JP2002207121A - Optical compensation sheet and method for manufacturing liquid crystal display device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical compensation sheet simply improving viewing angle characteristics of a TN type, such as a TN-TFT(twisted nematic-thin film transistor), LCD(liquid crystal display), i.e., coloring of the screen and a phenomenon reversing light and shade recognized in view of oblique direction, and further to provide an LCD device having a remarkably improved viewing angle with simple construction by using the sheet. SOLUTION: The optical compensation sheet, that has at least a layer of an optically anisotropic layer containing liquid crystal molecules which is obtained by fixing orientation of a polymerizable liquid crystalline compound in such a way that an angle between an optic axis of the polymerizable liquid crystalline compound and a supporting body continuously or stepwise decreases with respect to the thickness direction, on the supporting body, is characterized by having >0 and <α/2 average tilt angle θ with respect to the tilt angle αof the liquid crystal molecules existing on the boundary between the alignment layer and the optically anisotropic layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical compensatory sheet and a method for manufacturing a liquid crystal display device using the same.

[0002]

2. Description of the Related Art Conventionally, the following optical compensatory sheets have been used for enlarging the viewing angle of a liquid crystal display device.
Various configurations have been attempted, each proposed as an effective method.

(1) A method of supporting a discotic liquid crystal compound, which is a compound having negative uniaxiality, on a support (2) Depth of a nematic polymer liquid crystal compound having positive optical anisotropy (3) Nematic liquid crystal compound having positive optical anisotropy in a two-layer configuration on a support, in which a hybrid orientation in which the pretilt angle of the liquid crystal molecules changes in the direction is supported. Method of Giving Pseudo-Negative Uniaxial Similar Optical Characteristics by Making Each Layer Orientation Direction at about 90 ° Each of the above-described configurations has the following problems.

In the method described in the above (1), when applied to a TN mode liquid crystal panel, a disadvantage peculiar to a discotic liquid crystal compound that a screen is colored yellow when viewed from an oblique direction appears.

In the method described in (2), the liquid crystal development temperature is high, and the orientation of the liquid crystal cannot be fixed on an isotropic transparent support such as TAC (cellulose triacetate). After the orientation is fixed on the body, it is necessary to transfer to a support such as TAC, which complicates the process and extremely lowers the productivity.

As an example of the method described in the above (3), for example, Japanese Patent Application Laid-Open No. Hei 8-15681 discloses that a rod-shaped optically anisotropic layer using a positive uniaxial low-molecular liquid crystal compound has an alignment ability. Forming a layer of a rod-shaped positive uniaxial low-molecular liquid crystal compound oriented via an orientation layer having
A four-layer optically anisotropic layer in which a layer of a rod-shaped positive uniaxial low-molecular liquid crystal compound which is re-oriented via an orientation layer having an orientation ability again is formed on this layer and fixed. Is disclosed. In this case, by giving the orientation directions projected in the plane of the two liquid crystal layers shifted by, for example, 90 degrees, it becomes possible to give a pseudo disk-like characteristic.

Therefore, the method described in the above (3) has no coloring problem unlike the case of a discotic liquid crystalline compound, and therefore, a liquid crystal TV (television) in which color reproduction is important.
It has a very advantageous feature in such uses.

However, in this method, what was achieved with a single layer of a discotic liquid crystal compound is dared to be achieved with two liquid crystal layers, which is extremely inefficient.

[0009] However, all of these methods have more fundamental and common problems. That is,
According to these systems, each of the liquid crystal panels must be arranged on both sides in order to obtain optical compensation capability. This means that the method of improving the viewing angle using the optical compensation film, which is considered to be simple, is very expensive. In these systems, when only one image is used, the left-right symmetry is always lost, and the viewing angle characteristic becomes asymmetric. In addition, even if the rubbing axis is rotated by 45 degrees and displaced, for example, when the arrangement is performed, the symmetry may be improved, but the viewing angle characteristics are not improved. As described above, there has not yet been a method for improving the viewing angle characteristics by using one optical compensation sheet to be equal to or more than two optical compensation sheets.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a TN
-Viewing angle characteristics of a TN type LCD such as a TFT,
Provided is an optical compensatory sheet which can easily improve the coloring of a screen and the reversal of light and dark when viewed from an oblique direction, and a liquid crystal display device in which the viewing angle is remarkably improved with a simple structure using the same. That is.

[0011]

The above objects of the present invention have been attained by the following items 1 to 15.

1. A coating liquid containing a polymerizable liquid crystal compound is applied to the side of the support A having the alignment layer on the side having the alignment layer, or the support is coated on a support having an alignment property (referred to as support B). The angle between the optical axis of the polymerizable liquid crystal compound applied and the surface of the support (including both supports A and B, simply referred to as a support) is determined by applying the coating solution. An optically anisotropic compound obtained by fixing the orientation of the polymerizable liquid crystalline compound so as to decrease continuously or stepwise in the thickness direction of the layer provided by the coating liquid from In the optical compensation sheet in which all of the optically anisotropic layers are adjusted to include, the tilt angle α of the optically anisotropic compound present at the interface between the alignment layer or the support B and the optically anisotropic layer. The average tilt angle θ is 0 <θ <α / 2.

2. A coating liquid containing a polymerizable liquid crystal compound is applied to the side of the support A having the alignment layer on the side having the alignment layer, or the support is coated on a support having an alignment property (referred to as support B). The angle between the optical axis of the polymerizable liquid crystal compound applied and the surface of the support (including both supports A and B, simply referred to as a support) is determined by applying the coating solution. An optically anisotropic compound obtained by fixing the orientation of the polymerizable liquid crystal compound so as to increase continuously or stepwise in the thickness direction of the layer provided by the coating solution from In the optical compensation sheet in which all of the optically anisotropic layers are adjusted so as to include the optically anisotropic layer, the average tilt angle θ is 0 <θ with respect to the tilt angle β of the optically anisotropic compound present at the interface between the optically anisotropic layer and the air.
<Β / 2.

3. A coating liquid containing a polymerizable liquid crystal compound is applied to the side of the support A having the alignment layer on the side having the alignment layer, or the support is coated on a support having an alignment property (referred to as support B). The angle between the optical axis of the polymerizable liquid crystal compound applied and the surface of the support (including both supports A and B, simply referred to as a support) is determined by applying the coating solution. An optically anisotropic compound obtained by fixing the orientation of the polymerizable liquid crystalline compound so as to decrease continuously or stepwise in the thickness direction of the layer provided by the coating liquid from In an optical compensatory sheet in which all of the optically anisotropic layer is adjusted so as to include the optically anisotropic compound having an orientation fixed in the optically anisotropic layer (the optical axis of the compound) and the surface of the optically compensatory sheet. The optically anisotropic compound is contained in an angle range of 40 ° to 50 ° at least 5%. Optical compensation sheet.

4. A coating liquid containing a polymerizable liquid crystal compound is applied to the side of the support A having the alignment layer on the side having the alignment layer, or the support is coated on a support having an alignment property (referred to as support B). The angle between the optical axis of the polymerizable liquid crystal compound applied and the surface of the support (including both supports A and B, simply referred to as a support) is determined by applying the coating solution. An optically anisotropic compound obtained by fixing the orientation of the polymerizable liquid crystal compound so as to increase continuously or stepwise in the thickness direction of the layer provided by the coating solution from In the optical compensation sheet in which all of the optically anisotropic layers are adjusted to include, the angle between the optical axis of the optically anisotropic compound whose orientation is fixed in the optically anisotropic layer and the surface of the optically compensatory sheet. 4
An optical compensatory sheet comprising at least 5% of the optically anisotropic compound in a range of 0 ° to 50 °.

