JPH04164902A - Photopolymerizable composition for color filter - Google Patents

Abstract

PURPOSE:To obtain a photopolymerizable composition which can give a color filter having high resolution and excellent heat resistance and fastness to light and being freed from ionic impurities by a simple process by adding a plurality of specified compounds and a pigment to a specified photopolymerizable compound. CONSTITUTION:This composition is obtained by mixing a photopolymerizable compound having at least one ethylenically unsaturated double bond (e.g. dipentaerythritol hexaacrylate) with a film-forming polymeric binder (e.g. a half ester of a styrene/maleic acid copolymer), a compound of the formula, a thioxanthone compound (e.g. 2,4-diethylthioxanthone), a hexaarylbisimidazole compound [e.g. 2,2'-bis(o-chloriphenyl)-4,4',5,5'-tetraphenylbisimidazolyl], a hydrogen donor (e.g. 2-mercaptobenzothiazole) and a pigment. This composition can give a color filter having excellent fastness to light and heat resistance and good resolution and being freed from ionic impurities by a simple process.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a composition for color filters.

More specifically, the present invention relates to a photopolymerizable composition for color filters with excellent optical properties used in liquid crystal display devices, color separation devices, sensors, and the like.

Conventional technology Color solid-state image sensors are in high demand for use in VTR cameras, color-distinguishable robots, and color copiers, and color liquid crystal display devices are being replaced from CRT systems due to the trend toward lighter weight and thinner profiles. The color filter used is formed by providing fine areas colored in two or more different hues as pixels on a solid-state image sensor or a transparent substrate. Such colored thin films have conventionally been produced by dyeing methods, printing methods, etc., and when particularly high-definition images are required, the dyeing method is the mainstream method.

However, these conventional methods have the following problems. Color filters made using the dyeing method are created by forming an image on a substrate using a dyeing base material such as natural photosensitive resin such as gelatin, amine-modified polyvinyl alcohol, or amine-modified acrylic resin, and then dyeing it with dye such as acid dye. The problem is that the process is very complicated and long, as it requires resist dyeing each time the dyeing is done in different hues.

Furthermore, since the dyes and resins used generally have poor light resistance, heat resistance, and moisture resistance, color filters made using these dyes naturally have problems with reliability in terms of light resistance, heat resistance, and moisture resistance. Ta.

Printing color filters are created by printing on a substrate using ink containing pigment dispersed in thermosetting or photocuring resin, and then curing it with heat or light. They are difficult to form, and the resulting images often have problems with surface smoothness. This can be said to be the addition of a coloring material into the photosensitive resin in advance, or -
Photopolymerization initiators require ultraviolet light to generate radicals, and in the system described above in which a colorant is added internally in advance, the ultraviolet light is absorbed by the colorant and is sufficient to generate radicals. In many cases, it is difficult to form a satisfactory image.

On the other hand, hexaarylbisimidazole alone, or
Furthermore, thioxanthone compounds and p-aminophenyl ketones are used in combination in photopolymerizable printing films (for example, West German Patent Publication No. 1952804,
No. 1924317, No. 3717038, No. 3717
No. 036, JP-A-2-67558).

However, these pigments or dyes do not contain any pigments or dyes at all, or they are used only in small amounts, and when pigments or dyes are added in an amount sufficient to obtain sufficient spectral characteristics, the above-mentioned coloring materials It is difficult to form a satisfactory image due to the absorption of ultraviolet light, which poses a practical problem in producing color filters.

JP-A-1-152449 proposes a method to solve the above-mentioned problems (using a halomethyl-8-triazine compound as a photopolymerization initiator to obtain images with high resolution. However, this method When a halomethyl-8-triazine compound generates radicals by light, it liberates a halogen element, which then pulls out the hydrogen atom in the molecule to generate hydrogen halide, which dissociates to form ionic impurities. There is a problem in that it becomes .

In this way, a photopolymerizable composition for color filters that does not generate ionic impurities and contains a highly sensitive photopolymerization initiator,
This cannot be achieved using conventional technology.

(Problem to be solved by the invention) When producing a color filter, the process is simple, light fastness,
A photopolymerizable composition for color filters that has excellent heat resistance, good resolution, and does not generate ionic impurities is desired.

(Means for Solving the Problem) The present inventors have created a color filter as described above, which has a simple process, excellent light resistance and heat resistance, good resolution, and does not generate ionic impurities. As a result of diligent efforts to find a method, it was discovered that a specific colored photopolymerizable composition satisfies the above characteristics, leading to the present invention.

That is, the present invention relates to a photopolymerizable compound having at least one ethylenically unsaturated double bond, a film-forming polymer binder, a compound represented by the following formula (I), a thioxanthone compound, and a hexaarylbisimidazole. system compounds,
Provided is a photopolymerizable composition for color filters, which is characterized by containing a hydrogen donor and a pigment (formula (I)).

