JP4930394B2 - Liquid crystal display - Google Patents

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device including a color filter having an optimized thickness direction retardation value.

  A liquid crystal display device is a display element that utilizes the birefringence of liquid crystal molecules, and includes a liquid crystal cell, a polarizing element, and an optical compensation layer. Liquid crystal display devices are roughly classified into two types according to the type of light source: a transmissive type having a light source inside and a reflective type having a structure using an external light source.

  The transmissive liquid crystal display device has a configuration in which two polarizing elements are attached to both sides of a liquid crystal cell, and one or two optical compensation layers are disposed between the liquid crystal cell and the polarizing element. In the reflective liquid crystal display device, the reflector, the liquid crystal cell, one optical compensation layer, and one polarizing element are arranged in this order.

  In the liquid crystal cell, rod-like liquid crystal molecules sandwiched between two substrates are aligned and sealed, and a voltage is applied to the electrode layers disposed on both sides or one side of the two substrates, thereby producing a rod-like liquid crystal. This is a mechanism for switching light transmission / light-shielding by changing the orientation state of the active molecule.

  Such a liquid crystal cell has different alignment states of rod-like liquid crystal molecules, and has TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal), OCB (Optically Compensated Bend), STN (Supper Twisted). Various display modes such as Nematic), VA (Vertically Aligned), and HAN (Hybrid Aligned Nematic) have been proposed.

  The polarizing element generally has a configuration in which two transparent protective films made of triacetyl cellulose (hereinafter referred to as TAC) are attached to both sides of a polarizing film obtained by diffusing iodine into polyvinyl alcohol (hereinafter referred to as PVA). Have

Various optical compensation layers have been proposed. For example, in an IPS (lateral electric field) mode liquid crystal display device having good display characteristics in a range of a high viewing angle, a three-dimensional main refractive index _nx , _ny , to _{n z,} biaxial retardation film having a refractive index ellipsoid of _{n x} ≧ _{n y} ≧ _{n z} are combined (e.g., Ishinabe et, SID Digest, 1094. (2000) refer). Furthermore, by using two biaxial λ / 2 wavelength plates with different _nz sizes to compensate for each other's wavelength dispersion, the wide field of view that suppresses light leakage in the visible light region in black display is reduced. An angular IPS liquid crystal display device has been proposed (see, for example, Non-Patent Document 1).

  In recent years, liquid crystal display devices have been evaluated for their space-saving, light-weight, and power-saving properties due to their thinness, and at the same time they are rapidly expanding as television receivers, and at the same time, brightness, contrast, visibility in all directions, etc. There is a strong demand to further improve the display performance.

  Specifically, normally black mode IPS and VA liquid crystal display devices capable of higher contrast and wide viewing angle display are particularly preferred for TV applications, and the above-described optical compensation layer is often used. However, most of them are designed to have an optimum value so as to minimize color change when viewed from the front and black when viewed from the front, and when viewed obliquely.

Here, the optical compensation layer used in the above-described IPS mode liquid crystal display device is generally a biaxial retardation film _satisfying nx ≧ _ny ≧ _nz , or a TAC having no optical compensation function. In most cases, it is a transparent protective film, and when these films are used, the film has a positive thickness direction retardation Rth in the range of 0 to 150. In general, for an IPS mode liquid crystal display device in which the change in thickness direction retardation is small when the viewing angle is increased obliquely from the front (vertical direction) with respect to the display surface, these films are positive. The thickness direction retardation causes light leakage, and in particular causes a problem of deteriorating display characteristics viewed obliquely during black display. That is, when viewed from an oblique direction, the black display is tinted yellow or blue, which adversely affects visibility.

  Further, when the thickness direction retardation values (hereinafter referred to as Rth (R), Rth (G), and Rth (B)) of the red, green, and blue colored pixel layers constituting the color filter are different from each other, they are viewed obliquely. There may also be a problem that coloring is observed during black display. In particular, the thickness direction retardation values of the colored pixel layers of red, green and blue are not uniform, that is, Rth (R) <Rth (G)> Rth (B) or Rth (R)> Rth (G) <Rth ( B), the optical compensation layer exhibiting chromatic dispersion in one direction (continuous) with respect to the wavelength of light has a thickness direction retardation value for each color irregularity, which has a high level of display quality that is recently required. It becomes impossible to compensate by level.

  Specifically, the visibility from the front (vertical direction) with respect to the display surface is good, but in the visibility observed from an oblique angle such as 45 degrees (hereinafter referred to as oblique visibility), only a specific color is light. As a result, when it is displayed in black, red, blue, or greenish colors are produced.

  Since the retardation of the color filter was relatively small compared to other members used in the liquid crystal display device, this problem has not been emphasized so far, but high contrast and wide viewing angle characteristics are required. In LCD TVs, it has become a level that cannot be ignored.

  In particular, high-contrast liquid crystal display devices having 1000 or 3000 or more have been required to have a high image quality required for black display.

  Usually, since optical design is performed centering on green, if the retardations of the colored pixel layers of red, blue, and green are greatly different, a problem arises in oblique visibility as leakage light.

  For this, a low retardation TAC film or the like in which Rth is controlled to be almost zero by adding particles or the like that reduce the thickness direction retardation Rth to a film such as TAC has been proposed (see, for example, Patent Document 1). ).

  On the other hand, by adding a polymer having a planar structure group to the side chain of the colored polymer thin film, or by adding birefringence reducing particles having birefringence opposite to that of the polymer to the colored polymer thin film, Attempts have been made to reduce the amount of retardation of the filter (see, for example, Patent Documents 2 and 3).

  In addition, the in-plane retardation of the blue region of the color filter is made larger than that of the green and red regions, thereby increasing the amount of blue leakage light and offsetting the yellowing that is complementary to blue overall. A method for improving the entire display device from being colored yellow when the display device is viewed obliquely is disclosed (for example, see Patent Document 4).

  However, although the thickness direction retardation value of a film such as TAC has been variously devised so as to be close to zero, it is not completely zero, and a minute positive phase difference remains, which causes a problem. It was. In addition, since films requiring special processing such as these low retardation TAC films are basically expensive, there are many cases where the cost of the liquid crystal display device is not reduced.

  In addition, the thickness direction retardation value of the color filter varies greatly depending on the type of pigment used, and the thickness direction retardation value varies depending on the size and dispersion of the pigment or matrix resin (for example, acrylic resin or cardo resin). The present inventors have found that the degree becomes large, and the method of containing these polymer thin films and birefringence reducing particles cannot obtain a sufficient effect and cannot solve the above-mentioned problems.

  In particular, in a color filter based on a transparent resin represented by an acrylic resin having good dispersibility of an organic pigment for a high contrast liquid crystal display device, a required high contrast value (1000 or more, more preferably 3000 is required). It was difficult to improve oblique visibility while maintaining the above.

In addition, in the prior art, a color filter with a small birefringence is simply an excellent color filter, and even though a means for improving oblique visibility has been studied, as a high-contrast liquid crystal display device, There has been little research on means for reducing the difference in thickness direction retardation value to a level at which there is no problem in black display and adjusting the thickness direction retardation of each color to an optimum value.
Ishibe et al., Jpn. J. et al. Appl. Phys. 41, 4553. (See 2002). JP 2006-249328 A JP 2000-136253 A JP 2000-187114 A JP 2001-242460 A

  The present invention is made under the circumstances described above, and is not colored not only in the display surface observation direction (normal direction) but also in the observation from an oblique direction deviated by about 45 degrees from the observation direction, and the front (display surface method). (Line direction) An object is to provide a liquid crystal display device with good visibility.

In order to solve the above problems, an embodiment of the present invention includes a color filter including a red display pixel, a green display pixel, and a blue display pixel on a substrate, and an optical compensation layer disposed inside two polarizing plates. When the liquid crystal display device displays black and the chromaticity (u, y) expressed in the CIE 1960 color system is measured, the chromaticity (u (⊥ ), V (⊥)) and a chromaticity difference Δuv between chromaticities (u (45), v (45)) when viewed from an orientation inclined 45 ° from the normal direction of the display surface is expressed by the following formula (1). And the thickness direction phase difference value RRth of the red display pixel, the thickness direction phase difference value GRth of the green display pixel, and the thickness direction phase difference value BRth of the blue display pixel of the color filter are as follows. It is characterized by being an IPS system that satisfies formula (4). A liquid crystal display device is provided.

Δuv = [{u (⊥) −u (45)} ² + {v (⊥) −v (45)} ² ] ^1/2 <0.02 (1)

RRth <0 (2)
GRth <0 (3)
BRth> 0 (4)
(In the formula, RRth, GRth, and BRth respectively represent numerical values obtained from the product of the value obtained by subtracting the refractive index in the thickness direction from the average in-plane refractive index of each pixel and the thickness (nm) of the pixel.)
Further, the thickness direction retardation value RRth of the red display pixel of the color filter, the thickness direction retardation value GRth of the green display pixel, and the thickness direction retardation value BRth of the blue display pixel, and the thickness in the red region of the optical compensation layer. The direction retardation value Rth (R), the thickness direction retardation value Rth (G) in the green region, and the thickness direction retardation value Rth (B) in the blue region satisfy the following formulas (5) to (7). I can do it.

| RRth + Rth (R) | <30 (5)
| GRth + Rth (G) | <35 (6)
| BRth + Rth (B) |> 40 (7)
As the optical compensation layer, a transparent protective film made of triacetyl cellulose (TAC) can be used. Further, the above liquid crystal display device can be an IPS system.

  According to the present invention, each colored pixel is provided with a color filter in which the thickness direction retardation value of the red and green display pixels is a negative value and the thickness direction retardation value of the blue display pixel is a positive value. Variation in the polarization state of the light passing through the display region can be reduced, and a liquid crystal display device with good visibility in the oblique direction and front can be provided.

  Hereinafter, embodiments of the present invention will be described.

  When the liquid crystal display device according to an embodiment of the present invention displays black and measures the chromaticity (u, y) expressed in the CIE 1960 color system, the chromaticity (u ( The chromaticity difference Δuv between the chromaticity (u (45), v (45)) when viewed from a direction inclined 45 ° from the normal direction of the display surface (面), v (⊥)) ) Is satisfied.

Δuv = [{u (⊥) −u (45)} ² + {v (⊥) −v (45)} ² ] ^1/2 <0.02 (1)
Thus, when the chromaticity difference Δuv is less than 0.02, it can be determined that the visibility in the oblique direction is particularly good.

