JPH04358124A - Color filter substrate and pattern forming method - Google Patents

Abstract

PURPOSE:To simplify stages and, to reduce costs by using a visible light transparent resin which is sensitive only to respective wavelengths of blue, green and red and is not sensitive to other spectra. CONSTITUTION:Color patterns of color filters for a liquid crystal are exposed to a film coated with microcapsules contg. both of a curable base material to be cured by respective light rays of blue, green and red and dye precursors of complementary colors to become dyes corresponding to the light rays by reacting with an acid. This film with the microcapsule side as a transparent substrate is brought into pressurized contact with a glass plate provided with a layer of a compd. which is intrinsically an acid to develop and transfer this compd. to the transparent substrate. The above-mentioned curable base material is formed of a free radical polymerizable monofunctional and multifunctional ethylenic unsatd. org. compd. contg. a photopolymn. initiator, the oligomer or prepolymer of the compds. or a mixture composed thereof. The dye precursors contain a photosensitizer, cyan leuco dye which reacts with red light, a magenta leuco dye which reacts with green eye and a yellow leuco dye which reacts with blue light.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel color filter substrate for liquid crystal images and a method for forming a color pattern thereon. In particular, after exposing a photosensitive film coated with microcapsules containing a dye precursor, development and transfer are performed in one step on a transparent substrate, which has succeeded in greatly simplifying the color filter manufacturing process. .

0002

[Prior Art] Liquid crystal displays have become widespread in a wide range of areas.
Although the scope of its application is expanding more and more, the mere TN type black and white display is not enough, and the display function is insufficient, so there is a demand for color display products, character display, analog display, graphic display, TV display. Color LCD displays are making inroads into a variety of new fields.

[0003] The main types of color display on liquid crystals include the birefringence control method, the pleochroic method, the twisted nematic method, and the cholesteric method, but in all cases, color filters are an important part of the display. It is one of the elements. In particular, it is no exaggeration to say that the quality of the colors is determined by the performance of the color filter.

Various methods have been tried to produce this color filter, including dyeing, printing, and electrodeposition pigment dispersion, but the most popular method is dyeing using a dyeable photopolymer. This method is further classified into protective film method, window opening method, adhesion method, etc.

However, in the protective film method, each step of applying a photosensitive agent, exposing, developing, dyeing, and forming a resisting layer must be performed for each of the red, green, and blue patterns, making the process particularly long and expensive. become. The window opening method cannot create black stripes, and even with the fixing method, which is simple and widely used, it is necessary to repeat the dyeing, fixing, and resist dyeing processes for each color, which makes the process long. The need for cost reduction is increasing.

On the other hand, various photosensitive resins that are polymerized by light have been developed, but the curable base materials that are cured are mainly acrylic monomers or oligomers. However, photopolymerization initiators are sensitive to ultraviolet rays or short wavelengths of visible light, ranging from violet to blue.There are no photopolymerization initiators that are sensitive to all visible light, especially long wavelengths of visible light; was also relatively narrow. Recently, materials sensitive to visible light across the entire visible spectrum (around 400 to 700 μm) have been developed, and photoinitiators have been proposed that are sensitive only to the blue, green, and red spectra, respectively, and not to other spectra. ing.

The present invention attempts to utilize such a selective visible light photosensitive resin for manufacturing a color filter substrate.

[0008]

[Problems to be Solved by the Invention] The present invention solves problems in the production of conventional color filters, such as the complicated and long process, resulting in low yield, high cost, and low precision. purpose.

[0009]

[Means for solving the problems] The present invention solves the above problems,
A curable substrate that is cured by blue, green, and red light on a transparent substrate and non-stretchable film with a layer containing a compound that is acidic in nature, and a complementary color that reacts with the acid and corresponds to each light. We have developed a color filter substrate for liquid crystal images, which consists of a photosensitive film coated with microcapsules made of a dye precursor that becomes a pigment. This problem was solved by a method for forming a color pattern of a color filter for a liquid crystal image, which is characterized by pressing together with the acid compound-containing side of a transparent substrate, and developing and transferring the pattern to the transparent substrate.

[0010] The acid compound in the present invention is preferably an organic compound such as a phenol derivative or an aromatic carboxylic acid.

[0011] Although a glass plate is most commonly used as a transparent substrate, a relatively heat-resistant transparent polymer can also be used depending on the purpose. In order to apply an acid compound to this transparent substrate, the compound may be dissolved in an organic solvent or the like, applied by a method such as spin coating, and dried. Alternatively, a method such as vacuum deposition may be used, and it is necessary to apply it as thinly as possible to maintain transparency and uniformity.

