JP2000162426A - Color filter, manufacture thereof, and liquid crystal element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent ink color mixture between the adjacent opening parts and to effectively store ink in each opening part for forming a uniform colored part so as to prevent a defect or unevenness by increasing the surface energy on the opening part side face in a light shield layer. SOLUTION: Using a black resin composition, a light shield layer 2 having an opening part is formed on a transparent base board 1. Photocatalytic particles are added to the light shielding layer 2. Using a diffusing plate 3, an UV ray is radiated from the back face of the base board 1 under an ozone atmosphere. When the photocatalytic particles in the light shielding layer 2 are optically excited, the side face of the light shield layer 2 absorbs water molecules in the air so as to be provided with a hydrophilic characteristic. In this way, the surface energy of the upper face in the light shield layer 2 exceeds that of the side face. In this case, a contact angle of the light shield layer 2 with water is 60 deg. or more on the upper face, while it is approximately 20-30 deg. on the side face. To the opening part in the light shield layer 2, red ink, green ink, or blue ink 4 is applied and hardened so as to form a colored part 5, and if necessary, a protective layer 6 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a color filter constituting a liquid crystal element for color display used for a display of a color television or a personal computer, etc. The present invention relates to a liquid crystal element formed using a color filter.

[0002]

2. Description of the Related Art In recent years, the development of personal computers,
In particular, with the development of portable personal computers, acceptance of liquid crystal displays, especially color liquid crystal displays, has been increasing. However, significant cost reduction is required for further widespread use, and in particular, cost reduction of a color filter having a high specific gravity is required.

As a method of manufacturing a color filter at low cost, a light-shielding black matrix is formed on a glass substrate, ink is ejected to an opening of the black matrix using an ink jet recording apparatus, and the ink is cured. There has been proposed a method of forming a colored portion by using the method. In this manufacturing method, in order to make the ink fit in the opening of the black matrix favorably, a material that is hardly wetted by the ink and easily repells the ink is studied as a material of the black matrix.

For example, Japanese Patent Application Laid-Open No. 7-35917 proposes a method of forming a black matrix using a material having a contact angle of 20 ° or more with ink. Japanese Patent Application Laid-Open No. 7-35915 proposes a material having a contact angle of 40 ° or more with water as a black matrix material. Further, Japanese Unexamined Patent Publication No.
No. 47637 discloses that the critical surface tension of each material is defined as substrate surface>ink> black matrix surface,
Black matrix surface <35 dyne / cm, substrate surface ≧ 35 dyne / cm, ink 5 dyne from both
/ Cm has been proposed to have a difference of not less than / cm. In these proposals, it is proposed that a material of the black matrix contains a fluorine compound or a silicon compound in order to impart water repellency.

Japanese Patent Application Laid-Open No. HEI 4-121702 proposes a method in which a bank having an affinity for a substrate opposite to that of a substrate is formed, and ink is injected into the gap between the banks. Absent.

[0006]

However, when a fluorine compound or a silicon compound as a water repellent is mixed with the material of the black matrix as described above, post-baking, which is the final step for forming a black matrix pattern, is performed. At this time, the water repellent in the black matrix material is volatilized and thinly adheres to the surface of the glass substrate exposed at the opening of the black matrix. Therefore, the glass substrate surface becomes water-repellent, and there is a problem that the ink does not adhere well to the glass substrate surface when the ink is applied to the opening.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a color filter in which a colored portion is formed by applying ink to an opening of a black matrix. Is to produce a high-contrast color filter free of defects such as ink repellency, containing ink effectively, forming a uniform colored portion, and having no defects or unevenness. To provide a liquid crystal element having excellent color display characteristics at a low cost.

[0008]

A first aspect of the present invention is a step of forming a light-shielding layer having an opening on a transparent substrate using a black resin composition, and increasing the surface energy of the side surface of the opening of the light-shielding layer. A method of manufacturing a color filter, comprising: performing a treatment; and applying ink to the opening of the light-shielding layer, and curing the ink to form a colored portion.

