JP4548036B2 - Optical laminate, polarizing plate, and liquid crystal display device - Google Patents

Description

  The present invention is an optical laminate that can be easily manufactured and has excellent viewing angle characteristics and display quality uniformity over a long period of time, a polarizing plate that has excellent viewing angle performance, and a display performance provided with the same. The present invention relates to an excellent liquid crystal display device.

In recent years, the screen size of liquid crystal displays has been increasing. Along with this, the problem of viewing angle performance has been particularly addressed. This problem is a phenomenon in which when the screen of the liquid crystal display is observed from an oblique direction, brightness, color, contrast, and the like change greatly, and the screen becomes difficult to see.
By the way, in a liquid crystal display, a retardation film is widely used in order to compensate a retardation due to birefringence of a liquid crystal cell. One of the causes of the viewing angle performance problem is that the viewing angle performance of the retardation film is poor. When the retardation film is observed from an oblique direction, the refractive index in the thickness direction of the film affects the retardation film and exhibits a phase difference different from that when viewed from the front. In order to solve this problem, various optical films having a controlled refractive index in the thickness direction have been proposed so far.

  For example, Patent Document 1 discloses a retardation film obtained by stretching a film in which a polymer is oriented in the normal direction of the film in advance. Here, in order to orient the molecules in the film normal direction, a rod is obtained by extruding the molten resin from the nozzle, and further, an operation of cutting it into a plate shape is performed.

  Patent Document 2 discloses that a birefringent film having molecular groups oriented in the thickness direction of the film is obtained by applying a heat treatment after bonding a shrinkable film to the resin film surface to form a laminate. Is disclosed.

  Further, Patent Document 3 discloses that a layer formed by substantially vertically aligning discotic liquid crystalline molecules and a layer formed from molecules having a positive intrinsic birefringence have their in-plane slow axes. A phase difference plate laminated so as to be substantially parallel is disclosed.

  However, the retardation film of Patent Document 1 has a problem that it is difficult to obtain a film having a uniform refractive index characteristic over the entire surface. In addition, the birefringent film of Patent Document 2 must peel the shrink film after stretching, and in addition, it is necessary to precisely control the ratio of stretching and shrinkage, the manufacturing process is complicated, and the productivity is high. There was a low problem.

  Further, the retardation plate of Patent Document 3 is obtained by laminating an optically anisotropic layer and a vertically aligned discotic liquid crystal. However, the support for aligning the discotic liquid crystal is caused by a temperature change in the external environment. There is a problem that the deformation of the discotic liquid crystal is disturbed due to deformation caused by internal stress, and in-plane retardation unevenness and slow axis unevenness are likely to occur. In addition, here, as a method for actually forming a vertical alignment state of liquid crystal, an operation of using a vertical alignment film or transferring a fixed vertical alignment film layer is disclosed. However, the film is damaged by rubbing or transfer processing, or another process such as a vertical alignment film forming operation is newly required.

JP-A-2-160204 JP-A-5-157911 JP 2001-56411 A

  On the other hand, in order to solve the problem of the viewing angle performance, a method for improving the design of the liquid crystal cell itself has been studied, and for example, a method such as an in-plane switching mode has been devised (for example, Patent Document 4). According to this method, the problem of viewing angle performance caused by the liquid crystal molecules in the liquid crystal cell can be improved. However, even with this method, depending on the viewing angle, the arrangement of the polarizing plates may deviate from the crossed Nicols arrangement, which causes the problem of light leakage and a decrease in viewing angle, and a polarizing plate with excellent viewing angle performance is required. Has been.

JP 7-261152 A

  Accordingly, an object of the present invention is to provide a highly durable optical laminate having excellent production efficiency, easily controlling the refractive index, and having uniform optical characteristics over a long period of time, and a viewing angle obtained using the optical laminate. It is an object of the present invention to provide a liquid crystal display device having excellent display performance including a polarizing plate having excellent performance and an optical laminate.

  As a result of diligent research to solve the above problems, the inventors of the present invention have developed a transparent optically anisotropic layer containing a thermoplastic resin and a transparent optically anisotropic layer containing shear-oriented lyotropic liquid crystal molecules. The inventors have found that the above object can be achieved by laminating in a specific direction, and have completed the present invention.

Thus, according to the present invention,
(1) An optical laminate having a first optically anisotropic layer containing a thermoplastic resin and a second optically anisotropic layer containing lyotropic liquid crystal molecules,
The lyotropic liquid crystal molecules of the second layer are aligned in a specific direction substantially perpendicular to the substrate surface by shearing, and the in-plane slow axis of the first layer and the in-plane of the second layer The slow axis is laminated substantially in parallel,
The in-plane retardation measured from the normal direction of the optical laminate (C) with light having a wavelength of 550 nm is Re ₀ , and the normal of the optical laminate (C) is irradiated with light having a wavelength of 550 nm from the normal to the in-plane slow axis direction. An optical laminate characterized by satisfying 0.93 ≦ Re ₄₀ / Re ₀ ≦ 1.07, where Re ₄₀ is a retardation measured from a direction inclined by 40 °,
(2) The optical laminate according to (1), wherein the variation of the in-plane slow axis of the optical laminate is within ± 3 °,
(3) The optical laminate according to (1) or (2), wherein the absolute value of the photoelastic coefficient of the thermoplastic resin of the first layer is 10 × 10 ⁻¹² Pa ⁻¹ or less,
(4) The optical laminated body according to any one of (1) to (3), wherein the lyotropic liquid crystal molecule is represented by (Chemical Formula 1) or (Chemical Formula 2),
(5) The optical layered body according to any one of (1) to (4), wherein the layer (A) contains a norbornene polymer,
(6) The optical layered body according to any one of (1) to (5), wherein the content of the residual volatile component in the layer (A) is 0.1% by weight or less,
( 7 ) A polarizing plate comprising a laminate of the optical laminate according to any one of (1) to ( 6 ) and a polarizing film,
( 8 ) An IPS liquid crystal display device comprising the optical laminate according to any one of (1) to ( 6 ) disposed on at least one side of a liquid crystal cell,
Is to provide.

  The optical layered body of the present invention is excellent in production efficiency, can easily control birefringence, and can stably compensate for a phase difference, so that luminance unevenness and color unevenness are reduced over a long period of time. Furthermore, it can be widely applied to a liquid crystal display device and an organic EL display device as a retardation plate having excellent viewing angle characteristics.

  The optical laminate (C) of the present invention has a first optical anisotropic layer (A) having a thermoplastic resin and a second optical anisotropic layer (B) having a lyotropic liquid crystal molecule.

