JP4419606B2 - Optical laminated body, optical element, and liquid crystal display device - Google Patents

Description

  The present invention relates to an optical laminate that is easy to manufacture, excellent in viewing angle characteristics and display performance, and free from luminance unevenness and color unevenness, an optical element using the optical laminate, and a liquid crystal display device including the optical laminate.

Conventionally, the STN method has been widely used as a liquid crystal display. However, since the drive principle is relatively simple, it is generally used for products that place importance on low cost. However, in this method, since the coloring phenomenon derived from the wavelength dependence of the birefringence of the liquid crystal becomes obvious, various improvements have been made. Among them, an optical compensation method (film compensation method) using a retardation film is widely used as a simple method.
However, in this film compensation system, the biggest drawback is that the viewing angle is narrow. This is because the apparent optical path length of the film increases when the display is viewed from an oblique direction. For this reason, various methods of orientation treatment that increase the refractive index in the thickness direction of the retardation film have been studied.

  Patent Document 1 discloses a manufacturing method in which a film in which molecules are oriented in the normal direction of the film surface is stretched. Here, as a means for obtaining a normal direction oriented film, a rod rod obtained by extruding a molten resin from a nozzle is actually made and cut into a plate shape.

  Patent Document 2 discloses a laminate of a transparent film having a refractive index in the thickness direction larger than that of a refractive index in the plane direction and a retardation film made of a transparent stretched film. Here, as a means for increasing the refractive index in the thickness direction, in practice, an operation of applying a DC electric field is performed during the film forming process.

  Furthermore, Patent Document 3 discloses a production method in which a shrinkage force in a direction perpendicular to the stretching direction is applied by applying a heat stretching treatment after bonding a heat-shrinkable film to the surface of the film. And the retardation film which satisfy | fills 0 <(nx-nz) / (nx-ny) <1 is obtained using at least one retardation film produced by this method.

  In addition, Patent Document 4 discloses a laminate of at least one transparent film having negative intrinsic birefringence substantially having an optical axis in the normal direction and a transparent stretched film having positive intrinsic birefringence. There is disclosed a liquid crystal display device comprising: And as a transparent film which has the said negative intrinsic birefringence, what laminated | stacked the biaxially stretched film or the uniaxially stretched film is mentioned.

JP-A-2-160204 Japanese Patent Laid-Open No. 3-85519 JP-A-5-157911 JP-A-2-256603

  However, the method described in Patent Document 1 has a problem in that variations in phase difference, luminance unevenness, and color unevenness are not sufficiently reduced, and manufacturing efficiency is inferior. Also, with this method, it is difficult to obtain a large format that can be applied to a large liquid crystal screen such as a high-definition television.

  In addition, in the method described in Patent Document 2, particularly when a wide film is manufactured, it is considered that the equipment becomes so large, and if the electric field is applied too much, the film may be damaged, and the productivity is low. There's a problem.

  Furthermore, in the method described in Patent Document 3, it is necessary to precisely control the ratio between stretching and shrinkage, which complicates the manufacturing process and has the problem of low productivity.

Furthermore, the method described in Patent Document 4 is a method in which, when a biaxially stretched film or a uniaxially stretched film is used as a transparent film having negative intrinsic birefringence, the retardation is easily controlled and the productivity is high. It is believed that there is. However, in order to express the target phase difference, in reality, the strength of the material is insufficient, so that it is easy to break at the time of stretching. It is difficult to express, and it is considered that phase difference unevenness is likely to occur, which is not a realistic method. In addition, the film itself is difficult to make with a long body, and there is a problem that defects such as variations among individuals are likely to occur.
In addition, the retardation film is often used after being cut and bonded to a polarizing plate. In particular, the retardation film described in Patent Document 4 is easily chipped at the time of cutting, and thus is bonded to the polarizing plate. There is a problem that it is easy to tear.

  Therefore, the object of the present invention is that there are no problems such as tearing at the time of cutting or bonding with a polarizing plate, adjustment of phase difference characteristics is easy, and viewing angle characteristics and display performance are superior to conventional ones. Another object of the present invention is to provide an optical laminate having no luminance unevenness or color unevenness, an optical element obtained by using the optical laminate, and a liquid crystal display device including the optical laminate.

  As a result of intensive studies to solve the above problems, the present inventors laminated a layer containing a transparent resin on at least one side of a layer containing a resin having a negative intrinsic birefringence value. The above-mentioned problems are caused by laminating a roll wound body of an optical laminate formed by uniaxially stretching a laminate and a roll wound body of a uniaxially stretched film containing a transparent resin in a specific direction. The inventors have found that the problem can be solved, and have further advanced the research based on this finding, and have completed the present invention.

