JP4839991B2 - Manufacturing method of color filter - Google Patents

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 turns on / off electrodes corresponding to the respective pixels of R, G, and B. Thus, the liquid crystal operates as a shutter, and light is transmitted 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. Thus, it is described 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. .
JP-A-6-347637 JP-A-7-35915 JP 7-35917 A

 Although the above-described color filter manufacturing method using the ink jet method can suppress the spread of the ink outside the colored region, the smoothness of the formed pixel is significantly deteriorated due to the ink repellent function of the black matrix. There was a problem that color unevenness was likely to occur.

 The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for manufacturing a color filter using an inkjet method that can improve the smoothness of a pixel.

In order to solve the above-mentioned problems, a first aspect of the present invention is a method of forming a light-shielding layer having a predetermined pattern on a transparent substrate, and a coloring composition of each color in an opening of the light-shielding layer by an inkjet method. A step of forming a colored layer of a plurality of colors by discharging in a predetermined arrangement, wherein the colored composition includes a pigment and a thermosetting resin, and a melt index (JISK7210; test) of the thermosetting resin temperature 125 ° C., test load 2.16 kgf) is 20g~100g / 10 min, 120 ° C. to 200 DEG ° C. der glass transition point is, the solid content ratio of pigment to the thermosetting resin in the colored composition The method for producing a color filter is characterized in that the mass ratio is 1: 4 to 3: 2 .

  In the method for producing a color filter configured as described above, the solid content ratio of the pigment to the thermosetting resin in the coloring composition is preferably 1: 4 to 3: 2.

  Further, it is desirable that the thermosetting resin has a melt index (JISK7210; test temperature 125 ° C., test load 2.16 kgf) of 30 to 90 g / 10 min and a glass transition point of 150 ° C. to 180 ° C.

  Furthermore, it is desirable that the light shielding layer contains a water repellent.

According to a second aspect of the present invention, a colored composition of each color is discharged into a predetermined arrangement by an inkjet method into a light shielding layer having a predetermined pattern formed on a transparent substrate, and an opening of the light shielding layer. The colored composition includes a pigment and a thermosetting resin, and has a melt index (JISK7210; test temperature of 125 ° C., test load of 2.16 kgf) of the thermosetting resin. ) Is 20 g to 100 g / 10 min, and the glass transition point is 120 ° C. to 200 ° C.

 According to the present invention, when forming a colored layer by an inkjet method, a colored composition containing a thermosetting resin having a predetermined melt index and glass transition point is used. Leveling is sufficiently performed, and the flatness of the pixel, which is a problem in manufacturing a color filter using an ink jet method, can be greatly improved, and a color filter without color unevenness can be manufactured.

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 can be used. A glass substrate is preferable because of its excellent 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 in the black matrix opening increases, the coloring 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.

  As described above, the light shielding pattern 4 contains a water repellent, so that it is possible to prevent the coloring composition from entering the adjacent pixels, and to avoid color mixing in which adjacent pixels are mixed during the production of the color filter. There is an advantage that you can. On the other hand, however, the contact angle of the colored composition to the black matrix increases, resulting in a problem that the smoothness of the colored layer after drying is lowered.

  In the production of the color filter according to the present embodiment, the coloring composition for inkjet for forming the colored layer contains a pigment and a thermosetting resin, and a melt index (JIS K7210, test temperature 125 ° C., The test load 2.16 kgf) is in the range of 20-100 g / 10 min. Preferably, it is the range of 30-100 g / 10min, More preferably, it is the range of 30-90 g / 10min. When the melt index of the thermosetting resin is smaller than 20 g / 10 minutes, the smoothness of the colored layer is inferior, and when it is larger than 100 g / 10 minutes, the storage stability of the colored composition is inferior.

  Moreover, Tg (glass transition temperature) of a thermosetting resin is 120 to 200 degreeC, Preferably it is 150 to 180 degreeC. If the Tg of the thermosetting resin is lower than 120 ° C., the chemical resistance and solvent resistance of the color filter are remarkably lowered, and if it exceeds 200 ° C., the flatness of the pixel is deteriorated, which is not preferable.

 The thermosetting resin is a thermosetting resin with little thermal yellowing to satisfy the physical properties required for color filters, such as heat resistance, hot water resistance, alkali resistance, and acid resistance. Resin, epoxy resin, melamine resin, benzoguanamine resin and the like can be used.

 The blending mass ratio of the pigment to the thermosetting resin in the colored composition for inkjet is preferably 1: 4 to 3: 2 in terms of solid content. When the amount of the thermosetting resin is insufficient with respect to the pigment, the leveling property due to the heat flow decreases, and the smoothness of the pixel tends to deteriorate. Further, if the amount of the thermosetting resin relative to the pigment is too large, the thickness of the colored layer increases, so that adjacent pixels are mixed during ink jet coating, which tends to make it difficult to produce a color filter.

