WO2018216605A1

WO2018216605A1 - Liquid crystal composition, liquid crystal display device, and production method for liquid crystal display device

Info

Publication number: WO2018216605A1
Application number: PCT/JP2018/019223
Authority: WO
Inventors: 真伸水▲崎▼; 博司土屋
Original assignee: シャープ株式会社
Priority date: 2017-05-25
Filing date: 2018-05-18
Publication date: 2018-11-29

Abstract

The present invention provides a liquid crystal composition and liquid crystal display device which can have increased contrast, and a liquid crystal display device production method capable of producing such a liquid crystal display device. The liquid crystal display device according to the present invention is provided with: a liquid crystal layer containing a liquid crystal material; a sealing material disposed so as to surround the liquid crystal layer as viewed from above; a pair of substrates sandwiching the liquid crystal layer; and an alignment control layer disposed in a region surrounded by the sealing material as viewed from above, and disposed in contact with the liquid crystal layer, wherein the alignment control layer allows a liquid crystal compound in the liquid crystal material to align in a direction perpendicular or parallel to the substrate surface, and contains a polymer obtained by polymerization of at least one type of monomer, and the at least one type of monomer includes at least one type of monomer having a cinnamate group.

Description

Liquid crystal composition, liquid crystal display device, and method of manufacturing liquid crystal display device

The present invention relates to a liquid crystal composition, a liquid crystal display device, and a method for manufacturing a liquid crystal display device. More specifically, the present invention relates to a liquid crystal composition capable of forming an alignment control layer, a liquid crystal display device having the alignment control layer, and a manufacturing method thereof.

A liquid crystal display device is a display device that uses a liquid crystal composition for display. A typical display method is to irradiate light from a backlight onto a liquid crystal panel in which the liquid crystal composition is sealed between a pair of substrates. The amount of light transmitted through the liquid crystal panel is controlled by applying a voltage to the liquid crystal composition to change the orientation of the liquid crystal material. Such a liquid crystal display device has features such as thinness, light weight, and low power consumption, and thus is used in electronic devices such as smartphones, tablet PCs, and car navigation systems.

In addition, as a display method of a liquid crystal display device, a horizontal electric field type display in which the orientation of the liquid crystal material is controlled mainly in a plane parallel to the substrate surface for the purpose of easily obtaining a wide viewing angle characteristic. The mode is attracting attention. Examples of the horizontal electric field type display mode include an in-plane switching (IPS) mode and a fringe electric field switching (FFS) mode.

In a liquid crystal display device, the alignment of a liquid crystal material in a state where no voltage is applied is generally controlled by an alignment film subjected to an alignment process. The alignment film is formed, for example, by applying an alignment film material such as polyamic acid on a substrate and then baking it. As another method for controlling the alignment of the liquid crystal material, a polymer-supported alignment technique (Polymer) that polymerizes a polymerizable monomer added in the liquid crystal layer to form a polymer layer for controlling the alignment of the liquid crystal material on the surface of the alignment film. Sustained alignment (hereinafter also referred to as PSA technology) has been studied (see, for example, Patent Documents 1 to 3). Furthermore, it has been studied to control the alignment of the liquid crystal material by the polymer layer without forming a conventional alignment film (see, for example, Patent Documents 1 and 2).

Japanese Patent Laying-Open No. 2015-205982 JP 2010-033093 A US Patent Application Publication No. 2012/0021141

However, when the PSA technique is applied to the horizontal alignment mode such as the IPS mode or the FFS mode, the contrast of the liquid crystal display device may be lowered. This is because conventional biphenyl-based or terphenyl-based monomers have no molecular structure anisotropy, and the monomers are irradiated with non-polarized ultraviolet rays for polymerization. This is probably because the film is not oriented along the orientation direction of the orientation film under the polymer layer.

The present invention has been made in view of the above situation, and includes a liquid crystal composition and a liquid crystal display device capable of increasing contrast, and a method of manufacturing a liquid crystal display device capable of manufacturing such a liquid crystal display device. It is intended to provide.

One embodiment of the present invention is a liquid crystal composition that includes a liquid crystal material and at least one monomer, and the at least one monomer includes a monomer having a photofunctional group having anisotropy in light absorption. Good.

Another embodiment of the present invention includes a liquid crystal material and at least one monomer, and the at least one monomer may have a cinnamate group which may have a substituent, or a substituent. A liquid crystal composition comprising at least one photoreactive monomer selected from the group consisting of a monomer having a good chalcone group and a monomer having an azobenzene group which may have a substituent. Good.

Still another embodiment of the present invention includes a liquid crystal layer containing a liquid crystal material, a sealing material disposed so as to surround the liquid crystal layer in a plan view, a pair of substrates that sandwich the liquid crystal layer, and a plan view. An alignment control layer disposed in contact with the liquid crystal layer in a region surrounded by the sealing material, wherein the alignment control layer allows the liquid crystal compound in the liquid crystal material to be perpendicular to the substrate surface or The liquid crystal display device is a liquid crystal display device comprising a polymer obtained by polymerizing at least one monomer, wherein the at least one monomer includes at least one monomer represented by the following chemical formula (1). May be.

(In formula, P < ¹ > and P < ² > are the same or different, and represent a vinyl group or an isopropenyl group.
Sp ¹ , Sp ² and Sp ³ are the same or different and are —O— group, —S— group, —COO— group, —OCO— group, —NHCO— group, —CONH— group, —NHCS— group, —CSNH— represents a direct bond.
Z ¹ and Z ² are the same or different and each represents a linear, branched or cyclic alkylene group having 1 to 12 carbon atoms or a direct bond.
At least one hydrogen atom of the phenylene group may be substituted. )

Still another embodiment of the present invention includes a step of sealing a liquid crystal composition containing a liquid crystal material and at least one monomer between a pair of substrates bonded by a sealing material to form a liquid crystal layer, and the liquid crystal Irradiating the layer with polarized ultraviolet light, and forming an alignment control layer obtained by polymerizing the at least one monomer between the pair of substrates and the liquid crystal layer, wherein the at least one monomer is A liquid crystal display device comprising a monomer having a photofunctional group having anisotropy in light absorption, wherein the alignment control layer aligns a liquid crystal compound in the liquid crystal material in a vertical or horizontal direction with respect to the substrate surface. It may be a manufacturing method.

Patent Document 1 discloses a liquid crystal composition that contains an alignment control material that is highly compatible with other liquid crystal compositions and has excellent alignment control power, and polymerizes a polymerizable compound contained in the liquid crystal composition. By doing so, it is disclosed to form an orientation control layer. Patent Document 2 discloses that a polyfunctional monomer having a symmetric structure mixed in a liquid crystal is polymerized and the liquid crystal is vertically aligned by the obtained ultraviolet cured product. Patent Document 3 discloses a liquid crystal alignment composition containing a photoreactive norbornene polymer, a binder, a reactive mesogen, and a photoinitiator.

However, none of the above Patent Documents 1 to 3 disclose a specific monomer having a photofunctional group having anisotropy in light absorption such as a cinnamate group, and it is considered to irradiate the monomer with polarized ultraviolet rays. It has not been. Further, in Patent Document 2, the polyfunctional monomer is polymerized by irradiating non-polarized ultraviolet light, but the method for producing a liquid crystal display device of the present invention is different in that the monomer is irradiated with polarized ultraviolet light. Patent Document 3 described above forms the alignment film by applying the liquid crystal alignment composition on a substrate, but the present invention is different in that a monomer for forming an alignment control layer is added to the liquid crystal layer (liquid crystal material). .

According to the liquid crystal composition, the liquid crystal display device, and the manufacturing method of the liquid crystal display device of the present invention, the contrast of the liquid crystal display device can be increased.

1 is a schematic cross-sectional view of a liquid crystal display device according to Embodiment 1. FIG. 1 is a schematic plan view of a liquid crystal display device according to Embodiment 1. FIG. 6 is a schematic cross-sectional view of a liquid crystal display device according to a modification of Embodiment 1. FIG. In the manufacturing method of the liquid crystal display device of Embodiment 1, it is the schematic diagram explaining the formation process of the orientation control layer, (a) represents before polymerization of a monomer, (b) represents after polymerization of a monomer. 6 is a schematic cross-sectional view of a liquid crystal display device according to Embodiment 2. FIG. In the manufacturing method of the liquid crystal display device of Embodiment 2, it is the schematic diagram explaining the formation process of the orientation control layer, (a) represents before polymerization of a monomer, (b) represents after polymerization of a monomer.

Hereinafter, embodiments of the present invention will be described. The present invention is not limited to the contents described in the following embodiments, and appropriate design changes can be made within a range that satisfies the configuration of the present invention.

In the present specification, the “photoreactive monomer” means a monomer containing a photofunctional group.

In the present specification, the “photofunctional group” means a functional group capable of causing a photoreaction.

In this specification, “observation surface side” means a side closer to the screen (display surface) of the liquid crystal display device, and “back side” means the screen (display surface) of the liquid crystal display device. Means the farther side.

In the present specification, the “retardation layer” means a retardation layer that gives an in-plane retardation of at least 10 nm to light having a wavelength of 550 nm. Incidentally, light having a wavelength of 550 nm is light having the highest human visibility. The in-plane phase difference is defined by R = (ns−nf) × d. Here, ns represents the larger one of the main refractive indexes nx and ny in the in-plane direction of the retardation layer, and nf is the smaller one of the main refractive indexes nx and ny in the in-plane direction of the retardation layer. Represents. The main refractive index indicates a value with respect to light having a wavelength of 550 nm unless otherwise specified. The in-plane slow axis of the retardation layer indicates an axis in a direction corresponding to ns, and the in-plane fast axis indicates an axis in a direction corresponding to nf. d represents the thickness of the retardation layer. In this specification, unless otherwise specified, “phase difference” or “retardation” means an in-plane phase difference with respect to light having a wavelength of 550 nm.

In this specification, a space between a pair of substrates included in a pair of substrates sandwiching a liquid crystal layer is referred to as “in-cell”, and the outside of the pair of substrates (observation surface side and back surface side) is referred to as “out-cell”.

<Embodiment 1>
<Liquid crystal display device>
First, the liquid crystal display device of Embodiment 1 will be described with reference to FIGS. FIG. 1 is a schematic cross-sectional view of the liquid crystal display device according to the first embodiment. FIG. 2 is a schematic plan view of the liquid crystal display device according to the first embodiment. As shown in FIGS. 1 and 2, the liquid crystal display device 100 of the present embodiment includes a liquid crystal layer 30 containing a liquid crystal material, a sealing material 40 disposed so as to surround the liquid crystal layer 30 in plan view, and a seal A pair of

substrates

10 and 20 that are bonded to each other by the material 40 and sandwich the liquid crystal layer 30; and an alignment control layer 50 that is disposed so as to be in contact with the liquid crystal layer 30 in a region surrounded by the sealing material 40 in plan view. Is provided. The liquid crystal display device 100 further includes a backlight 70 behind one of the pair of

substrates

10 and 20.