The thickness direction retardation value of each colored pixel layer of the color filter included in the liquid crystal display device according to the embodiment of the present invention is at least three colors of red 3 (R), green 3 (G), and blue 3 (B). A color filter provided with the colored pixels 3 is irradiated with continuous light including a wavelength in the transmitted light peak region in the visible region (for example, a light wavelength range of 380 nm to 780 nm) from the front and a plurality of inclined angles, and a spectroscopic ellipsometer, etc. It can be obtained by measuring the three-dimensional refractive index using the above phase difference measuring apparatus.
For example, the phase difference measurement is performed with light from at least two directions of the front surface and an incident angle of 45 degrees at a wavelength of 610 nm for a red color pixel, 550 nm for a green color pixel, and 450 nm for a blue color pixel, and Nx, Ny, Nz 3 After obtaining the dimensional refractive index, the thickness direction retardation value (Rth) is calculated from the following equation (8).

Rth = {(Nx + Ny) / 2−Nz} × d (8)
(In the formula, Nx is the refractive index in the x direction in the plane of the colored pixel layer, Ny is the refractive index in the y direction in the plane of the colored pixel layer, and Nz is the thickness direction of the colored pixel layer. (Refractive index, which is a slow axis where Nx is Nx ≧ Ny. D is the thickness (nm) of the colored pixel layer.)
At this time, when the substrate to be measured is a color filter, the measurement is performed through a mask processed so as to transmit only the single color pixel layers of R, G, and B. A phase difference value can be obtained.

  Further, for example, when light having a wavelength of 610 nm is used as incident light, the phase difference value caused only by the red colored pixel, in the case of 550 nm, the phase difference value caused only by the green colored pixel, in the case of 450 nm, As the phase difference value caused only by the blue colored pixel, an approximate value of the phase difference value of each single colored pixel layer can be estimated.

  In addition, when the board | substrate to measure is a single colored pixel layer (structure which formed the coating film of the monochromatic color filter coloring composition in the transparent substrate) in any one of R, G, and B, without passing through a mask The phase difference can be measured.

  Moreover, the thickness direction retardation value of films, such as TAC, can also be measured by the same method.

  The coloring composition used for the color filter of the liquid crystal display device according to an embodiment of the present invention is based on a polymer or monomer such as an acrylic resin or a cardo resin that can easily ensure high contrast, and at least an organic solvent, photopolymerization start It is a liquid coating liquid in which an organic pigment is dispersed in an agent or a curing agent.

  The color filter suitably used for the liquid crystal display device according to an embodiment of the present invention can process the colored composition as a color resist used in known photolithography or as ink such as inkjet or printing.

  In addition, the detail about the structural component of the coloring composition used for a color filter is mentioned later.

  The principle that characterizes the liquid crystal display device according to an embodiment of the present invention will be described.

The optical compensation layer used in the above-described IPS mode liquid crystal display device is generally a biaxial retardation film _satisfying n _x ≧ _ny ≧ _nz , or a transparent protective film such as TAC having no optical compensation function. In most cases, these films have a positive thickness direction retardation Rth in the range of 0 to 150. In general, for an IPS mode liquid crystal display device in which the change in thickness direction retardation is small when the viewing angle is increased obliquely from the front (vertical direction) with respect to the display surface, these films are positive. The thickness direction retardation causes light leakage, and causes a problem of deteriorating display characteristics viewed from an oblique direction particularly during black display. That is, when viewed from an oblique direction, the black display is colored yellow or blue, which adversely affects visibility.

  On the other hand, it is usually desirable that the absolute value of the birefringence of the color filter is 0.01 or less, that is, the thickness direction retardation value (Rth) is as close as possible to RRth = GRth = BRth = 0. The inventors of the present invention have different color filter layer retardations for each of the red, green, and blue color pixel patterns. Red indicates positive or negative retardation, blue indicates positive retardation, and green indicates negative retardation. I found out.

  As a result, the visibility from the front (vertical direction) with respect to the display surface is good, but only a specific color leaks light when viewed from an oblique angle such as 45 degrees (hereinafter referred to as oblique visibility). Therefore, when viewed from an oblique direction during black display, coloring such as reddish, bluedish, or greenish is produced.

  In a color filter of a liquid crystal display device, the most desirable value for the phase difference value Rth of each colored pixel varies depending on the combination with other members, but it is a biaxial property widely used in IPS mode liquid crystal display devices. In the case of the above retardation film or TAC film, since the thickness direction retardation value of these films has a positive value of at least zero or more, Rth of the color filter is preferably a negative value.

  More importantly, as the color filter increases in contrast, that is, the depolarization of the color filter decreases, the chromaticity when viewed from the front during black display approaches the chromaticity of the crossed Nicols of the polarizing plate. Is a point.

  The dichroism of the polarizing plate has also been improved. In recent years, high-contrast polarizing plates have been used, but most of the hues in crossed Nicols are bluish. That is, since there is much light leakage from the polarizing plate at a wavelength of around 400 nm, the hue when viewed from the front during black display is bluish.

  Therefore, it is necessary to select a combination that obtains the optimum oblique visibility in the optical member combination of the liquid crystal display device such as a liquid crystal, a polarizing plate, a retardation plate, and an alignment film, and when viewed from the front and obliquely. In order to minimize the color change of the chromaticity, it is necessary to make the chromaticity when viewed obliquely blue. As a result of intensive studies by the present inventors, it has been found that a liquid crystal display device having good oblique visibility can be obtained when each color thickness direction retardation value Rth of the color filter satisfies formulas (2) to (4). It was.

RRth <0 (2)
GRth <0 (3)
BRth> 0 (4)
That is, the thickness direction retardation value of the blue color pixel is positive, and the thickness direction retardation value of the green and red color pixels is negative, so that the thickness direction retardation value of the color filter has no effect when viewed from the front. When viewed obliquely, the light leakage in the blue region is greater than the light leakage in the red and green regions and becomes bluish, so that the color difference from the front chromaticity can be reduced.

  In the liquid crystal display device, the thickness direction retardation value RRth of the red display pixel of the color filter, the thickness direction retardation value GRth of the green display pixel, and the thickness direction retardation value BRth of the blue display pixel, and the optical compensation The thickness direction retardation value Rth (R) in the red region of the layer, the thickness direction retardation value Rth (G) in the green region, and the thickness direction retardation value Rth (B) in the blue region are represented by the following formulas (5) to (7). It has been found that a liquid crystal display device having better oblique visibility can be obtained by satisfying the above.

| RRth + Rth (R) | <30 (5)
| GRth + Rth (G) | <35 (6)
| BRth + Rth (B) |> 40 (7)
As described above, the present inventors are optimal in addition to Rth (R) = Rth (G)) = Rth (B) = 0 when combined with wavelength dispersion of a component other than a color filter, for example, a TAC film. We found that there is a value for the thickness direction retardation of the color filter.

  Next, a color filter suitable for use in the liquid crystal display device according to one embodiment of the present invention will be described.

  As shown in FIG. 1, a color filter suitable for use in a liquid crystal display device according to an embodiment of the present invention includes a black matrix 2 as a light shielding layer formed on a glass substrate 1 and at least a red color 3 ( R), green 3 (G), and blue 3 (B) are formed with colored pixels 3 of three colors. The color filter is not limited to these three colors, and a combination of complementary colors may be used, or a multi-color filter of three or more colors including complementary colors and other colors may be used.

  In order to obtain good front visibility, particularly a tightened color in black display, when the color display pixel is a color filter manufactured using a pigment-dispersed coloring composition, the particle size of the primary particles of the pigment In the distribution, it is preferable that the particle diameter d50 corresponding to 50% of the total amount in the integration curve of the number particle size distribution is 40 nm or less, and more preferably d50 is 30 nm or less. This is because, when the particle diameter d50 of the primary particles of the pigment is within such a range, a liquid crystal display device having good visibility not only from the oblique direction but also from the front direction can be obtained. The particle diameter d50 represents a particle diameter (equivalent circle diameter) corresponding to 50% of the total amount in the cumulative curve of the number particle size distribution.

Examples of red pixels include C.I. I. Pigment Red 7, 14, 41, 48: 2, 48: 3, 48: 4, 81: 1, 81: 2, 81: 3, 81: 4, 146, 168, 177, 178, 179, 184, 185, Red pigments such as 187, 200, 202, 208, 210, 246, 254, 255, 264, 270, 272, and 279 can be used, and a yellow pigment and an orange pigment can also be used in combination.
Examples of yellow pigments include C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 10, 12, 13, 14, 15, 16, 17, 18, 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, 93, 94, 95, 97, 98, 100, 101, 104, 106, 108, 109, 110, 113, 114, 115, 116, 117, 118, 119, 120, 123, 126, 127, 128, 129, 147, 151, 152, 153, 154, 155, 156, 161, 162, 164, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 179, 180, 181, 182, 187 188,193,194,199,198,213,214, 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.
When the red pixel contains one or more of diketopyrrolopyrrole red pigments and anthraquinone red pigments among these pigments, it is preferable because any Rth can be easily obtained. This is because the diketopyrrolopyrrole red pigment can be made either positive or negative by devising the finer treatment, and its absolute value can be controlled to some extent, and the anthraquinone red color This is because the pigment easily obtains Rth close to 0 regardless of the miniaturization treatment.

  The amount of diketopyrrolopyrrole red pigment and anthraquinone red pigment used is 10 to 90% by weight of diketopyrrolopyrrole red pigment and 5 to 70% by weight of anthraquinone red pigment based on the total weight of the pigment. It is preferable from the viewpoint of the hue, brightness, film thickness, contrast, etc. of the pixel. Particularly, when focusing on the contrast, the diketopyrrolopyrrole red pigment is 25 to 75% by weight, and the anthraquinone red pigment is 30 to 60%. It is more preferable to set it as weight%.

  The red pixel can contain a yellow pigment or an orange pigment for the purpose of adjusting the hue, but it is preferable to use an azo metal complex-based yellow pigment from the viewpoint of high contrast. The amount of the azo metal complex yellow pigment used is preferably 5 to 25% by weight based on the total weight of the pigment, and if it is less than 5% by weight, it becomes difficult to adjust the hue such as sufficient brightness improvement. When the content exceeds 30% by weight, the hue is excessively shifted to yellow, so that the color reproducibility tends to deteriorate.

  Examples of the diketopyrrolopyrrole red pigment include C.I. I. Pigment Red 254 and an anthraquinone red pigment include C.I. I. Pigment Red 177, an azo metal complex yellow pigment such as C.I. I. Pigment Yellow 150 is preferable in terms of excellent light resistance, heat resistance, transparency, coloring power, and the like.

  Examples of the green pixel include C.I. I. Green pigments such as Pigment Green 7, 10, 36, 37, and 58 can be used, and a yellow pigment can be used in combination. As this yellow pigment, the same pigments as those described in the description of the red pixel can be used.

  The green display pixel contains at least one of a halogenated metal phthalocyanine green pigment, an azo yellow pigment, and a quinophthalone yellow pigment among these pigments, because it is easy to obtain an arbitrary Rth. preferable. This is because the halogenated metal phthalocyanine green pigment can control the GRth to some extent by selecting the central metal, and the azo yellow pigment can convert a positive GRth to a quinophthalone yellow pigment regardless of the refining treatment. This is because a negative GRth can be obtained regardless of the miniaturization process.

