JP2008203748A - Substrate with prot0rusion for alignment control and liquid crystal display using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate for a liquid crystal display with protrusions for liquid crystal alignment control which is excellent in electric characteristics and light shielding properties without impairing resolution properties and heat resistance, and to provide the liquid crystal display using the substrate for the liquid crystal display. <P>SOLUTION: In the substrate for the liquid crystal display provided with the protrusions for alignment control on a transparent substrate, the protrusions for alignment control are constituted of a cured product of a photosensitive resin composition containing at least an organic pigment, a dielectric tangent of the cured product of the photosensitive resin composition is ≤0.015 in the range of a driving frequency of the liquid crystal display and the content of the organic pigment is 5 to 70 wt.% to the cured product of the photosensitive resin composition. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a substrate for a liquid crystal display device with alignment control protrusions, and more particularly to a substrate having alignment control protrusions used in an alignment division vertical alignment type liquid crystal display device (MVA-LCD) and a liquid crystal display device using the same It is about.

  The alignment-divided vertical alignment liquid crystal display (MVA-LCD) controls the alignment of the liquid crystal molecules in one pixel so that the liquid crystal molecules have a plurality of tilt directions, so that uniform halftone display is possible in all directions. Is provided on a substrate (see, for example, Patent Document 1), and is said to be a liquid crystal display device having excellent contrast, viewing angle characteristics, and response speed.

  FIG. 1 is a schematic cross-sectional view for explaining the operation of the MVA-LCD. As shown in FIG. 1, a general MVA-LCD 10 includes a TFT-side substrate 11 provided with alignment control protrusions 13 and a color filter-side substrate 12 provided with alignment control protrusions 14 with liquid crystal molecules. 15 is disposed so as to be opposed to each other. The alignment control protrusions 13 and the alignment control protrusions 14 are provided at alternate positions.

  FIG. 1A shows the alignment state of the liquid crystal molecules 15 when no voltage is applied. When no voltage is applied, the liquid crystal molecules 15 are vertically aligned between the substrates 11 and 12, but the liquid crystal molecules of the alignment control protrusions 13 and the alignment control protrusions 14 are slightly inclined due to the influence of the inclined surfaces of the protrusions. Oriented.

  FIG. 1B shows the alignment state of the liquid crystal molecules 15 when a voltage is applied. When a voltage is applied, the liquid crystal molecules on the inclined surfaces of the alignment control protrusions 13 and the alignment control protrusions 14 begin to be inclined, and the liquid crystal molecules other than the inclined portions are sequentially aligned in the same manner. As a result, the alignment directions of the liquid crystal molecules can be made different from each other at the protrusion. That is, instead of rubbing treatment, the alignment of the liquid crystal molecules is controlled by providing protrusions, and the problem caused by dust generation during rubbing treatment can be fundamentally solved.

  In such an MVA-LCD, when no voltage is applied, the liquid crystal molecules are aligned vertically between the two substrates, but the liquid crystal molecules on the alignment control protrusion are slightly inclined due to the influence of the protrusion slope. is doing. For this reason, in the case of black display (no voltage applied), even if black is displayed in the region between the alignment control protrusions, light may leak strictly at the alignment control protrusion. For this reason, there is a problem that the display density of black display is slightly lowered and the contrast is lowered.

  In order to solve this problem, a method of forming the alignment control protrusion with a material that does not transmit visible light (hereinafter referred to as a light-shielding material) is used (for example, see Patent Document 1).

  However, Patent Document 1 does not describe any method for providing a material with a light-shielding property. As a method for imparting light-shielding properties to materials, generally, a method of adding a colorant to the resist is conceivable, but depending on the type and concentration of the colorant or dispersant, sufficient light-shielding properties may not be obtained, The patterning characteristics may be adversely affected.

  For example, when the affinity between the colorant and the developer is poor, a colorant residue is formed on the region between the alignment control protrusions, that is, on the pixels, or the colorant is partially formed on the side surface of the alignment control protrusion. If it remains in the pattern, it will cause a gritty pattern. In an MVA-LCD manufactured using such a substrate with protrusions for alignment control, display defects such as lowering of luminance or defective alignment of liquid crystals may occur.

  In addition, even if ions are eluted from the alignment control protrusion into the liquid crystal layer or the characteristics as a dielectric deteriorate, display defects such as display unevenness and image sticking may occur. In particular, in the case of a coloring material having a low light-shielding property, it is necessary to increase the amount of addition in order to obtain a sufficient contrast improving effect, so that the above-described problem tends to occur more easily.

  For example, although titanium black as a colorant is excellent in light-shielding properties, it has a large particle size, and therefore causes pattern jaggedness. Moreover, since it is expensive, there is a problem that it is difficult to meet the recent demand for lowering the price of LCD.

On the other hand, when a dye is used as the colorant, although the patterning characteristics and electrical characteristics are very excellent, there is a problem in heat resistance, such as a significant decrease in light-shielding property due to high-temperature baking during the formation of the alignment film. At present, it is difficult to obtain a contrast improvement effect.
Japanese Patent Laid-Open No. 2000-1931979

  The present invention has been made to solve the above-described problems, and is for a liquid crystal display device having a liquid crystal alignment control protrusion having excellent electrical characteristics and light shielding properties without impairing resolution, heat resistance, and the like. It is an object of the present invention to provide a liquid crystal display device having a high contrast without display defects such as display unevenness, luminance reduction and image sticking, using the substrate and the substrate for such a liquid crystal display device.