Thus, according to the present invention,
(1) A layer made of a transparent resin having a glass transition temperature lower than the glass transition temperature of a resin having a negative intrinsic birefringence value is laminated on at least one surface of the layer made of a resin having a negative intrinsic birefringence value. A roll roll of the optical laminate (A) formed by uniaxially stretching the laminate and a roll roll of the uniaxially stretched film (B) made of a transparent resin are respectively drawn out, and the optical laminate (A), A roll-shaped optical laminate that is laminated by a roll-to-roll method so that the crossing angle in the stretching direction of each uniaxially stretched film (B) is 90 ° ± 10 °, and satisfies the following [1] and [2] (C),
[1] 0 <(nx−nz) / (nx−ny) <1
[2] The variation of the front retardation Re represented by (nx−ny) × d is within ± 10 nm.
(In the above [1] and [2], d is the thickness (nm) of the optical laminate (C ), and nz is the refractive index in the thickness direction of the optical laminate (C) measured with light having a wavelength of 550 nm ( -), Nx is the refractive index (-) in the slow axis direction in the plane of the optical laminate (C) measured with light having a wavelength of 550 nm, and ny is the surface of the optical laminate (C) measured with light having a wavelength of 550 nm. The refractive index (−) in the direction perpendicular to the plane of the slow axis direction of
(2) In the optical laminate (A), Re (n) represents the in-plane retardation of the layer made of a resin having a negative intrinsic birefringence value, and Re (t) represents the in-plane retardation of the layer made of a transparent resin. The roll-shaped optical laminate (C) according to (1), wherein Re (n)> Re (t ) ;
(3) The roll-shaped optical laminate (C) according to (1) or (2), wherein the variation of the slow axis in the in-plane direction of the optical laminate (C) is within ± 5 °;
(4) The optical laminate (C) according to any one of (1) to (3), wherein the tear strength measured in accordance with JIS K7128-1 is 2 N / mm or more;
(5) When the glass transition temperature of the resin having a negative intrinsic birefringence value is Tg ₁ , the stretching temperature of uniaxial stretching of the laminate is (Tg ₁ −10) ° C. to (Tg ₁ +20) ° C. ( 1) The optical laminate (C) according to any one of (4);
(6) The optical laminate (C) according to any one of (1) to (5), wherein the intrinsic birefringence value of the transparent resin of the optical laminate (A) is positive;
(7) The optical laminate (C) according to any one of (1) to (6), wherein the laminate is formed by coextrusion;
(8) The optical laminate (A) according to any one of (1) to (7), wherein a layer made of a transparent resin is laminated on both sides of a layer made of a resin having a negative intrinsic birefringence value. Optical laminate (C);
(9) The optical laminate (C) according to (8), wherein the thickness of the transparent resin layer laminated on both surfaces of the resin layer having a negative intrinsic birefringence value is equal;
(10) Any of (1) to (9), wherein the optical laminate (A) and the uniaxially stretched film (B) are laminated so that the crossing angle of each slow axis is 0 ° ± 10 °. The optical laminate (C) according to 1;
( 11 ) A roll-shaped optical element comprising a laminate of the optical laminate (C) according to any one of (1) to ( 10 ) and a roll-like rolled product of a polarizing plate ;
(12 ) A liquid crystal display device comprising a cut-out optical laminate (C) according to any one of (1) to ( 10 ) provided on at least one side of a liquid crystal cell;
(13) A layer made of a transparent resin having a glass transition temperature lower than the glass transition temperature of a resin having a negative intrinsic birefringence value is laminated on at least one surface of the layer made of a resin having a negative intrinsic birefringence value. A roll roll of the optical laminate (A) formed by uniaxially stretching the laminate and a roll roll of the uniaxially stretched film (B) made of a transparent resin are respectively drawn out, and the optical laminate (A), A roll-shaped optical laminate (1) and (2) satisfying the following [1] and [2] by laminating by roll-to-roll method so that the crossing angle of each uniaxially stretched film (B) is 90 ° ± 10 °. A process for producing an optical laminate (C) for producing C),
[1] 0 <(nx−nz) / (nx−ny) <1
[2] The variation of the front retardation Re represented by (nx−ny) × d is within ± 10 nm.
(In the above [1] and [2], d is the thickness (nm) of the optical laminate (C), and nz is the refractive index in the thickness direction of the optical laminate (C) measured with light having a wavelength of 550 nm ( -), Nx is the refractive index (-) in the slow axis direction in the plane of the optical laminate (C) measured with light having a wavelength of 550 nm, and ny is the surface of the optical laminate (C) measured with light having a wavelength of 550 nm. The refractive index (−) in the direction perpendicular to the plane of the slow axis direction of
as well as,
(14) When the glass transition temperature of the resin having a negative intrinsic birefringence value is Tg ₁ , the stretching temperature for uniaxially stretching the laminate is (Tg ₁ -10) ° C. to (Tg ₁ +20) ° C. ( 13) The manufacturing method of the optical laminated body (C) of description;
Are provided respectively.