  The amount of these pigments used is 30 to 90% by weight of the halogenated metal phthalocyanine green pigment, 5 to 60% by weight of the azo yellow pigment, and 5 to 60% of the quinophthalone yellow pigment based on the total weight of the pigment. % Is preferable from the viewpoint of pixel hue, brightness, film thickness, and the like. More preferably, the halogenated metal phthalocyanine green pigment is 50 to 85% by weight, the azo yellow pigment is 5 to 45% by weight, and the quinophthalone yellow pigment is 5 to 45% by weight.

  Examples of the halogenated metal phthalocyanine green pigment include C.I. I. Pigment Green 7, 36, and zinc halide phthalocyanine pigment C.I. I. Pigment Green 58, and azo-based yellow pigments include C.I. I. Pigment Yellow 150 and quinophthalone yellow pigments include C.I. I. Pigment Yellow 138 is preferable in terms of excellent light resistance, heat resistance, transparency, coloring power, and the like.

  Examples of blue pixels include C.I. I. Pigment Blue 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 22, 60, 64, and the like can be used, and a purple pigment can be used in combination. Examples of purple pigments used in combination include C.I. I. Pigment Violet 1, 19, 23, 27, 29, 30, 32, 37, 40, 42, 50 and the like.

  When the blue pixel contains at least one of a metal phthalocyanine blue pigment and a dioxazine purple pigment among these pigments, it is easy to obtain Rth close to 0 from negative. The amount of these pigments used is 40-100% by weight of the metal phthalocyanine-based blue pigment and 1-50% by weight of the dioxazine-based violet pigment based on the total weight of the pigment. From the viewpoint of thickness and the like, it is more preferable that the metal phthalocyanine blue pigment is 50 to 98% by weight and the dioxazine violet pigment is 2 to 25% by weight.

  Examples of metal phthalocyanine blue pigments include C.I. I. Pigment Blue 15: 6, and dioxazine-based purple pigments include C.I. I. Pigment Violet 23 is preferable in terms of excellent light resistance, heat resistance, transparency, coloring power, and the like.

  Further, in order to ensure good coatability, sensitivity, developability and the like while balancing saturation and lightness, an inorganic pigment can be used in combination with an organic pigment. Inorganic pigments include yellow lead, zinc yellow, red bean (red iron oxide (III)), cadmium red, ultramarine, bitumen, chromium oxide green, cobalt green and other metal oxide powders, metal sulfide powders, metal powders, etc. Can be mentioned. The inorganic pigment can further contain a dye within a range that does not decrease the heat resistance for color matching.

  The pigment contained in the colored pixel is preferably miniaturized and preferably has a small average primary particle size in order to achieve high brightness and high contrast of the color filter. The average primary particle diameter of the pigment can be calculated by taking the pigment with a transmission electron microscope and analyzing the image of the photograph.

  The average primary particle diameter of the pigment is preferably 40 nm or less, more preferably 30 nm or less, and still more preferably 20 nm or less. Moreover, it is preferable that an average primary particle diameter is 5 nm or more. When the average primary particle diameter of the pigment is larger than the upper limit value, the visibility of the liquid crystal display device during black display is poor. Moreover, when smaller than a lower limit, pigment dispersion | distribution becomes difficult, it becomes difficult to maintain stability as a coloring composition and to ensure fluidity | liquidity. As a result, the luminance and color characteristics of the color filter are deteriorated. In particular, an organic pigment having an average primary particle diameter exceeding 40 μm adversely affects front visibility.

  In addition, each color pixel formed on the transparent substrate is sandwiched between two polarizing plates, a backlight is applied from one polarizing plate side, and the light transmitted through the other polarizing plate is measured with a luminance meter. The contrast C calculated from the ratio of the light luminance (Lp) in the parallel state and the light luminance (Lc) in the orthogonal state is calculated from C = Lp / Lc, CS is only the substrate without colored pixels, and CR is When red pixel, CG represents green pixel, and CB represents blue pixel contrast, CR / CS> 0.45, CG / CS> 0.45, and CB / CS> 0.45, As shown in Tables 6 and 7 to be described later, the front visibility during black display of the liquid crystal display device is excellent. That is, it is possible to reproduce a tight black display with little light leakage.

When CR / CS> 0.45, CG / CS> 0.45, and CB / CS> 0.45 are not satisfied, that is, CR / CS ≦ 0.45, CG / CS ≦ 0.45, Alternatively, in the case of CB / CS ≦ 0.45, light leakage during black display increases and a liquid crystal display device with excellent front visibility cannot be obtained.
Further, by reducing the retardation difference for each color, the liquid crystal display device is excellent in both oblique visibility and front visibility.

  In addition, even if all of CR / CS> 0.45, CG / CS> 0.45, and CB / CS> 0.45 are satisfied, if the retardation difference for each color is large, the oblique visibility is insufficient. Sometimes.

  Means for controlling the average primary particle diameter and thickness direction retardation of the pigment include a method in which the pigment is mechanically pulverized to control the primary particle diameter and particle shape (called a grinding method), and a solution in a good solvent. A method in which a pigment having a desired primary particle size and particle shape is deposited by introducing it into a poor solvent (referred to as a precipitation method), and a method for producing a pigment having a desired primary particle size and particle shape during synthesis (referred to as a synthetic precipitation method) ) Etc. Depending on the synthesis method and chemical properties of the pigment to be used, an appropriate method can be selected for each pigment.

  Although each method will be described below, any of these methods may be used as a method for controlling the primary particle diameter and particle shape of the pigment contained in the colored pixel layer constituting the color filter according to the present embodiment. .

  In the grinding method, the pigment is mechanically kneaded using a ball mill, sand mill or kneader together with a grinding agent such as water-soluble inorganic salt such as salt and a water-soluble organic solvent that does not dissolve it. This is a method of obtaining a pigment having a desired primary particle size and particle shape by washing and removing the inorganic salt and the organic solvent, followed by drying. However, since the pigment may crystallize by the salt milling treatment, a method of preventing crystal growth by adding a solid resin or a pigment dispersant that is at least partially dissolved in the organic solvent during the treatment is effective.

  As for the ratio of the pigment and the inorganic salt, when the ratio of the inorganic salt is increased, the efficiency of miniaturization of the pigment is improved, but the processing amount of the pigment is decreased, so that productivity is lowered. In general, 1 to 30 parts by weight, preferably 2 to 20 parts by weight of the inorganic salt is used per 1 part by weight of the pigment. The water-soluble organic solvent is added so that the pigment and the inorganic salt are uniformly solidified. Although depending on the blending ratio of the pigment and the inorganic salt, the water-soluble organic solvent is usually added in an amount of 0.1% by weight per 1 part by weight of the pigment. Used in an amount of 5 to 30 parts by weight.

  In the case of the grinding method, more specifically, a small amount of a water-soluble organic solvent is added as a wetting agent to a mixture of a pigment and a water-soluble inorganic salt, and after kneading with a kneader or the like, the mixture is poured into water. Stir with a high speed mixer or the like to form a slurry. Next, the slurry is filtered, washed with water, and dried to obtain a pigment having a desired primary particle size and particle shape.

  The precipitation method is a method in which a pigment is dissolved in an appropriate good solvent and then mixed with a poor solvent to precipitate a pigment having a desired primary particle size and particle shape. The type and amount of the solvent, the precipitation temperature, the precipitation The primary particle size and particle shape can be controlled by the speed or the like.

  In general, pigments are difficult to dissolve in solvents, so the solvents that can be used are limited, but examples include strongly acidic solvents such as concentrated sulfuric acid, polyphosphoric acid, chlorosulfonic acid, or basic solvents such as liquid ammonia, dimethylformamide solution of sodium methylate, etc. It has been known.

  As a typical example of the precipitation method, there is an acid pasting method in which a solution in which a pigment is dissolved in an acidic solvent is poured into another solvent and reprecipitated to obtain fine particles. Industrially, a method of injecting a sulfuric acid solution into water is generally used from the viewpoint of cost. The sulfuric acid concentration is not particularly limited, but is preferably 95 to 100% by weight. The amount of sulfuric acid used with respect to the pigment is not particularly limited. However, if the amount is too small, the solution viscosity is high and handling becomes bad. Conversely, if the amount is too large, the treatment efficiency of the pigment is lowered. It is preferable.

  The pigment need not be completely dissolved. The temperature at the time of dissolution is preferably 0 to 50 ° C., and if it is lower than 0 ° C., the sulfuric acid may be frozen and the solubility is also lowered. Side reactions tend to occur at temperatures exceeding 50 ° C. The temperature of the water to be injected is preferably 1 to 60 ° C., and if the injection is started at a temperature exceeding 60 ° C., the operation is dangerous because it boils with the heat of dissolution of sulfuric acid. Freezing below 0 ° C. The injection time is preferably 0.1 to 30 minutes with respect to 1 part of the pigment. As the time increases, the primary particle size tends to increase.

  The primary particle size and particle shape of the pigment can be controlled while considering the size adjustment of the pigment by selecting a method that combines a precipitation method such as the acid pasting method and a grinding method such as the salt milling method. Further, it is more preferable because fluidity as a dispersion can be secured at this time.

  In salt milling or acid pasting, a dispersion aid such as a dye derivative, a resin-type pigment dispersant, or a surfactant, which will be described later, can be used in combination to prevent aggregation of the pigment accompanying primary particle size and particle shape control. .

  Further, by controlling the primary particle size and particle shape in the form of coexistence of two or more pigments, even a pigment that is difficult to disperse alone can be finished as a stable dispersion.

  There is a leuco method as a special precipitation method. When a vat dye, such as a flavantron, perinone, perylene, or indanthrone, is reduced with alkaline hydrosulfite, the quinone group becomes a hydroquinone sodium salt (leuco compound) and becomes water-soluble. The leuco method is a method that uses this phenomenon to precipitate a pigment having a small primary particle size insoluble in water by adding an appropriate oxidizing agent to the obtained aqueous solution and oxidizing it.

  Further, the synthetic precipitation method as another precipitation method is a method in which a pigment having a desired primary particle size and particle shape is precipitated simultaneously with the synthesis of the pigment. However, when the produced fine pigment is taken out of the solvent, if the pigment particles are not aggregated into large secondary particles, filtration, which is a general separation method, becomes difficult. It is applied to azo pigments synthesized in water.

  Furthermore, as a means for controlling the primary particle size and particle shape of the pigment, the primary particle size of the pigment is reduced by dispersing the pigment for a long time with a high-speed sand mill or the like (so-called dry milling method in which the pigment is dry pulverized). It is also possible to disperse at the same time.