The photopolymerizable composition for color filters of the present invention will be explained in more detail. Examples of photopolymerizable compounds having at least one ethylenically unsaturated double bond that can be used include ethyl acrylate, butyl acrylate, hydroxyethyl acrylate, and hydroxyl as photocrosslinkable or photopolymerizable monomers, oligomers, and prepolymers. Esters of acrylic acid or methacrylic acid of monohydric or polyhydric alcohols, such as ethyl methacrylate, ethylene glycol dimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, dipentaerythritol hexaacrylate;
Polyester (meth)acrylate obtained by reacting (meth)acrylic acid with a polyester prepolymer obtained by condensing a polyhydric alcohol and a monobasic acid or a polybasic acid:
Polyurethane (meth)acrylate obtained by reacting a compound having a polyol group and two isocyanate groups and then reacting (meth)acrylic acid; an epoxy resin and (
Epoxy (meth)acrylic polyester obtained by reacting meth)acrylic acid: A polymer having a cinnamylidene group in a side chain or terminal, and a usual photopolymerizable resin.

Furthermore, as the film-forming polymer binder, any organic polymer binder can be used as long as it is compatible with the photopolymerizable resin. It is desirable to use it in the range of ~4 times. for example,
Polymethacrylic acid ester or its partial hydrolyzate;
Polyvinyl acetate or its hydrolyzate; Polystyrene; Polyvinyl butyral; Polychloroprene; Polyvinyl chloride; Chlorinated polyethylene: Chlorinated polypropylene; Polyvinylpyrrolidone: Copolymer of styrene and maleic anhydride or its half ester: Acrylic acid, acrylic A copolymer selected from a group of copolymerizable monomers such as acid ester, methacrylic acid, methacrylic ester, acrylamide, acrylonitrile, etc. and having a glass transition point of 35° C. or higher is used.

Among these, those with acidic groups such as carboxyl groups are
Aqueous development is possible and is more economical and safer than organic solvent development.

Examples of thioxanthone compounds include 2゜4-diethylthioxanthone, isopropylthioxanthone, 2.
-chlorothioxanthone, etc., and it is desirable to use it within the range of 1 to 10% by weight based on the photopolymerizable compound.

Examples of hexaarylbisimidazole compounds are US Patent-3784557 or European Patent-A24.
629, but particularly good ones include 2,2'-bis-(0-chlorophenyl)-4,
4", 5°5"-tetraphenylbismidazolyl and 2,2'-bis(0-chlorophenyl)-4°4",
5.5=-tetra-(p-methoxyphenyl)bisimidazolyl is mentioned, and 0.5 to
It is desirable to use it within a range of 10% by weight.

As the hydrogen donor, aromatic mercaptan compounds, aromatic amine compounds, etc. are used.

Among these, as aromatic mercaptan-based hydrogen donors, those with a benzene or heterocyclic core and one or two mercapto groups are preferred; in the case of two substitutions,
One of the mercapto groups may be substituted with alkyl, aralkyl, or phenyl, and furthermore, it may be a dimer with an alkylene group interposed therebetween, or a dimer in the form of a disulfide.

Particularly preferred are 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, etc., and it is desirable to use them in an amount of 0.5 to 10% by weight based on the photopolymerizable compound.

Next, the aromatic amine hydrogen donor preferably has benzene or a heterocycle as the core, and one or two amino groups, and the amino group is substituted with an alkyl group or a substituted alkyl group. You can leave it there. The monoamino compound may be further substituted with a carboxyl group, an alkoxycarbonyl group, a substituted alkoxycarbonyl group, a phenoxycarbonyl group, a substituted phenoxycarbonyl group, or a nitrile group. Particularly preferred are the following, and it is desirable to use it in an amount of 0.5 to 10% by weight based on the photopolymerizable compound.

Since it is necessary to filter visible light, the pigment used preferably has a particle size of % or less of the wavelength of the filtered light, and more preferably a pigment dispersed with an average number particle size of 200 nm or less.

Preferred examples of blue pigments include phthalocyanine pigments; red pigments include quinacridone pigments, perylene pigments, pyrrolo-virol pigments, and anthraquinone pigments; and preferred examples of green pigments include halogenated phthalocyanines. These pigments may be used alone, or other pigments may be added to adjust the color.

In addition, as pigments for black matrix, carbon,
Titanium carbon, iron oxide, azo black pigment, etc. may be used alone or in combination of two or more.

These red, green, blue, and black fine particle pigments account for 10 to 60% by weight, preferably 2% by weight, based on the photopolymerizable compound.
It is desirable to use it within the range of 0 to 50% by weight.

The photopolymerizable composition for a color filter of the present invention includes the photopolymerizable compound, a film-forming polymer, a compound represented by formula (I), a thioxanthone compound, a hexaarylbisimidazole compound, a hydrogen donor, and a pigment. It can be obtained by mixing in the proportions mentioned above. It is preferable that the mixing is performed using a mixer or a disperser while processing. The obtained composition of the present invention can also be filtered to remove coarse particles and foreign matter. When performing filtration, a filter with a pore diameter of 1μ or less, preferably 0.5μ or less is used.