  The optical layered body of the present invention has no problems such as tearing when bonded to the polarizing plate (good production efficiency), easy control of the phase difference, and little variation in the phase difference, As a phase difference plate that can be highly compensated, has no brightness unevenness and color unevenness, and has excellent viewing angle characteristics, it can be widely applied to devices such as liquid crystal display devices and organic EL display devices.

  The optical laminate (C) of the present invention is an optical laminate obtained by uniaxially stretching a laminate obtained by laminating a layer made of a transparent resin on at least one side of a layer made of a resin having a negative intrinsic birefringence value ( The roll roll of A) and the roll roll of the uniaxially stretched film (B) made of a transparent resin are drawn out, and the optical laminate (A) and the stretch direction of the uniaxially stretched film (B) cross each other. It is laminated by a roll-to-roll method so that the angle is 90 ° ± 10 °.

  In the present invention, the roll wound body or the roll shape means one having a length of at least about 5 times the width direction of the film or laminate, preferably having a length of 10 times or more. Specifically, it has a length that is wound or stored or transported in a roll shape.

  The resin having a negative intrinsic birefringence value used in the optical layered body (A) of the present invention means that when light is incident on a layer in which molecules are aligned in a uniaxial order, the refractive index of light in the alignment direction is This is smaller than the refractive index of light in the direction orthogonal to the alignment direction.

  Examples of the resin having a negative intrinsic birefringence used in the optical laminate (A) include discotic liquid crystal polymers, vinyl aromatic polymers, polyacrylonitrile polymers, polymethyl methacrylate polymers, and cellulose ester polymers. And multi-component (binary, ternary, etc.) copolymers thereof. These can be used alone or in combination of two or more.

  Among these, at least one selected from vinyl aromatic polymers, polyacrylonitrile polymers, and polymethyl methacrylate polymers is preferable. Of these, vinyl aromatic polymers are more preferable from the viewpoint of high birefringence.

The vinyl aromatic polymer refers to a polymer of a vinyl aromatic monomer or a copolymer of a monomer copolymerizable with a vinyl aromatic monomer.
Examples of the vinyl aromatic monomer include styrene; styrene derivatives such as 4-methylstyrene, 4-chlorostyrene, 3-methylstyrene, 4-methoxystyrene, 4-tert-butoxystyrene, and α-methylstyrene; It is done. These may be used alone or in combination of two or more.
Monomers copolymerizable with vinyl aromatic monomers include olefins such as propylene and butene; α, β-ethylenically unsaturated nitrile monomers such as acrylonitrile; acrylic acid, methacrylic acid, maleic anhydride, etc. Α, β-ethylenically unsaturated carboxylic acid; acrylic acid ester, methacrylic acid ester; maleimide; vinyl acetate; vinyl chloride;
Among vinyl aromatic polymers, a copolymer of styrene or a styrene derivative and maleic anhydride is preferable from the viewpoint of high heat resistance.

  In the present invention, the thickness of the layer containing a resin having a negative intrinsic birefringence value as a main component is not particularly limited, but is usually 5 to 400 μm, preferably 15 to 250 μm.

  In the present invention, the glass transition temperature of the resin having a negative intrinsic birefringence value used in the optical laminate (A) is preferably 90 ° C. or higher, more preferably 100 ° C. or higher, from the viewpoint of excellent heat resistance during use. is there.

  The transparent resin used in the optical layered body (A) used in the present invention is not particularly limited as long as it has a thickness of 1 mm and a total light transmittance of 80% or more. An acetate resin such as triacetyl cellulose, polyester Resin, polyethersulfone resin, polycarbonate resin, chain polyolefin resin, polymer resin having an alicyclic structure, acrylic resin, polyvinyl alcohol resin, polyvinyl chloride resin, etc. A chain polyolefin-based resin or a polymer resin having an alicyclic structure is preferable, and a polymer resin having an alicyclic structure is particularly preferable from the viewpoints of transparency, low hygroscopicity, dimensional stability, lightness, and the like.