In the manufacture of a color filter, the black matrix must be formed of a material which is hardly wetted by the ink, that is, the black matrix must be formed of a material which is hardly wetted by the ink so that the ink does not cross the black matrix pattern and mix with the ink applied to the adjacent opening. It is necessary that the surface energy of the matrix is smaller than the surface energy of the ink. Furthermore, in order to effectively store the ink in the opening of the black matrix, the surface energy of the side surface of the opening of the black matrix needs to be larger than that of the upper surface of the black matrix. On the other hand, in order for the ink to spread sufficiently in the opening of the black matrix and to form a color filter with good contrast, the surface of the transparent substrate exposed to the opening must be sufficiently wet with the ink, that is, the surface energy of the transparent substrate. Is required to be larger than the surface energy of the ink. In summary, the ideal surface energy state is: black matrix upper surface <black matrix opening side surface <ink <transparent substrate.

In the present invention, the above-described ideal surface energy state is formed by selectively increasing the surface energy of the side surface of the opening of the black matrix, whereby the ink is repelled well on the upper surface of the black matrix. On the side surface, it is possible to enhance the wettability of the ink and to spread the ink well in the opening to form a uniform colored portion.

A second aspect of the present invention is a color filter comprising a transparent substrate, a light-shielding layer having an opening on the transparent substrate, and a colored portion formed in the opening of the light-shielding layer, A color filter manufactured by the method for manufacturing a color filter of the present invention.

A third aspect of the present invention is a liquid crystal element characterized in that liquid crystal is sandwiched between a pair of substrates, and one of the substrates is formed using the color filter of the present invention.

[0013]

FIG. 1 is a process chart of a preferred embodiment of a method for manufacturing a color filter according to the present invention. (A) to (e) in the figure are schematic cross-sectional views respectively corresponding to the following steps (a) to (e). Hereinafter, each step will be described.

Step (a) A light shielding layer 2 having an opening is formed on a transparent substrate 1 using a black resin composition. This light shielding layer 2 is usually called a black matrix or a black stripe.
As the transparent substrate 1 used in the present invention, a glass substrate is usually used, but a plastic substrate or the like may be used as long as necessary characteristics such as transparency and mechanical strength as a color filter are satisfied. Further, a thin film for improving the adhesion to the ink may be formed on the surface.

In the present invention, the black resin composition forming the light shielding layer 2 may be either photosensitive or non-photosensitive. As the photosensitive black resin composition, a normal positive type photoresist is mixed with a black pigment or dye, and if it does not interfere with the subsequent steps and reliability, the surface activity is optionally determined. Additives such as agents may be added. When the composition is applied to a transparent substrate, it is dispersed in an appropriate solvent.

As the above-mentioned black pigment, carbon black, a black organic pigment or the like is used.

The positive photoresist can be appropriately selected from UV resist, DEEP-UV resist and the like. As the UV resist, specifically, a novolak resin-diazonaphthoquinone-based resist is preferably used. DEEP-UV resists include, for example, polymethyl methacrylate, polystyrene sulfone, polyhexafluorobutyl methacrylate, polymethyl isopropenyl ketone, and brominated poly 1
Radiation-decomposable polymer resists such as trimethylsilylpropyne; and dissolution inhibitor-based positive resists such as o-nitrobenzyl cholic acid.

When the above-described photosensitive black resin composition is used, the resin composition is applied to the transparent substrate 1 using a spin coater, a die coater, a dip coater, or the like so as to have a required thickness. I do. In the present invention, the thickness of the light shielding layer 2 is preferably about 1 μm. The resin composition layer formed by application is prebaked using a hot plate or the like, and temporarily cured, and is exposed using an exposure machine having a wavelength matching the sensitivity of the material and a mask having a predetermined pattern. After exposure, development, and rinsing, post-baking is performed to fully cure.

The non-photosensitive black resin composition capable of forming the light-shielding layer 2 includes, for example, resin components such as polyimide, acrylic acid monomer, and urethane acrylate, and the same black pigment as the above-mentioned photosensitive resin composition. A dye or dye containing various additives as necessary is dissolved or dispersed in an appropriate solvent before use. When using such a non-photosensitive resin composition, after forming a coating film by applying the non-photosensitive resin composition on a transparent substrate in the same manner as when using the above-described photosensitive resin composition, The coating can be etched using a photoresist as a mask to form a pattern. Alternatively, a pattern may be formed by lift-off using a photoresist.