In recent years, liquid crystal display devices tend to widen the display area, and there is a demand for narrowing the frame area. The display area is an area for displaying an image recognized by an observer, and does not include a frame area. A gate driver, a source driver, a display control circuit, and the like are accommodated in the frame area. As one of the methods for narrowing the frame region, it has been studied to reduce the area of the sealing material for bonding a pair of substrates, but when the width of the sealing material is reduced, the peel strength between the substrates is reduced, One substrate may peel from the other substrate. More specifically, the liquid crystal display device usually forms an alignment film on the surface of each substrate, and then bonds both substrates with a sealing material to form a liquid crystal layer. Therefore, the alignment film is formed between the sealing material and the substrate. Is intervening. And since the adhesive strength between the sealing material and the alignment film is low, peeling is likely to occur at the interface between the alignment film and the sealing material, and as a result, peeling of the substrate may occur. The reason why the adhesion strength between the sealing material and the alignment film is low is that the surface of the alignment film is generally hydrophobic, while the resin contained in the sealing material is slightly hydrophilic, and these have low affinity. is there.

On the other hand, the liquid crystal display device 100 of the present embodiment does not have to have a conventional alignment film on the surface of the pair of

substrates

10 and 20 on the liquid crystal layer 30 side. 20 are joined together. A pair of substrates can be used even when the width of the sealing material 40 is reduced by narrowing the frame by making the

substrates

10 and 20 and the sealing material 40 contact each other without using a conventional alignment film to increase the peel strength. The adhesion of 10 and 20 can be maintained. In this case, the alignment film does not have to be formed at a position overlapping with the sealing material 40 at least in a plan view. However, the alignment film is formed only at a position overlapping with the sealing material 40 for accuracy of a printing apparatus used for forming the alignment film. Since it is difficult not to form, it is preferable that the alignment film is not formed on the entire surface of the pair of

substrates

10 and 20. In the present invention, the “alignment film” refers to a single layer film or a laminate composed of polyimide, polyamic acid, polyamide, polymaleimide, polysiloxane, polysilsesquioxane, polyphosphazene, or a copolymer thereof. A film or a film in which silicon oxide is formed by oblique vapor deposition and can control the orientation of a liquid crystal material. In a general liquid crystal display device, an alignment film material is directly applied (for example, application of polyimide or the like) or vapor deposition (for example, oblique deposition of silicon oxide (SiO)) on a substrate surface constituting a display region. Thereby, an alignment film is formed. The alignment film is not limited to those subjected to alignment treatment as long as an existing alignment film material such as polyimide is applied or an existing alignment film material such as silicon oxide is obliquely deposited. .

FIG. 3 is a schematic cross-sectional view of a liquid crystal display device according to a modification of the first embodiment. As shown in FIG. 3, in this embodiment, from the viewpoint of long-term reliability, an alignment film 80 is provided between the alignment control layer 50 and at least one of the pair of

substrates

10 and 20. Also good. The alignment film 80 may align the liquid crystal compound in a desired direction, for example, align the liquid crystal compound uniformly in a predetermined direction, or may not align the liquid crystal compound in the desired direction, for example, The liquid crystal compound may be aligned randomly without being aligned uniformly. However, from the viewpoint of reliably increasing the peel strength between the

substrates

10 and 20, there is an alignment film between the alignment control layer 50 and at least one of the substrates 10 and 20 (more preferably, the substrates 10 and 20). Preferably it is not provided.

As the alignment film 80, an alignment film usually used in the field of liquid crystal display devices can be used. For example, polyimide, polyamic acid, polyamide, polymaleimide, polysiloxane, polysilsesquioxane, polyphosphazene, or And a single layer film or a laminated film composed of at least one of these copolymers, or a film in which silicon oxide is formed by oblique deposition. The alignment film 80 may not be subjected to alignment treatment, but is preferably subjected to alignment treatment. The alignment treatment method is not particularly limited, and a rubbing method, a photo-alignment method, or the like can be used, but a photo-alignment method is preferable. This is because the alignment treatment of the alignment film 80 and the polymerization of the monomer described later can be performed at the same time, and the manufacturing process can be simplified.

When the alignment film 80 has been subjected to photo-alignment treatment, the alignment film 80 preferably contains a polymer having a photofunctional group. The photofunctional group of the alignment film 80 is irradiated with light (electromagnetic waves) such as ultraviolet light and visible light, for example, dimerization (dimer formation), isomerization, light fleece transition, decomposition, etc. The functional group is preferably a functional group capable of causing a change and exhibiting orientation regulating power. Specific examples of the photofunctional group of the alignment film 80 include an azobenzene group, a chalcone group, a cinnamate group, a coumarin group, a tolan group, and a stilbene group.

Examples of the pair of

substrates

10 and 20 include a combination of an active matrix substrate (TFT substrate) and a color filter (CF) substrate.

As the active matrix substrate, those normally used in the field of liquid crystal display devices can be used. When the active matrix substrate is viewed in plan, the transparent matrix 21 has a plurality of parallel gate signal lines; a plurality of parallel gate signal lines extending in a direction perpendicular to the gate signal lines and parallel to each other. Source signal lines; active elements such as thin film transistors (TFTs) arranged corresponding to the intersections of the gate signal lines and the source signal lines; arranged in a matrix in a region partitioned by the gate signal lines and the source signal lines A configuration in which the pixel electrode 24 and the like are provided can be given. In the case of the horizontal electric field display mode, a common wiring; a common electrode 22 connected to the common wiring, and the like are further provided. The pixel electrode 24 and the common electrode 22 may be stacked via the insulating layer 23. As the TFT, an amorphous silicon, polysilicon, or an oxide semiconductor IGZO (indium-gallium-zinc-oxygen) is preferably used.

In the active matrix display method, normally, when the TFT provided in each pixel is on, a signal voltage is applied to the electrode through the TFT, and the charge charged in the pixel at this time is applied during the period when the TFT is off. Hold on. A voltage holding ratio (VHR) indicates a ratio of holding the charged charge during one frame period (for example, 16.7 ms). That is, a low VHR means that the voltage applied to the liquid crystal layer tends to decay with time. In the active matrix display method, it is required to increase the VHR.

As the color filter substrate, those usually used in the field of liquid crystal display devices can be used. Examples of the configuration of the color filter substrate include a configuration in which a black matrix 12 formed in a lattice shape, a color filter 13 formed inside a lattice, that is, a pixel, and the like are provided on a transparent substrate 11. The color filter 13 may include a red color filter 13R, a green color filter 13G, and a blue color filter 13B. The thickness of the blue color filter 13B may be thicker than the thickness of the red color filter 13R and the thickness of the green color filter 13G. By increasing the thickness of the blue color filter 13B, the thickness of the liquid crystal layer can be reduced and the cell thickness can be optimized. On the surface of the color filter 13, an overcoat layer 14 (dielectric constant ε = 3 to 4) for flattening the uneven surface may be disposed. When the color filter substrate has the overcoat layer 14, the overcoat layer 14 and the sealing material 40 are in contact with each other, but the peel strength of the sealing material does not decrease.

The pair of

substrates

10 and 20 may be one in which both the color filter and the active matrix are formed on one substrate.

As shown in FIG. 2, the sealing material 40 is disposed so as to surround the liquid crystal layer 30 in a plan view. The sealing material 40 may be cured by light such as ultraviolet rays, may be cured by heat, or may be cured by both light and heat. Examples of the sealing material 40 include those containing an epoxy resin, a (meth) acrylic resin, and the like. The sealing material 40 may contain an inorganic filler, an organic filler, a curing agent, or the like. As the sealing material 40, for example, Sekisui Chemical Co., Ltd., Photorec, etc. can be used.

The width of the sealing material 40 in plan view may be 0.4 mm or more and 5 mm or less. A more preferable lower limit of the width of the sealing material 40 is 0.6 mm, a more preferable upper limit is 4 mm, and a further preferable upper limit is 2 mm. The width of the sealing material 40 may be 1.0 mm or less. In the liquid crystal display device 100 of the present embodiment, the

substrates

10 and 20 and the sealing material 40 can be in direct contact with each other. Even if it is below, the board | substrate 10 and the board | substrate 20 can fully be joined.

The liquid crystal layer 30 contains a liquid crystal material including at least one liquid crystal compound (liquid crystal molecule) 31. The liquid crystal material is a thermotropic liquid crystal, and is preferably a liquid crystal material exhibiting a nematic phase (nematic liquid crystal). The liquid crystal material preferably has a phase transition to an isotropic phase when the temperature rises from a nematic phase and reaches a certain critical temperature (nematic phase-isotropic phase transition point (T _NI )) or higher. The liquid crystal layer 30 preferably exhibits a nematic phase under the usage environment of the liquid crystal display device (for example, −40 ° C. to 90 ° C.). The temperature of the nematic phase-isotropic phase transition point of the liquid crystal material is not particularly limited, but is, for example, 70 to 110 ° C. The above T _NI is a T _NI of liquid crystal material before the monomer to be described later is added.

The liquid crystal material and the liquid crystal compound 31 may have negative values or negative values of dielectric anisotropy (Δε) defined by the following formula. That is, the liquid crystal material and the liquid crystal compound 31 may have a negative dielectric anisotropy or may have a positive dielectric anisotropy. Those having a dielectric anisotropy of 1 are preferred, and those having a positive dielectric anisotropy are preferred from the viewpoint of light resistance. In addition, the liquid crystal material having a positive dielectric anisotropy and the liquid crystal compound 31 have characteristics such as high T _NI and high-speed response (low rotational viscosity). As the liquid crystal material having negative dielectric anisotropy, for example, a material having Δε of −1 to −20 can be used. As the liquid crystal material having positive dielectric anisotropy, for example, a material having Δε of 1 to 20 can be used. Furthermore, the liquid crystal layer 30 and the liquid crystal material may contain a liquid crystal compound (neutral liquid crystal compound) having no polarity, that is, Δε is substantially zero. Examples of the neutral liquid crystal compound include a liquid crystal compound having an alkene structure. Hereinafter, a liquid crystal material and a liquid crystal compound having a negative dielectric anisotropy are also referred to as a negative liquid crystal material and a negative liquid crystal compound, respectively, and a liquid crystal material and a liquid crystal compound having a positive dielectric anisotropy are respectively a positive liquid crystal material. Also called a positive liquid crystal compound.
Δε = (dielectric constant in the major axis direction)-(dielectric constant in the minor axis direction)

The liquid crystal material may contain a liquid crystal compound having an alkenyl group. The liquid crystal compound having an alkenyl group is preferably a neutral liquid crystal compound. By including the liquid crystal compound having an alkenyl group, the rotational viscosity of the liquid crystal material is improved, so that the response performance of the liquid crystal material can be improved and the speed can be increased. On the other hand, a liquid crystal compound having an alkenyl group has low light resistance and may be decomposed by irradiation with ultraviolet rays or the like to cause a decrease in VHR. Therefore, in the vertical alignment type alignment film-less mode that irradiates non-polarized light and the conventional PSA technique, when a liquid crystal compound having an alkenyl group that has a problem in light resistance is used, a significant decrease in VHR is caused. On the other hand, in this embodiment, the orientation control layer 50 contains a polymer obtained by polymerizing a specific monomer, and the monomer has a photofunctional group having anisotropy in light absorption, and is uniaxial. Since it is polymerized by polarized light that is light only in the direction and expresses the alignment regulating force, the light irradiation intensity applied to the liquid crystal layer 30 can be greatly reduced as compared with non-polarized light. Even if the liquid crystal material includes a positive liquid crystal compound, the positive liquid crystal compound exhibits high light resistance as described above. Therefore, even if a liquid crystal compound having an alkenyl group is introduced into the liquid crystal material, reliability problems such as a reduction in VHR are unlikely to occur.

The liquid crystal compound having an alkenyl group may be a compound represented by any of the following chemical formulas (4-1) to (4-4). Any of these may be used alone or in combination of two or more.

