JP2008003387A - Method for manufacturing color filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a color filter for preventing color mixing between adjoining pixels upon manufacturing a color filter by use of an ink-jet system. <P>SOLUTION: The method includes the steps of: forming a light shielding layer in a predetermined pattern on a transparent substrate; discharging color materials of the respective colors onto openings of the light shielding layer to obtain a specified arrangement by an ink-jet method to form a color layer having a first film thickness; vaporizing the solvent in the color layer to reduce the film thickness of the color layer into a second film thickness smaller than the first film thickness; and heat treating the color layer. The ratio (T2/T1) of the second film thickness (T2) to the first film thickness (T1) is 0.6 to 0.95. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a color filter used for a color liquid crystal display, and more particularly to a method for manufacturing a color filter using an inkjet method.

  In recent years, with the development of mobile phones, personal computers, and thin color televisions, the demand for color LCDs has increased. In particular, the size of thin color televisions has increased significantly. However, as the demand for large-sized thin color TVs increases, the cost reduction is remarkable, and among the components of thin color TVs, there is a high demand for cost reduction of color filters having high specific gravity.

  Such a color filter usually has a coloring pattern of three primary colors of red (R), green (G), and blue (B), and the electrodes corresponding to the R, G, and B pixels are turned on / off. As a result, the liquid crystal operates as a shutter, and light passes through each of the R, G, and B pixels, and color display is performed.

  As a conventional method for producing a color filter, for example, a staining method can be mentioned. In this dyeing method, a transparent water-soluble polymer material is first patterned on a glass substrate into a desired shape by photolithography, and the obtained transparent pattern is immersed in an aqueous dye solution to dye the transparent pattern. By repeating the process once, R, G and B color filter layers are formed.

  Another method is a pigment dispersion method. In this method, a photosensitive resin layer in which a pigment is dispersed is first formed on a substrate, and this is patterned to obtain a monochromatic pattern. Further, this process is repeated three times to form R, G, and B color filter layers.

Still another method includes a method in which a pigment is dispersed in a thermosetting resin, R, G, and B are printed three times, and then the resin is thermoset.
However, in any method, in order to color the three colors of R, G, and B, it is necessary to repeat the same process three times, which increases the cost, and the yield decreases because the same process is repeated. There is a problem.

  In recent years, a method for manufacturing a color filter using an inkjet method has been studied as a method for manufacturing a color filter that solves these problems.

  Examples of a method for producing a color filter using an inkjet method include methods described in Patent Document 1, Patent Document 2, Patent Document 3, and the like.

  In Patent Document 1, in order to prevent the color ink from spreading outside a desired color region on the glass substrate, a color ink in which a fluorine-based water / oil repellent is previously contained in a black matrix (light-shielding pattern) is used. Describes that the colored ink is fixed only in the colored region. Patent Document 2 and Patent Document 3 describe that a black matrix containing a fluorine-containing compound and / or a silicon-containing compound is used as a partition wall for bleeding in ink in a coloring process and preventing color mixing. .

  Patent Document 4 discloses that the ink repellency at the top of the light shielding pattern and the ink repellency between the light shielding patterns are 90 to 120 ° and 30 ° or less, respectively, with respect to the light shielding pattern. An invention is disclosed in which the spreading of the colored ink is improved and the colored ink is less likely to adhere to the upper part of the light shielding pattern. In the present invention, the surface of the light shielding pattern is treated with the ink-philic treatment agent to control the ink repellency.

However, even if the black matrix contains a fluorine compound or silicon compound that is a water repellent as in the conventional method described above, color mixing tends to occur when the amount of ink filling the black matrix opening is large, Yield decreases. In addition, if the water repellent is contained excessively, it evaporates at the time of post-baking (main curing) which is the final step of the black matrix formation step, and thinly adheres to the glass substrate surface exposed to the black matrix opening, When the ink is filled, the wettability between the surface of the glass substrate and the ink is deteriorated, and there is a problem that the ink does not spread uniformly in the opening and white spots and color unevenness occur.
JP-A-6-347637 JP-A-7-35915 JP 7-35917 A JP-A-9-203803

  The present invention has been made under the circumstances as described above, and an object of the present invention is to provide a method of manufacturing a color filter that improves the flatness in pixels when manufacturing a color filter using an ink jet method.