  In order to solve the above problems, a first aspect of the present invention is a substrate for a liquid crystal display device comprising an alignment control protrusion on a transparent substrate, wherein the alignment control protrusion contains at least an organic pigment. The dielectric tangent of the cured product of the photosensitive resin composition is 0.015 or less in the driving frequency range of the liquid crystal display device, and the content of the organic pigment is the photosensitive material. Provided is a substrate for a liquid crystal display device with an alignment control protrusion, characterized by being 5 to 70% by weight based on a cured product of the conductive resin composition.

  In such a liquid crystal display substrate, a red pigment and a blue pigment can be used as the main pigment component of the organic pigment. The dielectric constant of the cured product of the photosensitive resin composition is desirably 6 or less in the driving frequency range of the liquid crystal display device. Further, the alignment control protrusion can be formed on a color filter formed on a transparent substrate.

  According to a second aspect of the present invention, there is provided a liquid crystal display device comprising the above-mentioned substrate for liquid crystal display device with alignment control protrusions.

  According to the present invention, since the alignment control protrusion is formed using the photosensitive resin composition containing the organic pigment, the alignment control protrusion having excellent light-shielding property, resolution, electrical characteristics, and resistance is obtained. Therefore, there is no display defect such as display unevenness, luminance reduction, and burn-in, and an MVA-LCD with high contrast can be obtained.

  Hereinafter, embodiments of the present invention will be described in detail.

  As shown in FIG. 1, an MVA-LCD as an example of a liquid crystal display device according to an embodiment of the present invention includes a TFT-side substrate 11 provided with an alignment control protrusion 13 and an alignment control protrusion 14. It has a structure in which the substrate 12 on the color filter side is arranged to face each other with liquid crystal molecules 15 interposed therebetween. The alignment control protrusions 13 and the alignment control protrusions 14 are provided at alternate positions. On the substrates 11 and 12, alignment films 16 and 17 are further formed.

  The shape of the alignment control protrusion is not particularly limited as long as the liquid crystal molecules on the pixel can be regularly divided into two or more. However, the shape when viewed from the direction perpendicular to the substrate is a dot shape. It is preferable that there is regularity such as a stripe shape or a zigzag shape. In order to increase the viewing angle, the cross-sectional shape (vertical cross-sectional shape) when the alignment control protrusion is viewed from the direction horizontal to the substrate is an arc shape or a triangle, that is, a semicircular shape, a semielliptical shape, a polygonal pyramid shape. It is preferable that the upper surface does not have a flat portion, and the lower portion has a wider width, such as a shape or a conical shape.

  As described above, since the liquid crystal molecules of the alignment control protrusions are slightly inclined due to the influence of the inclination of the protrusions, the area between the alignment control protrusions is black in the case of black display (no voltage applied). Strictly speaking, light may leak at the alignment control projection. For this reason, there is a problem that the display density of black display is slightly lowered and the contrast is lowered.

  In order to obtain such an MVA-LCD that solves such a problem and improves contrast and does not cause display defects such as luminance reduction or image sticking, various characteristics of the alignment control protrusions are obtained. Repeated examination. As a result, the present inventors have found that a substrate for a liquid crystal display device having excellent characteristics can be obtained by using an organic pigment as a colorant of a photosensitive resin composition for forming alignment control protrusions.

  Compared with inorganic fine particle pigments, organic pigments have the advantage of being compatible with the photosensitive resin composition as a base and being able to form a pattern with excellent linearity without jaggedness. If necessary, it is possible to modify the particle size distribution and surface treatment according to the characteristics of the photosensitive resin composition used as the base and the required specifications of the alignment control protrusions. Wide. Further, by using a mixture of two or more of these pigments, it is possible to control the spectral spectrum, electrical characteristics, etc., and to form alignment control projections that match the target characteristics. In particular, it is preferable to mix pigments so as to have a spectral spectrum with little wavelength dependency in the visible region because the hue of the color filter is not changed.

  Further, as a result of various studies on the relationship between the characteristics of the substrate for a liquid crystal display device and the display defect in the MVA-LCD, the present inventors have found that the electrical characteristics of the alignment control projection material are the liquid crystal alignment defect and switching of the MVA-LCD. It has been found that the threshold deviation is greatly affected.

  The driving of the liquid crystal is generally performed with an AC waveform, but with the improvement of the response speed on the surface of the liquid crystal material, the influence within one rectangular wave, that is, the influence due to the DC waveform is not negligible.

  In the MVA-LCD 10 shown in FIG. 1, the alignment control protrusions 13 and 14 on the liquid crystal display device substrates 11 and 12 are arranged so as to face inward, and are inherent in the liquid crystal driving electric field. For this reason, in the MVA-LCD, an electrical characteristic balance between the alignment control protrusions and the members in other cells, for example, the liquid crystal 15 and the alignment films 16 and 17 is important.