(Wherein, m and n are the same or different and are integers of 1 to 6)

Specific examples of the liquid crystal compound having an alkenyl group include a compound represented by the following chemical formula (4-1-1).

As shown in FIG. 2, the orientation control layer 50 is disposed in a region surrounded by the sealing material 40 in a plan view. The alignment control layer 50 is disposed in contact with the liquid crystal layer 30, and aligns the liquid crystal compound 31 in the liquid crystal material included in the liquid crystal layer 30 in the horizontal direction with respect to the surfaces of the

substrates

10 and 20. In the alignment control layer 50, the alignment control layer 50 controls the alignment of the liquid crystal material in a state where a voltage higher than the threshold value of the liquid crystal material is not applied to the liquid crystal layer 30. In addition, aligning the liquid crystal compound 31 in the liquid crystal material in the horizontal direction with respect to the

substrates

10 and 20 means that the pretilt angle of the liquid crystal material with respect to the

substrates

10 and 20 is 10 ° or less. The pretilt angle is more preferably 3 ° or less. The pretilt angle refers to an angle formed by the major axis of the liquid crystal material (liquid crystal compound 31) with respect to the surface of the substrate when the applied voltage to the liquid crystal layer 30 is less than the threshold voltage (including no voltage applied). The surface is 0 ° and the substrate normal is 90 °.

The alignment control layer 50 contains a polymer obtained by polymerizing at least one monomer added to the liquid crystal layer 30, and the at least one monomer is an optical functional group having anisotropy in light absorption (hereinafter, polarized light). A monomer having an absorption functional group) (hereinafter also referred to as a polarization-absorbing monomer). Therefore, the orientation control layer 50 is a polymer layer containing a polymer including at least a unit derived from a polarization-absorbing monomer. The at least one monomer may be a monofunctional monomer having one polymerizable group, but the polymerizable group is preferably a plurality of polyfunctional monomers, and in particular, a bifunctional monomer having two polymerizable groups. Is preferred.

The contrast of the liquid crystal display device 100 can be improved by forming the alignment control layer 50 containing a polymer containing a unit derived from the polarization-absorbing monomer. The reason is considered as follows. Since the polarization-absorbing functional group has anisotropy in light (preferably ultraviolet light) absorption, it exhibits orientation upon irradiation with polarized light (preferably polarized ultraviolet light, more preferably linearly polarized ultraviolet light). More specifically, the polarized light-absorbing functional group oriented in a specific direction corresponding to the direction of the polarization axis undergoes a photoreaction upon irradiation with polarized light. As a result, the polarization-absorbing monomer is polymerized to form a polymer along a specific orientation direction. Therefore, since the liquid crystal compound 31 is aligned in a desired alignment direction by the alignment control layer 50 derived from the polarization-absorbing monomer without forming the alignment film 80, the contrast of the liquid crystal display device 100 can be improved. Even when the alignment film 80 is formed, the polarization-absorbing monomer is polymerized along the alignment direction of the alignment film 80 by appropriately setting the polarization axis direction of the polarized light to be irradiated, so that a polymer is formed. The Therefore, also in this case, the contrast of the liquid crystal display device 100 can be improved.

As described above, the polarization-absorbing monomer has a polarization-absorbing functional group, and the polarization-absorbing functional group absorbs polarized light (preferably polarized ultraviolet rays, more preferably linearly polarized ultraviolet rays) and exhibits an alignment regulating force. it can. Since the irradiation with polarized light irradiates only light in the uniaxial direction, the light irradiation intensity with which the liquid crystal layer 30 is irradiated can be made lower than the irradiation with non-polarized light. The alignment control layer 50 can align the liquid crystal compound 31 in the liquid crystal material in the horizontal direction with respect to the substrate surface by the polarization absorbing monomer exhibiting the alignment regulating force. The polarization-absorbing monomer has at least one (preferably two or more, more preferably two) polymerizable groups and is polymerized by irradiation with light such as ultraviolet rays to form a polymer. The polymer separates the phase of the liquid crystal layer 30 to form the alignment control layer 50.

Whether or not the light absorption of the photofunctional group of the monomer has anisotropy can be verified by measuring the polarization absorption spectrum. Specifically, first, a polarizer is set on both sides of an object to be measured (for example, a film or a solution). Then, the light absorption spectrum is measured by setting the polarizers in a crossed Nicol arrangement and a parallel Nicol arrangement, respectively, and the presence or absence of anisotropy is confirmed by comparing the absorbance at the same wavelength based on the measured light absorption spectrum. If there is a difference in absorbance between the crossed Nicol arrangement and the parallel Nicol arrangement, the photofunctional group to be measured has anisotropy in the absorption of light of that wavelength.

Although the specific example of the said polarization absorption functional group is not specifically limited, From the viewpoint of aligning the liquid crystal compound 31 in the horizontal direction with respect to the

substrates

10 and 20 and controlling the orientation direction of the liquid crystal compound 31, the above-mentioned polarization absorption functional group. The group is at least one photofunctional group selected from the group consisting of a cinnamate group that may have a substituent, a chalcone group that may have a substituent, and an azobenzene group that may have a substituent. (Hereinafter also referred to as a functional group for horizontal alignment). That is, the at least one monomer includes a monomer having a cinnamate group which may have a substituent, a monomer having a chalcone group which may have a substituent, and an azobenzene group which may have a substituent. It is preferable to include at least one photoreactive monomer selected from the group consisting of monomers having the above, and the polarized light absorbing monomer is preferably the photoreactive monomer.

Although the kind of said substituent is not specifically limited, A halogen group, a methyl group, a methoxy group, an ethyl group, and an ethoxy group can be mentioned as a suitable example. Any of these may be used alone or in combination of two or more. That is, the substituent preferably includes at least one substituent selected from the group consisting of a halogen group, a methyl group, a methoxy group, an ethyl group, and an ethoxy group. The at least one monomer may include a photoreactive monomer having a functional group for horizontal alignment having a substituent and a photoreactive monomer having a functional group for horizontal alignment having no substituent. As the halogen group, a fluoro group and a chloro group are preferred. When the horizontal alignment functional group has a substituent, the substituent is usually substituted with at least one hydrogen atom of a ring structure such as a phenylene group of the horizontal alignment functional group. The functional group for horizontal alignment may be a monovalent functional group, but is preferably a divalent cinnamate group represented by the following chemical formula (3-1), represented by the following chemical formula (3-2). And a divalent azobenzene group represented by the following chemical formula (3-3).

The polarized light absorbing functional group preferably contains a cinnamate group, and the at least one photoreactive monomer more preferably contains at least one monomer having a cinnamate group which may have the substituent. The cinnamate group absorbs ultraviolet light having the shortest wavelength among the three functional groups for horizontal alignment (specifically, ultraviolet light having a wavelength range of 290 to 330 nm), and the backlight 70 when the liquid crystal display device 100 is used. This is because the possibility of absorbing the irradiation light is extremely small and the light resistance is most excellent.

Examples of the photoreaction of the polarized light-absorbing functional group generated by polarized light irradiation include dimerization reaction (dimer formation), isomerization reaction, photofleece transfer reaction, decomposition reaction, etc. Irradiation with (preferably linearly polarized ultraviolet rays) causes a dimerization reaction (dimer formation) and an isomerization reaction.

From the viewpoint of the solubility in the liquid crystal material and the orientation controllability of the liquid crystal compound by polarized light absorption, a polarized light absorbing monomer having a cinnamate group (a monomer having a cinnamate group which may have the above substituent) is: It is preferable to include at least one monomer represented by chemical formula (1) (hereinafter also referred to as monomer (1)).

(Wherein P ¹ and P ² are the same or different and each represents a vinyl (ethenyl) group or an isopropenyl (1-methylethenyl) group.
Sp ¹ , Sp ² and Sp ³ are the same or different and are —O— group, —S— group, —COO— group, —OCO— group, —NHCO— group, —CONH— group, —NHCS— group, —CSNH— represents a direct bond.
Z ¹ and Z ² are the same or different and each represents a linear, branched or cyclic alkylene group having 1 to 12 carbon atoms or a direct bond.
At least one hydrogen atom of the phenylene group may be substituted. )

In the chemical formula (1), at least one hydrogen atom of the phenylene group is the same or different and is substituted with a halogen atom (preferably a fluorine atom or a chlorine atom), a methyl group, a methoxy group, an ethyl group, or an ethoxy group. May be.

More specific examples of the monomer (1) include compounds represented by any one of the following chemical formulas (1-1) to (1-4). Any of these may be used alone or in combination of two or more.

(In the formula, p and q are the same or different and are 0 or 1, and m and n are the same or different and are integers of 0 to 12.)

More specific examples of the monomer (1) include compounds represented by any of the following chemical formulas (2-1) to (2-12). Any of these may be used alone or in combination of two or more.

(In the formula, p is 0 or 1 (preferably 0), and m is 2, 4, 6, 8, 10 or 12.)

(Wherein n is 2, 4, 6, 8, 10 or 12)

Wherein p is 0 or 1 (preferably 0), n is 2, 4, 6, 8, 10 or 12, and m is 2, 4, 6, 8, 10 or 12. is there.)

In particular, the monomer (1) preferably contains at least one of the monomer represented by the chemical formula (2-1) and the monomer represented by the chemical formula (2-2). This is because the monomers represented by the chemical formulas (2-1) and (2-2) do not have a spacer between the polymerizable group and the cinnamate group, and can improve the liquid crystal alignment.

A polarizing plate (linear polarizer) 60 may be disposed on the opposite side of the pair of

substrates

10 and 20 from the liquid crystal layer 30. The polarizing plate 60 typically includes a polyvinyl alcohol (PVA) film obtained by adsorbing and orienting an anisotropic material such as an iodine complex having dichroism. Usually, a protective film such as a triacetyl cellulose film is laminated on both sides of the PVA film and put to practical use. An optical film such as a retardation film may be disposed between the polarizing plate 60 and the pair of

substrates

10 and 20.

The transmission axes of the pair of polarizing plates 60 are preferably orthogonal to each other. According to such a configuration, since the pair of polarizing plates 60 are arranged in crossed Nicols, a good black display state can be realized when no voltage is applied.

In the present specification, that two axes (directions) are orthogonal means that an angle (absolute value) between the two axes (direction) is within a range of 90 ± 3 ° unless otherwise specified, preferably 90 ±. It is within the range of 1 °, more preferably within the range of 90 ± 0.5 °, and particularly preferably 90 ° (fully orthogonal).

As shown in FIGS. 1 and 3, in the liquid crystal display device of the present embodiment, a backlight 70 is disposed on the back side of the liquid crystal panel. A liquid crystal display device having such a configuration is generally called a transmissive liquid crystal display device. The backlight 70 is not particularly limited as long as it emits light including visible light, may emit light including only visible light, and emits light including both visible light and ultraviolet light. It may be.

The liquid crystal display device of the present embodiment includes an external circuit such as a TCP (tape carrier package) and a PCB (printed wiring board) in addition to the liquid crystal panel and the backlight 70; an optical film such as a viewing angle widening film and a brightness enhancement film. A plurality of members such as a bezel (frame), and some members may be incorporated in other members. Members other than those already described are not particularly limited, and those normally used in the field of liquid crystal display devices can be used, and thus description thereof is omitted.

The liquid crystal display device 100 may be in a horizontal electric field type display mode. Examples of the horizontal electric field type display mode include an IPS mode, an FFS mode, and an electric field control birefringence (ECB) mode.