  Moreover, in the color filter which concerns on this embodiment, the retardation regulator can be added to the color filter coloring composition of 1 or more colors especially in order to improve diagonal visibility. Retardation adjustment is an additive that can adjust the retardation in the thickness direction of a color filter in which a colored coating film of a color filter coloring composition is formed on a transparent substrate, a reflective substrate, or a semiconductor substrate. The compound constituting the retardation adjusting agent is preferably an organic compound with good dispersibility in order to ensure a high contrast of 1000 or 3000 or more. Specifically, particles in the form of particles, such as inorganic substances, can be used, but it is better to avoid them from the viewpoints of light scattering and depolarization.

In addition, when a color filter composed of a plurality of colored pixels is formed on a transparent substrate or the like, it may be added to all colors, but it can also be added to only one or two color pixels. .
As a specific example of the retardation adjusting agent, one or more selected from an organic compound having a planar structure group having one or more crosslinkable groups, a melamine resin, a porphyrin compound, and a polymerizable liquid crystal compound may be selected.

  Usually, it is considered that the retardation in the thickness direction of the entire film can be canceled only by adding particles having a planar structure group having birefringence opposite to that of pigment or other resin. However, simply adding particles having a planar structure group will cause the particles themselves to be randomly oriented, and the influence on the thickness direction retardation of the entire film will be small.

  Therefore, as a result of earnest investigations, the present inventors have shown that by providing a crosslinkable group to at least one of the planar structural groups, the thickness direction retardation of the entire film can be greatly changed and a sufficient effect can be exhibited. I found.

  That is, for example, by having a functional group that crosslinks in the photo-curing process or thermal curing process in the photolithography process, the planar structural group does not rotate freely, and the planar structural group is more susceptible to shrinkage during thermal curing. By being easily oriented and fixed in the same direction, it is possible to effectively exhibit a phase difference control function.

  As the planar structural group, it has at least one aromatic ring, and in the case of monocyclic hydrocarbon, phenyl group, cumenyl group, mesityl group, tolyl group, xylyl group, benzyl group, phenethyl group, styryl group, For polycyclic hydrocarbons such as cinnamyl and trityl groups, pentarenyl, indenyl, naphthyl, biphenylene, acenaphthylene, fluorene, phenanthryl, anthracene, triphenylene, pyrene, naphthacene, pentaphen, pentacene Known compounds such as a group, a tetraphenylene group, and a trinaphthylene group can be used. For heteromonocyclic compounds, pyrrolyl group, imidazolyl group, pyrazolyl group, pyridyl group, pyrazinyl group, triazine group, etc.For heteropolycyclic compounds, indolizinyl group, isoindolyl group, indolyl group, purinyl group, quinolyl group, isoquinolyl group, phthalazinyl Groups, naphthyridinyl groups, quinoxalinyl groups, cinolinyl groups, carbazolyl groups, carbolinyl groups, acridinyl groups, porphyrin groups, and the like, which have substituents such as hydrocarbon groups and halogen groups. Also good.

  The at least one crosslinkable group attached to the planar structure group includes an unsaturated polymerizable group (formula A, B, C, D, E, F) represented by the following formula, a functional group (formula I, J, K). , L, M, N, O), or a thermally polymerizable group (formulas G, H, P, Q, R, S, T, U), and an epoxy group (G, H) is more preferably used. And the formulas P to U are most preferably used.

Further, the unsaturated polymerizable group is more preferably an ethylenically unsaturated polymerizable group (formulas A, B, C, D), and —CH ₂ NHCOCH═CH ₂ , —CH ₂ NHCO (CH ₂ ) ₇ CH═CH (CH ₂ ) ₇ CH ₃ , —OCO (C ₆ H ₄ ) O (CH ₂ ) ₆ CH═CH _{2 and the} like are also preferably used.

These crosslinkable groups are glycidyl (meth) acrylate, 2- (meth) acryloyloxyisocyanate, tolylene-2, 4- when the planar structure group has at least one reactive functional group such as a hydroxyl group. It can be easily obtained by reacting with a compound having an ethylenically unsaturated group and a functional group that reacts with the reactive functional group such as diisocyanate.

As the melamine compound, a commercially available compound represented by the following general formula (1) can be preferably used, but any compound having the above-described planar structure group may be used, and a known compound can be used. Examples of melamine compounds are given below.

(In the formula, R ₁ , R ₂ and R ₃ are each a hydrogen atom, a methylol group, an alkoxymethyl group, an alkoxy n-butyl group, R ₄ , R ₅ and R ₆ are a methylol group, an alkoxymethyl group and an alkoxy n- A butyl group may be used as a copolymer in which two or more kinds of repeating units are combined, or two or more kinds of homopolymers or copolymers may be used in combination.
In addition to the above, compounds having a 1,3,5-triazine ring, for example, those described in JP-A No. 2001-166144 can be used. In addition, compounds represented by the following general formula (2) are also preferably used.

(Wherein R ₇ to R ₁₄ are each independently a hydrogen atom, an alkyl group, an alkenyl group, an aryl group or a heterocyclic group, and particularly preferably a hydrogen atom. N is an integer of 1 to 20) 2 is preferred.)
Alternatively, a compound having a porphyrin skeleton represented by the following general formula (3) can be preferably used.

(Wherein R _{15 to} R ₂₂ are each independently a hydrogen atom, a halogen atom, an alkoxy group, an alkylthio group, a substituted or unsubstituted phenoxy group, a substituted or unsubstituted naphthoxy group, a substituted or unsubstituted phenylthio group, or A substituted or unsubstituted naphthylthio group, wherein X represents a hydrogen atom, a halogen atom, an alkoxy group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted phenoxy group, and the halogen atom includes fluorine, chlorine, bromine; In addition, the alkoxy group is not particularly limited, but the alkyl group in the substituent is preferably a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms. Particularly preferred are linear, branched or cyclic alkyl groups of 1 to 8. Specific examples of substituted or unsubstituted phenyl groups Examples thereof include a phenyl group, a p-chlorophenyl group, a p-bromophenyl group, and a p-nitrophenyl group. Specific examples of the substituted or unsubstituted phenyl group include a phenoxy group and a p-chlorophenoxy group. , P-bromophenoxy group, p-nitrophenoxy group, etc. Z represents —CH— or —N—.

Examples of the halogen atom for R _{15 to} R ₂₂ include fluorine, chlorine, bromine and iodine. The alkoxy group and thioalkyl group are not particularly limited, but the alkyl group in the substituent is preferably a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, and having 1 to 8 carbon atoms. A linear, branched or cyclic alkyl group is particularly preferred.

Specific examples of the alkyl group in the alkoxy group and thioalkyl group include methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, sec-butyl group, t-butyl group. Group, n-pentyl group, iso-pentyl group, 2-methylbutyl group, 1-methylbutyl group, neo-pentyl group, 1,2-dimethylpropyl group, 1,1 dimethylpropyl group, cyclopentyl group, n-hexyl group, 4-methylpentyl group, 3methylpentyl group, 2-methylpentyl group, 1-methylpentyl group, 3,3-dimethylbutyl group, 2,3-dimethylbutyl group, 1,3-dimethylbutyl group, 2,2 -Dimethylbutyl group, 1,2-dimethylbutyl group, 1,1-dimethylbutyl group, 3-ethylbutyl group, 2-ethylbutyl group, 1-ethylbutyl Group, 1,2,2-trimethylbutyl group, 1,1,2-trimethylbutyl group, 1-ethyl-2-methylpropyl group, cyclohexyl group, n-heptyl group, 2-methylhexyl group, 3-methylhexyl Group, 4-methylhexyl group, 5 methylhexyl group, 2,4-dimethylpentyl group, n-octyl group, 2-ethylhexyl group, 2,5-dimethylhexyl group, 2,5,5-trimethylpentyl group, 2 , 4-dimethylhexyl group, 2,2,4-trimethylpentyl group, n-octyl group, 3,5,5-trimethylhexyl group, n-nonyl group, n-decyl group, 4-ethyloctyl group, 4- Ethyl 4,5-dimethylhexyl group, n-undecyl group, n-dodecyl group, 1,3,5,7-tetraethyloctyl group, 4-butyloctyl group, 6,6-diethyloctyl group Til, n-tridecyl, 6-methyl-4-butyloctyl, n-tetradecyl, n-pentadecyl, 3,5-dimethylheptyl, 2,6-dimethylheptyl, 2,4-dimethylheptyl Group, 2,2,5,5-tetramethylhexyl group, 1-cyclopentyl-2,2-dimethylpropyl group, 1-cyclohexyl-2,2-dimethylpropyl group and the like.
Specific examples of the substituted or unsubstituted phenoxy group include phenoxy group, 2-methylphenoxy group, 3-methylphenoxy group, 4-methylphenoxy group, 2-ethylphenoxy group, 3-ethylphenoxy group, 4-ethyl. Examples include phenoxy group, 2,4-dimethylphenoxy group, 3,4-dimethylphenoxy group, 4-t-butylphenoxy group, 4-aminophenoxy group, 4-dimethylaminophenoxy group, 4-diethylaminophenoxy group and the like.
Specific examples of the substituted or unsubstituted naphthoxy group include 1-naphthoxy group, 2-naphthoxy group, nitronaphthoxy group, cyanonaphthoxy group, hydroxynaphthoxy group, methylnaphthoxy group, trifluoromethylnaphthoxy group and the like. .
Specific examples of the substituted or unsubstituted phenylthio group include a phenylthio group, a 2-methylphenylthio group, a 3-methylphenylthio group, a 4-methylphenylthio group, a 2-ethylphenylthio group, and a 3-ethylphenylthio group. Group, 4-ethylphenylthio group, 2,4-dimethylphenylthio group, 3,4-dimethylphenylthio group, 4-t-butylphenylthio group, 4-aminophenylthio group, 4-dimethylaminophenylthio group , 4-diethylaminophenylthio group and the like.
Specific examples of the substituted or unsubstituted naphthylthio group include 1-naphthylthio group, 2-naphthylthio group, nitronaphthylthio group, cyanonaphthylthio group, hydroxynaphthylthio group, methylnaphthylthio group, trifluoromethylnaphthylthio group. Etc.

  Two or more kinds of compounds (for example, a compound having a 1,3,5-triazine ring and a compound having a porphyrin skeleton) may be used in combination.

  Examples of the planar structure-based epoxy compound include bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, bisphenol AD type epoxy compounds, hydrogenated bisphenol A type epoxy compounds, and the like; for example, phenol novolac type epoxy compounds , Novolak-type epoxy compounds such as cresol novolak-type epoxy compounds; for example, glycidylamine-type epoxy compounds such as tetraglycidyldiaminodiphenylmethane, triglycidyl-p-aminophenol, triglycidyl-m-aminophenol, tetraglycidyl-m-xylenediamine; For example, glycidyl ester epoxy compounds such as diglycidyl phthalate, diglycidyl hexahydrophthalate, diglycidyl tetrahydrophthalate; Examples thereof include complex epoxy compounds such as triglycidyl isocyanurate.