  First, from the viewpoint of alternating current characteristics, the dielectric characteristics of the alignment control protrusion are important. Specifically, it can be explained by the value of the dielectric loss tangent, and is generally based on the following mechanism. That is, the dielectric loss tangent (tan δ) is the ratio of the amount of charge accumulated in the dielectric body and the amount of charge consumed. If the dielectric loss tangent is relatively small, the charge accumulated in the dielectric is retained, whereas if it is relatively large, the charge is consumed and not retained.

  Since the alignment control protrusions and other members in the cell such as liquid crystal and alignment film have properties as dielectrics, if the values of their dielectric loss tangents differ greatly, the charge retention state of the liquid crystal molecules is not uniform. The phenomenon of becoming. A non-uniform charge holding state causes a liquid crystal alignment failure, or a display failure such that image sticking occurs due to a threshold shift caused by an extra charge remaining. Accordingly, the dielectric loss tangent tan δ of the alignment control protrusion, the alignment film, and the liquid crystal layer is an important characteristic that determines the display characteristics of the MVA-LCD type color liquid crystal display device.

  The dielectric loss tangent is a value that depends on the measurement frequency, and the waveform of the driving signal of the liquid crystal contains some high-frequency components. Therefore, ideally, characteristics in a wide frequency range of 10 to 1 kHz must be considered. However, since one frame for driving the liquid crystal is actually about 60 Hz, it is appropriate to pay attention to the dielectric loss tangent at a period (second), that is, a frequency around 30 Hz and a frequency of about 10 to 100 Hz.

  In general, a liquid crystal material, an alignment film material, and the like are materials having a large ability to hold electric charges, that is, a material having a relatively small dielectric loss tangent, and generally have a value of about 0.005 to 0.02. Therefore, it is considered that the value of the dielectric loss tangent of the alignment control projection material used in the MVA-LCD is preferably the same as or lower than the liquid crystal material and the alignment film material.

  In view of the above, the present inventors have conducted various studies on the improvement of dielectric characteristics, and as a result, in the liquid crystal display substrate, the dielectric loss tangent of the material constituting the alignment control protrusion provided on the substrate is determined as the driving frequency. It has been found that by setting the content to 0.015 or less, preferably 0.008 or less, it is possible to effectively prevent deterioration in display quality such as alignment failure and threshold shift. The lower the dielectric loss tangent of the orientation controlling projection material, the better. From the viewpoint of the characteristics of the orientation controlling projection material, the lower limit is about 0.003 at present.

  Further, the relative dielectric constant of the orientation controlling protrusion material is also an important factor, and is preferably 6.0 or less in the range of the driving frequency. The relative dielectric constant is an index of the amount of charge accumulated in the dielectric body. If the relative dielectric constant of the alignment control protrusion is extremely large, the accumulated charge amount is compared with the members in the cell (liquid crystal, alignment film, etc.). The display balance is greatly lost, and image sticking occurs due to a threshold shift.

  The relative dielectric constant of the liquid crystal is generally about 10, and considering the film thickness and area of the liquid crystal layer and the alignment control protrusion, the relative dielectric constant of the alignment control protrusion is preferably 6.0 or less, more preferably 5. 0 or less. Although it is preferable that the relative dielectric constant is low, the lower limit is about 3.0 at present due to the characteristics of the material.

Next, from the viewpoint of direct current characteristics, it is desirable that the volume resistance value of the alignment control protrusion is equal to or higher than the volume resistance value of the liquid crystal. In general, since the liquid crystal for MVA-LCD has a volume resistance value of about 10 ¹² Ω · cm, the volume resistance value of the alignment control protrusion is preferably 10 ¹² Ω · cm or more, and preferably 10 ¹³ Ω · cm. -More preferably, it is cm or more. When the volume resistance value is smaller than 10 ¹² Ω · cm, a display defect such as image sticking occurs due to a threshold shift caused by the generation of a residual DC component.

  Next, an example of manufacturing a substrate for a liquid crystal display device according to an embodiment of the present invention will be described.

[Production of substrates for liquid crystal display devices]
In the following description, an example in which a color filter layer is provided on a transparent substrate as a substrate for a liquid crystal display device and an alignment control protrusion is formed thereon will be described. However, the present invention does not necessarily require a color filter layer and is not limited to the following description.

  First, a color filter is formed on a transparent substrate. In general, a color filter is obtained by forming a black matrix (K) for improving contrast on a transparent substrate and then a colored pixel layer of red (R), green (G), and blue (B). When this is used for a liquid crystal display device, it further has a structure in which a transparent conductive film and an alignment film are sequentially laminated. A transparent substrate on which such a color filter is formed is opposed to a counter substrate on which an electrode such as a thin film transistor is formed, and a liquid crystal layer is interposed therebetween to constitute an LCD.

  The transparent substrate is preferably in the form of a plate, and examples thereof include glass or a plastic sheet or film such as polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyethersulfone or polyacrylate. In addition, since the heating process is performed after forming the alignment control protrusions, a glass substrate excellent in heat resistance is preferable, and furthermore, a glass having a low coefficient of thermal expansion and excellent dimensional stability in the heating process is selected. It is preferable.