5. Supports (including both supports A and B,
(Hereinafter simply referred to as a support) having at least two optically anisotropic layers on one or both sides, and the optical slow axes of the optically anisotropic layers in the plane of the optical compensation sheet intersecting at 80 ° to 100 °. 4. The optical compensation sheet according to the above item 1 or 3, wherein:

6. Supports (including both supports A and B,
(Hereinafter simply referred to as a support) having at least two optically anisotropic layers on one or both sides, and the optical slow axes of the optically anisotropic layers in the plane of the optical compensation sheet intersecting at 80 ° to 100 °. 5. The optical compensation sheet according to the above 2 or 4, wherein

[7] Supports (including both supports A and B,
The optically anisotropic layer has at least one layer on each of one side and both sides of the optically anisotropic layer, and the optical slow axes of the optically anisotropic layer in the plane of the optical compensation sheet intersect at 80 ° to 100 °. 5. The optical compensatory sheet according to the above item 3 or 4, wherein

8. Supports (including both supports A and B,
Characterized in that an optically biaxial cellulose ester film is used as the support).
The optical compensation sheet according to any one of the above.

9. Supports (including both supports A and B,
An optically biaxial cellulose ester film is used as the support), the direction in which the refractive index of the support in the optical compensation sheet surface is maximized, and the refraction of the optically anisotropic layer in the optical compensation sheet surface. The direction in which the rate is maximum is 80 ° to 100
The optical compensatory sheet according to any one of the above items 1 to 7, which intersects at an angle of °.

10. An optically biaxial cellulose ester film is used as a support (including both supports A and B, simply referred to as a support), and the direction in which the refractive index of the support in the plane of the optical compensation sheet is maximized. The direction in which the refractive index of the at least one optically anisotropic layer in the plane of the optical compensatory sheet is maximized intersects at 80 ° to 100 °. Optical compensation sheet.

11. The optical compensatory sheet according to any one of the above items 1 to 10, wherein a rod-shaped liquid crystal compound is used as the polymerizable liquid crystal compound.

12. The support (including both supports A and B, simply referred to as a support) is an optically biaxial cellulose ester film, and the support has an in-plane retardation value (R ₀ ) of 5 to 5. in a range of 95 nm, a thickness direction retardation value (R _t) is 15 to 3
1-11.
The optical compensation sheet according to any one of the above.

13. Any one of the above items 1 to 12, comprising at least one alignment layer and at least one elution block layer between the support and the optically anisotropic layer.
An optical compensation sheet according to the item.

14. 14. The optical compensatory sheet as described in 13 above, wherein the elution block layer contains a water-soluble polymer.

15. In manufacturing liquid crystal display devices,
15. A method for manufacturing a liquid crystal display device, comprising: manufacturing the optical compensation sheet according to any one of the above items 1 to 14 on only one side of the liquid crystal display.

Hereinafter, the present invention will be described in detail. In conventional optical compensatory sheets, practically available optical compensatory ability was obtained only by disposing them on both sides of a liquid crystal cell. However, the present inventors have surprisingly produced only one sheet between the liquid crystal cell and the polarizing plate on one side only by producing an optical compensation sheet having the optically anisotropic layer having the above-described configuration. It has been found that an extremely excellent optical compensation ability can be obtained only by disposing.

The optical compensatory sheet of the present invention has a high contrast when viewed from an oblique direction, not only a wide viewing angle, but also no coloring of the screen when viewed from an oblique direction, and a very small inversion area. It showed excellent optical compensation ability. Since only one optical compensatory sheet of the present invention is used for one liquid crystal cell, the cost is halved.
It is possible to supply the liquid crystal cell to twice the amount of the liquid crystal cell.

Also, the surface of the polarizing plate is usually different between the front side (observer side) and the back side of the liquid crystal cell. For example, a special polarizing plate treated with AG (anti-glare) is used on the front side. Used. In this case, since the polarizing plate on the front side and the polarizing plate on the back side are of different types, it is inevitable to prepare a laminated optical compensatory sheet for each,
Furthermore, if an abnormality occurs during the bonding process with the surface-processed polarizing plate, the surface-processed polarizing plate must be discarded, resulting in an increase in cost. However, according to the present invention, a polarizing plate having such an additional function is not wasted by bonding the polarizing plate to a polarizing plate on which no special surface processing is performed. Further, the use of the optical compensatory sheet of the present invention reduces the number of triacetyl celluloses used in the optical compensatory sheet and the yellowish coloring caused by the wavelength dispersion characteristics of the discotic liquid crystalline compound, for example, so that the number of sheets can be reduced by one. Becomes possible.

The present invention has made it possible to provide an optical compensatory sheet which can be compensated for by only one sheet, a polarizing plate and a liquid crystal display device using the optical compensatory sheet, and more specifically, twisted nematic (TN). Of the contrast due to the viewing angle peculiar to the liquid crystal of the liquid crystal display, and in particular, the viewing angle dependence of the display of an active matrix TN type liquid crystal display device used as a full color display.

The orientation of the liquid crystalline compound according to the present invention in the liquid crystal layer will be described. As the optical compensatory sheet of the present invention, a layer in which a birefringent material is oriented has two layers.
It is also preferably used in the case of lamination of layers or more. The feature is that the orientation directions of these two layers are substantially orthogonal to each other in the plane. Here, substantially orthogonal may have a certain width from 90 degrees within a range in which coloring due to interference is not a problem, but is preferably substantially 80 to 100 degrees.
It is more preferably in the range of 85 to 95 degrees, and most preferably 90 degrees. Further, in the constituent unit of the birefringent material, the direction showing the maximum value of the refractive index in the refractive index ellipsoid is such that the angle between the first layer and the sheet surface is one surface of the sheet (A surface). To the other surface (Surface B) in the thickness direction of the sheet, and the angle between the second layer and the sheet surface is similarly increased from the surface A to the surface B. Characterized in that they are arranged so as to decrease in the vertical direction.

The constitutional unit of the birefringent material mentioned here can be understood as a unit having an optical axis, for example, a molecule of a liquid crystal compound having birefringence.
It is not necessarily limited to a molecular unit, and when an aggregate of a plurality of molecules has a certain optical axis, it can also refer to the aggregate. Further, an increase or decrease in the angle with the sheet surface means that each of the layers does not have an optical axis as a whole layer, and the increase or decrease in the angle is in the thickness direction of the sheet. May change continuously or intermittently. Such an orientation in the thickness direction of the sheet may be hereinafter referred to as hybrid orientation. The form of the hybrid orientation in the thickness direction that is effective for the present invention will be described in the case of two-layer lamination.
From the surface side to the surface B side, the angle between the sheet surface and the sheet surface preferably increases in the first layer and decreases in the second layer, or preferably decreases in the first layer and increases in the second layer. The effect of the present invention does not occur when the angle increases or decreases, or when the angle is constant. The angle formed by the sheet surface can vary between 0 degree and 90 degrees. Preferably, it is 5 degrees to 85 degrees, and it is generally preferable that the range of change of the angle is wide. However, this is also changed depending on the design of the liquid crystal cell. The shape of the change in the angle (hybrid form) is preferably the same when the cross section of the sheet is viewed in the first layer and the second layer.

A coating liquid containing a liquid crystal compound is applied, and preferably used to realize the optically anisotropic layer as described above by controlling the orientation of the applied liquid crystal compound. Can be done. In the present invention, a polymerizable liquid crystal compound is used as the liquid crystal compound. Hereinafter, the polymerizable liquid crystal compound according to the present invention will be described.