An example is shown in the following general formula (4).

As the polymerizable liquid crystal compound, rod-like liquid crystal molecules or discotic liquid crystal molecules can be used, and discotic liquid crystal molecules are particularly preferable. As the rod-like liquid crystal molecule, the liquid crystal molecule described in JP-A-2006-16599 can be used. Besides, for example, azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoates Cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are also used. As the discotic liquid crystalline molecules, for example, those described in JP-A-8-27284 can be used. An example is shown below.

  In the above general formula, Y is a divalent linking group selected from the group consisting of an alkylene group, an alkenylene group, an arylene group, —CO—, —NH—, —O—, —S—, and combinations thereof, and Most preferably, it is a group obtained by combining at least two of the divalent groups. The alkylene group preferably has 1 to 12 carbon atoms, the alkenylene group preferably has 2 to 12 carbon atoms, and the arylene group preferably has 6 to 10 carbon atoms. . The alkylene group, alkenylene group and arylene group may have a substituent (eg, alkyl group, halogen atom, cyano, alkoxy group, acyloxy group).

  R is an unsaturated polymerizable group (formula A, B, C, D, E, F), a functional group (formula I, J, K, L, M, N, O), a thermally polymerizable group (formula At least one crosslinkable group selected from G, H, P, Q, R, S, T, U), or an alkyl group, an alkenyl group, an aryl group, or a heterocyclic group substituted with the crosslinkable group is there.

The unsaturated polymerizable group is more preferably an ethylenically unsaturated polymerizable group (formulas A, B, C, D), and —CH ₂ NHCOCH═CH ₂ , —CH ₂ NHCO (CH ₂ ). ₇ CH═CH (CH ₂ ) ₇ CH ₃ , —OCO (C ₆ H ₄ ) O (CH ₂ ) ₆ CH═CH _{2 and the} like are also preferably used.

  Below, each component of the coloring composition used in order to form each color pixel of the color filter which concerns on this embodiment is demonstrated.

  The pigment carrier contained in the coloring composition used for forming each color pixel is for dispersing the pigment, and is composed of a transparent resin, a precursor thereof, or a mixture thereof.

  The transparent resin is a resin having a transmittance of preferably 80% or more, more preferably 95% or more in the entire wavelength region of 400 to 700 nm in the visible light region. The transparent resin includes a thermoplastic resin, a thermosetting resin, and a photosensitive resin, and its precursor includes a monomer or an oligomer that is cured by irradiation with radiation to form a transparent resin. Alternatively, two or more kinds can be mixed and used.

  The pigment carrier can be used in an amount of 30 to 700 parts by weight, preferably 60 to 450 parts by weight with respect to 100 parts by weight of the pigment in the coloring composition. When a mixture of a transparent resin and its precursor is used as a pigment carrier, the transparent resin is 20 to 400 parts by weight, preferably 50 to 250 parts by weight, based on 100 parts by weight of the pigment in the coloring composition. Can be used. The precursor of the transparent resin can be used in an amount of 10 to 300 parts by weight, preferably 10 to 200 parts by weight, with respect to 100 parts by weight of the pigment in the coloring composition.

  Examples of the thermoplastic resin include butyral resin, styrene-maleic acid copolymer, chlorinated polyethylene, chlorinated polypropylene, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyurethane resin, and polyester resin. And acrylic resins, alkyd resins, polystyrene resins, polyamide resins, rubber resins, cyclized rubber resins, celluloses, polybutadiene, polyethylene, polypropylene, polyimide resins, and the like.

  Examples of the thermosetting resin include an epoxy resin, a benzoguanamine resin, a rosin-modified maleic acid resin, a rosin-modified fumaric acid resin, a melamine resin, a urea resin, and a phenol resin.

  Examples of the photosensitive resin include (meth) acrylic compounds having a reactive substituent such as an isocyanate group, an aldehyde group, and an epoxy group on a linear polymer having a reactive substituent such as a hydroxyl group, a carboxyl group, or an amino group, A resin obtained by reacting an acid and introducing a photocrosslinkable group such as a (meth) acryloyl group or a styryl group into the linear polymer is used.

  A linear polymer containing an acid anhydride such as a styrene-maleic anhydride copolymer or an α-olefin-maleic anhydride copolymer is half-esterified with a (meth) acrylic compound having a hydroxyl group such as hydroxyalkyl (meth) acrylate. A modified version is also used.

  Monomers and oligomers that are precursors of transparent resins include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, cyclohexyl (meth) acrylate, polyethylene glycol di (meth) acrylate, pentaerythritol tri (meth) ) Acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tricyclodecanyl (meth) acrylate, melamine (meth) acrylate, various acrylic esters such as epoxy (meth) acrylate and methacrylic acid Examples thereof include esters, (meth) acrylic acid, styrene, vinyl acetate, (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, acrylonitrile and the like. These can be used alone or in admixture of two or more.

  When the composition is cured by ultraviolet irradiation, a photopolymerization initiator or the like is added to the coloring composition. Examples of the photopolymerization initiator include 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, diethoxyacetophenone, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 1- Hydroxycyclohexyl phenyl ketone, 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butane-1 Acetophenone photopolymerization initiators such as -one, benzoin photopolymerization initiators such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzyldimethyl ketal, benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4- Fe Benzophenone photopolymerization initiators such as rubenzophenone, hydroxybenzophenone, acrylated benzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone Thioxanthone photopolymerization initiators such as 2,4,6-trichloro-s-triazine, 2-phenyl-4,6-bis (trichloromethyl) -s-triazine, 2- (p-methoxyphenyl) -4, 6-bis (trichloromethyl) -s-triazine, 2- (p-tolyl) -4,6-bis (trichloromethyl) -s-triazine, 2-piperonyl-4,6-bis (trichloromethyl) -s- Triazine, 2,4-bis (trichlorome Til) -6-styryl s-triazine, 2- (naphth-1-yl) -4,6-bis (trichloromethyl) -striazine, 2- (4-methoxy-naphth-1-yl) -4,6 Initiation of triazine photopolymerization such as -bis (trichloromethyl) -s-triazine, 2,4-trichloromethyl- (piperonyl) -6-triazine, 2,4-trichloromethyl (4'-methoxystyryl) -6-triazine Agents, borate photopolymerization initiators, carbazole photopolymerization initiators, imidazole photopolymerization initiators, and the like are used.

  A photoinitiator can be used in the amount of 5-200 weight part with respect to 100 weight part of pigments in a coloring composition, Preferably it is 10-150 weight part.

  The photopolymerization initiator is used alone or in combination of two or more. As the sensitizer, α-acyloxy ester, acylphosphine oxide, methylphenylglyoxylate, benzyl, 9,10-phenanthrenequinone, Combined use of compounds such as camphorquinone, ethylanthraquinone, 4,4'-diethylisophthalophenone, 3,3 ', 4,4'-tetra (t-butylperoxycarbonyl) benzophenone, 4,4'-diethylaminobenzophenone You can also

  The sensitizer can be contained in an amount of 0.1 to 60 parts by weight with respect to 100 parts by weight of the photopolymerization initiator.

  Furthermore, the coloring composition can contain a polyfunctional thiol that functions as a chain transfer agent. The polyfunctional thiol may be a compound having two or more thiol groups. For example, hexanedithiol, decanedithiol, 1,4-butanediol bisthiopropionate, 1,4-butanediol bisthioglycolate, ethylene Glycol bisthioglycolate, ethylene glycol bisthiopropionate, trimethylolpropane tristhioglycolate, trimethylolpropane tristhiopropionate, trimethylolpropane tris (3-mercaptobutyrate), pentaerythritol tetrakisthioglycolate, Pentaerythritol tetrakisthiopropionate, tris (2-hydroxyethyl) isocyanurate, trimercaptopropionic acid, 1,4-dimethylmercaptobenzene, 2,4,6-trimerca DOO -s- triazine, 2- (N, N- dibutylamino) -4,6-dimercapto -s- triazine. These polyfunctional thiols can be used alone or in combination.

  The polyfunctional thiol can be used in an amount of 0.2 to 150 parts by weight, preferably 0.2 to 100 parts by weight, with respect to 100 parts by weight of the pigment in the coloring composition.

  Furthermore, in order to easily disperse the pigment in the pigment carrier and to apply a dry film thickness of 0.2 to 5 μm on a transparent substrate such as a glass substrate to form a filter segment, A solvent can be contained. Examples of the solvent include cyclohexanone, ethyl cellosolve acetate, butyl cellosolve acetate, 1-methoxy-2-propyl acetate, diethylene glycol dimethyl ether, ethylbenzene, ethylene glycol diethyl ether, xylene, ethyl cellosolve, methyl-n amyl ketone, propylene glycol monomethyl ether, toluene, Examples include methyl ethyl ketone, ethyl acetate, methanol, ethanol, isopropyl alcohol, butanol, isobutyl ketone, petroleum solvent, and the like. These can be used alone or in combination.

The solvent can be used in an amount of 800 to 4000 parts by weight, preferably 1000 to 2500 parts by weight with respect to 100 parts by weight of the pigment in the coloring composition.
The coloring composition comprises one or more pigments, if necessary, together with the above photopolymerization initiator, in a pigment carrier and an organic solvent, such as a three roll mill, a two roll mill, a sand mill, a kneader, and an attritor. It can be prepared using a dispersing means. Moreover, the coloring composition containing 2 or more types of pigments can also be prepared by mixing each pigment separately finely dispersed in a pigment carrier and an organic solvent.

  When the pigment is dispersed in the pigment carrier and the organic solvent, a dispersion aid such as a resin-type pigment dispersant, a surfactant, or a pigment derivative can be appropriately contained.

  Since the dispersion aid is excellent in dispersibility of the pigment and has a great effect of preventing re-aggregation of the pigment after dispersion, a coloring composition obtained by dispersing the pigment in a pigment carrier and an organic solvent using the dispersion aid is used. When used, a color filter excellent in transparency can be obtained.

  The dispersion aid can be used in an amount of 0.1 to 40 parts by weight, preferably 0.1 to 30 parts by weight with respect to 100 parts by weight of the pigment in the coloring composition.

  The resin-type pigment dispersant has a pigment-affinity part that has the property of adsorbing to the pigment and a part that is compatible with the pigment carrier, and adsorbs to the pigment to stabilize the dispersion of the pigment on the pigment carrier. It works.

