JP2009053482A - Substrate for liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate for a liquid crystal display device having a protrusion for liquid crystal alignment control having excellent electric characteristics and light-shielding properties without spoiling patterning characteristics and reliability. <P>SOLUTION: The protrusion 27 for alignment control is a cured product of a photosensitive resin composition containing an organic pigment and a lower part of the protrusion for alignment control has a relational form to follow a recessed part 28 on the lower side thereof. The organic pigment content is 5 to 70 wt.% to the cured product of the photosensitive resin composition. The cured product of the photosensitive resin composition has dielectric tangent of ≤0.015 in a driving frequency range. The cured product of the photosensitive resin composition has optical density per μm film thickness of ≥0.2. A colored pixel layer 23 is provided between the protrusion 27 for alignment control and one surface of the substrate 21. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a vertically aligned (VA) type liquid crystal display (LCD), and more particularly, to alignment-divided vertical alignment (MVA, multi-domain vertical alignment).
The present invention relates to a substrate for a liquid crystal display device having alignment control protrusions used in an alignment type LCD.

  The MVA-LCD (alignment division vertical alignment type liquid crystal display device) controls the liquid crystal molecules to have a plurality of tilt directions in one pixel, and has alignment control protrusions so that uniform halftone display can be performed in all directions. It is a vertical alignment type liquid crystal display device provided on a substrate and is said to be a liquid crystal display device having excellent contrast, viewing angle characteristics, and response speed.

  FIGS. 1A and 1B are explanatory views schematically showing the operation of the MVA-LCD in its cross section. As shown in FIGS. 1A and 1B, a general MVA-LCD (10) includes a TFT side substrate (11) provided with alignment control protrusions (13) via liquid crystal molecules (15). And the color filter side substrate (12) provided with the alignment control protrusions (14). However, the alignment control protrusions (13) and the alignment control protrusions (14) are in alternate positions. It is like that.

  FIG. 1A shows a state when no voltage is applied, and when no voltage is applied, the liquid crystal molecules (15) are vertically aligned between the two substrates, but the alignment control protrusion (13) and the alignment control protrusions. The liquid crystal molecules in part (14) are slightly tilted due to the influence of the slopes of the protrusions. FIG. 1B shows a state when a voltage is applied. When a voltage is applied, the liquid crystal molecules on the slopes of the protrusions begin to tilt, and the liquid crystal molecules other than the tilted portions sequentially have the same orientation. That is, the alignment of the liquid crystal molecules is controlled by providing protrusions instead of the rubbing treatment, and the problem due to dust generation during the rubbing treatment can be fundamentally solved.

  The shape of the alignment control protrusion is not particularly limited as long as the liquid crystal molecules on the pixel are regularly divided into two or more, but the shape when viewed from the direction perpendicular to the substrate is as follows. It is preferable to have regularity such as a dot shape, a stripe shape, or a zigzag shape. In addition, 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, or It is preferable that the upper surface does not have a flat portion and has a shape that becomes wider at the lower portion, such as a conical shape.

However, as described above, the liquid crystal molecules of the alignment control protrusion are slightly inclined due to the influence of the inclination of the protrusion, so that in the case of black display (no voltage applied), the alignment control protrusion Strictly speaking, light may leak from the alignment control protrusion even if the gap is black. For this reason, there is a problem that the contrast is lowered due to light leakage during black display.
In order to solve this problem, a method of forming alignment control protrusions using a material that does not transmit visible light (hereinafter referred to as a light-shielding material) is employed (see Patent Document 1).

As a method for imparting light shielding properties, a method of adding a coloring material to a conventional resist is generally considered. However, in order to provide sufficient light-shielding properties, the effect does not appear unless a sufficient coloring material is added.
However, if the concentration of the colorant is increased too much, there are problems such as a negative effect on patterning characteristics such as a decrease in sensitivity and a residue remaining after development, and an adverse effect on reliability such as elution of the colorant into the liquid crystal.