In the FFS mode, for example, at least one of the

substrates

10 and 20 is provided with a structure (FFS electrode structure) including a planar electrode, a slit electrode, and an insulating film disposed between the planar electrode and the slit electrode. An oblique electric field (fringe electric field) is formed in the liquid crystal layer 30. Normally, the slit electrode, the insulating film, and the planar electrode are arranged in this order from the liquid crystal layer 30 side. As the slit electrode, for example, a slit having a linear opening surrounded by the electrode around the entire circumference, or a linear notch provided with a plurality of comb teeth and disposed between the comb teeth. The comb-shaped thing which comprises a slit can be used.

In the IPS mode, for example, a pair of comb electrodes is provided on at least one of the

substrates

10 and 20, and a lateral electric field is formed in the liquid crystal layer 30. As the pair of comb-shaped electrodes, for example, an electrode pair that includes a plurality of comb-tooth portions and is arranged so that the comb-tooth portions mesh with each other can be used.

In the ECB mode, for example, a pixel electrode is provided on one of the

substrates

10 and 20, a counter electrode is provided on the other substrate, and a liquid crystal material having a positive dielectric anisotropy is used. The retardation of the liquid crystal material is changed by the voltage applied between the pixel electrode and the counter electrode to control the transmission and non-transmission of light.

In the present embodiment, the case where the liquid crystal drive mode of the liquid crystal display device 100 is the horizontal alignment mode is described in detail. However, the liquid crystal drive mode according to the present embodiment is not particularly limited and is a vertical alignment mode. Alternatively, the alignment control layer 50 may align the liquid crystal compound 31 in the liquid crystal material in a direction substantially perpendicular to the surfaces of the

substrates

10 and 20.

<Liquid crystal composition and method for producing liquid crystal display device>
Next, the liquid crystal composition of this embodiment and the method for manufacturing the liquid crystal display device will be described. The liquid crystal display device manufacturing method of the present embodiment includes a step of sealing a liquid crystal composition containing a liquid crystal material and at least one monomer between a pair of substrates joined by a sealing material to form a liquid crystal layer; Illuminating the liquid crystal layer with polarized ultraviolet light, and forming an alignment control layer formed by polymerizing the at least one monomer between the pair of substrates and the liquid crystal layer, and the at least one monomer. Includes a monomer (polarization-absorbing monomer) having a photofunctional group (polarization-absorbing functional group) having anisotropy in light absorption, and the alignment control layer includes a liquid crystal compound in the liquid crystal material with respect to the substrate surface. In other words, it may be a method of manufacturing a liquid crystal display device that is aligned in the horizontal direction. The liquid crystal composition of this embodiment contains a liquid crystal material and at least one monomer, and the at least one monomer has a photofunctional group (polarized light absorption functional group) having anisotropy in light absorption ( A liquid crystal composition containing a polarization absorbing monomer) may be used. The liquid crystal composition of this embodiment also contains a liquid crystal material and at least one monomer, and the at least one monomer has a cinnamate group that may have a substituent and a substituent. It may be a liquid crystal composition containing at least one photoreactive monomer selected from the group consisting of a monomer having a good chalcone group and a monomer having an azobenzene group which may have a substituent.

Hereinafter, although each process and a liquid crystal composition are further demonstrated, since each member and a monomer are as having mentioned above, description is abbreviate | omitted.

The manufacturing method of the liquid crystal display device of the present embodiment includes a step of forming a liquid crystal layer by sealing a liquid crystal composition containing a liquid crystal material and at least one monomer between a pair of substrates bonded by a sealing material. . From the viewpoint of reliably increasing the peel strength between a pair of substrates, the method for manufacturing a liquid crystal display device of the present embodiment requires at least one of the pair of substrates (more preferably a pair of substrates) before the step of forming the liquid crystal layer. It is preferable not to have a step of forming an alignment film on the surface of both of the substrates). In this case, the pair of substrates are joined so as to be in direct contact with the sealing material without the alignment film interposed therebetween. On the other hand, the manufacturing method of the liquid crystal display device of the present embodiment includes a step of forming an alignment film on at least one surface of the pair of substrates before the step of forming the liquid crystal layer from the viewpoint of long-term reliability. In this case, an alignment film is interposed between at least one of the pair of substrates and the sealing material, and the pair of substrates is bonded via the alignment film. The alignment film is formed, for example, by applying an alignment film material containing polyamic acid or the like on at least one surface of a pair of substrates, and volatilizing the solvent in the alignment film material by heating, followed by baking. be able to. Thereafter, the alignment film may or may not be subjected to an alignment treatment before the step of forming the liquid crystal layer. Examples of the alignment treatment include photo-alignment treatment such as rubbing treatment and ultraviolet irradiation. When performing the photo-alignment treatment, in the step of forming the alignment control layer, the polymerization of the monomer and the photo-alignment treatment of the alignment film may be simultaneously performed by ultraviolet irradiation. Thereby, the manufacturing process can be simplified.

In the step of forming the liquid crystal layer, the liquid crystal composition may be sealed as long as the liquid crystal composition is sandwiched between the pair of substrates by the sealing material, and the sealing material may not be cured. Curing of the sealing material may be performed separately from the step of forming the orientation control layer described later, or may be performed simultaneously. As described above, the sealing material may be cured by light such as ultraviolet rays, may be cured by heat, or may be cured by both light and heat. .

The liquid crystal layer can be formed by, for example, filling a liquid crystal composition between a pair of substrates by a vacuum injection method or a drop injection method. When the vacuum injection method is adopted, a liquid crystal layer is formed by applying a sealing material, bonding a pair of substrates, curing the sealing material, injecting a liquid crystal composition, and sealing the injection port in this order. To do. When the dropping injection method is employed, a liquid crystal layer is formed by applying a sealing material, dropping a liquid crystal composition, bonding a pair of substrates, and curing the sealing material in this order.

As described above, the liquid crystal material may have a negative dielectric anisotropy or a positive dielectric anisotropy. The liquid crystal material may contain a liquid crystal compound having an alkenyl group. The liquid crystal material may contain one or more liquid crystal compounds.

The at least one monomer includes a monomer having a photofunctional group (polarized light absorbing functional group) having anisotropy in light absorption (polarized light absorbing monomer). The polarization-absorbing monomer has a polarization-absorbing functional group and can absorb polarized light (preferably polarized ultraviolet rays, more preferably linearly-polarized ultraviolet rays) to exhibit an alignment regulating force. Since the irradiation with polarized light irradiates only light in the uniaxial direction, the light irradiation intensity with which the liquid crystal layer is irradiated can be made lower than the irradiation with non-polarized light.

The polarization-absorbing monomer content in the liquid crystal composition is preferably 0.03% by weight or more and 5% by weight or less, more preferably 0.05% by weight or more and 4.5% by weight or less, More preferably, it is 0.1 weight% or more and 3 weight% or less. If the concentration of the polarization-absorbing monomer is too low, horizontal alignment control of the liquid crystal compound by the alignment control layer may not be sufficient, and if the concentration of the polarization-absorbing monomer is too high, long-term reliability due to the remaining polarization-absorbing monomer There is a possibility of deterioration.

As described above, the at least one monomer may have a monomer having a cinnamate group which may have a substituent, a monomer having a chalcone group which may have a substituent, and a substituent. It is preferable to include at least one photoreactive monomer selected from the group consisting of monomers having an azobenzene group, and the polarized light absorbing monomer is preferably the photoreactive monomer.

In the method of manufacturing a liquid crystal display device according to this embodiment, the liquid crystal layer is irradiated with polarized ultraviolet light, and an alignment control layer is formed by polymerizing the at least one monomer between the pair of substrates and the liquid crystal layer. The process of carrying out. The polarized ultraviolet light is preferably linearly polarized ultraviolet light. The alignment control layer is formed at the interface between the pair of substrates and the liquid crystal layer when the alignment film is not formed, and when the alignment film is formed, the interface between the substrate or the alignment film and the liquid crystal layer. Formed. When the alignment film is formed on both substrates, the alignment control layer is formed at the interface between each alignment film and the liquid crystal layer. When the alignment film is formed only on one substrate, the alignment control layer is It is formed at the interface between the liquid crystal layer and the interface between the substrate on which the alignment film is not formed and the liquid crystal layer. As described above, when the photo-alignment process of the alignment film is performed in accordance with the polymerization of the monomer, the alignment film is subjected to the alignment process by this step.

The wavelength of the polarized ultraviolet light may be 200 nm or more and 430 nm or less. A more preferable lower limit of the wavelength is 250 nm, and a more preferable upper limit is 380 nm. Dose of the polarized ultraviolet is, 0.3 J / cm ² or more, may be 20 J / cm ² or less. A more preferable lower limit of the irradiation amount is 1 J / cm ² , and a more preferable upper limit is 5 J / cm ² .

In the step of forming the alignment control layer, the liquid crystal layer may be irradiated with polarized ultraviolet rays while being heated at a temperature not lower than the nematic phase-isotropic phase transition point of the liquid crystal material and not higher than 140 ° C. 4A and 4B are schematic diagrams illustrating the formation process of the alignment control layer in the method for manufacturing the liquid crystal display device of Embodiment 1, wherein FIG. 4A shows before polymerization of the monomer, and FIG. 4B shows after polymerization of the monomer. To express. In FIG. 4A, the arrow indicates polarized ultraviolet light. As shown in FIG. 4A, polarized ultraviolet rays are irradiated while heating a liquid crystal layer 30 containing a liquid crystal material containing a liquid crystal compound 31 and at least one monomer. Thereby, at least one monomer is polymerized to produce a polymer. As the polymer undergoes phase separation from the liquid crystal layer, an alignment control layer 50 is formed between the pair of substrates and the liquid crystal layer, as shown in FIG.

By heating the liquid crystal layer 30 at a temperature _{equal to} or higher than the nematic phase-isotropic phase transition point (T _NI ) of the liquid crystal material, the state of the irradiated polarized ultraviolet rays can be prevented from being changed by the liquid crystal material in the liquid crystal layer. Therefore, a liquid crystal display device having a higher degree of orientation (high contrast) can be manufactured. The heating temperature is preferably 3 ° C. or more higher than the nematic phase-isotropic phase transition point of the liquid crystal material. The upper limit of the heating temperature is, for example, 140 ° C. from the viewpoint of suppressing deterioration of the liquid crystal material due to heat as much as possible. Conditions such as heating time and heating means are not particularly limited. The method for measuring the nematic phase-isotropic phase transition point of the liquid crystal material is, for example, by differential scanning calorimetry (DSC) or by directly observing the temperature dependence by enclosing the liquid crystal material in a capillary. can do.

By having the step of forming the alignment control layer after the step of forming the liquid crystal layer, the pair of substrates sandwiching the liquid crystal layer are joined to each other by the sealant and surrounded by the sealant in plan view. An orientation control layer can be formed in the region. Further, as the alignment control layer forming monomer, a polarization-absorbing monomer (preferably the photoreactive monomer) is polymerized to form an alignment control layer that aligns the liquid crystal material in the horizontal direction with respect to the substrate surface. Can do.

After the above steps, the liquid crystal display device of this embodiment is completed through an attaching step of a polarizing plate and attaching a control unit, a power supply unit, a backlight, and the like.

