KR20090124756A - Method for preparing a pigment dispersion composition for color filter - Google Patents

Abstract

PURPOSE: A pigment dispersion composition is provided to ensure excellent transparency, contrast, storage stability, and to prepare pigment dispersion color resist and ink with stable quality because color property and viscosity are not changed in long storage. CONSTITUTION: A method for preparing a pigment dispersion composition comprises the steps of: dispersing pigment in an organic solvent; and aging the composition in which pigment is dispersed. The composition in which pigment is dispersed performs aging at 35-100 °C for 2-120 hours. In the dispersion step, pigment is pulverized to the particle size of 50-150 nm. The pigment is organic pigment.

Description

Manufacturing method of pigment dispersion composition for color filters {METHOD FOR PREPARING A PIGMENT DISPERSION COMPOSITION FOR COLOR FILTER}

The present invention relates to a process for preparing a pigment dispersion composition, in particular a process for preparing a pigment dispersion composition useful for color filters.

There are dyeing method, pigment dispersion method, electrodeposition method, printing method, etc. to manufacture color filters. Pigment dispersion method is currently applied to mass production mainly considering productivity, quality and cost. Recently, new technologies such as film transfer method, inkjet printing method, and laser transfer method have been developed to improve problems such as improvement of color characteristics, color manufacturing, color production, and large area substrates.

The color filter is manufactured by forming patterns of three primary colors, that is, red, green, and blue on a glass substrate, and a process of manufacturing a color pattern by a pigment dispersion method is performed using a spin coater or the like. Uniformly applying a color resist containing a pigment corresponding to each color pixel on the substrate; Heat-drying the applied composition to form a film; Selectively exposing the dried film using a mask having a desired shape, and then developing the dried film; And curing the developed film by heating.

Since the color filter of the liquid crystal display device requires particularly high transparency, it is useful to use it as a color filter only when very fine pigment is uniformly dispersed in the transparent vehicle. However, when the fine pigment particles are dispersed in a transparent vehicle, it is difficult to obtain a stable dispersion composition, and it is known to cause various problems in the physical properties of the final product. First, in the process of dispersing a fine pigment, the pigment dispersion composition exhibits high viscosity, making it difficult to produce a product, or a problem that the viscosity of the pigment dispersion composition increases during storage. Pigment dispersion compositions that are poor in storage stability have a tendency to decrease in brightness and color sharpness during storage. Therefore, in order to produce a color filter having excellent transparency and color sharpness, a technique for stably dispersing finer pigments becomes most important.

In order to disperse | distribute a fine pigment stably, especially the selection of the dispersing agent and resin for dispersion which have a big influence on the dispersion stability of a pigment is very important. However, if the dispersant is used too much, the storage stability is greatly improved, but the development speed may be slowed in the alkaline developer, and residues may occur after the development process. Polymers with high acid value are mainly used to disperse the resin in aqueous alkali solution, but pigment dispersion composition containing a high acid value resin tends to cause agglomeration of pigments, which leads to high viscosity. Therefore, the storage stability of the pigment dispersion composition is often worsened.

When the pigment dispersion color resist is prepared with a pigment dispersion composition having weak dispersion stability, the pigment dispersion color resist is spin-coated because pigment particles tend to gradually aggregate, viscosity increases, or thixotropy tends to increase. When the coating is performed by, the film thickness of the color resist is changed in the substrate, resulting in poor coating film uniformity.

Therefore, it is very important that the pigment dispersion composition is a Newtonian fluid and its physical properties do not change for a long time.

In order to solve the various problems mentioned above, the method of using the pigment derivative which has a pigment as a mother skeleton and has an acidic group and a basic group as a substituent in a side chain as a dispersing adjuvant is proposed (for example, Japanese patent publication 41-2466). US Patent No. 2855403, Japanese Patent Application Laid-Open No. 63-305173, Japanese Patent Application Laid-Open No. 1-247468, Japanese Patent Publication No. 3-26767, Japanese Patent Publication No. 5-72943, Japanese Patent Publication No. 8- 48890).

Moreover, use of the copolymer which has an alkyleneoxy group as a dispersing agent is also proposed (for example, refer Unexamined-Japanese-Patent No. 62-25164, Unexamined-Japanese-Patent No. 4-223468, and Unexamined-Japanese-Patent No. 5-39450). .

However, the above methods do not yet provide a pigment dispersion composition for preparing a color filter having sufficiently good storage stability, transparency and clarity.

As an improvement due to the thickening, the film thickness increase, and the transmittance of the pigment dispersed color resist during long-term storage, Korean Patent Publication No. 2002-0070832 proposes to carry out the heating process when manufacturing the color resist. However, in the above process, the storage stability of the pigment dispersion color resist is often worsened depending on the pigment dispersion composition.