In addition, the vertical cross-sectional shape of the orientation control protrusion is preferably such that there is no flat portion on the upper surface and the lower portion is wider. For this reason, the film thickness decreases as it goes to the peripheral edge of the alignment control protrusion. Therefore, for example, even if the light shielding property at the film thickness per 1 μm is sufficient, the film thickness becomes thinner and the light shielding property of the portion is lowered as it approaches the peripheral portion of the alignment control protrusion. Therefore, sufficient light shielding properties are not obtained.
Japanese Patent Laid-Open No. 2000-1931979

The present invention has been made to solve the above-described problems. In the protrusions provided for controlling the orientation of the MVA-LCD, the concentration of the coloring material is not increased excessively, that is, the patterning characteristics and reliability are improved. It is an object of the present invention to provide a substrate for a liquid crystal display device having a liquid crystal alignment control protrusion having excellent electrical characteristics and light shielding properties without loss.
By using the substrate for a liquid crystal display device, it is possible to provide an MVA-LCD having high contrast without display defects such as burn-in.

  The present invention provides a substrate for a liquid crystal display device in which alignment control protrusions are disposed on one side of the substrate, wherein the alignment control protrusions are provided in advance on the one side of the substrate as a cured product of a photosensitive resin composition containing an organic pigment. A substrate for a liquid crystal display device, wherein the substrate is formed in a concave portion, and a lower portion of the alignment control protrusion has a shape following the shape of the concave portion.

  In the liquid crystal display substrate according to the present invention, the organic pigment content is 5 to 70% by weight based on the solid content of the photosensitive resin composition. It is a board | substrate for apparatuses.

  According to the present invention, in the substrate for a liquid crystal display device according to the above invention, the dielectric loss tangent of the alignment control protrusion is 0.015 or less in the driving frequency range of the liquid crystal display device. It is.

  Further, the present invention is the substrate for a liquid crystal display device according to the above invention, wherein the alignment control projection has an optical density of 0.2 or more per 1 μm of film thickness.

  In addition, the present invention provides the substrate for a liquid crystal display device according to the above invention, wherein a colored pixel layer is provided between the alignment control projection and one surface of the substrate.

  The present invention also provides the substrate for a liquid crystal display device according to the above invention, wherein the concave portion is provided in a colored pixel layer.

When the alignment control protrusions were formed using the photosensitive resin composition of the present invention, the alignment control protrusions having excellent light shielding properties could be obtained. In addition, with appropriate heat shrinkage and heat flow, it becomes possible to further improve the alignment of liquid crystal molecules with good dimensional accuracy along the shape of the lower part. Furthermore, since the peripheral edge portion also has a light shielding property combined with the film thickness of the lower portion, it is possible to impart a higher light shielding property. In addition, since the pigment concentration for providing sufficient light-shielding properties can be reduced, alignment control protrusions having resolution, electrical characteristics, and resistance can be formed. Therefore, there was no display defect such as display unevenness, luminance reduction, and burn-in, and an MVA-LCD having a high contrast could be obtained.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 2 is a schematic view showing a cross section of an example of a substrate for a liquid crystal display device according to the present invention. An example of this is a substrate for a liquid crystal display device in which a colored pixel layer is provided on a transparent substrate and an alignment control protrusion is formed thereon.

  The substrate for a liquid crystal display device is obtained by forming a color filter on a transparent substrate 21, and further laminating a transparent conductive film layer 24, an alignment control protrusion 27, and an alignment film layer 26 in this order. Here, the color filter is formed by forming a black matrix 22 for improving contrast on a transparent substrate, and then a colored pixel layer 23 of red (R), green (G), and blue (B). This liquid crystal display device substrate is opposed to, for example, a counter substrate on which an electrode such as a thin film transistor is formed to constitute an LCD through a liquid crystal layer.

  The transparent substrate 21 is preferably plate-shaped, 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 projections, 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. Is preferred.

