JPH03212466A - Coating material and its use - Google Patents

Abstract

PURPOSE:To obtain the title coating agent capable of being made into a color filter having excellent heat resistance, comprising a specific acrylic resin, solvent and transparent pigment, by using the coating agent as an overcoat of color filter useful in coloring of liquid crystal display. CONSTITUTION:The objective coating agent consisting essentially of (A) an acrylic resin, a copolymer of (i) 10-30 pts.wt. compound shown by formula I, (ii) 10-30 pts.wt. compound shown by formula II and (iii) 35-80 pts.wt. compound shown by formula III (R1 and R2 are H or CH3; (n) is 0-4), (B) a solvent (preferably cyclohexanone or ethyl cellosolve) and (C) transparent pigment (preferably pigment consisting essentially of barium sulfate). Further, a surfactant is preferably added as a dispersant.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to a coating material that can be used as a protective layer by coating on the upper layer of colored materials such as various heat-resistant inks and various heat-resistant paints. . The present invention also relates to a color filter that can be used as an overcoat for color filters used in colorizing liquid crystal displays to provide color filters with excellent heat resistance.

<Object of the Invention> Acrylic resin can be made into a resin with excellent transparency and heat resistance by selecting the acrylic monomer.

It is used as heat-resistant paints and various colored coating agents by adding heat-resistant dyes or heat-resistant pigments to form inks. Further, by patterning the coating on the substrate, it is possible to obtain color filters having desired pattern shapes and color-coded for each color. The color filter produced in this way can be heated to 240°C
It exhibits heat resistance (spectral stability) of about 1 hour at 270°C and has excellent characteristics. However, using this upper layer,
There was no satisfactory overcoat material. Therefore, an object of the present invention is to provide an overcoat material with good heat resistance and transparency.

<Prior art> The properties required for overcoat materials are (1) transparency, (2) adhesion to color filters, (3) heat resistance of 240'C or more, (4) chemical resistance, and (5) TTO (transparent conductive). (6) Adhesion with Murakami agent, etc.

Conventionally, acrylic resin and silica-based inorganic coating materials have been used as overcoat materials provided on the upper layer of color filters. However, as color filters become larger, color filters are required to have a high degree of heat resistance, and acrylic resin has a high heat resistance (190 to 220°C).
It lacks. Although silica-based coating materials have heat resistance, they have problems such as easy cranking and lack of reliability.

<Problems to be Solved by the Invention> As mentioned above, a material with good heat resistance and transparency is required as an overcoat material for a color filter. As a result of repeated research, it was discovered that heat resistance and transparency could be achieved by highly dispersing transparent pigments in acrylic resin, and the present invention was completed.

Means for Solving the Problems> That is, the present invention is an acrylic coating material consisting of at least an acrylic resin, a solvent, and a transparent pigment, and if necessary, a dispersant for dispersing the transparent pigment is added. It is.

The monomers constituting the acrylic resin used in the present invention are: R.

Indicates hydroxyethyl methacrylate, and in R2, when R1 is H, methyl, ethyl, propyl,
Isopropyl, butyl, isobutyl, amyl, and isoamyl acrylates, and when R2 is CHff,
Each methacrylate is shown.

In addition, when synthesizing acrylic resins with these compositions, monomers that can be added in small amounts to change the properties include benzyl acrylate, phenyl acrylate, glycidyl methacrylate, acrylonitrile,
Examples include vinyl acetate, N-vinylpyrrolidone, and tetrahydrofurfuryl methacrylate, and these may partially replace or be added to (b) (C).

The acrylic resin can be obtained by copolymerizing (a), (b), and (C) described above. These (a) [have]) (
The desirable blending ratio of the monomers in C) is (a) 10 to 30
Parts by weight, (b) 10-30 parts by weight, (C) 35-80
Parts by weight.

As a solvent, methyl cellosolve, ethyl cellosolve,
Butyl cellosolve, cyclohexanone, xylene, etc. are preferred, and mixtures of these solvents may also be used, but cyclohexanone and ethyl cellosolve are particularly preferred from the viewpoint of solubility and coating properties.

Transparent pigments include palite powder (BaS04), precipitated barium sulfate (BaSO4), barium carbonate (BaC
), carbonate lime powder (CaCOz), silica powder (S
iOz), basic magnesium carbonate (MgCO3)
Alumina white (A1203/XH, O or AI
(OH)s Gloss White (AI(OH)!
+ Ba5Oi), Sachin White (CaS(la + AI
(OH) s) etc. C,1, (color index) number: 10.18.19.2
0.24.25.26.27 etc.

