JP2006284674A - Color filter - Google Patents

Abstract

【Task】
An object of the present invention is to form an ideal quadrangular shape in a color filter used in a liquid crystal display device such as a television without causing deformation of a partition wall that separates pixels of each color due to heat sag of a thermosetting resin. Or it is to make it a reverse taper shape, Furthermore, it is providing the color filter in which the coloring composition in each pixel does not have flat color unevenness.
[Solution]
A binder resin, a compound having cationic polymerizability, a cation generator, and a dehydrating agent are used in the resin composition used for the partition wall, thereby enhancing the effectiveness of the cation generator. As a result, the cross-linking reaction between the binder resin and the compound having cationic polymerizability is promoted, the colored composition in each pixel formed by inkjet becomes flat, and a high-definition color filter having good characteristics without color unevenness is obtained. Can do.
[Selection] Figure 1

Description

  The present invention relates to a color filter used for a liquid crystal display device or the like. More specifically, the present invention relates to a color filter in which each pixel is printed by an ink jet method and has a flat and uniform colored layer on each pixel.

  A color filter used in a color liquid crystal display device or the like is an indispensable member for a color liquid crystal display device or the like, and has a role of improving the image quality of the liquid crystal display device or giving each pixel a color of each primary color. Yes. Various studies have been made on the manufacturing method of this color filter, and a photolithography method, an ink jet method, and the like are known as typical methods. In the photolithography method, a coating film of a photosensitive resin layer of each color is formed on the entire substrate, and unnecessary portions of the coating film are removed later, and the remaining pattern is used as each color pixel. In this method, many of the coating films are unnecessary, and a large amount of materials such as pigments are wasted when manufacturing the color filter. Further, since the exposure and development processes are performed for each color pixel, the number of processes increases. For this reason, the production of color filters by the photolithography method has problems in both cost and environment. In particular, in recent years, the size of liquid crystal display devices has been increasing, and accordingly, the color filter substrate is also increased in size, resulting in a further waste of materials. In recent years, an ink jet method has attracted attention as a method for producing a color filter that overcomes this problem. The production of the color filter by the ink jet method can be performed at a time because the photosensitive resin composition of three colors of R, G, and B is used as ink and each color is printed simultaneously. For this reason, almost no waste of materials such as pigments occurs, and the formation process of the three-color pixels is shortened at the same time, so that it is possible to expect a reduction in environmental load and a significant cost reduction.

  As a method for manufacturing a color filter substrate using an inkjet method, methods described in Patent Documents 1 to 5 have been proposed. In Patent Document 1, in order to prevent the ink from spreading outside a desired colored layer region on a glass substrate, a pattern is obtained by adding a hydrofluoric acid-based water / oil repellent to a black partition wall that partitions each pixel in advance. It is described that the ink is fixed only in the colored region by forming. Patent Documents 2 and 3 describe that a black resin layer containing a fluorine-containing compound and / or a silicon-containing compound is used as a partition wall for bleeding in ink in the colored layer forming step and preventing color mixing. Has been. Patent Document 4 discloses a manufacturing method that includes a substrate processing step of eliminating the water and oil repellency after forming the partition wall and the pixel of each pixel so that any surface has water and oil repellency. Are listed.

  However, the above-described conventional method has a problem that a colored resin composition (hereinafter referred to as a colored layer) printed by ink jet does not have a flat shape but a convex shape. For this reason, variation occurs in the shape of each pixel of the color filter, a defect called “white spot” occurs in a thin layer portion, and a problem of color unevenness occurs due to a difference in chromaticity. It caused the quality defect of the manufactured color liquid crystal display device. In view of this, a method has been proposed in which the colored layer is flattened by making the partition wall into a quadrangular shape or an inversely tapered shape (Patent Documents 5 and 6). However, the conventional partition including the thermosetting resin has a phenomenon in which corners are rounded (hereinafter referred to as heat sagging) in the thermosetting process (about 150 ° C. to 250 ° C.). This thermal sag appears more prominently when the temperature of the thermosetting process is high or when the thickness of the partition wall is large. On the other hand, when the partition wall was baked at a low temperature of less than 150 ° C., the resin in the partition wall could not be sufficiently cured, causing a problem that the resin in the partition wall was dissolved in the inkjet color ink.

Patent Documents 5 and 6 do not disclose a solution to this problem. For this reason, in a color filter manufactured by an ink jet method, a rectangular or inversely tapered shape without causing problems of thermal sagging and dissolution. It was still difficult to obtain the partition wall.
JP-A-6-347637 JP-A-7-35915 JP 7-35917 A JP-A-7-248413 Japanese Patent Laid-Open No. 2002-62422 Japanese Patent Laid-Open No. 2004-245972

  The present invention was made in order to solve the above-mentioned problems, and the problem is that in the method for producing a color filter by an ink jet method, deformation due to thermal sag of a thermosetting resin does not occur, It is an object to provide an ideal quadrangular or inversely tapered partition wall, thereby providing a method for producing a color filter in which the colored composition in each pixel is flat and free from uneven color.

  By the way, according to the study of the present inventor, when a binder resin and a filler component are added to the resin composition used for forming the partition wall, the matrix polymer in the resin composition is used due to the effect of the filler. It was found that the movement of the arm was constrained and became rigid, so that no thermal sagging occurred. However, since the filler is agglomerated largely in the particle size of the partition wall, the dispersion of the filler inside the partition wall becomes non-uniform, causing a problem of reducing the light shielding effect when the light shielding property is imparted to the partition wall, In addition, a problem such as a jaggedness as shown in FIG. 3 occurred in the partition wall and the pattern shape and linearity deteriorated. Accordingly, it has been found that when a dispersing agent that uniformly disperses the filler in the resin composition system is added at the same time as the filler, the filler is uniformly dispersed and the above problem is solved.

  Moreover, when the partition part with a film thickness of 1.5 μm or more was formed by the manufacturing method of the present invention, the partition part did not generate thermal sag and became a square or reverse tapered shape. And when a colored layer was printed on the color filter which has a partition part with a film thickness of 1.5 micrometers or more by the inkjet system, it was found that a flat colored layer was obtained.

  The present invention has been made on the basis of such knowledge, and the invention according to claim 1 is a color filter in which a colored layer is formed by printing an ink-jet method in pixels partitioned by a partition. The partition wall is made of a resin composition containing at least a binder resin, a filler, and a dispersant.

