JP2824711B2 - Method of forming light-shielding pattern - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a light-shielding pattern having a high optical density and having high flatness and no wrinkles even at high temperatures. The method of the present invention is particularly useful for producing a color filter used for a liquid crystal display or the like.

[0002]

2. Description of the Related Art Color filters used in color liquid crystal displays are prepared by dyeing, pigment dispersion, printing, and the like.
Methods such as a transfer method have been considered. In any case, the positional accuracy of each colored pattern (for example, red, green, blue, and black) is very important. In particular, a light-shielding pattern, a so-called black matrix, must be positioned without gaps between other colored patterns. No. Therefore, at present, the black matrix is formed so as to have some overlap with other colored patterns. Black matrix is C
Although it may be formed by a vapor deposition film or the like, the cost is high.
As described in JP-A-35417, use of a photosensitive resin having a pigment such as carbon black has been considered. However, in this case, since the light shielding ability of the black matrix is proportional to the thickness of the black matrix, a film thickness of about 2 μm is required to obtain a high light shielding ability. Therefore, the overlapping part of the black matrix and other colored patterns becomes a considerable protrusion,
This was a problem when the demand for flatness was severe. Furthermore, when a photocurable resin having this thickness is used, light hardly reaches the lower portion of the resin layer, and thus the resin is in an uncured state.
When development is performed in this state, a desired black matrix pattern is formed, but when left at room temperature or higher, the difference in thermal expansion coefficient between the cured part and the uncured part on the surface of the pattern pixel seems to be the main cause. In some cases, wrinkles occurred and the pattern density became uneven. In particular, in the case of a color filter, this wrinkle occurs remarkably during processing such as post cure.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to have high flatness and to prevent wrinkles even when processed at high temperatures.
An object of the present invention is to provide a method for forming a light-shielding pattern (BM layer) having excellent light-shielding properties. The method of the present invention is particularly useful for making color filters.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to form a photopolymerizable light-shielding material layer directly on a substrate or on a substrate on which a single or a plurality of pixel patterns are formed.
After forming a light-shielding pattern by developing, if necessary, the flatness is increased by side etching described later, and thereafter, the entire surface is exposed through at least the substrate before wrinkles due to heat are generated.

Hereinafter, the present invention will be described in detail. In the method of forming a light-shielding pattern according to the present invention, in the photopolymerizable light-shielding material layer colored black used for forming the light-shielding pattern, light does not sufficiently reach the inside during exposure, and the degree of polymerization of a portion far from the surface is low. To provide a multicolor pattern which effectively prevents wrinkles due to lowness and has high flatness. That is, first, by patterning the entire surface through at least the substrate after patterning, photopolymerization is promoted in a portion where the degree of polymerization is insufficient by pattern exposure alone, the degree of polymerization in the light-shielded pattern pixel is leveled, and the post- Even if curing is performed, a state in which the coefficient of thermal expansion is substantially uniform can be created. The method of the present invention is particularly effective when the optical density of the photopolymerizable light shielding layer is about 2.0 or more.

Next, a preferred method for forming a multicolor pattern using the present invention will be described. First, red (R), green (G), and blue (B) pixel patterns are formed on a transparent glass substrate. The formation method can be any of conventional dyeing methods, printing methods, electrodeposition methods, electrodeposition transfer methods, transfer methods, pigment dispersion methods, and the like. Next, a photopolymerizable light-shielding material layer is provided on the entire surface. As a method, it is possible to use a printing method such as a pigment dispersion method or a transfer method, and in some cases, a screen printing method. Next, pattern exposure is performed from the front side through a photomask designed to fill at least the R, G, and B pixels.
The exposure amount at this time is determined according to the specifications of the mask to be used. Specifically, the light-transmitting region of the mask and each R,
It is determined by the relative relationship with the gap area between the G and B pixels, and the light exposure becomes smaller as the light transmitting area is larger than the gap area. Due to this, a portion where the curing reaction of the surface is insufficient is formed around the light-shielding portion pixel, and after development, the light-shielding material overlaps a part of each of the R, G, and B pixels and has a projection having a thickness of several μm. A light shielding pattern is formed.

In the case where the flatness of the surface is strict, as in the case of a color filter, the presence of this projection is a major drawback and must be removed. In the present invention, the operation of removing the overlapping portion between the light-shielding material pattern and the pixel pattern of another color is referred to as “side etching”. The side etching may be performed by, for example, treating the light-shielding material layer with a developing solution different from the developing solution after developing the light-shielding material layer, or extending the developing time required to form a normal pattern. At the time of these operations, it is also effective to apply rubbing or the like with a brush.