  The polymer resin having an alicyclic structure has an alicyclic structure in the main chain and / or side chain, and contains an alicyclic structure in the main chain from the viewpoint of mechanical strength, heat resistance and the like. Is preferred.

  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 is preferably 30% by weight or more. More preferably, it is 50% by weight or more, particularly preferably 70% by weight or more, and most 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.

Specifically, the polymer resin having an alicyclic structure includes (1) a norbornene polymer, (2) a monocyclic olefin polymer, (3) a cyclic conjugated diene polymer, and (4) vinyl. Examples thereof include alicyclic hydrocarbon polymers and hydrides thereof. Among these, norbornene-based polymers are more preferable from the viewpoints of transparency and moldability.
Specific examples of the norbornene-based polymer include ring-opening polymers of norbornene-based monomers, ring-opening copolymers of norbornene-based monomers and other monomers capable of ring-opening copolymerization, hydrides thereof, and norbornene-based monomers. And addition copolymers with other monomers copolymerizable with norbornene monomers. Among these, from the viewpoint of transparency, a ring-opening (co) polymer hydride of a norbornene-based monomer is most preferable.
The polymer having the alicyclic structure is selected from known polymers disclosed in, for example, JP-A No. 2002-321302.

Among norbornene polymers suitably used as the transparent resin of the optical layered body of the present invention, X: bicyclo [3.3.0] octane-2,4-diyl-ethylene structure and Y: It has a tricyclo [4.3.0.1 ^2,5 ] decane-7,9-diyl-ethylene structure, and the content of these repeating units is 90% by weight with respect to the entire repeating units of the norbornene polymer. % And the ratio of the content ratio of X and the content ratio of Y is preferably 100: 0 to 40:60 in terms of a weight ratio of X: Y. By using such a resin, it is possible to obtain an optical laminate that has no dimensional change in the long term and is excellent in stability of optical characteristics.

Examples of the monomer having the X structure as a repeating unit as a polymer include norbornene monomers having a structure in which a 5-membered ring is bonded to a norbornene ring. More specifically, tricyclo [4.3.0.1 ^2,5] deca-3,7-diene (trivial name: dicyclopentadiene) and their derivatives (those having a substituent on the ring), 7,8-tricyclo [4.3.0.1 ^{0, 5} ] Dec-3-ene (common name: methanotetrahydrofluorene) and its derivatives.
Moreover, as a monomer which has a structure of Y as a repeating unit as a polymer, tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] deca-3,7-diene (common name: tetracyclododecene) and derivatives thereof (those having a substituent in the ring).

  As a means for obtaining such a norbornene polymer, specifically, a) a monomer that can have the X structure as a repeating unit as a polymer, and a Y structure that can have the repeating structure as a polymer. Polymerization by controlling the copolymerization ratio with the monomer and, if necessary, hydrogenating unsaturated bonds in the polymer, b) repeating the polymer having the X structure as a repeating unit and the Y structure The method of controlling by the blend ratio with the polymer which has as a unit is mentioned.

  In the present invention, the molecular weight of the transparent resin is a polyisoprene measured by gel permeation chromatography (hereinafter abbreviated as “GPC”) using cyclohexane (toluene when the polymer resin is not dissolved) as a solvent. The weight average molecular weight (Mw) in terms of polystyrene is usually 5,000 to 100,000, preferably 8,000 to 80,000, more preferably 10,000 to 50,000. When the weight average molecular weight is in such a range, the mechanical strength and moldability of the optical laminate are highly balanced, which is preferable.

  In the present invention, the molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the transparent resin is not particularly limited, but is usually 1.0 to 10.0, preferably 1.0 to 4.0. Preferably it is the range of 1.2-3.5.

  The polymer resin having an alicyclic structure suitably used in the present invention has a content of a resin component having a molecular weight of 2,000 or less (that is, an oligomer component) of 5% by weight or less, preferably 3% by weight or less, more preferably Is 2% by weight or less. When the amount of the oligomer component is large, when the resin laminate is stretched, fine irregularities are generated on the surface or thickness unevenness occurs, resulting in poor surface accuracy.

  In order to reduce the amount of the oligomer component, the selection of the polymerization catalyst and the hydrogenation catalyst, the reaction conditions such as polymerization and hydrogenation, the temperature conditions in the step of pelletizing the resin as a molding material, etc. may be optimized. . The amount of the oligomer component can be measured by gel permeation chromatography using cyclohexane (toluene if the polymer resin does not dissolve).

  The thickness of the layer made of a transparent resin used in the optical layered body (A) used in the present invention is usually 5 to 250 μm, preferably 15 to 150 μm.