Step (b) A process for selectively increasing the surface energy of the side surface of the opening of the light shielding layer 2 is performed. Specifically, the difference between the contact angle with water on the upper surface and the side surface of the light shielding layer 2 is 15 ° or more, preferably 4 °.
A process is performed so as to be 0 ° or more. As such a treatment, for example, UV ozone treatment of irradiating ultraviolet rays (UV light) in an ozone atmosphere is preferably used. In this case, as shown in FIG. UV light is irradiated from below on the back surface of the transparent substrate 1.

In addition, by adding photocatalyst particles to the light-shielding layer 2 in order to effectively increase the surface energy, photoexcitation of the particles can be utilized. When the light-shielding layer to which the photocatalyst particles are added is irradiated with light having an energy higher than the band gap energy of the photocatalyst particles, hydroxyl groups are chemically adsorbed on the surface of the photocatalyst particles by the photocatalytic effect, and water molecules in the air are physically adsorbed to the hydroxyl groups. Therefore, hydrophilicity is developed in the light-irradiated area of the light-shielding layer. Such photocatalytic particles include, for example,
Anadase-type titanium oxide, rutile-type titanium oxide, zinc oxide, strontium titanate, tin oxide, bismuth trioxide, and the like.

The average particle size of the photocatalyst particles is preferably 0.01 μm or less, and the amount added to the resin composition is preferably 20 parts by weight per 100 parts by weight of the resin solids.
0 parts by weight (200 phr) or less. As a means for excitation, UV light having a wavelength of 413 nm or less may be used.

When the light-shielding layer 2 containing the photocatalyst particles as described above is irradiated with UV light from the back surface of the transparent substrate 1 through the diffusion plate 3, the side surface and the lower surface of the light-shielding layer 2 (adhesion surface with the transparent substrate 1) The photocatalyst particles are photoexcited, and the side surface is in contact with air, so that water molecules in the air are adsorbed and hydrophilic, but the lower surface is not in contact with air and thus is not hydrophilized. Thereby, the surface energy of the light-shielding layer 2 is optimized such that the upper surface is smaller than the side surface. At this time, the contact angle of the light-shielding layer 2 with water is 60 ° or more on the upper surface and about 20 to 30 ° on the side surface, depending on the material and process conditions.

On the other hand, since the surface energy of the transparent substrate 1 is generally 60 dyne / cm or more in the case of glass, the surface energy state after this step can be determined by appropriately selecting the ink so that the upper surface of the light-shielding layer is smaller than the light-shielding layer. Layer side <ink <
An ideal system called a transparent substrate is realized.

Step (c) R (red), G (green), and B (blue) inks 4 are applied to the openings of the light shielding layer 2. As a method of applying ink, a general printing method such as offset printing, gravure printing, or screen printing can be used.However, according to a printing method using an inkjet recording apparatus, since a plate is not used, the ink liquid is not used. Manipulating the droplets is preferable in that high-precision patterning becomes possible. The ink used here is the light shielding layer 2
A material which is easy to be repelled on the upper surface and easily wetted on the side surface of the opening and the surface of the transparent substrate 1 is appropriately selected and used. The surface energy (surface tension) is usually 30 to 70 dyne / c.
m.

As such an ink, an ink composed of a resin composition which is cured by applying energy and containing a coloring material is preferably used. As the coloring material, a general dye or pigment can be used.
Anthraquinone dyes, azo dyes, triphenylmethane dyes, polymethine dyes and the like can be used.

As the resin used for the ink, a resin which is cured by energy application such as heat treatment or light irradiation is used. Specifically, a combination of a known resin and a crosslinking agent can be used as the thermosetting resin. For example, acrylic resin, melamine resin, hydroxyl or carboxyl group-containing polymer and melamine, hydroxyl or carboxyl group-containing polymer and polyfunctional epoxy compound, hydroxyl or carboxyl group-containing polymer and cellulose reaction type compound, epoxy resin and resol type resin, epoxy Examples include resins and amines, epoxy resins and carboxylic acids or acid anhydrides, and epoxy compounds. As the photocurable resin, a known resin, for example, a commercially available negative resist is preferably used.

