is generally patterned in a stripe shape, a mosaic shape, a triangle shape, or the like. Also, between each pixel is usually 10 to 100 μm.
A space of a certain degree is provided, and a black matrix is formed in the pixel gap in a later process.

As a light source used when exposing the photosensitive resin, a high pressure mercury lamp, a carbon arc lamp, an ultraviolet fluorescent lamp, a xenon lamp and the like are generally used. After completion of exposure, development is performed. By the development, the unexposed portion is removed, and only the exposed portion remains on the light transmissive substrate. For development, dip in a developing solution,
It can be performed by a known method such as rinsing, ultrasonic cleaning, and drying. As the developing solution, for example, for an alkali developable resin, an aqueous solution of an inorganic alkali such as sodium carbonate, sodium hydroxide or potassium hydroxide or an organic alkali such as ethanolamine is preferably used.

Next, a light-shielding agent is mixed in, and a black matrix forming solution which is mainly colored black is applied.
Pixels have a large oil-repellent or water-repellent property with respect to the black matrix forming solution. Therefore, the black matrix forming solution is repelled in the pixel portion and thus is not applied, and only in the pixel gap portion. A black matrix forming solution can be applied.

As the light-shielding agent, inorganic and organic pigments,
Dye, metal powder, metal oxide, etc. are preferably used,
A mixture of carbon black, titanium black and pigments of red, blue and green is particularly preferable.

The black matrix forming solution needs at least a light-shielding agent and a solvent for dissolving or dispersing the light-shielding agent. In addition to this, in order to further enhance the oil-repellent or water-repellent action with the resin serving as a binder and the pixel. Various additives can be added for the purpose of improving the leveling property. In order to enhance the oil repellency or water repellency, the surface tension of the solution containing the light shielding agent is preferably high, and for that purpose, it is preferable to use a polar solvent such as water having a high surface tension. Further, the higher the fluidity of the solution in which the light-shielding agent is mixed, the more effectively the oil repellency or water repellency acts. The viscosity of the solution is preferably 500 CP or less, more preferably 10 CP.
It is 0 CP or less, more preferably 50 CP or less.

As a method of dispersing or dissolving the light-shielding agent, a known technique can be used. The light-shielding agent is mixed with a solvent and dispersed in a dispersing machine such as a ball mill or dissolved by a stirring device. As a coating method, a dip coating, a roll coater, a whaler, a spinner, or the like is preferably used. Of these, spin coating methods such as dip coating, whaler, and spinner are particularly preferable because the coating amount of the black matrix forming solution is made uniform on the substrate during coating, and thus the black matrix has excellent film thickness uniformity.

After that, the desired black matrix is manufactured by drying in a hot air oven, a hot plate or the like. According to the manufacturing method of the present invention, the film thickness of the black matrix portion can be made close to the film thickness of the pixel portion by applying a predetermined amount of a solution in which a predetermined amount of the light shielding agent is mixed, and the surface can be easily flattened. A color filter having excellent properties can be manufactured. Moreover, since the film thickness of the pixel is relatively large, the light-shielding property of the black matrix can be made sufficiently high.

When the black matrix is formed by the above-mentioned coating method, a light shielding part similar to the black matrix part is formed outside the black matrix part formed in the pixel and the pixel gap. Generally, a frame-shaped light-shielding portion is formed adjacent to the peripheral side of the black matrix formed in the pixel and the pixel gap, and further, there is a portion outside of which a light-shielding portion is not required to be formed. The frame-shaped light-shielding part is provided to prevent light from leaking from the edge of the screen when cells are assembled and to provide a clear image.
It can be prepared by coating a solution for forming a black matrix. Further, for the portion which does not require the formation of the light-shielding portion on the outer side thereof, a method of providing a layer having a high oil-repellent or water-repellent action so as to prevent the adhesion by a similar method, and removing by a photolithographic etching method or the like in a later step It can be realized using the method.

The method of forming the black matrix after forming the pixels of each color has been described above. Of course, after forming a desired black matrix, the resilience of the pixels may be removed. As a method of removing the repulsion, heat treatment at a high temperature is performed to alter the component that imparts oil repellency or water repellency,
A method of degrading the oil-repellent or water-repellent effect by decomposition or the like, a method of extracting a component imparting the oil-repellent or water-repellent effect with a solvent, a method of laminating a resin layer having no oil-repellent or water-repellent effect on a pixel Etc. can be used.

Thereafter, if necessary, a top coat layer, I
The TO transparent electrode, the alignment film and the like are laminated by a known method. However, according to the manufacturing method of the present invention, the step difference between the pixel portion and the black matrix portion can be easily reduced by adjusting the solid content concentration and the coating amount of the black matrix forming solution, so that the top coat layer is omitted. This is particularly effective for improving the production yield and reducing the cost.

The present invention will be specifically described below with reference to examples.

[0034]

【Example】

Example 1 Color Index No.73905 Pig as red, green and blue pigments, respectively
quinacridone pigment shown in ment Red 209, Color In
dex No.74265 Pigment Green 36 Phthalocyanine green pigment represented by Color Index No.74160 Pigment Blu
A phthalocyanine blue pigment represented by e 15-4 was prepared. Red, green, and blue pigments of 5.4, 5.4, and 4.
8 parts were mixed and dispersed to obtain three kinds of pixel forming solutions of red, green and blue.