The polymerizable liquid crystal compound according to the present invention may be a low molecular weight polymerizable liquid crystal compound or a polymerizable liquid crystal compound. As the optical characteristics of the polymerizable liquid crystal compound, a positive uniaxial rod-shaped polymerizable liquid crystal compound and a biaxial polymerizable liquid crystal compound are preferably used. Further, the compound may exhibit negative uniaxiality. For example, typically, a discotic liquid crystalline compound having polymerizability can be used. The biaxial polymerizable liquid crystal compound can have a rod-like molecular form,
There are discotic compounds, such as discotic compounds, that have a shape that resembles a disk with a certain extent.

The polymerizable liquid crystal compound having a negative uniaxial property according to the present invention is typically a discotic liquid crystal compound. For example, liquid crystal chemistry: quarterly;
o. 22, 1994, edited by The Chemical Society of Japan (Society Publishing Center), pp. 60-72. Specifically, it has a molecular structure 1-46 as described on p. Liquid crystal compound having Also, Patent Publication Nos. 2587398, 2640083, 26441086, 2692033, and 269
No. 2035, No. 2767382, No. 274778
Compounds obtained by imparting polymerizability to liquid crystal compounds such as those described in No. 9 and the like are also included in the category of polymerizable discotic liquid crystal compounds.

Here, a polymerizable liquid crystal compound having a positive uniaxial optical anisotropy (also simply referred to as having a positive uniaxial property) or a polymerizable liquid crystal compound exhibiting optical characteristics close to those of a rod-shaped liquid crystal compound. The axial polymerizable liquid crystal compound can be treated as optical characteristics of the rod-shaped liquid crystal compound. Here, having a positive uniaxial property (optically uniaxial) means that the refractive index values nx and n in the triaxial directions in an anisotropic element having optical anisotropy.
Only two of y and nz have the same value, and the two refractive indices are smaller than the refractive index of the remaining one axis. nx,
ny and nz each represent a different value.

More specifically, the positive uniaxial rod-like polymerizable liquid crystal compound according to the present invention may have a positive or negative dielectric anisotropy. From the viewpoint of easy inclination control in the thickness direction, a material having a positive dielectric anisotropy is preferable.

The dielectric anisotropy (Δε) of a rod-shaped polymerizable liquid crystalline compound is defined as the dielectric constant (ε //) in which the major axis of the molecule is oriented parallel to the electrolysis and the minor axis of the molecule indicates the electrolysis. The difference between the value of the dielectric constant (ε⊥) and the value of Δε (= ε // −)
ε⊥ ≠ 0). The dielectric anisotropy (Δε) affects the anisotropy of the refractive index of the light passing through the liquid crystal molecules, and the relationship between the two is Δε = n / −2⊥2 (where Δn =
n // − n⊥ = ne−no; ne is an extraordinary refractive index, no
Is the ordinary light refractive index, n // is the refractive index for light that is biased in the direction of the orientation vector of the liquid crystal molecules, and n⊥ is the refractive index for light that is biased in the direction perpendicular to the orientation vector.

The values of Δε and Δn are positive values in the case of a liquid crystal compound used for driving a normal TN liquid crystal cell or the like.

The optical anisotropy (specifically, the anisotropy of the refractive index) of the polymerizable liquid crystal compound is defined by the whole molecule in the case of a low molecular weight polymerizable liquid crystal compound, and has polymerizability. In the case of a high-molecular liquid crystal compound, there are roughly classified a main-chain liquid crystal and a side-chain liquid crystal. In each case, the mesogen group is defined according to the low-molecular liquid crystal compound.

The mesogen group (mesogen unit) described above represents a portion essential for imparting liquid crystallinity in a liquid crystal compound. Usually, a mesogen group (mesogen unit) is a rigid core or a flexible portion. , And a terminal group located at the terminal, but it is not always necessary to have all of the above three parts as long as the structure allows the liquid crystal compound to exhibit a liquid crystal phase.

Specific examples of the positive uniaxial rod-shaped polymerizable liquid crystal compound include liquid crystal chemistry: Quarterly Chemical Review No. 22,
1994, The Chemical Society of Japan (Society Publishing Center), 42,
The compound can be synthesized with reference to the compounds listed on page 44. Further, a compound or the like obtained by imparting polymerizability to a normal rod-like nematic liquid crystal used for a TN cell can also be suitably used. Further, as the rod-shaped polymerized liquid crystalline compound according to the present invention, those exhibiting a nematic liquid crystal phase are preferably used.

The biaxial polymerizable liquid crystal compound is, for example,
Synthetic Organic Chemistry, Vol. 49; No. 5 (1991), 124
Compounds described on pages 143 to 143; W. Bruce et al. [AN EU-SPONSORED 'OXFOR
D WORKSHOP ONBIAXIAL NEMA
TICS '(St Benet's Hall, Uni)
version of Oxford 20-22 D
esmber, 1996), p157-293],
S. CHANDRASEKHAR and other research reports [AT
hermetic Biaxial Nemat
ic Liquid Crystal; Mol. Cry
st. Liq. Cryst. 1988, Vol. 16
5, pp. 123-130]; Demus, J .; G
Goodby et al. [Handbook of Liqui
d Crystals Vol. 2B: Low Mol
ecological Weight Liquid Crys
tals II, pp933-943: WILEY-VC
H company] can be synthesized by imparting polymerizability (for example, by substituting an acryl group, a methacryl group, a vinyl group, etc.) to the compounds described in the above.

The liquid crystalline polymer used in the present invention is not particularly limited, but preferably has a positive or negative intrinsic birefringence value. See “LI
QUID CRYSTALS, 1989, Vol. 5,
NO. 1, pp. 159-170 ".

The liquid crystalline polymer used in the present invention is roughly classified into a main chain type and a side chain type as described above, in which the mesogen group is incorporated. It can also be classified into thermotropic and lyotropic.

The liquid crystalline polymer used in the present invention is not particularly limited, but it is preferable to form a nematic liquid crystal. Further, a side chain type is preferred in terms of orientation, and a thermotropic is preferred in terms of orientation fixation. The skeleton used in the side chain type liquid crystalline polymer is preferably a vinyl type polymer, polysiloxane, polypeptide, polyphosphazene, polyethyleneimine, cellulose or the like.

The alignment layer according to the present invention will be described. The alignment layer and / or the support having alignment properties according to the present invention are used to fix the alignment of the liquid crystal compound in the optically anisotropic layer adjacent to the optically anisotropic layer described below.

Here, the material constituting the alignment layer will be described. Specific examples include the following resins and substrates, but are not limited thereto. For example, polyimide, polyamide imide, polyamide, polyether imide, polyether ether ketone, polyether ketone, polyketone sulfide, polyether sulfone, polysulfone, polyphenylene sulfide, polyphenylene oxide, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyacetal , Polycarbonate, polyarylate, acrylic resin, polyvinyl alcohol, polypropylene, cellulosic plastics, epoxy resin, phenol resin and the like.

The alignment layer can be obtained by applying the above-mentioned alignment layer on the transparent resin substrate of the present invention, drying and setting the layer, and then performing a rubbing treatment. Also, Japanese Patent Application Laid-Open No. 9-2
It is also possible to subject the support described in JP-A-81331 and the transparent resin itself to an orientation treatment.

In the present invention, a poval film, which is widely used as an alignment layer for aligning a liquid crystal compound, can be preferably used as an alignment film. The poval is completely saponified (for example, Kuraray Povar PVA-10).
5) and alkyl-modified modified poval (for example, Kuraray Poval MP-203) and the like, but modified poval is more preferably used to control the tilt angle of liquid crystal molecules.