  The black matrix 22 constituting the color filter can be formed using a known method. For example, a thin film of a metal or metal oxide such as chromium or titanium is formed on a substrate by sputtering or the like and patterned by a technique such as etching, or carbon in a photosensitive resin composition. A mixture of light-shielding fine particles such as black and metal oxides and a colorant such as a pigment or dye composed of a plurality of types, which is formed as a photosensitive resin layer on a substrate and formed by a photolithography method, or shown later Examples include one in which two or more colored pixel layers made of red, green, blue, and the like are laminated to form the layer, but any method may be used in the present invention.

The colored pixel layer 23 is provided at the opening of the black matrix 22 and is generally composed of colored pixel layers of three primary colors of a red colored pixel layer 23R, a green colored pixel layer 23G, and a blue colored pixel layer 23B. The colored pixel layers having a desired shape are adjacently and sequentially arranged.
At this time, a colored pixel layer having a concave portion 28 is formed so that the film thickness at the position where the alignment control protrusion enters is compared with other normal film thicknesses in the subsequent process. At this time, the depth of the concave portion of the colored pixel layer can be arbitrarily set depending on the light shielding property required for the alignment control protrusion. Further, the concave portions of the colored pixel layer are formed by controlling transmitted light through a photomask. For example, control by a mask pattern or control by a light shielding film is conceivable, but the present invention is not limited to this. The transparent conductive film layer 24 on the colored pixel layer 23 is sandwiched between substrates by transmitting an electrical signal. The transparent conductive film layer 24 is provided for controlling the behavior of the liquid crystal, and is essential for at least one of the opposing liquid crystal display device substrates. Normally, the transparent conductive film layer 24 is formed immediately below the alignment control protrusion, but it can also be provided on the upper layer of the alignment control protrusion by vapor deposition or the like.
The transparent conductive film layer 24 is made of a transparent and conductive material that can be formed into a thin film.
The TO (complex oxide of indium and tin) film, IZO (complex oxide of indium and zinc), SnO ₂ (tin dioxide) film, etc. are selected, and each of them is used for sputtering, vacuum deposition, etc. Formed.

The alignment control protrusions are first a photosensitive resin composition for forming protrusions, a bar coater, an applicator, a wire bar, a spin coater, a roll coater, a slit coater, a curtain coater, a die coater, a comma coater, or other known ones. Laminate using the coating method. The photosensitive resin composition may be diluted with a solvent, prepared as a photosensitive solution, and coated on the substrate by the above-described method. In that case, it is necessary to remove the solvent after coating on the substrate.
Next, it can be formed by irradiating light through a photomask having a predetermined pattern to perform pattern exposure and developing with an alkali developer.
When the photosensitive resin composition is a positive type, the exposed portion is dissolved and removed, and when the photosensitive resin composition is a negative type, the unexposed portion is dissolved and removed, whereby the alignment control protrusion 25 faithful to the mask pattern can be formed. The alignment control protrusions formed at this time are provided in the recesses 28 in the colored pixel layer.

  Examples of the pattern exposure include an ultra-high pressure mercury lamp, a high-pressure mercury lamp, a medium-pressure mercury lamp, a low-pressure mercury lamp, a xenon lamp, and a halogen lamp, but are not limited thereto and can be performed by other known methods. .

  The alignment control protrusions in the present invention can be heated after the photolithography process to accelerate the curing of the alignment control protrusions and improve the adhesion with the transparent conductive film layer 24. In addition, the protrusion 25 having a trapezoidal cross section after development becomes an alignment control protrusion 27 whose shape has become gentle due to fluidization by heating, and the lower portion of the alignment control protrusion 27 has a shape following the shape of the recess 28.

  Here, the photosensitive resin composition used for forming the alignment control protrusion of the present invention may be either a negative type or a 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, the resin which has an aromatic ring from the point of an electrical property is preferable. 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 radical polymerization of hydroxystyrenes which may have a substituent such as p-hydroxystyrene and 2- (p-hydroxyphenyl) propylene, or a combination of two or more thereof, by a known method. It is obtained by polymerizing in the presence of an initiator or a cationic polymerization initiator. Furthermore, negative photosensitivity can be imparted by introducing an unsaturated double bond group into a part of the phenolic hydroxyl group.

