JPH05247354A - Photo-setting coloring composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition excellent in shelf life, photo-setting properties, dispersibility and compatibility and useful, e.g. as a color filter of a liquid crystal device by adding a water soluble photosetting resin and boric acid (salt) to a specified aqueous colorant dispersion. CONSTITUTION:The objective composition is obtained by copolymerizing four or more kinds of monomers such as 2-hydroxyethyl methacrylate, dimethylacrylamide, acrylic acid, methacrylic acid and methacrylamide and adding the resultant synthesized water soluble photosetting resin and boric acid (salt) preferably in an amount of 50 to 1wt.% (based on the partially saponified polyvinyl acetate mentioned below) to an aqueous colorant dispersion composed of powdery pigments such as an azo-pigment dispersed using a partially saponified polyvinyl acetate having 70 to 95mol% saponification degree as a dispersant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocurable coloring composition, and more particularly to a composition which is cured by irradiation with light to form a colored film.

[0002]

2. Description of the Related Art Photocurable resins, which are also called photosensitive resins, are now indispensable for making electronic machinery. Further, a photocurable coloring composition obtained by adding a pigment powder to a photocurable resin is useful for making a color filter of a liquid crystal element, a color separation filter for printing, and the like.

The above-mentioned color filter is made by closely providing a large number of fine regions having different hues on a transparent substrate. The photocurable coloring composition is a perfect material for providing a large number of such fine regions having different hues close to each other. This is because the photocurable composition is applied as a paint to a thickness of a few microns on a transparent substrate, a photomask is laid on top of this, and light is applied to the area to be colored. This is because if only the curable resin in that region is cured, and then the uncured resin is dissolved and removed by a developing solution, a large number of regions deeply colored in one color can be provided in the desired shape. After that, add another color to other areas in the same way,
It can be said that. In the above example, the resin that hardens when exposed to light has been described as an example, but a colored region can be provided by using a resin that decomposes when exposed to light.

To carry out the above method, it is necessary to disperse the pigment powder in a solution of the photocurable resin. In this case, it was expedient to use water as the solvent as well as the dispersion medium to make the solution and the dispersion. The reason is,
This is because if water is used as the solvent and the dispersion medium, the risk of fire is small, the working environment is good, the device for recovering the solvent from the waste liquid is not required, and the waste liquid can be discarded as it is. Therefore, it was preferred to use water as a medium for the photocurable coloring composition.

When a photocurable coloring composition is prepared by using water as a medium, a partially saponified polyvinyl acetate (hereinafter referred to as partially saponified PVA) is often used as a dispersant for dispersing the pigment powder. Was given. This is because the partially saponified PVA disperses the pigment well, is well compatible with other water-soluble resins, and gives a good photocurable coloring composition.

However, it cannot be said that the aqueous solution of the coloring composition containing the partially saponified PVA has good storage stability. This is because if the aqueous solution is left for a while, the pigment powder will agglomerate. The deterioration of the coloring composition due to the agglomeration of the pigment powder cannot be understood only by applying this by a usual method to form a film, but the thickness of about 1 micron required for a color filter of a liquid crystal element is not understood. When a thin film is irradiated with light and the resin is cured to form an image, it can be clearly seen that the pigment powder is agglomerated.
The reason for this is that the thin film thus obtained has poor transparency when the coloring composition is deteriorated, and therefore only a blurred image can be obtained. Further, when the image is further examined at this time, it is recognized that undissolved residue remains in the portion removed by the development, which also deteriorates the image.

When the partial saponification PVA is used as a dispersant,
The reason why the pigment powder aggregates over time is not clear. Presumably, the reason seems to be that the layer of partially saponified PVA encapsulating the pigment powder migrates to the aqueous phase over time, thus losing its protective effect. Further, when an acrylic resin is used as the curable resin, the relative concentration of the partial saponification PVA in the system is lowered, and thus it is considered that the protective effect is reduced to cause instability. Since PVA is well compatible with the acrylic resin, it is possible that the partially saponified PVA is replaced with the acrylic resin dissolved in water and, as a result, the protective action of the pigment powder is lost.