When the liquid crystal display device is in a normally black mode, for example, on the outside of the pair of substrates, a pair of polarizing plates are arranged in crossed Nicols so that the absorption axes are orthogonal to each other, and the absorption axes of the pair of polarizing plates; It arrange | positions so that the angle which the irradiation axis of polarized ultraviolet rays makes may be 0 degree or 90 degrees. In a state where a voltage equal to or higher than the threshold is not applied to the liquid crystal layer, the light from the backlight does not pass through the liquid crystal layer and is displayed in black. When a voltage higher than the threshold is applied to the liquid crystal layer, the angle formed between the absorption axis of the pair of polarizing plates arranged in the crossed Nicols and the irradiation axis becomes, for example, 45 °, and light from the backlight transmits through the liquid crystal layer. And white display. The irradiation axis is the vibration direction of polarized ultraviolet light. By changing the direction of irradiation of polarized ultraviolet light onto the substrate, the alignment division treatment can be performed.

The liquid crystal display device 100 is preferably in the horizontal electric field type display mode. Examples of the horizontal electric field type display mode include an IPS mode, an FFS mode, and an electric field control birefringence (ECB) mode.

<Embodiment 2>
In the present embodiment, features unique to the present embodiment will be mainly described, and the description overlapping with the first embodiment will be omitted. Moreover, in this embodiment and Embodiment 1, the same code | symbol is attached | subjected to the member which has the same or the same function, and description of the member is abbreviate | omitted in this embodiment. As will be described below, the present embodiment is substantially the same as the first embodiment except that an in-cell retardation layer and an out-cell retardation layer are provided.

The liquid crystal display device may be used under strong external light such as outdoors. For this reason, in recent years, there has been a demand for a liquid crystal display device excellent in outdoor visibility in which reflection of external light is suppressed. As a method for suppressing reflection of external light in a liquid crystal display device, it is conceivable to provide a circularly polarizing plate made of a combination of a retardation layer and a linearly polarizing plate. In particular, in the horizontal alignment mode, two retardation layers are used in order to simultaneously realize the external light antireflection function and the liquid crystal display. In that case, the two retardation layers are provided inside and outside the liquid crystal cell. The retardation layer inside the liquid crystal cell, that is, the in-cell retardation layer, is generally formed by polymerizing a reactive mesogen (RM) on the alignment layer. Here, since the alignment layer is present only in one of the in-cell retardation layers (RM), the orientation of the in-cell retardation layer is low. When the orientation of the in-cell retardation layer is low, the thermal stability is lowered, and when the firing step is performed to form the alignment film on the in-cell retardation layer, the retardation of the in-cell retardation layer is lowered. According to this embodiment, it is possible to solve such a problem.

<Liquid crystal display device>
The liquid crystal display device of Embodiment 2 will be described with reference to FIG. FIG. 5 is a schematic cross-sectional view of the liquid crystal display device according to the second embodiment. The liquid crystal display device 100B of Embodiment 2 further includes an out-cell retardation layer 61 disposed between the substrate 10 and the polarizing plate 60, and an in-cell retardation layer 90 disposed between the substrate 10 and the orientation control layer 50. Have.

As the out-cell retardation layer 61, a stretched polymer film generally used in the field of liquid crystal display devices can be used. Examples of the material of the polymer film include cycloolefin polymer, polycarbonate, polysulfone, polyethersulfone, polyethylene terephthalate, polyethylene, polyvinyl alcohol, norbornene, triacetyl cellulose, diacetyl cellulose, and the like. Among them, cycloolefin polymer Is preferred. A retardation layer formed of a cycloolefin polymer is excellent in durability and has an advantage that a change in retardation is small when exposed to a high temperature environment or a high temperature and high humidity environment for a long period of time. As a film of a cycloolefin polymer, “ZEONOR FILM (registered trademark)” manufactured by Nippon Zeon Co., Ltd., “ARTON (registered trademark) film” manufactured by JSR Corporation, and the like are known.

The in-cell retardation layer 90 is formed by laminating an alignment layer 91 and a polymer 92 of a liquid crystalline monomer. The alignment layer 91 is for controlling the alignment of the liquid crystalline monomer constituting the polymer 92 to be laminated. By laminating and polymerizing a liquid crystalline monomer on the alignment layer 91, the liquid crystalline monomer can be fixed in a predetermined alignment direction, and a retardation layer having a desired retardation can be formed. On the other hand, the in-cell retardation layer 90 in which the alignment layer 91 and the polymer 92 of the liquid crystalline monomer are laminated has low heat resistance, and retardation due to heating tends to occur. Therefore, when the in-cell retardation layer 90 is formed by laminating the alignment layer 91 and the polymer 92 of the liquid crystalline monomer, the in-cell retardation layer 90 is not formed on the in-cell retardation layer 90. A decrease in retardation of 90 can be effectively suppressed.

As the alignment layer 91, for example, polyimide, polyamic acid, polyamide, polymaleimide, polysiloxane, polysilsesquioxane, polyphosphazene, or a monolayer film or a laminated film made of a copolymer thereof, or And a film in which silicon oxide is formed by oblique vapor deposition. The alignment layer 91 is preferably subjected to an alignment treatment. The alignment treatment method is not particularly limited, and a rubbing method, a photo alignment method, or the like can be used.

In the case where the alignment layer 91 is subjected to a photo-alignment treatment, the alignment layer 91 preferably contains a polymer having a photofunctional group. The photofunctional group of the alignment layer 91 is irradiated with light (electromagnetic waves) such as ultraviolet light and visible light, for example, dimerization (dimer formation), isomerization, light fleece transition, decomposition, etc. The functional group is preferably a functional group capable of causing a change and exhibiting orientation regulating power. Specific examples of the photofunctional group of the alignment layer 91 include an azobenzene group, a chalcone group, a cinnamate group, a coumarin group, a tolan group, and a stilbene group.

The liquid crystalline monomer is a polymerizable monomer having a refractive index anisotropy (reactive mesogen). The liquid crystalline monomer may be a monomer itself having a phase difference, and is a monomer capable of exhibiting a phase difference when the liquid crystalline monomer is polymerized on the alignment layer 91 subjected to the alignment treatment. May be. By polymerizing the liquid crystalline monomer, a decrease in retardation due to thermal fluctuation can be suppressed, and stability such as temperature stability can be improved. The phase difference of the in-cell retardation layer 90 is determined by the product of the birefringence Δn of the polymer 92 of the liquid crystalline monomer and the thickness d of the in-cell retardation layer 90.

The liquid crystalline monomer may include at least one of an acrylic monomer and a methacrylic monomer. The acrylic monomer has an acrylic group as a polymerization group. The methacrylic monomer has a methacryl group as a polymerization group. When the liquid crystalline monomer is an acrylic monomer, it is advantageous in that the reaction rate is fast. When the liquid crystalline monomer is a methacrylic monomer, the glass transition point is high, so that the temperature dependence of the retardation can be reduced.

Examples of the liquid crystalline monomer include compounds represented by the following chemical formulas (5-1) to (5-15). Any of these may be used alone or in combination of two or more.

(In formula, X < ¹ > and X < ² > are the same or different and represent a hydrogen atom or a methyl group.
g, h and i are the same or different and are an integer of 1 to 18.
j and k are the same or different and are integers of 1 to 12. )

The out-cell retardation layer 61 is preferably a retardation layer (λ / 4 plate) that gives an in-plane retardation of ¼ wavelength to light having a wavelength of at least 550 nm, and specifically, at least a wavelength of 550 nm. It is preferable that an in-plane retardation of 100 nm or more and 176 nm or less is imparted to the light. Since the out-cell retardation layer 61 functions as a λ / 4 plate, the combination of the polarizing plate 60 on the observation surface side and the out-cell retardation layer 61 can be functioned as a circularly polarizing plate. Thereby, since internal reflection of a liquid crystal panel can be reduced, the favorable black display by which reflection (reflection) of external light was suppressed is realizable.

In addition, the circularly polarized FFS mode liquid crystal in which only the out-cell phase difference layer 61 is incorporated in the FFS mode liquid crystal cannot perform black display. Therefore, the performance of the circularly polarized FFS mode liquid crystal is improved by further providing the in-cell phase difference layer 90. be able to. The in-plane retardation axis of the out-cell retardation layer 61 and the in-phase retardation layer 90 are orthogonal to each other, and the retardation value of the out-cell retardation layer 61 and the retardation value of the in-cell retardation layer 90 are Preferably equal. As a result, the out-cell retardation layer 61 and the in-cell retardation layer 90 can cancel the phase difference with respect to light incident from the normal direction of the liquid crystal panel. A state that does not exist is realized. That is, a configuration that is optically equivalent to a conventional lateral electric field mode liquid crystal panel with respect to light incident on the liquid crystal panel from the backlight 70 is realized. Therefore, it is possible to realize display in a transverse electric field mode using a circularly polarizing plate. Therefore, the in-cell retardation layer 90 is also preferably a retardation layer (λ / 4 plate) that imparts an in-plane retardation of ¼ wavelength to light having a wavelength of 550 nm, specifically, It is preferable to provide an in-plane retardation of 100 nm or more and 176 nm or less with respect to light having a wavelength of 550 nm.

In the following description, the orientation of the transmission axis of the polarizing plate 60 on the back side is defined as 0 °. At this time, the orientation of the transmission axis of the polarizing plate 60 on the observation surface side is preferably 90 °.

The in-plane slow axis of the out-cell retardation layer 61 and the in-plane slow axis of the in-cell retardation layer 90 are 45 ° with respect to each transmission axis of the pair of polarizing plates 60 from the viewpoint of expressing the function of the retardation layer. It is preferable to make the angle. That is, it is preferable that one of the in-plane slow axis of the out-cell retardation layer 61 and the in-plane slow axis of the in-cell retardation layer 90 has an azimuth of 45 ° and the other has an azimuth of 135 °.

In the present specification, “the two axes (directions) form an angle of 45 °” means that the angle (absolute value) formed by both axes is within a range of 45 ± 3 ° unless otherwise specified. , Preferably within a range of 45 ± 1 °, more preferably within a range of 45 ± 0.5 °, and particularly preferably 45 ° (completely 45 °).

The preferred arrangement of the optical axis in the present embodiment is, for example, when the orientation of the transmission axis of the polarizing plate 60 on the back side is 0 °, the in-plane slow axis of the in-cell retardation layer 90 is 45 °, and the liquid crystal layer 30 The initial alignment direction of the liquid crystal material is 0 ° or 90 °, the in-plane slow axis of the out-cell retardation layer 61 is −45 °, and the transmission axis of the polarizing plate 60 on the observation surface side is 90 °.

In addition, the liquid crystal display device 100B of Embodiment 2 may include other constituent members. For example, by providing an antireflection film on the observation surface side of the polarizing plate 60 on the observation surface side, the reflectance of the liquid crystal panel is provided. Can be further reduced. As the antireflection film, a moth-eye film having a ridge-like surface structure is preferably used.

In this embodiment, the in-cell retardation layer 90 is disposed between the out-cell retardation layer 61 and the liquid crystal layer 30, and the case where the in-cell retardation layer 90 is applied to a transverse electric field mode using a circularly polarizing plate is described in detail. The use of the in-cell retardation layer according to the present embodiment is not particularly limited, and may be used for a liquid crystal display device other than the transverse electric field mode using a circularly polarizing plate. For example, an in-cell retardation layer in which the presence or absence of a retardation function is patterned may be provided in the anti-transmissive liquid crystal display device so that a phase difference is given to the reflecting part and no phase difference is given to the transmissive part. The patterning of the retardation function can be realized, for example, by performing an alignment process on the alignment layer 91 in the reflective portion and not performing an alignment process on the alignment layer 91 in the transmission portion using a mask. Further, the arrangement of the in-cell retardation layer according to the present embodiment is not particularly limited as long as it is between the base materials of the pair of substrates, and may be provided on both the

substrates

10 and 20, for example, depending on the application. However, it may be provided only on the substrate 120.