In the method of the present invention, the amount of exposure for patterning the light-shielding material layer depends on the light-shielding layer pattern, R, G,
It is necessary to control the width of the overlapping portion with the B pixel to be in the range of about 0.5 μm to about 10 μm. About 0.
If the thickness is less than 5 μm, it takes time to align the mask, so that the productivity is reduced. If the thickness exceeds about 10 μm, the side etching property is deteriorated, which is not preferable. As the light source, a known light source such as an ultra-high pressure mercury lamp, a xenon lamp, and an argon laser can be used depending on the photosensitivity of the photopolymerizable light-shielding material.
This exposure amount is an amount that is completely insufficient to sufficiently polymerize the entire light shielding material layer.

In the method of the present invention, before pattern exposure,
Before the development step or the side etching step, the back surface may be exposed to prevent pinholes. On this occasion,
By selecting the maximum exposure amount so that the portion of the photopolymerizable light-shielding material layer on the side opposite to the exposure surface of these pixels is not insoluble in the developer by the light transmitted through the R, G, and B pixels. The entire surface is exposed. With this exposure amount, the occurrence of wrinkles described above cannot be prevented.

These exposures can be performed in a vacuum or in a non-oxygen atmosphere such as nitrogen gas or argon gas, or can be heated before, during, or after exposure to the extent that wrinkles do not occur.

The above method will be described later in detail.

In the method of the present invention, a light-shielding pattern may be first formed on a substrate, and a multicolor pattern may be formed thereon. Also in this case, it is difficult to sufficiently polymerize the light shielding material layer only by exposure from the surface, and it is necessary to expose through the substrate in order to prevent wrinkles from occurring.

The photopolymerizable light-shielding material used in the present invention is a material obtained by dispersing or dissolving carbon black, a black mixture of a black pigment and a combination of a plurality of color pigments or a black dye in the photopolymerizable composition. A photopolymerizable composition in which carbon black, a black pigment, or a pigment mixture is dispersed is superior in providing a light-shielding layer having excellent heat resistance and light resistance. The photopolymerizable resin composition includes those which can be developed with an aqueous alkali solution and those which can be developed with an organic solvent, but those which can be developed with an aqueous alkali solution are preferable from the viewpoint of safety and the cost of the developing solution. The photopolymerizable composition developable with an aqueous alkali solution contains, as main components, a binder containing a carboxylic acid group, a polyfunctional acrylic monomer, and a photopolymerization initiator. Preferred photopolymerizable light-shielding materials are described in JP-A-1-15224.
No. 49, carbon as a pigment,
Including titanium carbon and iron oxide, each alone or in a mixture, as polyfunctional acrylic monomers, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, tetramethylene Glycol di (meth) acrylate, propylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, 1,4-hexanediol di (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meta) ) Using (meth) acrylates such as acrylate,
As a carboxylic acid group-containing binder acrylic acid, unsaturated organic acid compounds such as methacrylic acid and methyl acrylate,
The composition contains a copolymer of an unsaturated organic acid ester compound such as ethyl acrylate or benzyl methacrylate, and contains a halomethyloxadiazole-based compound or a halomethyl-s-triazine-based compound as a photopolymerization initiator. The preferred content of each component,
Pigments, expressed as% by weight in total solids, range from 10% to 50%.
%, Polyfunctional acrylate monomer from 10% to 50%,
The content of the carboxylic acid group-containing binder is 20% to 60%, and the content of the photopolymerization initiator is 1% to 20%. However, the photopolymerizable composition that can be used in the present invention is not limited to these, and can be appropriately selected from known ones.

In the present invention, the photopolymerizable light-shielding material layer is formed on an aggregate of pixels, which is usually composed of a large number of R, G, and B pixels, on a glass plate. A method of applying and drying a solution of the product using a coater such as a spin coater or a roll coater, a method of screen printing, or a photopolymerizable light-shielding material formed by applying and drying on another temporary support using a laminator It can be formed by a known method such as a transfer / lamination method. Further, an oxygen-blocking thin film soluble in a developer or water, such as polyvinyl alcohol, may be formed on the photopolymerizable light-shielding material layer. Among these, a method of stacking by transfer, which is simple in process and provides stable performance, is preferred. In this case, an intermediate layer having good releasability from the temporary support can be provided between the light-shielding material layer and the temporary support. This intermediate layer is preferably made of a material having a small oxygen permeability so as to increase the photopolymerizability of the light shielding material layer. Further, in order to prevent transfer failure due to foreign matter during transfer, it is preferable to provide a layer made of a flexible material and having a cushioning effect between the light-shielding material layer and the temporary support. This aspect is described in Japanese Patent Application No. 4-12980.