The invention according to claim 2 is a color filter formed by printing a colored layer by an ink jet method in a pixel delimited by a partition.
The color filter is characterized in that the partition wall is made of a resin composition containing at least a binder resin, a compound having a cationic polymerization property, a cation generator, a filler having a dehydrating property, and a dispersant.

  A third aspect of the present invention is the color filter according to the first or second aspect, wherein a part or all of the partition walls are black.

  Invention of Claim 4 is a color filter in any one of Claims 1-3 in which the said resin composition contains a fluorine-containing compound.

  Invention of Claim 5 is a manufacturing method of the color filter in any one of Claims 1-4 with which the said resin composition contains a silicon-containing compound.

According to a sixth aspect of the present invention, in the color filter formed by printing a colored layer by an inkjet method in the pixels delimited by the partition walls,
The partition wall is made of a resin composition containing at least a binder resin, a filler, and a dispersant,
The partition wall has a square or reverse tapered shape,
The color filter is characterized in that a height of the partition wall is 1.5 μm or more.

  According to the present invention, the filler aggregate is appropriately dispersed so that it can be used for forming the partition wall, and the dispersed filler is used for forming the partition wall. A tapered partition wall could be obtained. For this reason, the coloring composition in each pixel formed by inkjet became flat, and a high-definition color filter having good characteristics without color unevenness could be obtained.

  Further, according to the present invention, even when the film thickness is 1.5 μm or more, no thermal sagging is generated, and a square or reverse tapered partition wall portion can be formed. For this reason, compared with the color filter having a partition wall having a thickness of less than 1.5 μm, the effect of preventing color mixing was further enhanced. For this reason, it was possible to obtain a high-definition color filter that includes a flat colored layer and does not cause color unevenness and color mixing.

  As shown in FIG. 1, a color filter manufactured by forming a colored layer by an ink jet method is provided on a transparent substrate 1 to prevent color mixing of red (R), green (G), and blue (B) colored inks. A partition wall is provided. Further, in order to improve the contrast of the color filter, it is desirable to provide light shielding properties to a part or all of the partition wall 2. In general, as a means for imparting light-shielding properties, a black material is used for a part or all of the partition wall and a black part is provided. In the following description, part or all of the partition walls are referred to as “black matrix” for the sake of convenience. However, the black matrix does not necessarily have a black portion. Next, when a red (R), green (G), and blue (B) colored layer is formed on a transparent substrate, and this is used for liquid crystal, a transparent conductive layer and an alignment film layer are sequentially laminated. For example, a liquid crystal display device is configured through a liquid crystal layer facing a counter substrate on which an electrode such as a thin film transistor is formed. Hereinafter, the transparent substrate, the black matrix, and the red, green, and blue colored pixel layers are combined to form a color filter. A protective layer can be provided on the color filter as necessary.

  As described above, the colored layer is provided in the opening between the black matrices, and the pixel pattern composed of the three primary colors, usually the red pixel pattern (R), the green pixel pattern (G), and the blue pixel pattern (B), has a desired shape. Is arranged. Examples of the general forming method include a pigment dispersion method, a dye method, an electrodeposition method, a printing method, a transfer method, and an ink jet method. In the present invention, the colored resin composition is patterned by an ink jet apparatus, and then the colored layer 3 is formed through a heating process described later.

  For the transparent substrate 1 of the color filter, a known transparent substrate material such as a glass substrate, a quartz substrate, or a plastic substrate can be used. Among them, the glass substrate is excellent in transparency, strength, heat resistance, and weather resistance.

  The colored resin composition used for the colored layer 3 of the color filter can use a known material such as a colorant, a thermosetting resin, or a solvent, and is prepared by adding an additive such as a dispersant as necessary. be able to.

Hereinafter, the formation of the black matrix will be described in detail. The black matrix can be patterned by either a printing method or a photolithography method (hereinafter referred to as a photo method). When a black matrix is formed by a printing method, a black matrix pattern can be printed using a printing material containing a binder resin, a filler, and a dispersant. When a black matrix is formed by a photolithography method, there are a case where a negative photosensitive resin composition is used and a case where a positive photosensitive resin composition is used. In the case of the former negative type, a negative photosensitive resin material containing a binder resin, a filler, a dispersant, a radically polymerizable compound, and a photopolymerization initiator is applied on the substrate 1, and is exposed and patterned using a mask. Thus, a black matrix pattern can be formed. A negative photosensitive resin becomes a reverse taper shape after exposure and development. In the case of the latter positive type, a positive type photosensitive resin material containing a binder resin, a photosensitive agent, a filler, and a dispersing agent is applied on the substrate 1 and exposed and patterned using a mask to form a black matrix pattern. Can be formed. The positive photosensitive resin also has a reverse taper shape after exposure and development as in the negative type. In both positive and negative types, in addition to the above components, a compound having a cationic polymerizability and a cation generator are added to the photosensitive resin material in order to improve the chemical resistance and heat resistance of the black matrix. The binder resin and the compound having cationic polymerizability can be cross-linked by a thermal process. In this case, in order to enhance the action of the cation generator, it is more preferable to use a dehydrating material for the filler.
The present invention is characterized in that it includes a binder resin, a filler, and a dispersant, regardless of whether the black matrix is formed by a printing method or a photo method (positive type or negative type). Further, in order to impart light shielding properties to part or all of the black matrix, a black shielding member can be included in the material of the portion having light shielding properties (hereinafter referred to as a light shielding layer). In order to prevent color mixing and color unevenness of the colored ink, it is preferable to apply an ink repellent agent to a part or all of the black matrix.

  The black matrix is patterned by the printing method or the photo method. Thereafter, by baking at a temperature of 150 to 250 ° C., a square or inversely tapered black matrix can be obtained. When the black matrix is thermally cured at 250 ° C. or higher, the black matrix becomes a bowl-like shape, and a square or reverse tapered black matrix cannot be obtained. On the other hand, when the black matrix is baked at less than 150 ° C., the black matrix resin is dissolved in the colored ink discharged from the inkjet. The firing time is preferably 5 minutes to 60 minutes.