  The black matrix constituting part of the color filter can be formed using a known method. As such a method, for example, a method of forming a metal or metal oxide thin film such as chromium or titanium on a substrate by a method such as sputtering and patterning it by a technique such as etching, a photosensitive resin composition The material is mixed with light-shielding fine particles such as carbon black and metal oxide, and colorants such as multiple types of pigments or dyes, and this is formed as a photosensitive resin layer on the substrate and patterned by photolithography. Examples thereof include a method of forming, or a method of forming two or more colored pixel layers such as red, green, and blue, which will be described later, and may be formed by any method in the present invention.

  The colored pixel layer is provided at the opening of the black matrix, and usually a pixel pattern composed of three primary colors of a red pixel pattern (R), a green pixel pattern (G), and a blue pixel pattern (B) is arranged in a desired shape. It is a thing. Examples of the method for forming the colored pixel layer include known methods such as 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, any method may be used. good.

Next, a transparent conductive film is provided on the substrate on which the color filter is formed. The transparent conductive film is provided to control the behavior of the liquid crystal sandwiched between the substrates by transmitting an electrical signal. The transparent conductive film is essential for at least one of the opposing liquid crystal display device substrates. Usually, the transparent conductive film is formed immediately below the alignment control protrusion, but can also be provided on the alignment control protrusion by vapor deposition or the like. The material constituting the transparent conductive film is a material that is transparent and conductive and can be formed into a thin film. Usually, ITO (composite oxide of indium and tin) is used, and IZO (composite of indium and zinc is used). Oxide), SnO ₂ (tin dioxide), and the like are selected and formed by a technique such as sputtering or vacuum deposition.

  Subsequently, alignment control protrusions are formed. First, a photosensitive resin composition containing an organic pigment is coated on a substrate with a bar coater, applicator, wire bar, spin coater, roll coater, slit coater, curtain coater, die coater, comma coater, or other known coating. Apply using method. The photosensitive resin composition may be diluted in a solvent, prepared as a photosensitive solution, and applied to the substrate by the above method. In that case, the solvent must be removed after applying the photosensitive solution on the substrate. There is.

  Thereafter, pattern exposure is performed by irradiating light through a photomask having a predetermined pattern, followed by development with an alkali developer. When the photosensitive resin composition is positive, the exposed portion is dissolved and removed. When the photosensitive resin composition is negative, the unexposed portion is dissolved and removed, thereby forming alignment control protrusions faithful to the mask pattern. it can.

  The pattern exposure is performed using, for example, an ultra-high pressure mercury lamp, a high-pressure mercury lamp, a medium-pressure mercury lamp, a low-pressure mercury lamp, a xenon lamp, a halogen lamp, or the like, but is not limited thereto, and can be performed by other known methods. .

  The alignment control protrusion is subjected to a heating process after the photolithography process, whereby curing is accelerated, adhesion to the substrate is improved, and solvent resistance and chemical resistance are further imparted. Moreover, the shape becomes smooth by appropriate heat shrinkage and heat flow, and the orientation of liquid crystal molecules can be further improved. Furthermore, when the visible light transmittance is reduced due to a change in light absorption, it is possible to impart higher light shielding properties.

  Next, if necessary, an alignment film is provided on the substrate. The alignment film is provided for vertically aligning the negative liquid crystal compound. A transparent and insulating material is used for the alignment film, and polyimide resin or the like is generally used. The alignment film is formed by forming a polyimide resin solution, a polyamic acid solution, or the like by a known coating method or printing method, followed by baking.

  As an example of the configuration of the substrate for a liquid crystal display device having the alignment control protrusions in the present embodiment, a configuration in which a color filter, a transparent conductive film, and an alignment control protrusion are provided in this order on the substrate, or a color filter, a transparent conductive film, The structure which provided the protrusion for orientation control, the alignment film in this order, or the laminated body structure which provided the transparent protective film between arbitrary layers as needed can be mentioned.

  The transparent protective film has a function of flattening a step generated when the black matrix and the colored pixel layer are formed. As a material constituting the transparent protective film, photocurable, thermosetting, light and thermosetting resin compositions, resin cured products such as epoxy, acrylic and polyimide, or inorganic compounds formed by sputtering or vapor deposition, etc. Any material that can achieve the above-described object may be used. The transparent protective film can be formed in a thickness range of 0.5 to 3 μm in consideration of the surface state of the color filter layer.

  The alignment control protrusions used in the present embodiment are not limited to use in the layer configuration described above, and can be used in any configuration as necessary.

  Next, the photosensitive resin composition used for forming the alignment control protrusions in this embodiment will be described.

[Photosensitive resin composition]
In the present embodiment, the photosensitive resin composition used for forming the alignment control protrusions contains an organic pigment. This photosensitive resin composition may be either negative type or positive type, but the binder resin preferably has alkali solubility. In this case, the photosensitive resin composition can be developed with an aqueous alkaline solution and can be used in a conventional process, which is advantageous in terms of cost and is also preferable from the viewpoint of the environment.