In the method of the present invention, the developer is preferably an aqueous alkali solution or a solution in which an organic solvent miscible with water is added together with an alkaline substance. Suitable alkaline substances include alkali metal hydroxides (eg, sodium hydroxide,
Potassium hydroxide), alkali metal carbonates (eg, sodium carbonate, potassium carbonate), alkali metal bicarbonates (sodium hydrogen carbonate, potassium hydrogen carbonate), alkali metal silicates (sodium silicate, potassium silicate)
Alkali metal metasilicates (sodium metasilicate,
Potassium metasilicate), triethanolamine, diethanolamine, monoethanolamine, morpholine, tetraalkylammonium hydroxides (eg, tetramethylammonium hydroxide) or trisodium phosphate. Suitable water-miscible organic solvents include methanol, ethanol, 2-propanol, 1-propanol, butanol, diacetone alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono n-butyl ether, benzyl alcohol, Acetone, methyl ethyl ketone, cyclohexanone, ε-caprolactone, γ-
Butyrolactone, dimethylformamide, dimethylacetamide, hexamethylphosphoramide, ethyl lactate,
Methyl lactate, ε-caprolactam, N-methylpyrrolidone. A known surfactant can be added to the developer. The developer can be used as a bath solution or a spray solution. To remove the uncured portion of the photopolymerizable light-shielding material layer, a method such as rubbing with a rotating brush or a wet sponge in a developer can be combined. The temperature of the developer is usually preferably around room temperature to 40 ° C. A water washing step can be added after the development processing.

The method of removing the overlapping portion of the light-shielding pattern with the R, G, and B pixels of the present invention may be performed simultaneously with the above-described developing step or as a step after the developing step. As described above, in the side etching, the overlapping portion of the pattern-exposed photopolymerizable light-shielding material layer and the pixel of the other color, in the vicinity of the portion where the light-shielding material and the pixel are in contact, is not sufficiently cured. It is to dissolve and remove the overlapped portion by utilizing this fact. Therefore, the chemical used in the side etching step may be basically the same as the above-mentioned developer, but it is preferable to use a liquid having a slightly lower dissolving power. The dissolving power can be adjusted by adjusting the concentration of the alkaline substance, the concentration of the water-miscible organic solvent, and the concentration of the surfactant. Also, the method of side etching is the same as that described in the development process, and a chemical solution may be immersed as a bath solution in the substrate to be side-etched or applied in a spray form, and further rubbed with a rotating brush or a wet sponge. This can be carried out advantageously. By this processing, a multicolor pattern having excellent flatness including a light-shielding pattern can be obtained.

After the above process, the entire surface is exposed through the substrate to sufficiently polymerize and cure the light-shielding pattern. The exposure amount in this case is within a range where the light-shielding pattern is sufficiently cured,
It can be selected as appropriate. For efficient polymerization,
It is preferable to perform not only exposure through the substrate but also exposure from the surface. The light source, atmosphere, and the like are as described above.

Thereafter, by performing a heat treatment, the light shielding pattern can be more completely cured. Processing temperature is about 130-300 ° C, preferably about 200-250 ° C
It is.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

[0020]

【Example】

Example 1 A coating solution having the following formulation H1 was applied on a polyethylene terephthalate film temporary support having a thickness of 100 μm.
After drying, a thermoplastic resin layer having a dry film thickness of 20 μm was provided.

Thermoplastic Resin Layer Formulation H1: Vinyl chloride / vinyl acetate copolymer (weight ratio: PVC / vinyl acetate = 75/25, degree of polymerization: about 400, MPR-TSL manufactured by Nissin Chemical Co., Ltd.) 290. 0 g vinyl chloride-vinyl acetate-maleic acid copolymer (weight ratio: vinyl chloride / vinyl acetate / maleic acid = 86/13/1, degree of polymerization: about 400, MPR-TM 76.0 g manufactured by Nissin Chemical Co., Ltd. Dibutyl acid 88.5 g Fluorinated surfactant (F-177P manufactured by Dainippon Ink and Chemicals, Inc.) 5.4 g MEK 975.0 g