  The black matrix is preferably formed with a height of 1.5 μm or more. More preferably, the height is 2 to 5 μm. When the height of the black matrix is 1.5 μm or less, color mixture of colored inks occurs. On the other hand, if the height of the black matrix is too high, thermal sagging becomes significant and the black matrix becomes a bowl-like shape, and a square or inversely tapered black matrix cannot be obtained.

  The black matrix can have a single layer or a multilayer structure of two or more layers. Generally, there is a limit to the height of a black matrix that can be formed in a single process. Therefore, when forming a black matrix with a large layer thickness, a black matrix having the same pattern is stacked to form a multilayer structure. In the case of forming a one-layer black matrix, it can be formed by using a printing method or a photo method. In this case, the entire black matrix can be provided with a light-shielding property to form a single light-shielding layer. When the black matrix has a multilayer structure, it is preferable that at least one of the layers is provided with a light shielding property to form a light shielding layer. Hereinafter, an example in which the lowermost layer is a light-shielding layer and the upper part thereof is a non-light-shielding layer in the method for producing a multilayered black matrix will be described, but the present invention is not limited to this configuration.

  First, a light shielding layer is formed on the transparent substrate 1. The light shielding layer can be formed by a printing method using the printing material described above or a photo method using a photosensitive resin material, but can also be formed by other known methods. For example, a method of forming a thin film of metal or metal oxide on a substrate or a non-light-shielding layer by a method such as sputtering, and patterning it by a technique such as etching can be used.

  On the light-shielding layer formed on the transparent substrate, a non-light-shielding layer patterned according to the light-shielding layer pattern is further laminated by a photo method or a printing method as many times as necessary. By forming a higher partition wall on the light-shielding layer, the colored ink discharged by the ink jet method can be sufficiently received in the opening between the partition walls, and at the same time, the effect of preventing color mixing due to the ink is obtained. It is done. When the photo method is used, even if a defect occurs when the light shielding layer is formed, the patterned photosensitive resin repairs the defect and functions as a partition wall that separates the pixels. For this reason, ink color mixing due to a defect in the light shielding layer can be prevented. In addition, when a non-light-shielding layer is formed by a photolithography method using a positive photosensitive resin material, the light-shielding layer previously formed on the substrate serves as a mask and back exposure can be performed, so there is no need to prepare a special mask. A non-light-shielding layer can be laminated easily and cost-effectively.

  After a non-light-shielding layer having the same pattern is formed on the light-shielding layer, the multilayer structure is fired and cured under conditions of 150 ° C. to 250 ° C. to obtain a black matrix. Thereafter, three color inks are printed by a known ink jet method, and the color ink is baked to obtain a color filter.

  The above is an example in which the black matrix has a multilayer structure, and the non-light-shielding layer is laminated on the light-shielding layer on the transparent substrate, but the present invention is not limited to this, and the black matrix of other forms The effect of the present invention can be obtained by using the predetermined material and performing firing under the predetermined condition.

  Hereinafter, components and materials included in the printing material and the photosensitive resin material used for forming the black matrix will be described in detail.

  The binder resin of the present invention is thermally cured by heating. Further, when the resin composition also contains a compound having a cationic polymerization property and a cation generator, the resin composition is sufficiently crosslinked with the cationic polymerization compound to impart solvent resistance and heat resistance to the black matrix. is there. The binder resin is not particularly limited as long as it can undergo a crosslinking reaction with a compound having cationic polymerization properties, and includes an amino group, an amide group, a carboxylic acid group, a carboxyl group, a hydroxyl group, an isocyanate group, a urethane group, a mercaptan group, and an acid anhydride. It is even better if it contains a resin. Specific examples include cresol-novolak resins, polyvinyl phenol resins, acrylic resins, methacrylic resins, and the like. These binder resins may be used alone or in combination of two or more.

The compound having cationic polymerizability is sufficiently crosslinked with the binder resin by the action of the cation generator to impart solvent resistance and heat resistance to the black matrix. Examples of the compound having cationic polymerizability include an epoxy compound, a cyclic ether compound, a cyclic lactone compound, a cyclic acetal compound, a cyclic thioether compound, a spiro orthoester compound, and a vinyl compound. In order to further improve heat resistance, it is preferable to use a compound having a polyfunctional epoxy group, a polyfunctional epoxy resin that is a glycidyl etherified product of a polyphenol compound, a polyfunctional epoxy resin that is a glycidyl etherified product of various novolak resins, Alicyclic polyfunctional epoxy resin, aliphatic polyfunctional epoxy resin, heterocyclic polyfunctional epoxy resin, glycidyl ester polyfunctional epoxy resin, glycidylamine polyfunctional epoxy resin, polyfunctionalized glycidylated halogenated phenols An epoxy resin etc. are mentioned as an example. These compounds having cationic polymerizability may be used alone or in admixture of two or more.

  The amount of the compound having cationic polymerizability can be in the range of 1 to 200 parts by weight, preferably 5 to 30 parts by weight, with respect to 100 parts by weight of the binder resin. If the amount is less than 1 part by weight, there will be a problem that the resin in the partition wall dissolves in the ink-jet color ink. If the amount exceeds 200 parts by weight, development cannot be performed when the photo method is used. Occurs.

  The cation generator generates cations by heating or exposure, and accelerates the crosslinking reaction between the binder resin and the compound having cationic polymerizability. Examples of compounds that generate cations by heat include onium salts such as sulfonium salts, benzothiazonium salts, ammonium salts, and phosphonium salts. Examples of the compound that generates a cation upon exposure include diaryliodonium salts and triarylsulfonium salts. Two or more of the above cation generators may be used in combination, or a compound that generates cations by heat and a compound that generates cations by exposure may be used in combination. Specific examples of the cation generator include diphenyliodonium, ditolyliodonium, phenyl (4-anisyl) iodonium, bis (3-nitrophenyl) iodonium, bis (4-tert-butylphenyl) iodonium, bis (4 -Chlorophenyl) iodonium, bis (4-n-dodecylphenyl) iodonium, 4-isobutylphenyl (4-tolyl) iodonium, diaryliodonium such as 4-isopyrphenyl (4-tolyl) iodonium, or triaryl such as triphenylsulfonium Triarylsulfonium chloride, bromide, borofluoride, hexafluorophosphate salt, hexafluoroarsenate salt, aromatic sulfonate salt, tetrakis (pentaful) such as reelsulfonium Rophenyl) borate salts, sulfonium organic boron complex salts such as diphenylphenacylsulfonium (n-butyl) triphenylborate, 2-methyl-4,6-bistrichloromethyltriazine, 2- (4-methoxyphenyl) -4 , 6-bistrichloromethyltriazine, triazine compounds such as 2- {2- (5-methylfuran-2-yl) ethenyl} -4,6-bis (trichloromethyl) -s-triazine, or 1,2-naphthoquinonediazide, 1,2-Naphthoquinonediazido 4-sulfonsan sodium, 1,2-naphthoquinone diazide 5-sodium sulfonate, 1,2-naphthoquinone diazide 4-sulfonic acid ester derivative, 1,2-naphthoquinone diazide 5-sulfone Diazo such as acid ester derivatives Futokinon compounds, and the like can be mentioned.