  Moreover, it is preferable that the photosensitive resin composition is resin which has an aromatic ring from the point of an electrical property. Such a resin is not particularly limited, and examples thereof include resins having phenolic hydroxyl groups, carboxyl group-modified epoxy resins, and modified products thereof.

  Examples of the resin having a phenolic hydroxyl group include a cresol novolac resin, polyvinylphenol, and a copolymer of p-vinylphenol and styrene. Polyvinylphenol is a known method, for example, hydroxystyrenes which may have a substituent such as p-hydroxystyrene and 2- (p-hydroxyphenyl) propylene, or two or more radicals. It can be obtained by polymerizing in the presence of a polymerization initiator or a cationic polymerization initiator. Moreover, negative photosensitivity can also be given by introduce | transducing an unsaturated double bond group in a part of phenolic hydroxyl group.

  The epoxy resin can be used without any limitation as long as it has alkali developability. Among them, an unsaturated monobasic acid and a phenol compound are added to the polyfunctional epoxy resin, and a polybasic base is further obtained. Those crosslinked with an acid anhydride are particularly preferred. These resins may be used in combination of two or more in consideration of developability, sensitivity, thermoplasticity and the like.

  The binder resin in the photosensitive resin composition used in the present embodiment preferably has a weight average molecular weight (hereinafter referred to as Mw) in the range of 1000 to 40000 from the viewpoint of strength and developability, and in the range of 2000 to 15000. It is particularly preferred to have Mw. In addition, Mw is the weight average molecular weight of polystyrene conversion measured by GPC method.

  As the organic pigment contained in the photosensitive resin composition used in the present embodiment, commercially available ones can be used as long as they do not deteriorate the electrical characteristics. As the organic pigment, those having high color developability and high heat resistance, particularly high heat decomposition resistance are preferably used. An organic pigment etc. can be used individually or in mixture of 2 or more types. Further, the organic pigment may be refined by salt milling, acid pasting or the like.

 Below, the specific example of the organic pigment used for one Embodiment of this invention is shown with a color index number.

 Examples of red pigments include C.I. I. Pigment Red 7, 9, 14, 41, 48: 1, 48: 2, 48: 3, 48: 4, 81: 1, 81: 2, 81: 3, 97, 122, 123, 146, 149, 168, 177, 178, 179, 180, 184, 185, 187, 192, 200, 202, 208, 210, 215, 216, 217, 220, 223, 224, 226, 227, 228, 240, 246, 254, 255, H.264, 272, 279, etc. can be used.

  Examples of yellow pigments include C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 10, 12, 13, 14, 15, 16, 17, 18, 20, 24, 31, 32, 34, 35, 35: 1, 36, 36: 1, 37, 37: 1, 40, 42, 43, 53, 55, 60, 61, 62, 63, 65, 73, 74, 77, 81, 83, 86, 93, 94, 95, 97, 98, 100, 101, 104, 106, 108, 109, 110, 113, 114, 115, 116, 117, 118, 119, 120, 123, 125, 126, 127, 128, 129, 137, 138, 139, 147, 148, 150, 151, 152, 153, 154, 155, 156, 161, 162, 164, 166, 167, 168, 169, 170, 171, 172, 173, 174, 1 5,176,177,179,180,181,182,185,187,188,193,194,199,213,214, and the like.

  Examples of orange pigments include C.I. I. Pigment Orange 36, 43, 51, 55, 59, 61, 71, 73 and the like.

  Examples of the green pigment include C.I. I. Pigment Green 7, 10, 36, 37, etc. can be used.

  Examples of purple pigments include C.I. I. Pigment Violet 1, 19, 23, 27, 29, 30, 32, 37, 40, 42, 50 and the like.

 Examples of blue pigments include C.I. I. Pigment Blue 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 22, 60, 64, and the like.

 In order to ensure good coating properties, sensitivity, developability, etc., or to increase the coloring effect, dyes, natural pigments, or titanium oxide, barium sulfate, zinc white, lead sulfate, yellow lead, zinc yellow, red rose Colorants such as (red iron oxide (III)), cadmium red, ultramarine blue, bitumen, chromium oxide green, cobalt green, amber, titanium black, synthetic iron black, carbon black, and the like may be used supplementarily. From the viewpoint of coloring effect, dielectric loss tangent, and relative dielectric constant, it is desirable to use a blue pigment and a red pigment as main pigments.

  When the organic pigment is contained in the photosensitive colored resin composition used in the present embodiment, it is necessary to use a dispersant for dispersing the organic pigment. As the dispersant, a surfactant, a pigment derivative, a polymer dispersant (for example, manufactured by Aviscia Co., Ltd.) and the like are used. Although the addition amount of a dispersing agent is not specifically limited, It is preferable to set it as 1 to 50 weight% with respect to 100 weight% of compounding quantities of an organic pigment.

  In addition, the organic pigment may be coated with an appropriate resin as necessary in order to suppress the occurrence of foreign matter and coating film unevenness due to a solvent shock or the like during mixing with the resin composition. Here, dispersion of pigments and dispersants in a solution in which a photopolymerizable monomer and / or resin is dissolved in a solvent is a three-roll mill, a two-roll mill, a sand mill, a kneader, a dissolver, a high-speed mixer, a homomixer, or an attritor. It can carry out using various dispersion apparatuses, such as.