  A layer made of a resin having a negative intrinsic birefringence value and / or a layer made of a transparent resin used for the optical laminate (A) used in the present invention is a resin having a negative intrinsic birefringence value and a transparent resin, respectively. The resin consists of, as necessary, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, an antistatic agent, a dispersant, a chlorine scavenger, a flame retardant, a crystallization nucleating agent, Antiblocking agent, antifogging agent, release agent, pigment, organic or inorganic filler, neutralizing agent, lubricant, decomposition agent, metal deactivator, antifouling agent, antibacterial agent and other resins, thermoplastic elastomer Known additives such as can be added within a range not impairing the effects of the present invention. The addition amount of these additives is usually 0 to 5 parts by weight, preferably 0 to 3 parts by weight with respect to 100 parts by weight of the resin having a negative intrinsic birefringence value or a transparent resin.

In the optical laminate (A) used in the present invention, Re (n) represents the in-plane retardation of the layer made of a resin having a negative intrinsic birefringence, and Re (t) ), It is preferable that Re (n)> Re (t). Further, Re (t) <20 nm is preferable, and Re (t) <10 nm is more preferable.
In the optical layered body (A), when the in-plane retardation of each layer satisfies the above relationship, the slow axis of the optical layered body (A) can be set in a direction orthogonal to the stretching direction.
In the case where the optical laminate (A) is composed of a resin layer having a negative intrinsic birefringence or a transparent resin layer, each of which is composed of a plurality of layers, the Re (n) and Re (t ) Is the sum of the in-plane retardation of each of the multiple layers.
The in-plane retardation Re can be calculated by (nx−ny) × d. nx is the refractive index (−) in the slow axis direction in the plane of each layer measured with light having a wavelength of 550 nm, and ny is the direction orthogonal in the plane of the slow axis direction in the plane of each layer measured with light having a wavelength of 550 nm. The refractive index (−) and d of each layer are the thickness (nm) of each layer.

In the present invention, the glass transition temperature Tg ₂ of the transparent resin used for the optical laminate (A) is preferably lower than the glass transition temperature Tg ₁ of the resin having a negative intrinsic birefringence value, and is preferably 10 ° C. or lower. More preferably, it is more preferably 20 ° C. or lower. When Tg ₂ is equal to or greater than Tg ₁ , particularly when the intrinsic birefringence value of the transparent resin is positive, Re (n)> Re between the retardations Re (n) and Re (t). The relationship (t) cannot be satisfied. And it becomes impossible to make the slow axis of an optical laminated body (A) into the direction orthogonal to an extending | stretching direction.

  The optical laminate (A) used in the present invention is made of a transparent resin on both sides of a layer made of a resin having a negative intrinsic birefringence value from the viewpoint of preventing warpage due to moisture absorption, temperature change, or change with time. In this case, the thicknesses of the two layers of transparent resin are preferably substantially equal. Moreover, when laminating | stacking the layer which consists of transparent resin only on one side, there is no restriction | limiting in the number of layers to laminate | stack, how many layers may be laminated | stacked, but it is usually 1 layer.

  In the optical layered body (A) used in the present invention, an adhesive layer may be provided between a layer made of a resin having a negative intrinsic birefringence value and a layer made of a transparent resin.

The adhesive layer can be formed from a material having an affinity for both a resin having a negative intrinsic birefringence value used for the optical laminate (A) and a transparent resin. For example, ethylene- (meth) acrylate copolymer such as ethylene- (meth) acrylate methyl copolymer, ethylene- (meth) ethyl acrylate copolymer; ethylene-vinyl acetate copolymer, ethylene-styrene An ethylene copolymer such as a copolymer may be mentioned. In addition, modified products obtained by modifying these copolymers by oxidation, saponification, chlorination, chlorosulfonation or the like can also be used. In the present invention, when a modified ethylene-based copolymer is used, the handling property at the time of forming the laminated structure and the heat resistance deterioration property of the adhesive force can be improved.
The thickness of the adhesive layer is preferably 1 to 50 μm, more preferably 2 to 30 μm.

In the optical layered body (A) used in the present invention, when the adhesive layer is included, the glass transition temperature or softening point Tg ₃ of the adhesive is preferably lower than Tg ₁ and Tg ₂ , and Tg ₁ it is more preferred and less 20 ° C. or higher than Tg _2.

  The method for producing the optical laminate (A) used in the present invention is not particularly limited, but a layer made of a transparent resin is laminated on at least one side of a layer made of a resin having a negative intrinsic birefringence value. A stretched laminate (a) is obtained, which is then uniaxially stretched.