  The thermoplastic resin used for the first optically anisotropic layer (A) is preferably a thermoplastic resin having a total light transmittance of 70% or more measured for a test piece having a thickness of 1 mm, and 90% or more. More preferably. Examples of such thermoplastic resins include polymers having an alicyclic structure, polyolefin polymers, polycarbonate polymers, polyester polymers such as polyethylene terephthalate, polyvinyl chloride polymers, polystyrene polymers, polyacrylonitrile polymers. , Polysulfone polymer, polyether sulfone polymer, polyarylate polymer, acetate polymer such as triacetyl cellulose, (meth) acrylic acid ester-vinyl aromatic compound copolymer, and the like. Also, a copolymer or polymer mixture of the resin can be used. Among these, a polymer having an alicyclic structure can be suitably used.

  A polymer having an alicyclic structure has an alicyclic structure in the main chain and / or side chain, and has a main chain containing an alicyclic structure from the viewpoint of mechanical strength, heat resistance, and the like. preferable.

  Examples of alicyclic structures include saturated alicyclic hydrocarbon (cycloalkane) structures and unsaturated alicyclic hydrocarbon (cycloalkene) structures. From the viewpoint of mechanical strength and heat resistance, cycloalkane structures and cycloalkane structures can be used. Alkene structures are preferred, with cycloalkane structures being most preferred. The number of carbon atoms constituting the alicyclic structure is not particularly limited, but is usually 4 to 30, preferably 5 to 20, more preferably 5 to 15 in the mechanical strength, The properties of heat resistance and film formability are highly balanced and suitable. The proportion of the repeating unit containing the alicyclic structure in the polymer resin having an alicyclic structure used in the present invention may be appropriately selected according to the purpose of use, but preferably 55% by weight or more. More preferably, it is 70% by weight or more, and particularly preferably 90% by weight or more. When the ratio of the repeating unit having an alicyclic structure in the polymer having an alicyclic structure is within this range, it is preferable from the viewpoint of the transparency and heat resistance of the optical laminate.

Polymers having an alicyclic structure include polymers of norbornenes, polymers of monocyclic olefins, polymers of cyclic conjugated dienes, polymers of vinyl alicyclic hydrocarbons, and these A hydride etc. can be mentioned. Among these, norbornene polymers can be suitably used because of their excellent transparency and moldability.
Examples of the norbornene polymer include a ring-opening polymer of a monomer having a norbornene structure, a ring-opening polymer of a monomer having a norbornene structure and another monomer, a hydride thereof, or a norbornene structure. Examples thereof include addition polymers of monomers, addition polymers of monomers having a norbornene structure and other monomers, and hydrides thereof. Among these, a ring-opening (co) polymer hydride of a monomer having a norbornene structure is particularly suitable from the viewpoints of transparency, moldability, heat resistance, low hygroscopicity, dimensional stability, lightness, and the like. Can be used.

  The thermoplastic resin used for the first optically anisotropic layer (A) includes an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, an antistatic agent, a dispersant, and a chlorine scavenger as necessary. , Flame retardant, crystallization nucleating agent, antiblocking agent, antifogging agent, mold release agent, pigment, organic or inorganic filler, neutralizing agent, lubricant, decomposition agent, metal deactivator, antifouling agent, antibacterial Known additives such as additives, other resins, and thermoplastic elastomers can be added as long as the effects of the invention are not impaired. These additives are generally added in an amount of 0 to 5 parts by weight, preferably 0 to 3 parts by weight, relative to the thermoplastic resin.

The thermoplastic resin used for the first optically anisotropic layer (A) preferably has an absolute value of photoelastic coefficient of 10 × 10 ⁻¹² Pa ⁻¹ or less, and 7 × 10 ⁻¹² Pa ⁻¹ or less. More preferably, it is 4 × 10 ⁻¹² Pa ⁻¹ or less. The photoelastic coefficient C is expressed as follows: birefringence is Δn and stress is σ.
C = Δn / σ
It is a value represented by When the photoelastic coefficient of the optically anisotropic layer (A) exceeds 10 × 10 ⁻¹² Pa ⁻¹ , the liquid crystal of the second optically anisotropic layer (B) is caused by deformation of the optically anisotropic layer (A). The orientation of the molecules is disturbed, and as a result, the in-plane slow axis and in-plane retardation of the optical layered body may vary greatly.

  The thermoplastic resin used for the first optically anisotropic layer (A) preferably has a shrinkage rate of 0.5% or less at 80 ° C. for 6 hours, more preferably 0.3% or less. . When the shrinkage rate at 80 ° C. for 6 hours exceeds 0.5%, the dimensional stability of the optical layered body becomes insufficient, and the optical characteristics may change over time.

  Although it does not restrict | limit especially as a method to manufacture a 1st optically anisotropic layer (A), It is preferable to obtain by extending | stretching the film which consists of the said thermoplastic resin. There is no restriction | limiting in particular in the method of extending | stretching, A conventionally well-known method can be applied. Specifically, uniaxial stretching methods such as a method of uniaxially stretching in the longitudinal direction using a difference in peripheral speed on the roll side, a method of uniaxially stretching in the lateral direction using a tenter, and the like can be mentioned. Moreover, as another method for producing the layer (A), a method in which rod-like liquid crystal molecules are aligned in a predetermined direction on the film made of the thermoplastic resin can also be mentioned.

There is no restriction | limiting in particular as a method of manufacturing the film which consists of the said thermoplastic resin, For example, conventionally well-known methods, such as a solution casting method, an injection molding method, and a melt extrusion method, are mentioned. Among these, the melt extrusion method that does not use a solvent is preferable from the viewpoint of being able to efficiently reduce the amount of residual volatile components in the optically anisotropic layer (A) and being excellent in production efficiency.
Examples of the melt extrusion method include an inflation method using a die, but a method using a T die is preferable in terms of excellent productivity and thickness accuracy.

The content of the residual volatile component in the first optically anisotropic layer (A) is not particularly limited, but is preferably 0.1% by weight or less, more preferably 0.05% by weight or less, and further preferably 0.02%. % By weight or less. When the content of the residual volatile component exceeds 0.1% by weight, the volatile component is released to the outside, causing a dimensional change in the optically anisotropic layer (A) and generating internal stress. The alignment of the liquid crystal molecules in the second optically anisotropic layer (B) is disturbed, and as a result, the optical properties change over time, such as variations in the in-plane slow axis and in-plane retardation of the optical laminate. There is a fear. Therefore, when the content of the volatile component of the optically anisotropic layer (A) is in the above range, the stability of the optical characteristics such that display unevenness of the display of the liquid crystal display device does not occur even when used for a long period of time is excellent. .
The volatile component is a substance having a molecular weight of 200 or less contained in a trace amount in the optically anisotropic layer (A), and examples thereof include a residual monomer and a solvent. The content of the volatile component can be quantified by analyzing the anisotropic layer (A) by gas chromatography as the sum of substances having a molecular weight of 200 or less contained in the anisotropic layer (A).