Further, in the present embodiment, the case where the liquid crystal drive mode of the liquid crystal display device of the present embodiment is the horizontal alignment mode is described in detail. However, the liquid crystal drive mode according to the present embodiment is not particularly limited, and is vertical. The alignment mode may be used, and the alignment control layer 50 may align the liquid crystal compound 31 in the liquid crystal material in a direction substantially perpendicular to the surfaces of the

substrates

10 and 20.

<Liquid crystal composition and method for producing liquid crystal display device>
The manufacturing method of the liquid crystal display device of Embodiment 2 is the liquid crystal of Embodiment 1 except having the process of forming an in-cell retardation layer in at least one of a pair of board | substrates before the process of forming the said liquid crystal layer. This is the same as the manufacturing method of the display device. As for the liquid crystal composition, the same liquid crystal composition as that of the first embodiment can be used in this embodiment.

In the step of forming the in-cell retardation layer, when the in-cell retardation layer is formed on a color filter substrate, for example, after forming a black matrix, a color filter, an overcoat layer, etc., the in-cell retardation layer is formed. Form. When the in-cell retardation layer is formed on the active matrix substrate, for example, the in-cell retardation layer is formed after forming a common electrode, a pixel electrode, a TFT, various signal lines, and the like.

In the step of forming the in-cell retardation layer, an alignment layer is formed on the surface of at least one substrate, a composition containing a liquid crystalline monomer is applied to the alignment layer, and the liquid crystalline monomer is polymerized. Good. The alignment layer includes, for example, an alignment layer composition containing polyimide, polyamic acid, polyamide, polymaleimide, polysiloxane, polysilsesquioxane, or polyphosphazene on at least one surface of a pair of substrates. It is formed by applying or obliquely depositing an alignment layer composition containing silicon oxide and performing firing or the like. The alignment layer composition may contain a polymer having the photofunctional group described above.

The alignment layer is preferably subjected to an alignment treatment. The alignment treatment method is not particularly limited, and a rubbing method, a photo alignment method, or the like can be used.

Polymerization of the liquid crystalline monomer is performed, for example, by irradiation with light such as visible light or ultraviolet light. Polymerization of the liquid crystalline monomer is performed in a bulk polymerization without using a solvent (bulk polymerization) or in a state where the liquid crystalline monomer is at a high concentration, so the degree of polymerization of the liquid crystalline monomer is low, for example, a weight average molecular weight of 30,000 or less It is thought that. Therefore, when an in-cell retardation layer is formed by laminating a liquid crystalline monomer polymer on the alignment layer, the heat resistance of the in-cell retardation layer is particularly low. For example, when heating at 200 ° C. or higher, retardation is liable to decrease. .

The liquid crystalline monomer may include at least one of an acrylic monomer and a methacrylic monomer.

After the step of forming the in-cell retardation layer, a step of forming a liquid crystal layer and a step of forming an alignment control layer are performed as in the first embodiment.

6A and 6B are schematic diagrams illustrating the formation process of the alignment control layer in the method of manufacturing the liquid crystal display device of Embodiment 2, wherein FIG. 6A shows the state before the polymerization of the monomer, and FIG. 6B shows the state after the polymerization of the monomer. To express. As shown in FIG. 6A, also in this embodiment, polarized ultraviolet rays are irradiated while heating the liquid crystal layer 30 containing a liquid crystal material containing a liquid crystal compound and at least one monomer. However, from the viewpoint of suppressing the change in the phase difference of the in-cell retardation layer 90 due to the irradiation of the polarized ultraviolet light, the polarized ultraviolet light is irradiated from the substrate (for example, the substrate 20) side on which the in-cell retardation layer 90 is not formed. Is preferred. By irradiation with polarized ultraviolet rays, at least one monomer is polymerized to produce a polymer. As the polymer undergoes phase separation from the liquid crystal layer, as shown in FIG. 6B, an alignment control layer 50 is formed between the pair of substrates and the liquid crystal layer.

Thus, in this embodiment, it is not necessary to form an alignment film on the in-cell retardation layer 90, and a high-temperature (for example, 200 ° C. or higher) firing step for forming the alignment film is unnecessary. It can suppress effectively that the phase difference of the in-cell phase difference layer 90 falls resulting from a process. Also in this embodiment, to heat the liquid crystal panel including a liquid crystal layer 30 upon irradiation of the polarized ultraviolet light, the temperature, because T _NI more liquid crystal material, a relatively low temperature and 140 ° C. or less, cell retardation The influence on the phase difference of the layer 90 is small.

5 and 6 show the case where the alignment film 80 is disposed on a substrate (for example, the substrate 20) on which the in-cell retardation layer 90 is not formed. In this embodiment, the alignment film 80 is It does not have to be formed.

As mentioned above, although embodiment of this invention was described, each described matter can be applied with respect to this invention altogether.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples.

<Example 1>
(Preparation of liquid crystal composition)
A liquid crystal compound having a negative dielectric anisotropy (negative liquid crystal compound) and a liquid crystal compound having an alkenyl group and having a dielectric anisotropy of substantially 0 (neutral liquid crystal compound); A negative absorptive monomer having a negative anisotropy (Δε = −3.0) and a liquid crystal phase-isotropic phase transition point (T _NI ) of 80 ° C. is combined with a polarization-absorbing monomer and the photoreactive monomer ( After adding 0.3% by weight of a monomer represented by the following chemical formula (2-1) as a monomer for forming an orientation control layer), the monomer is completely contained in the liquid crystal material by leaving it at 25 ° C. for 24 hours. The liquid crystal composition was prepared by dissolving.

(Production of liquid crystal panel)
An FFS mode liquid crystal panel was actually produced by the following method. First, a pixel electrode having an FFS electrode structure made of indium tin oxide (ITO), an ITO substrate on which an insulating film and a common electrode were stacked, and a counter substrate having no electrode were prepared. A horizontal photo-alignment type alignment film material (horizontal photo-alignment agent) was applied to both substrates, and then baked at 200 ° C. for 40 minutes to form a horizontal photo-alignment film. Subsequently, a sealing material (manufactured by Sekisui Chemical Co., Ltd., Photorec) is applied to one substrate, the liquid crystal composition obtained above is dropped onto the region surrounded by the sealing material, and the other substrate is bonded. A liquid crystal panel was produced.

Subsequently, at 25 ° C., using a black light (FHF32BLB-T manufactured by Toshiba Lighting & Technology Co., Ltd.), linearly polarized ultraviolet light (wavelength: 300 to 340 nm) from the normal direction is applied to the liquid crystal panel without applying voltage. Irradiation was performed at 7 mW / cm ² for 1200 seconds ( ² J / cm ² ) to form an alignment control layer, align the horizontal photo alignment film, and cure the sealing material. Thereafter, the liquid crystal panel was heated to 120 ° C. and then rapidly cooled to realign the liquid crystal compound, and an FFS mode liquid crystal panel having an alignment film and an alignment control layer (polymer layer) was produced.

<Comparative Example 1>
An FFS mode liquid crystal panel of Comparative Example 1 was produced in the same manner as Example 1 except for the following points. In this comparative example, a monomer represented by the following chemical formula (A) was added to the negative liquid crystal material instead of the monomer represented by the chemical formula (2-1). Further, in this comparative example, it was necessary to irradiate the linearly polarized ultraviolet ray at 1.7 mW / cm ² for 4120 seconds (7 J / cm ² ) until the monomer in the liquid crystal layer disappeared completely.

<Characteristic evaluation 1>
The following characteristic evaluation was performed on the FFS mode liquid crystal panels manufactured in Example 1 and Comparative Example 1.

(Contrast measurement)
The measurement was performed in a dark room at 25 ° C. using a spectroradiometer SR-1 manufactured by Topcon Technohouse.

(VHR measurement)
VHR was measured under conditions of 1 V and 70 ° C. using a 6254 type VHR measuring system manufactured by Toyo Technica.

(Residual DC (rDC) measurement)
Residual DC after applying a DC offset voltage of 3 V to the liquid crystal panel for 2 hours in an environment of 25 ° C. was measured by a flicker elimination method. The results are shown in Table 1 below.

From the results shown in Table 1, Example 1 using a monomer having a cinnamate group had higher contrast and VHR and smaller rDC than Comparative Example 1 using a monomer having a biphenyl group. The main factor of the high contrast in Example 1 is that the monomer has a cinnamate group which is a polarization-absorbing functional group and polymerizes while being aligned by irradiation with linearly polarized ultraviolet rays, and a polymer is formed along a predetermined direction. Therefore, it is considered that the liquid crystal compound takes a highly aligned state. Further, it is considered that the orientation of the horizontal photo-alignment film also has a positive influence on the orientation of the polymer. On the other hand, the main factor of the low contrast of Comparative Example 1 is that the monomer has a biphenyl group that is not a polarization-absorbing functional group, and polymerizes without being oriented by itself even when irradiated with linearly polarized ultraviolet light, and is polymerized along a predetermined direction. This is probably because the alignment state of the liquid crystal compound was lowered. However, also in Comparative Example 1, the polymer may be slightly oriented due to the influence of the horizontal light alignment film. The reason why the VHR is higher in Example 1 is that the monomer represented by the chemical formula (2-1) is used in the case of using the monomer represented by the chemical formula (A) than in the case where the monomer represented by the chemical formula (A) is used. This is thought to be because the consumption speed was high, and as a result, the amount of UV irradiation was reduced. In addition, with regard to rDC, the factor that was able to be smaller when the monomer represented by the chemical formula (2-1) was used than when the monomer represented by the chemical formula (A) was used. It is presumed that the amount of impurities, particularly ionic impurities, was small, and that the polymer layer having a cinnamate group was less likely to adsorb ionic impurities than the polymer layer having a biphenyl group.

<Example 2-1>
(Preparation of liquid crystal composition)
A liquid crystal compound having a negative dielectric anisotropy (negative liquid crystal compound) and a liquid crystal compound having an alkenyl group and having a dielectric anisotropy of substantially 0 (neutral liquid crystal compound); A negative absorptive monomer having a negative anisotropy (Δε = −2.8) and a liquid crystal phase-isotropic phase transition point (T _NI ) of 75 ° C. is combined with a polarization-absorbing monomer and the photoreactive monomer ( After adding 1.0% by weight of a monomer represented by the following chemical formula (2-2) as a monomer for forming an alignment control layer), the monomer is completely contained in the liquid crystal material by leaving it to stand at 25 ° C. for 24 hours. The liquid crystal composition was prepared by dissolving.

(Production of liquid crystal panel)
An FFS mode liquid crystal panel was actually produced by the following method. First, a pixel electrode having an FFS electrode structure made of indium tin oxide, an ITO substrate on which an insulating film and a common electrode were laminated, and a counter substrate having no electrode were prepared. Subsequently, a sealing material (manufactured by Sekisui Chemical Co., Ltd., Photorec) is applied to one substrate, the liquid crystal composition obtained above is dropped onto the region surrounded by the sealing material, and the other substrate is bonded. A liquid crystal panel was produced.