On the other hand, in order to improve the above-mentioned drawbacks of partially saponified PVA, it has been proposed to use partially saponified PVA by acetalizing it with aldehydes. Therefore, the present inventor tried to acetalize the partially saponified PVA with an aldehyde such as glutaraldehyde or glyoxal. However, it did not give satisfactory results. This is because the partially saponified PVA may rather increase the water solubility in the early stage of acetalization as the acetalization progresses, and it is necessary to raise the degree of acetalization to a certain degree or more. However, when trying to increase the degree of acetalization, the part of the saponification P dissolved in the aqueous solution is
This is because even VA is converted into an acetal, and when this is used as a film, the film becomes non-uniform and a fine and transparent image cannot be obtained. Therefore, it has been necessary to improve the drawbacks of partially saponified PVA by another method.

[0009]

SUMMARY OF THE INVENTION The present invention has been made with the object of remedying the above-mentioned drawbacks. That is, a photocurable colored composition that gives a clear image even when the pigment powder is stably dispersed in an aqueous solution of the photocurable resin or is used after being stored for a long time is provided. It was made in an attempt.

[0010]

The present inventor has prepared a photocurable composition by adding a pigment dispersion prepared by dispersing partially saponified PVA in water as a dispersant into an aqueous photocurable acrylic resin solution. In order to stabilize this composition,
It has been found that it is preferable to add boric acid or a salt thereof. That is, when boric acid or a salt thereof is added to the above-mentioned photocurable composition, even if it is stored for a long time and then coated and irradiated with light to form an image, the obtained image becomes clear. It was confirmed. The present invention has been completed based on such knowledge.

The present invention relates to a photocurable coloring composition obtained by adding a water-soluble photocurable resin and boric acid or a salt thereof to an aqueous colored dispersion in which a pigment powder is dispersed with a partially saponified PVA as a dispersant. It is a thing.

It is known to use dispersants to disperse pigments. As the dispersant, generally, a surfactant,
A water-soluble polymer is used. The water-soluble polymer is, for example, polyvinylpyrrolidone, partially saponified PVA, vinylpyrrolidone / vinyl acetate copolymer, carboxymethyl cellulose, or the like. In the present invention, partial saponification PVA is particularly selected from the above water-soluble polymers. In the present invention, the use of a surfactant as a dispersant together with the partially saponified PVA is not hindered. Surfactants include anionic, cationic and nonionic ones, of which it is preferable to use nonionic ones.

In the present invention, various pigments can be used. It can be roughly divided into an organic material and an inorganic material. However, when it is used for producing a color filter, it is preferable to use an organic pigment having a wide range of selection of a transmitted light spectrum. As organic pigments, azo-based, phthalocyanine-based, anthraquinone-based, quinacridone-based, perylene-based, quinophthalone-based, thioindigo-based,
Various types such as isoindolinone-based, dioxazine-based, indathuron-based, and benzimidazolone-based can be used.

The pigment is preferably used in the form of fine powder. As fine powder, the size of the pigment particles is
If it is larger than the wavelength of the light of that color, it looks cloudy, so it is preferable that the average particle diameter is 0.2 micron or less. In order to disperse the pigment, it is preferable to previously disperse the fine pigment powder in an aqueous solution containing a dispersant, and to add this dispersion to the aqueous solution of the copolymer and mix them. A turbo mixer, a ball mill, an attritor, a bead mill, or the like can be used to prepare a dispersion of pigment fine powder.

Generally, the higher the degree of saponification of the partially saponified PVA, the easier it is to dissolve in water, but the pigment dispersibility becomes insufficient. Further, as the partial saponification PVA, the dispersion stability of the pigment is improved as the saponification degree is lowered, but the cloud point is lowered, so that a saponification degree that is too low cannot be used. Due to these restrictions, the partially saponified PVA preferably has a saponification degree of 70 to 95 mol%.

When the degree of polymerization of the partially saponified PVA becomes high, it becomes difficult to dissolve it in water. On the contrary, when it is too low, the pigment dispersibility and the compatibility with the photocurable resin deteriorate. Therefore, in the present invention, it is preferable to use a polymerization degree of 800-2000.

It has long been known that boric acid and borax act as thickeners or gelling agents for aqueous solutions of polyvinyl alcohol (hereinafter referred to as PVA). For example, boric acid or a salt thereof was considered to gel PVA by forming a monodiol-type or diol-type bond with PVA. What is the monodiol type?

[0018]

[Chemical 1] It has a structure represented by

[0019]

[Chemical 2] The structure is represented by. This structure had a thermoplastic property and became a gel at low temperature but became a sol at high temperature. This property is utilized when used as an adhesive. However, utilizing this property as a dispersant for dispersing pigment powder is completely new.