For the rubbing treatment, a treatment method widely used as a liquid crystal alignment treatment step of an LCD can be used. That is, a method of rubbing the surface of the alignment film in a certain direction using paper, gauze, felt, rubber, nylon, polyester fiber or the like to obtain the alignment can be used. In general, rubbing is performed by using a cloth in which fibers having a uniform length and thickness are planted on average.

The optically anisotropic layer according to the present invention will be described. The optically anisotropic layer according to the present invention, after applying a coating liquid containing the above-described polymerizable liquid crystalline compound, a support having alignment ability, or the polymerizable liquid crystal compound is aligned by an alignment layer on the support. This is a layer containing an optically anisotropic compound obtained by performing a polymerization reaction by light or heat simultaneously with or after alignment to fix the alignment.

Next, the fixation of the orientation of the polymerizable liquid crystalline compound according to the present invention will be described. In order to make the optically anisotropic layer (also referred to as an optical compensation layer) of the optical compensation sheet of the present invention more stable, a polymerizable liquid crystal compound is oriented, and then a polymerization reaction is carried out using light or heat. It is preferable to stabilize immobilization. The polymerizable liquid crystal compound according to the present invention can fix the orientation by performing a cross-linking reaction between the polymer matrix and the polymerizable low-molecular liquid crystal compound in addition to performing the polymerization reaction between the polymerizable low-molecular liquid crystals. May be done.

As a method for fixing the alignment state of the polymerizable liquid crystal compound according to the present invention, all methods generally known can be employed. For example, the polymerizable liquid crystal compound according to the present invention (including a low molecular weight polymerizable liquid crystal compound and a polymerizable polymer liquid crystal compound) may be mixed with a liquid crystal phase exhibiting temperature (for example, from room temperature to 100 ° C.). The liquid crystal layer is formed while maintaining the range of (according to the type), and at the same time as or before aligning the liquid crystal layer on the substrate, a photopolymerization initiator or a thermal polymerization initiator is added in advance to perform polymerization (light, (Including the case of heat) to fix the orientation of liquid crystal molecules.

Alternatively, a solution prepared by dissolving the polymerizable liquid crystal compound and the polymerization initiator (including both light and heat) according to the present invention in a solvent is applied on the alignment layer, dried, and then formed into a nematic phase. The alignment state (nematic phase) can be fixed by heating to a temperature, polymerization (by heat, irradiation with UV light, or the like), and then cooling.

As another method for fixing the orientation, a reactive substituent such as a substituent having active hydrogen is provided at the terminal of the polymerizable liquid crystal compound molecule, and the terminal is provided with the reactive substituent. A method in which a polymerizable liquid crystal compound and a polymer matrix are reacted by heat, light or a change in pH to fix the alignment, and the polymerizable liquid crystal compounds having a reactive substituent are cross-linked in individual liquid crystal domains. Accordingly, a method of fixing the orientation may be used in combination, and the present invention is not limited to the above-described method, and various conventionally known fixing techniques can be applied.

Examples of the above-mentioned thermal polymerization initiator include azo compounds, organic peroxides, inorganic peroxides and sulfinic acids. Examples of the photopolymerization initiator include benzophenones and acetophenone. , Benzoins, thioxanthones and the like.

The layer structure according to the optical compensation sheet of the present invention will be described. The layer structure according to the present invention has at least one layer that satisfies the above-described orientation mode on the support.In the present invention, a layer that satisfies the above-described orientation mode is provided on one or both sides of the support. It is preferable to have at least two layers.

As a typical example in the case of having at least two layers satisfying the above-mentioned orientation mode, for example, the following configuration can be mentioned. For the purpose of explanation, the optically anisotropic layer, which is a layer having birefringence, shall be composed of an oriented optically positive uniaxial rod-like liquid crystal compound, and the direction of the optical axis of the molecule will be the sheet surface. When explaining the change in angle, A
Considering in a certain direction from the surface to the surface B, “increase” and “decrease” are described as “increase” and “decrease”, respectively.
In this case, from one side (A side) of the sheet, (1) support-layer "increase"-layer "increase" (2) support-layer "decrease"-layer "decrease" (3) ) "Increase"layer-support-"increase" layer (4) "decrease"layer-support-"decrease" layer (5) support-"decrease"layer-"decrease" layer- Support (6) Support-"increase"layer-"increase" layer-support, etc. are conceivable.

The "increase" layer and the "decrease" layer are respectively
There may be a single layer or multiple layers, but it is necessary that the "increase" layer is always used in combination with the "increase" layer, and the "decrease" layer is always used in combination with the "decrease" layer. On the other hand, a layer that increases and a layer that decreases is not used in combination on one optical compensation film.

The above-mentioned (1) and (2) show that a liquid crystal compound is oriented on a support through an orientation film which gives a normal pretilt angle (more than 0 degree and not more than 40 degrees). This is achieved by transferring a layer in which a second liquid crystal compound is similarly formed on another support and is oriented, for example, via an adhesive. Further, the above (5) and (6)
Is a case where the whole of the support is transferred by this method.

For example, the method of transferring the whole support is as follows.
The optical compensatory sheet of the present invention can be produced more easily. That is, it can be produced by forming one optically anisotropic layer on the support, folding the optically anisotropic layer in two around a 45 ° axis with respect to the orientation direction in the sheet plane, and laminating. .

The above (1) can be achieved by another method. For example, a liquid crystal compound is aligned on a layer on which a liquid crystal compound is aligned via the above-described alignment film that gives a normal pretilt angle on a support, and then on an alignment film that provides homeotropic alignment. This is achieved by:

The above (2) is also achieved by reversing the layer in which the first liquid crystal compound is oriented and the second layer in the same manner.

In the above (3) and (4), a layer in which a liquid crystalline compound is oriented on both sides of a support via an orientation film having the same properties is formed, and each of them provides homeotropic orientation. This is a case in which alignment films and alignment films giving a normal pretilt angle are used. This is typically achieved by coating and orienting a liquid crystalline compound on both sides of the support, for example, as another method, after forming one optically anisotropic layer on the support. Alternatively, it can be manufactured by folding and laminating the support with the support inward about a 45-degree axis with respect to the orientation direction in the sheet plane. Regardless of the layer configuration, the angle of the orientation direction of each layer in the plane is approximately 90 degrees.

An arrangement method when the optical compensatory sheet of the present invention is used after being bonded to a liquid crystal cell will be described.

The arrangement direction is preferably set in accordance with the alignment direction of at least one optically anisotropic layer with respect to the transmission axis of the polarizing plate (also referred to as being substantially parallel). The deviation between the orientation direction of the optically anisotropic layer and the transmission axis of the polarizing plate does not have a large effect as long as it is a little, but in order to maintain the effect described in the present invention, the deviation should be suppressed to about ± 5 degrees. Is preferred.

The relationship between the arrangement of the optical compensatory sheet and the liquid crystal cell is such that when the rubbing direction on the front side (observer side) of the liquid crystal cell is a 45-degree tilt direction from the upper right to the lower left of the panel, the front side of the liquid crystal cell. The tilt angle of the optically anisotropic compound of the optical compensation sheet arranged on the side, in order from the front of the sheet surface,
The angle between the first layer and the sheet surface decreases from upper right to lower left in the plane, and the angle between the second layer and the sheet surface increases from upper left to lower right in the plane. The following arrangement methods can be given as an example, but the present invention is not limited to these arrangements.

Next, the adhesive layer that can be disposed between the optically anisotropic layer and the support according to the present invention will be described.

In the configuration of the optical compensation sheet of the present invention, it is preferable to provide an adhesive layer in order to improve the adhesiveness between the polarizer (liquid crystal layer) and the support. In the configuration of the optical compensation sheet of the present invention, an ultraviolet-cured coating layer is preferably provided on one side of the support, and an adhesive layer for improving the adhesiveness with the polarizing film (liquid crystal layer) is provided on the other side. Provided.