  In order to solve the above-described problems, the present invention provides a step of forming a light-shielding layer having a predetermined pattern on a transparent substrate, and discharges colored materials of respective colors into the openings of the light-shielding layer so as to have a predetermined arrangement by an inkjet method. A step of forming a colored layer having a first thickness, a step of evaporating a solvent in the colored layer, and setting a thickness of the colored layer to a second thickness smaller than the first thickness, and A step of heat-treating the colored layer, wherein a ratio (T2 / T1) of the second film thickness (T2) to the first film thickness (T1) is 0.6 to 0.95. A method for manufacturing a color filter is provided.

  In such a color filter manufacturing method, the ratio (T2 / T1) of the second film thickness (T2) to the first film thickness (T1) is preferably 0.6 to 0.8.

  The coloring material for forming the colored layer by the inkjet method preferably contains a pigment, a binder resin, and two or more organic solvents, and 10 to 50% by weight of the organic solvent is a solvent having a boiling point of 160 ° C. or lower. .

  Further, the evaporation rate of the organic solvent is desirably 20 or more when the evaporation rate of butyl acetate is 100.

  Examples of the binder resin include one or more thermosetting resins selected from the group consisting of polyester resins, acrylic resins, epoxy resins, melamine resins, and benzoguanamine resins. In this case, the weight average molecular weight of the thermosetting resin is desirably 500 to 10,000.

  The present invention also provides a color filter manufactured by the color filter manufacturing method described above.

  According to the present invention, the colored layer formed by the ink jet method is allowed to stand at room temperature, the thickness is reduced to a predetermined ratio, and then the colored layer is heat-cured. A flat colored layer can be obtained, whereby a color filter without color unevenness can be produced.

  The best mode for carrying out the invention will be described below.

FIG. 1 is a cross-sectional view showing a method of manufacturing a color filter according to an embodiment of the present invention in the order of steps. First, as shown in FIG. 1A, a photocurable shielding layer 2 constituting a partition is provided on a transparent substrate 1.
The transparent substrate 1 may be a plastic sheet and a plastic film such as polycarbonate, polyethersulfone, and polyacrylate as long as the transparency as a color filter and the mechanical strength characteristics are satisfied. For this, a glass substrate is used. The glass substrate is excellent in transparency, strength, heat resistance, and weather resistance.

  The shielding layer 2 is provided on the transparent substrate 1 using a photocurable ink composition. The ink composition is obtained by forming a black pigment, an ink binder resin, a photoinitiator, a water repellent, and the like into an ink using a solvent. This ink composition can be applied onto the transparent substrate 1 by using a coating method such as a bar coater, a roll coater, a spin coater, a die coater, or a gravure coater.

  As a black pigment contained in the ink composition, a general pigment such as an organic black pigment or an inorganic black pigment can be used. For example, organic pigments, carbon black, aniline black, graphite, titanium oxide, iron black and the like can be used alone or in combination.

  The water repellent contained in the ink composition has a role of repelling the colored composition when filled with the colored composition and preventing entry into adjacent pixels. The material of the water repellent is not particularly limited, but a fluorine compound or a silicon compound is preferable because of excellent water repellency. However, when the ink filling amount into the black matrix opening increases, the colored composition enters the adjacent pixels, resulting in poor color mixing.

  In addition, if an excessive amount of water repellent is contained, it evaporates during the post-baking (main curing) that is the final step of the black matrix formation step, and thinly adheres to the glass substrate surface exposed to the black matrix opening. When the ink is applied, the wettability between the surface of the glass substrate and the ink deteriorates, the ink does not spread uniformly in the opening, and white spots and color unevenness occur.

  Specific examples of water repellents include those having an organic silicone or alkyl fluoro group in the main chain or side chain, silicone resins and silicone rubbers containing a siloxane component, and other vinylidene fluoride and vinyl fluoride. Fluorine resins such as ethylene trifluoride and their copolymers can be mentioned, but are not limited thereto.