  In addition, when preparing a pigment composition by previously mixing a pigment and a dispersant, the pigment and the dispersant may be simply mixed. (A) Various pulverizers such as a kneader, a roll, an attritor, and a super mill (B) After the pigment is dispersed in the solvent, a solution containing the dispersant is added, and the dispersant is adsorbed on the pigment surface. (C) A solvent having a strong dissolving power such as sulfuric acid. It is preferable to employ a mixing method in which the pigment and the dispersant are co-dissolved and then co-precipitated using a poor solvent such as water.

  When two or more kinds of pigments are contained, for example, (b) after mixing two or more kinds of pigments, the obtained pigment mixture is finely dispersed in a pigment carrier by a known method. Each pigment or the like can be separately produced by mixing finely dispersed pigments in a pigment carrier.

  The amount of the organic pigment is preferably 5 to 70% by weight, and more preferably 10 to 40% by weight, based on the solid content ratio with respect to the cured photosensitive resin composition. When the amount of the organic pigment is less than 5% by weight, it is difficult to impart sufficient light-shielding properties, so that a sufficient contrast improvement effect cannot be obtained when a panel is formed. On the other hand, when it is more than 70% by weight, the light shielding property is too high, so that the sensitivity is lowered or the resolution is lowered. In addition, the electrical characteristics deteriorate due to an increase in dielectric loss tangent, which may cause burn-in when a panel is formed.

  In addition to the components described above, the photosensitive resin composition used in the present embodiment is compatible with the photosensitive resin composition as necessary for improving coatability, adhesion, heat resistance, chemical resistance, and the like. Additives such as solvents, plasticizers, stabilizers, surfactants, leveling agents, coupling agents, fillers and the like can be added as long as the object or effect of the present invention is not impaired.

  Examples of the solvent include dichloroethane, chloroform, acetone, 2-butanone, cyclohexanone, ethyl acetate, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 2-ethylethoxyacetate, 2-butoxyethyl acetate, 2-methoxy. Ethyl 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, 1,4-dioxane and the like.

  Next, specific examples of the embodiment of the present invention described above will be described, but the present invention is not limited to these examples.

Example 1
A Cr thin film was formed on a transparent substrate by sputtering, and then a black matrix was formed on the Cr thin film by photoetching. Further, a red photosensitive resin composition was applied thereon, exposed to light, developed, and post-baked to form red pixels. The same treatment was performed on the green photosensitive resin composition and the blue photosensitive resin composition to form green pixels and blue pixels.

  Next, ITO was formed on the entire surface by sputtering to form a transparent conductive film to obtain a color filter substrate. A transparent conductive film based on zinc oxide or tin oxide instead of ITO may be formed.

  Thereafter, the following components were mixed and stirred uniformly, and then filtered through a filter having an average pore diameter of 2 μm to prepare a photosensitive resin composition (1). This photosensitive resin composition (1) becomes alignment control protrusions through photolithography processes such as coating, exposure, development, and curing.

[Preparation of organic pigment dispersion (1)]
A mixture having the following composition was stirred and mixed uniformly, dispersed in a sand mill for 5 hours using zirconia beads having a diameter of 1 mm, and then filtered through a 5 μm filter to prepare an organic pigment dispersion (1) (pigment concentration 20). weight%).

Red pigment: C.I. I. 14 parts by weight of Pigment Red 254 ("Irga Four Red B-CF" manufactured by Ciba Geigy)
Blue pigment: C.I. I. Pigment Blue 15 6 parts by weight (“Rionol Blue ES” manufactured by Toyo Ink Manufacturing Co., Ltd.)
Dispersant ("Solsperse 20000" manufactured by Zeneca) 2.4 parts by weight Cyclohexanone 77.6 parts by weight The mixing method of the above components is not particularly limited as long as the dispersibility of the organic pigment is not significantly reduced. For example, in order to prevent agglomeration of organic pigment particles due to solvent shock, a method of slowly dropping a resist solution therein and gradually mixing the organic pigment dispersion while stirring it with a magnetic stirrer or the like can be mentioned.

The photosensitive resin composition thus obtained was applied to the color filter substrate with a spin coater to form a coating film of the photosensitive resin composition having a thickness of 1.9 μm. After pre-baking this photosensitive resin composition film, it was irradiated with 100 mJ / cm ² of light from an ultrahigh pressure mercury lamp through a photomask having a line pattern with a line width of 10 μm, and subsequently using a 0.5% aqueous potassium hydroxide solution. The film was developed for 70 seconds and then washed with water to form a rib-like pattern. Subsequently, post-baking was performed at 230 ° C./30 minutes to form a light-shielding alignment control protrusion.

  An MVA-LCD (vertical alignment mode liquid crystal display device) was produced using the color filter substrate having the light-shielding alignment control protrusions thus obtained.

Example 2
[Preparation of organic pigment dispersion (2)]
A mixture having the following composition was stirred and mixed uniformly, dispersed with a sand mill for 5 hours using zirconia beads having a diameter of 1 mm, filtered through a 5 μm filter, and an organic pigment dispersion (2%) having a pigment concentration of 18.6% by weight. ) Was produced.