The adhesive layer may be a single layer or two or more layers, and a hydrophilic polymer compound is preferably used to make the adhesive layer easy to adhere. Examples of the hydrophilic polymer compound include a -COOH group-containing polymer compound, preferably a -COOH group-containing vinyl acetate-maleic acid copolymer, or a hydrophilic cellulose derivative, a polyvinyl alcohol derivative, a natural polymer compound, and a hydrophilic polymer. Examples include a polyester derivative and a polyvinyl derivative.

The support according to the optical compensation sheet of the present invention will be described. The support according to the present invention is preferably a transparent support, more preferably a transparent support having a light transmittance of 80% or more.

In the support according to the present invention, the support itself is provided with the function as the above-mentioned alignment layer, that is, the ability to align the polymerizable liquid crystal compound coated on the support. A support may be used.

The support provided with the ability to align the polymerizable liquid crystal compound as described above is described in, for example, JP-A-9-2.
The support described in No. 81331 can be used.

As such a material, a material formed of a material having a small intrinsic birefringence value such as triacetyl cellulose is preferable, and a triacetyl cellulose film (manufactured by Konica Corporation) can be used.

However, as long as the light transmittance is good, it is preferable that a material having a large intrinsic refractive index has optical isotropy when the film is formed, especially when viewed from the front. Such materials include ZEONEX (manufactured by ZEON CORPORATION), ARTO
A commercially available product such as N (manufactured by Nippon Synthetic Rubber Co., Ltd.) can be used. Furthermore, even for materials having a large intrinsic birefringence, such as polycarbonate, polyarylate, polysulfone, and polyethersulfone, conditions such as solution casting and melt extrusion, and stretching conditions in the longitudinal and transverse directions are appropriately set. Can be obtained.

The support according to the present invention is not particularly limited as long as it is a transparent material. However, as long as it is optically substantially isotropic, the optical anisotropy of the entire sheet is determined by the liquid crystal layer. It is preferable because it is easy to control.

The TN type liquid crystal cell exhibits a positive uniaxial property because the liquid crystal molecules in the middle of the liquid crystal layer are vertically aligned at the time of black display. It has a negative uniaxial property having an optical axis in the linear direction, or has a biaxial property in which the in-plane refractive index anisotropy is different, and the refractive index in the normal direction of the support surface is a smaller value. (Nx ≠ ny> nz, where nx; one direction in the plane of the support, ny; a direction orthogonal to nx in the plane of the support, nz; the thickness direction of the support). Acetyl cellulose propionate is an example of a material that easily obtains such characteristics. Preferably, the acetyl substitution degree is 2.0 and the propionyl substitution degree is 0.8.

[0079]

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

Example 1 << Preparation of transparent supports 1 and 2 >> Dope composition 1 described below
Was used to produce transparent supports 1 and 2.

(Preparation of Dope Composition 1) Cellulose triacetate synthesized from cotton linter (degree of acetylation: 61.0%) 50 parts Cellulose triacetate synthesized from wood pulp (degree of acetylation: 61.0%) 50 parts Tinuvin 326 (Ciba Specialty Chemicals) 0.5 parts Tinuvin 328 (Ciba Specialty Chemicals) 0.5 parts Triphenyl phosphate (plasticizer A) 12 parts Aerosil 200 (fine particle silica, Nippon Aerosil Co., 0.016 μm) 0 .1 part Methylene chloride 460 parts Ethanol 40 parts The above-mentioned dope composition 1 was charged into a closed container, and 8 parts were placed under pressure.
The mixture was completely dissolved while keeping the temperature at 0 ° C and stirring. Next, the dope was filtered, cooled and kept at 31 ° C., and was uniformly cast on a rotating endless stainless steel band having a length of 6 m (effective length 5.5 m) stretched between two drums. At the point when the solvent was evaporated until the solvent amount became 50%, the solvent was peeled off from the stainless steel band at a peeling tension of 9.8 N / m, and dried while being transported by a number of rolls at a transporting tension of 127 N / m. A transparent support 1 (cellulose triacetate (TAC) film) was obtained. Further, a transparent support 2 was produced in the same manner except that the film thickness was adjusted to 40 μm.

<< Preparation of Transparent Support 3 >> Cellulose resin (cellulose acetate having a degree of acetyl group substitution of 2.92 (number average molecular weight: 200,000) and acetyl group substitution degree of 2.92.
45 cellulose acetate (number average molecular weight 10,000
0), and the average degree of acetyl group substitution after mixing is 2.6.
5 parts by mass), 5 parts by mass of ethylphthalylethyl glycolate, 3 parts by mass of triphenyl phosphate, 290 parts by mass of methylene chloride, ethanol 6
0 parts by mass was put in a closed container, and the mixture was gradually heated while slowly stirring, and raised to 45 ° C. over 60 minutes to dissolve. The pressure in the container was 1.2 atm.

This dope was prepared using Azumi Filter Paper No. manufactured by Azumi Filter Paper Co., Ltd. After filtration using 244, the mixture was allowed to stand for 24 hours to remove bubbles in the dope. Separately, 5 parts by mass of cellulose acetate propionate and Tinuvin 326 were used.
6 parts by mass (manufactured by Ciba Specialty Chemicals), 4 parts by mass of Tinuvin 109 (manufactured by Ciba Specialty Chemicals), Tinuvin 171 (manufactured by Ciba Specialty Chemicals) and AEROSIL
One part by mass of R972V (manufactured by Nippon Aerosil Co., Ltd.) was mixed with 94 parts by mass of methylene chloride and 8 parts by mass of ethanol and dissolved by stirring to prepare an ultraviolet absorbent solution. 2 parts of the ultraviolet absorbent solution was added to 100 parts by weight of the dope.
After mixing with a static mixer, a dope temperature of 3 was added from a die onto a stainless steel belt.
It was cast at 0 ° C. After drying for 1 minute on a temperature-controlled stainless steel belt by contacting warm water at a temperature of 25 ° C. from the back surface of the stainless steel belt, further contacting 15 ° C. cold water on the back surface of the stainless steel belt and holding for 15 seconds, Peeled from stainless steel belt. The residual solvent amount in the web at the time of peeling was 100% by mass.

Then, both ends of the peeled web were gripped with clips using a simultaneous biaxial stretching tenter, and the intervals between the clips were simultaneously changed in the width direction and the casting direction (length direction). The film was stretched 1.05 times and 1.2 times in the casting direction (length direction). After the stretching was completed, the film temperature was once cooled to 80 ° C., and then stretched 1.05 times in the length direction at 130 ° C. using rollers having different peripheral speeds. Further, the film was dried at 130 ° C. for 10 minutes while being transported by a roller to obtain a cellulose ester film having a thickness of 100 μm.

This cellulose ester film is a glass fiber reinforced resin core having a core diameter of 200 mm and a width of 1 m.
The film was wound into a film roll having a length of 1000 m by a taper tension method. At this time, a temperature of 250
The embossing ring of ° C. was pressed, and the thickness was processed to prevent adhesion between the films.

<< Retardation of Support (R ₀ (n
m), R _t (nm), R _t / R ₀ ) Measurement >> For each of the transparent supports 1 to 3 obtained above, an automatic birefringence meter KOB
Using RA-21ADH (manufactured by Oji Scientific Instruments),
The angle characteristic of the retardation at a wavelength of 590 nm was measured in an environment of 23 ° C. and 55% RH.