  The epoxy resin can be used without any limitation as long as it has alkali developability, and among them, an unsaturated monobasic acid and a phenol compound are added to the polyfunctional epoxy resin, 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.

Moreover, it is preferable that the weight average molecular weight (henceforth Mw) of binder resin in a composition is the range of 1000-40000 from a heat resistant and developable viewpoint, Furthermore, 2000-1
A range of 5000 is particularly preferred. In addition, Mw is the weight average molecular weight of polystyrene conversion measured by GPC method.

  As the organic pigment in the present invention, 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 this invention is shown by 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, Red pigments such as H.264, 272, and 279 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 75, 176, 177, 179, 180, 181, 182, 185, 187, 188, 193, 194, 199, 213, 214 and the like.

Examples of the orange pigment 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. Green pigments such as Pigment Green 7, 10, 36, and 37 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 coatability, sensitivity, developability, etc., dyes, natural pigments, or titanium oxide, barium sulfate, zinc white, lead sulfate, yellow lead, zinc yellow, red rose (red iron oxide (III), Inorganic pigments such as cadmium red, ultramarine blue, bitumen, chromium oxide green, cobalt green, amber, titanium black, synthetic iron black, and carbon black can also be used in combination.

When the photosensitive pigment composition of the alignment control projection of the present invention contains an organic pigment, it is necessary to contain a dispersant for dispersing the organic pigment. As the dispersant, a surfactant, a pigment derivative, a polymer dispersant (for example, Avisia Corporation: Solsperse), or the like is used. Although the addition amount of a dispersing agent is not specifically limited, It is preferable to set it as 1-50 mass% with respect to 100 mass% of compounding quantities of an organic pigment. In addition, the organic pigment of the present invention 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 can be produced by a method such as mixing finely dispersed pigments in a pigment carrier.

  The content of these organic pigments is preferably 5 to 70% by weight, more preferably 10 to 40% by weight, based on the solid content of the photosensitive resin composition. When the amount is less than 5% by weight, sufficient light-shielding property cannot be imparted, 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 above-mentioned components, the photosensitive resin composition for alignment control protrusions in the present invention is compatible with additives as necessary for improving coating properties, adhesion, heat resistance, chemical resistance, etc., For example, a solvent, a plasticizer, a stabilizer, a surfactant, a leveling agent, a coupling agent, a filler 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.

  Further, by using an organic pigment as the coloring material for the alignment control protrusion, a substrate for a liquid crystal display device having excellent characteristics can be obtained. 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 with no jaggedness. If necessary, it is possible to modify the particle size distribution control, surface treatment, etc. according to the characteristics of the photosensitive resin composition as the base and the required specifications of the alignment control protrusions, and the range of material selection Is wide. Furthermore, 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 that a spectral spectrum having little wavelength dependency in the visible region does not change the hue of the color filter.

Furthermore, as a result of various studies on the relationship between the properties of the substrate for liquid crystal display devices and the display defects in the MVA-LCD, the present inventors have found that the electrical characteristics of the alignment control protrusions are the liquid crystal alignment defects and switching thresholds of the MVA-LCD. It has been found that it has a significant effect on the deviation. The driving of the liquid crystal is generally performed with an alternating current waveform, but with the improvement of the response speed on the liquid crystal material surface, the influence within one rectangular wave, that is, the influence due to the direct current waveform is not negligible.

  Here, in general, in the MVA-LCD, the alignment control protrusions constituting the liquid crystal display device substrate are arranged so as to face inward. Since it is inherent in the liquid crystal driving electric field, in MVA-LCD, it is important to balance the electrical characteristics between the alignment control protrusions and the members (liquid crystal, alignment film) in other cells.