 As a solvent used for the coloring composition, in consideration of suitability for ink jet printing, a solvent having a surface tension of 35 mN / m or less and a boiling point of 130 ° C. or more is preferable. If the surface tension exceeds 35 mN / m, the dot shape stability during ink jet ejection tends to be adversely affected. If the boiling point is less than 130 ° C., the drying property near the nozzle becomes remarkably high. It tends to cause defects such as clogging.

 Specifically, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 2-ethoxyethyl acetate, 2-butoxyethyl acetate, 2-methoxyethyl acetate, 2-ethoxyethyl ether, 2- (2-ethoxy Ethoxy) ethanol, 2- (2-butoxyethoxy) ethanol, 2- (2-ethoxyethoxy) ethyl acetate, 2- (2-butoxyethoxy) ethyl acetate, 2-phenoxyethanol, diethylene glycol dimethyl ether, etc. The solvent is not limited to these and can be preferably used as long as it satisfies the above-mentioned requirements. Two or more kinds of solvents may be mixed and used as necessary.

 As the pigment of the 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, two or more kinds of materials can be mixed and used.

 The dispersant for the inkjet coloring composition can be used to improve the dispersibility of the pigment in the resin. 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.

  Next, 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 90 to 150 ° C, and further 200 to 250 ° C. Post bake with. As a result, the colored layers 5a, 5b, and 5c are cured as the solvent evaporates, and a structure as shown in FIG. 1 (e) is obtained.

  Then, as shown in FIG.1 (f), the protective layer 6 is formed in the surface and a color filter is completed. The protective layer 6 is provided in order to improve the smoothness and weather resistance of the color filter surface. As the protective layer 6, a resin film of a thermosetting type, a photocuring type, a combined light / heat type, or an inorganic film formed by vapor deposition, sputtering, or the like can be used. Any color filter can be used as long as it has transparency as a color filter and can withstand the subsequent ITO formation process, alignment film formation process, and the like.

 EXAMPLES Examples of the present invention will be shown below, and the present invention will be described more specifically. However, the present invention is not limited by these examples. Each test method is as follows.

1) Measurement of melt index (MI value) DYNISCOMELT INDEXER (manufactured by Dynisco Corporation, Japan) was used as an apparatus, and measurement was performed at a temperature of 125 ° C. and a pressure of 2.16 kgf.

2) Evaluation of smoothness The film thickness profile (step difference in the pixel) and the color difference (ΔEab) in the pixel were measured by a contact-type surface shape measuring apparatus to evaluate the smoothness.

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 A black matrix composition was prepared by dispersing 5 parts by weight of an agent and 0.5 parts by weight of an ink repellent (polyalkylsiloxane) for 3 hours while cooling with a bead mill disperser.

  The prepared black matrix composition was applied on alkali-free glass (product number 1737: manufactured by Corning) by spin coating, and then prebaked 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 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 to be 30 °, and the top of the black matrix was ink repellent with respect to the colored ink. It was confirmed to have

2. Preparation of coloring composition
(A) Preparation of Pigment Dispersion Paste The following were used as colorants for coloring the colored composition used for the preparation of the color filter.

  CIPigment Blue 15: 6 (BASF “Heliogen Blue”) as a blue pigment, CIPigment Red 254 (“Irga Four Red B-CF” from Ciba Specialty Chemicals) and CIPigment Red as a red pigment 177 (Ciba Specialty Chemicals “Chromophthal Red A2B”), CIPigment Green 36 (Toyo Ink “Rionol Green 6YK”) and CIPigment Yellow 150 (Bayer ’s “Fungchon First” Yellow Y-5688 ”), red, green and blue color inks were prepared using the respective pigments.

a) Preparation of Red Pigment Dispersion Paste A mixture of the following composition was uniformly stirred and mixed, then dispersed with a sand mill for 5 hours using glass beads having a diameter of 0.5 mm, and then filtered through a 5 μm filter to obtain a red pigment dispersion paste. Got.

Red pigment: CIPigment Red 254 36 parts by weight
CIPigment Red 177 4 parts by weight Dispersant: Solsperse 20000 10 parts by weight, manufactured by Apicia, Inc. Solvent: 50 parts by weight of 2- (2-butoxyethoxy) ethyl acetate b) Preparation of green pigment dispersion paste Red pigment so that the composition is as follows It was produced by the same method as the dispersion paste.

Green pigment: CIPigment Green 36 36 parts by weight Yellow pigment: CIPigment Yellow 150 4 parts by weight Dispersing agent: Solsperse 20000 10 parts by weight manufactured by Apicia Corporation Solvent: 50 parts by weight of 2- (2-butoxyethoxy) ethyl acetate c) Blue pigment dispersion paste Preparation was made in the same manner as the red pigment dispersion paste so that the composition was as follows.