  The addition amount of the cation generator can be in the range of 0.1 to 25 parts by weight, preferably 1 to 20 parts by weight with respect to 100 parts by weight of the binder resin. When the amount is 25 parts by weight or more, there is a problem in storage stability.

  The filler prevents heat sag of the resin composition. An inorganic filler etc. can be used as an example of a filler. Moreover, when a compound having a cationic polymerization property and a cation generator are added to the resin composition, it is preferable to impart dehydrating properties to the filler. Examples of such fillers include calcium carbonate, talc, kaolin, clay, and silica. , Mica, wollastonite, potassium titanate, zonolite, basic magnesium sulfate, tetrapotted zinc oxide, and aluminum folate. The filler preferably has an average primary particle size in the range of 1 to 500 nm, more preferably 50 to 500 nm. Moreover, these fillers may be used independently or may mix 2 or more types. These may be treated with various surface treatment agents.

  As a ratio of the filler with respect to binder resin, it is 5-1000 weight part with respect to 100 weight part of binder resin. When the amount was 5 parts by weight or less, the thermal sag of the resin could not be suppressed, and when the amount was 50 parts by weight or more, filler aggregation occurred.

  The dispersant is for dispersing the filler in the resin composition and smoothing the surface of the black matrix. Examples of the dispersant of the present invention include a nonionic surfactant such as polyoxyethylene alkyl ether, and an ionic surfactant such as sodium alkylbenzene sulfonate, poly fatty acid salt, and fatty acid salt alkyl. In addition to phosphates, tetraalkylammonium salts, and the like, organic pigment derivatives, polyesters, and the like can be given. One type of dispersant may be used alone, or two or more types of dispersants may be mixed and used.

The ratio of the dispersant to the filler is 5 to 50 parts by weight with respect to 100 parts by weight of the filler. When the amount is 5 parts by weight or less, the filler aggregates. On the other hand, when the amount is 50 parts by weight or more, problems such as development failure occur.

The dispersant in the present invention is preferably dispersed in advance. As a dispersion method, the binder resin is mixed with a solvent such as toluene, xylene, cyclohexanone, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, diethylene glycol dimethyl ether to form a solution, and a finely dispersed hygroscopic agent is added thereto, A method of mixing with a mixing device such as a homogenizer to form a dispersion, a method of removing the solvent from the dispersion and then finely pulverizing it into a fine powder, and various types containing a reactive group with a binder resin as a dispersant A method can be employed in which a surfactant is added to a hygroscopic agent, and this is sufficiently kneaded with a stirrer such as a binder resin and a roll, dried, and then finely pulverized into a fine powder. It is not limited to these.

  As the compound having radical polymerizability, for example, a monomer or oligomer having a vinyl group or an allyl group, or a polymer having a vinyl group or an allyl group at the terminal or side chain can be used. Specifically, (meth) acrylic acid and salts thereof, (meth) acrylic acid esters, (meth) acrylamides, maleic anhydride, maleic acid esters, itaconic acid esters, styrenes, vinyl ethers, vinyl esters, N -Vinyl heterocycles, allyl ethers, allyl esters, and derivatives thereof. Suitable compounds include, for example, relatively low molecular weight polyfunctional acrylates such as pentaerythritol triacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, and hexaacrylate. Yes, but not this. These radically polymerizable compounds may be used alone or in combination of two or more. The amount of the compound having radical polymerizability can be in the range of 1 to 200 parts by weight, preferably 50 to 150 parts by weight with respect to 100 parts by weight of the binder resin.

  The photopolymerization initiator generates radicals by exposure and crosslinks the binder resin through a compound having radical polymerizability. Specific examples of photopolymerization initiators include benzophenone compounds such as benzophenone, 4,4′-bis (dimethylamino) benzophenone, 4,4′-bis (diethylamino) benzophenone, 1-hydroxycyclohexylacetophenone, 2,2 Acetophenone derivatives such as 2-dimethoxy-2-phenylacetophenone and 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, thioxanthone, 2,4-diethylthioxanthone, 2-isopropyl Thioxanthone derivatives such as thioxanthone and 2-chlorothioxanthone, anthraquinone derivatives such as 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone and chloroanthraquinone, benzoin methyl ether, benzoy Benzoin ether derivatives such as ethyl ether and benzoin phenyl ether, acylphosphine derivatives such as phenylbis- (2,4,6-trimethylbenzoyl) -phosphine oxide, 2- (o-chlorophenyl) -4,5-bis ( 4'-methylphenyl) imidazoline dimer and other lophine mers, N-arylglycines such as N-phenylglycine, organic azides such as 4,4'-diazidochalcone, 3,3 ', 4,4 Examples include '-tetra (tert-butylperoxycarboxy) benzophenone and quinonediazide group-containing compounds. These photopolymerization initiators may be used alone or in combination of two or more. The quantity of a photoinitiator can take the range of 0.1-50 weight part with respect to 100 weight part of binder resin, Preferably it is 1-20 weight part.

  The printing material or photosensitive resin material used for forming the black matrix can be diluted with an appropriate solvent as necessary. The solvent is dried after printing or coating on the substrate. Specific examples of the solvent include dichloromethane, dichloroethane, chloroform, acetone, cyclohexanone, ethyl acetate, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 2-ethylethoxyacetate, 2-butoxyethyl acetate, 2-methoxyethyl ether, 2-ethoxyethyl ether, 2- (2-ethoxyethoxy) ethanol, 2- (2-butoxyethoxy) ethanol, 2- (2′ethoxyethoxy) ethyl acetate, 2- (2-butoxyethoxy) ) Ethyl acetate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, diethylene glycol dimethyl ether, tetrahydrofuran and the like can be used. The amount of the solvent used is desirably a coating that is uniform when printed or coated on a substrate, and can form a coating film without pinholes and uneven coating. As the content ratio of such a solvent, it is preferable to prepare so that the amount of the solvent is 50 to 97% by weight based on the total weight of the printing material or the photosensitive resin material.