From the viewpoint of controlling the refractive index in the in-plane direction of the optical layered body, the first optically anisotropic layer (A) is the main layer in the thickness direction of the optically anisotropic layer (A) measured with light having a wavelength of 550 nm. When the refractive index is nz _A and the main refractive indices in two directions perpendicular to the thickness direction are nx _A and ny _A (where nx _A > ny _A ), {(nx _A −nz _A ) / ( nx _A −ny _A )} ≧ 1 is preferably satisfied.

The first optically anisotropic layer (A) has an in-plane slow axis variation of preferably within ± 3 °, more preferably within ± 1 °, and particularly preferably within ± 0.3 °. It is. By setting the range of variation of the in-plane slow axis of the optically anisotropic layer (A) within the above range, the variation of the in-plane slow axis of the optical laminate of the present invention can be reduced.
The variation of the slow axis is the variation of each measured value with respect to the arithmetic average value of the measured values when the slow axis is measured at several points.

The first optically anisotropic layer (A) has an in-plane retardation variation within 10 nm, preferably within 5 nm, and more preferably within 2 nm. By setting the variation of the in-plane retardation within the above range, the variation of the in-plane retardation of the optical layered body of the present invention can be reduced.
The variation in in-plane retardation is obtained when the in-plane retardation at a light incident angle of 0 ° (in which the incident light beam and the optically anisotropic layer (A) surface are orthogonal) is measured in the width direction of the optical laminate. The difference between the maximum value and the minimum value of the in-plane retardation.

  The liquid crystal molecules used for the second optically anisotropic layer (B) are lyotropic liquid crystal molecules. The lyotropic liquid crystal molecule refers to a molecule that exhibits liquid crystallinity when dissolved in a specific solvent in a specific concentration range. Further, the lyotropic liquid crystal molecules used in the present invention have a characteristic of being oriented in a specific direction by shearing. Furthermore, from the viewpoint of reducing display unevenness of the display device, it is preferable that the orientation is uniform. In particular, from the viewpoint of controlling the refractive index in the thickness direction of the optical laminate, it is preferable that the liquid crystal molecules are aligned substantially perpendicular to the substrate surface. The term “substantially vertical alignment” means that liquid crystal molecules are aligned at an average inclination angle in the range of 50 to 90 ° with respect to the substrate surface. Furthermore, it is preferable that the lyotropic liquid crystal molecules of the present invention have substantially no absorption in the visible light region. Specific examples of such lyotropic liquid crystal molecules are shown below.

  The method for producing the second optically anisotropic layer (B) is not particularly limited, and there is a method in which the lyotropic liquid crystal molecules used in the present invention are aligned by shearing on the surface of a film or plate made of glass or resin. Although mentioned, from a viewpoint of weight reduction, thickness reduction, manufacturing efficiency, etc., the method of carrying out the shear orientation of the lyotropic liquid crystal molecule on the (A) layer surface is preferable.

  As a method for aligning the lyotropic liquid crystal molecules used in the present invention by shearing, a lyotropic liquid crystal molecule dissolved in a solvent described later or a solution containing the additive and the additive described later is applied on a transparent substrate and fixed. A method is mentioned. In this alignment treatment, an alignment film is not used because it is excellent in production efficiency, can achieve weight reduction and thinning, and can prevent damage to the base material and can be applied with a uniform thickness. Is preferred. Examples of the transparent substrate include films and plates made of glass or resin having a total light transmittance of 70% or more.

Examples of the solvent used for dissolving the lyotropic liquid crystal molecules used in the present invention include water and organic solvents. Examples of the organic solvent include amides such as N, N-dimethylformamide; sulfoxides such as dimethyl sulfoxide; heterocyclic compounds such as pyridine; hydrocarbons such as benzene and hexane; alkyl halides such as chloroform and dichloromethane; Esters such as butyl; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and 1,2-dimethoxyethane. Two or more organic solvents may be used in combination.
The concentration in the case where the lyotropic liquid crystal molecules used in the present invention are dissolved in a solvent is not particularly limited as long as the molecules used in the layer (B) exhibit liquid crystallinity. It is added in the range of 0001 to 100 parts by weight, more preferably in the range of 0.0001 to 1 part by weight.

  In the solution containing the lyotropic liquid crystal, a polymerization initiator, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, an antistatic agent, a dispersant, a chlorine scavenger, a flame retardant, a crystal, if necessary. Nucleating agent, antiblocking agent, antifogging agent, release agent, pigment, organic or inorganic filler, neutralizing agent, lubricant, decomposition agent, metal deactivator, antifouling material, plasticizer, adhesive, Known additives such as antibacterial agents, other resins, and thermoplastic elastomers can be added as long as the effects of the invention are not impaired. These additives are usually added in an amount of 0 to 5 parts by weight, preferably 0 to 3 parts by weight, with respect to the solvent for dissolving the lyotropic liquid crystal.

  The solution containing the lyotropic liquid crystal can be applied by a known method such as an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, or a die coating method.

  The lyotropic liquid crystal molecules aligned by shearing are fixed while maintaining the alignment state. Examples of the immobilization method include solvent removal by drying, a polymerization reaction, a combination of these methods, and the like. Examples of the polymerization reaction include a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator.

The second optically anisotropic layer (B) is an optically anisotropic layer (B) measured with light having a wavelength of 550 nm from the viewpoint of controlling the in-plane direction and the refractive index in the thickness direction of the optical laminate. When the main refractive index in the thickness direction is nz _B and the main refractive indexes in two directions perpendicular to the thickness direction are nx _B and ny _B (where nx _B > ny _B ), preferably {(nx _{B -nz B) / (nx B} -ny B)} <1 the filled, still more preferably satisfies the _{0 ≦ {(nx B -nz B} ) / (nx B -ny B)} <1, most preferably 0 ≦ satisfy _{{(nx B -nz B) /} (nx B -ny B)} ≦ 0.5.

The second optically anisotropic layer (B) has an in-plane slow axis variation of preferably within ± 3 °, more preferably within ± 1 °, and particularly preferably within ± 0.3 °. It is. By setting the range of the in-plane slow axis within the above range, the variation in the in-plane slow axis of the optical layered body of the present invention can be reduced.
The variation of the slow axis is the variation of each measured value with respect to the arithmetic average value of the measured values when the slow axis is measured at several points.

The second optically anisotropic layer (B) has an in-plane retardation variation within 10 nm, preferably within 5 nm, and more preferably within 2 nm. By setting the variation of the in-plane retardation within the above range, the variation of the in-plane retardation of the optical layered body of the present invention can be reduced.
The variation in in-plane retardation is obtained when the in-plane retardation at a light incident angle of 0 ° (in which the incident light beam and the surface of the optically anisotropic layer (B) are orthogonal) is measured in the width direction of the optical laminate. The difference between the maximum value and the minimum value of the in-plane retardation.