Subsequently, while heating the temperature of the liquid crystal panel to T _NI or higher (100 ° C.), using an ultra-high pressure mercury lamp (manufactured by USHIO INC.), Linear polarization from the normal direction to the liquid crystal panel without applying voltage. Ultraviolet rays (wavelength 300 to 340 nm) were irradiated at 1.7 mW / cm ² for 600 seconds (1 J / cm ² ) to form the orientation control layer and cure the sealing material. The width of the sealing material after curing was 0.5 mm. Thereafter, the temperature of the liquid crystal panel was returned to room temperature, thereby producing an FFS mode liquid crystal panel having no alignment film and having an alignment control layer (polymer layer).

<Example 2-2>
Example 2-2 was performed in the same manner as Example 2-1 except that in the step of forming the orientation control layer, linearly polarized ultraviolet light was irradiated at 1.7 mW / cm ² for 1800 seconds (3 J / cm ² ). A liquid crystal panel was prepared.

<Example 2-3>
Example 2-3 was carried out in the same manner as Example 2-1 except that in the step of forming the orientation control layer, linearly polarized ultraviolet light was irradiated at 1.7 mW / cm ² for 3000 seconds (5 J / cm ² ). A liquid crystal panel was prepared.

<Comparative example 2>
A liquid crystal panel of Comparative Example 2 was prepared in the same manner as in Example 2-1, except that the alignment control layer was not irradiated with linearly polarized ultraviolet light (0 J / cm ² ).

<Characteristic evaluation 2>
The FFS mode liquid crystal panels produced in Examples 2-1 to 2-3 and Comparative Example 2 were evaluated for the above characteristics in the same manner as in Example 1 and Comparative Example 1. The results are shown in Table 2 below.

From the results shown in Table 2, the contrast improved with an increase in the amount of polarized ultraviolet light irradiation. This is because when the cinnamate monomer represented by the chemical formula (2-2) is used, the formed cinnamate polymer layer is liquid crystal because the cinnamate group exhibits polarization absorptivity simultaneously with polymerization by irradiation with polarized ultraviolet rays. It shows that the orientation direction of the compound is controlled. VHR showed a substantially constant value in the range of polarized UV irradiation dose of 0 to 5 J / cm ² , but VHR slightly decreased with increasing dose from 3 J / cm ² to 5 J / cm ² . Therefore, when the irradiation amount is 3 J / cm ² or more, there is a possibility that VHR is lowered due to deterioration of liquid crystal molecules due to the increase in irradiation amount. The rDC decreased with increasing polarized UV irradiation dose. Thereby, it is considered that the adsorption of ionic impurities in the liquid crystal layer is less likely to occur because the polymer layer is formed by polymerization of the cinnamate monomer.

<Example 3-1>
(Preparation of liquid crystal composition)
A liquid crystal compound having a positive dielectric anisotropy (positive liquid crystal compound) and a liquid crystal compound having an alkenyl group and having a dielectric anisotropy of substantially 0 (neutral liquid crystal compound); A positive-type liquid crystal material having a positive rate anisotropy (Δε = 7.0) and a liquid crystal phase-isotropic phase transition point (T _NI ) of 85 ° C., a polarization-absorbing monomer and the photoreactive monomer (alignment) After adding 1.0% by weight of the monomer represented by the chemical formula (2-2) as the control layer forming monomer), the monomer is completely dissolved in the liquid crystal material by leaving it to stand at 25 ° C. for 24 hours. To prepare a liquid crystal composition.

<Example 3-2>
Example 3-2 was performed in the same manner as in Example 3-1, except that in the step of forming the orientation control layer, linearly polarized ultraviolet light was irradiated at 1.7 mW / cm ² for 1800 seconds (3 J / cm ² ). A liquid crystal panel was prepared.

<Example 3-3>
Example 3-3 is the same as Example 3-1 except that in the step of forming the orientation control layer, linearly polarized ultraviolet light was irradiated at 1.7 mW / cm ² for 3000 seconds (5 J / cm ² ). A liquid crystal panel was prepared.

<Comparative Example 3>
A liquid crystal panel of Comparative Example 3 was produced in the same manner as in Example 3-1, except that the alignment control layer was not irradiated with linearly polarized ultraviolet rays (0 J / cm ² ).

<Characteristic evaluation 3>
For the FFS mode liquid crystal panels produced in Examples 3-1 to 3-3 and Comparative Example 3, the characteristics were evaluated in the same manner as in Example 1 and Comparative Example 1. The results are shown in Table 3 below.

From the results shown in Table 3, the contrast was improved with an increase in the irradiation amount of polarized ultraviolet rays even when a liquid crystal material having positive dielectric anisotropy was used. This is because when the cinnamate monomer represented by the chemical formula (2-2) is used, the formed cinnamate polymer layer is liquid crystal because the cinnamate group exhibits polarization absorptivity simultaneously with polymerization by irradiation with polarized ultraviolet rays. It shows that the orientation direction of the compound is controlled. However, it was a lower value in the total polarized ultraviolet irradiation amount than in the case of using a liquid crystal material having negative dielectric anisotropy. This is because a liquid crystal material having a positive dielectric anisotropy moves slightly in the direction in which the liquid crystal compound rises with respect to the substrate when a voltage is applied, so that the transmittance is lower than a liquid crystal material having a negative dielectric anisotropy. This is because it is low. VHR shows a substantially constant value in the range of polarized UV irradiation dose of 0 to 5 J / cm ² , and is higher than when a liquid crystal material having negative dielectric anisotropy is used. It is estimated that a liquid crystal material having a positive dielectric anisotropy is less likely to be deteriorated by ultraviolet irradiation. The rDC became significantly smaller as the amount of polarized ultraviolet rays increased. Thereby, it is considered that the adsorption of ionic impurities in the liquid crystal layer is less likely to occur because the polymer layer is formed by polymerization of the cinnamate monomer. In addition, the value was an order of magnitude smaller than when a liquid crystal material having negative dielectric anisotropy was used. This is presumably because the liquid crystal material having positive dielectric anisotropy is less likely to be deteriorated by ultraviolet irradiation, as in the VHR result.

<Example 4-1>
(Preparation of liquid crystal composition)
A liquid crystal compound having a positive dielectric anisotropy (positive liquid crystal compound) and a liquid crystal compound having an alkenyl group and having a dielectric anisotropy of substantially 0 (neutral liquid crystal compound); A positive-type liquid crystal material having a positive rate anisotropy (Δε = 7.0) and a liquid crystal phase-isotropic phase transition point (T _NI ) of 85 ° C., a polarization-absorbing monomer and the photoreactive monomer (alignment) A monomer (m = 2) represented by the following chemical formula (2-3-1) is added as a control layer-forming monomer (1.0% by weight), and then allowed to stand in a 25 ° C. environment for 24 hours. A monomer was completely dissolved therein to prepare a liquid crystal composition.

Subsequently, while heating the temperature of the liquid crystal panel to T _NI or higher (100 ° C.), using an ultra-high pressure mercury lamp (manufactured by USHIO INC.), Linear polarization from the normal direction to the liquid crystal panel without applying voltage. Ultraviolet rays (wavelength 300 to 340 nm) were irradiated at 1.7 mW / cm ² for 3000 seconds (5 J / cm ² ) to form the orientation control layer and cure the sealing material. The width of the sealing material after curing was 0.5 mm. Thereafter, the temperature of the liquid crystal panel was returned to room temperature, thereby producing an FFS mode liquid crystal panel having no alignment film and having an alignment control layer (polymer layer).

<Example 4-2>
The monomer (m = 4) represented by the chemical formula (2-3-1) was added to the positive liquid crystal material instead of the monomer (m = 2) represented by the chemical formula (2-3-1). A liquid crystal panel of Example 4-2 was produced in the same manner as Example 4-1, except for the above.

<Example 4-3>
A monomer (m = 6) represented by the chemical formula (2-3-1) was added to the positive liquid crystal material instead of the monomer (m = 2) represented by the chemical formula (2-3-1). A liquid crystal panel of Example 4-3 was produced in the same manner as Example 4-1, except for the above.

<Example 4-4>
A monomer (m = 8) represented by the chemical formula (2-3-1) was added to the positive liquid crystal material instead of the monomer (m = 2) represented by the chemical formula (2-3-1). A liquid crystal panel of Example 4-4 was produced in the same manner as Example 4-1, except for the above.

<Example 4-5>
Instead of the monomer (m = 2) represented by the chemical formula (2-3-1), the monomer (m = 10) represented by the chemical formula (2-3-1) was added to the positive liquid crystal material. A liquid crystal panel of Example 4-5 was produced in the same manner as Example 4-1, except for the above.

<Example 4-6>
A monomer (m = 12) represented by the chemical formula (2-3-1) was added to the positive liquid crystal material instead of the monomer (m = 2) represented by the chemical formula (2-3-1). A liquid crystal panel of Example 4-6 was produced in the same manner as Example 4-1, except for the above.

<Characteristic evaluation 4>
For the FFS mode liquid crystal panels fabricated in Examples 4-1 to 4-6, the above-described characteristic evaluation was performed in the same manner as in Example 1 and Comparative Example 1. The results are shown in Table 4 below.

From the results shown in Table 4, VHR and rDC were good results at any value of m in the above chemical formula (2-3-1), indicating high VHR and low rDC. On the other hand, as the value of m increases, the contrast tends to increase slightly. As the alkyl chain length increases, the flexibility of the monomer is improved. Particularly, when m is 8 or more, the controllability of the orientation direction of the liquid crystal compound is considered to be slightly improved.

<Example 5>
(Production of liquid crystal panel)
An FFS mode liquid crystal panel was actually produced by the following method. First, a TFT substrate (active matrix substrate) in which a pixel electrode having an FFS electrode structure made of indium tin oxide (ITO) made of indium tin oxide (ITO), an insulating film, and a common electrode is laminated, and having no electrode. A counter substrate in which an alignment layer and an in-cell retardation layer were laminated in this order on a color filter was prepared. The in-cell retardation layer is made of a polymer obtained by polymerizing a reactive acrylic monomer on an alignment layer subjected to rubbing treatment. Subsequently, a horizontal alignment polyimide (polyamic acid) -based alignment film material (alignment agent) is applied to the TFT substrate, followed by baking in an oven at 200 ° C. for 40 minutes, and then a rubbing treatment to perform horizontal processing. An alignment film was formed. Subsequently, a sealing material (manufactured by Sekisui Chemical Co., Ltd., Photorec) is applied to the counter substrate, the same liquid crystal composition as in Example 1 is dropped on the area surrounded by the sealing material, and the TFT substrate is bonded to the liquid crystal panel. Was made.

Subsequently, while heating the temperature of the liquid crystal panel than _{T NI} (100 ° C.), a black light (Toshiba Lighting & Technology Corp., FHF32BLB-T) using, the TFT substrate side when no voltage is applied to the liquid crystal panel From the normal direction, linearly polarized ultraviolet light (wavelength 300 to 340 nm) was irradiated at 1.7 mW / cm ² for 3000 seconds (5 J / cm ² ) to form the orientation control layer and cure the sealing material. In addition, the ultraviolet irradiation and the rubbing treatment were performed so that the azimuth direction in which the liquid crystal molecules are aligned by the alignment control layer by linearly polarized ultraviolet irradiation is the same as the azimuth direction in which the liquid crystal molecules are aligned by the rubbing treatment of the alignment film. Thereafter, the temperature of the liquid crystal panel was returned to room temperature to produce an FFS mode liquid crystal panel having an alignment control layer (polymer layer) and an in-cell retardation layer.