Accordingly, an object of the present invention is to provide a method for producing a pigment dispersion composition for producing a color filter having excellent storage stability, transparency and color clarity.

In accordance with the above object, the present invention provides a method for producing a pigment dispersion composition comprising the step of dispersing the pigment in an organic solvent and aging the composition in which the pigment is dispersed.

Here, the aging temperature of the composition in which the pigment is dispersed is preferably 35 to 100 ° C, and the aging time is preferably performed for 2 to 120 hours.

It is also preferable to grind the pigment to a particle size of 50 to 150 nm in the dispersing step.

In the present invention, the pigment is preferably an organic pigment.

And when disperse | distributing a pigment to an organic solvent, it is preferable to disperse | distribute one or more of a dispersing agent, a resin for dispersion, and a dispersing aid together.

Here, the content of the pigment is preferably 5 to 50% by weight based on the total weight of the composition.

Moreover, it is preferable that the said resin for dispersion is a polymer containing the monomeric unit which has a carboxyl group, and content is 1 to 50 weight% based on the composition total weight.

In addition, the dispersant is an acrylic block copolymer, polyurethane, polyethyleneimine or a mixture thereof, and the content is preferably 1 to 50% by weight based on the total weight of the composition.

In addition, the dispersing aid has an acidic group or a basic group as a substituent, the content is preferably 0.1 to 5% by weight based on the total weight of the composition.

The present invention also provides a pigment dispersion composition obtained by the above methods.

The present invention also provides a pigment dispersion color resist comprising the pigment dispersion composition obtained by the above methods.

The pigment dispersion composition obtained by the present invention is excellent in transparency, contrast and storage stability, and can be usefully used for producing pigment dispersion color resists and high-quality inks. Even after long-term storage, there is no change in color characteristics and viscosity, so that pigment dispersion color resists and inks of stable quality can be prepared.

Pigment dispersion process is a process of physically crushing the pigment by applying a high shear force to the pigment requires a lot of energy, it is common to use beads with a diameter of 0.05 to 2.0mm to maximize the physical impact force. Beads include glass, stainless steel, and zirconium.

Dispersers used in the production of pigment dispersion compositions include bead mills, roll mills, attritors, super mills, dissolvers, homomixers, sand mills, 3-roll mills, disc mills, paintsakers, scandex, and the like. Wheat is the most used.

The pigment dispersion composition is prepared through a dispersion process. The dispersion process includes a wetting dispersion stabilization step and a grinding step. After the proper amount of each component of the pigment dispersion composition is added, the pigment powder is wetted while mixing with a stirrer. The order of addition of the composition may also affect the storage stability of the pigment dispersion composition. Preferably, the pigment, the dispersing aid, the dispersant, the binder resin is preferably added in order.

The wet mixture is ground to pigment particles to a particle size of 50 to 150 nm using the disperser. Since the pigment particles in the pigment dispersion composition, which have undergone a dispersion process in which excessive shearing force is applied, are thermodynamically unstable, they try to aggregate in a direction to reduce the specific surface area of the pigment particles. In particular, the ultrafine particles excessively dispersed in the dispersion process have a greater tendency to aggregate. When the pigment particles aggregate, the viscosity increases and the average size of the particles increases. When the dispersing aid and dispersant mentioned in the present invention are used, the aggregation of the pigment particles does not proceed continuously, but the viscosity and the average particle size of the pigment dispersion composition change over time.

Aging of the pigment dispersion composition that has undergone the dispersion process at a certain temperature for a certain time lowers the viscosity, and reduces the average size of the pigment particles, thereby improving transparency and color purity. The activity of the dispersing aid and dispersant is maximized at high temperature, so it adheres well to the pigment particles and promotes the acid-base bond of the dispersing agent in the acidic / basic period of the dispersing agent, thereby greatly improving the storage stability of the pigment dispersion composition. .

The temperature at which the pigment dispersion composition is aged is 35 to 100 ° C, preferably 40 to 80 ° C. When the aging temperature is a low temperature outside the above range, the effect of aging is not at all exhibited, and when the temperature is too high, the storage stability of the pigment dispersion composition may be rather deteriorated.

The time for aging the pigment dispersion composition is 2 to 120 hours. If the aging time is too long outside the above range, the storage stability of the pigment dispersion composition is rather deteriorated, so it is most advantageous to determine the shortest time for which the aging effect is seen. In general, when the temperature is high, the ripening effect appears in a short time, so the ripening time is reduced.