The physical properties of the transparent supports 1, 2, and 3 are shown below. Thickness R ₀ R _t Transparent support 1 80 μm 2.0 nm 52.2 nm Transparent support 2 40 μm 2.0 nm 31.0 nm Transparent support 3 100 μm 65.0 nm 72.1 nm Here, R ₀ and R _t are the following formulas. 5 shows the retardation values of the transparent support defined in (a) and (b).

(A) R ₀ = (nx−ny) × d (b) R _t = ((nx + ny) / 2−nz) × d where nx is the maximum refractive index direction in the plane of the support. Some x
The direction, ny, is the refractive index in the y direction, which is the direction in the plane of the support perpendicular to the x direction. nz is the refractive index of the support in the thickness direction, and d is the thickness (nm) of the support.

<< Preparation of Alignment Film (also referred to as Alignment Layer) >> By the following method, an alignment film was applied on the above-prepared transparent support to prepare various alignment films.
In addition, when preparing the alignment film, 0.1
A gelatin subbing layer having a thickness of μm was provided.

(Preparation of Alignment Film A-1) Transparent Support 1
1 g of a linear alkyl-modified polyvinyl alcohol (MP-203; manufactured by Kuraray Co., Ltd.) was placed on a gelatin subbing layer of 100 m in a solvent having a mixing ratio of methanol: water = 1: 4.
After dissolving in l, the mixture was applied with a wire bar # 3. Then
After drying with hot air at 80 ° C., a rubbing treatment was performed to prepare an alignment film A-1.

(Preparation of Alignment Film A-2) Transparent Support 1
1 g of an alkyl-modified polyvinyl alcohol having the following structure was dissolved in 100 ml of a solvent having a mixing ratio of methanol: water = 1: 4, and then applied by a wire bar # 3. This was dried with warm air at 80 ° C. and then subjected to a rubbing treatment to prepare an alignment film A-2.

[0092]

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(Preparation of Alignment Film A-3) An alignment film A-3 was prepared in the same manner except that the transparent support 1 of the alignment film A-1 was changed to the transparent support 3. The rubbing direction was set so as to be substantially perpendicular to the direction in which the in-plane refractive index of the transparent support became maximum.

(Preparation of Alignment Film A-4) An alignment film A-4 was prepared in the same manner except that the transparent support 1 of the alignment film A-2 was changed to the transparent support 3. The rubbing direction was set so as to be substantially perpendicular to the direction in which the in-plane refractive index of the transparent support became maximum.

As for the direction of the rubbing treatment described above, the direction in which the support coated with the alignment film is rubbed linearly when viewed from the alignment film side is regarded as the + direction of the Y axis, and the X axis perpendicular to the direction is defined as the + direction. Similarly, it was set in the plane of the support and used as a reference axis (also referred to as a reference arrangement). Hereinafter, unless otherwise specified, the direction of the rubbing process uses the above-described reference axis (reference arrangement).

<< Method for Evaluating Alignment Characteristics of Liquid Crystalline Compound >> The characteristics of the alignment film according to the optical compensation sheet of the present invention and the alignment characteristics of the polymerizable liquid crystal compound obtained by combining the liquid crystal compound were determined by the following procedure. .

The characteristics of each alignment film were examined using the four types of each alignment film prepared above and the following solutions LC-1 and LC-2. The liquid crystallinity of each of the polymerizable liquid crystalline compounds in the solutions LC-1 and LC-2 expresses an enantiotropic nematic layer.

(Composition of Solution LC-1) MEK (methyl ethyl ketone) 89.5 parts Compound 1 3 parts Compound 2 4 parts Compound 3 3 parts Irgacure 369 (manufactured by Ciba Specialty Chemicals) 1.5 parts

[0099]

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[0100]

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[0101]

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(Composition of Solution LC-2) MEK 88.5 parts Compound 1 5 parts Compound 2 3 parts Compound 3 3 parts Irgacure 369 (manufactured by Ciba Specialty Chemicals) 1.5 parts (Composition of Solution LC-3) MEK (methyl ethyl ketone) 93.5 parts Compound 1 1.5 parts Compound 2 2 parts Compound 3 1.5 parts Irgacure 369 (manufactured by Ciba Specialty Chemicals) 1.5 parts (composition of solution LC-4) MEK 93 Part Compound 1 2.5 parts Compound 2 1.5 parts Compound 3 1.5 parts Irgacure 369 (manufactured by Ciba Specialty Chemicals) 1.5 parts The tilt angle measurement of the alignment film interface of the optically anisotropic layer and the air interface can be performed. This was performed using the crystal rotation method. As a result, the tilt angles of the alignment film and the air interface of each liquid crystal material exhibited characteristics as shown in Tables 1 and 2 below.

First, an alignment process (rubbing process) is performed using a slide glass coated with an alignment film, and the solution L
After applying C-1 and LC-2 on the alignment film, the solvent was dried and the alignment film was adjusted to be anti-parallel. Next, the thickness of the liquid crystal layer was adjusted to 2 μm,
μm and then 10 μm, using a hot stage, observing an orthoscopic image and a conoscopic image in the liquid crystal temperature range, and using an automatic birefringence meter to determine the average tilt angle of each sample when anti-parallel processing was performed. It measured using. Table 1 shows the obtained results.

[0104]

[Table 1]

From Table 1, it is found that both the liquid crystal compound prepared from the liquid crystal solution LC-1 and the liquid crystal compound prepared from the liquid crystal solution LC-2 sandwiched between the alignment films A-1 have a small tilt angle. This indicates that the rod-like liquid crystal molecules sandwiched between the films are in a lying state. On the contrary,
Liquid crystal solutions LC-1, LC sandwiched between alignment films A-2
-2 indicate that the tilt angle is large, that is, the rod-shaped liquid crystal molecules sandwiched between the alignment films A-2 are in a standing state.

Separately from the above, the solutions LC-1 and LC-2 are applied to each alignment film, dried and heat-treated, and the alignment film is disposed on only one surface of the liquid crystal compound, and the other surface is air-conditioned. Samples having various thicknesses to be used as interfaces were prepared, and the same observation and measurement were performed. Table 2 shows the obtained results.

[0107]

[Table 2]

From Table 2, the pretilt angles of the alignment films A-1 and A-2 are about 1 ° and about 65 ° when LC-1 and LC-2 are used, respectively. It was found that the solution LC-2 exhibited a high tilt angle at the interface and a low tilt angle at the air interface.

Further, the liquid crystal solution LC-3 shows the same behavior as the above-mentioned liquid crystal solution LC-1, and the liquid crystal solution LC-4 shows the same behavior as the above-mentioned LC-2.

<< Preparation of Optical Compensation Sheet >> (Preparation of Optical Compensation Sheet 1) The above solution LC-2 was applied on the above-mentioned alignment film A-2 using a wire bar # 4.
The film was dried in the order of 75 ° C. for 30 seconds and 55 ° C. for 20 seconds in a windless state, purged with nitrogen at 98 kPa for 60 seconds, and cured with ultraviolet light of 450 mJ under an oxygen concentration of 0.1%. Produced. 1 thus obtained
The sheet having the optically anisotropic layer was designated as S-1.

Next, an alignment film A-2 was formed on S-1 according to the method described above. At this time, the rubbing direction was in the + X direction with respect to the direction defined in S-1. Then, the above-mentioned solution LC-2 was applied on this alignment film using a wire bar # 4. This is at room temperature for 10 seconds, then 75 seconds for 30 seconds.
After drying in the absence of wind in the order of 55 ° C for 20 seconds,
Nitrogen purge at 98 kPa for 60 seconds and oxygen concentration of 0.1
% And cured with 450 mJ of ultraviolet light to obtain an optical compensation sheet 1 having an optically anisotropic layer in which the orientation of two liquid crystal compounds is fixed on one surface of the transparent support 1 as shown in FIG. Was.