  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. The dielectric loss tangent (tan δ) is the ratio between the amount of charge accumulated in the dielectric and the amount of charge consumed. When the dielectric loss tangent is relatively small, the electric charge accumulated in the dielectric is retained, whereas when it is relatively large, the electric charge is consumed and not retained.

  Since the alignment control protrusions and other members in the cell (liquid crystal, alignment film, etc.) 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. Occurs. 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 layer, and the liquid crystal layer is an important characteristic that determines the display characteristics of the MVA-LCD 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 to 120 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 200 Hz.

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

  Based on the above, the present inventors have conducted various studies on the improvement of the dielectric characteristics. 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 the drive frequency. It has been found that by setting the range to 0.015 or less, more preferably 0.008 or less, it is possible to effectively prevent deterioration in display quality such as orientation failure and threshold shift. The lower the dielectric loss tangent of the orientation controlling projection material, the better. However, about 0.003 is the lower limit at the present time due to the characteristics of the orientation controlling projection material.

  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 value is extremely large in the alignment control projection, the balance of the amount of charge accumulated between the members in the cell (liquid crystal, alignment film, etc.) is balanced. Display failure such as large collapse and burn-in due to 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. A lower relative dielectric constant is preferable, but about 3.0 is the lower limit at the present time due to material characteristics.

  An alignment film layer 26 is provided on the substrate as necessary. The alignment film layer is provided for vertically aligning the negative liquid crystal compound. A transparent and insulating material is used for the alignment film layer, and generally a polyimide resin or the like is used. The alignment film layer is formed by forming a polyimide resin solution, a polyamic acid solution, or the like by a known coating method or printing method, and then baking.

Moreover, you may form a transparent protective film layer according to a condition. At this time, the transparent protective film layer has a function of flattening a step generated when the black matrix and the colored pixel layer are formed. As a material for forming the transparent protective film layer, a photocurable photosensitive material is used. Any material that can achieve the above-described object, such as a resin composition, may be used.
In consideration of the surface state of the colored pixel layer 23, it can be formed in the range of 0.5 to 3 μm. At this time, the transparent protective layer is formed so that the film thickness at the position where the alignment control protrusion enters in the subsequent process is about 0 to 80% compared with other normal film thicknesses. The thin film process of the transparent protective layer may be controlled by a mask or a pattern, but is not limited thereto.

  Hereinafter, although an example is given and explained about an embodiment of the invention, the present invention is not limited to an example.

<Example 1>
[Formation of Colored Pixel Layer and Transparent Conductive Film Layer] A glass substrate was used as the transparent substrate 21, and a black matrix 22 was formed on the glass substrate. Next, a colored pixel layer 23 made of R (red), G (green), and B (blue) was formed on a glass substrate by a known pigment dispersion method (FIGS. 3A to 3D). The resist formulation and preparation conditions were formed under the following conditions.

Resist formulation The composition of the acrylic pigment-dispersed photosensitizer is as follows.
A: Pigment 6% by weight
(Breakdown)
Black color: C.I. I. Black pigment 7
-Red: C.I. I. Red pigment 177
-Green: C.I. I. Green pigment 36, yellow: C.I. I. Yellow pigment 139
-Blue: C.I. I. Blue pigment 15
All materials are indicated by color index (CI) numbers.
B: 6% by weight of an anionic acrylic copolymer having the following composition
・ Methyl methacrylate 1% by weight
・ Methacrylic acid 1% by weight
・ Hydroxymethacrylate 1% by weight
・ Butyl methacrylate 1% by weight
・ Cyclohexyl acrylate 2% by weight
C: Polyfunctional acrylic monomer 6% by weight
(Product name “Aronix M-300” manufactured by Toagosei Co., Ltd.)
D: 0.05% by weight of photopolymerization initiator
(Product name “Irgacure 907” manufactured by Ciba Specialty Chemicals)
E: 82.5% by weight of organic solvent
A photopolymerization type pigment-dispersed photosensitizer prepared by sufficiently mixing A to E with continuous thickness was prepared.