  Next, as shown in FIG. 1B, light irradiation is performed through a photomask 3, the shielding layer 2 is cured into a pattern, and a process such as development is performed, as shown in FIG. 1C. Thus, a black matrix (BM) substrate having the light shielding pattern 4 can be obtained.

  As the exposure means for the shielding layer 2, for example, one that emits light having a wavelength with which a radically polymerizable compound reacts, such as an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a xenon lamp, or a halogen lamp can be used.

  As the developing solution for the shielding layer 2, a solution capable of dissolving the non-exposed portion, for example, an alkaline aqueous solution such as sodium hydroxide or sodium carbonate can be used.

  After the light shielding pattern 4 is formed, a general cleaning process (water cleaning, air cleaning, etc.) is performed, and then heating (post-baking) can be arbitrarily performed. As a result, the patterned resin layer can be sufficiently heat-cured, and the ink repellency of the BM can be further enhanced by the effect of eluting the ink repellent agent from the BM surface. The heating temperature is, for example, 120 ° C. to 250 ° C., and the heating time is about 3 minutes to 60 minutes.

  Thereafter, as shown in FIG. 1 (d), a plurality of colored compositions are ejected into the openings of the light shielding pattern 4 by an inkjet method, for example, a red colored layer 5a, a green colored layer 5b, and a blue colored layer 5c. Form.

  As an apparatus used for the ink jet method, there are a piezo conversion method and a heat conversion method depending on a difference in an ink discharge method, but it is desirable to use a piezo conversion method device. Also. The ink atomization frequency of the ink jet apparatus is desirably about 5 to 100 kHz. Furthermore, the nozzle diameter of the ink jet apparatus is desirably about 5 to 80 μm. Furthermore, it is preferable to use an inkjet apparatus in which a plurality of heads are arranged and about 60 to 500 nozzles are incorporated in one head.

  The coloring composition used in the present invention contains a pigment, a binder resin, and at least two kinds of organic solvents, and the organic solvent has a boiling point of 160 ° C. or less, preferably 10 to 50% by weight, preferably 20 to 40% by weight. Is preferably composed of a solvent at 120 ° C. or lower.

  The evaporation property of the ink is improved by comprising 10 to 50% by weight of an organic solvent having a boiling point of 160 ° C. or less among at least two kinds of organic solvents. The ink volume is instantaneously reduced after ink jet ejection, so that the coloring composition can be prevented from entering adjacent pixels and color mixing can be prevented.

  On the other hand, in the case where 10 to 50% by weight is composed of an organic solvent having a boiling point of more than 160 ° C., the ratio of film thickness reduction can be set within a predetermined range when it is allowed to cool at room temperature thereafter. It becomes difficult, and the film thickness becomes non-uniform during heat curing, resulting in uneven color. When the content of the solvent having a boiling point of 160 ° C. or lower exceeds 50% by weight, the colored composition is rapidly dried at the tip of the discharge head, which causes a sudden increase in ink viscosity and clogging. It may adversely affect straightness and stability.

  Examples of the organic solvent having a boiling point of 160 ° C. or lower include isopropyl acetate, propyl acetate, isobutyl acetate, butyl acetate, pentyl acetate, isopentyl acetate, ethyl lactate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, and cyclohexanone. It is done. Of course, it is also possible to use a mixture of these organic solvents.

  On the other hand, it is also necessary to add an organic solvent having a boiling point of 160 ° C. or higher in order to ensure the linearity and stability of ejection. For example, diethylene glycol-n-butyl ether, tetraethylene glycol dimethyl ether, pentaethylene glycol dimethyl ether, tripropylene glycol methyl ether, dipropylene glycol-n-propyl ether, dipropylene glycol-n-butyl ether, tripropylene glycol-n-butyl ether, propylene Glycol phenyl ether, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 2-ethoxyethyl acetate, 2-butoxyethyl acetate, 2-methoxyethyl acetate, 2-ethoxyethyl acetate, 2- (2-ethoxyethoxy ) Ethanol, 2- (2-butoxyethoxy) ethanol, 2- (2-ethoxyethoxy) ethyl acetate, - (2-butoxyethoxy) ethyl acetate, 2-phenoxyethanol, can be used diethylene glycol dimethyl ether and the like.