  The black light blocking member imparts light blocking properties to the black matrix and improves the contrast of the color filter. As the black light shielding member, black pigment, black dye, carbon black, aniline black, graphite, iron black, titanium oxide, inorganic pigment, and organic pigment can be used. These black light shielding members may be used alone or in combination of two or more.

  The ink repellent agent imparts ink repellency to the black ink on the black matrix. The ink repellent agent can be added in advance to a printing material or a photosensitive resin material used for forming the black matrix. As the ink repellent agent, a fluorine-containing compound or a silicon-containing compound can be used, and it is more preferable to use a mixture thereof. Specific examples of the fluorine-containing compound include vinylidene fluoride, vinyl fluoride, ethylene trifluoride and the like, and fluororesins such as copolymers thereof. These fluorine-containing compounds can be used alone or in combination of two or more. Examples of the silicon-containing compound include organic silicon in a main chain or a side chain, and examples thereof include a silicon resin containing a siloxane component and silicone rubber. These silicon-containing compounds can be used alone or in combination of two or more. Further, the fluorine-containing compound and the silicon-containing compound, or other ink repellent components may be used in combination. The amount of the fluorine-containing compound or silicon-containing compound contained in the printing material or photosensitive resin material in the present invention is preferably 0.01% by weight to 10% by weight with respect to the total part by weight.

  In addition, for printing materials or photosensitive resin materials used for forming the black matrix, compatible additives as required, such as leveling agents, chain transfer agents, stabilizers, sensitizing dyes, surfactants, couplings. An agent or the like can be added.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example and a comparative example, this invention is not limited to this form.

<Example 1>
(Create black matrix)
As the transparent substrate, alkali-free glass (“# 1737” manufactured by Corning) was used. On this transparent substrate, a photosensitive resin composition having the following composition ratio was sufficiently kneaded with three rollers and then applied to a thickness of 2.0 μm.
[Photosensitive resin composition A]
Cresol-novolak resin "EP4050G" (Asahi Organic Materials Co., Ltd.) 100 parts by weight filler "Snowtex ZL" (Nissan Chemical Co., Ltd.) 30 parts by weight radically polymerizable compound "Pentaerythritol Reacrylate" (Osaka Organics Co., Ltd.)
80 parts by weight photopolymerization initiator “Irgacure 369” (manufactured by Ciba Specialty Chemicals) 1 part by weight cyclohexanone 400 parts by weight carbon pigment “MA-8” (manufactured by Mitsubishi Materials) 78 parts by weight dispersant “Solsperse # 5000” (Zeneca Corporation) 4.7 parts by weight of fluorine-containing compound “F179” (Dainippon Ink Chemical Co., Ltd.) 22 parts by weight

Thereafter, the transparent substrate was pre-baked, and thereafter, using a photomask having a lattice pattern, 100 mJ / cm 2 exposure was performed with an ultrahigh pressure mercury lamp, and development processing was performed. Subsequently, the transparent substrate was oven-heated at 230 ° C. for 30 minutes (Example 1 shown in Table 1).
In order to confirm the shape of the produced black matrix, the cross section was confirmed with a scanning electron microscope. As a result, the black matrix produced in Example 1 had an inversely tapered shape. The surface was flat and the surface roughness measured was 50 mm.
Subsequently, when the OD value (optical density) of the black matrix was measured, it was 6, and it was confirmed that any of them could be used as a light-shielding layer because it had sufficient light-shielding properties.

The definition of the OD value is shown below. When visible light is transmitted through a 1 μm sample, the incident light intensity is I0, and the transmitted light intensity is I.
OD value = -log (I / I0)

  Further, when colored ink was printed on the substrate having the black matrix using an ink jet apparatus, the black matrix produced in Example 1 was not dissolved in the colored ink. Further, when the contact angle between the side surface of the black matrix prepared in Example 1 and the colored ink was measured, both were about 30 °, and it was confirmed that there was further ink repellency with respect to the colored ink.

<Comparative Example 1>
A photosensitive resin composition B having exactly the same composition as that of the photosensitive resin composition A of Example 1 was prepared except that the filler “Snowtex ZL” (manufactured by Nissan Chemical Industries, Ltd.) was not used. A color filter having a black matrix was produced in the process.
(Create black matrix)
In order to confirm the shape of the produced black matrix, the cross-section was confirmed with a scanning electron microscope. As a result, the black matrix produced in Comparative Example 1 generated a heat sagging and became a rounded bowl-like shape. The results are shown in Table 1.
Subsequently, when the OD value (optical density) of the black matrix was measured, it was 6, and since it had sufficient light-shielding properties, it was confirmed that any of them could be used as a light-shielding layer.
Further, when a colored ink was printed on the substrate having the black matrix by using an ink jet apparatus, the black matrix prepared in Comparative Example 1 was not dissolved in the colored ink.

<Comparative example 2>
A photosensitive resin composition C having exactly the same composition as that of the photosensitive resin composition A of Example 1 was prepared except that the dispersant “Solsperth # 5000” (manufactured by Zeneca) was not used. A color filter having a black matrix was produced in the process.
(Create black matrix)
In order to confirm the shape of the produced black matrix, the cross section was confirmed with a scanning electron microscope. As a result, the black matrix produced in Comparative Example 2 maintained an inversely tapered shape as a whole, but the surface was rough. The surface roughness was 500 mm. The results are shown in Table 1.
The black matrix prepared in Comparative Example 2 could not be used as a black matrix because of its large surface roughness. Moreover, it was 5 when OD value (optical density) was measured.

<Comparative Example 3>
Photosensitive resin having exactly the same composition as the photosensitive resin composition A of Example 1 except that the dispersant “Solsperth # 5000” (manufactured by Zeneca) and filler “Snowtex ZL” (manufactured by Nissan Chemical Industries) are not used. Composition C was prepared, and a color filter having a black matrix was prepared in the same process as in Example 1.
(Create black matrix)
In order to confirm the shape of the produced black matrix, the cross-section was confirmed with a scanning electron microscope. As a result, the black matrix produced in Comparative Example 3 generated a thermal sagging and became a rounded bowl-like shape. The results are shown in Table 1.