(Preparation of Optical Compensation Sheet 2) A solution LC-1 was applied on the above-mentioned alignment film A-1 using a wire bar # 4. This is at room temperature for 10 seconds, then 7 seconds for 30 seconds.
After drying in the order of 5 ° C. and 55 ° C. for 20 seconds in a windless state, nitrogen purging was performed at 98 kPa for 60 seconds, and a film cured by ultraviolet rays of 450 mJ under an oxygen concentration of 0.1% was produced. Thus, a sheet S-2 having one optically anisotropic layer was obtained. Next, an alignment film A-1 was formed on S-2 according to the method described above. At this time, the rubbing direction is S-
Performed in the + X direction with respect to the direction defined in 2. And
The above solution LC-1 was applied on this alignment film using a wire bar # 4. This is dried at room temperature for 10 seconds, then at 75 ° C. for 30 seconds and then at 55 ° C. for 20 seconds in a windless state, then purged with nitrogen at 98 kPa for 60 seconds, and cured with 450 mJ ultraviolet light under an oxygen concentration of 0.1%. Let
An optical compensatory sheet 2 having an optically anisotropic layer in which the orientation of two liquid crystal compounds was fixed on one surface of the transparent support 1 was obtained.

(Preparation of Optical Compensation Sheet 3) The solution LC-1 was applied on the alignment film A-3 using a wire bar # 4. This is at room temperature for 10 seconds, then 75 seconds for 30 seconds.
After drying in the absence of wind in the order of 55 ° C for 20 seconds,
Nitrogen purge at 98 kPa for 60 seconds and oxygen concentration of 0.1
The composition was cured by UV light of 450 mJ under the% condition to produce an optical compensation sheet 3 as shown in FIG.

(Preparation of Optical Compensation Sheet 4) A solution LC-2 was applied on the alignment film A-4 using a wire bar # 4. This is at room temperature for 10 seconds, then 75 seconds for 30 seconds.
After drying in the absence of wind in the order of 55 ° C for 20 seconds,
Nitrogen purge at 98 kPa for 60 seconds and oxygen concentration of 0.1
The composition was cured by UV light of 450 mJ under the% condition to produce an optical compensation sheet 4.

(Preparation of Optical Compensation Sheet 5) Transparent Support 1
An optical compensatory sheet 5 was produced in the same manner as the optical compensatory sheet 1 except that the transparent support 2 was used.

(Preparation of Optical Compensation Sheet 6) Transparent Support 1
An optical compensatory sheet 6 was produced in the same manner as in the optical compensatory sheet 1 except that the transparent support 3 was used.

<< Preparation of Comparative Optical Compensation Sheet >> (Preparation of Comparative Optical Compensation Sheet 1) On the sheet S-2 prepared by the above-described method, an alignment film A-2 was prepared according to the above-described method, and further described above. LC-2 was applied by the method described above to obtain a comparative optical compensation sheet 1.

(Preparation of Comparative Optical Compensation Sheet 2) An alignment film A-1 was prepared according to the above-described method on the sheet S-1 prepared according to the above-described method, and the solution LC-2 was coated with a wire bar # on the alignment film. 4 was applied. At room temperature for 10 seconds,
Next, drying was performed in the order of 75 ° C. for 30 seconds and 55 ° C. for 20 seconds in a windless state, followed by purging with nitrogen at 98 kPa for 60 seconds and curing with ultraviolet light of 450 mJ under an oxygen concentration of 0.1%. 2 was obtained.

(Preparation of Comparative Optical Compensation Sheet 3) Solution LC-2 was replaced with solution LC in optical compensation sheet 1 described above.
The optical compensation sheet 3 for comparison was produced in the same manner except that the wire bar was changed from # 4 to # 3 (the thickness of the optically anisotropic layer was reduced).

(Preparation of Comparative Optical Compensation Sheet 4) In the preparation of the comparative optical compensation sheet 1 described above, the solution LC
-1 was designated as solution LC-3, solution LC-2 was designated as solution LC-4, and an optical compensation sheet 4 for comparison was produced in the same manner except that the wire bar was changed from # 4 to # 3.

When LC-1 and LC-2 were applied with wire bar # 4, the dry film thickness was 0.8 μm, and when LC-3 and LC-4 were applied with wire bar # 3, the dry film thickness was 0.5 μm. I confirmed that it would be.

Table 3 below shows the characteristics of the produced optical compensation sheets 1 to 6 and comparative optical compensation sheets 1 to 4.

[0123]

[Table 3]

<< Evaluation Method of Viewing Angle >> The viewing angle was measured as described below for each of the optical compensation sheets 1 to 6 and the comparative optical compensation sheets 1 to 4 prepared above.

More specifically, the optical compensatory sheet is bonded so that the axis of the optical compensatory sheet coincides with the transmission axis (light transmission axis) of the polarizing plate. Is NEC's 15-inch display Multi
The optical compensatory sheet previously bonded to the Sync LCD 1525J was peeled off and then attached thereto, and the viewing angle was measured by EZ-contrast manufactured by ELDIM. The viewing angle was represented by the range of the inclination angle from the normal direction to the panel surface where the contrast ratio between white display and black display of the liquid crystal panel was 10 or more.

The optical compensatory sheet 1 shown in FIG. 3 and the optical compensatory sheet 2 shown in FIG. 4 are explanatory diagrams showing the optical compensatory sheet in a state of being bonded to a liquid crystal cell (however, the liquid crystal cell is not shown). ).

In each figure, FIG. 3 (a), FIG.
3A shows a front view of the optical compensatory sheet in a state where the optical compensatory sheet is attached to a liquid crystal cell. FIGS. 3B and 4B show the optical compensatory sheet in a state parallel to one side 5 of the optical compensatory sheet. 1 shows a cross-sectional view when observing.

An arrow 3 shown by a solid line indicates the orientation direction of the liquid crystal compound positioned in front of the viewer, and an arrow 2 shown by a dotted line indicates the orientation of the liquid crystal compound positioned in the back as viewed from the viewer. Shows the orientation direction of the compound. Further, FIG. 3 (c) is a schematic diagram of FIG. 3 (b), and shows a refractive index ellipsoid unit (representing a polymerizable liquid crystal compound, provided that after the orientation is fixed after the polymerization reaction, This indicates so-called hybrid orientation, in which the angle between the film surface (which becomes an optically anisotropic compound) and the film surface becomes smaller toward the upper side (the surface side of the optical compensation sheet).

FIGS. 3A and 4A are explanatory views showing that the orientation directions of the two layers of liquid crystal compounds in the optical compensation sheet of the present invention cross each other. 3 (b) and FIG. 4 (b) show that the angle between the orientation direction of each of the two layers of the liquid crystal compound and the sheet surface with respect to the thickness direction of the optical compensation sheet. FIG. 4 is an explanatory view showing that the liquid crystal compounds of two layers change in the same direction, although the increase or decrease increases or decreases continuously or stepwise.

As a result of viewing angle measurement, each of the optical compensatory sheets of the present invention showed good values of left and right viewing angles of 60 ° or more, 45 ° or more, and 35 ° or more. On the other hand, comparison 4
The optical compensatory sheets 1 to 4 all had significantly different viewing angle characteristics from the left and right directions, and all were significantly inferior to the viewing angle of the optical compensatory sheet of the present invention.

[0131]

According to the present invention, a TN-TFT
Angle Compensation Sheet that can easily improve the viewing angle characteristics of LCD type LCDs, that is, the coloring of the screen when viewed from an oblique direction, and the reversal phenomenon of light and dark, and the viewing angle can be significantly improved with a simple configuration using the same. An improved liquid crystal display device can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of an optical compensation sheet of the present invention.