  As the pigment for the inkjet coloring composition, it is preferable to use a pigment having excellent weather resistance. Specifically, Pigment Red 9, 19, 38, 43, 97, 122, 123, 144, 149, 166, 168, 177, 179, 180, 192, 208, 215, 216, 217, 220, 223, 224, 226, 227, 228, 240, 254, Pigment Blue 15, 15: 6, 16, 22, 29, 60, 64, Pigment Green 7, 36, Pigment Yellow 20, 24, 86, 81, 83, 93, 108, 109, 110 117, 125, 137, 138, 139, 147, 148, 150, 153, 154, 166, 168, 185, Pigment Orange 36, Pigment Violet 23, and the like can be used. Furthermore, in order to obtain a desired hue, a mixture of two or more pigments can be used.

  The binder resin of the coloring composition is preferably a thermosetting resin from the viewpoint of simplifying the color filter production apparatus and the production process. In particular, polyester resins, acrylic resins, and epoxy resins, which are thermosetting resins with little thermal yellowing to satisfy the physical properties required for color filters, such as solvent resistance, alkali resistance, acid resistance, and heat resistance. One or more selected from the group consisting of resins, melamine resins, and benzoguanamine resins are used.

  Further, the weight average molecular weight of the binder resin is preferably in the range of 500 to 10,000, and particularly preferably in the range of 500 to 8,000. When the weight average molecular weight of the binder resin exceeds 10,000, the fluidity of the ink is insufficient during the heat processing of the colored layer, resulting in poor pattern flatness.

  The dispersant for the coloring composition can be used to improve the dispersibility of the pigment in the solvent. As the dispersant, an ionic or nonionic surfactant can be used. Specific examples include sodium alkylbenzene sulfonate, poly fatty acid salts, fatty acid salt alkyl phosphates, tetraalkyl ammonium salts, polyoxyethylene alkyl ethers, and other organic pigment derivatives and polyesters. One type of dispersant may be used alone, or two or more types of dispersants may be mixed and used as necessary.

  After forming the red colored layer 5a, the green colored layer 5b, and the blue colored layer 5c, it is allowed to stand at room temperature for 2 to 10 minutes. As a result, the film thickness T1 of the colored layers 5a, 5b, and 5c decreases due to the evaporation of the solvent in each colored layer, and becomes T2 as shown in FIG.

  Thus, after forming the colored layers 5a, 5b, and 5c, the film thickness is decreased by leaving it for the following reason.

  That is, in the inkjet method, the nozzle is clogged when the colored composition is made high in concentration. Therefore, the ink is usually discharged to the BM opening at a low concentration. However, the film thickness greatly increases due to the heat treatment of the colored layer containing a large amount of solvent. Considering such a reduction, the thickness of the discharged colored layer must be increased. When a heat treatment is performed to cure after forming a thick colored layer with a large amount of solvent, the film thickness decreases due to rapid solvent evaporation, resulting in non-uniform film thickness and uneven color. End up.

  On the other hand, in the present invention, a coloring material is ejected to the opening of the BM by an ink jet method to form a colored layer, which is then left at room temperature, and the thickness of the colored layer is set to the post-ejection film thickness T1. The film thickness ratio T2 is reduced at a rate such that the film thickness ratio (T2 / T1) is 0.6 to 0.95, preferably 0.6 to 0.8. By reducing the film thickness at such a ratio and then performing a heat treatment, a colored layer having a uniform film thickness can be obtained, and color unevenness does not occur.

  When the ratio (T2 / T1) of the second film thickness (T2) after cooling to the first film thickness (T1) after discharging by the inkjet method is less than 0.6, it takes a long time for cooling. The colored layer after pre-baking becomes a film. That is, a large amount of the solvent on the surface evaporates to form a film, and if this is baked, the surface is wrinkled. On the other hand, when T2 / T1 exceeds 0.95, the film thickness becomes non-uniform during heat curing and color unevenness occurs.

  After allowing to cool at room temperature, the transparent substrate 1 provided with the light shielding pattern 4 and the colored layers 5a, 5b, and 5c is introduced into a heating furnace, and the colored layers 5a, 5b, and 5c are pre-baked at 100 to 150 ° C. Further, post-baking is performed at 200 to 250 ° C. As a result, the colored layers 5a, 5b, and 5c are cured, and the film thickness thereof is substantially the same as the film thickness of the light shielding pattern 4 as shown in FIG.