  The optical layered body of the present invention is formed by laminating the in-plane slow axis of the (A) layer and the in-plane slow axis of the (B) layer substantially in parallel. Substantially parallel means that when the optical laminate (C) is observed from the normal direction of the laminate plane, the average in-plane slow axis of the (A) layer and the average in-plane slow phase of the (B) layer It means that the angle made with the axis is 0-2 °.

The optical laminate (C) of the present invention has an in-plane retardation measured with light having a wavelength of 550 nm from the normal direction of the surface of the optical laminate (C), Re ₀ , and the optical laminate (C) with light having a wavelength of 550 nm. When the retardation measured from a direction inclined by 40 ° from the normal to the in-plane slow axis direction is Re ₄₀ , 0.93 ≦ Re ₄₀ / Re ₀ ≦ 1.07 is satisfied. Furthermore, it is preferable that 0.95 ≦ Re ₄₀ / Re ₀ ≦ 1.05 is satisfied, and it is particularly preferable that 0.99 ≦ Re ₄₀ / Re ₀ ≦ 1.01 is satisfied. By satisfying 0.93 ≦ Re ₄₀ / Re ₀ ≦ 1.07, the incident angle dependency of the retardation value of the optical laminate can be reduced, and the deviation of the crossed Nicols arrangement of the polarizing plate can be reduced. . By satisfying 0.95 ≦ Re ₄₀ / Re ₀ ≦ 1.05, the incident angle dependency of the retardation value of the optical laminate is further reduced, and the deviation of the crossed Nicols arrangement of the polarizing plate is further reduced. Can do. Furthermore, by satisfying 0.99 ≦ Re ₄₀ / Re ₀ ≦ 1.01, the dependency on the incident angle of the retardation value of the optical laminate is substantially eliminated, and the same phase difference is given from any angle. In addition to being able to do so, there is no change in the crossed Nicols arrangement of the polarizing plate from any angle.

In the optical layered body (C) of the present invention, the variation of the in-plane slow axis is preferably within ± 3 °, more preferably within ± 1 °, and particularly preferably within ± 0.3 °. . By making the range of the in-plane slow axis in the above range, when the optical laminate of the present invention is used as a retardation film and bonded to a polarizing plate in a liquid crystal display device, excellent color unevenness and color loss are not caused. Liquid crystal display can be provided.
The variation of the slow axis is the variation of each measured value with respect to the arithmetic average value of the measured values when the slow axis is measured at several points.

The in-plane retardation Re ₀ of the optical layered body (C) of the present invention is not particularly limited, but is preferably 20 to 1000 nm. Here, the in-plane retardation is such that the thickness of the optical laminate (C) is d, the main refractive index in the in-plane slow axis direction is Σnx, and the main refractive index in the in-plane fast axis direction is Σny, This is a value represented by (Σnx−Σny) × d. However, when the thicknesses of the A layer and the B layer are d _A and d _B , Σnx = (nx _A × d _A + nx _B × d _B ) / (d _A + d _B ); Σ ny = (ny _A × d _A + Ny _B × d _B ) / (d _A + d _B ). Here, it is assumed that the directions of the main refractive indexes of the layers substantially coincide with each other.
In the optical layered body (C) of the present invention, the variation in the in-plane retardation Re ₀ is within 10 nm, preferably within 5 nm, and more preferably within 2 nm. By setting the variation of the in-plane retardation within the above range, it is possible to improve the display quality when used as a retardation film for a liquid crystal display device. Here, the variation in in-plane retardation is measured when the in-plane retardation at the time of light incident angle 0 ° (incident light beam and the surface of the laminate of the present invention are orthogonal) is measured in the width direction of the optical laminate. The difference between the maximum value and the minimum value of the in-plane retardation.

The optical laminate (C) of the present invention has a refractive index in the thickness direction of the optical laminate measured with light having a wavelength of 550 nm as Σnz, and refractive indexes in two directions perpendicular to the thickness direction as Σnx and Σny. (Where Σnx> Σny) (where the thicknesses of the A and B layers are d _A and d _B , Σnx = (nx _A × d _A + nx _B × d _B ) / (d _A + d) _{B); Σny = (ny a} × d a + ny B × d B) / (d a + d B); and _{Σnz = (nz a × d a} + nz B × d B) / (d a + d B)), It is preferable to satisfy 0 <{(Σnx−Σnz) / (Σnx−Σny)} <1. Furthermore, it is preferable to satisfy 0.4 <{(Σnx−Σnz) / (Σnx−Σny)} <0.6. By satisfying 0 <{(Σnx−Σnz) / (Σnx−Σny)} <1, The incident angle dependence of the retardation value of the optical laminate is reduced, and the deviation of the crossed Nicols arrangement of the polarizing plate can be reduced. By satisfying 0.6 <{(Σnx−Σnz) / (Σnx−Σny)} <0.4, the incident angle dependency of the retardation value of the optical laminate is further reduced, and the crossed Nicols of the polarizing plate The displacement of the arrangement can be further reduced.

Since the optical laminate (C) of the present invention can be easily manufactured and highly compensated for birefringence, it can be used as a retardation plate or a viewing angle compensation film alone or in combination with other members. It can be widely applied to devices, organic EL display devices, plasma display devices, FED (field emission) display devices, SED (surface electric field) display devices, and the like. Examples of the liquid crystal display device include an in-plane switching (IPS) mode, a vertical alignment (VA) mode, a multi-domain vertical alignment (MVA) mode, a continuous spin wheel alignment (CPA) mode, a hybrid alignment nematic (HAN) mode, Examples include a twisted nematic (TN) mode, a super twisted nematic (STN) mode, and an optically compensated bend (OCB) mode. Among these, it can be particularly preferably applied to the IPS mode.
In the IPS mode, liquid crystal molecules that are homogeneously aligned in the horizontal direction and two polarizing films whose transmission axes point vertically and horizontally with respect to the front of the screen are used. When the screen is viewed obliquely from the left and right directions, the two transmission axes are in a positional relationship so that they are perpendicular to each other, and the homogeneously aligned liquid crystal layer has little birefringence that occurs in the twisted mode liquid crystal layer, so that there is sufficient contrast. can get. On the other hand, when the screen is viewed obliquely from the direction of the azimuth angle of 45 °, since the angle formed by the transmission axes of the two polarizing films is shifted from 90 °, the linearly polarized light is not completely blocked. Light leakage occurs, and sufficient black cannot be obtained, resulting in a decrease in contrast. By arranging the optical laminate (C) of the present invention between the two polarizers of the IPS mode liquid crystal display device, the angle formed by the transmission axes of the two polarizers can be observed from any angle. Compensation can be made to be 90 °. Accordingly, it is possible to effectively compensate for the birefringence generated in the transmitted light to prevent light leakage and to obtain high contrast at all azimuth angles. This effect is considered to be the same in other mode liquid crystal display devices, and the effect is particularly remarkable in the IPS mode.
In the liquid crystal display device of the present invention, when forming the liquid crystal display device, for example, a prism array sheet, a lens array sheet, a light diffusing plate, a backlight, a brightness enhancement film, etc. The above can be arranged. Examples of the backlight include a cold cathode tube, a light emitting diode, and an EL.