  Specific examples of resin-type pigment dispersants include polyurethanes, polycarboxylic acid esters such as polyacrylates, unsaturated polyamides, polycarboxylic acids, polycarboxylic acid (partial) amine salts, polycarboxylic acid ammonium salts, and polycarboxylic acid alkyls. Amine salts, polysiloxanes, long-chain polyaminoamide phosphates, hydroxyl group-containing polycarboxylic acid esters, their modified products, amides formed by the reaction of poly (lower alkylene imines) and polyesters having free carboxyl groups, Oil-based dispersants such as salts, (meth) acrylic acid-styrene copolymers, (meth) acrylic acid- (meth) acrylic ester copolymers, styrene-maleic acid copolymers, polyvinyl alcohol, polyvinylpyrrolidone, etc. Water-soluble resin, water-soluble polymer compound, polyester , Modified polyacrylate, ethylene oxide / propylene oxide addition compound, phosphate ester-based and the like are used, they can be used alone or in admixture of two or more.

  Surfactants include polyoxyethylene alkyl ether sulfate, sodium dodecylbenzenesulfonate, alkali salt of styrene-acrylic acid copolymer, sodium alkylnaphthalenesulfonate, sodium alkyldiphenyletherdisulfonate, lauryl sulfate monoethanolamine, lauryl Anionic surfactants such as triethanolamine sulfate, ammonium lauryl sulfate, monoethanolamine stearate, sodium stearate, sodium lauryl sulfate, monoethanolamine of styrene-acrylic acid copolymer, polyoxyethylene alkyl ether phosphate; Polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene Nonionic surfactants such as alkyl ether phosphates, polyoxyethylene sorbitan monostearate, and polyethylene glycol monolaurate; chaotic surfactants such as alkyl quaternary ammonium salts and their ethylene oxide adducts; alkyldimethylamino Examples include amphoteric surfactants such as alkylbetaines such as betaine acetate and alkylimidazolines, and these can be used alone or in admixture of two or more.

  The dye derivative is a compound in which a substituent is introduced into an organic dye, and is preferably close to the hue of the pigment to be used. However, if the addition amount is small, those having different hues may be used. Organic dyes also include light yellow aromatic polycyclic compounds such as naphthalene and anthraquinone that are not generally called dyes.

  Examples of the dye derivatives are described in JP-A-63-305173, JP-B-57-15620, JP-B-59-40172, JP-B-63-17102, JP-B-5-9469, and the like. You can use what you have.

  In particular, a pigment derivative having a basic group is preferably used because it has a large pigment dispersion effect. These can be used alone or in admixture of two or more.

  The coloring composition can contain a storage stabilizer in order to stabilize the viscosity with time of the composition. Examples of storage stabilizers include quaternary ammonium chlorides such as benzyltrimethyl chloride and diethylhydroxyamine, organic acids such as lactic acid and oxalic acid, and organic acids such as methyl ether, t-butylpyrocatechol, tetraethylphosphine, and tetraphenylphosphine. Examples thereof include phosphine and phosphite.

  The storage stabilizer can be contained in an amount of 0.1 to 10 parts by weight with respect to 100 parts by weight of the pigment in the coloring composition.

  In addition, the coloring composition may contain an adhesion improving agent such as a silane coupling agent in order to improve the adhesion to the substrate. Examples of the silane coupling agent include vinyl silanes such as vinyltris (β-methoxyethoxy) silane, vinylethoxysilane, and vinyltrimethoxysilane, (meth) acrylsilanes such as γ-methacryloxypropyltrimethoxysilane, β- (3 , 4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) methyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane, β- (3,4-epoxycyclohexyl) ) Epoxysilanes such as methyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β ( Aminoethyl) γ-aminopro Lutriethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldiethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N Examples include aminosilanes such as -phenyl-γ-aminopropyltriethoxysilane, thiosilanes such as γ-mercaptopropyltrimethoxysilane, and γ-mercaptopropyltriethoxysilane.

  The silane coupling agent can be contained in an amount of 0.01 to 100 parts by weight with respect to 100 parts by weight of the pigment in the coloring composition.

  The coloring composition can be prepared in the form of gravure offset printing ink, waterless offset printing ink, inkjet ink, silk screen printing ink, solvent development type or alkali development type color resist. The colored resist is obtained by dispersing a dye in a composition containing a thermoplastic resin, a thermosetting resin or a photosensitive resin, a monomer, a photopolymerization initiator, and an organic solvent.

  The pigment is preferably contained in a proportion of 5 to 70% by weight based on the total solid content of the colored composition (100% by weight). More preferably, it is contained in a proportion of 20 to 50% by weight, and the remainder consists essentially of a resinous binder provided by a pigment carrier.

  The colored composition is removed by means of centrifugal separation, sintering filter, membrane filter, etc. to remove coarse particles of 5 μm or more, preferably coarse particles of 1 μm or more, more preferably 0.5 μm or more and coarse particles It is preferable to carry out.

  The red pixel, the green pixel, and the blue pixel in the color filter are formed on the transparent substrate using the above-described colored compositions by a printing method or a photolithography method.

  As the transparent substrate, glass plates such as soda lime glass, low alkali borosilicate glass and non-alkali alumino borosilicate glass, and resin plates such as polycarbonate, polymethyl methacrylate, and polyethylene terephthalate are used. In addition, a transparent electrode made of a combination of metal oxides such as indium oxide, tin oxide, zinc oxide and antimony oxide is formed on the surface of the glass plate or resin plate for driving the liquid crystal after the liquid crystal panel is formed. Also good.

  The formation of each color filter segment by the printing method can be patterned simply by repeating the printing and drying of the colored composition prepared as the above various printing inks. Therefore, the color filter manufacturing method is low-cost and excellent in mass productivity. ing. Furthermore, it is possible to print a fine pattern having high dimensional accuracy and smoothness by the development of printing technology. In order to perform printing, it is preferable that the ink does not dry and solidify on the printing plate or on the blanket. Control of ink fluidity on a printing press is also important, and ink viscosity can be adjusted with a dispersant or extender pigment.

  The ink jet method is a method in which an ink jet apparatus having a plurality of fine discharge ports (ink jet heads) for each color is directly printed on a transparent substrate or a substrate on which an active element such as a TFT is formed.

  When each color pixel is formed by a photolithography method, the coloring composition prepared as the solvent developing type or alkali developing type coloring resist is applied to a transparent substrate by spray coating, spin coating, slit coating, roll coating, or the like. To apply a dry film thickness of 0.2 to 10 μm.

  When drying the coating film, a vacuum dryer, a convection oven, an IR oven, a hot plate, or the like may be used.

  If necessary, the dried film is exposed to ultraviolet light through a mask having a predetermined pattern provided in contact with or non-contact with the film.

  Then, after immersing in a solvent or alkali developer or spraying the developer by spraying or the like to remove the uncured portion to form a desired pattern, the same operation is repeated for other colors to produce a color filter. be able to.

  Furthermore, in order to accelerate the polymerization of the colored resist, heating can be performed as necessary.

According to the photolithography method, a color filter with higher accuracy than the printing method can be manufactured.

  In development, an aqueous solution such as sodium carbonate or sodium hydroxide is used as an alkali developer, and an organic alkali such as dimethylbenzylamine or triethanolamine can also be used. Moreover, an antifoamer and surfactant can also be added to a developing solution. As a development processing method, a shower development method, a spray development method, a dip (immersion) development method, a paddle (liquid accumulation) development method, or the like can be applied.

  In order to increase the UV exposure sensitivity, the colored resist is applied and dried, and then a water-soluble or alkaline water-soluble resin such as polyvinyl alcohol or a water-soluble acrylic resin is applied and dried to inhibit polymerization inhibition by oxygen. Ultraviolet exposure can also be performed after the film to be prevented is formed.

  A color filter suitable for use in the liquid crystal display device according to the present embodiment can be produced by an electrodeposition method, a transfer method, an ink jet method, or the like in addition to the above method.

  The electrodeposition method is a method for producing a color filter by using a transparent conductive film formed on a transparent substrate and forming each color filter segment on the transparent conductive film by electrophoresis of colloidal particles. is there.

  The transfer method is a method in which a color filter layer is formed in advance on the surface of a peelable transfer base sheet, and this color filter layer is transferred to a desired transparent substrate.

Next, a liquid crystal display device including the color filter described above will be described.
FIG. 2 is a schematic cross-sectional view of a liquid crystal display device according to an embodiment of the present invention. A device 4 shown in FIG. 2 is a typical example of a TFT drive type liquid crystal display device for a liquid crystal TV, and includes a pair of transparent substrates 5 and 6 disposed so as to face each other. LC) is enclosed.

The liquid crystal (LC) is aligned according to liquid crystal alignment modes such as TN (Twisted Nematic), STN (Super Twisted Nematic), IPS (In-Plane switching), VA (Vertical Alignment), OCB (Optically Compensated Birefringence), etc. .

  A TFT (thin film transistor) array 7 is formed on the inner surface of the first transparent substrate 5, and a transparent electrode layer 8 made of, for example, ITO is formed thereon. An alignment layer 9 is provided on the transparent electrode layer 8. Further, on the outer surface of the transparent substrate 5, a polarizing plate 10 including a retardation film is formed.

  On the other hand, a color filter 11 is formed on the inner surface of the second transparent substrate 6. The red, green and blue filter segments constituting the color filter 11 are separated by a black matrix (not shown).

  A transparent protective film (not shown) is formed so as to cover the color filter 11, and further, a transparent electrode layer 12 made of, for example, ITO is formed on the color filter 11, and the alignment layer 13 covers the transparent electrode layer 12. Is provided. A polarizing plate 14 is formed on the outer surface of the transparent substrate 6.

  A backlight unit 16 including a three-wavelength lamp 15 is provided below the polarizing plate 10.

  As described above, according to the present embodiment, in order to obtain a color filter with higher contrast, the type of pigment to be used is specified, or the red, green, and Even if the thickness direction retardation value of the blue colored pixel layer may be positive or / and discontinuous, a pigment that can have a negative thickness direction retardation is selected or negative. By performing fine processing, and by adding fine particles that can be adjusted to a negative thickness direction retardation, the thickness direction retardation value can be adjusted to an optimum value so as to be negative and continuous. A colored composition for a color filter can be provided.

  Furthermore, according to another embodiment of the present invention, a liquid crystal display was manufactured using the above-described color filter so as to be suitable for the optical characteristics of the optical compensation layer and other components, particularly the wavelength dispersion characteristics of retardation. In this case, since the polarization state of the light passing through the display area of each colored pixel does not vary, a liquid crystal display device excellent in viewing angle display from an oblique direction can be obtained.

  Furthermore, since the display is black with the viewing angle compensated from the oblique direction, the color shift can be reduced and neutral black can be reproduced when viewed from the oblique direction, and the display characteristics are excellent. Can do.

  Hereinafter, although an example is given and described about an embodiment of the present invention, the present invention is not limited to these examples. In addition, since the material used in the present invention is extremely sensitive to light, it is necessary to prevent exposure to unnecessary light such as natural light, and it goes without saying that all operations are performed under a yellow or red light. In the examples and comparative examples, “parts” means “parts by weight”.