FIG. 2 is a schematic view showing an example of the optical compensation sheet of the present invention.

FIG. 3A is a schematic view of the optical compensation sheet 1 bonded to a liquid crystal cell and viewed from the front (liquid crystal cell is omitted);
(B) is a cross-sectional view of the optical compensatory sheet 1 when viewed from the side with respect to the front, and (c) shows that the angle formed by the refractive index ellipsoid with the sheet surface decreases as going toward the sheet surface. It is a schematic diagram which shows that it is a hybrid direction.

FIG. 4A is a schematic view when the optical compensatory sheet 2 is bonded to a liquid crystal cell and viewed from the front (the liquid crystal cell is omitted);
FIG. 3B is a cross-sectional view of the optical compensation sheet 2 as viewed from the side with respect to the front.

[Description of Signs] 1 Optical compensatory sheet 2 Orientation direction of liquid crystal compound positioned at the back as viewed from observer 3 Orientation direction of polymerizable liquid crystal compound positioned at the front as viewed from the observer side 4 Optical compensatory sheet One side

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Sota Kawakami In-house Konica Corporation, 1 Sakura-machi, Hino-shi, Tokyo In-house (72) Inventor Nobuyuki Konica Incorporated, 1 Konica Sakura-cho, Hino-shi, Tokyo F-term (reference) 2H049 BA06 BA42 BB03 BB49 BC03 BC04 BC05 BC22 2H091 FA11X FA11Z FB02 FD10 FD15 GA06 HA07 KA05 LA18 LA20

Claims (15)

[Claims] 1. A coating liquid containing a polymerizable liquid crystal compound is applied on a side of a support A having an alignment layer on a side having the alignment layer, or a support having an alignment property (support B) ), And the angle between the optical axis of the applied polymerizable liquid crystalline compound and the surface of the support (including both supports A and B, simply referred to as support). Is obtained by fixing the orientation of the polymerizable liquid crystal compound so that the orientation of the polymerizable liquid crystal compound is reduced continuously or stepwise from the support in the thickness direction of the layer coated with the coating liquid. In an optical compensation sheet in which all of the optically anisotropic layer is adjusted to contain the anisotropic compound, the optically anisotropic compound present at the interface between the alignment layer or the support B and the optically anisotropic layer An optical compensation sheet, wherein an average tilt angle θ is 0 <θ <α / 2 with respect to the tilt angle α. 2. A coating liquid containing a polymerizable liquid crystal compound is applied on the side of the support A having an alignment layer on the side having the alignment layer, or a support having an alignment property (support B) ), And the angle between the optical axis of the applied polymerizable liquid crystalline compound and the surface of the support (including both supports A and B, simply referred to as a support). Is obtained by fixing the orientation of the polymerizable liquid crystalline compound so that the orientation of the polymerizable liquid crystalline compound is increased continuously or stepwise from the support in the thickness direction of the layer coated with the coating liquid. In an optical compensatory sheet in which all of the optically anisotropic layer is adjusted to contain the anisotropic compound, the average tilt angle is relative to the tilt angle β of the optically anisotropic compound present at the interface between the optically anisotropic layer and air. θ is 0 <θ
<Β / 2. 3. A coating liquid containing a polymerizable liquid crystalline compound is applied on the side of the support A having an alignment layer on the side having the alignment layer, or a support having alignment properties (support B) ), And the angle between the optical axis of the applied polymerizable liquid crystalline compound and the surface of the support (including both supports A and B, simply referred to as support). Is obtained by fixing the orientation of the polymerizable liquid crystal compound so that the orientation of the polymerizable liquid crystal compound is reduced continuously or stepwise from the support in the thickness direction of the layer coated with the coating liquid. In an optical compensation sheet in which all of the optically anisotropic layer is adjusted to contain the anisotropic compound, the optical axis of the optically anisotropic compound whose orientation is fixed in the optically anisotropic layer and the optical compensation sheet surface Angle with 4
An optical compensatory sheet comprising at least 5% of the optically anisotropic compound in a range of 0 ° to 50 °. 4. A coating liquid containing a polymerizable liquid crystal compound is applied on the side of the support A having the alignment layer on the side having the alignment layer, or the support having the alignment property (the support B) ), And the angle between the optical axis of the applied polymerizable liquid crystalline compound and the surface of the support (including both supports A and B, simply referred to as a support). Is obtained by fixing the orientation of the polymerizable liquid crystalline compound so that the orientation of the polymerizable liquid crystalline compound is increased continuously or stepwise from the support in the thickness direction of the layer coated with the coating liquid. In an optical compensation sheet in which all of the optically anisotropic layer is adjusted to contain the anisotropic compound, the optical axis of the optically anisotropic compound whose orientation is fixed in the optically anisotropic layer and the optical compensation sheet surface Angle with 4
An optical compensatory sheet comprising at least 5% of the optically anisotropic compound in a range of 0 ° to 50 °. 5. A support (including both supports A and B, simply referred to as a support) having at least two optically anisotropic layers on one or both sides thereof, and the optically compensatory sheet surface of the optically anisotropic layer. The optical compensatory sheet according to claim 1 or 3, wherein the optical slow axes in each of them intersect at 80 ° to 100 °. 6. A support (including both supports A and B, simply referred to as a support) having at least two optically anisotropic layers on one or both sides thereof, and the optically compensatory sheet surface of the optically anisotropic layer. The optical compensatory sheet according to claim 2 or 4, wherein the optical slow axes in the two intersect at 80 ° to 100 °. 7. An optically anisotropic layer having at least one optically anisotropic layer on one side and both sides of a support (including both supports A and B, simply referred to as a support). The optical compensatory sheet according to claim 3 or 4, wherein the optical slow axes in the plane of the compensatory sheet intersect at 80 ° to 100 °. 8. An optically biaxial cellulose ester film is used as a support (including both supports A and B, simply referred to as a support).
The optical compensation sheet according to any one of the above. 9. An optically biaxial cellulose ester film is used as a support (including both supports A and B, simply referred to as a support), and the refractive index of the support in the plane of an optical compensation sheet is determined. The maximum direction and the direction in which the refractive index of the optically anisotropic layer in the plane of the optical compensation sheet is the maximum are 80 ° to 100 °.
The optical compensatory sheet according to any one of claims 1 to 7, wherein the optical compensatory sheet intersects with each other. 10. A support (including both supports A and B;
A direction in which the refractive index in the plane of the optical compensation sheet of the support is maximized, and an optical compensation sheet of at least one optically anisotropic layer is used. The optical compensation sheet according to any one of claims 1 to 9, wherein directions in which the in-plane refractive index is maximum intersect at 80 ° to 100 °. 11. The optical compensation sheet according to claim 1, wherein a rod-shaped liquid crystal compound is used as the polymerizable liquid crystal compound. 12. A support (including both supports A and B;
A support) is an optically biaxial cellulose ester film, the support has an in-plane retardation value (R ₀ ) in the range of 5 to 95 nm, and has a retardation in the thickness direction. Dation value (R _t ) is 15 to 300n
The optical compensatory sheet according to claim 1, wherein the optical compensatory sheet is within a range of m. 13. The method according to claim 1, wherein at least one alignment layer and at least one elution block layer are provided between the support and the optically anisotropic layer.
An optical compensation sheet according to the item. 14. The optical compensation sheet according to claim 13, wherein the elution block layer contains a water-soluble polymer. 15. A method of manufacturing a liquid crystal display device, comprising using the optical compensation sheet according to claim 1 on only one side of the liquid crystal display. Production method.