The polarizing plate having the optical laminate (C) of the present invention is formed by laminating the optical laminate (C) on at least one surface of the polarizing film. For the polarizing film, a film made of a suitable vinyl alcohol polymer such as polypinyl alcohol or partially formalized polyvinyl alcohol, etc., dyeing treatment with a dichroic substance such as iodine or dichroic dye, stretching Appropriate treatments such as treatment and cross-linking treatment can be performed in an appropriate order and manner, and appropriate materials that transmit linearly polarized light when natural light is incident can be used. In particular, those excellent in light transmittance and degree of polarization are preferable. The thickness of the polarizing film is generally 5 to 80 μm, but is not limited thereto.
As a lamination | stacking form, an optical laminated body (C) may be laminated | stacked on both surfaces of a polarizing film, may be laminated | stacked on one side, and there is no limitation in particular in the number of lamination | stacking, You may laminate | stack two or more sheets. Moreover, as a lamination | stacking method, although it is not an essential method, it can laminate | stack using an adhesive agent. Another member can be interposed between the optical laminate (C) and the polarizing film as long as the characteristics of the present invention are not impaired. Further, the lamination direction is not particularly limited, but from the viewpoint of excellent effect of improving the viewing angle of the polarizing plate, the absorption axis of the polarizing film and the slow axis of the optical laminate (C) may be laminated orthogonally or in parallel. Preferably, it is more preferable to laminate them orthogonally.

For the purpose of protecting the polarizing film, a protective film may be bonded to one side or both sides of the polarizing film via an appropriate adhesive layer. An appropriate transparent film can be used as the protective film. Among them, a film having a resin excellent in transparency, mechanical strength, thermal stability, moisture shielding property, etc. is preferably used. Examples of the resin include an acetate polymer such as triacetyl cellulose, a polymer having an alicyclic structure, a polyolefin polymer, a polycarbonate polymer, a polyester polymer such as polyethylene terephthalate, a polyvinyl chloride polymer, and a polystyrene polymer. Polyacrylonitrile polymer, polysulfone polymer, polyether sulfone polymer, polyamide polymer, polyimide polymer, acrylic polymer and the like.
In the present invention, when the optical laminate (C) is in contact with the polarizing film, the optical laminate (C) can also be used as a protective film for the polarizing film. By using the optical laminate (C) also as a protective film for the polarizing film, it is possible to reduce the thickness of the liquid crystal display device by omitting one protective film and to improve the durability of the polarizing film.

The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.
Parts and% are based on weight unless otherwise specified.
Evaluation in this example is performed by the following method.
(1) Thickness The cross section of the film is observed with an optical microscope and measured for each layer.
(2) In-plane retardation Re ₀ measured from the normal direction of the film or laminate surface measured with light having a wavelength of 550 nm, In-plane slow axis direction from the normal direction of the film or laminate surface measured with light having a wavelength of 550 nm Retardation Re ₄₀ , in-plane retardation Re ₀ variation, slow axis direction, slow axis variation, and slow axis cross angle Measured using KOBRA-21).
The variation of the in-plane retardation Re ₀ is determined by measuring the in-plane retardation at intervals of 10 mm in the width direction of the film or laminate, and taking the arithmetic average value of the measured values as the center value of the in-plane retardation. Then, the difference between the maximum value and the minimum value among the measured values is regarded as variation in in-plane retardation.
Further, regarding the variation of the slow axis, the slow axis is measured at intervals of 10 mm in the width direction of the film or laminate, and the arithmetic average value of the measured values is set as the center value of the in-plane slow axis. Then, the difference between the maximum value and the minimum value among the measured values is defined as the variation of the in-plane slow axis.
In measuring the A layer and the B layer, the optically anisotropic layer (A) and the optically anisotropic layer (B) are obtained separately.
(3) The main refractive index Σnz in the thickness direction measured with light having a wavelength of 550 nm, the main refractive index Σnx in the in-plane slow axis direction, and the main refractive index in the direction orthogonal to the in-plane slow axis direction Σny
The optically anisotropic layer (A) and the optically anisotropic layer (B) are separated, and the main refractive indices of the A layer and the B layer are respectively determined by an automatic birefringence meter (manufactured by Oji Scientific Instruments, KOBRA-21). after calculating the following _{formula; Σnx = (nx a × d} a + nx B × d B) / (d a + d B); Σny = (ny a × d a + ny B × d B) / (d a + d B ); Σnz = determined by _{(nz A × d A + nz} B × d B) / (d A + d B).
(4) Photoelastic coefficient The optically anisotropic layer (A) is separated from the optical laminate, and the thermoplastic resin of the layer (A) is measured using a photoelasticity measuring device [Phild-10A, manufactured by UNIOPT Co., Ltd.]. taking measurement.
(5) Shrinkage The optically anisotropic layer (A) is separated from the optical laminate, and a square test piece of 100 mm in the longitudinal direction and 100 mm in the width direction is cut out from the (A) layer, and 6 hours in a dry oven at 80 ° C. Heat. About the sample before a heating and after a heating, the dimension of a longitudinal direction and the width direction is measured using a universal projector, and shrinkage | contraction rate is calculated | required by following Formula.
Shrinkage rate (%) = {(dimension before heating−dimension after heating) / dimension before heating} × 100
(6) Residual volatile component amount The optically anisotropic layer (A) was separated from the optical laminate, and 200 mg of the test piece of the (A) layer was cut out to remove the moisture and organic substances adsorbed on the surface completely. Place in a 4 mm glass tube sample container. Next, the container is heated at a temperature of 100 ° C. for 60 minutes, and the gas coming out of the container is continuously collected. The collected gas is analyzed by a thermal desorption gas chromatography mass spectrometer (TDS-GC-MS), and the total amount of components having a molecular weight of 200 or less is used as a residual volatile component.
(7) Display performance A polarizing plate including the optical layered body is cut into an appropriate size and replaced with an incident-side polarizing plate of a commercially available IPS type liquid crystal display device. At this time, the axial arrangement relationship of the polarizing plate including the optical laminate is the same as that of the original polarizing plate. Moreover, it arrange | positions so that an optical laminated body may be located in the liquid crystal cell side. Thereafter, the display characteristics are visually observed. Also, the background of the display device is displayed in black, and it is confirmed that there is no luminance unevenness (white spots) when viewed from the front direction and an oblique direction within 45 ° in the vertical and horizontal directions in the dark room.
(8) Aging test A polarizing plate including the optical laminate is cut out to an appropriate size, and replaced with an incident-side polarizing plate of a commercially available IPS liquid crystal display device. At this time, the axial arrangement relationship of the polarizing plate including the optical laminate is the same as that of the original polarizing plate. Moreover, it arrange | positions so that an optical laminated body may be located in the liquid crystal cell side. Thereafter, after 200 cycles of a heat cycle test of 1 hour under an environment of 85 ° C. and 90% RH and 1 hour under an environment of −20 ° C. and 40% RH, the image of the display device is visually observed from the front.
Good: No abnormality is observed.
Defect: Partial hue change is observed at the edge of the screen.