Various solvents can be added to the ink. In particular, a mixed solvent of water and a water-soluble organic solvent is preferably used from the viewpoint of dischargeability in an inkjet method.

Further, in addition to the above-mentioned components, a surfactant, an antifoaming agent, a preservative, and the like can be added in order to give desired characteristics as required. Can be added.

Further, among the above-mentioned light or thermosetting resins, those which do not dissolve in water or a water-soluble organic solvent can be used as long as they can be stably ejected. I do not care. In particular, when a monomer that polymerizes by light is used, a solventless type in which a dye is dissolved in the monomer may be used.

Further, as the ink jet recording apparatus, a bubble jet type using an electrothermal converter or a piezo jet type using a piezoelectric element can be used as an energy generating element, and the coloring area and the coloring pattern can be arbitrarily set. Can be set.

Step (d) If necessary, a treatment such as drying and heat curing is performed, and the ink 4 is cured to form the colored portion 5.

Step (e) If necessary, a protective layer 6 is formed. As the protective layer 6,
A photo-curing type, thermo-setting type or photo-heating type resin layer, an inorganic film formed by vapor deposition, sputtering or the like can be used. Any material that can withstand the alignment film forming process or the like can be used.

Next, a liquid crystal device using the color filter of the present invention will be described. FIG. 2 is a schematic cross-sectional view of an embodiment of an active matrix type liquid crystal element incorporating the color filter formed in the step of FIG. In FIG. 2, 12 is a common electrode, 13 is an alignment film, 20 is a substrate,
22 is a pixel electrode, 23 is an alignment film, 14 is a liquid crystal compound, 1
Reference numeral 5 denotes backlight, and 16 denotes emission light, and the same members as those in FIG. 1 are denoted by the same reference numerals.

A liquid crystal element for color display is generally formed by fitting a color filter side substrate (1) and a TFT substrate (20) and enclosing a liquid crystal compound 14. A TFT (not shown) is provided inside one substrate of the liquid crystal element.
And transparent pixel electrodes 22 are formed in a matrix. A color filter layer is provided inside the other substrate 1 so that the R, G, and B colored portions 5 are arranged at positions facing the pixel electrodes 22, and a transparent common electrode 1 is placed thereon.
2 are formed on one side. Further, alignment films 13 and 23 are formed in the planes of both substrates, and by subjecting them to rubbing treatment, liquid crystal molecules can be aligned in a certain direction.

A polarizing plate (not shown) is adhered to the outside of each of the substrates 1 and 20, and a combination of a fluorescent lamp (not shown) and a scattering plate (not shown) is generally used as a backlight to back up the liquid crystal compound. Display is performed by functioning as an optical shutter that changes the transmittance of the light beam 15.

The liquid crystal element is of a transmissive type. However, by using a reflective material for the pixel electrode 22 and the substrate 20 or by providing a separate reflective layer on the substrate 20 side, a reflective type liquid crystal element is provided. It is also possible to construct the polarizing plate, in which case the polarizing plate is used only on the observer side.

The liquid crystal device of the present invention may be configured using the color filter of the present invention, and the other components may be formed by applying the conventional liquid crystal device technology such as the material and manufacturing method. It is possible.

[0039]

EXAMPLES Example 1 A glass substrate was subjected to alkaline ultrasonic cleaning using a 2% aqueous sodium hydroxide solution,
Black photosensitive resin composition obtained by mixing carbon black ("MA-100" manufactured by Mitsubishi Kasei Co., Ltd.) with a positive photoresist material ("PMER-P" manufactured by Tokyo Ohka Kogyo Co., Ltd.) after V ozone treatment Was applied by a spin coater so that the film thickness became 1 μm. Place this substrate in a clean oven
Heat treatment was performed at 0 ° C. for 10 minutes to temporarily cure the resist.

