JPH09258189A - Liquid crystal display device and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the response characteristics and voltage holding charactristics by incorporating a photopolymerizable resin and a photoinitiator having polymerizable groups in the molecule in a polymer wall. SOLUTION: This device consists of a pair of glass substrates 1, 2 and a liquid crystal layer held between the substrates. The liquid crystal layer has plural number of liquid crystal regions 8 each surrounded by a polymer wall 7. The polymer wall 7 consists of a photopolymerizable resin. The liquid crystal region 8 is substantially surrounded by the polymer wall 7 and both substrates 1, 2. A desired pattern of transparent electrode is formed on each surface of the substrate 1, 2 facing the liquid crystal layer. The liquid crystal molecules 9 in the liquid crystal region 8 have axial symmetry and twisted orientation. In this method, in order to decrease the residual amt. of the photopolymn. initiator in the liquid crystal, it is effective to use a photopolymn. initiator having polymerizable functional groups in the molecule. As a result, the possibility of the presence of residual photopolymn. initiator as a low mol.wt. compd. in the liquid crystal region or in the polymer region can be decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a personal display device such as a word processor or personal computer,
The present invention relates to a liquid crystal display device that is preferably used for a device used by a large number of people such as a mobile information terminal.

[0002]

2. Description of the Related Art Conventionally, the following are known as a liquid crystal display device using a composite material of liquid crystal and polymer.

A liquid crystal region is included in a matrix in a polymer, and a change in the refractive index of the liquid crystal due to application of a voltage is utilized to make a switching between a transparent state and a scattering state due to the matching of the refractive index between the liquid crystal and the polymer. By doing so, a polymer dispersed liquid crystal (PDLC) display device for displaying is disclosed in Japanese Patent Publication No. 58-501631.

Further, a liquid crystal display device obtained by irradiating a precursor mixture of a liquid crystal and a photopolymerizable resin with ultraviolet rays to three-dimensionally phase-separate the liquid crystal and the polymer, is disclosed in Japanese Patent Publication No. 6-96.
No. 1-502128.

These devices are basically scattering mode liquid crystal display devices that perform display by electrically controlling the change in the state between scattering and transparency due to the difference in refractive index between the liquid crystal and the polymer. .

[0006] In order to make the spatial distribution of the liquid crystal region of the liquid crystal layer produced by irradiating the precursor mixture of the liquid crystal and the photopolymerizable resin with ultraviolet light regular, a photomask is applied when the precursor mixture is irradiated with ultraviolet light. A method of using is disclosed below.

Japanese Unexamined Patent Publication No. 1-269922 discloses a method in which a precursor mixture of a liquid crystal and a photopolymerizable resin is passed through a photomask through a precursor mixture.
It discloses a method of forming regions having different electro-optical characteristics by performing the second exposure and further irradiating ultraviolet rays excluding the photomask and further irradiating the portion shielded by the photomask with ultraviolet rays. The liquid crystal display device obtained by this method is basically a scattering mode display device. In these scattering mode liquid crystal display devices, droplet-shaped liquid crystal regions are spatially randomly formed.

JP-A-5-257135 discloses that a precursor mixture of a liquid crystal and a photopolymerizable resin is injected between two substrates with an alignment film having an alignment regulating force, and ultraviolet rays are irradiated through a photomask. A liquid crystal device manufactured thereby is disclosed.

Further, it has been studied to provide a wide viewing angle liquid crystal display device using a composite material of liquid crystal and polymer. In order to improve the viewing angle characteristics of the liquid crystal display device, it is preferable to align the liquid crystal molecules in two or more directions on at least one substrate in the picture element.

The viewing angle characteristics of the liquid crystal display device will be described with reference to FIGS. 1 (a) and 1 (b). (A) is a liquid crystal display device in which liquid crystal molecules 9 in a pixel are oriented in at least two directions, and (b) is a voltage application in a conventional TN (twisted nematic) liquid crystal display device. FIG. 6 is a schematic diagram for explaining the relationship between the change in the orientation of liquid crystal molecules and the viewing angle characteristics in accordance with FIG. The liquid crystal layer sandwiched between the pair of substrates 1 and 2 of the liquid crystal display device of (a) has a polymer wall 7 and a liquid crystal region 8 surrounded by the polymer wall 7. The liquid crystal molecules 9 in the liquid crystal region 8 are oriented axially symmetrically about the axis of symmetry 6.