Red pigment: C.I. I. Pigment Red 254 11.6 parts by weight ("Irga Four Red B-CF" manufactured by Ciba Geigy)
Yellow pigment: C.I. I. Pigment Yellow 139 2 parts by weight (“Irgafore Yellow 2R-CF” manufactured by Ciba Geigy)
Blue pigment: C.I. I. Pigment Blue 15 5 parts by weight (“Rionol Blue ES” manufactured by Toyo Ink Manufacturing Co., Ltd.)
Dispersant ("Solsperse 20000" manufactured by Zeneca) 2.4 parts by weight Cyclohexanone 79 parts by weight The same procedure as in Example 1 except that 15 g of the organic pigment dispersion (1) was changed to 16 g of the organic pigment dispersion (2). A photosensitive resin composition (2) was prepared, and a color filter substrate having alignment control protrusions was obtained using this. Further, an MVA-LCD was produced using this color filter substrate.

Example 3
Example 1 except that the negative resist composed of the following components was used instead of 100 g of the positive resist (MP-LC100 manufactured by Rohm and Haas) and the organic pigment dispersion (1) was increased to 26.4 g. Similarly, a photosensitive resin composition (3) was prepared.

Binder resin (Maruzen Petrochemical "Marcalinker M") 10g
Photopolymerizable monomer ("Aronix M-402" manufactured by Toa Gosei Co., Ltd.) 8g
Photopolymerization initiator (“IrgOXE01” manufactured by Ciba Specialty Chemicals) 1.7 g
Cyclohexanone (Kanto Chemical Co., Inc.) 55g
Using this photosensitive resin composition (3), a color filter substrate having alignment control protrusions was obtained. Further, an MVA-LCD was produced using this color filter substrate.

Comparative Example 1
A color filter substrate having alignment control protrusions was prepared in the same manner as in Example 1 except that the positive resist itself was used as the photosensitive resin composition without adding the organic pigment dispersion, and the exposure amount was 50 mJ / cm ^2. Obtained. Further, an MVA-LCD was produced using this color filter substrate.

Comparative Example 2
A photosensitive resin composition was prepared in the same manner as in Example 1 except that the amount of the organic pigment dispersion (1) was increased to 53 g, and this was used to adjust the exposure amount to 1000 mJ / cm ² and have alignment control protrusions. A color filter substrate was obtained. Further, an MVA-LCD was produced using this color filter substrate.

Comparative Example 3
A photosensitive resin composition was prepared in the same manner as in Example 1 except that the amount of the organic pigment dispersion (1) was reduced to 3 g, and the exposure amount was adjusted to 50 mJ / cm ² using this to have alignment control protrusions. A color filter substrate was obtained. Further, an MVA-LCD was produced using this color filter substrate.

Comparative Example 4
Photosensitive resin in the same manner as in Example 1 except that 5 g of titanium black dispersion (manufactured by Mitsubishi Materials Corporation, titanium black 10S, cyclohexanone solution having a pigment concentration of 20% by weight) was used instead of the organic pigment dispersion (1). A composition was prepared, and an exposure amount was set to 100 mJ / cm ² using this composition to obtain a color filter substrate having alignment control protrusions. Further, an MVA-LCD was produced using this color filter substrate.

Comparative Example 5
[Preparation of organic pigment dispersion (3)]
A mixture having the following composition was stirred and mixed uniformly, dispersed with a sand mill for 5 hours using zirconia beads having a diameter of 1 mm, filtered through a 5 μm filter, and an organic pigment dispersion (3) having a pigment concentration of 20% by weight was obtained. Produced.

Purple pigment: C.I. I. Pigment Violet 23 20 parts by weight (BASF “Paliogen Violet 5890”)
Dispersant (“Solsperse 20000” manufactured by Zeneca) 2.4 parts by weight
77.6 parts by weight of cyclohexanone A photosensitive resin composition was prepared in the same manner as in Example 1 except that 10 g of the organic pigment dispersion (3) was used instead of the organic pigment dispersion (1). A color filter substrate having an alignment control protrusion was obtained with an exposure amount of 100 mJ / cm ² . In addition, a liquid crystal display device (MVA-LCD) was manufactured using this color filter substrate.

Comparative Example 6
[Preparation of organic pigment dispersion (4)]
A mixture having the following composition was stirred and mixed uniformly, dispersed with a sand mill for 5 hours using zirconia beads having a diameter of 1 mm, filtered through a 5 μm filter, and an organic pigment dispersion (4) having a pigment concentration of 20% by weight was obtained. Produced.

Green pigment: C.I. I. 20 parts by weight of Pigment Green ("" manufactured by Toyo Ink Co., Ltd.)
Dispersant ("Solsperse 20000" manufactured by Zeneca) 2.4 parts by weight Cyclohexanone 77.6 parts by weight Example 1 except that 30 g of the organic pigment dispersion (4) was used instead of the organic pigment dispersion (1). A photosensitive resin composition was prepared in the same manner, and an exposure amount was set to 300 mJ / cm ² to obtain a color filter substrate having alignment control protrusions. Further, an MVA-LCD was produced using this color filter substrate.