Boric acid and its salts have a function of coagulating PVA, but their coagulating action is not strong. Therefore, boric acid and its salts do not exhibit sufficient force to completely immobilize the PVA surrounding and protecting the pigment powder. Instead, it also does not exert enough force to phase separate even PVA dissolved in water. Therefore, boric acid and its salts have a moderate coagulating effect on the PVA which surrounds and stabilizes the pigment powder, and serves to stabilize the pigment powder.

Further, boric acid and its salts generally have the property that they have no great influence on water-soluble resins other than PVA and partially saponified PVA. For example, an acrylic copolymer containing 2-hydroxyethyl methacrylate as a main component has a large number of hydroxyl groups similar to PVA or partially-saponified PVA, and is a water-soluble resin having a similar structure, but boric acid and its salt. Does not show a coagulation action on acrylic polymers, unlike PVA or partially saponified PVA. This is why boric acid and its salts are particularly suitable.

In the present invention, a water-soluble photocurable resin is used. The water-soluble resin used here is the first
First, it is required that the pigment powder is well compatible with the partial saponification PVA and that phase separation does not occur. Secondly, it is necessary that the pigment powder is not aggregated. Thirdly, the thermal stability is good and even when heated. It is required not to be colored, and fourth, it is required to be difficult to react with boric acid or a salt thereof.

As the resin satisfying the above-mentioned requirements, it is considered that various monomers are polymerized alone or copolymerized. For example, vinyl hirolidone, acrylamide, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, diacetone acrylamide, dimethyl acrylamide, dimethylamino acrylate, dimethylamino methacrylate, dimethylaminopropyl acrylamide, dimethylaminopropyl methacrylamide, acrylic acid, methacryl Homopolymers or copolymers such as acids could be used.

To homopolymerize or copolymerize the above-mentioned monomers, these monomers are dissolved in a suitable solvent and polymerized. As the solvent, an organic solvent such as methyl cellosolve or dimethylformamide can be used, but water is preferably used. In particular, the use of water containing up to 20% by weight of acetic acid. A polymerization initiator is used for polymerization, and when water is used as a solvent, ammonium persulfate, 2,2′-azobis (N, N′-dimethyleneisobutylamidine) hydrochloride, 2,2′-azobis is used. (2-amidinopropane) hydrochloride, 4,4'-azobis (4-cyanopentanoic acid), 2,2'-azobis {2-methyl-N [1,1-bis (hydroxymethyl)
2-Hydroxyethyl] propionamide} and the like can be used.

From the viewpoint of thermal stability of the obtained polymer, it is desirable that the ratio of the amino group-containing monomer is as small as possible. Further, since the composition according to the present invention is intended for the purpose of curing by irradiation with light, from this aspect, a monomer containing active hydrogen,
Particularly, those using acrylic ester or methacrylic ester having a hydroxyl group as a monomer are suitable.

In order to obtain a composition which cures when irradiated with light, it is desirable to have a photosensitizer present therein.
The photosensitizer is a kind of cross-linking agent, and is a compound that acts to cross-link a monomer, polymer or copolymer existing therein when irradiated with light. When a polymer or copolymer of an acrylic ester or a methacrylic ester having a hydroxyl group is used as the water-soluble resin, a water-soluble diazo resin or a water-soluble polyfunctional aromatic azide compound is suitable as the photosensitizer.

The water-soluble diazo resin is a resin prepared by adding formaldehyde to an aromatic diazonium compound and condensing it. Examples of aromatic diazonium compounds include p-diazodiphenylamine, 2,5-
Examples thereof include dimethoxy-4-p-tolylmercaptobenzenediazonium and 2,5-dimethoxy-4-morpholinobenzenediazonium.

The polyfunctional aromatic azide compound is an aromatic compound having two or more azido groups in one molecule. For example, 4,4'-diazidostilbene-
Sodium 2,2'-disulfonate, 2,6-bis (4
-Azidobenzal) acetone-2-sulfonic acid, 2,
6-bis (4-azidobenzal) cyclohexanone-
2,2'-disulfonic acid, 2,6-bis (4-azidobenzal) acetone-2,2'-disulfonic acid and the like.