In the conventional TN orientation state, there is only one orientation direction in the halftone state shown in the middle part of FIG. 1 (b). Therefore, the physical property values relating to display characteristics such as brightness and apparent refractive index are different between when the liquid crystal molecules are viewed from the viewing angle direction of arrow A and when viewed from the direction of arrow B. On the other hand, in the liquid crystal display device of FIG. 1A, the apparent refractive index of the liquid crystal molecules is the average refractive index when viewed from both directions of arrows A and B, and therefore, in each viewing angle direction. The transmittances are averaged and equalized, and as a result, the viewing angle characteristics are improved as compared with the TN mode of FIG. FIG. 1 (b)
Shows a cross section including the axis of symmetry of a liquid crystal region having an axially symmetric alignment, so only two alignment directions are shown in the halftone state, but in reality, the apparent refractive index of the axially symmetric liquid crystal molecules is shown. The results obtained by averaging all are observed. Therefore, in order to improve the viewing angle characteristics of the conventional TN mode liquid crystal display device, the alignment direction of the liquid crystal molecules may be two or more, but the axially symmetric alignment is more preferable.

The following have been disclosed as liquid crystal display devices of wide viewing angle mode.

JP-A-4-338923 and JP-A-4-212928 disclose liquid crystal display devices of wide viewing angle mode in which the above-mentioned polymer dispersed liquid crystal device and polarizing plates orthogonal to each other are combined. There is.

Japanese Unexamined Patent Publication (Kokai) No. 5-27242 discloses a method of improving the viewing angle characteristics of a non-scattering type liquid crystal cell using a polarizing plate by separating a liquid crystal and a photopolymerizable resin from a precursor mixture by phase separation. A method for forming a liquid crystal layer made of a composite material with a molecular material is disclosed. According to this method, the orientation state of the liquid crystal domains becomes random depending on the generated polymer, and the rising directions of the liquid crystal molecules differ in each domain when a voltage is applied, so the apparent transmittance seen from each direction is Since they are equal, the viewing angle characteristics in the halftone state are improved.

The inventors of the present invention disclosed in Japanese Patent Laid-Open No. 6-301015.
In JP-A-7-120728 and JP-A-7-120728, by controlling the light intensity distribution with a photomask or the like during photopolymerization, liquid crystal molecules are brought into an axially symmetric orientation state within a pixel region, and the voltage applied to the liquid crystal molecules is controlled. As a result, a liquid crystal device having a significantly improved viewing angle characteristic is disclosed, which operates so as to change an axially symmetric orientation (such as a spiral orientation) into a homeotropic state.

In the conventional method of forming a polymer wall by photopolymerization from a precursor mixture of the above liquid crystal and photopolymerizable resin, Igacur is used as a photopolymerization initiator (initiator).
A photopolymerization initiator such as e651 or Irgacure 184 (manufactured by Ciba Geigy) was used.

[0017]

The above-mentioned photopolymerization initiator is
The molecule is cleaved by the light irradiation and becomes a radical to cause a radical reaction with the photopolymerizable resin (monomer). However, since the conventional photopolymerization initiator does not have a polymerizable functional group in the molecule, all the photopolymerization initiators do not react and remain unreacted in the system. A part of the cleavage end which becomes a radical by light irradiation reacts with the photopolymerizable resin to initiate radical polymerization and is incorporated as a terminal part of the polymer, but not all of it is incorporated. Compounds that are not incorporated into the polymer (photopolymerization initiator and radicals generated by cleavage of the photopolymerization initiator) are mixed as impurities in the liquid crystal region, so the T _NI point (nematic-isotropic) of the liquid crystal material is included. Liquid liquid transition point), decrease the response speed of liquid crystal molecules (prolong the response time),
Further, it becomes a cause of lowering the voltage holding ratio (specific resistance).
When the T _NI point is lowered, the upper limit of the temperature at which the liquid crystal display device normally operates is lowered, which is not preferable. In addition, a decrease in response speed and a decrease in voltage holding characteristic lead to a decrease in display quality.

Further, a liquid crystal region substantially surrounded by a polymer wall is regularly arranged with respect to a pixel region, and a change in polarization state of transmitted light caused by a change in orientation of liquid crystal molecules is utilized for display. In the mode (TN, STN, ECB, FLC, axisymmetric alignment) liquid crystal display device, as compared with the above-mentioned scattering mode polymer dispersion liquid crystal display mode liquid crystal display device,
The alignment state of liquid crystal molecules in the liquid crystal region greatly affects the display quality. If impurities are contained in the liquid crystal region, there is a problem that the uniformity of alignment is deteriorated, alignment defects are generated, and the display quality is deteriorated. In particular, when the liquid crystal display device of the axially symmetric mode is stored at a temperature higher than the temperature at which an isotropic phase is observed in a display region made of a mixture of a polymer material and a liquid crystal material, there is a problem that alignment failure occurs in the liquid crystal region. is there.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a liquid crystal-polymer composite liquid crystal display device having excellent response characteristics and voltage holding characteristics and a method for manufacturing the same. To provide.

[0020]

A liquid crystal display device of the present invention comprises a pair of substrates, at least one of which is transparent, and a plurality of substrates which are sandwiched between the pair of substrates and which are substantially surrounded by a polymer wall. A liquid crystal display device having a liquid crystal layer in which a liquid crystal region is regularly formed, wherein the polymer wall contains a photocurable resin and a photoinitiator having a polymerizing group in the molecule, whereby The purpose is achieved.

The alignment state of the liquid crystal molecules in the liquid crystal region is
It may be axisymmetric.

An alignment film may be provided on the liquid crystal layer side surface of at least one of the pair of substrates.

The alignment state of liquid crystal molecules in the liquid crystal region is twisted nematic type (TN), super twisted nematic type (STN), electric field control birefringence type (ECB), or ferroelectric liquid crystal type (FLC). It may be any of the above orientations.

The liquid crystal region may be formed for each picture element region which is a minimum unit for displaying.

In the method of manufacturing a liquid crystal display device of the present invention, a pair of substrates, at least one of which is transparent, and a plurality of liquid crystal regions sandwiched between the pair of substrates and substantially surrounded by polymer walls are provided. A method for manufacturing a liquid crystal display device having a regularly formed liquid crystal layer, comprising a precursor containing a photocurable resin, a liquid crystal material, and a photoinitiator having a polymerization group in the molecule, between the pair of substrates. It includes the steps of injecting a body mixture and irradiating the precursor mixture with light to form the liquid crystal layer, whereby the above object is achieved.

The light irradiation step is a step of irradiating light having a spatially regular pattern intensity distribution to regularly form the plurality of liquid crystal regions substantially surrounded by the polymer wall. May be included.

Before the step of injecting, a step of forming walls having a grid shape lower than the cell thickness on at least one of the pair of substrates may be further included.

Before the light irradiation step, the method further includes the step of controlling the temperature of the precursor mixture to cause phase separation.
The light irradiation step may be a step of light irradiation in a state where the precursor mixture is phase-separated.

In the light irradiation step, light irradiation may be performed while applying a voltage to the precursor mixture.

Hereinafter, the operation will be described.

The photopolymerization initiator used for forming the liquid crystal layer of the liquid crystal display device of the present invention has a polymerizable functional group in the molecule and forms a polymer region (polymer wall) surrounding the liquid crystal region. It acts as an initiator of the photopolymerization reaction of the photopolymerizable resin and polymerizes with the photopolymerizable resin. Therefore, the photopolymerization initiator of the present invention, by the polymerization reaction with the photopolymerizable resin,
It is fixed to the polymer wall. As a result, the photopolymerization initiator is less likely to remain as a low-molecular compound in the liquid crystal region or the polymer region.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have arrived at the present invention as a result of extensive studies on the structure of a photopolymerization initiator that does not remain in the liquid crystal region of a liquid crystal layer made of a liquid crystal-polymer composite material.
Hereinafter, embodiments of the present invention will be described.

(Structural Factor of Photopolymerization Initiator) In order to reduce the residual amount of the photopolymerization initiator in the liquid crystal, it is effective to use a photopolymerization initiator having a polymerizable functional group in the molecule. is there. Like the photopolymerizable monomer, the photopolymerization initiator having a polymerizable functional group in the molecule is incorporated into the polymer by radical polymerization (chemically bound to the polymer chain formed by the photocuring reaction). That is, even if the radical generated by light irradiation does not participate in the initiation of the polymerization reaction of the photopolymerizable monomer (due to a side reaction) and remains in the liquid crystal, the polymerization reaction of the polymerizable functional group causes photopolymerization. Like the monomer, it is incorporated into the polymer. The mechanism of incorporation of a photopolymerization initiator having a polymerizable functional group into a polymer includes a mechanism in which a radical generated by cleavage is bonded to the end of a polymer chain as an initiation end of radical polymerization, a photopolymerization initiator or a photopolymerization initiator. The reaction of a photopolymerization initiator or a photopolymerization initiator has a mechanism in which a polymerizable functional group contained in the molecule of a compound such as a radical generated by cleavage of an initiator is bound to a polymer chain by radical polymerization. The amount of the compound generated in the liquid crystal remains extremely in the liquid crystal.

The polymerizable functional group is a functional group which can be polymerized by radical reaction, and CH ₂ ═CH—, C
_{H 2 = CHCOO-, CH 2 =} C (CH 3) COO-, epoxy group and the like. The position where these functional groups are present in the photopolymerization initiator molecule may be either one or both of the cleavage ends R ₁ and R ₂ of the photopolymerization initiator in the reaction formula shown below.

Reaction formula R ₁ −R ₂ → R ₁ · + R ₂ · In addition to the above, JP-A-5-230122 and JP-A-6-122122
The photopolymerization initiator disclosed in JP-A-110039 can also be used. However, as the polymerizable functional group, CH ₂ ═CH— and CH ₂ ═CH from the viewpoint of the polymerization rate and the polymerization rate.
_{COO-, CH 2 = C (CH} 3) COO- is preferred.

(Driving Method) The liquid crystal display device of the present invention can be driven by various driving methods. That is, simple matrix drive, a-Si (amorphous silicon) TFT (thin film transistor), p-Si (polysilicon) TFT, M
A driving method such as active driving using a switching element such as an IM (Metal-Insulator-Metal) element can be used.

(Substrate Material) As the substrate material, glass which is a transparent solid, a polymer film or the like can be used, and as the opaque solid, a substrate with a metal thin film aiming at a reflection type or a semiconductor substrate such as Si can be used.

As the plastic substrate, a material having no absorption of visible light is preferable, and PET (polyethylene terephthalate), acrylic polymer, polystyrene,
Polycarbonate or the like can be used.

Furthermore, it is possible to fabricate a cell by combining substrates made of different materials, and it is also possible to use two substrates having different substrate thicknesses regardless of whether they are of the same kind or different kinds. In the case of a plastic substrate, a liquid crystal display device in which a polarizing plate is integrated can be manufactured by making the substrate itself have a polarizing ability.

[0040]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited thereto.

Example 1 and Comparative Example 1 The liquid crystal display device 10 of this example has a pair of glass substrates 1 and 2 and a liquid crystal layer sandwiched therebetween, as shown in FIG. have. The liquid crystal layer has a plurality of liquid crystal regions 8 substantially surrounded by the polymer wall 7, and the polymer wall 7 is formed of a photopolymerizable resin. In this embodiment, the liquid crystal region 8 is substantially surrounded by the polymer wall 7 and both substrates 1 and 2. Further, transparent electrodes (not shown) having desired patterns are formed on the surfaces of the substrates 1 and 2 on the liquid crystal layer side. The liquid crystal molecules 9 in the liquid crystal region 3 are twisted while having axial symmetry. Here, the twist angle is 9
It was set to 0 °. In this embodiment, the transmissive liquid crystal display device 10 is constructed. However, when a reflective liquid crystal display device is constructed, an opaque substrate such as a semiconductor substrate can be used as one substrate. Further, in the present embodiment, one liquid crystal region is formed for each picture element region. However, when a long picture element (aspect ratio of the picture element is different) is used, a plurality of liquid crystals are provided for one picture element region. Regions may be formed. Also in this case, the liquid crystal regions are spatially regularly arranged.

Next, a method of manufacturing the liquid crystal display device 10 will be described.

Two 1.1 mm thick glass substrates 1 and 2 having a transparent electrode of a desired pattern made of ITO (a mixture of indium oxide and tin oxide, 50 nm) were used, and a cell was formed by a spacer (not shown) of 5 μm. The cell was constructed by maintaining the thickness. In this embodiment, a known method is used to form an active matrix type liquid crystal cell.

In the obtained cell, 0.08 g of isobornyl acrylate and 0.04 of R-684 (manufactured by Nippon Kayaku Co., Ltd.)
g, p-phenylstyrene 0.04 g, further liquid crystal material ZLI-4792 (manufactured by Merck & Co., Inc., chiral pitch adjusted to be 90 ° between cells, used) 0.8
A precursor mixture obtained by uniformly mixing 4 g and 0.005 g of a photopolymerization initiator A having a structure represented by the following (Chemical formula 1) was injected by a vacuum injection method.

[0045]

(Initiator A)

A shading region 2 shown in FIG. 2 is formed on the manufactured cell.
0a and a photomask 20 having a transmissive region 20b are arranged, and then a frequency of 60 Hz and an amplitude of ± 4 V are applied between the transparent electrodes.
100 mm at 8 mW / cm ² under a high pressure mercury lamp that can obtain parallel rays from the photomask side while applying the voltage of
Irradiation was conducted at 8 ° C for 8 minutes. In this way, the precursor mixture in the cell can be irradiated with ultraviolet light having a spatially regular pattern of intensity distribution. The temperature of the above light irradiation step is preferably the compatibilizing temperature of the precursor mixture or higher, and the temperature of T _NI point or lower of the liquid crystal phase after phase separation. In the process of forming the liquid crystal phase by the photopolymerization-induced phase separation, an electric field is applied to the liquid crystal phase to stabilize the alignment of the liquid crystal molecules.

After that, at a voltage of 25 ° C.
(Liquid crystal is in nematic state) Gradually cool the cell (10
(Cooling rate of ° C / hr), and the resin was further cured by irradiating the entire surface with ultraviolet light for 3 minutes continuously without a mask.

When the obtained liquid crystal cell was observed with a polarization microscope, as shown in FIG. 3, the polymer wall 7 and the liquid crystal region 8 were formed substantially at the position corresponding to the pattern of the photomask. Further, since the radial extinction pattern 5 was observed in the liquid crystal region 8, it was found that the liquid crystal region 8 was in an axially symmetrical alignment state around the axis near the center. In the axisymmetric alignment, liquid crystal molecules whose molecular axis is parallel to the polarization axis of the polarizing plate and liquid crystal molecules whose molecular axis is tilted with respect to the polarization axis are
It exists continuously. As a result, a radial extinction pattern is observed.

Table 1 shows the results of evaluation of the characteristics of the liquid crystal display device obtained by laminating polarizing plates on the produced cells so that their polarization axes were orthogonal to each other. Example 1 above except that Irgacure 651 was used as the photopolymerization initiator.
A liquid crystal display device manufactured in the same manner as in Comparative Example 1 was used.

The conditions for evaluating the characteristics of the liquid crystal display device are shown below.

Response time (response speed): voltage 0-5V
And the time required for the relative transmittance to change by 90% was measured. Time required for transmittance to increase τ
It was evaluated by the sum of r and the time τd required for the transmittance to decrease.

T _NI point in liquid crystal region: temperature rising rate 0.5 ° C.
The temperature at which the isotropic liquid phase appeared in the nematic phase was measured by observing with a polarizing microscope while raising the temperature at / min.

Voltage holding ratio: pulse width 5 μsec, amplitude 5 V
After the pulse voltage was applied, the ratio of the potential held for 16.5 msec was measured.

[0054]

[Table 1]

As is clear from the results in Table 1, the response speed of the liquid crystal display device of Example 1 using the photopolymerization initiator A,
The T _NI point and the voltage holding ratio are superior to those of the liquid crystal display device of Comparative Example 1 using the conventional photopolymerization initiator.

Example 2 and Comparative Example 2 In this example, a resist wall was formed in advance in a region where the polymer wall of one substrate was formed, and irradiation with ultraviolet rays was performed without using a mask. The same as in Example 1. In this embodiment, the resist is used to form the wall, but other materials may be used to form the wall. For example, the wall can also be formed by forming a resist layer having a pattern on a non-photosensitive polymer film and etching the polymer film using this resist layer as a mask.

The liquid crystal display device of this embodiment can be manufactured as follows. Also in this embodiment, an active matrix type liquid crystal display device is formed similarly to the first embodiment.

I was placed on two glass substrates with a thickness of 1.1 mm.
A transparent electrode having a desired pattern made of TO (mixture of indium oxide and tin oxide, thickness: 50 nm) was formed. As shown in FIG. 4, a resist wall 42 (manufactured by OMR83: manufactured by Tokyo Ohka Kogyo Co., Ltd.) containing a spacer 41 of 5 μm was formed on one of the substrates so that the height was 2.7 μm. A cell was constructed by bonding the produced substrate and the other substrate with an adhesive seal. In the resulting cell, 0.04 g of isobornyl acrylate, R
-684 (Nippon Kayaku Co., Ltd.) 0.02 g, p-phenylstyrene 0.02 g, and further liquid crystal material ZLI-4792
(Merck & Co., Inc., chiral pitch was adjusted to 90 ° between cells and used.) 0.92 g and the above-mentioned photopolymerization initiator A 0.005 g were uniformly mixed to obtain a precursor mixture, It was injected by the vacuum injection method.

Thereafter, the phase separation of the precursor mixture is controlled by temperature control so that the liquid crystal regions formed in the region surrounded by the resist wall 42 become one, and a voltage is further applied to the liquid crystal region. , The liquid crystal molecules in the liquid crystal region formed by phase separation are oriented in axial symmetry. After that, it was cooled to room temperature, and 4 mW / cm ² under a high pressure mercury lamp.
Then, the precursor mixture in the cell was irradiated with ultraviolet rays for 20 minutes. Furthermore, in order to completely cure the resin, 4 m
Ultraviolet light of W / cm ² was continuously irradiated at room temperature for 10 minutes.

When the obtained cell was observed with a polarization microscope, it was observed that it had the same axially symmetric orientation as in Example 1. A polarizing plate was attached to the manufactured cell in the same manner as in Example 1, and the results of evaluating the characteristics of the obtained liquid crystal display device are shown in Table 2. The method for evaluating the characteristics is the same as in Example 1.

Irgacure65 as a photopolymerization initiator
A liquid crystal display device manufactured in the same manner as in Example 2 except that 1 was used was set as Comparative Example 2.

[0062]

[Table 2]

As can be seen from Table 2, the response speed of the liquid crystal display device of Example 2 using the photopolymerization initiator A, T
_{The NI} point and the voltage holding ratio are superior to those of the liquid crystal display device of Comparative Example 2 using the conventional photopolymerization initiator.

Example 3 and Comparative Example 3 (TN Mode) FIG. 5 is a sectional view of the liquid crystal display device 50 of this example. The liquid crystal display device 50 is substantially the same as the liquid crystal display device of Example 1 except that the alignment of the liquid crystal molecules 9 in the liquid crystal region 8 is the TN alignment. In order to obtain the TN alignment, the alignment film 1b is provided on the side of the substrates 1 and 2 which is in contact with the liquid crystal layer,
2b is formed and rubbed in a predetermined direction.

The liquid crystal display device 50 of this embodiment is manufactured as follows.

On a 1.1 mm thick glass substrate having transparent electrodes 1a and 1b of desired pattern made of IT0 (mixture of indium oxide and tin oxide, 50 nm),
A polyimide film (AL4552: manufactured by Nippon Synthetic Rubber Co., Ltd.) was applied using a spin coating method, and a rubbing treatment was performed using a nylon cloth. The two substrates thus produced were attached to each other via a spacer (not shown) of 5 μm so that the rubbing directions were orthogonal to each other.

In the prepared cell, 0.04 g of isobornyl acrylate, 0.02 g of R-684, 0.02 g of p-phenylstyrene, and further liquid crystal material ZLI-479.
2 (manufactured by Merck) and 0.92 g of the above-mentioned photopolymerization initiator A
The precursor mixture obtained by uniformly mixing 0.005 g was
It was injected by the vacuum injection method. The liquid crystal material ZLI-4792 used in this example was adjusted and used so that the chiral pitch was 80 μm. In the TN mode, since the twist angle of the liquid crystal molecules is defined by the alignment regulating force (rubbing direction) of the substrate, a long-pitch nematic liquid crystal having excellent display characteristics was used.

Thereafter, the photomask 20 shown in FIG. 2 was placed on the obtained cell, and the polymer wall 7 was formed in the same manner as in Example 1.
A TN-mode cell having a liquid crystal region 8 surrounded by was produced. A polarizing plate was attached to each of the substrates so that the polarization axis of each substrate coincided with each rubbing direction of the obtained cell to obtain a liquid crystal display device.

The liquid crystal molecules 9 in the liquid crystal region 8 of the manufactured liquid crystal display device 50 were in TN alignment and were in a uniform alignment state. Furthermore, the display characteristics did not change even if the display surface was pressed with a pen. The results of evaluation of response speed are shown in Table 3 together with the results of Comparative Example 3 below.

Irgacure65 as a photopolymerization initiator
A liquid crystal display device manufactured in the same manner as in Example 3 except that 1 was used was set as Comparative Example 3.

As is clear from Table 3, the response speed was remarkably improved by using the photopolymerization initiator having a polymerizable functional group according to the present invention as in Examples 1 and 2.

[0072]

[Table 3]

Example 4, Comparative Example 4 (STN Mode) This example is substantially the same as the liquid crystal display device of Example 1 except that the liquid crystal region of the liquid crystal display device has the STN alignment. Are the same. In this embodiment, a liquid crystal display device for simple matrix driving is constructed.

The liquid crystal display device of this embodiment is manufactured as follows.

A polyimide film (San Ever: Nissan Chemical Co., Ltd.) was spin-coated on a 1.1 mm-thick glass substrate having a stripe-shaped transparent electrode made of ITO (a mixture of indium oxide and tin oxide, 50 nm). It was applied and rubbed with a nylon cloth.
9 μ of the two substrates thus produced so that the striped electrodes are orthogonal to each other and the rubbing directions are 240 ° to each other.
It pasted together via the spacer of m.

Isobornyl acrylate 0.04 g and R-684 (manufactured by Nippon Kayaku Co., Ltd.) 0.02 were placed in the obtained cell.
g, p-phenylstyrene 0.02 g, liquid crystal material ZLI-4427 (Merck & Co., Inc .: chiral pitch was adjusted to 240 ° between cells, and used).
A precursor mixture obtained by uniformly mixing 92 g and 0.005 g of photopolymerization initiator A was injected by a vacuum injection method.

Then, in the same manner as in Example 1, an STN mode cell having a liquid crystal region surrounded by polymer walls was prepared.

A polarizing plate was attached to the produced cell so that the polarization axes were 45 ° from the rubbing direction and 105 ° to each other, to produce a liquid crystal display device.

The liquid crystal molecules in the liquid crystal region of the manufactured liquid crystal display device were in STN alignment and were in a uniform alignment state. Furthermore, the display characteristics did not change even if the display surface was pressed with a pen. The results of evaluation of the response speed are shown in Table 4 together with the results of Comparative Example 4 below.

Irgacure65 as a photopolymerization initiator
A liquid crystal display device manufactured in the same manner as in Example 3 except that 1 was used was set as Comparative Example 3.

As is clear from Table 4, the above Examples 1 to 1
Similar to 3, the response speed was remarkably improved by using the photopolymerization initiator having a polymerizable functional group according to the present invention.

[0082]

[Table 4]

In addition, the orientation of liquid crystal molecules in the liquid crystal region can be homogenous orientation, homeotropic orientation, or hybrid orientation to display an electric field control birefringence mode. In the specification of the present application, the orientation of liquid crystal molecules for displaying an electric field control birefringence mode is generically called ECB.
This is called mold orientation.

Example 5 and Comparative Example 5 (FLC) This example was carried out except that a surface-stabilized ferroelectric liquid crystal (SSFLC) was used as the liquid crystal forming the liquid crystal region of the liquid crystal display device. This is substantially the same as the liquid crystal display device of Example 1. In this embodiment, a liquid crystal display device for simple matrix driving is constructed.

The liquid crystal display device of this embodiment is manufactured as follows.

A polyimide film (San Ever: Nissan Chemical Co., Ltd.) was spin-coated on a 1.1 mm-thick glass substrate having a transparent electrode in a stripe pattern made of ITO (a mixture of indium oxide and tin oxide, 50 nm). It was applied and rubbed with a nylon cloth.
2 μm so that the striped electrodes are orthogonal to each other and the rubbing directions are orthogonal to each other on the two substrates thus produced.
It pasted together through the spacer of.

In the obtained cell, 0.03 g of polyethylene glycol diacrylate (NK ester A-200, manufactured by Shin-Nakamura Chemical Co., Ltd.) and 0.1 lauryl acrylate were used.
4 g, styrene 0.03 g, and liquid crystal material ZLI-4
A precursor mixture obtained by uniformly mixing 0.80 g of 003 (manufactured by Merck & Co., Inc.) and 0.005 g of the photopolymerization initiator A was injected by a vacuum injection method.

After that, the photomask shown in FIG. 2 was placed on the fabricated cell, and in the same manner as in Example 1, the FLC mode (SSF type: SSF type:
A surface-stabilized ferroelectric liquid crystal type cell) was prepared.
A polarizing plate was attached to the produced cell so that the polarization axes thereof were 90 ° with each other, to produce a liquid crystal display device.

When observed with a polarizing microscope, the produced cell was in SSF orientation and was in a uniform orientation state. Furthermore, the display characteristics did not change even when the display surface was pressed with a pen. Furthermore, the alignment disorder due to the external force that occurs in a normal FLC mode cell did not occur even when the cell was pressed.

Irgacure65 as a photopolymerization initiator
A liquid crystal display device produced in the same manner as in Example 5 except that 1 was used was set as Comparative Example 5. Similar to Examples 1 to 4, the response speed was remarkably improved by using the photopolymerization initiator having the polymerizable functional group according to the present invention.

[0091]

As described above, according to the present invention, in the liquid crystal display device having the liquid crystal layer in which the liquid crystal region is substantially surrounded by the polymer wall, the degree of polymerization of the photopolymerizable resin constituting the polymer wall ( LCD T _NI point of reactivity) and a liquid crystal region is increased, the liquid crystal display device and a manufacturing method thereof excellent in response speed and voltage holding ratio is provided. The liquid crystal display device of the present invention is particularly preferably used in the following fields.

Since the liquid crystal region is surrounded by the polymer wall, it is possible to suppress the deformation of the liquid crystal display device due to an external force, and especially to suppress the color change at the time of pen input. Further, in the conventional large-screen display device, the cell thickness is different due to gravity between the upper part and the lower part of the display device, resulting in display unevenness. Since they are adhered, the cell thickness is unlikely to change and a uniform display can be provided.

By effectively utilizing the phase separation between the liquid crystal and the photopolymerizable resin, the alignment state of the liquid crystal region can be oriented in axial symmetry (concentric circles, radials, spirals, etc.), and the viewing angle characteristics can be improved. An excellent liquid crystal display device can be manufactured. Further, the compound of the present invention can enhance the alignment regulating force at the liquid crystal-polymer interface. This is because the alignment control force is generated by the liquid crystal molecules fixed in the polymer at the liquid crystal-polymer interface, and by using the photopolymerizable initiator of the present invention, the curing reaction of the polymer is more completely achieved. It is considered that the liquid crystal molecules are more firmly fixed at the liquid crystal-polymer interface as they proceed.

A display mode in which a liquid crystal region substantially surrounded by a polymer wall is regularly arranged with respect to a pixel region and a change in polarization state of transmitted light due to a change in alignment of liquid crystal molecules is utilized ( In the liquid crystal display device of TN, STN, ECB, SSFLC, and axisymmetric alignment), a liquid crystal region (liquid crystal droplets) is randomly formed, as compared with a conventional liquid crystal display device of polymer dispersion type liquid crystal display mode of scattering mode. The alignment state of liquid crystal molecules in the liquid crystal region greatly affects the display quality. Therefore, since the amount of the photopolymerization initiator contained as an impurity in the liquid crystal region is reduced, the alignment of the liquid crystal molecules in the liquid crystal region is stabilized, and alignment defects are less likely to occur, resulting in a liquid crystal display having excellent display quality. A device can be provided. Furthermore, the phase separation is brought close to perfection,
By increasing the T _NI point of the liquid crystal in the liquid crystal region, it is possible to prevent the problem of alignment failure occurring in the liquid crystal region when the liquid crystal display device of the axially symmetric mode is stored at high temperature.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating the principle of widening the viewing angle by a liquid crystal display device of the present invention. (A) is a sectional view of a liquid crystal display device according to the present invention, and (b) is a sectional view of a conventional TN type liquid crystal display device.

FIG. 2 is a schematic view showing a photomask used in Example 1 of the present invention.

FIG. 3 is a schematic view showing a result of observing the liquid crystal display device of Example 1 with a polarization microscope.

FIG. 4 is a schematic view of a substrate having a resist wall mixed with beads used in Example 2.

FIG. 5 is a schematic view showing a cross section of a liquid crystal display device of Example 3.

[Explanation of symbols]

 1, 2 substrate 5 extinction pattern 6 symmetry axis 7 polymer wall 8 liquid crystal region 9 liquid crystal molecule 10 liquid crystal display device 20 mask 20a light shielding region 20b light transmissive region 41 beads 42 resist wall 50 liquid crystal display device 51, 52 substrate 51a, 52a transparent Electrodes 51b, 52b Alignment film

Claims (10)

[Claims] 1. A pair of substrates, at least one of which is transparent, and a liquid crystal layer which is sandwiched between the pair of substrates and in which a plurality of liquid crystal regions substantially surrounded by polymer walls are regularly formed. ,
A liquid crystal display device comprising: a polymer wall containing a photocurable resin and a photoinitiator having a polymerizing group in the molecule. 2. The liquid crystal display device according to claim 1, wherein the alignment state of the liquid crystal molecules in the liquid crystal region is axially symmetrical. 3. The liquid crystal display device according to claim 1, further comprising an alignment film on a surface of at least one of the pair of substrates on the liquid crystal layer side. 4. The alignment state of liquid crystal molecules in the liquid crystal region is:
4. The liquid crystal according to claim 3, wherein the liquid crystal has a twisted nematic type (TN), a super twisted nematic type (STN), an electric field control birefringence type (ECB), or a ferroelectric liquid crystal type (FLC) alignment. Display device. 5. The liquid crystal display device according to claim 1, wherein the liquid crystal region is formed for each picture element region which is a minimum unit for displaying. 6. A pair of substrates, at least one of which is transparent,
A liquid crystal layer sandwiched between the pair of substrates, in which a plurality of liquid crystal regions substantially surrounded by a polymer wall are regularly formed,
And a step of injecting a precursor mixture containing a photocurable resin, a liquid crystal material, and a photoinitiator having a polymerization group in the molecule between the pair of substrates, Irradiating the precursor mixture with light to form the liquid crystal layer, and a method for manufacturing a liquid crystal display device. 7. The light irradiating step irradiates light having a spatially regular pattern intensity distribution to regularly form the plurality of liquid crystal regions substantially surrounded by the polymer wall. The method for manufacturing a liquid crystal display device according to claim 6, which includes the steps. 8. The liquid crystal display according to claim 7, further comprising a step of forming walls having a grid shape lower than a cell thickness on at least one substrate of the pair of substrates before the injecting step. Device manufacturing method. 9. The method further comprises the step of controlling the temperature of the precursor mixture and performing phase separation before the light irradiation step, wherein the light irradiation step comprises the step of phase-separating the precursor mixture, The method for manufacturing a liquid crystal display device according to claim 8, which is a step of irradiating with light. 10. The method of manufacturing a liquid crystal display device according to claim 9, wherein in the light irradiation step, light irradiation is performed while applying a voltage to the precursor mixture.