○ Creation conditions The colored pixel layer was created under the following conditions.
・ Coating conditions 1000 rpm, exposure amount 100 mJ / cm ² , exposure gap 150 μm, development time 60 seconds, baking conditions 230 ° C./60 minutes.
The developer was an inorganic alkali developer.

As a result, the thickness of the colored pixel layer 23 was 2.0 μm ± 0.2 μm for all of R, G, and B. At this time, a light-shielding film made of ITO (Indium Synoxide) was formed on a photomask corresponding to the part where the protrusions were formed. The transmittance of ITO was set to about 35% of the transmittance when no ITO was formed at a wavelength of 365 nm. Through this photomask, exposure, development and curing steps were performed. A concave portion 28 having a line width of 10 μm and a depth of 0.5 μm was formed (FIGS. 3C and 3D).
Next, an ITO film was formed on the entire surface of the substrate on which these were formed by sputtering to form a transparent electrode 24 (FIG. 3E).

[Formation of liquid crystal alignment control protrusions]
Next, the liquid crystal alignment control protrusion 25 was produced. The resist used at this time and the preparation conditions were formed under the following conditions.

○ Composition / Positive resist LC-100 90% by weight
(Rohm and Haas, NV15%)
-Red pigment: C.I. I. Pigment Red 254 2.0% by weight
Blue pigment: C.I. I. Pigment Blue 15 1.0% by weight
・ Dispersant (“Solsperse 20000” manufactured by Zeneca) 0.3% by weight
・ Cyclohexanone 6.7% by weight
○ Creation conditions / coat conditions 1000rpm
・ Pre-baking conditions 115 ℃ at hot plate for 100 seconds ・ Exposure 100mJ / cm ²
・ Development 60 seconds ・ Bake conditions 230 ℃ ・ 30 minutes ○ Developer ・ Sodium carbonate 1.5% by weight
・ Sodium bicarbonate 0.5% by weight
・ Anionic surfactant (Kao / Berilex NBL) 8.0% by weight
・ 90% by weight of water
At this time, the mask was aligned with high accuracy through a rib pattern mask having a line width of 8 μm, and hardened at 230 ° C. to produce divided alignment control protrusions 27 on the colored pixel layer 23.
By this baking at 230 ° C., the protrusion 25 having a trapezoidal cross section after development becomes a protrusion 27 for orientation control having a gentle flow shape due to heating. In addition, the lower portion of the alignment control protrusion 27 has a shape that follows the shape of the recess 28. The slight flow of the protrusions has the effect of self-alignment (self-alignment) with the recesses 28 formed in advance in the colored pixel layer 23, and can improve alignment (FIGS. 3 (f) and 3 (g)).

  The liquid crystal split alignment control protrusion 27 formed at this time had a film thickness from the surface of the lowermost colored pixel layer of 1.7 μm at the uppermost position. The line width was 10 μm due to heat flow.

<Example 2>
A photosensitive resin composition was prepared in the same manner as in Example 1 except that a negative resist composed of the following components was used instead of the positive resist (MP-LC100 manufactured by Rohm and Haas).
・ Binder resin ("Maruka Linker M" manufactured by Maruzen Petrochemical Co., Ltd.) 8% by weight
・ Photopolymerizable monomer ("Aronix M-402" manufactured by Toa Gosei Co., Ltd.) 6% by weight
・ Photopolymerization initiator 1% by weight
(“IrgOXE01” manufactured by Ciba Specialty Chemicals)
・ Cyclohexanone (Kanto Chemical Co., Inc.) 85% by weight
Using this, 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 photosensitive resin composition similar to that of Example 1 was prepared except that there was no thinning (recessed part forming) step using a photomask for the colored pixel layer, and the alignment control protrusions were formed under the same conditions as in Example 1. A color filter substrate was 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 organic pigment composition ratio was changed to the following composition (pigment ratio of 5% or less), and the exposure amount was adjusted to 100 mJ / cm ² using this. A color filter substrate having alignment control protrusions was obtained.