<Example 2>
A black matrix was formed by the same process as in Example 1 except that the photosensitive resin composition A of Example 1 was formed to a thickness of 1 μm.
In order to confirm the shape of the produced black matrix, the cross section was confirmed with a scanning electron microscope. As a result, the black matrix produced in Example 2 had an inversely tapered shape. The surface was flat and the surface roughness measured was 50 mm.
Subsequently, when the OD value (optical density) of the black matrix was measured, it was 3, and since it had sufficient light-shielding properties, it was confirmed that any of them could be used as a light-shielding layer.
Further, when colored ink was printed on the substrate having the black matrix by using an ink jet apparatus, the black matrix produced in Example 2 was not dissolved in the colored ink. Further, when the contact angle between the side surface of the black matrix prepared in Example 2 and the colored ink was measured, both were about 30 °, and it was confirmed that there was further ink repellency with respect to the colored ink.

<Examples 3 to 7>
A photosensitive resin composition I having the following composition ratio was placed on the black matrix (film thickness 1 μm) prepared in Example 2 at 0.5 μm, 1.0 μm, 2.0 μm, 3.0 μm, 4.0 μm. It was applied to the film thickness.
[Photosensitive resin composition I]
Cresol-novolak resin "EP4050G" (Asahi Organic Materials Co., Ltd.) 100 parts by weight filler "Snowtex ZL" (Nissan Chemical Co., Ltd.) 30 parts by weight radically polymerizable compound "Pentaerythritol Reacrylate" (Osaka Organics Co., Ltd.)
80 parts by weight photopolymerization initiator “Irgacure 369” (manufactured by Ciba Specialty Chemicals) 1 part by weight cyclohexanone 400 parts by weight dispersant “Solsperth # 5000” (manufactured by Zeneca) 4.7 parts by weight fluorine-containing compound “F179” (Dainippon) 22 parts by weight)

Thereafter, the transparent substrate was pre-baked and then exposed to 100 mJ / cm 2 with an ultrahigh pressure mercury lamp using a photomask having a lattice pattern. Thereafter, development processing was performed. Under the present circumstances, the black matrix (Examples 3-7) which carried out oven heating for 30 minutes with the post-baking temperature of 230 degreeC was produced. Table 2 shows the shapes of these black matrices.
When the cross section was confirmed with a scanning electron microscope in order to confirm the shape of the produced black matrix, the black matrix produced in Examples 3 to 7 had an inversely tapered shape. Moreover, the surface was flat, and when the surface roughness was measured, all were about 50 mm. The results are shown in Table 2.
Subsequently, when the OD value (optical density) of the black matrix was measured, it was 3, and since it had sufficient light-shielding properties, it was confirmed that any of them could be used as a light-shielding layer.
Moreover, when colored ink was printed on the board | substrate which has this black matrix using the inkjet apparatus, the black matrix produced in Examples 3-7 did not melt | dissolve in colored ink. Furthermore, when the contact angle between the side surface of the black matrix prepared in Examples 3 to 7 and the colored ink was measured, all were about 30 °, and it was confirmed that there was further ink repellency with respect to the colored ink. The results are shown in Table 2.

<Comparative example 4>
A black matrix was formed in the same process as in Comparative Example 1 except that the photosensitive resin composition B of Comparative Example 1 was formed to a thickness of 1 μm.
In order to confirm the shape of the produced black matrix, the cross section was confirmed with a scanning electron microscope. As a result, the black matrix produced in Comparative Example 4 maintained an inversely tapered shape as a whole, but the surface was rough. The surface roughness was 500 mm.
The black matrix prepared in Comparative Example 4 could not be used as a black matrix because of its large surface roughness. Moreover, it was 2 when the OD value (optical density) was measured.

<Comparative Examples 5-9>
A photosensitive resin composition J having the following composition ratio was placed on the black matrix (film thickness 1 μm) produced in Comparative Example 8 at 0.5 μm, 1.0 μm, 2.0 μm, 3.0 μm, 4.0 μm. It was applied to the film thickness.
[Photosensitive resin composition J]
Cresol-novolak resin "EP4050G" (Asahi Organic Materials Co., Ltd.) 100 parts by weight filler "Snowtex ZL" (Nissan Chemical Co., Ltd.) 30 parts by weight radically polymerizable compound "Pentaerythritol Reacrylate" (Osaka Organics Co., Ltd.)
80 parts by weight photopolymerization initiator “Irgacure 369” (manufactured by Ciba Specialty Chemicals) 1 part by weight cyclohexanone 400 parts by weight fluorinated compound “F179” (manufactured by Dainippon Ink & Chemicals) 22 parts by weight

Thereafter, the transparent substrate was pre-baked and then exposed to 100 mJ / cm 2 with an ultrahigh pressure mercury lamp using a photomask having a lattice pattern. Thereafter, development processing was performed. At this time, black matrices (Comparative Examples 5 to 9) that were oven-heated at a post-bake temperature of 230 ° C. for 30 minutes were prepared. Table 2 shows the shapes of these black matrices.
In order to confirm the shape of the produced black matrix, the cross section was confirmed with a scanning electron microscope. As a result, the black matrix produced in Comparative Examples 5 to 9 maintained a reverse tapered shape as a whole, but the surface was rough. The surface roughness was 500 mm. The results are shown in Table 2.
The black matrices prepared in Comparative Examples 5 to 9 could not be used as the black matrix due to the large surface roughness. Moreover, it was 2 when the OD value (optical density) was measured.

<Example 8>
Poly (4-vinylphenol) (manufactured by Maruzen Petrochemical Co., Ltd., product name “Marlinker MS-1”) is used instead of cresol-novolak resin (manufactured by Asahi Organic Materials Co., Ltd., product name “EP4050G”) as a binder resin. A color filter having a black matrix was produced in the same manner as in Example 1 except that.

<Example 9>
Example 1 except that acrylic resin (manufactured by Nippon Steel Chemical Co., product name “V-259”) was used instead of cresol-novolak resin (manufactured by Asahi Organic Materials Co., Ltd., product name “EP4050G”) as the binder resin. Thus, a color filter having a black matrix was produced.