As the non-stretchable film serving as the base material of the photosensitive film, a fully biaxially stretched synthetic resin film such as Mylar, polyester, or nylon is preferred.

The curable base material consists of an organic compound having one or more free radical polymerizable ethylenically unsaturated groups in its molecule, an oligomer or prepolymer of the compound, or a mixture thereof, and a photopolymerization initiator. It is something.

Examples of compounds having one ethylenically unsaturated group in the molecule include alkyl esters of acrylic acid and methacrylic acid having 1 to 18 carbon atoms, styrene, substituted styrenes, vinyl acetate, vinyl ethers, allyl ethers, and allyl esters. etc. can be mentioned.

Compounds having a plurality of ethylenically unsaturated groups include trimethylolpropane, pentaerythritol, dipentaerythritol, ethylene glycol, diethylene glycol, propylene glycol,
glycerin, sorbitol, neopentyl glycol,
Mention may be made of polyacrylates or polymethacrylates with polyhydric alcohols such as 1,6-hexanediol, hydroxy-terminated polyesters, hydroxy-terminated epoxy resins, hydroxy-terminated polyurethanes or polyphenols such as bisphenol A. can.

As photopolymerization initiators, blue (42
0 to 440 μm), green (480 to 550 μm)
The radical initiator may be of any type as long as it is selectively sensitive to red (near 570 to 650 μm) light; for example, a cationic dye-borate anion complex may be used.

This is used as a microcapsule together with a curable base material, a dye precursor, an autooxidizing agent, a solvent for an image forming agent, a wall molding material, etc. As a dye precursor, cyan leuco dye, cyan leuco dye, Contains magenta leuco dye and yellow leuco dye.

In this case, the cationic dye includes a cyanine dye, a dye in which a cationic moiety such as a quaternary ammonium ion is covalently bonded to another neutral dye structure via a bonding group. The borate anion is a borate anion bonded to four alkyl, aryl, alkaryl, aralkyl, alkenyl, alkynyl, alicyclic, saturated or unsaturated heterocyclic groups or mixed groups thereof.

Specifically, cationic dyes include methylene blue, safranin 0, malachite green, cyanine dye, and rhodamine dye.

[0020] Examples of borate anions include triphenylbutylborate and trianisylbutylborate. These are suitable anions because they easily dissociate into triphenylborane or trianisylborane and butyl radicals. The amount added is 1wt% or less, especially 0.2 to 0.5w as a photocurable composition.
It is about t%.

Even if this polymerization initiator is used, since the acrylic monomer used as the curable base material is generally an anaerobic monomer, an autooxidizing agent such as N,N-dialkylaniline may be used together with the polymerization initiator. preferable. Specific examples include 2,6-diisopropyl-N,N-dimethylaniline, 2,6-diethyl-N,N-dimethylaniline, N,N,2,4,6-pentamethylaniline,
Examples include pt-butyl-N,N-dimethylaniline. The concentration is 1 to 10 wt%, especially 4 to 10 wt%.
5 wt% is preferred.

Dye precursors include cyan leuco dyes, magenta leuco dyes, and yellow leuco dyes that develop colors by reacting with acid compounds, and have lactones,
Practically colorless compounds having a lactam, sultone, spiropyran, ester or amide structure, such as triarylmethane compounds, bisphenylmethane compounds, xanthene compounds, fluoranes, thiazine compounds, spirolane compounds, and crystal violet lactones are often used. It will be done.

In order to form microcapsules, these are mixed with wall-forming materials such as gelatin, gum arabic, polyvinyl alcohol, carboxymethyl cellulose, resorcinol-formaldehyde, isocyanate-polyol, urea-formaldehyde, and urea-resorcinol-formaldehyde.

Furthermore, when developing and transferring a color pattern after exposure to light, it is a preferred embodiment to use a small amount of a solvent for the dye precursor in order to ensure the transfer of the dye precursor from the photosensitive film to the transparent substrate. .

[0025] Using such raw materials, microcapsules are formed by a conventional method, but the smaller the capsule size, the better the resolution of the pattern, but the resistance to rupture of the microcapsules increases during development and transfer. 0
．． The thickness should be about 1 to 15 μm, preferably about 1 to 5 μm.

In this way, microcapsules of cyan leuco dye, magenta leuco dye, and yellow leuco dye are obtained, but in the present invention, after mixing these three,
It is applied to a non-stretchable film to make a photosensitive film. In this case, a four-part mixture may be performed by mixing microcapsules containing a dye precursor that develops black color. As a result of the above, a photosensitive film is obtained, but since the microcapsules are photosensitive, it is necessary to store them in a dark place not only during the manufacturing process but also after the product is manufactured.