○ Composition / Positive resist LC-100 96% by weight
(Rohm and Haas, NV15%)
-Red pigment: C.I. I. Pigment Red 254 0.3% by weight
Blue pigment: C.I. I. Pigment Blue 15 0.15% by weight
-Dispersant ("Solsperse 20000" manufactured by Zeneca) 0.05% by weight
・ Cyclohexanone 3.5% by weight
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 organic pigment composition ratio was changed to the following composition (pigment ratio of 70% or more), and the exposure amount was adjusted to 100 mJ / cm ² using this. A color filter substrate having alignment control protrusions was obtained.

○ Composition / Positive resist LC-100 30% by weight
(Rohm and Haas, NV15%)
-Red pigment: C.I. I. Pigment Red 254 10% by weight
Blue pigment: C.I. I. Pigment Blue 15 5% by weight
・ Dispersant ("Solsperse 20000" manufactured by Zeneca) 0.5% by weight
・ Cyclohexanone 3.5% by weight
Further, an MVA-LCD was produced using this color filter substrate.

<Comparative example 4>
A photosensitive resin composition was prepared in the same manner as in Example 1 except that the following pigment was used, and an exposure amount was set to 100 mJ / cm ² using this to obtain a color filter substrate having alignment control protrusions. Comparative Example 4 is an example having poor electrical characteristics.
Further, an MVA-LCD was produced using this color filter substrate.

○ Composition / Positive resist LC-100 95% by weight
(Rohm and Haas, NV15%)
Purple pigment: C.I. I. Pigment Violet 23 1.0% by weight
(BASF “Paliogen Violet 5890”)
・ Dispersant ("Solsperse 20000" manufactured by Zeneca) 0.2% by weight
・ Cyclohexanone 3.8% by weight
<Comparative Example 5>
A photosensitive resin composition was prepared in the same manner as in Example 1 except that a base positive material without organic pigment (usually a positive material) was used, and the exposure was adjusted to 300 mJ / cm ² using this to control orientation. A color filter substrate having protrusions for use was obtained. Further, an MVA-LCD was produced using this color filter substrate.

  Table 1 shows the evaluation results of the photosensitive resin compositions and MVA-LCDs used in Examples 1 to 2 and Comparative Examples 1 to 5. The evaluation rank was determined according to the following.

＜誘電正接＞
厚さ０．７ｍｍのガラス板上に、アルミを一般的な真空蒸着法により電極パターンを有する金属マスクを介して厚さ１５０ｎｍとなるように製膜し、電極を形成した。続いて上記実施例１〜２、および比較例１〜５にて用いた感光性樹脂組成物を約２μｍの厚さになるようにスピンコートにて塗布し、８０℃で１０分間乾燥した後、アルミ電極上以外の不要部分を除去し、熱風乾燥機を用いて２３０℃で３０分間加熱乾燥処理し、さらにアルミ電極を上記と同様の方法により形成して試験片を作製した。
該試験片は、１０ｍｍ×１０ｍｍの正方形のアルミ電極の間に本発明の感光性樹脂組成物の硬化物が約１．５μｍ厚で挟まれた構造のものである。上記の試験片について、インピーダンスアナライザ（（株）東陽テクニカ製 Ｓｏｌａｒｔｒｏｎ１２６０）により、印加電圧１Ｖ一定にてインピーダンスの実部と虚部とを測定し、３０Ｈｚにおける誘電正接の値を算出した。

<Dielectric loss tangent>
An electrode was formed on a glass plate having a thickness of 0.7 mm by depositing aluminum to a thickness of 150 nm through a metal mask having an electrode pattern by a general vacuum deposition method. Subsequently, the photosensitive resin compositions used in Examples 1-2 and Comparative Examples 1-5 were applied by spin coating so as to have a thickness of about 2 μm, and dried at 80 ° C. for 10 minutes. 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 described above to prepare a test piece.
The test piece has a structure in which a cured product of the photosensitive resin composition of the present invention is sandwiched between 10 mm × 10 mm square aluminum electrodes with a thickness of about 1.5 μm. With respect to the above test piece, an impedance analyzer (Solartron 1260 manufactured by Toyo Technica Co., Ltd.) was used to measure the real part and the imaginary part of the impedance at a constant applied voltage of 1 V, and the value of the dielectric loss tangent at 30 Hz was calculated.