The pigment dispersion composition of the present invention may include a pigment, a dispersing aid, a dispersant, a resin for dispersing, an organic solvent, and other additives.

The pigment used in the present invention can be used without particular limitation as long as it is an organic pigment having high transparency, color sharpness and heat resistance. Specific examples of such compounds include C.I. Pigment yellow No. 12, C.I. Pigment Yellow No. 17, C.I. Pigment Yellow No. 20, C.I. Pigment Yellow No. 86, C.I. Pigment Yellow No. 110, C.I. Pigment Yellow No. 117, C.I. Pigment Yellow No. 125, C.I. Pigment Yellow No. 128, C.I. Pigment Yellow 137, C.I. Pigment Yellow 138, C.I. Pigment Yellow No. 139, C.I. Pigment Yellow No. 147, C.I. Pigment Yellow 148, C.I. Pigment Yellow No. 150, C.I. Pigment Yellow 153, C.I. Pigment Yellow 154, C.I. Pigment Yellow 166, C.I. Pigment yellow 185;

C.I. Pigment orange 36, C.I. Pigment Orange No. 38, C.I. Pigment Orange No. 40, C.I. Pigment Orange No. 42, C.I. Pigment Orange No. 43, C.I. Pigment Orange No. 51, C.I. Pigment Orange No. 55, C.I. Pigment Orange No. 59, C.I. Pigment Orange No. 61, C.I. Pigment Orange 64, C.I. Pigment Orange 65, C.I. Pigment Orange 71, C.I. Pigment orange 73;

C.I. Pigment red No. 9, C.I. Pigment Red No. 97, C.I. Pigment Red No. 122, C.I. Pigment Red 123, C.I. Pigment Red 144, C.I. Pigment Red 149, C.I. Pigment Red 166, C.I. Pigment Red 168, C.I. Pigment Red 176, C.I. Pigment Red No. 177, C.I. Pigment Red No. 180, C.I. Pigment Red 192, C.I. Pigment Red 215, C.I. Pigment Red 216, C.I. Pigment Red 224, C.I. Pigment Red No. 254, C.I. Pigment Red 255, C.I. Pigment Red No. 264, C.I. Pigment red 265;

C.I. Pigment blue No. 15, C.I. Pigment Blue 15: 3, C.I. Pigment Blue 15: 4, C.I. Pigment Blue 15: 6, C.I. Pigment Blue No. 60, C.I. Pigment Blue No. 64, C.I. Pigment blue 80;

C.I. Pigment violet 1, C.I. Pigment Purple No. 19, C.I. Pigment violet 23, C.I pigment violet 29, C.I pigment violet 32; And

C.I. Pigment green No. 7, C.I. Pigment Green No. 36, C.I. Pigment green 58, etc. are mentioned. These organic pigments can be used individually or in combination of 2 or more types, respectively.

Generally 5-50 weight% is preferable and, as for content of the pigment in the pigment dispersion composition of this invention, 10-30 weight% is more preferable. When the content of the pigment is too high, the viscosity stability of the pigment dispersion composition becomes worse.

As for resin for dispersion which can be used for the pigment dispersion composition of this invention, the polymer containing the monomeric unit which has a carboxyl group is preferable. Examples of the monomer having a carboxyl group include acrylic acid, methacrylic acid, maleic acid, fumaric acid and the like having one or more carboxyl groups in a molecule. These monomers are compounds having a carbon-carbon unsaturated bond, and can be used alone or in combination of two or more. Specific examples thereof include aromatic vinyl compounds such as styrene and vinyltoluene, unsaturated carboxylate compounds such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, Vinyl carboxylate compounds such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, benzyl acrylate, benzyl methacrylate, and unsaturated aminoalkyl carboxylate compounds such as aminoethyl acrylate, such as vinyl These monomers, such as acetate and vinyl propionate, are used individually or in combination of 2 or more types, respectively.

It is preferable that the acid value of the said resin for dispersion is 50-150. If the acid value is too high, the storage stability of the pigment dispersion composition is worsened, and if it is too low, there occurs a problem that the developing speed for the alkaline developer is slow. The acid value unit is expressed in milligrams (mg) of potassium hydroxide required to neutralize 1 g of the resin for dispersion. In addition, the acid value of the said resin for dispersion can be adjusted with the molar ratio of the monomer which comprises resin. As a weight average molecular weight of resin for dispersion, 5,000-100,000 are preferable.

Generally 1-50 weight% is preferable and, as for content of resin for dispersion | distribution in the pigment dispersion composition of this invention, 1-10 weight% is more preferable.