Blue pigment: CIPigment Blue 15: 6 40 parts by weight Dispersant: 10 parts by weight of DisperByk-111 manufactured by Big Chemie Corporation Solvent: 50 parts by weight of 2- (2-butoxyethoxy) ethyl acetate
(B) Preparation of coloring composition The coloring composition was prepared using the thermosetting resin which has various melt indexes and a glass transition point of 80 degreeC.

[Synthesis of thermosetting resin]
Synthesis example 1
Add 1388 g (15 mol) of epichlorohydrin and 342 g (1.5 mol) of bisphenol A to a 3 liter four-necked flask equipped with a thermometer, stirrer, dropping funnel and apparatus for concentrating the azeotropic mixture of epichlorohydrin and water. . While stirring, the mixture is heated to 120 ° C. and refluxed, and 304 g of 40% aqueous caustic soda is added to this over 3.5 hours. After completion of the dropwise addition, the mixture is further heated for 15 minutes to completely distill off water, and then unreacted epichlorohydrin is distilled off.

  After adding 60 g of toluene to the crude product and dissolving it, the sodium chloride was removed by filtration, and then heated to 180 ° C. to completely remove the toluene.

  The obtained resin had an MI value of 80 g / 10 min and a glass transition point by the TMA method of 152 ° C.

Synthesis example 2
A thermosetting resin was obtained in the same manner as in Synthesis Example 1 except that bisphenol A was changed to 456 g (2 mol) in Synthesis Example 1. The obtained resin had an MI value of 40 g / 10 min and a glass transition point by TMA method of 165 ° C.

Synthesis example 3
A thermosetting resin was obtained in the same manner as in Synthesis Example 1 except that bisphenol A was changed to 684 g (3 mol) in Synthesis Example 1. The obtained resin had an MI value of 25 g / 10 min and a glass transition point by the TMA method of 182 ° C.

Synthesis example 4
A thermosetting resin was obtained in the same manner as in Synthesis Example 1 except that bisphenol A was changed to 228 g (1 mol) in Synthesis Example 1. The obtained resin had an MI value of 110 g / 10 min and a glass transition point by the TMA method of 145 ° C.

Synthesis example 5
A thermosetting resin was obtained in the same manner as in Synthesis Example 1 except that bisphenol A was changed to 1140 g (5 mol) in Synthesis Example 1. The obtained resin had an MI value of 15 g / 10 min and a glass transition point by the TMA method of 210 ° C.

Example 1
To 100 g of the pigment dispersion paste of each color prepared in (A), 50 g of the thermosetting resin prepared in Synthesis Example 1 and 240 g of 2- (2-butoxyethoxy) ethyl acetate are well stirred to prepare a colored composition of each color. did.

Example 2
A colored composition of each color was prepared in the same manner as in Example 1 except that the thermosetting resin produced in Synthesis Example 1 in Example 1 was changed to the thermosetting resin produced in Synthesis Example 2.

Example 3
A colored composition of each color was prepared in the same manner as in Example 1 except that the thermosetting resin produced in Synthesis Example 1 in Example 1 was changed to the thermosetting resin produced in Synthesis Example 3.

Comparative Example 1
A colored composition of each color was prepared in the same manner as in Example 1 except that the thermosetting resin produced in Synthesis Example 1 in Example 1 was changed to the thermosetting resin produced in Synthesis Example 4.

Comparative Example 2
A colored composition of each color was prepared in the same manner as in Example 1, except that the thermosetting resin produced in Synthesis Example 1 in Example 1 was changed to the thermosetting resin produced in Synthesis Example 5.

Comparative Example 3
A colored composition of each color was prepared in the same manner as in Example 1 except that 50 g of the thermosetting resin prepared in Synthesis Example 1 was changed to 25 g in Example 1.

The melt index values and glass transition points of the thermosetting resins used in the examples and comparative examples are shown in Table 1 below. In addition, Table 2 below shows the results of smoothness of the R, G, and B colored layers of the produced color filter substrate.

Sectional drawing which shows the manufacturing process of the color filter which concerns on one Embodiment of this invention in process order.

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 (3)

A step of forming a light-shielding layer having a predetermined pattern on a transparent substrate, and a colored composition of each color is ejected into an opening of the light-shielding layer so as to have a predetermined arrangement by an inkjet method, thereby forming a plurality of colored layers. The coloring composition contains a pigment and a thermosetting resin, and a melt index (JISK7210; test temperature 125 ° C., test load 2.16 kgf) of the thermosetting resin is 20 g to 100 g / 10. a minute, 120 ° C. to 200 DEG ° C. der glass transition point is, the solid content ratio of pigment to the thermosetting resin in the colored composition 1 in weight ratio: being a 2: 4-3 A method for producing a color filter. Claim; (test temperature 125 ° C., test load 2.16 kgf JIS K7210) is 30~90g / 10 minutes, wherein the glass transition point of 0.99 ° C. to 180 ° C. The melt index of the thermosetting resin The manufacturing method of the color filter of 1 . The method for producing a color filter according to claim 1, wherein the light shielding layer contains a water repellent.

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