Using a UV exposure apparatus, proximity exposure is performed using a predetermined pattern mask, and subsequently, a developer of an aqueous inorganic alkali solution (PMER, manufactured by Tokyo Ohka Kogyo Co., Ltd.)
After immersion rocking in a developing solution "P-IS"), a rinsing process with pure water was performed to completely remove the developing solution, and then a heating process was performed at 150 ° C. for 30 minutes in a clean oven. A black matrix having a predetermined pattern shape was obtained.

Then, UV light (mercury xenon lamp, center wavelength: 300 nm, illuminance: 10 mW / c) in an ozone atmosphere
m ² ) was irradiated from the back surface of the glass substrate (the side on which the black matrix was not provided) through a diffusion plate.

Next, using an ink jet recording apparatus,
R, G, and B dye-based inks were discharged into the openings of the black matrix. The ink contains a dye (C.I.
Acid red 118, C.I. I. Acid Green 2
5, C.I. I. Acid Blue 113) is dispersed in a resin (a self-crosslinking thermosetting resin mainly composed of an acrylic-silicone graft polymer), and a solvent (isopropanol,
Diethylene glycol, polyethyleneimine, N-methyl-2-pyrrolidone, and cyclohexanone were appropriately selected and used depending on the color of the ink. ) Is added with a surface tension modifier (acetylenol)
The surface energy was 32 dyne / cm.

The above-mentioned ink uniformly covered the surface of the glass substrate exposed at the opening of the black matrix, and found no defects such as bleeding or protrusion, color mixing with the ink at the adjacent opening, and white spots. . afterwards,
After performing a heat treatment at 200 ° C. for 60 minutes to cure the ink and form a colored portion, the protective layer is applied and formed, and even if a transparent conductive film is formed, the colored portion has excellent adhesion, No problems occurred. When a liquid crystal element was assembled by a conventional method using the color filters thus obtained, a liquid crystal element with no defect and excellent color characteristics was obtained.

Example 2 A glass substrate was prepared in the same manner as in Example 1 except that the photosensitive black resin composition used in Example 1 was mixed with 200 phr of titanium oxide particles having an average particle size of 0.01 μm. A black matrix is formed, and the entire surface is irradiated with UV light (center wavelength: 365 nm, illuminance: 20 mW / cm ² ) from the back surface of the substrate via a diffusion plate to photo-excit titanium oxide particles contained in the black matrix, thereby forming a side surface of the opening. Increased surface energy.

The same ink as in Example 1 was discharged to the opening of the black matrix by using an ink jet recording apparatus.

The ink uniformly covered the surface of the glass substrate exposed at the opening of the black matrix, and did not find any defect such as bleeding or protrusion, color mixing with the ink of the adjacent opening, and white spots. . afterwards,
After performing a heat treatment at 200 ° C. for 60 minutes to cure the ink and form a colored portion, the protective layer is applied and formed, and even if a transparent conductive film is formed, the colored portion has excellent adhesion, No problems occurred. When a liquid crystal element was assembled by a conventional method using the color filters thus obtained, a liquid crystal element with no defect and excellent color characteristics was obtained.

Example 3 On the same glass substrate as in Example 1, polyimide (solvent: N-methyl-2-pyrrolidone)
A resin composition obtained by mixing the carbon black used in Example 1 and the titanium oxide particles used in Example 2 was applied by a spin coater so as to have a thickness of 1 μm, and then a clean oven at 130 ° C. for 30 minutes. Was performed.

On the black resin composition layer, a positive photoresist ("Microposi" manufactured by Shipley) was used.
“tRC100 30CP” was applied by a spin coater, and heat-treated at 80 ° C. for 10 minutes in a clean oven. Next, after performing proximity exposure using a predetermined pattern mask using an exposure apparatus, a developer (S
"Micropost Level" manufactured by Hipley
and the black resin composition layer was developed at the same time. Next, the resist was removed by methyl cellosolve acetate, and a heat treatment was further performed at 150 ° C. for 30 minutes to obtain a black matrix having a predetermined pattern shape.

Thereafter, in the same manner as in Example 2, UV light was irradiated from the back surface of the glass substrate to photo-excite the titanium oxide particles, thereby increasing the surface energy on the side surface of the opening of the black matrix.