A general method for preparing a color filter using the photopolymerizable composition of the present invention is as follows.

In the present invention, the photopolymerizable composition is diluted with an organic solvent (for example, methylcellosolve, ethylflusolve) as necessary to obtain a chemical solution, which is applied to a base material using a spinner or the like, and the solvent is dried. , obtain a smooth coating film. Next, in order to avoid contact between the coating film and oxygen that inhibits photopolymerization, a resin such as PVA is further applied onto the coating film and dried.

The coating film thus obtained is irradiated with ultraviolet rays through a negative mask in order to form a desired image. At this time, a device such as mask alignment is used so that all the membranes are uniformly irradiated with parallel light beams. Next, this light-irradiated coating film is exposed to running water of an alkaline aqueous solution or in a shower to dissolve the uncured portions and then developed to obtain the desired image (color filter).

The present invention will be explained in more detail with reference to Examples below.

Example 1 First, a composition having the following composition ratio was prepared.

・SMA-262530gr manufactured by Arco Chemical (styrene-maleic acid copolymer half ester) ・Dipentaerythrhexaacrylate 5gr ・2-Benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone gr ・2,4-diethylthioxanthone 0.5gr・2
, 2′-bis-(0-chlorophenyl)-4,4″, 5
．． 5--Tetraphenylbisimidazolyl
0.5gr 2-mercaptobenzothiazole 0.5gr ethyl cellosolve acetate)
100gr Next, red, green, blue, black pigment paste,
It was prepared as follows.

To 20 parts of the above pigment composition for each color, 4 parts of a sorbitan fatty acid ester compound was added as a dispersant, and further 6 parts of ethyl cellosolve acetate rough were added to perform dispersion using a sand mill.

The average number distribution of each of the red, green, and blue pigment particles dispersed here was 200 nm or less. This pigment paste was added in an amount of 40% by weight to the above composition, and after further processing in a sand mill, the mixture was passed through a 1μ filter in a pressure filtration machine to obtain a photopolymerizable composition for a color filter of the present invention.

Application Example 1 The photopolymerizable composition obtained in Example 1 was applied using a spin coater to a smooth glass plate that had been washed with water, alcohol, and Freon, and dried at 100°C for 5 minutes.

Next, a 10% polyvinyl alcohol aqueous solution was applied using a spin coater and dried at 100° C. for 5 minutes. The coating film obtained in this way was passed through a negative mask using a mask aligner MA-10 manufactured by Mikasa Co., Ltd. at a rate of 15 mJ/c.
nf exposure. The film was then baked at 100°C for 15 minutes, and developed for 60 seconds in running water of a 1% by weight aqueous sodium carbonate solution at 25°C.

The film thickness of each color of the color filter created under the above conditions is shown below.

Table 2 When this color filter was subjected to a heat resistance test at 200''C for 3 hours, no change in each color was observed, and no change in weight was observed.

Comparative Example 1 The composition shown below was prepared as a photosensitive #M resin in the same manner as in Example 1, and a color filter was produced in the same manner as in Application Example 1.

The light energy required to form an image equivalent to that of Example 1 using the composition thus obtained is shown in the table below.

Table 3 As described above, the photosensitivity of the photopolymerizable composition for color filters obtained in Comparative Example 1 was extremely poor.

Comparative Example 2 The composition shown below was prepared in the same manner as in Example 1, and a color filter was produced in the same manner as in Application Example 1.

The light energy required to form an image equivalent to Example 1 using the composition thus obtained is shown in the table below.

Table 4 As described above, the photosensitivity of the photopolymerizable composition for color filters obtained in Comparative Example 2 was extremely low.

Example 2 A photopolymerizable composition for a color filter of the present invention was obtained in the same manner as in Example 1 using the composition shown below.

Application Example 2 Using the photopolymerizable composition for color filters prepared in Example 2, a color filter was produced in the same manner as in Application Example 1. When this was subjected to a heat resistance test at 200°C for 3 hours, no discoloration or weight loss was observed. In addition, when subjected to a 100-hour carbon arc one-light test,
No discoloration was observed at all.

(Effects of the Invention) A photopolymerizable composition has been developed that enables the production of color filters that have a simple process, high resolution, good heat resistance and light resistance, and do not contain ionic impurities.

Claims (1)

[Claims] 1. A photopolymerizable compound having at least one ethylenically unsaturated double bond, a film-forming polymer binder, a compound represented by the following formula (I), a thioxanthone compound, a hexaaryl Photopolymerizable composition formula (I) for color filters characterized by containing a bisimidazole compound, a hydrogen donor, and a pigment ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ 2. The hydrogen donor is an aromatic mercaptan Photopolymerizable composition 3 according to claim 1, wherein the hydrogen donor is an aromatic compound having an amino group.
The photopolymerizable composition according to claim 2, wherein the hydrogen donor is 2-mercaptobenzothiazole or 2-mercaptobenzoxazole.