The dispersant that can be used in the pigment dispersion composition of the present invention is an acrylic block copolymer, polyurethane, polyethyleneimine-based or a mixture thereof, and is characterized by including an amine group as a pigment affinity group.

Commercially available dispersants include disperbyk-160, dispervick-161, dispervick-165, dispervick-168, dispervick-170, and dispervick available from BYK-Chemie. -171, Dispervic -2000, Dispervic -2001, EFKA-4046, EFKA-4047, EFKA-4340 from EFKA, Solsperse-24000 from Avesia, Solsper-32500, AJINOMOTO PB-821, PB-822, PB-824, and PB-827 can be used. These dispersants can be used individually or in combination of 2 or more types, respectively. The content of the dispersant having a pigment affinity group in the pigment dispersion composition of the present invention is 1 to 20% by weight, more preferably 1 to 10% by weight. In the present invention, since the dispersant is used for dispersion and dispersion stability of the organic pigment, it is preferable to use a small amount. If too much is used, the storage stability of the pigment dispersion composition may be excellent, but the development speed for the alkaline developer is slow when the pigment dispersion color resist is prepared, and undeveloped residue remains after development.

The dispersing aid that can be used in the pigment dispersion composition of the present invention is characterized by having a molecular structure having affinity with an organic pigment as a mother nucleus and having an acidic group or a basic group as a substituent. Commercially available dispersing agents include Solves-5000, Solsperth-12000, Solsperth-22000, BYP-Kemi Chemistry Dispervic-2100, Dispervic-2105, EFKA EFKA-6746 and EFKA-6750. These dispersing aids can be used individually or in combination of 2 or more types, respectively. The content of the dispersion aid in the pigment dispersion composition of the present invention is 0.1 to 5% by weight, more preferably 0.1 to 2% by weight.

In the pigment dispersion composition of the present invention, as the organic solvent for dispersing the pigment, resin, dispersant and dispersing aid, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol Alkylene glycol monoalkyl ethers, such as monomethyl ether and ethylene glycol monoethyl ether, and these ester esters, such as methyl ethyl ketone, acetone, methyl isobutyl ketone, and cyclohexanone ethanol, propanol, butanol, hexanol, cyclo Alcohols such as hexanol, ethylene glycol, diethylene glycol, glycerin and the like. These may be used individually by 1 type and may use 2 or more types together.

As content in the said pigment dispersion composition of the said organic solvent, it is 50 to 90 weight%, Preferably it is 60 to 80 weight%.

As an additive used for the pigment dispersion composition of this invention, surfactant, an organic acid, etc. can be used. Use of a suitable surfactant is preferred because the dispersion stability of the pigment is further improved. When the organic acid is properly mixed, it was confirmed that the thermal stability and alkali developability of the pigment dispersion composition may be improved.

The pigment dispersion composition of this invention can be used also as a coating material, a printing ink, etc. Moreover, it can also supply as a pigment-disperse color resist which can be image-formed by light irradiation by mixing with a photosensitive composition.

The pigment dispersion color resist contains the pigment dispersion composition of the present invention, a polyfunctional monomer having two or more unsaturated double bonds, and a photopolymerization initiator. Since it contains the pigment dispersion composition of this invention, it is excellent in permeability | transparence and color sharpness, and also excellent in the storage stability of a composition.

Hereinafter, the present invention will be described in detail by way of examples. However, the following examples are merely to illustrate the invention, but the content of the present invention is not limited to the following examples.

1. Preparation of Pigment Dispersion Composition

Example 1

Pigment Green No. 36 10 wt% and Pigment Yellow No.150 5 wt%, Dispersant PB-821 (Ajinomo Tosa) 5 wt%, Acrylic resin (molecular weight 20,000, solid content 40%, acid value 100) 2 wt%, Dispersion aid brush -12000 (Avecia Co., Ltd.) 1.5% by weight and propylene glycol monomethyl ether acetate (PGMEA) 76.5% by weight, blended, stirred, and dispersed in a vertical bead mill, the pigment dispersion composition obtained by stirring at 45 ℃ 72 hours, cooled and green A pigment dispersion composition was obtained.

Example 2

Pigment Green No. 36 10 wt%, Pigment Yellow No.138 138 5 wt%, Dispersant PB-821 5 wt%, Acrylic resin (molecular weight 20,000, solid content 40%, acid value 100) 2 wt%, Dispersion aid Solsper-12000 1.5 wt% And 76.5% by weight of PGMEA were mixed and stirred, followed by cooling the pigment dispersion composition obtained by dispersing with a vertical beads mill at 45 ° C. for 72 hours to obtain a green pigment dispersion composition.