Examples of methods for obtaining the unstretched laminate (a) include coextrusion T-die method, coextrusion inflation method, coextrusion molding method such as coextrusion lamination method, film lamination molding method such as dry lamination, and base resin film For example, a known method such as a coating molding method in which a resin solution is coated can be appropriately used. Among these, a molding method by coextrusion is preferable from the viewpoints of production efficiency and that volatile components such as a solvent do not remain in the film.
The extrusion temperature can be appropriately selected according to the type of resin having a negative intrinsic birefringence value, a transparent resin, and an adhesive used as necessary.

  The method for uniaxially stretching the unstretched laminate (a) is not particularly limited, and conventionally known methods 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.

The stretching temperature of the unstretched laminate (a) is from (Tg ₁ -10) ° C. to (Tg), where Tg ₁ is the glass transition temperature of the resin having a negative intrinsic birefringence value used in the optical laminate (A). ₁ + 20) ° C. is preferable, and a range of (Tg ₁ −5) ° C. to (Tg ₁ +15) ° C. is more preferable.
In the optical laminate (A), the glass transition temperature Tg ₂ of the transparent resin used is lower than the glass transition temperature Tg ₁ of the resin having a negative intrinsic birefringence value, and the stretching temperature of the unstretched laminate (a) Between the in-plane retardation Re (n) of the layer made of a resin having a negative intrinsic birefringence and the in-plane retardation Re (t) of a layer made of a transparent resin. The relationship of (n)> Re (t) can be satisfied, whereby the viewing angle characteristics can be improved by adjusting the birefringence of each layer in accordance with the characteristics of the liquid crystal cell.

  The draw ratio of the unstretched laminate (a) is usually 1.1 to 30 times, preferably 1.3 to 10 times. If the draw ratio is out of the above range, the orientation may be insufficient, the refractive index anisotropy, and thus the retardation may be insufficiently developed, or the laminate may be broken.

The content of the residual volatile component in the optical laminate (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 during use, causing a dimensional change in the optical laminate (A) and generating internal stress. The phase difference may be uneven. Therefore, when the content of the volatile component of the optical layered body (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 time is excellent.
The volatile component is a substance having a molecular weight of 200 or less contained in a trace amount in the optical laminate (A), and examples thereof include a residual monomer and a solvent. The content of the volatile component can be quantified by analyzing the optical layered product (A) by gas chromatography as the sum of substances having a molecular weight of 200 or less contained in the optical layered product (A).

As transparent resin used in order to obtain the uniaxially stretched film (B) used in this invention, the same thing as transparent resin used for an optical laminated body (A) can be mentioned. Among them, a polymer resin or a chain olefin polymer having an alicyclic structure is preferable, and a polymer resin having an alicyclic structure is particularly preferable from the viewpoint of transparency, low hygroscopicity, dimensional stability, lightness, and the like. preferable.
In addition, the uniaxially stretched film (B) is made of a transparent resin, and if necessary, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, an antistatic agent, a dispersant, a chlorine scavenger. , 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 within a range that does not impair the effects of the present invention. The addition amount of these additives is usually 0 to 5 parts by weight, preferably 0 to 3 parts by weight with respect to 100 parts by weight of the transparent resin.

The uniaxially stretched film (B) used in the present invention is obtained by uniaxially stretching an unstretched film (b) containing a transparent resin. The method for obtaining the unstretched film (b) is not particularly limited, and a known molding method can be employed. For example, both of the hot melt molding method and the solution casting method can be employed, but it is preferable to use the hot melt molding method from the viewpoint of manufacturing efficiency and not leaving volatile components such as a solvent in the film. . More specifically, the hot melt molding method can be classified into a melt extrusion molding method, a press molding method, an inflation method, an injection molding method, a blow molding method, and the like. Among these, in order to obtain a stretched film having excellent mechanical strength and surface accuracy, it is preferable to use a melt extrusion molding method.
The extrusion temperature can be appropriately selected according to the glass transition temperature of the transparent resin.

  The method for uniaxially stretching the unstretched film (b) is not particularly limited, and conventionally known methods can be applied. About the extending | stretching method, the same method as the method demonstrated in the column of an optical laminated body (A) is mentioned.