Thereafter, as shown in FIG. 1 (g), a protective layer 6 is formed on the surface to complete the color filter.
The protective layer 6 is provided in order to improve the smoothness and weather resistance of the color filter surface. The protective layer 6 is prepared by coating a compound having a carboxyl group and a compound having an epoxy group dissolved in a solvent or the like using an appropriate coating method such as a spin coating method or a die coating method, followed by heating to crosslink. Can be formed.

  The compound having a carboxyl group may be a compound having a carboxyl group that can be crosslinked with an epoxy group by heating. By the way, since a carboxyl group and an epoxy group have high reactivity, a problem may arise in a manufacturing process. For this reason, it is desirable to use a compound in which the carboxyl group is blocked with an alkyl vinyl ether.

  Specific examples of the compound having a carboxyl group include 1-isopropoxyethyl (meth) acrylate, 1-ethoxyethyl (meth) acrylate, 1-t-butoxyethyl (meth) acrylate, 1- (1-methylhexyloxy) Ethyl (meth) acrylate, 1- (1,1-dimethylpropoxy) ethyl (meth) acrylate, 1-isopropoxyethyl (meth) acrylamide, 1-ethoxyethyl (meth) acrylamide, 1-t-butoxyethyl (meta ) Acrylamide, 1- (1-methylhexyloxy) ethyl (meth) acrylamide, 1- (1,1-dimethylpropoxy) ethyl (meth) acrylamide, 1,2,4-benzenetricarboxylic acid-2,4-bis ( Propoxyethyl) -1-((meth) acryloxyethyl) ester, etc. Monomers or copolymer as an example.

  Examples of the compound having an epoxy group include monomers such as glycidyl (meth) acrylate, glycidyl itaconate, glycidyl fumarate, 3,4-epoxycyclohexyl (meth) acrylate, and copolymers. In particular, when an acrylic resin is used as the compound having an epoxy group, the protective layer 6 having excellent transparency and weather resistance can be obtained.

  Examples of the present invention will be described below in more detail, but the present invention is not limited to these examples.

Example 1. Preparation of black matrix 10 parts by weight of polyimide precursor (“Semicofine SP-510” manufactured by Toray Industries, Inc.), 7.5 parts by weight of carbon black, 130 parts by weight of NMP, 5 parts by weight of dispersant (copper phthalocyanine derivative), start 5 parts by weight of the agent and 0.5 parts by weight of the ink repellent agent (polyalkylsiloxane) were dispersed with a bead mill disperser for 3 hours while cooling to prepare a black matrix composition.

  The prepared black matrix composition was applied on alkali-free glass (product number 1737: manufactured by Corning) by spin coating, and then pre-baked at 90 ° C. for 20 minutes in an oven.

  Next, after exposure and development, post baking was performed in an oven at 230 ° C. for 1 hour to form a black matrix. The film thickness of the formed black matrix was 1.5 μm.

  The contact angle of the top of the black matrix thus formed with the colored ink (surface tension 30 mN / m) was measured and found to be 30 °, and the top of the black matrix exhibited ink repellency with respect to the colored ink. Confirmed to have.

2. Preparation of coloring composition The following were used as a pigment which colors the coloring composition used for color filter preparation. That is, CIPigment Red 254 ("Irga Four Red B-CF": manufactured by Ciba Specialty Chemicals) is used as a red pigment, and CIPigment Blue 15; 6 ("Heliogen Blue": manufactured by BASF) is used as a blue pigment. The composition shown in Table 1 below was sufficiently kneaded by bead mill dispersion to prepare a red pigment dispersion (Compositions 1 and 2) and a blue pigment dispersion (Composition 3).

To the pigment dispersion thus obtained, a thermosetting resin and an organic solvent were added according to the formulation shown in Table 2 below, and the mixture was stirred well to prepare nine color filter coloring compositions (inks A to I). did.