  The symbol of the pigment indicates a color index number. For example, “PR254” represents “CI Pigment Red 254” and “PY150” represents “CI Pigment Yellow 150”.

The dye derivatives used in the following examples are shown in Table 1 below.

a) Production of refined pigments The refined pigments used in Examples and Comparative Examples were produced by the following method. And the average primary particle diameter of the obtained pigment was measured by a general method for directly measuring the size of primary particles from an electron micrograph.

  Specifically, the particles in the field of view are photographed with a transmission electron microscope JEM-2010 (manufactured by JEOL Ltd.), and the minor axis diameters of the primary particles of the individual pigments constituting the aggregate on the two-dimensional image The major axis diameter was measured, and the average was taken as the particle diameter of the pigment particles. Next, for 100 or more pigment particles, the volume (weight) of each particle was obtained by approximating the obtained particle size to a rectangular parallelepiped, and the volume average particle size was defined as the average primary particle size.

  At this time, the colored composition as a sample is ultrasonically dispersed in a solvent, and then the particles are photographed with the microscope. The same result can be obtained by using either a transmission type (TEM) or a scanning type (SEM). The primary particle diameter referred to here represents a particle diameter (equivalent circle diameter) corresponding to 50% of the total amount in the cumulative curve of the number particle size distribution.

[Production Example 1]
100 parts of diketopyrrolopyrrole red pigment PR254 ("Irgafoa Red B-CF" manufactured by Ciba Specialty Chemicals; R-1), 18 parts of dye derivative (D-1), 1000 parts of crushed salt, and 120 parts of diethylene glycol Was charged into a stainless steel 1 gallon kneader (manufactured by Inoue Seisakusho) and kneaded at 60 ° C. for 10 hours.

  The mixture was added to 2000 parts of warm water, heated to about 80 ° C. and stirred with a high speed mixer for about 1 hour to form a slurry, filtered and washed repeatedly to remove salt and solvent, and then at 80 ° C. for 24 hours. Dried to obtain 115 parts of salt milled pigment (R-2). The primary particle diameter of the obtained pigment is shown in Table 2 below.

[Production Example 2]
100 parts of anthraquinone red pigment PR177 (“Chromophthal Red A2B” manufactured by Ciba Specialty Chemicals), 8 parts of a dye derivative (D-2), 700 parts of crushed salt, and 180 parts of diethylene glycol are made of 1 gallon kneader made of stainless steel (Inoue Manufacturing Co., Ltd.) And kneaded at 70 ° C. for 4 hours.

  The mixture was put into 4000 parts of warm water, heated to about 80 ° C., stirred with a high speed mixer for about 1 hour to form a slurry, filtered and washed with water to remove salt and solvent, and then at 80 ° C. for 24 hours. Dried to obtain 102 parts of a salt milled pigment (R-3). The primary particle diameter of the obtained pigment is shown in Table 2 below.

[Production Example 3]
A sulfonation flask is charged with 170 parts of tert-amyl alcohol under a nitrogen atmosphere. Then 11.04 parts of sodium are added and the mixture is heated to 92-102 ° C. The molten sodium is then kept at 100-107 ° C. overnight with vigorous stirring. A solution prepared by dissolving 44.2 parts of 4-chlorobenzonitrile and 37.2 parts of diisopropyl succinate in 50 parts of tert-amyl alcohol at 80 to 98 ° C. was dissolved in the obtained solution. Introduce over 2 hours.

  After the introduction, the reaction mixture is stirred for a further 3 hours at 80 ° C. and at the same time 4.88 parts of diisopropyl succinate are added dropwise. The reaction mixture is cooled to room temperature and added to a 20 ° C. mixture of 270 parts of methanol, 200 parts of water, and 48.1 parts of concentrated sulfuric acid and stirring is continued at 20 ° C. for 6 hours.

  The red mixture was filtered, and the residue was washed with methanol and water, and then dried at 80 ° C. to obtain 46.7 parts of a red pigment (R-4). The primary particle diameter of the obtained pigment is shown in Table 2 below.

[Production Example 4]
120 parts of halogenated copper phthalocyanine-based green pigment PG36 (“Rionol Green 6YK” manufactured by Toyo Ink Manufacturing Co., Ltd.), 1600 parts of crushed sodium chloride, and 270 parts of diethylene glycol were charged into a 1 gallon kneader (manufactured by Inoue Seisakusho) at 70 ° C. And kneaded for 12 hours. The mixture was poured into 5000 parts of warm water, stirred at a high speed mixer for about 1 hour while being heated to about 70 ° C. to form a slurry, filtered and washed repeatedly to remove salt and solvent, and then at 80 ° C. for 24 hours. It dried and obtained 117 parts of salt milling pigment (G-1).

  The primary particle diameter of the obtained pigment is shown in Table 2 below.

[Production Example 5]
In a molten salt of 200 ° C. of 356 parts of aluminum chloride and 6 parts of sodium chloride, 46 parts of zinc phthalocyanine was dissolved, cooled to 130 ° C., and stirred for 1 hour. The reaction temperature was raised to 180 ° C., and bromine was added dropwise at 10 parts per hour for 10 hours. Thereafter, chlorine was introduced at 0.8 parts per hour for 5 hours.

  The reaction solution was gradually poured into 3200 parts of water, then filtered and washed with water to obtain 107.8 parts of a crude zinc halide phthalocyanine pigment. The average number of bromine contained in one molecule of the crude zinc halide phthalocyanine pigment was 14.1 and the average number of chlorine was 1.9.

  120 parts of the obtained crude zinc halide phthalocyanine pigment, 1600 parts of crushed salt and 270 parts of diethylene glycol were charged into a stainless steel 1 gallon kneader (manufactured by Inoue Seisakusho) and kneaded at 70 ° C. for 12 hours. The mixture was poured into 5000 parts of warm water, stirred at a high speed mixer for about 1 hour while being heated to about 70 ° C. to form a slurry, filtered and washed repeatedly to remove salt and solvent, and then at 80 ° C. for 24 hours. It dried and obtained 117 parts of salt milling process pigments (G-2).

  The primary particle diameter of the obtained pigment is shown in Table 2 below.

[Production Example 6]
A separable flask was charged with 150 parts of water, and 63 parts of 35% hydrochloric acid was added with stirring to prepare a hydrochloric acid solution. To this hydrochloric acid solution, 38.7 parts of benzenesulfonyl hydrazide was added while paying attention to foaming, and ice was added until the liquid temperature became 0 ° C. or lower. After cooling, 19 parts of sodium nitrite was added over 30 minutes, stirred for 30 minutes at 0-15 ° C., and sulfamic acid was added until no coloration was observed on potassium iodide starch paper.

  Subsequently, after adding 25.6 parts of barbituric acid, it heated up to 55 degreeC and stirred as it was for 2 hours. Further, 25.6 parts of barbituric acid was added, and after raising the temperature to 80 ° C., sodium hydroxide was added until the pH reached 5.

  Next, after stirring at 80 ° C. for 3 hours, the temperature was lowered to 70 ° C., followed by filtration and washing with warm water. The obtained press cake was reslurried in 1200 parts of warm water, and then stirred at 80 ° C. for 2 hours. Thereafter, filtration was performed at the same temperature, and washing with 2000 parts of water at 80 ° C. was performed with warm water, and it was confirmed that benzenephonamide was transferred to the filtrate side. The obtained press cake was dried at 80 ° C. to obtain 61.0 parts of disodium azobarbituric acid.

  Next, 200 parts of water was placed in a separable flask, and 8.1 parts of the obtained disodium azobarbituric acid powder was added and dispersed while stirring. After uniformly dispersing, the temperature of the solution was raised to 95 ° C., and 5.7 parts of melamine and 1.0 part of diallylaminomelamine were added.

  Further, a green solution obtained by dissolving 6.3 parts of cobalt (II) chloride hexahydrate in 30 parts of water was added dropwise over 30 minutes. After completion of the dropping, complexation was performed at 90 ° C. for 1.5 hours. Thereafter, the pH was adjusted to 5.5, 20.4 parts of xylene, 0.4 part of sodium oleate, and 16 parts of water were previously stirred to add 20.4 parts of an emulsion, and further heated for 4 hours. Stir.

  After cooling to 70 ° C., it was quickly filtered, and washing with warm water at 70 ° C. was repeated until the inorganic salt could be washed. Thereafter, 14 parts of an azo yellow pigment (Y-2) was obtained through drying and pulverization steps.

  The primary particle diameter of the obtained pigment is shown in Table 2 below.

[Production Example 7]
160 parts of yellow pigment (CI Pigment Yellow 138, “PALIOTOL YELLOW K0961HD” manufactured by BASF), 1600 parts of sodium chloride, and 270 parts of diethylene glycol (manufactured by Tokyo Kasei Co., Ltd.) were charged into a 1 gallon kneader (manufactured by Inoue Seisakusho) made of stainless steel. It knead | mixed for 15 hours at 60 degreeC.

  Next, this mixture is poured into about 5 liters of warm water, heated to about 70 ° C. and stirred with a high speed mixer for about 1 hour to form a slurry, then filtered and washed to remove sodium chloride and diethylene glycol, It was dried at 80 ° C. for 24 hours to obtain 157 parts of salt milled pigment (Y-3).

  The primary particle diameter of the obtained pigment is shown in Table 2 below.

[Production Example 8]
100 parts of copper phthalocyanine blue pigment PB15: 6 (“Rionol Blue ES” manufactured by Toyo Ink Manufacturing Co., Ltd.), 800 parts of crushed salt, and 100 parts of diethylene glycol were charged into a stainless steel 1 gallon kneader (manufactured by Inoue Seisakusho) at 70 ° C. And kneaded for 12 hours.

  The mixture was poured into 3000 parts of warm water, stirred at a high speed mixer for about 1 hour while being heated to about 70 ° C. to form a slurry, filtered and washed repeatedly to remove salt and solvent, and then at 80 ° C. for 24 hours. It dried and obtained 98 parts of salt milling pigment (B-1).

The primary particle diameter of the obtained pigment is shown in Table 2 below.

  “FANCHON FAST YELLOW Y-5688” (C.I. Pigment Yellow 150) manufactured by BAYER is used as yellow pigment 1.

b) Preparation of acrylic resin solution
800 parts of cyclohexanone is placed in a reaction vessel, heated to 100 ° C. while injecting nitrogen gas into the vessel, and a mixture of the following monomer and thermal polymerization initiator is added dropwise over 1 hour at the same temperature to conduct a polymerization reaction. It was.

60.0 parts of styrene
Methacrylic acid 60.0 parts
Methyl methacrylate 65.0 parts
65.0 parts butyl methacrylate
Azobisisobutyronitrile 10.0 parts dropwise, then reacted at 100 ° C. for 3 hours, and 2.0 parts of azobisisobutyronitrile dissolved in 50 parts of cyclohexanone was added. The reaction was continued for a time to synthesize a resin solution.