  The stretching temperature when stretching the unstretched film (b) is preferably between (Tg-30 ° C) and (Tg + 60 ° C), more preferably (Tg-10 ° C), where Tg is the glass transition temperature of the transparent resin. ) To (Tg + 50 ° C.). Moreover, a draw ratio is 1.01-30 times normally, Preferably it is 1.01-10 times, More preferably, it is 1.01-5 times. The stretching conditions of the unstretched film (b) are appropriately adjusted so that the optical laminate (C) obtained by laminating the optical laminate (A) and the uniaxially stretched film (B) has a desired retardation. That's fine.

  The optical laminate (C) of the present invention is laminated so that the crossing angle between the stretching axes of the optical laminate (A) and the uniaxially stretched film (B) is 90 ° ± 10 °, preferably 90 ° ± 5 °. To do.

  In the optical laminate (C) of the present invention, nx, ny, and nz of the entire optical laminate (C) satisfy the relationship 0 <(nx−nz) / (nx−ny) <1, 0.1 <(nx−nz) / (nx−ny) <0.9 is satisfied, and 0.3 <(nx−nz) / (nx−ny) <0.7 is satisfied. Is more preferable, and it is particularly preferable that (nx−nz) / (nx−ny) ≈0.5 is satisfied. By satisfying the relationship of 0.3 <(nx−nz) / (nx−ny) <0.7, nx, ny, nz of the entire optical laminate (C), the incident angle dependency of the retardation value can be reduced. By satisfying (nx−nz) / (nx−ny) ≈0.5, the incident angle dependency of the phase difference value is substantially eliminated, and the same phase difference value is obtained regardless of the angle from which light enters. Can be given.

  In the optical layered body (C) of the present invention, the variation of the front retardation Re represented by (nx−ny) × d is within 10 nm, preferably within 5 nm, and more preferably within 2 nm. By setting the variation of the front retardation Re within the above range, the display quality can be improved when used as a retardation film for a liquid crystal display device. Here, the variation of the front retardation Re is when the front retardation when the incident angle of light is 0 ° (the state where the incident light beam and the laminate surface of the present invention are orthogonal) is measured in the width direction of the optical laminate. It is the difference between the maximum value and the minimum value of the front retardation.

  In the optical laminate (C) of the present invention, the thickness of the optical laminate (C) is d (nm) and the refractive index in the thickness direction of the optical laminate (C) measured with light having a wavelength of 550 nm is nz (- ), The refractive index in the slow axis direction in the plane of the optical laminate (C) measured with light having a wavelength of 550 nm is nx (−), and the retardation in the plane of the optical laminate (C) measured with light having a wavelength of 550 nm is measured. When the refractive index in the direction orthogonal to the plane in the phase axis direction is ny (−), −100 nm <[{(nx + ny) / 2} −nz] × d <100 nm, preferably −30 nm <[{ (Nx + ny) / 2} −nz] × d <30 nm, and more preferably [{(nx + ny) / 2} −nz] × d = 0 nm.

In the optical laminate (C) of the present invention, the variation of the slow axis in the in-plane direction is preferably within ± 5 °, more preferably within ± 3 °, and within ± 1 °. Further preferred.
By setting the variation of the slow axis in the in-plane direction within the above range, when the optical laminate (C) of the present invention is used as a retardation film and bonded to a polarizing plate in a liquid crystal display device, color unevenness or A good liquid crystal display without color loss 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 optical layered body (C) of the present invention is formed by drawing out a roll wound body of the optical laminate (A) and a roll wound body of the uniaxially stretched film (B) and laminating them by a roll-to-roll method.
The roll-to-roll method refers to a method in which roll-rolled films are continuously bonded by applying an adhesive or a pressure-sensitive adhesive to the bonding surface as necessary.

In the optical laminate (C) of the present invention, the optical laminate (A) and the uniaxially stretched film (B) are laminated so that the crossing angles of the respective slow axes are 0 ° ± 10 °. Preferably there is.
By laminating so that the crossing angle of the slow axis is in the above range, (nx−nz) / (nx−ny) of the optical layered body (C) is efficiently made the most preferable value of 0.5. Can do. By setting the (nx−nz) / (nx−ny) to 0.5, the incident angle dependency of the phase difference value is substantially eliminated, and the same phase difference value is given no matter what angle the light enters. Can do.

  In the optical laminate (C) of the present invention, the tear strength measured according to JIS K7128-1 is preferably 2 N / mm or more, more preferably 2.5 N / mm or more. By doing so, the optical laminate (C) can be prevented from tearing when bonded to the polarizing plate, and the yield can be improved.

  Since the optical laminate (C) of the present invention can be easily manufactured and highly compensated for birefringence, a polarization separation layer is laminated on the optical laminate as a retardation plate excellent in viewing angle dependency. As a brightness enhancement film, it can be widely applied to display devices such as liquid crystal display devices and organic EL display devices.