The composition according to the present invention is used in the state of an aqueous solution. To this end, an aqueous colored dispersion is prepared by dispersing pigment powder using partially saponified polyvinyl acetate as a dispersant, and separately from this, an aqueous solution of a water-soluble resin, an aqueous solution of a photosensitizer, and an aqueous solution of boric acid or a salt thereof. It is good to prepare and mix these aqueous solutions. The mixing ratio is preferably such that in the above aqueous colored dispersion, the pigment powder occupies 10 to 20% by weight of the whole dispersion, and the partial saponification PVA occupies 10 to 200% by weight of the pigment powder. Among them, saponification PVA
Preferably accounts for 50-100% by weight. Also, the water-soluble resin is 3 parts by weight per 100 parts by weight of the pigment powder.
0 to 200 parts by weight, and the photosensitizer is the above water-soluble resin 100.
It is preferably 5 to 30 parts by weight with respect to parts by weight.

The amount of boric acid and its salt added is partly saponified PV.
If the amount is much larger than A, not only does the partial saponification PVA and the photocurable resin solidify or phase separates,
Reduces photosensitivity. On the contrary, if the addition amount of boric acid and its salt is small, the effect is not sufficiently exhibited. Therefore, there is a certain limit to the amount of boric acid and its salt to be added. As for the limit, the upper limit is 50% by weight and the lower limit is 1% by weight based on the partial saponified PVA. Among them, boric acid and salts thereof are preferably used within the range of 10 to 5% by weight with respect to the partially saponified PVA.

Even within the above range, when boric acid or its salt is added as a solid or concentrated solution, the resin aqueous solution may agglomerate due to shock. Therefore, boric acid or a salt thereof is used in a low-concentration aqueous solution such as 2-3.
It is preferably added as a wt% aqueous solution. In particular, when adding sodium borate, it is preferable to use an aqueous solution having a lower concentration.

In addition, the amount of boric acid or a salt thereof to be added is preferably changed depending on the type of boric acid or a salt thereof, the state at which it is added, and the degree of saponification of partially saponified PVA. For example, since sodium borate has a stronger gelling action than boric acid, sodium borate may be added in a fraction of boric acid. Also, a partial saponification PVA with a saponification degree of 90%
When boric acid is added at room temperature to a pigment dispersion that uses as a dispersant, boric acid accounts for 1% by weight based on the entire pigment dispersion.
The following is preferable. However, when boric acid is added at a normal temperature to a pigment dispersion using a partially dispersed PVA having a saponification degree of 75% and excellent dispersibility as a dispersant, boric acid is effective even in a fraction of the above case. Is.

[0033]

According to the present invention, since the partial saponification PVA is used to disperse the pigment powder in water, the pigment powder is well dispersed in water, to which other water-soluble resin or photosensitizer is added. However, it does not suddenly hinder the dispersion of the pigment powder. However, if the above pigment dispersion containing the water-soluble resin is allowed to stand for a while and then a thin film of micron order is formed from this dispersion, the film looks cloudy and a good colored image cannot be obtained. However, in the composition of the present invention, since boric acid or a salt thereof is added to the above pigment dispersion, the dispersion of the pigment powder becomes stable, and after the dispersion is stored for a long time, a thin film of micron order is formed. Even if it is made, the film is transparent and a clear image can be obtained. Therefore, the photocurable coloring composition of the present invention is a suitable material for producing a color filter of a liquid crystal element or a color separation filter for printing. The present invention thus brings great benefits.

The advantages of the present invention will be described in detail below with reference to Examples and Comparative Examples. In the following, simply parts or% means parts by weight or% by weight.

[0035]

Example 1

Preparation of Pigment Dispersion The following formulations were made to make the pigment dispersion. Parts saponification PVA (saponification degree 88 mol%, average degree of polymerization 1500) (Nippon Gosei Kagaku KK, Gohsenol GH-17) 10% aqueous solution 100 parts polyoxyethylene monooleyl ether 2 parts phthalocyanine blue 20 parts Put in a bead mill and stir well,
The coarse particles were removed to make a pigment dispersion having a particle size of 0.23 μm.

[0036]

[Preparation of Water-Soluble Resin Liquid] The following formulations were made to make the water-soluble resin liquid. 2-hydroxyethyl methacrylate 79 parts Acrylic acid 1 part Dimethylacrylamide 10 parts Methacrylamide 10 parts 20% Acetic acid water 200 parts Polymerization initiator (2,2'-azobis (N, N'-dimethyleneisobutylamidine) 1 part In a flask 200 parts of water was added to the mixture and heated to 70 ° C., the above-mentioned formulation was added dropwise while passing nitrogen gas through it, and the mixture was reacted for 8 hours while stirring well to obtain an aqueous solution of the copolymer.
This aqueous solution was diluted with water to make the concentration of the copolymer 10%. Then, the aqueous solution obtained by filtering this aqueous solution with a filter having a pore size of 0.2 μm was used as a water-soluble resin solution.