(Production Example 1) Production of optically anisotropic layer A1 A pellet of a norbornene polymer (manufactured by Nippon Zeon Co., Ltd., “ZEONOR1420”, glass transition temperature is 136 ° C.), which is an example of a polymer having an alicyclic structure, For 4 hours at 100 ° C. And this pellet is extruded using a T-die type film melt extrusion molding machine having a resin melt kneader equipped with a 50 mmφ screw, under the conditions of a molten resin temperature of 260 ° C. and a T-die width of 650 mm. A film a1 of 100 μm was obtained. This film a1 was wound up into a roll to obtain a roll-shaped body.
The roll wound body of the optically anisotropic layer A1 was obtained by performing lateral uniaxial stretching of the roll wound body of the film a1 at a stretching temperature of 141 ° C., a stretching ratio of 1.8 times, and a stretching speed of 22 mm / min. . The optically anisotropic layer A1 had a slow axis in the width direction.

(Production Example 2) Production of optically anisotropic layer A2 Using a pellet of a norbornene polymer (manufactured by Nippon Zeon Co., Ltd., “ZEONOR1600”, glass transition temperature is 163 ° C.) as a polymer having an alicyclic structure, a molten resin A film a2 having a thickness of 100 μm was obtained in the same manner as in Production Example 1 except that the temperature was 270 ° C. This film a2 was wound up into a roll shape to obtain a roll-shaped body.
The roll wound body of the optically anisotropic layer A2 was obtained by subjecting the roll wound body of the film a2 to longitudinal uniaxial stretching at a stretching temperature of 165 ° C., a stretching ratio of 1.7 times, and a stretching speed of 21 mm / min. . The optically anisotropic layer A2 had a slow axis in the longitudinal direction.

(Production Example 3) Production of optically anisotropic layer A3 Using a resin of polycarbonate polymer (“Panlite L1225Y”, glass transition temperature 150 ° C., manufactured by Teijin Chemicals Ltd.), the melt resin temperature was set to 265 ° C. Produced a film a3 having a thickness of 100 μm in the same manner as in Production Example 1. This film a3 was wound up into a roll to obtain a roll-shaped body.
The roll wound body of the optically anisotropic layer A3 was obtained by performing longitudinal uniaxial stretching of the roll wound body of the film a3 at a stretching temperature of 152 ° C., a stretching ratio of 1.6 times, and a stretching speed of 15 mm / min. . The optically anisotropic layer A3 had a slow axis in the longitudinal direction.

(Production Example 4) Production of optically anisotropic layer A4 Using a resin of norbornene polymer (manufactured by Zeon Corporation, “ZEONOR1420”, glass transition temperature is 136 ° C.) which is an example of a polymer having an alicyclic structure. A film a4 having a thickness of 100 μm was obtained by a solution casting method. This film a4 was wound up into a roll to obtain a roll-shaped body.
The roll wound body of the film a4 was subjected to longitudinal uniaxial stretching at a stretching temperature of 140 ° C., a stretching ratio of 1.6 times, and a stretching speed of 15 mm / min to obtain a roll wound body of the optically anisotropic layer A4. . The optically anisotropic layer A4 had a slow axis in the longitudinal direction.

Example 1 Production of Optical Laminate C1 A solution of lyotropic liquid crystal molecules 5% and water 95% shown in the above (Chemical Formula 1) was used on a long optically anisotropic layer A1 without using an alignment film. Then, it was applied by shearing with a die coater in parallel with the longitudinal direction. This was left still in a 115 ° C. hot atmosphere (substituted with argon) to remove water.
The obtained optical layered body C1 had an in-plane retardation of 274 nm and a slow axis in the width direction. Further, when the lyotropic liquid crystal layer (optically anisotropic layer B1) was peeled off from the optical laminate C1 and the optical properties of the B1 layer were measured, the optically anisotropic layer B1 has a slow axis in the width direction. It was. Table 1 shows the measurement results of the optical laminate C1.

(Example 2) Manufacture of optical laminated body C2 A solution of 8% lyotropic liquid crystal molecules and 92% water shown in the above (Chemical Formula 2) on an optically isotropic glass substrate (thickness 1 mm) having a length of 20 cm and a width of 10 cm. Then, without using an alignment film, it was applied in a shearing manner by a bar coater in parallel to the lateral direction to obtain an optically anisotropic layer B2. This was left still under a 140 ° C. hot atmosphere (substituted with argon) to remove water. The obtained optical laminate B2 had a slow axis in the longitudinal direction.
Further, a 40 mm long / 30 cm wide plate film cut out from the optically anisotropic layer A2 (the longitudinal direction of the optically anisotropic layer A2 coincided with the longitudinal direction of the plate film) The layers B2 were laminated on the lyotropic liquid crystal molecular layer side with their longitudinal directions parallel to each other.
The obtained optical laminate C2 had an in-plane retardation of 273 nm and had a slow axis in the longitudinal direction. Table 1 shows the measurement results of the optical laminate C2.

(Comparative example 1) Manufacture of optical laminated body c1 The discotic liquid crystal molecule 34.1% shown below (chemical formula 3), cellulose acetate butyrate 0.7%, modified trimethylolpropane triacrylate 3.2%, and methyl ethyl ketone 62 A 0.0% solution was shear-coated on the long optically anisotropic layer A1 by a die coater in parallel with the longitudinal direction without using an alignment film. This was left still under a 105 ° C. hot atmosphere (substituted with argon) to remove the solvent.
The obtained optical laminate c1 had an in-plane retardation of 136 nm and a slow axis in the width direction. Further, when the discotic liquid crystal layer (optically anisotropic layer b1) was peeled from the optical laminate c1 and the optical properties of the b1 layer were measured, the slow axis of the optically anisotropic layer b1 could not be measured. Table 1 shows the measurement results of the optical laminate c1.