<Example 10>
It has a black matrix in the same manner as in Example 1 except that (the product name “Snowtex ZL” manufactured by Nissan Chemical Industries, Ltd., product name “Softon 3200”) is used instead of (manufactured by Nissan Chemical Co., Ltd., product name “Snowtex ZL”). A color filter was manufactured.

<Example 11>
Except for using (product name “manufactured magnesium carbonate (light))” instead of (manufactured by Nissan Chemical Co., Ltd., product name “Snowtex ZL”) in the same manner as Example 1, A color filter having a black matrix was produced.

<Example 12>
It has a black matrix in the same manner as in Example 1 except that (the product name “Snowtex ZL” manufactured by Nissan Chemical Co., Ltd.) is used as the filler (product name “A-61” manufactured by Yamaguchi Mica Co., Ltd.). A color filter was manufactured.

<Example 13>
A color having a black matrix as in Example 1, except that (Nissan Chemical Co., Ltd., product name “Snowtex ZL”) was used instead of (Nihon Talc, product name “K-1”) as the filler. A filter was manufactured.

<Example 14>
A color having a black matrix in the same manner as in Example 1 except that instead of (manufactured by Nissan Chemical Co., Ltd., product name “Snowtex ZL”) (manufactured by Kyowa Chemical Co., Ltd., product name “Kyowa Mag 150”) was used. A filter was manufactured.

In order to confirm the shape of the black matrix produced in Examples 8-14, when the cross section was confirmed with the scanning electron microscope, the black matrix produced in Examples 8-14 had a reverse taper shape. Moreover, the surface was flat, and when the surface roughness was measured, all were about 50 mm.
Subsequently, when the OD value (optical density) of the black matrix was measured, it was 6, and since it had sufficient light-shielding properties, it was confirmed that any of them could be used as a light-shielding layer.
Moreover, when colored ink was printed on the board | substrate which has this black matrix using the inkjet apparatus, the black matrix produced in Examples 8-14 did not melt | dissolve in colored ink.

(Example 15)
On a transparent substrate, a printing resin composition having the following composition ratio was sufficiently kneaded with three rollers, and then applied to a film thickness of 2.0 μm using a reverse printing method. In the reverse printing, a metal roll having a surface coated with a silicone resin was used as a blanket plate. Moreover, the flat glass which processed the surface into the uneven pattern according to the inversion pattern of the partition pattern was used as a peeling member. The ink composition was applied on the blanket plate using a slit coater to form a uniform ink layer on the blanket plate. Next, an unnecessary portion of the ink layer of the blanket plate was removed by a peeling member, and an inverted pattern of the light shielding layer pattern was formed on the blanket plate. Thereafter, the blanket plate on which the reversal pattern was formed was brought into contact with one main surface of the transparent substrate, the reversal pattern was transferred onto the transparent substrate surface, and a black matrix was formed on the transparent substrate.
[Printing resin composition A]
Cresol-Novolac resin “EP4050G” (Asahi Organic Materials Co., Ltd.) 100 parts by weight filler “Snowtex ZL” (Nissan Chemical Co., Ltd.) 30 parts by weight cyclohexanone 400 parts by weight Carbon pigment “MA-8” (Mitsubishi Materials) 78 Part by weight Dispersant “Solsperse # 5000” (manufactured by Zeneca) 4.7 parts by weight Fluorine-containing compound “F179” (manufactured by Dainippon Ink & Chemicals)

Thereafter, the transparent substrate was oven heated at 230 ° C. for 30 minutes to produce a black matrix. When the cross section was confirmed with a scanning electron microscope in order to confirm the shape of the produced black matrix, the black matrix produced in Example 15 had an inversely tapered shape. The surface was flat and the surface roughness measured was 50 mm.
Subsequently, when the OD value (optical density) of the black matrix was measured, it was 6, and since it had sufficient light-shielding properties, it was confirmed that any of them could be used as a light-shielding layer.
Further, when colored ink was printed on the substrate having the black matrix by using an ink jet apparatus, the black matrix produced in Example 15 was not dissolved in the colored ink. The results are shown in Table 3.

<Comparative Example 10>
A printing resin composition B having exactly the same composition as the printing resin composition A of Example 15 was prepared except that the filler “Snowtex ZL” (manufactured by Nissan Chemical Co., Ltd.) was not used. A color filter having a black matrix was prepared.
(Create black matrix)
In order to confirm the shape of the produced black matrix, the cross-section was confirmed with a scanning electron microscope. As a result, the black matrix produced in Comparative Example 10 generated a thermal sag and became a rounded bowl-like shape. The results are shown in Table 3.
Subsequently, when the OD value (optical density) of the black matrix was measured, it was 6, and since it had sufficient light-shielding properties, it was confirmed that any of them could be used as a light-shielding layer.
In addition, when colored ink was printed on the substrate having the black matrix by using an ink jet apparatus, the black matrix produced in Comparative Example 10 was not dissolved in the colored ink.

<Comparative Example 11>
A printing resin composition C having exactly the same composition as the printing resin composition A of Example 15 was prepared except that the dispersant “Solsperth # 5000” (manufactured by Zeneca) was not used. A color filter having a black matrix was prepared.
(Create black matrix)
In order to confirm the shape of the produced black matrix, the cross section was confirmed with a scanning electron microscope. As a result, the black matrix produced in Comparative Example 11 maintained an inversely tapered shape as a whole, but the surface was rough. The surface roughness was 500 mm. The results are shown in Table 3.
The black matrix prepared in Comparative Example 11 could not be used as a black matrix due to its large surface roughness. Moreover, it was 5 when OD value (optical density) was measured.

<Comparative Example 12>
A printing resin composition having exactly the same composition as the printing resin composition A of Example 15 except that the dispersant “Solsperth # 5000” (manufactured by Zeneca) and filler “Snowtex ZL” (manufactured by Nissan Chemical Industries) are not used. C was prepared, and a color filter having a black matrix was prepared in the same process as in Example 15.
(Create black matrix)
In order to confirm the shape of the produced black matrix, the cross section was confirmed with a scanning electron microscope. As a result, the black matrix produced in Comparative Example 12 was sagted and became a rounded bowl-like shape. The results are shown in Table 3.