3. Production of color filter substrate Color composition of red (R) and blue (B) colors by an ink jet printer equipped with a 12 pl, 180 dpi head (manufactured by Seiko Instruments Inc.) in an opening of a black matrix formed on a glass substrate The object was discharged. Then, it is naturally dried at room temperature, and after decreasing at various ratios (T2 / T1) as shown in Table 3 below until the thickness T1 of the colored layer reaches T2, it is 100 ° C. and 120 ° C. on a hot plate. Then, pre-baking was performed at 150 ° C. for 3 minutes, and post-baking was further performed at 230 ° C. for 20 minutes to form a patterned colored layer, thereby obtaining 60 types of color filter samples.

  About these color filter samples, the shape of the colored layer of each color of red (R) and blue (B) was observed and evaluated according to the following criteria. The results are shown in Table 3 below.

: The surface is very flat (ΔEab of the minimum film thickness and maximum film thickness in the pixel is 2 or less)
○: The surface is flat (ΔEab of the minimum film thickness part and the maximum film thickness part in the pixel is 2 to 3)
Δ: The surface is almost flat (ΔEab between the minimum film thickness portion and the maximum film thickness portion in the pixel is 3 to 5).
X: The surface is non-uniform, convex or film-like (ΔEab of the minimum film thickness and maximum film thickness in the pixel is 5 or more)

上記表３から、以下のことが明らかである。即ち、Ｔ２／Ｔ１が０．６未満の場合（例６、例１２、例２６、例３２、例４６、例５２）には、着色層はいずれも皮膜状となり、一方、Ｔ２／Ｔ１が０．９５を超えると（例１、例７、例１３、例１４、例２１、例２７、例２８、例３３、例３４、例４１、例４７、例５３）、着色層はいずれも表面が不均一か凸形状となり、好ましくない。

From Table 3 above, the following is clear. That is, when T2 / T1 is less than 0.6 (Example 6, Example 12, Example 26, Example 32, Example 46, and Example 52), the colored layers are all in the form of a film, while T2 / T1 is 0. ..95 (Example 1, Example 7, Example 13, Example 14, Example 21, Example 27, Example 28, Example 33, Example 34, Example 41, Example 47, Example 53) Uneven or convex shape is undesirable.

  On the other hand, when T2 / T1 is in the range of 0.6 to 0.95, the colored layer shows a good shape in any case.

  Moreover, when T2 / T1 is in the range of 0.6 to 0.9, it is understood that a particularly excellent shape is exhibited when a solvent having a boiling point of 160 ° C. or lower is used.

It is sectional drawing which shows an example of the manufacturing process of the color filter which concerns on one Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Transparent substrate, 2 ... Shielding layer, 3 ... Photomask, 4 ... Light shielding pattern, 5a ..., 5b ... Green colored layer, 5c ... Blue colored layer, 6 ... Protective layer.

Claims (7)

Forming a light shielding layer of a predetermined pattern on a transparent substrate;
A step of discharging a coloring material of each color into the opening of the light shielding layer so as to have a prescribed arrangement by an ink jet method to form a colored layer having a first film thickness;
Evaporating the solvent in the colored layer to make the thickness of the colored layer a second thickness smaller than the first thickness; and heat-treating the colored layer,
The method of manufacturing a color filter, wherein a ratio (T2 / T1) of the second film thickness (T2) to the first film thickness (T1) is 0.6 to 0.95.   The ratio (T2 / T1) of the second film thickness (T2) to the first film thickness (T1) is 0.6 to 0.8, The color filter according to claim 1, Production method.   The color according to claim 1, wherein the coloring material includes a pigment, a binder resin, and two or more organic solvents, and 10 to 50% by weight of the organic solvent is a solvent having a boiling point of 160 ° C or lower. A method for manufacturing a filter.   The method for producing a color filter according to claim 3, wherein the evaporation rate of the organic solvent is 20 or more when the evaporation rate of butyl acetate is 100.   The binder resin is one or more thermosetting resins selected from the group consisting of polyester resins, acrylic resins, epoxy resins, melamine resins, and benzoguanamine resins. 5. A method for producing a color filter according to 4.   6. The method for producing a color filter according to claim 5, wherein the thermosetting resin has a weight average molecular weight of 500 to 10,000.   The color filter manufactured by the manufacturing method of the color filter in any one of Claims 1-6.

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