[0037]

[Preparation of Photosensitizer Aqueous Solution] The following formulations were prepared. Diazo resin (manufactured by Shinko Giken Co., Ltd., trade name D-013) 1 part Water 9 parts This mixture was well stirred and uniformly dissolved, then the pore size was adjusted to 0.
An aqueous photosensitizer solution was obtained by filtering with a 2 μm filter.

[0038]

[Preparation of boric acid aqueous solution] The following formulations were prepared. Boric acid 1 part Water 39 parts This formulation was thoroughly stirred and uniformly dissolved, and then filtered through a filter having a pore size of 0.2 μm.

[0039]

[Preparation of Photocurable Coloring Composition] The aqueous solution obtained above was blended in the following proportions. Pigment dispersion 10 parts Water-soluble resin liquid 10 parts Photosensitizer aqueous solution 1 part Boric acid aqueous solution 2 parts The above formulation was thoroughly stirred and the resulting aqueous solution was used as a photocurable colored composition.

[0040]

[Use Test of Photocurable Coloring Composition] The above composition was applied onto a glass plate by spin coating to obtain a coating film having a thickness of 0.5 μm. A photomask was superposed on this coating film, and ultraviolet rays of 100 mJ / cm ² were irradiated from above with a high pressure mercury lamp. When developed with 1% acetic acid water thereafter, a clear blue clear image was obtained.

The same test was carried out after leaving the above composition at 20 ° C. for 1 month, but the result was not changed.
From this, it was confirmed that the dispersion did not change when left for 1 month.

[0042]

Comparative Example 1 In the photocurable colored composition of Example 1,
Using the photocurable coloring composition obtained in the same manner as in Example 1 except that the aqueous boric acid solution was not added, a usage test was conducted in exactly the same manner as in Example 1. As a result, when the composition was prepared and allowed to stand at 20 ° C. for 1 week, an image line having a line width of 10 μm was flowed out during development, and stain was observed on the non-image line portion. As a result, it was confirmed that the photocurable colored composition was deteriorated after being left for one week.

[0043]

EXAMPLE 2 In Example 1, a pigment dispersion was prepared by using a partially saponified PVA with a saponification degree of 78 mol% and an average polymerization degree of 10.
00 part soap PVA (Nippon Gosei Chemical Co., Ltd., Gohsenol K
Except that 100 parts of a 10% solution of M-11) was used, and that an aqueous borate solution obtained by mixing 0.2 parts of borax and 99.8 parts of water was used instead of the boric acid solution. A photocurable colored composition was obtained in exactly the same manner as in Example 1.

A use test was carried out using this photocurable coloring composition. As a result, an image with good transparent coloring was obtained even after 50 days from the preparation of the composition.

[0045]

Comparative Example 2 In the photocurable colored composition of Example 2,
A photocurable coloring composition was obtained in the same manner as in Example 2 except that the borate aqueous solution was not used, and a use test was conducted using this composition in the same manner as in Example 2. .. As a result, when the composition was left for 30 days at 20 ° C. after preparation, the obtained image had stains on non-image areas.
As a result, it was confirmed that the photocurable coloring composition was deteriorated after being left for 30 days.

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI Technical display location C08L 33/00 LHU 7921-4J 33/02 LJB 7921-4J G02B 5/20 101 7348-2K G03F 3/00 7818 -2H 7/038

Claims (4)

[Claims] 1. A photocurable coloring composition comprising a water-soluble photocurable resin and boric acid or a salt thereof, which is added to an aqueous colored dispersion in which pigment powder is dispersed using partially saponified polyvinyl acetate as a dispersant. 2. The photocurable coloring composition according to claim 1, wherein a partially saponified polyvinyl acetate having a saponification degree of 70 to 95 mol% is used. 3. The photocurable coloring composition according to claim 1, wherein boric acid or a salt thereof is used in a proportion of 50 to 1% by weight based on partially saponified polyvinyl acetate. 4. The photocurable resin is at least 4 of 2-hydroxyethylmethacrylate, dimethylacrylamide, acrylic acid or methacrylic acid, and methacrylamide.
The photocurable coloring composition according to any one of claims 1 to 3, which is a copolymer obtained by copolymerizing two kinds of monomers.