  The evaluation results of the photosensitive resin compositions and MVA-LCD used in Examples 1 to 3 and Comparative Examples 1 to 6 are shown in Table 1 below. The evaluation rank was determined according to the following.

<Volume resistance value>
Aluminum was vapor-deposited on a glass plate having a thickness of 0.7 mm through a metal mask having an electrode pattern by a general vacuum vapor deposition method to form an electrode having a thickness of 1500 angstrom. Subsequently, the photosensitive resin compositions used in Examples 1 to 3 and Comparative Examples 1 to 4 were applied by spin coating so as to have a thickness of about 2 μm, and dried at 80 ° C. for 10 minutes. Thereafter, unnecessary portions other than those on the aluminum electrode were removed, heat-dried at 230 ° C. for 30 minutes using a hot air dryer, and an aluminum electrode was formed by the same method as above to prepare a test piece.

  This test piece has a structure in which a cured product of the photosensitive resin composition is sandwiched between 10 mm × 10 mm square aluminum electrodes with a thickness of about 1.5 μm. About this test piece, the electric current value when direct-current voltage 1V was applied was measured using C-54 (product made from Micronics) and a high voltage current measurement unit (product made from Keesley), and volume resistance value was computed.

<Dielectric loss tangent, relative permittivity>
With respect to the above test piece, the real part and the imaginary part of the impedance were measured with an impedance analyzer (Solartron 1260 manufactured by Toyo Technica Co., Ltd.) at a constant applied voltage of 1 V, and the values of dielectric loss tangent and relative dielectric constant at 30 Hz were calculated. .

<Contrast>
As compared with the MVA-LCD produced in Comparative Example 1, the case where the contrast was improved by 8% or more was evaluated as ◯, and the case where it was less than 8% was evaluated as ×.

<Burning>
A time T required for an afterimage to appear when a black and white checker pattern is displayed on the display area of the MVA-LCD for a long time (this time is T) and then a predetermined halftone is displayed on the entire display area. It was measured. A case where the time T was 100 hours or more was evaluated as ◯, a case where the time T was 24 hours or more and less than 100 hours was evaluated as Δ, and a case where the time T was less than 24 hours was evaluated as ×.

The above results are shown in Table 1 below.

  As shown in Table 1 above, in Examples 1 to 3 in which alignment control protrusions were formed using a photosensitive resin composition to which an appropriate amount of an organic pigment was added as a light shielding material, the alignment control protrusions having good electrical characteristics. Could be formed. In addition, the MVA-LCD manufactured using this has a contrast change of plus 8% or more compared to the MVA-LCD of Comparative Example 1 using a resist itself containing no organic pigment as a photosensitive resin composition. In addition, there was no display defect such as burn-in and good characteristics were exhibited.

  On the other hand, in Comparative Example 2 in which the amount of the organic pigment exceeds 70% with respect to the cured product of the photosensitive resin composition, the light transmittance at the time of exposure is too low, so that the organic pigment is not sufficiently cured and around the pattern It was not possible to form an orientation control protrusion having a good shape, such as a residue remaining. In Comparative Example 3 using the photosensitive resin composition having an organic pigment content of less than 5%, the characteristics of the alignment control protrusions were good, but a sufficient contrast improvement effect was not obtained.

  Further, in Comparative Example 4 in which titanium black was used instead of the organic pigment, the titanium black had a large particle size, so that the pattern was not smooth and it was impossible to form a well-shaped alignment control protrusion. Further, in Comparative Examples 5 and 6, purple pigments and green pigments, which are organic pigments, were used, but because the dielectric loss tangent was larger than 0.015, burn-in occurred when a panel was formed.

It is sectional drawing which shows the liquid crystal display device using the board | substrate which has the protrusion for liquid crystal orientation control which concerns on one Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... MVA-LCD, 11 ... TFT side substrate, 12 ... Color filter side substrate, 13, 14 ... Projection for alignment control, 15 ... Liquid crystal molecule, 16, 17 ... Alignment film.

Claims (5)

  A substrate for a liquid crystal display device comprising an alignment control protrusion on a transparent substrate, wherein the alignment control protrusion is composed of a cured product of a photosensitive resin composition containing at least an organic pigment, and the photosensitive resin composition The dielectric loss tangent of the cured product is 0.015 or less in the driving frequency range of the liquid crystal display device, and the content of the organic pigment is 5 to 70% by weight with respect to the cured product of the photosensitive resin composition. A substrate for a liquid crystal display device with an alignment control protrusion, characterized in that the substrate is provided.   The substrate for a liquid crystal display device with alignment control protrusions according to claim 1, wherein main pigment components of the organic pigment are a red pigment and a blue pigment.   3. The substrate for a liquid crystal display device with alignment control protrusions according to claim 1, wherein the dielectric constant of the cured product of the photosensitive resin composition is 6 or less in a driving frequency range of the liquid crystal display device.   The substrate for a liquid crystal display device with an alignment control protrusion according to claim 1, wherein the alignment control protrusion is provided on a color filter formed on the transparent substrate.   A liquid crystal display device comprising the substrate for a liquid crystal display device with an alignment control protrusion according to claim 1.

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