Photosensitive composition Polymer containing styrene / methyl methacrylate / methacrylic acid copolymer (copolymerization ratio 3/3/4) to which glycidyl methacrylate is added 8.4 parts by weight Trimethylolpropane triacrylate 3.0 parts by weight Epoxy acrylate 2.0 parts by weight "Irgacure" 369 (manufactured by Ciba-Gaigi) 0.6 parts by weight "Irgacure" 907 (manufactured by Ciba-Gaigi) 0.6 parts by weight Trithiophosphite 0.4 parts by weight Fluorosurfactant (To Chem Products Co., Ltd., "EFTOP" EF-123A-1) 0.7 parts by weight Fluorine-based surfactant (Dainippon Ink and Chemicals, Inc., "MEGAFAC" F-179) 3.5 parts by weight 2-Butoxyethanol 77 0.0 parts by weight First, a green pixel having the above composition is formed on a light-transmissive glass substrate. The coating solution was spin-coated with a spinner and dried in hot air at 80 ° C. for 10 minutes to obtain a colored layer. Thereafter, pattern exposure was performed from above with a high pressure mercury lamp using a mask, and development was performed with an alkaline developer of 2-aminoethanol to form stripe-shaped green pixels with a width of 60 μm and a pitch of 300 μm, and cured at 140 ° C. for 30 minutes. . The thickness of the green pixel was 1.5 μm. In the same manner, stripe-shaped red and blue pixels were formed so that the pixel intervals of the three colors were 40 μm. Further, it was heat-treated at 150 ° C. for 30 minutes to obtain a pixel having an oil repellency against the following black matrix forming solution. Black matrix forming solution Styrene / methyl methacrylate / methacrylic acid copolymer (copolymerization ratio 3/3/4) polymer with glycidyl methacrylate added 8.4 parts by weight trimethylolpropane triacrylate 3.0 parts by weight epoxy acrylate 2.0 parts by weight "Irgacure" 369 (manufactured by Ciba-Gaigi) 0.6 parts by weight "Irgacure" 907 (manufactured by Ciba-Gaigi) 0.6 parts by weight Trithiophosphite 0.4 parts by weight Carbon Black (Mitsubishi Chemical Co., MA -100) 5.8 parts by weight 2-butoxyethanol 77.0 parts by weight Next, a solution for forming a black matrix is spin-coated on the pixel forming surface side with a spinner, and dried with hot air at 80 ° C. for 10 minutes.
Subsequently, curing was performed in hot air at 250 ° C., and a black matrix having a thickness of about 1.5 μm was provided in the pixel gap. The receding contact angle of the black matrix forming solution with respect to the pixel was 25 °. A color filter having an OD of the black matrix of 3.5 or more and excellent in light-shielding property, and having a surface step difference of 0.3 μm or less between the black matrix and pixels and having excellent surface smoothness was obtained. Example 2 In the same manner as in Example 1, three types of pastes of red, green and blue were obtained. The green paste is applied on a light-transmissive glass substrate, dried, and then subjected to a photolithography method to form a vertical 125
The width is 145 μm and the lateral pitch is 456 μm.
m, and green pixels in a triangle array arranged at a vertical pitch of 172 μm were formed and cured. The thickness of the organic colored layer was 1.5 μm. Similarly, the red and blue pixels are
It was formed so that the pixel spacing of red, blue and green was 27 μm. Further, it was heat-treated at 150 ° C. for 30 minutes to obtain a pixel having a water-repellent action with respect to the following black matrix forming solution.

The solution for forming a black matrix is 5 parts by weight of carbon black, 5 parts by weight of a surfactant "New Coral" 710F (manufactured by Nippon Emulsifier Co., Ltd.), water and 79 parts by weight.
10 parts by weight of a melamine resin (Sumitomo Chemical Co., Ltd., "Sumiresin M-3"), a curing agent, after adding 10 parts by weight of glass beads and dispersing for 10 hours using a homogenizer (AM-11 by Nippon Seiki Co., Ltd.) It was prepared by mixing 1 part by weight (“Sumitex Accelerator” ACX manufactured by Sumitomo Chemical Co., Ltd.).
The black matrix forming solution is applied to the pixel forming surface with a spinner, dried in hot air at 80 ° C. for 10 minutes, and then 1
After curing in hot air at 50 ° C. for 30 minutes, a black matrix having a thickness of about 1.5 μm was provided in the pixel gap. The receding contact angle of the black matrix forming solution with respect to the pixel was 35 °. A color filter having an OD of the black matrix of 3.5 or more and excellent in light-shielding property, and having a surface step difference of 0.3 μm or less between the black matrix and pixels and having excellent surface smoothness was obtained.

[0037]

According to the present invention, since the color filter is manufactured as described above, it is possible to easily form the black matrix in the gap between the pixels and to obtain the color filter having excellent surface smoothness. Further, according to the present invention, the thickness of the black matrix can be made as thick as the thickness of the pixel, and a black matrix having a high light shielding property can be obtained.

Claims (1)

[Claims] 1. A pixel having a black matrix gap and having an oil-repellent or water-repellent action on a black matrix forming solution is formed on a light transmissive substrate, and then the black matrix forming solution is applied. By forming a black matrix in the pixel gap by performing the above, a method for manufacturing a color filter.