In these transparent pigments, particles of 0.3 μm or less account for 50% by weight or more of the total particles, and particles of 1 μm or more account for 5% by weight of the total particles.
From the viewpoint of transparency and dispersibility of the transparent pigment, it is preferable to use particles having the following particle sizes: When the particles of 0.3 μm or less are less than 50% by weight of the total particles, or 1
If the amount of particles larger than 5% by weight is greater than 5% by weight, the coating material will have poor transparency, and is particularly unsuitable for applications that require high transparency, such as overcoat materials for color filters.

Various surfactants are effective as dispersants for highly dispersing these transparent pigments. Specifically, as cations, acetamine 24, acetamine 86, cortazine 86
There is P Conch (all product names manufactured by Kao Corporation), and the anionic products include Demol P, Demol EP, and Homogenol? I-8 homogenol, shi-18, homogenol shi-9
5. Homogenol L400 (all product names manufactured by Kao Corporation). In addition, Emaruan A-6 is used as a nonionic type.
0, Rheodor 5P-LIO, Rheodor 5P-510
, Rheodol 5p-oio, Emasol L-108 Emasol 5-20 (all product names manufactured by Kao Corporation), and the like.

Further, in the present invention, a photopolymerization method can be applied when the coating layer of the coating material is partially exposed to light to be photocured and patterned. In the case of photopolymerization, various monomers and polymerization initiators can be used. Seven monomers include bifunctional and polyfunctional monomers, and the bifunctional monomers include 1゜6-hexanediol diacrylate, ethylene glycol diacrylate, neopentyl glycol diacrylate, triethylene glycol diacrylate, and bis(acryloxyethoxy). ) Bisphenol A, 3-methylbentanediol diacrylate, etc., and polyfunctional monomers include trimethylolpropane acrylate, pentaerythritol triacrylate, tris(2-hydroxyethyl)isocyanate,
Dipentaerythritol hexaacrylate, etc.
These monomers are commercially available from Showa Kobunshi Co., Ltd., Toagosei Kagaku Kogyo Co., Ltd., Celanese Chemical Co., Ltd., and the like. In addition, photopolymerization initiators include acetophenone, benzophenone, benzyl dimethyl ketal, hensyl peroxide, 2-chlorothioxanthone, etc.; Commercially available products are available from Organic Chemical Industry Co., Ltd., etc. Furthermore, in order to improve the adhesion between the substrate and the composition, various commercially available brimers may be added to the composition, or the composition may be coated after coating the substrate in advance and drying it.

The method for manufacturing the transparent pigment coating material of the present invention is as follows: (1) Adding a pigment and a dispersant to an acrylic resin and thoroughly kneading it with a stirrer such as Nerol to make a varnish; (2) Adding a photopolymerization initiator to this varnish. Step of adding acrylic photopolymerizable monomer and stirring thoroughly; ■ Coating varnish onto the substrate using a roll coater or spin coater to the desired thickness; ■ Patterning by partial exposure. The acrylic resin is a dispersion medium for the pigment, and the dispersant is an auxiliary agent to uniformly disperse the pigment in the acrylic resin. .

<In the composition described in the detailed description of the invention, there is no particular limitation on the composition ratio,
Usually, the acrylic resin is 5 to 30% by weight of the composition, the photopolymerizable monomer is 10 to 30% by weight, the photopolymerization initiator is 0.05 to 3% by weight, and the transparent pigment is 5 to 30% by weight.
The amount of the dispersant is about 0 to 3% by weight.

When producing a composition based on the present invention, the acrylic resin, solvent, transparent pigment, and dispersant are dispersed in advance using a dispersion/mixing device such as a roll mill, ball mill 1, sand mill, attritor, or the like. Also, acrylic resin, transparent pigment,
It can also be made by dispersing a dispersant in advance using a roll mill or the like, and then diluting it with a solvent or acrylic resin varnish. Note that the order of mixing and dispersion is not limited to this, and can be performed as appropriate. Further, when the composition has photopolymerizability, the composition can be patterned by adding a photopolymerizable motumer and a photopolymerization initiator.