<Contrast>
Compared to the MVA-LCD produced in Comparative Example 1, those that were improved by 8% or more were marked with ○, and those that were less than 8% were marked with ×.

<Burning>
A time T ₁ 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 ₀ ) and then a predetermined halftone is displayed on the entire display area. I investigated. The case where the time T ₁ is 100 hours or more is indicated by a circle, the case where the time T ₁ is 24 hours or more and less than 100 hours is indicated by a triangle, and the case where the time T ₁ is less than 24 hours is indicated by a mark.

  As shown in Table 1, in Examples 1 and 2 in which a photosensitive resin composition obtained by adding an appropriate amount of an organic pigment as a light shielding material was prepared, and alignment control protrusions were formed using the composition, electrical characteristics were obtained. As a result, it was possible to form good alignment control protrusions. In addition, the MVA-LCD produced using this had lower electrical characteristics and better shape than the comparative example 1 because the pigment concentration required to obtain the same OD value was lowered. The contrast change amount was 8% or more, and good characteristics without display defects such as burn-in were exhibited.

On the other hand, in Comparative Example 2 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. On the other hand, in Comparative Example 3 using a photosensitive resin composition containing more than 70% of an organic pigment, the transmittance is too low so that it is not sufficiently cured and a residue is left around the pattern. Protrusions could not be formed. In Comparative Example 4, although the orientation control protrusion could be formed, the dielectric loss tangent was larger than 0.015, and burn-in occurred when the panel was formed. Further, in Comparative Example 5, although the patterning and electrical characteristics were good, the contrast could not be increased.

(A), (b) is explanatory drawing which showed typically the operation | movement of MVA-LCD in the cross section. The cross section of an example of the board | substrate for liquid crystal display devices by this invention is shown by the schematic diagram. It is process explanatory drawing of an Example.

Explanation of symbols

10 ... MVA-LCD
DESCRIPTION OF SYMBOLS 11 ... TFT side substrate 12 ... Color filter side substrate 13, 14 ... Alignment control protrusion 15 ... Liquid crystal molecule 16, 17 ... Alignment film 21 ... Transparent substrate 22 ... Black Matrix 23... Colored pixel layer 24... Transparent conductive film layers 25 and 27... Orientation control protrusions 26.

Claims (6)

  In the substrate for a liquid crystal display device in which the alignment control protrusion is arranged on one side of the substrate, the alignment control protrusion is formed in a concave portion provided in advance on the one side of the substrate as a cured product of a photosensitive resin composition containing an organic pigment. A substrate for a liquid crystal display device, wherein a lower portion of the alignment control protrusion has a shape following the shape of the recess.   2. The substrate for a liquid crystal display device according to claim 1, wherein the content of the organic pigment is 5 to 70 wt% with respect to the solid content of the photosensitive resin composition.   3. The substrate for a liquid crystal display device according to claim 1, wherein a dielectric loss tangent of the alignment control protrusion is 0.015 or less in a driving frequency range of the liquid crystal display device.   4. The substrate for a liquid crystal display device according to claim 1, wherein an optical density per 1 [mu] m of film thickness of the alignment control protrusion is 0.2 or more.   5. The substrate for a liquid crystal display device according to claim 1, wherein a colored pixel layer is provided between the alignment control projection and one side of the substrate.   6. The substrate for a liquid crystal display device according to claim 5, wherein the concave portion is provided in the colored pixel layer.

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