(Comparative example 2) Manufacture of optical laminated body c2 A solution of 10% rod-like liquid crystal molecules and 90% water shown in the following (Chemical Formula 4) on the long optically anisotropic layer A2 without using an alignment film In parallel with the longitudinal direction, it was applied by shearing with a die coater. This was left still in a 115 ° C. hot atmosphere (substituted with argon) to remove water.
The obtained optical laminate c2 had an in-plane retardation of 272 nm and had a slow axis in the longitudinal direction. Further, when the rod-like liquid crystal layer (optically anisotropic layer b2) was peeled from the optical laminate c2 and the optical characteristics of the b2 layer were measured, the optically anisotropic layer b2 had a slow axis in the longitudinal direction. . Table 1 shows the measurement results of the optical laminate c2.

Comparative Example 3 Production of Optical Laminate c3 A solution of 2% of the lyotropic liquid crystal molecules of (Chemical Formula 1) and 98% of water was formed on the long optically anisotropic layer A3 without using an alignment film. In parallel with the longitudinal direction, it was applied by shearing with a die coater. This was left still in a 115 ° C. hot atmosphere (substituted with argon) to remove water.
The obtained optical layered body c3 had an in-plane retardation of 270 nm and a slow axis in the longitudinal direction. Further, when the lyotropic liquid crystal layer (optically anisotropic layer b3) was peeled from the optical laminate c3 and the optical characteristics of the b3 layer were measured, the optically anisotropic layer b3 had a slow axis in the width direction. It was. Table 1 shows the measurement results of the optical laminate c3.

Comparative Example 4 Production of Optical Laminate c4 A solution of 3% of the lyotropic liquid crystal molecules (97) and 97% of water was used on the long optically anisotropic layer A4 without using an alignment film. In parallel with the longitudinal direction, it was applied by shearing with a die coater. This was left still in a 115 ° C. hot atmosphere (substituted with argon) to remove water.
The obtained optical layered body c4 had an in-plane retardation of 271 nm and a slow axis in the longitudinal direction. Further, when the lyotropic liquid crystal layer (optically anisotropic layer b4) was peeled from the optical laminate c4 and the optical properties of the b4 layer were measured, the optically anisotropic layer b4 had a slow axis in the width direction. It was. Table 1 shows the measurement results of the optical laminate c4.

(Example 3) Manufacture of polarizing plate D1 Roll the slow axis of the roll-shaped optical laminate C1 obtained in Example 1 and a roll-shaped polarizing element (manufactured by Sanlitz, HLC2-5618S, thickness 180 μm). By laminating by a two-roll method, a roll-shaped polarizing plate D1 was obtained. At this time, the angle formed by the slow axis of the optical laminate C1 and the absorption axis of the polarizing element was 90 °.
The display performance of the obtained roll-shaped polarizing plate D1 was evaluated. As a result of the evaluation, a good display could be confirmed both when the display screen was viewed from the front and when viewed from an oblique direction within 40 ° in the vertical and horizontal directions, and the in-plane display characteristics were uniform. Further, the luminance unevenness was not seen from an oblique direction within 40 ° in the vertical and horizontal directions even when viewed from the front. Even when viewed in a range exceeding 40 °, good display could be confirmed.

(Example 4) Manufacture of polarizing plate D2 The slow axis of the optical laminate C2 obtained in Example 2 and the absorption axis of a polarizing element (manufactured by Sanlitz, HLC2-5618S, thickness 180 μm) were orthogonally laminated. A polarizing plate D2 was obtained.
The display performance of the obtained roll-shaped polarizing plate D2 was evaluated. As a result of the evaluation, a good display could be confirmed both when the display screen was viewed from the front and when viewed from an oblique direction within 40 ° in the vertical and horizontal directions, and the in-plane display characteristics were uniform. Further, the luminance unevenness was not seen from an oblique direction within 40 ° in the vertical and horizontal directions even when viewed from the front. When viewed in a range exceeding 40 °, a slight inversion of the gradation was observed in part.

(Comparative Example 5) Production of Polarizing Plate d1 A polarizing plate d1 was prepared in the same manner as in Example 3 except that the roll-shaped optical laminated body c1 obtained in Comparative Example 1 was used instead of the optical laminated body C1. Obtained. At this time, the angle formed by the slow axis of the optical laminate c1 and the absorption axis of the polarizing element was 0 °.
The display performance of the obtained roll-shaped polarizing plate d1 was evaluated. As a result of evaluation, even when the display screen was viewed from the front, the display was uneven even when viewed from an oblique direction within 40 ° in the vertical and horizontal directions, and a display defect occurred when viewed from an oblique direction. The luminance unevenness was also seen in the front direction when viewed from an oblique direction within 40 ° in the vertical and horizontal directions.

(Comparative Example 6) Manufacture of Polarizing Plate d2 A polarizing plate d2 was prepared in the same manner as in Example 3 except that the roll-shaped optical laminated body c2 obtained in Comparative Example 2 was used instead of the optical laminated body C1. Obtained. At this time, the angle formed by the slow axis of the optical laminate c2 and the absorption axis of the polarizing element was 0 °.
The display performance of the obtained roll-shaped polarizing plate d2 was evaluated. As a result of evaluation, there was no display unevenness even when the display screen was viewed from the front and from an oblique direction within 40 ° in the vertical and horizontal directions, but a display defect occurred when viewed from an oblique direction. Although the luminance unevenness was not seen in the front direction, it was seen when viewed from an oblique direction within 40 ° in the vertical and horizontal directions.

(Comparative Example 7) Manufacture of Polarizing Plate d3 A polarizing plate d3 was prepared in the same manner as in Example 3 except that the roll-shaped optical laminated body c3 obtained in Comparative Example 3 was used instead of the optical laminated body C1. Obtained. At this time, the angle formed by the slow axis of the optical laminate c3 and the absorption axis of the polarizing element was 0 °.
The display performance of the obtained roll-shaped polarizing plate d3 was evaluated. As a result of evaluation, even when the display screen was viewed from the front, the display was uneven even when viewed from an oblique direction within 40 ° in the vertical and horizontal directions, and a display defect occurred when viewed from an oblique direction. The luminance unevenness was also seen in the front direction when viewed from an oblique direction within 40 ° in the vertical and horizontal directions.

(Comparative example 8) Manufacture of polarizing plate d4 A polarizing plate d4 is manufactured in the same manner as in Example 3 except that the roll-shaped optical laminated body c4 obtained in Comparative Example 4 is used instead of the optical laminated body C1. Obtained. At this time, the angle formed by the slow axis of the optical laminate c4 and the absorption axis of the polarizing element was 0 °.
The display performance of the obtained roll-shaped polarizing plate d4 was evaluated. As a result of evaluation, there was no display unevenness even when the display screen was viewed from the front and from an oblique direction within 40 ° in the vertical and horizontal directions, but a display defect occurred when viewed from an oblique direction. The luminance unevenness was also seen in the front direction when viewed from an oblique direction within 40 ° in the vertical and horizontal directions.