As shown in FIG. 1 of the drawings, the resin composition obtained as described above has a transparent substrate (1) and a color filter layer (2).
An overcoat layer (
3), the color filter can be protected without impairing the color tone and transparency of the color filter layer (2).

The form of the overcoat layer (3) in FIG.
As shown in Figure 3, there is a method in which the overcoat layer is removed at the end (4) where no overcoat is required.

In order to do this, the overcoat agent is made into a photosensitive resin by giving it the property of photocuring as described above, the area to be removed is exposed to light, and then developed with an appropriate solvent.
Efficient. Of course, as shown in FIG. 3, it is also possible to apply an overcoat layer (3) over the entire surface of the color filter.

The present invention will be specifically explained below using examples. In addition, all compounding ratios in the examples are weight ratios.

<Example> Acrylic resin (20 parts of methacrylic acid, 15 parts of hydroxyethyl methacrylate, 10 parts of methyl methacrylate,
55 parts of butyl methacrylate to 300 parts of ethyl cellosolve
0.75 parts of azobisisobutyronitrile was added under a nitrogen atmosphere, and the resulting acrylic resin was reacted at 70°C for 5 hours. The resulting acrylic resin was diluted with ethyl cellosolve to a resin concentration of 10%. .

To 90.8 g of this diluted resin, 9.0 g of Palite powder (barium sulfate) as a transparent pigment and 0.2 g of Emaruan A-60 as a dispersant were added, and the mixture was sufficiently kneaded with three rolls to form a transparent varnish. It was created.

To this varnish were added 4.0 g of trimethylolpropane triacrylate as a photopolymerizable monomer and 0.8 g of henzil dimethyl kecool as a photopolymerization initiator and stirred well to obtain a transparent composition. After coating the previously created color filter with a spin coater at 1200 rpm for 1 minute,
After drying at ℃ for 20 minutes, it was exposed using a mask approximately 5 mm larger than the color filter frame (30 m J/cm").
Thereafter, the film was developed using sodium carbonate (2.5% by weight aqueous solution) to remove the non-exposed areas, and thoroughly washed with water. Since there was a possibility that a small amount of transparent pigment remained on the substrate, the overcoat on the color filter was fixed by rubbing with a soft sponge, washing with water, spin-drying, and beta-rotating at 230° C. for 1 hour.

This color filter had the following properties and exhibited desirable characteristics as a color filter for liquid crystals.

<Effects of the Invention> Although it is possible to create a color filter with good heat resistance (240'C to 270°C) from a composition obtained by dispersing colored pigments in acrylic resin, as an overcoat material used for this color filter, , excellent heat resistance and moisture resistance, and no cracks or the like. In contrast, the present invention is a color filter overcoat material with excellent heat resistance, and by dispersing transparent pigments in a highly transparent acrylic resin, the color filter remains stable even after being heat-resistant at 250°C for 1 hour. It has excellent adhesion with ITO and with ITO, and by further patterning,
It is possible to form an overcoat layer that does not impair adhesiveness with the sealant, and is extremely excellent in practical use.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a color filter, FIG. 2 is a sectional view showing an example of a color filter provided with a patterned overcoat layer, and FIG. 3 is a sectional view showing an example of a color filter provided with a patterned overcoat layer. FIG. 2 is a cross-sectional view showing an example of a color filter. (1)...Transparent substrate (2)...Color filter layer (3)...Overcoat layer (4)...End portion

Claims (4)

[Claims] (1) In an acrylic coating material consisting of at least an acrylic resin, a solvent, and a transparent pigment, the main component of the monomer composition of the acrylic resin is ▲a mathematical formula, a chemical formula, a table, etc.▼……(a) ▲a mathematical formula, There are chemical formulas, tables, etc.▼……(b) ▲There are mathematical formulas, chemical formulas, tables, etc.▼……(c) (However, R_1 and R_2 are H or CH_3, and n is an integer from 0 to 4. ), and its composition ratio is (a) 10
~30 parts by weight, (2) 10-30 parts by weight (c) 35-8
A coating material characterized by using a copolymer acrylic resin of 0 parts by weight. (2) The coating material according to claim (1), wherein a surfactant is added as a dispersant. (3) The coating material according to claim (1) or (2), wherein the transparent pigment contains barium sulfate as a main component. (4) A method of using a coating material, comprising providing the acrylic coating material of claim (1) containing a transparent pigment as an overcoat layer of a color filter.