  After cooling to room temperature, about 2 g of the resin solution was sampled, heated and dried at 180 ° C. for 20 minutes to measure the nonvolatile content, and cyclohexanone was added to the previously synthesized resin solution so that the nonvolatile content was 20%. An acrylic resin solution was prepared.

c) Preparation of Pigment Dispersion Mixtures with the composition (weight ratio) shown in Table 3 below were uniformly stirred and mixed, then dispersed with a zirconia bead having a diameter of 1 mm for 5 hours with a sand mill, and then filtered with a 5 μm filter. Thus, each color pigment dispersion was obtained.

d) Retardation adjuster
The following commercially available compounds were used as retardation adjusting agents.

Melamine compound ・ ・ ・ Nippon Carbide Industries (trade name Nikarak MX-750)
Polymerizable liquid crystal (LC): Compound shown below

e) Preparation of colored composition (hereinafter referred to as resist) A mixture of compositions (weight ratio) shown in Table 4 below was uniformly stirred and mixed, and then filtered through a 1 μm filter to obtain each color resist.

f) Preparation of each color coating film Each color resist shown in the following Table 4 was applied to a glass substrate by spin coating, and then pre-baked at 70 ° C. for 20 minutes in a clean oven. Next, the substrate was cooled to room temperature, and then exposed to ultraviolet rays using an ultrahigh pressure mercury lamp. Thereafter, the substrate was spray-developed using a sodium carbonate aqueous solution at 23 ° C., washed with ion-exchanged water, and air-dried.

  Thereafter, post-baking was performed at 230 ° C. for 30 minutes in a clean oven to obtain each color coating film. The film thickness of the dried coating film was 2.0 μm in all cases.

g) Measurement of chromaticity, spectral transmittance, thickness direction retardation value and contrast of each color coating film
[Chromaticity, spectral transmittance]
The chromaticity in the XYZ color system chromaticity diagram was measured using a spectrophotometer ("OSP-200" manufactured by Olympus).

  Table 5 below shows the chromaticity of each color coating film prepared from each color resist shown in Table 4 above.

[Thickness direction retardation value Rth]
Thickness direction retardation value is in the range of 400 nm to 700 nm from a direction inclined 45 ° from the normal direction of the substrate on which the coating film is formed using a transmission spectroscopic ellipsometer (“M-220” manufactured by JASCO Corporation). Measurements were made at a wavelength of every 5 nm to obtain an ellipso parameter δ.

  Δ = δ / 360 × λ is used to calculate a retardation value Δ (λ), and using this value, a three-dimensional refractive index is calculated. From the above equation (8), the thickness direction retardation value (Rth) is calculated. Calculated. However, measurement was performed at a wavelength of 610 nm for a red colored pixel, 550 nm for a green colored pixel, and 450 nm for a blue colored pixel.

Rth = {(Nx + Ny) / 2−Nz} × d (8)
(Where Nx is the refractive index in the x direction in the plane of the colored pixel layer, Ny is the refractive index in the y direction in the plane of the colored pixel layer, and Nz is the refractive index in the thickness direction of the colored pixel layer. There is a slow axis where Nx is Nx ≧ Ny, and d is the thickness (nm) of the colored pixel layer.
The thickness direction retardation value Rth of each color coating film produced from each color resist shown in Table 4 is shown in Table 5 below.

[contrast]
A polarizing plate was placed on both sides of the substrate on which the coating film was formed, and the ratio of luminance (Lp) when the polarizing plate was parallel and luminance (Lc) when it was orthogonal, Lp / Lc was calculated as contrast (C). Further, the contrast of only the substrate without colored pixels = Lp / Lc is CS, CR is a red pixel, CG is a green pixel, and CB is a blue pixel.

  The luminance was measured using a color luminance meter (“BM-5A” manufactured by Topcon Corporation) under the condition of a 2 ° visual field, and “NPF-SEG1224DU” manufactured by Nitto Denko Corporation was used as the polarizing plate.

Table 5 below shows the contrast of each color coating film prepared from each color resist shown in Table 4 above.

h) Production of color filter A color filter was produced by the method shown below by combining the color resists shown in Table 4 above.

[Example 1]
First, a red resist (RR-3) was applied to a glass substrate on which a black matrix had been formed in advance by spin coating, and then prebaked at 70 ° C. for 20 minutes in a clean oven. Next, the substrate was cooled to room temperature, and then exposed to ultraviolet rays through a photomask using an ultrahigh pressure mercury lamp.

  Thereafter, the substrate was spray-developed using a sodium carbonate aqueous solution at 23 ° C., washed with ion-exchanged water, and air-dried. Further, post-baking was performed at 230 ° C. for 30 minutes in a clean oven to form striped red pixels on the substrate.

  Similarly, a green resist (GR-2) was used to form a green pixel, a blue resist (BR-1) was used to form a blue pixel, and a color filter was obtained.

  The formed film thickness of each color pixel was 2.0 μm.

i) Production of liquid crystal display device
An overcoat layer was formed on the obtained color filter, a polyimide alignment layer was formed thereon, and a rubbing treatment was performed. A polarizing plate was formed on the other surface of the glass substrate. On the other hand, a TFT array and a pixel electrode were formed on one surface of another (second) glass substrate, and a polarizing plate was formed on the other surface.

  The two glass substrates thus prepared face each other so that the electrode layers face each other, and are aligned using spacer beads while keeping the distance between both substrates constant, and the periphery is left so as to leave an opening for injecting the liquid crystal composition. Sealed with a sealant. And the liquid crystal composition for IPS was inject | poured from the opening part, and the opening part was sealed.

  The polarizing plate was provided with an optical compensation layer that was optimized so that a wide viewing angle display was possible. The thickness direction retardation value of this optical compensation layer was 37 μm at 450 nm (Rth (B)), 42 μm at 550 nm (Rth (G)), and 51 μm at 630 nm (Rth (R)). .

  The liquid crystal display device thus fabricated was combined with a backlight unit to obtain an IPS display mode liquid crystal panel.

[Example 2]
A liquid crystal display device was obtained in the same manner as in Example 1 except that the blue resist was changed from (BR-1) to (BR-2).

[Example 3]
A liquid crystal display device was obtained in the same manner as in Example 1 except that the green resist was changed from (GR-2) to (GR-3).

[Example 4]
A liquid crystal display device was obtained in the same manner as in Example 1 except that the green resist was changed from (GR-2) to (GR-3) and the blue resist was changed from (BR-1) to (BR-2). .

[Comparative Example 1]
A liquid crystal display device was obtained in the same manner as in Example 1 except that the red resist was changed from (RR-3) to (RR-1) and the blue resist was changed from (BR-1) to (BR-3). .
[Comparative Example 2]
Other than changing the red resist from (RR-3) to (RR-2), the green resist from (GR-2) to (GR-1), and the blue resist from (BR-1) to (BR-3) Obtained a liquid crystal display device in the same manner as in Example 1.
[Comparative Example 3]
A liquid crystal display device was obtained in the same manner as in Example 1 except that the green resist was changed from (GR-2) to (GR-1).

j) Visibility evaluation at the time of black display of the liquid crystal display device The produced liquid crystal display device is displayed in black and leaks from the normal direction (substantially vertical direction) of the liquid crystal panel and from the direction (oblique) inclined 45 ° from the normal direction. The amount of light (orthogonal transmitted light; leakage light) was visually observed.

  The evaluation rank of visibility at the time of black display is as follows.

◎: Excellent ○: Good ×: Inferior In addition, chromaticity (u (⊥), v (⊥)) when viewed from a substantially vertical direction during black display and 45 ° from the normal direction of the display surface The chromaticity (u (45), v (45)) when viewed from an inclined direction was measured with BM-5A manufactured by Topcon Corporation, and the color difference Δu′v ′ was calculated.

The results are shown in Table 6 below.

  As shown in Table 6 above, in the liquid crystal display devices according to Examples 1 to 4, since the color difference Δu′v ′ is less than 0.02, the visibility in the oblique direction is good.

  Moreover, in the liquid crystal display device provided with the color filter obtained from Examples 1 and 2, a high contrast in the front is achieved, so that a liquid crystal display device having particularly good visibility in the front direction can be obtained.

  On the other hand, in the liquid crystal display devices according to Comparative Examples 1 to 3, since the color difference Δu′v ′ is larger than 0.02, the visibility in the front direction or the oblique direction is poor.

It is a schematic sectional drawing which shows the color filter which concerns on one embodiment of this invention. It is a schematic sectional drawing which shows an example of the liquid crystal display device provided with the color filter of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Glass substrate, 2 ... Black matrix, 3 ... Colored pixel, 4 ... Liquid crystal display device 5, 6 ... Transparent substrate, 7 ... TFT array, 8, 12, ... Transparent electrodes 9, 13 ... orientation layers 10, 14 ... polarizing plates, 11 ... color filters, 15 ... three-wavelength lamps, 16 ... backlight units

Claims (3)

A liquid crystal display device comprising a color filter including a red display pixel, a green display pixel, and a blue display pixel on a substrate and an optical compensation layer disposed inside two polarizing plates. When the chromaticity (u, y) expressed in the CIE 1960 color system is measured, the chromaticity (u (⊥), v (⊥)) viewed from a substantially vertical direction and the normal direction of the display surface The chromaticity difference Δuv of the chromaticity (u (45), v (45)) when viewed from an azimuth inclined by 45 ° from the angle satisfies the following formula (1) :
The thickness direction retardation value RRth of the red display pixel, the thickness direction retardation value GRth of the green display pixel, and the thickness direction retardation value BRth of the blue display pixel of the color filter are expressed by the following equations (2) to (4). A liquid crystal display device characterized by being an IPS system .
Δuv = [{u (⊥) −u (45)} ² + {v (⊥) −v (45)} ² ] ^1/2 <0.02 (1)
RRth <0 (2)
GRth <0 (3)
BRth> 0 (4)
(In the formula, RRth, GRth, and BRth respectively represent numerical values obtained from the product of the value obtained by subtracting the refractive index in the thickness direction from the average in-plane refractive index of each pixel and the thickness (nm) of the pixel.) The thickness direction retardation value RRth of the red display pixel of the color filter, the thickness direction retardation value GRth of the green display pixel, and the thickness direction retardation value BRth of the blue display pixel, and the thickness direction position in the red region of the optical compensation layer. The retardation value Rth (R), the thickness direction retardation value Rth (G) in the green region, and the thickness direction retardation value Rth (B) in the blue region satisfy the following formulas (5) to (7): The liquid crystal display device according to claim 1 .
| RRth + Rth (R) | <30 (5)
| GRth + Rth (G) | <35 (6)
| BRth + Rth (B) |> 40 (7) The liquid crystal display device according to claim 1, wherein the optical compensation layer is a transparent protective film made of triacetyl cellulose (TAC).

Images