When the visibility of the liquid crystal panel of this example was confirmed outdoors, it was good.

[Appendix]
One embodiment of the present invention (hereinafter also referred to as a first embodiment) contains a liquid crystal material and at least one monomer, and the at least one monomer has a photofunctional group having anisotropy in light absorption. The liquid crystal composition characterized by including the monomer which has may be sufficient. Since the liquid crystal composition includes a monomer (polarization-absorbing monomer) having a photofunctional group (polarization-absorbing functional group) having anisotropy in the light absorption, a liquid crystal display device produced using the liquid-crystal composition The contrast can be improved.

In the first aspect of the present invention, the photofunctional group having anisotropy in light absorption includes a cinnamate group which may have a substituent, a chalcone group which may have a substituent, and a substituent. It may contain at least one photofunctional group (functional group for horizontal alignment) selected from the group consisting of azobenzene groups that may have. Thereby, the horizontal alignment (control of alignment azimuth | direction) of a liquid crystal compound is attained.

Another embodiment of the present invention (hereinafter also referred to as a second embodiment) contains a liquid crystal material and at least one monomer, and the at least one monomer may have a substituent. And at least one photoreactive monomer selected from the group consisting of a monomer having a chalcone group which may have a substituent, and a monomer having an azobenzene group which may have a substituent. The liquid crystal composition characterized by the above may be used. Since the photofunctional group includes a photoreactive monomer that can function as a polarization-absorbing monomer, the contrast of a liquid crystal display device manufactured using the liquid crystal composition can be improved.

In the first aspect of the present invention, the photofunctional group having anisotropy in light absorption may include a cinnamate group which may have the substituent. In the second embodiment of the present invention, the at least one photoreactive monomer may include at least one monomer having a cinnamate group which may have the substituent. As a result, the light resistance of the liquid crystal display device can be improved.

In the first and second embodiments of the present invention, the monomer having a cinnamate group which may have a substituent may include at least one monomer (monomer (1)) represented by the following chemical formula (1). Good. Thereby, the solubility of the monomer in the liquid crystal material can be improved, and the alignment controllability of the liquid crystal compound by polarized light absorption can be further improved.

In the first and second embodiments of the present invention, the at least one monomer represented by the chemical formula (1) is represented by the monomer represented by the following chemical formula (2-1) and the following chemical formula (2-2). Or at least one of the monomers. Thereby, liquid crystal orientation can be made higher.

In the first and second aspects of the present invention, the liquid crystal material may have a positive dielectric anisotropy. Thereby, the light resistance of a liquid crystal display device can be improved.

In the first and second aspects of the present invention, the liquid crystal material may have negative dielectric anisotropy. Thereby, the contrast of the liquid crystal display device can be further improved.

In the first and second embodiments of the present invention, the liquid crystal material may contain a neutral liquid crystal compound having an alkenyl group. Thereby, the response performance of the liquid crystal material can be improved and the speed can be increased.

Still another embodiment of the present invention (hereinafter also referred to as a third embodiment) includes a liquid crystal layer containing a liquid crystal material, a sealing material disposed so as to surround the liquid crystal layer in plan view, and the liquid crystal layer. And an alignment control layer disposed in contact with the liquid crystal layer in a region surrounded by the sealing material in plan view, the alignment control layer in the liquid crystal material The liquid crystal compound is aligned vertically or horizontally with respect to the substrate surface, contains a polymer obtained by polymerizing at least one monomer, and the at least one monomer is represented by the following chemical formula (1). It may be a liquid crystal display device including at least one monomer (monomer (1)).

The monomer (1) has a cinnamate group that can function as a photofunctional group having anisotropy in light absorption (polarized light absorption functional group), and the orientation control layer includes at least one kind of the monomer (1). Since the polymer obtained by polymerizing the monomer is contained, the contrast of the liquid crystal display device can be improved. In the liquid crystal display device, a pair of substrates can be bonded to each other with a sealing material without using a conventional alignment film, so that the peel strength between the substrates can be increased. In addition, the monomer (1) has a cinnamate group that can function as a polarization-absorbing functional group, and can absorb polarized light and express an alignment regulating force. Therefore, the liquid crystal layer can be compared with irradiation with non-polarized light. It is possible to reduce the light irradiation intensity applied to the. Furthermore, since the liquid crystal display device does not have to include a conventional alignment film that requires a baking process, even if the in-cell retardation layer is provided, the retardation of the in-cell retardation layer is reduced by the baking process. This can be effectively suppressed. Moreover, since the monomer (1) has a cinnamate group, the light resistance of the liquid crystal display device can be improved. Furthermore, according to the monomer (1), the solubility of the monomer in the liquid crystal material can be improved, and the alignment controllability of the liquid crystal compound by polarized light absorption can be further improved.

In the third embodiment of the present invention, the at least one monomer represented by the chemical formula (1) includes a monomer represented by the following chemical formula (2-1) and a monomer represented by the following chemical formula (2-2): May be included. Thereby, liquid crystal orientation can be made higher.

In the third aspect of the present invention, the liquid crystal material may have a positive dielectric anisotropy. Thereby, the light resistance of the liquid crystal display device can be improved.

In the third aspect of the present invention, the liquid crystal material may have negative dielectric anisotropy. Thereby, the contrast of the liquid crystal display device can be further improved.

In the third aspect of the present invention, the liquid crystal material may contain a neutral liquid crystal compound having an alkenyl group. Thereby, the response performance of the liquid crystal material can be improved and the speed can be increased.

In the third aspect of the present invention, the liquid crystal display device may be in a horizontal electric field type display mode.

In still another embodiment of the present invention (hereinafter, also referred to as a fourth embodiment), a liquid crystal composition containing a liquid crystal material and at least one monomer is sealed between a pair of substrates bonded by a sealing material. Forming a liquid crystal layer, irradiating the liquid crystal layer with polarized ultraviolet light, and forming an alignment control layer obtained by polymerizing the at least one monomer between the pair of substrates and the liquid crystal layer; And the at least one monomer includes a monomer (polarization-absorbing functional group) having a photofunctional group (polarization-absorbing functional group) having anisotropy in light absorption, and the alignment control layer is formed in the liquid crystal material. The liquid crystal compound may be oriented vertically or horizontally with respect to the substrate surface.

In the fourth aspect of the present invention, in the step of forming the alignment control layer, polarized ultraviolet rays are irradiated while heating the liquid crystal layer at a temperature of not less than the nematic phase-isotropic phase transition point of the liquid crystal material and not more than 140 ° C. It may be irradiated.

Each aspect of the present invention described above may be appropriately combined without departing from the scope of the present invention.

10, 20: Substrate 11, 21: Transparent substrate 12: Black matrix 13: Color filter 14: Overcoat layer 22: Common electrode 23: Insulating layer 24: Pixel electrode 30: Liquid crystal layer 31: Liquid crystal compound (liquid crystal molecule)
40: Sealing material 50: Alignment control layer 60: Polarizing plate 61: Out-cell retardation layer 70: Backlight 80: Alignment film 90: In-cell retardation layer 91: Alignment layer 92: Liquid crystalline monomer polymer 100, 100B: Liquid crystal Display device

Claims

Containing a liquid crystal material and at least one monomer,
The at least one monomer is a monomer having a cinnamate group which may have a substituent, a monomer having a chalcone group which may have a substituent, and a monomer having an azobenzene group which may have a substituent. A liquid crystal composition comprising at least one photoreactive monomer selected from the group consisting of:
2. The liquid crystal composition according to claim 1, wherein the at least one photoreactive monomer contains at least one monomer having a cinnamate group which may have the substituent.
The liquid crystal composition according to claim 2, wherein the monomer having a cinnamate group which may have a substituent includes at least one monomer represented by the following chemical formula (1).

(In formula, P < 1 > and P < 2 > are the same or different, and represent a vinyl group or an isopropenyl group.
Sp 1 , Sp 2 and Sp 3 are the same or different and are —O— group, —S— group, —COO— group, —OCO— group, —NHCO— group, —CONH— group, —NHCS— group, —CSNH— represents a direct bond.
Z 1 and Z 2 are the same or different and each represents a linear, branched or cyclic alkylene group having 1 to 12 carbon atoms or a direct bond.
At least one hydrogen atom of the phenylene group may be substituted. )
The at least one monomer represented by the chemical formula (1) includes at least one of a monomer represented by the following chemical formula (2-1) and a monomer represented by the following chemical formula (2-2). The liquid crystal composition according to claim 3.
5. The liquid crystal composition according to claim 1, wherein the liquid crystal material has a positive dielectric anisotropy.
5. The liquid crystal composition according to claim 1, wherein the liquid crystal material has negative dielectric anisotropy.
The liquid crystal composition according to any one of claims 1 to 6, wherein the liquid crystal material contains a neutral liquid crystal compound having an alkenyl group.
A liquid crystal layer containing a liquid crystal material;
A sealing material disposed so as to surround the liquid crystal layer in plan view;
A pair of substrates sandwiching the liquid crystal layer;
In a region surrounded by the sealing material in plan view, an alignment control layer disposed so as to be in contact with the liquid crystal layer,
The alignment control layer is for aligning the liquid crystal compound in the liquid crystal material in the vertical or horizontal direction with respect to the substrate surface, and contains a polymer obtained by polymerizing at least one monomer,
The liquid crystal display device, wherein the at least one monomer includes at least one monomer represented by the following chemical formula (1).

(In formula, P < 1 > and P < 2 > are the same or different, and represent a vinyl group or an isopropenyl group.
Sp 1 , Sp 2 and Sp 3 are the same or different and are —O— group, —S— group, —COO— group, —OCO— group, —NHCO— group, —CONH— group, —NHCS— group, —CSNH— represents a direct bond.
Z 1 and Z 2 are the same or different and each represents a linear, branched or cyclic alkylene group having 1 to 12 carbon atoms or a direct bond.
At least one hydrogen atom of the phenylene group may be substituted. )
The at least one monomer represented by the chemical formula (1) includes at least one of a monomer represented by the following chemical formula (2-1) and a monomer represented by the following chemical formula (2-2). The liquid crystal display device according to claim 8.
The liquid crystal display device according to claim 8, wherein the liquid crystal material has a positive dielectric anisotropy.
10. The liquid crystal display device according to claim 8, wherein the liquid crystal material has negative dielectric anisotropy.
12. The liquid crystal display device according to claim 8, wherein the liquid crystal material contains a neutral liquid crystal compound having an alkenyl group.
13. The liquid crystal display device according to claim 8, wherein the liquid crystal display device is in a horizontal electric field type display mode.
A step of sealing a liquid crystal composition containing a liquid crystal material and at least one monomer between a pair of substrates bonded by a sealing material to form a liquid crystal layer;
Illuminating the liquid crystal layer with polarized ultraviolet light, and forming an alignment control layer formed by polymerizing the at least one monomer between the pair of substrates and the liquid crystal layer,
The at least one monomer includes a monomer having a photofunctional group having anisotropy in light absorption,
The method of manufacturing a liquid crystal display device, wherein the alignment control layer aligns a liquid crystal compound in the liquid crystal material in a vertical or horizontal direction with respect to the substrate surface.
The step of forming the alignment control layer irradiates polarized ultraviolet rays while heating the liquid crystal layer at a temperature not lower than the nematic phase-isotropic phase transition point of the liquid crystal material and not higher than 140 ° C. 14. A method for producing a liquid crystal display device according to 14.