R, G, and B pigment-based inks were discharged into the openings of the black matrix using an ink jet recording apparatus. The above-mentioned ink was prepared using pigments (CI Pigment Red 177, CI Pigment Green 36,
C. I. Pigment Blue 209) with a resin (acryl-
It was dispersed in a self-crosslinking thermosetting resin containing a silicone graft polymer as a main component, and a solvent (isopropanol, diethylene glycol, polyethyleneimine, N-methyl-2-pyrrolidone, or cyclohexanone was appropriately selected and used depending on the color of the ink.) And a surface tension regulator (acetylenol) was added thereto, and the surface energy was 48 dyne / cm.

The ink uniformly covered the surface of the glass substrate exposed at the opening of the black matrix, and did not find any defect such as bleeding or protrusion, color mixing with the ink of the adjacent opening, and white spots. . afterwards,
After performing a heat treatment at 200 ° C. for 60 minutes to cure the ink and form a colored portion, the protective layer is applied and formed, and even if a transparent conductive film is formed, the colored portion has excellent adhesion, No problems occurred.

Comparative Example 1 A negative resist ink ("CFP" manufactured by Tokyo Ohka Kogyo Co., Ltd.) was formed on the same glass substrate as in Example 1.
R BK416 ”) to which a fluorine-based surfactant (“ Fluorad FC-430 ”manufactured by Sumitomo 3M) is added as a water repellent, using a spin coater so that the film thickness becomes 1 μm, and then applied at 120 ° C. for 3 minutes. After prebaking, exposure was performed using a mask having a predetermined pattern, development (using a sodium carbonate solution), rinsing with pure water, and heat curing at 220 ° C. for 60 minutes to form a black matrix pattern.

Next, the pigment-based ink used in Example 3 was discharged into the opening of the black matrix and cured using an ink jet recording apparatus.

When the obtained color filter was observed under a microscope, the difference in surface energy between the black matrix and the surface of the glass substrate could be increased by adding a water repellent to the black matrix. Perhaps because there was no difference in surface energy at the side surface of the opening, the degree of ink being drawn into the opening was weak, and color mixing was observed between the adjacent colored portions.

[0055]

According to the present invention, since there is no repelling of the ink in the opening of the black matrix, a uniform colored portion can be formed in the opening, and white spots, uneven color, mixed color, etc. can be formed. A color filter with no defects and high contrast can be formed with high yield. as a result,
Using the color filter, a liquid crystal element having excellent color display characteristics can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a process chart of one embodiment of a method for manufacturing a color filter of the present invention.

FIG. 2 is a schematic sectional view of one embodiment of the liquid crystal element of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Light-shielding layer 3 Diffusion plate 4 Ink 5 Coloring part 6 Protective layer 12 Common electrode 13 Alignment film 14 Liquid crystal compound 15 Backlight 16 Emission light 20 Substrate 22 Pixel electrode 23 Alignment film

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Nagato Osano 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H048 BA00 BA64 BB02 BB14 BB23 BB37 BB44 2H091 FA34Y FB12 FB13 FC10 FC22 FC23 FC25 FC29 FD24 LA15

Claims (6)

[Claims] 1. A step of forming a light-shielding layer having an opening on a transparent substrate using a black resin composition, a step of increasing the surface energy of the side surface of the opening of the light-shielding layer, and a step of opening the light-shielding layer. Applying an ink to the portion and curing the ink to form a colored portion. 2. The method for manufacturing a color filter according to claim 1, wherein the process of increasing the surface energy of the side surface of the opening of the light-shielding layer is a process of irradiating ultraviolet rays from the back surface of the transparent substrate through a diffusion plate in an ozone atmosphere. 3. The method for producing a color filter according to claim 1, wherein the light-shielding layer contains photocatalyst particles in advance. 4. The method for producing a color filter according to claim 1, wherein the means for applying ink to the opening of the light-shielding layer is an ink-jet method. 5. A color filter comprising: a transparent substrate; a light shielding layer having an opening on the transparent substrate; and a colored portion formed in the opening of the light shielding layer. A color filter manufactured by any one of the color filter manufacturing methods described above. 6. A liquid crystal device comprising a pair of substrates sandwiching liquid crystal, and one of the substrates is formed using the color filter according to claim 5. Description: