JP2001272682A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device in which the aligning property of the liquid crystal and storage property of the display quality are improved with respect to a liquid crystal device which uses a photoalignment method. SOLUTION: The liquid crystal display device has a liquid crystal display cell manufactured by a photoalignment method and at least one member having UV absorptivity disposed between the photoalignment layer of the liquid crystal display cell nearest to the observation side and the outermost surface in the observation side.

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 in which a member or a material having an ultraviolet absorbing ability is incorporated in a liquid crystal device manufactured by a photo-alignment method.

[0002]

2. Description of the Related Art A liquid crystal display device has a structure in which liquid crystal is sealed between a pair of transparent substrates spaced at a predetermined interval. That is, the liquid crystal molecules have anisotropy of the refractive index, and form a pixel from a difference between a state where the liquid crystal molecules are aligned along the direction of the voltage applied to the liquid crystal and a state where no voltage is applied. be able to. An alignment film is formed on the substrate to align liquid crystal molecules. A polymer material typified by polyimide is used for the alignment film. For example, a liquid crystal display in which an alignment film is formed by rubbing the polymer material with a cloth or the like to give an alignment direction (so-called rubbing). There is a device. In this liquid crystal display device, the liquid crystal molecules are aligned in the rubbing direction of each alignment film of the pair of substrates. Normally, TN mode liquid crystal cells are opposed so that the rubbing directions of a pair of substrates cross each other, so that the liquid crystal molecules are spirally arranged from one substrate to the other substrate.

When a halftone between a black level and a white level is displayed, the liquid crystal molecules are obliquely aligned with respect to the substrate by the balance between the electric field and the force from the alignment film. For this reason, the apparent angle of the liquid crystal molecules with respect to the substrate differs depending on the viewing angle, and the brightness looks different. Also, in the case of color display, they appear as different colors.

For this reason, in recent liquid crystal display devices, in order to improve visual characteristics such as obtaining a high contrast at a wide viewing angle, one pixel is divided into a plurality of pixels, and the liquid crystal is controlled by an electric field in each divided region. It has been proposed to form a liquid crystal display device by a method called multi-domain in which the directions of inclined planes are respectively changed.

[0005] In this method, a mask rubbing method in which rubbing is performed while moving a mask having a predetermined shape (K.
Takatori et. al. , "A Complete
mentary TN LCD with Wide-
Viewing AngleGrayscale ", J
ap. Display '92, pp591), a method of applying a plurality of alignment film materials (T. Kamada e)
t. al. , "Wide Viewing Angle
Full-Color TFT LCDs ", Japan
an Display '92, pp886), and a method of changing the characteristics of an alignment film by irradiation with ultraviolet rays or the like (Japanese Patent Laid-Open No. Hei 5
JP-A-210099). The steps and processes of the method using mask rubbing and the method of applying a plurality of alignment film materials are complicated.

Further, these methods only change the tilt angle (so-called pretilt angle) of the liquid crystal when the alignment film is formed to form two symmetrical pretilt angles, and have a single alignment direction. The improvement of the viewing angle is limited to a predetermined direction.

As a liquid crystal alignment control method other than the rubbing method, an oblique evaporation method using an oblique evaporation film of SiO or the like (Japanese Patent Application Laid-Open No. 56-68626), a photolithography method or the like is used to form a grating-like surface on the alignment film. A photolithography method for forming irregularities (JP-A-60-60624), an LB film method for orienting a polymer chain in a pulling direction during accumulation on a substrate (JP-A-62-195622), ion Ion irradiation method for obliquely irradiating an object such as
No.-83017), a high-speed liquid jet method in which a liquid is jetted obliquely at a high speed (Japanese Patent Application Laid-Open No. 63-96631), and an ice blasting method in which ice chips are jetted diagonally (Japanese Patent Application Laid-Open No.
No. 3-96630), an excimer laser method in which a polymer surface is irradiated with an excimer laser or the like to form a periodic stripe pattern (Japanese Patent Application Laid-Open No. 2-196219, etc.). An electron beam scanning method (Japanese Patent Application Laid-Open No. 4-97130, etc.) for forming fine irregularities, a centrifugal method for applying a centrifugal force to a coated alignment film solution to orient polymer chains (Japanese Patent Application Laid-Open No. 63-213819), A stamping method for transferring the orientation ability by pressing the treated base material (for example, JP-A-6-43457); The random orientation method of twisting by adding a chiral agent by Toko et al. (J. Appl. Phys. A 74 (3), p207
1 (1993)); A photodimerization method utilizing a 2 + 2 cycloaddition reaction of polyvinyl cinnamate by Schattt et al. (Jpn. J. Appl. Phys., 31Part)
1, No. 7, p2155 (1992)), Hasegawa et al., Photolysis method for photodecomposition of polyimide film with polarized ultraviolet light (Preliminary collections of Liquid Crystal Symposium, p232 (Article number 2G604))
(1994)).

On the other hand, a cell in which a diazodiamine dye is doped into a polyimide liquid crystal alignment film and a liquid crystal is aligned in a certain direction by a rubbing method is produced, and the liquid crystal on the alignment film surface is irradiated by a polarized laser beam. It is possible to change the orientation direction in the direction perpendicular to the electric field direction of the irradiated polarized light. M. Gibbons et al. (Nature, 351, p49 (1991)).
In addition, Ichimura et al. Reported that when the surface of a liquid crystal display element substrate was chemically modified with photochromic molecules, it was possible to switch between vertical and parallel alignment of liquid crystal molecules only by light irradiation, and to change the direction of parallel alignment by polarized light irradiation. (Applied Physics, 62 (10), p998 (1993), etc.).

As described above, in recent years, the photo-alignment method can provide the liquid crystal alignment by a simple method instead of the rubbing method.
Development using this technology has become active. Since the photo-alignment method basically provides the alignment ability using light, particularly ultraviolet light, the photo-alignment film is required to react to light. When a liquid crystal device is assembled using such a material, the photo-alignment film reacts in an environment where ultraviolet rays are present, and the orientation of the liquid crystal may be changed.

[0010]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in order to solve the above-mentioned problems, and is intended to provide a liquid crystal device using a photo-alignment method, which has a high ultraviolet absorbing ability. Another object of the present invention is to provide a liquid crystal display device in which the orientation of liquid crystal and the preservability of display quality are improved by incorporating materials.

[0011]

The present invention is achieved by the following means.

1. A member including a liquid crystal display cell manufactured by a photo-alignment method and provided with at least one ultraviolet absorbing ability is provided between the photo-alignment layer closest to the observation side of the liquid crystal display cell and the outermost surface of the observation side. A liquid crystal display device characterized by being performed.

2. Including a liquid crystal display cell produced by a photo-alignment method, and at least one member provided with an ultraviolet absorbing ability is provided between the photo-alignment layer closest to the backlight side and the backlight. Liquid crystal display device.

3. A liquid crystal display device comprising a liquid crystal display cell produced by a photo-alignment method, and one or more members provided with an ultraviolet absorbing ability provided on both sides of the liquid crystal display cell.

4. 4. The liquid crystal display device according to any one of the above items 1 to 3, wherein the member having an ultraviolet absorbing ability is in the form of a film.

5. 5. The liquid crystal display device according to the above item 4, wherein the resin constituting the film is a cellulose ester.

6. The liquid crystal display device according to any one of the above items 1 to 5, wherein the ultraviolet absorbing ability is provided by an organic ultraviolet absorbing agent.

[7] An optical photo-alignment film protective film comprising an organic ultraviolet absorber.

8. A member including a liquid crystal display cell manufactured by a photo-alignment method and provided with at least one ultraviolet absorbing ability is provided between the photo-alignment layer closest to the observation side of the liquid crystal display and the outermost surface of the observation side or a backlight. In a liquid crystal display device having at least one between the light alignment layer closest to the liquid crystal display and the backlight, the member provided with the ultraviolet absorbing ability is provided on the side farther than the polarizer closest to the liquid crystal panel. A liquid crystal display device characterized by the above-mentioned.

9. 9. The liquid crystal display device according to the item 8, wherein the member provided with the ultraviolet absorbing ability is a transparent resin film.

10. 10. The liquid crystal display device according to the item 9, wherein the resin of the transparent resin film is a cellulose ester.

11. Any one of the above items 8 to 10, wherein the ultraviolet absorbing ability is provided by an organic ultraviolet absorbing agent.
A liquid crystal display device according to the item.

12. 12. The liquid crystal display device according to the above item 9, 10 or 11, wherein the transparent resin film is a polarizing plate protective film.

Hereinafter, the present invention will be described in detail. As a photo-alignment method for obtaining an alignment film, the above-described technique or a generally known technique can be used. For example, photolytic type,
Hasegawa, liquid crystal, V
ol3 (1), 3-16 (1999) can be referred to. In addition, for example, photo-decomposition types are disclosed in JP-A-5-34699 and JP-A-8-122789.
No., No. 8-122792, No. 9-5747, etc.
As the photolytic type, JP-A-5-34699,
No. 122789, No. 8-122792, No. 9-57
For example, JP-A-8-304828 and JP-A-7-138 further disclose methods using a photodimerization reaction.
No. 308, No. 6-095066, No. 5-232473
No. 8-015681; No. 9-222605; No. 6-287453; No. 6-289374;
No. 0-506420, JP-A-10-324690, and JP-A-10-310613, which can be referred to.

In these methods, the liquid crystal can be provided with an orientation by irradiating the photo-alignment layer with ultraviolet rays. As a light source as a light irradiation device, an ultra-high pressure mercury lamp, a xenon lamp, a fluorescent lamp, a laser, or the like can be used. This can be combined with a polarizer to irradiate linearly polarized light. As the irradiation device, for example, the device disclosed in JP-A-10-90684 can be used.

[0026] Among the photo-alignment techniques, the photo-dimerization reaction can impart orientation to the liquid crystal even if the ultraviolet energy is relatively low as compared with the photo-decomposition type. In particular, when the photodimerization reaction is performed by irradiating linearly polarized ultraviolet light, the photodimerization reaction proceeds by selecting the polarization direction, and this contributes to the alignment of the liquid crystal. Therefore, when used as a liquid crystal device, when used in an environment where ultraviolet light is present, the liquid crystal device is exposed to non-polarized ultraviolet light in a direction other than the direction in which photodimerization has selectively reacted during the preparation of the alignment film. Since the photodimerization reaction occurs in a direction other than the orientation direction designed as, the orientation tends to be disordered. This has a significant effect on image display. Therefore, it is necessary to minimize the irradiation of the photo-alignment layer with ultraviolet rays.

The sun rays falling on the earth include infrared rays,
There are visible rays, ultraviolet rays, X-rays, gamma rays, etc., and some of the ultraviolet rays, X-rays and gamma rays do not reach the surface of the earth. Conventionally, UV-B, which has strong energy, has recently caused ozone holes to appear everywhere on the earth due to the destruction of the ozone layer due to the use of chlorofluorocarbon gas. It has reached the ground. Further, UV-A in a long wavelength region is radiated to the surface of the earth.

On the other hand, in the liquid crystal display device, various members are used around the alignment film of the liquid crystal cell. For example, a light source of a backlight, a light guide plate, a diffusion plate, a polarizing plate, a retardation plate, a glass or plastic substrate for a liquid crystal panel, an antireflection or a protection plate having a hard coat layer, and an adhesive used when combining these members. Agents and the like. When a liquid crystal display device is used, it is important to create an environment in which ultraviolet rays are not irradiated to the photo-alignment film because a lot of ultraviolet rays exist in our living environment.

On the other hand, a fluorescent lamp is generally used as a backlight. A general fluorescent lamp is a device in which ultraviolet light generated by the discharge of mercury vapor is converted into visible light by a phosphor coated on the inside of a glass tube. Yes, and emits a large amount of ultraviolet light. It cannot be said that fluorescent lamps as lighting in everyday life have no similar effect.

Therefore, when a photo-alignment film is present in the liquid crystal cell, if a member having a high ultraviolet-absorbing ability is installed on the liquid crystal image observation side and / or the backlight side with respect to the alignment film, the photo-alignment film can be obtained. Deterioration of the film due to light can be suppressed, and the retention of the alignment ability of the liquid crystal can be improved.

A known technique can be used as a technique for cutting ultraviolet rays. Such a technique is also applied to a technique used in automobiles and sunglasses, and to a plastic material.

In the present invention, a member having an ultraviolet absorbing ability may be incorporated into a liquid crystal device, and the technique for imparting the ultraviolet absorbing ability is not particularly limited. For example, dope of inorganic substances developed in ultraviolet absorbing glass and the like, a method of vapor deposition or coating on a surface, mixing, compounding, and compatibilizing a material having a high ultraviolet absorbing ability among inorganic or organic substances in a plastic member. Examples of the method include a method, a method of forming a film deposited on the surface, and a method of installing a film applied on the surface.

For example, a compound having a high ultraviolet absorbing ability can be mixed with or applied to the resin of the above member. Further, it can be processed into a film form and attached to a liquid crystal panel, or the film can be wound around a fluorescent lamp as a backlight.

Techniques for imparting these ultraviolet absorbing capabilities are disclosed in JP-A-6-166538 and JP-A-8-133791.
No., 11-111985, 11-1148932,
These techniques can be used for members used in the above-described liquid crystal device.

In the present invention, an ultraviolet absorber is applied to a polarizing plate, a polarizing plate protective film, a retardation plate, a reflector, a viewing angle compensation film, an antiglare film, an antireflection film, an antistatic film, and a hard coat film. , Or using a film containing, efficiently ultraviolet absorption ability,
It is preferable as a method that can be applied at low cost, and more preferably, it is used for a polarizing plate protective film. Thereby, the object of the present invention can be satisfied together with the stabilization of the polarizing plate.

The film used in the present invention has a characteristic that the transmittance in the visible region is 80% or more, and examples thereof include cellulose ester, polyethylene terephthalate, polycarbonate, polyarylate, and polysulfone. Among the above descriptions, cellulose ester is preferable from the viewpoint of uniformity of optical characteristics, and cellulose triacetate is more preferable.

Further, from the viewpoint of the strength of the film, those having a polymerization degree of 250 to 400 are particularly preferably used.

When an ultraviolet absorber is contained in the film, the ultraviolet absorber is preferably an organic compound from the viewpoint of compatibility with the resin constituting the film.

These techniques are described in, for example,
No. 118233, No. 6-130226, No. 6-148
No. 430, No. 6-220223, No. 6-220224
Nos. 6-235819, 7-11056, 7
Nos. -90184, 8-29619 and 8-2395
No. 09 and No. 9-166711.

At least one member having the ultraviolet absorbing ability can be provided between the light-alignment layer closest to the backlight and at least one member. It can also be designed separately.

On the other hand, a member provided with the ability to absorb ultraviolet rays
At least one member can be installed between the photo-alignment layer closest to the observation side of the display image and the surface on the observation side, and when there are two or more members, the ultraviolet absorption capacity should also be divided into these two or more members. Can also.

The absorption capacity of ultraviolet light provided by the member between the light alignment layer closest to the backlight side and the backlight and / or the light alignment layer closest to the display image observation side includes absorbance. At least 1, preferably absorbance 2
The number is more preferably 3 or more. By using two or more such members, the present invention becomes more effective.

With respect to the above-mentioned provision of the absorbance in the ultraviolet region,
The required wavelength differs depending on the photo-alignment material. Ideally, it should provide absorption in the entire ultraviolet region, but it covers wavelength regions that are highly sensitive to photochemical and / or photodecomposition reactions when giving alignment to photoalignment materials. It is efficient to do. For example, since the photodimerizable alignment film having a coumarin ring reacts by light irradiation of 280 to 320 nm, it imparts an absorptivity capable of efficiently covering this region, and absorbance of the wavelength region is 1 or more, preferably 2 or more, More preferably, it can be 3 or more.

The provision of the ability to absorb ultraviolet rays in the present invention means
This means that a member that has not been processed is deliberately given an absorption capacity using an ultraviolet-absorbing compound, and the inherent absorption of the ultraviolet region originally possessed by the member is distinguished from the provision of the ultraviolet absorption ability. it can.

The method for producing the cellulose ester film according to the present invention will be described. In the production of the cellulose ester film according to the present invention, a dope solution in which the cellulose ester is dissolved in a solvent and a solution in which the ultraviolet absorbing compound and a small amount of the cellulose ester are dissolved are added in-line, mixed, stirred, and then mixed. The liquid is preferably applied and formed into a film.

The dope solution obtained by dissolving the cellulose ester in a solvent is a state in which the cellulose ester is dissolved in a solvent (solvent), and an additive such as a plasticizer may be added to the dope solution. Of course, other additives can be added as needed. The concentration of the cellulose ester in the dope solution is preferably from 10 to 30% by mass, more preferably from 18 to 20% by mass.

The above-mentioned solvents may be used alone or in combination. However, it is preferable to use a mixture of a good solvent and a poor solvent from the viewpoint of productivity efficiency. More preferably, the mixing ratio of the good solvent to the poor solvent is 70%. And the poor solvent is 5 to 30% by mass.

The above-mentioned good solvent and poor solvent are defined as a good solvent that dissolves the cellulose ester used alone and a poor solvent that swells or does not dissolve alone. Therefore, the good solvent and the poor solvent vary depending on the amount of acetic acid bonded to the cellulose ester. For example, when acetone is used as a solvent, a good solvent is obtained when the amount of acetic acid bonded to cellulose ester is 55%, and the poor solvent is used when the amount of acetic acid is 60%. Will be.

Examples of the good solvent include organic halides such as methylene chloride and dioxolanes.
As the poor solvent, for example, methanol, ethanol, n-butanol, cyclohexane and the like are preferably used.

As a method for dissolving the cellulose ester in preparing the above-mentioned dope solution, a general method can be used, but a preferable method is to mix the cellulose ester with a poor solvent and wet or swell. Then, a method of mixing with a good solvent is preferably used.
At this time, a method of heating under pressure, at a temperature not lower than the boiling point of the solvent at normal pressure and within a range in which the solvent does not boil, and dissolving while stirring, prevents the generation of a massive undissolved substance called gel or mamako. Therefore, it is more preferable.

For in-line addition and mixing of a solution in which a small amount of the cellulose ester is dissolved with the dope solution obtained by dissolving the cellulose ester in a solvent and the ultraviolet absorbing compound according to the present invention, for example, Mixers (manufactured by Toray Engineering), in-line mixers such as SWJ (Toray static in-tube mixer, Hi-Mixer) and the like are preferably used. When an in-line mixer is used, it is preferable to concentrate and dissolve under high pressure, and the type of pressurized container is not particularly limited, as long as it can withstand a predetermined pressure and can be heated and stirred under pressure. For the pressurized container, other instruments such as a pressure gauge and a thermometer are appropriately disposed.

Pressurization may be performed by a method of injecting an inert gas such as nitrogen gas or by increasing the vapor pressure of the solvent by heating. Heating is preferably performed from the outside. For example, a jacket type is preferable because temperature control is easy.

The heating temperature after the addition of the solvent is preferably a temperature not lower than the boiling point of the solvent used and not in a range where the solvent does not boil, for example, preferably set in the range of 60 ° C. or higher and 70 to 110 ° C. is there. The pressure is adjusted at the set temperature so that the solvent does not boil.

After the dissolution, it is preferable to take out from the container with cooling, or to take out from the container with a pump or the like, cool it with a heat exchanger or the like, and supply it to a film. The cooling temperature at this time may be cooled to room temperature, but it is more preferable to cool to a temperature 5 to 10 ° C. lower than the boiling point and perform casting at that temperature because the viscosity of the dope solution can be reduced.

A dope solution obtained by dissolving the cellulose ester in a solvent and a solution in which an ultraviolet absorbing compound and a small amount of a cellulose ester are dissolved are added and mixed in-line, and then cast on a support (casting step). Then, after heating to remove a part of the solvent (drying step on the support),
The film is peeled from the support, and the peeled film is dried (film drying step) to obtain a cellulose ester film.

As the support in the casting step, a belt-shaped or drum-shaped support having a mirror-finished stainless steel is preferably used. The temperature of the support in the casting step can be cast at a temperature in a general temperature range of 0 ° C. to a temperature lower than the boiling point of the solvent. It is preferable because the time limit can be increased, and it is more preferable that the film is cast on a support at 5 to 15 ° C. Here, the peeling limit time refers to the time during which the cast dope solution remains on the support in the limit of the casting speed at which a transparent and flat good film can be continuously obtained. A shorter peeling limit time is preferred because of its higher productivity.

The temperature of the support at the time of peeling is 10 to
It is preferable to set the temperature to 40 ° C., more preferably 15 to 30 ° C., because the adhesion between the film and the support can be reduced.

In order for the cellulose ester film to have good flatness at the time of production, the amount of the residual solvent when peeled from the support is preferably from 10 to 80%, more preferably from 20 to 40% or from 60 to 80%. %, Particularly preferably 20 to 30%.

The residual solvent amount is defined by the following equation. Residual solvent amount (%) = (mass before heat treatment−mass after heat treatment) / (mass after heat treatment) × 100 The heat treatment when measuring the amount of residual solvent means that the film is treated at 115 ° C. for 1 hour. Indicates that heat treatment is performed.

The film is usually peeled at a peeling tension of 197.3 to 246.7 N / m when the film is peeled off from the support, but the content of the ultraviolet absorbing compound per unit mass of the cellulose ester is large, and When the film is made thinner, the film is likely to be wrinkled at the time of peeling. Therefore, it is preferable to peel at a peelable minimum tension of 167.7 N / m, more preferably at a peelable minimum tension of 138.1 N / m. That is.

In the drying step of the cellulose ester film, the film separated from the support is further dried to reduce the residual solvent amount to preferably 3% by mass or less, more preferably 0.5% by mass or less. .

The residual solvent amount of the cellulose ester film can be measured by the following method.

<< Method of Measuring Residual Solvent Amount >> A film area of 46.3 cm ² was cut out, finely cut into pieces of about 5 mm, stored in a dedicated vial, sealed with a septum and an aluminum cap, and then sealed with a Hewlett-Packard head. Set it on the space sampler HP7694.

The gas chromatography (GC) connected to the headspace sampler uses a Hewlett-Packard type 5971 equipped with a flame ionization detector (FID) as a detector. The measurement conditions are as follows.

Headspace sampler heating condition: 12
0 ° C., 20 minutes GC introduction temperature 150 ° C. Column: DB-624 manufactured by J & W Increasing temperature: 45 ° C., holding for 3 minutes → 100 ° C. (8 ° C./min) A gas chromatogram is obtained using the above measurement conditions. The solvent to be measured was MEK and methanol, and a fixed amount diluted with butanol was stored in a vial, and the calibration was performed using the peak area of the chromatogram obtained by measuring in the same manner as above. Use the line to get the amount of residual solvent in the film.

In the film drying step, a method of drying the film while transporting the film by a roll hanging method or a pin tenter method is often adopted. For a liquid crystal display member, the film is dried while maintaining the width by a pin tenter method. Is preferable for improving dimensional stability. In particular, it is particularly preferable to maintain the width in a place where the amount of the residual solvent is large immediately after peeling off from the support, in order to further exert the effect of improving the dimensional stability.

The means for drying the film is not particularly limited, and generally, hot air, infrared rays, a heating roll, microwaves or the like can be used. It is preferable to use hot air in terms of simplicity. The drying temperature is preferably divided into three to five stages in a temperature range of 40 to 150 ° C. and gradually increased. To improve the dimensional stability, it is preferable to perform the drying in a temperature range of 80 to 140 ° C. preferable.

The thickness of the cellulose ester film is preferably from 20 to 120 μm, more preferably from 25 to 100 μm, from the viewpoint of the strength as a protective film for a polarizing plate, the dimensional stability of the polarizing plate and the storage stability under wet heat. ,
Particularly preferably, it is 30 to 85 μm. The cellulose ester film according to the present invention preferably contains a plasticizer. Although there is no particular limitation on the plasticizer that can be used, phosphate ester-based triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, etc. For the acid ester type, diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, etc., and for the glycolic acid ester type, triacetin, tributyrin, butyl phthalyl butyl glycolate, ethyl phthalyl ethyl glycol Rate, methylphthalylethyl glycolate and the like can be used alone or in combination.

The proportion of the phosphate ester plasticizer used is as follows:
Since it is difficult to cause hydrolysis of the cellulose ester film and is excellent in durability, it is preferably 50% by mass or less, more preferably 30% by mass or less of the total amount of the plasticizer, and particularly preferably a phthalate ester without using a phosphate ester-based plasticizer. It is preferable to use only plasticizers of the type or glycolate.

The amount of the plasticizer used depends on the film performance,
From the viewpoint of processability, the amount is preferably 1 to 15% by mass relative to the cellulose ester, and from the viewpoint of dimensional stability, the amount is more preferably 1 to 10% by mass, particularly preferably 3 to 10% by mass, for a liquid crystal display member.
７7% by mass.

A matting agent may be added to the cellulose ester film according to the present invention, if necessary. For example, fine particles such as silicon oxide can be added. The fine particles are preferably surface-treated with an organic substance since the haze of the film can be reduced.

Examples of the organic substance used for the surface treatment include halosilanes, alkoxysilanes, silazane, siloxane and the like. The fine particles have an average particle size of primary particles of 5 to 50 m from the viewpoint of mat effect, transparency of the film, and the like.
Is more preferable, and it is more preferable that it is 7-14 m.

[0073]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 <Preparation of Liquid Crystal Cell 1> A 2% by weight solution of PA-1 in methyl ethyl ketone was prepared, spin-coated on a glass substrate with ITO, and then vacuum dried at room temperature to prepare a photo-alignment film.
A polarizer UV polarizing film (HNP'B) was used with a high-pressure mercury lamp, and 4
Irradiation was performed at an angle of 5 ° at 75 mJ / m ² . The two substrates thus fabricated are interposed via spherical spacers such that the gap is 5.2 μm and the directions of the upper and lower substrates irradiated with polarized light are orthogonal to each other. A laminated panel was produced with an adhesive. Nematic liquid crystal was injected into this panel, and the injection port was sealed. As the liquid crystal, a nematic liquid crystal (ZLI4792 manufactured by Merck) mixed with a chiral agent “S-811” (manufactured by Merck) so as to have a pitch length of 70 μm was used.

<Production of Liquid Crystal Cell 2>
The glass substrate with O was spin-coated with a 5% by mass UV-2 chloroform solution on the back side of the surface on which PA-1 was placed, and dried. The dry film thickness was 1.8 μm. Except for this, the liquid crystal cell 2 was produced in the same manner as the liquid crystal cell 1.

[0076]

Embedded image

<Preparation of Support> Preparation of Sample 1 (Preparation of Dope Solution) Cellulose triacetate 100 parts by mass Ethylphthalylethyl glycolate 5 parts by mass Methylene chloride 475 parts by mass Ethanol 50 parts by mass While heating and stirring, the mixture was completely dissolved and filtered to prepare a dope solution. Separately, a solution containing an ultraviolet absorber was prepared as follows.

(Preparation of Solution Containing Ultraviolet Absorber) Ultraviolet absorber (UV-1) 10 parts by mass Cellulose triacetate 4 parts by mass Methylene chloride 100 parts by mass UV-1: 2- (2-hydroxy-3-dodecyl-5) (Methylphenyl) -benzotriazole The above was charged into a closed container, heated, stirred, completely dissolved and filtered to prepare an ultraviolet absorbent-containing solution.

To 100 parts by mass of the dope solution prepared above, an ultraviolet absorber-containing solution was added at a ratio of 4 parts by mass, and an in-line mixer (Toray static tube mixer Hi-Mi) was added.
xer, SWJ). Next, using a belt casting device, a mixed solution of the above-mentioned dope solution and the solution containing an ultraviolet absorber was uniformly cast on a stainless steel band support at a temperature of 33 ° C. and a width of 1500 mm. On the stainless band support, the solvent was evaporated until the residual solvent amount in the cast (cast) triacetylcellulose film became 25%, and then the film was peeled off from the stainless band support at a peeling tension of 130 N / m. The peeled cellulose triacetate film was slit into a width of 1300 mm, and then dried while being conveyed by a number of rolls through a drying zone, slit into a width of 1100 mm, and a film thickness of 80 μm
Of cellulose triacetate film support 1 was obtained.

Preparation of Samples 2 to 8 Supports 2 and 3 were obtained in the same manner except that the kind and amount of the ultraviolet absorbing compound of the support 1 were changed as follows.

Support 1 UV-1 1% by mass Support 2 UV-1 5% by mass Support 3 UV-1 0% by mass (alkaline saponification treatment) Saponification step 2 mol / l NaOH 60 ° C. for 90 seconds Rinse step Water 30 45 ° C. Neutralization step 10% by mass HCl 30 ° C. 45 seconds Rinse step Water 30 ° C. 45 seconds Under the above conditions, the cellulose triacetate film is saponified, washed with water, neutralized, washed with water, and then dried at 80 ° C. Was.

(Preparation of Polarizing Plate) A polyvinyl alcohol film having a thickness of 120 μm was immersed in 100 parts by mass of an aqueous solution containing 1 part by mass of iodine and 4 parts by mass of boric acid and stretched 6 times at 50 ° C. to form a polarizing film. Was. A cellulose triacetate film sample which had been subjected to an alkali saponification treatment on both sides of the polarizing film was bonded to each other using a 5% aqueous solution of completely saponified polyvinyl alcohol as an adhesive to produce a polarizing plate as shown in Table 1 below.

[0083]

[Table 1]

One side of each of the liquid crystal cells 1 and ² was irradiated with a high-pressure mercury lamp (50 J / m ² ) (at 365 nm) at 50 ° C. to perform forced deterioration. A polarizing plate 3 is provided in these liquid crystal cells 1 and 2.
Using an acrylic adhesive such that the transmission axis of the polarizing plate coincides with the direction in which the polarization irradiation axis at the time of photoalignment of the portion near the glass surface to be bonded to the liquid crystal cell is projected on the substrate.
Laminated on both sides of the cell. Before the deterioration test, when the cell was placed on the backlight, white display was displayed at 0 V and black display at 5 V.

After the forced deterioration test, the liquid crystal cell 1 could not display black and white, but the liquid crystal cell 2 had no change in display before and after the deterioration test.

The upper and lower surfaces of the liquid crystal cells 1 and 2 are 18 W
5 fluorescent lamps were arranged at an interval of 15 cm. The liquid crystal cell was placed at a distance of 50 cm from the upper surface and the lower surface and at the position of the third fluorescent lamp among the five fluorescent lamps, and irradiation was performed for 700 hours.

When the polarizing plate was adhered and observed in the same manner as described above, the liquid crystal cell 1 could not perform black and white display after the deterioration test. The display of the liquid crystal cell 2 did not change before and after the deterioration test.

Example 2 As shown in Table 2 below, the structure of the liquid crystal cell and the polarizing plate was changed, for example, by combining the liquid crystal cell and the polarizing plate, and further combining a support. Were fabricated in combination.

(Deterioration Test 1) The liquid crystal cell produced in the configuration shown in Table 2 was forcibly degraded by an xenon long life weather meter at 70,000 lux and 40 ° C. for 500 hours. When the cell was set on the backlight before the deterioration test, white display was obtained when the voltage was 0 V, and black display was obtained when the voltage was 5 V.

Change in black-and-white display before and after the deterioration test ◎ No change ○ Some deterioration but no problem in use × No display (Deterioration test 2) Peel off the polarizing plate on the xenon light irradiated surface of the liquid crystal cell used in Deterioration test 1 It was cut into two pieces. With this in a crossed Nicols state, the polarization behavior was visually observed. The presence of polarization ability can be visually confirmed by the darkened state.

Change in polarization before and after the deterioration test ◎ No change ○ Slightly deteriorated but sufficient polarization ability × Little polarization was lost The results of the above deterioration tests 1 and 2 are also shown in Table 2.

[0092]

[Table 2]

When the member having the ultraviolet absorbing ability is provided outside the photo-alignment film, it is clear that the photo-alignment liquid crystal cell has excellent display resistance. When the member having the ultraviolet absorbing ability is a polarizing plate protective film, the display resistance is remarkably excellent without deterioration of the polarizing plate. Further, by providing a member having an ultraviolet absorbing ability outside the polarizing plate, the resistance of the polarizing plate and the photo-aligned liquid crystal cell is improved.

[0094]

As described above, the display resistance of the photo-aligned liquid crystal cell can be remarkably improved.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Sota Kawakami 1 Sakuracho, Hino-shi, Tokyo Konica Stock Company In-house F-term (reference) 2H049 BA02 BA06 BB13 BB33 BC22 2H090 HB08Y HB09Y LA05 LA06 LA09 LA16 MA01 MA02 MA06 MB01 MB06 MB08 MB14 2H091 FA34X FA34Z FB02 GA06 LA03

Claims (12)

[Claims] A liquid crystal display cell produced by a photo-alignment method, wherein at least one member provided with an ultraviolet absorbing ability comprises a photo-alignment layer closest to the observation side of the liquid crystal display cell and an outermost surface on the observation side. And a liquid crystal display device. 2. A member including a liquid crystal display cell produced by a photo-alignment method and having at least one UV-absorbing ability is provided between the photo-alignment layer closest to the backlight side and the backlight. A liquid crystal display device characterized in that: 3. A liquid crystal display device comprising a liquid crystal display cell produced by a photo-alignment method, wherein at least one member having ultraviolet absorbing ability is provided on each side of the liquid crystal display cell. . 4. The liquid crystal display device according to claim 1, wherein the member having an ultraviolet absorbing ability is in the form of a film. 5. The liquid crystal display device according to claim 4, wherein the resin constituting the film is a cellulose ester. 6. The liquid crystal display device according to claim 1, wherein the ultraviolet absorbing ability is provided by an organic ultraviolet absorbing agent. 7. An optical photo-alignment film protective film comprising an organic ultraviolet absorber. 8. A liquid crystal display cell produced by a photo-alignment method and comprising at least one member provided with an ultraviolet absorbing ability is provided with a photo-alignment layer closest to the observation side of the liquid crystal display and an outermost surface on the observation side. In the liquid crystal display device having at least one between the light alignment layer closest to the backlight side and the backlight, the member provided with the ultraviolet absorbing ability is located on the side farthest from the polarizer closest to the liquid crystal panel. A liquid crystal display device characterized by being installed in a liquid crystal display device. 9. The liquid crystal display device according to claim 8, wherein the member having the ultraviolet absorbing ability is a transparent resin film. 10. The liquid crystal display device according to claim 9, wherein the resin of the transparent resin film is a cellulose ester. 11. The method according to claim 8, wherein the ultraviolet absorbing ability is provided by an organic ultraviolet absorbing agent.
A liquid crystal display device according to the item. 12. The liquid crystal display device according to claim 9, wherein the transparent resin film is a protective film for a polarizing plate.