Example 3

Pigment Blue 15: 6 15% by weight, 5% by weight of dispersant PB-821, 2% by weight of acrylic resin (molecular weight 20,000, solid content 40%, acid value 100), 1.5% by weight of dispersing aid Solsper-12000 and 76.5% by weight of PGMEA After mixing and stirring, the pigment dispersion composition obtained by dispersing with a vertical beads mill was stirred after stirring at 45 ° C. for 72 hours to obtain a blue pigment dispersion composition.

Example 4

15% by weight of Pigment Red No. 254, 5% by weight of Dispervic-2001 (BYK-Khemisa), 2% by weight of acrylic resin (molecular weight 20,000, solid content 40%, acid value 100), 1.5% by weight of dispersing aid Solsper-22000 and After mixing and stirring 76.5% by weight of PGMEA, the pigment dispersion composition obtained by dispersing with a vertical bead mill was stirred after stirring at 45 ° C. for 72 hours to obtain a pigment red dispersion composition.

Example 5

After the preparation in the same manner as in Example 1, the mixture was stirred at 60 ° C. for 24 hours and then cooled to obtain a green pigment dispersion composition.

Comparative Example 1

A green pigment dispersion composition prepared in the same manner as in Example 1 and not subjected to a aging process.

Comparative Example 2

A green pigment dispersion composition prepared in the same manner as in Example 2 and not subjected to a aging process.

Comparative Example 3

Pigment blue dispersion composition prepared in the same manner as in Example 3 and not subjected to a aging process.

Comparative Example 4

Pigment red dispersion composition prepared in the same manner as in Example 4 and not subjected to a aging process.

2. Color Characteristic Evaluation Test of Pigment Dispersion Composition

50% by weight of the pigment dispersion composition obtained in Examples 1 to 5 and Comparative Examples 1 to 4 and 50% by weight of the acrylic resin (molecular weight 20,000, solid content 40%, acid value 100) were mixed and sufficiently stirred to prepare a resin mixture. The film was formed using a spin coater and dried in an oven at 100 ° C. for 10 minutes to obtain a coating film of a pigment dispersion composition. The coating film was measured for (x, y, Y) in a C light source using a colorimeter MCPD-3000 manufactured by Otsuka Corporation. The minimum and maximum luminance values were measured using the luminance meter LS-100 manufactured by Minolta and the polarizer of LG Chemicals, and the contrast value (= maximum luminance value / minimum luminance value) was obtained. In summary.

3. Storage stability evaluation test of pigment dispersion composition

Initial viscosity was measured at 60 rpm of the pigment dispersion composition obtained in Examples 1-5 and Comparative Examples 1-4 using LDVE II by the Brookfield company. After putting into a low temperature incubator maintained at 45 ℃ 7 days, 14 days, 28 days after the viscosity was measured by checking the viscosity change over time. The experimental results are summarized in Table 1 below. In general, a viscosity change of less than 10% for 4 weeks can be used as a good pigment dispersion composition.

◎: viscosity change within 10%, △: viscosity change within 50%, X: viscosity change 50% or more

Claims (11)

A method of producing a pigment dispersion composition comprising the step of dispersing the pigment in an organic solvent and aging the composition in which the pigment is dispersed. The method of claim 1, A method for producing a pigment dispersion composition, characterized in that the aging of the composition in which the pigment is dispersed is carried out at 35 to 100 ° C. for 2 to 120 hours. The method of claim 1, A method for producing a pigment dispersion composition, characterized in that the pigment is ground to a particle size of 50 to 150nm in the dispersing step. The method of claim 1, A method for producing a pigment dispersion composition, characterized in that the pigment is an organic pigment. The method of claim 1, A method for producing a pigment dispersion composition, characterized in that when dispersing the pigment in an organic solvent, one or more of a dispersant, a resin for dispersing, and a dispersing aid are dispersed together. The method of claim 1, Content of the pigment is a method for producing a pigment dispersion composition, characterized in that 5 to 50% by weight based on the total weight of the composition. The method of claim 5, The said resin for dispersion is a polymer containing the monomer unit which has a carboxyl group, and content is 1 to 50 weight% based on the composition total weight, The manufacturing method of the pigment dispersion composition characterized by the above-mentioned. The method of claim 5, The dispersant is an acrylic block copolymer, polyurethane, polyethyleneimine or mixtures thereof, and the content is 1 to 50% by weight based on the total weight of the composition. The method of claim 5, The dispersing aid has an acidic group or a basic group as a substituent, the content is 0.1 to 5% by weight based on the total weight of the composition. A pigment dispersion composition obtained by the method according to any one of claims 1 to 9. A pigment dispersion color resist comprising the pigment dispersion composition of claim 10.