From the results in Table 1, the following can be understood.
As shown in Example 1, the optical laminate (C) of the present invention is laminated so that the crossing angle between the optically anisotropic layer (A) and the optically anisotropic layer (B) is 0 degree. Re ₄₀ / Re ₀ = 1.0004, variation of slow axis is ± 0.05 degrees or less, variation of in-plane retardation is 0.5 nm, light of thermoplastic resin of optically anisotropic layer (A) The elastic modulus is 3 × 10 ⁻¹² Pa ⁻¹ and the residual volatile component amount of the optically anisotropic layer (A) is 0.01% or less. Therefore, when the optical laminate of the present invention is used for a liquid crystal display device and the display performance is confirmed, a good display can be confirmed not only from the front direction but also from an oblique direction within 40 ° up and down, left and right. The display characteristics are also good, there is no luminance unevenness, and the display characteristics are good for a long time. Even when viewed in a range exceeding 40 °, a good display can be confirmed.
As shown in Example 2, the optical laminate (C) of the present invention was laminated so that the crossing angle between the optically anisotropic layer (A) and the optically anisotropic layer (B) was 0 degree. Re ₄₀ / Re ₀ = 0.966, variation of slow axis is ± 0.1 degrees or less, variation of in-plane retardation is 1 nm, photoelastic coefficient of thermoplastic resin of optically anisotropic layer (A) Is 6 × 10 ⁻¹² Pa ⁻¹ and the amount of residual volatile components in the optically anisotropic layer (A) is 0.01% or less. Therefore, when the optical laminate of the present invention is used for a liquid crystal display device and the display performance is confirmed, a good display can be confirmed not only from the front direction but also from an oblique direction within 40 ° up and down, left and right. The display characteristics are also good, there is no luminance unevenness, and the display characteristics are good for a long time. When viewed in a range exceeding 40 °, there is a slight inversion of gradation.
On the other hand, the optical laminate of Comparative Example 1 has a slow axis only in the optically anisotropic layer (A), Re ₄₀ / Re ₀ = 0.903, and the variation of the slow axis is ± 0.2 degrees or less, In-plane retardation variation is 25 nm, the photoelastic coefficient of the thermoplastic resin of the optically anisotropic layer (A) is 3 × 10 ⁻¹² Pa ⁻¹ , and the residual volatile component amount of the optically anisotropic layer (A) is 0 .01% or less. Therefore, when the optical laminate is used in a liquid crystal display device and the display performance is confirmed, there is no change over time in the aging test, but even when the display screen is viewed from the front, it is viewed from an oblique direction within 40 ° up and down and left and right. Even in this case, display unevenness is observed, and display failure occurs when viewed obliquely.
The optical laminated body of Comparative Example 2 is laminated so that the crossing angle between the optically anisotropic layer (A) and the optically anisotropic layer (B) is 0 degree, and Re ₄₀ / Re ₀ = 0. 907, variation of slow axis is ± 0.2 degrees or less, variation of in-plane retardation is 2 nm, photoelastic coefficient of thermoplastic resin of optically anisotropic layer (A) is 6 × 10 ⁻¹² Pa ⁻¹ , The amount of residual volatile components in the optically anisotropic layer (A) is 0.01% or less. Therefore, when the display performance is confirmed by using the optical laminate for a liquid crystal display device, the result of the time-lapse test is good, but the result of the viewing angle characteristic is poor.
The optical laminated body of Comparative Example 3 is laminated so that the crossing angle between the optically anisotropic layer (A) and the optically anisotropic layer (B) is 90 degrees, and Re ₄₀ / Re ₀ = 0. 885, variation of slow axis is ± 1.2 degrees or less, variation of in-plane retardation is 25 nm, photoelastic coefficient of thermoplastic resin of optically anisotropic layer (A) is 70 × 10 ⁻¹² Pa ⁻¹ , The amount of residual volatile components in the optically anisotropic layer (A) is 0.01% or less. For this reason, when the display performance is confirmed using the liquid crystal display device, both the viewing angle characteristics and the results of the aging test are poor.
The optical laminated body of Comparative Example 4 is laminated so that the crossing angle between the optically anisotropic layer (A) and the optically anisotropic layer (B) is 90 degrees, and Re ₄₀ / Re ₀ = 0. 891, the variation of the slow axis is ± 1.1 degrees or less, the variation of the in-plane retardation is 3 nm, the photoelastic coefficient of the thermoplastic resin of the optically anisotropic layer (A) is 6 × 10 ⁻¹² Pa ⁻¹ , The amount of residual volatile components in the optically anisotropic layer (A) is 0.3%. For this reason, when the display performance is confirmed using the liquid crystal display device, both the viewing angle characteristics and the results of the aging test are poor.

Claims (8)

An optical laminate (C) having a first optical anisotropic layer (A) containing a thermoplastic resin and a second optical anisotropic layer (B) containing a lyotropic liquid crystal molecule,
(B) The lyotropic liquid crystal molecules of the layer are aligned in a specific direction substantially perpendicular to the substrate surface by shearing, and (A) the in-plane slow axis of the layer and (B) the in-plane of the layer The slow axis is laminated substantially in parallel,
The in-plane retardation measured from the normal direction of the optical laminate (C) with light having a wavelength of 550 nm is Re ₀ , and the normal of the optical laminate (C) is irradiated with light having a wavelength of 550 nm from the normal to the in-plane slow axis direction. An optical laminated body satisfying 0.93 ≦ Re ₄₀ / Re ₀ ≦ 1.07, where Re ₄₀ is a retardation measured from a direction inclined by 40 °.   2. The optical laminate according to claim 1, wherein a variation of an in-plane slow axis of the optical laminate (C) is within ± 3 °. 3. The optical laminate according to claim 1, wherein an absolute value of a photoelastic coefficient of the thermoplastic resin of the (A) layer is 10 × 10 ⁻¹² Pa ⁻¹ or less. The optically laminated body according to any one of claims 1 to 3, wherein the lyotropic liquid crystal molecule is represented by the following (Chemical Formula 1) or (Chemical Formula 2).

The optical layered product according to any one of claims 1 to 4, wherein the layer (A) contains a norbornene polymer. Content of the residual volatile component of the said (A) layer is 0.1 weight% or less, The optical laminated body as described in any one of Claims 1-5 characterized by the above-mentioned. The polarizing plate which consists of a laminated body of the optical laminated body of any one of Claims 1-6 , and a polarizing film. IPS liquid crystal display device of the optical laminate formed by arranging on at least one side of the liquid crystal cell according to any one of claims 1-6.