Hereinafter, a process of forming a colored ink layer on the color filter including the black matrix created in the above-described embodiment using an inkjet apparatus will be described.
<Creation of a color filter using the black matrix of the present invention>
(Colored ink adjustment)
[Colored ink composition]
Methacrylic acid 20 parts by weight Methyl methacrylate 10 parts by weight Butyl methacrylate 55 parts by weight Hydroxyethyl methacrylate 15 parts by weight Butyl lactate 300 parts by weight

A colored ink composition having the above composition was added with 0.75 parts by weight of azobisisobutylnitrile under a nitrogen atmosphere, and reacted at 70 ° C. for 5 hours to obtain an acrylic copolymer resin. The obtained acrylic copolymer resin was diluted with propylene glycol monomethyl ether acetate so as to be 10% by weight with respect to the whole to obtain a diluted solution of the acrylic copolymer resin.

  Add 19.0 g of color pigment and 0.9 g of polyoxyethylene alkyl ether as a dispersant to 80.1 g of this diluted solution, and knead with three rolls to obtain red, green and blue colored varnishes. It was. As a red pigment, Pigment Red 177, Pigment Green 36 as a green pigment, and Pigment Blue 15 as a blue pigment were used.

  Propylene glycol monomethyl ether acetate is added to each colored varnish so that the pigment concentration is 12 to 15% by weight and the viscosity is 15 cps, and red, green, and blue colored inks are obtained. It was.

  Specific examples of the color pigment added to the color ink composition include Pigment Red 9, 19, 38, 43, 97, 122, 123, 144, 149, 166, 168, 177, 179, 180, 192, 215, 216, 208, 216, 217, 220, 223, 224, 226, 227, 228, 240, Pigment Blue 15, 15: 6, 16, 22, 29, 60, 64, Pigment Green 7, 36, Pigment Red20 24, 86, 93, 108, 109, 110, 117, 125, 137, 138, 139, 147, 148, 153, 154, 166, 168, 185, Pigment Orange 36, Pigment Violet 23, etc. Or 2 It can be used as a mixture of at least.

  As the solvent used in the colored ink composition, a solvent having a surface tension within a range suitable for the ink jet system, for example, 40 mN / m or less and a boiling point of 130 ° C. or more can be preferably used. If the surface tension exceeds 40 mN / m, the dot shape stability during ink jet discharge tends to be significantly adversely affected. If the boiling point is less than 130 ° C., the drying property near the nozzle becomes extremely high. Therefore, there is a tendency to cause defects such as nozzle clogging. Suitable solvents include, for example, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 2-ethoxyethyl acetate, 2-butoxyethyl acetate, 2-methoxyethyl acetate, 2-ethoxyethyl ether, 2- (2- And ethoxyethoxy) ethanol, 2- (2-butoxyethoxy) ethanol, 2- (2-ethoxyethoxy) ethyl acetate, 2- (2-butoxyethoxy) ethyl acetate, 2-phenoxyethanol, and diethylene glycol dimethyl ether. If necessary, they can be used alone or in admixture of two or more. In addition to solubility, the solvent is required to be stable over time, dryness, and the like, and is appropriately selected according to the properties of the colorant and binder resin used.

The above-mentioned colored ink composition can be blended with the following binder resins. Examples of the binder resin for the colored ink composition include casein, gelatin, polyvinyl alcohol, carboxymethyl acetal, polyimide resin, acrylic resin, epoxy resin, and melamine resin, and are appropriately selected according to the colorant used. obtain. For example, acrylic resin is preferable when heat resistance and light resistance are required.
In order to improve the dispersion of the pigment in the binder resin of the colored ink composition, a dispersant can be added to the colored pattern coating ink. Examples of the dispersant include a nonionic surfactant such as polyoxyethylene alkyl ether, and examples of the ionic surfactant include sodium alkylbenzene sulfonate, poly fatty acid salt, fatty acid salt alkyl phosphate, and tetra In addition to alkylammonium salts, organic pigment derivatives, polyesters, and the like can be given. A dispersing agent can be used individually or in mixture of 2 or more types.
The colored layers for each color can be adjusted according to the height of the black matrix, and can be formed with a thickness of 1 μm to 2 μm, for example.

(Production of color filter)
For the transparent substrate having the black matrix created in Examples 1 to 15, the red, green, and blue colored inks were used, and the inkjet printer equipped with a 12 pl, 180 dpi head was used to make red (R), green (G ) And blue (B) colored layers were formed.

The color filters thus obtained had good smoothness, and ΔEab in the pixels was measured. As a result, all were found to be good color filters with less color unevenness. ΔEab (color difference) was measured with a microanalyzer.
Moreover, when the presence or absence of the color mixture of the colored ink by inkjet was verified in the color filter having the black matrix created in Examples 2 to 7, the results shown in Table 5 were obtained.

It is explanatory drawing of the cross-sectional shape of the color filter provided with the black matrix of this invention. It is explanatory drawing of the cross-sectional shape of the color filter provided with the black matrix of this invention. It is explanatory drawing of the cross-sectional shape of the color filter provided with the black matrix produced without using a dispersing agent using a filler.

Explanation of symbols

1 ... transparent substrate 2 ... partition (black matrix)
3 ... Colored layer 4 ... Light shielding part 5 ... Non-light shielding part

Claims (6)

In the color filter that is formed by printing a colored layer by an inkjet method in the pixels delimited by the partition walls,
The color filter, wherein the partition wall comprises a resin composition containing at least a binder resin, a filler, and a dispersant. In the color filter that is formed by printing a colored layer by an inkjet method in the pixels delimited by the partition walls,
A color filter, wherein the partition wall is made of a resin composition containing at least a binder resin, a compound having a cationic polymerization property, a cation generator, a filler having a dehydrating property, and a dispersant. The color filter according to claim 1, wherein a part or all of the partition walls are black. The color filter according to claim 1, wherein the resin composition contains a fluorine-containing compound. The method for producing a color filter according to claim 1, wherein the resin composition contains a silicon-containing compound. In the color filter that is formed by printing a colored layer by an inkjet method in the pixels delimited by the partition walls,
The partition wall is made of a resin composition containing at least a binder resin, a filler, and a dispersant,
The partition wall has a square or reverse tapered shape,
A color filter, wherein the partition wall has a height of 1.5 μm or more.

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