The photosensitive film is made by exposing the color filter pattern to light by direct contact or using a stepper, and then exposing the surface of the transparent substrate coated with the acid compound and the surface of the exposed microcapsules of the photosensitive film. When pressed together, the microcapsules release radicals when they encounter light in the unique spectral sensitivity band of the photopolymerization initiator, polymerize and cure the curable substrate, and release the dye precursor even under pressure. do not. Furthermore, since the photopolymerization initiator does not generate radicals even when exposed to light outside the spectral sensitivity band, this microcapsule ruptures when pressure is applied, releasing the dye precursor, which reacts with the acid compound on the transparent substrate to develop the color. do. Color development in this case is performed by a subtractive color method.

After peeling off the photosensitive film, a surface protective film such as a transparent synthetic resin solution is applied to the colored transparent substrate to obtain a color filter for liquid crystal.

[0029]

[Operation] The present invention was completed by focusing on the fact that color patterns are formed using photosensitive microcapsules whose accuracy has been significantly improved in recent years.

The dye may be colored by a subtractive color method, and by making the particle size of the microcapsules fine, the precision and resolution of the color pattern can be improved.

Therefore, it is fully expected that the color, precision, and resolution of the color pattern forming method of the present invention will improve as these basic materials develop in the future.

[0032]

【Example】

(Transparent substrate) A transparent glass plate with a thickness of 1.0 mm was cleaned with ethyl alcohol, and 10 parts by weight of polyvinyl butyral was added as a binder and 5 parts by weight of an acid compound.
A mixture of parts by weight of phenol formaldehyde resin was made into a 10% by weight solution in ethyl alcohol, and this was applied by spin coating and dried to form a coating film with a thickness of 1 μm.

(Photosensitive film) Microcapsules containing dye precursors of cyan leuco dye, magenta leuco dye, and yellow leuco dye, a curable base material containing a polymerization initiator, an autooxidizing agent, a solvent for image forming agent, etc. A commercially available "SIRIS (Mead Corporation, USA) sheet" can be used as a photosensitive film in which a layer of the mixture is applied to a biaxially stretched polyester film.

(Exposure) Photographic original patterns for blue light, green light, and red light are sequentially used as color filter patterns, and the photosensitive film is exposed to blue light, green light, and red light, respectively. conduct.

(Development) The transparent substrate and the exposed photosensitive film with the color filter pattern were stacked and pressed together. A pattern corresponding to each photo original pattern is formed on the transparent substrate. This color pattern is formed to correspond to each photographic original, and has good accuracy and resolution.

[0036]

Effects of the Invention The color filter substrate of the present invention has particularly simplified exposure and development compared to conventional color filter manufacturing methods, and resist coating, pattern exposure, development, dyeing, and resist peeling for each color light. There is no need to repeat the process, only three exposures are required for each photographic original pattern, and only one resist coating, developing, dyeing, and resist stripping process is sufficient. Further, if the original pattern is a colored color filter, it may be directly brought into close contact with white light and exposed. In any case, it is an excellent method that greatly shortens complex and long processes, helps reduce costs, and has sufficient accuracy.

Claims (4)

[Claims] Claim 1: A transparent substrate and a non-stretchable film provided with a layer containing a compound that is essentially an acid;
For liquid crystal images consisting of a curable substrate that is cured by green and red light and a photosensitive film coated with microcapsules consisting of complementary color dye precursors that react with acid to form dyes corresponding to the respective light. Color filter substrate. 2. The curable substrate according to claim 1, wherein the curable substrate is a free radically polymerizable monofunctional or polyfunctional ethylenically unsaturated organic compound containing a photopolymerization initiator, an oligomer or prepolymer of the compound, or a mixture thereof. Color filter substrate for LCD images. 3. The color for liquid crystal images according to claim 1, wherein the dye precursor contains a photosensitizer and a cyan leuco dye that reacts with red light, a magenta leuco dye that reacts with green light, and a yellow leuco dye that reacts with blue light. filter board. 4. The photosensitive film of the color filter substrate for liquid crystal images of claim 1 is exposed to the color pattern of the color filter for liquid crystal images, and this is pressed together with the acid compound-containing surface of the transparent substrate, A method for forming a color pattern of a color filter for a liquid crystal image, the method comprising developing and transferring the pattern onto a transparent substrate.