Next, the following formulation B1 was placed on the thermoplastic resin layer.
And dried to a dry film thickness of 1.6 μm.
An m-thick separation layer was provided. Separation layer formulation B1: polyvinyl alcohol (PVA205 manufactured by Kuraray Co., Ltd., saponification ratio = 80%) 173.2 g fluorinated surfactant 8 g distilled water 2800 g

4 having the above-mentioned thermoplastic resin layer and separation layer
Photosensitivity of four colors of black (for the B1 layer), red (for the R layer), green (for the G layer) and blue (for the B layer), each having the formulation shown in Table 1, on one temporary support Apply and dry the solution,
A colored photosensitive resin layer having a dry film thickness of 2 μm was formed.

[0024]

[Table 1]

Further, a cover sheet of polypropylene (thickness: 12 μm) was pressed on the photosensitive resin layer to prepare red, blue, green and black photosensitive transfer materials. Using this photosensitive transfer material, a color filter was prepared by the following method. The covering sheet of the red photosensitive transfer material is peeled off, and the photosensitive resin layer surface is transparent glass substrate (1.1 m thick).
m) to a laminator (VP-I manufactured by Taisei Laminator Co., Ltd.)
I) using pressure (0.8 kg / cm ² ), heating (13
(0 ° C.) and bonded, and subsequently peeled off at the interface between the separation layer and the thermoplastic resin layer, thereby simultaneously removing the temporary support and the thermoplastic resin layer. Next, it is exposed through a predetermined photomask,
Unnecessary portions were removed by development to form a red pixel pattern on the glass substrate. Next, a green photosensitive transfer material was adhered to the glass substrate on which the red pixel pattern was formed in the same manner as described above, and peeling, exposing, and developing were performed to form a green pixel pattern. The same process was repeated with a blue photosensitive transfer material to form R, G, and B patterns on a transparent glass substrate. Further, a black photosensitive resin layer was provided on the entire surface by the transfer method using the above black photosensitive transfer material. The transfer was performed at a temperature of 130 ° C. and a pressure of 0.8 kg / cm.
^{2. The} transfer speed was 0.2 m / min. When forming a pattern, development is performed in a 1% aqueous solution of sodium carbonate at 33 ° C. for 30 minutes.
This was performed by immersion for 2 seconds. Next, the entire surface was exposed from the back side, and subsequently, the exposure was performed from the front side through a photomask in which the periphery of the R, G, and B pixels and the pixels of the black matrix overlap by 5 μm each. Next, development was performed by spraying a predetermined developing solution to obtain a color filter having an overlapping pattern.

Thereafter, side etching was performed by rubbing with a sponge made of PVA for 75 seconds in the same developer to obtain a color filter having no pixel overlap and having no pinhole. Then, through the substrate, 1000mJ /
Exposure to the entire surface of cm ² was performed. Next, when post-baking was performed in an oven at 220 ° C. for 1 hour, a color filter having no wrinkles and having a black matrix with high light-shielding ability (optical density 3.2) was obtained.

Comparative Example 1 A light-shielding pattern was formed in the same manner as in Example 1 except that no light was exposed through the substrate. In this case, wrinkles occurred in the black matrix after the post-cure, resulting in unevenness.

[0028]

According to the present invention, it is possible to produce a color filter having no pixel overlap, no pinhole, sufficient light-shielding ability, and a uniform light-shielding pattern by a simple method. is there.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G02F 1/1335 505 G02B 5/20 101

Claims (3)

(57) [Claims] 1. A method for forming a light-shielding pattern, wherein the following steps are performed in the following order. Forming a pixel pattern of single or multiple colors on a substrate; forming a photopolymerizable light-shielding material layer on a substrate having the pixel pattern of single or multiple colors; Exposing at least a portion of the pixel pattern where no pixels are present to the photopolymerizable light-shielding material through a light-transmitting mask; developing the photopolymerizable light-shielding material to remove unexposed portions; A step of side-etching each pixel of the light-shielding pattern after or at the same time as forming to remove an overlapping portion of the colored pattern and the light-shielding pattern, and a step of exposing the entire surface at least from the back surface of the substrate. 2. The method for forming a light-shielding pattern according to claim 1, further comprising a step of performing a heat treatment after all the steps and curing the light-shielding pattern. 3. The method for forming a light-shielding pattern according to claim 1, wherein the photopolymerizable light-shielding material is formed by a layer transfer method.