The roll-shaped optical element of the present invention is composed of a laminate of the optical laminate (C) of the present invention and a roll wound body of a polarizing plate.
The basic structure of the polarizing plate used in the optical element of the present invention is a protective layer through an appropriate adhesive layer on one or both sides of a polarizer made of a polyvinyl alcohol polarizing film containing a dichroic substance. It consists of what attached the transparent protective film.
As a polarizer, for example, a film made of a suitable vinyl alcohol-based polymer according to the prior art such as polyvinyl alcohol or partially formalized polyvinyl alcohol, a dyeing treatment with a dichroic substance made of iodine or a dichroic dye, a stretching treatment In addition, an appropriate treatment such as a crosslinking treatment can be performed in an appropriate order and method, and an appropriate material that transmits 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 polarizer is generally 5 to 80 μm, but is not limited thereto.

An appropriate transparent film can be used as a protective film material to be a transparent protective layer provided on one side or both sides of the polarizer. Among them, a film made of a polymer excellent in transparency, mechanical strength, thermal stability, moisture shielding property, etc. is preferably used. The polymers include acetate resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, and polymer resins having an alicyclic structure. Acrylic resins and the like are mentioned. Among them, acetate resins or polymer resins having an alicyclic structure are preferable from the viewpoint of low birefringence, and viewpoints of transparency, low hygroscopicity, dimensional stability, lightness, etc. Therefore, a polymer resin having an alicyclic structure is particularly preferable.
The thickness of the transparent protective film is arbitrary, but is generally 500 μm or less, preferably 5 to 300 μm, particularly preferably 5 to 150 μm for the purpose of reducing the thickness of the polarizing plate.

Lamination | stacking with an optical laminated body (C) and a polarizing plate can be bonded together using appropriate adhesion means, such as an adhesive agent and an adhesive. Examples of the adhesive or pressure-sensitive adhesive include acrylic, silicone, polyester, polyurethane, polyether, rubber, and the like. Among these, an acrylic type is preferable from the viewpoint of heat resistance and transparency.
The optical laminate (C) and the polarizing plate are laminated so that the slow axis of the optical laminate (C) and the transmission axis of the polarizer are parallel or orthogonal to each other. Examples of the laminating method include a roll-to-roll method.
In the optical laminate (C) of the present invention, a layer made of a transparent resin in the optical laminate (C) of the present invention (this is a layer made of a transparent resin of the optical laminate (A), or a transparent layer). It means a uniaxially stretched film made of resin.) And can also serve as a transparent protective film of a polarizing plate to be laminated, and the thickness of the member can be reduced.
The thickness of the optical element of the present invention is usually 100 to 700 μm, preferably 200 to 600 μm.

The liquid crystal display device of the present invention includes a cut-out of the optical laminate (C) of the present invention on at least one side of the liquid crystal cell. As an aspect which equips the liquid crystal cell with the optical laminated body (C) of this invention, the optical laminated body (C) is arrange | positioned between a polarizing plate and a liquid crystal cell; An embodiment in which C) is arranged is exemplified. In an embodiment in which the optical laminate (C) is provided between the polarizing plate and the liquid crystal cell, the optical element of the present invention can be disposed in the liquid crystal cell. Since the optical laminated body and the optical element of the present invention are roll-shaped wound bodies, when they are incorporated into a liquid crystal display device, they are cut into an appropriate size.
The liquid crystal display device of the present invention is formed with a suitable structure according to the prior art, such as a transmissive type, a reflective type, or a transmissive / reflective type in which a polarizing plate is arranged on one or both sides of a liquid crystal cell. Can do. The liquid crystal modes used in the liquid crystal cell include TN (Twisted Nematic) type, STN (Super Twisted Nematic) type, HAN (Hybrid Alignment Nematic) type, VA (Vertical Alignment), MVA (Multi-type Inlet). Plane Switching) type, OCB (Optical Compensated Bend) type, and the like.

  Moreover, when providing a polarizing plate on both sides of a liquid crystal cell, the polarizing plate may be the same or different. Further, when forming a liquid crystal display device, for example, appropriate parts such as a brightness enhancement film, a prism array sheet, a lens array sheet, a light guide plate, a light diffusion plate, and a backlight are arranged in one or more layers at appropriate positions. be able to.

  In the liquid crystal display device of the present invention, a pressure-sensitive adhesive layer can be provided in order to bond the optical laminate of the present invention and the liquid crystal cell. The pressure-sensitive adhesive layer can be appropriately formed using a conventionally known pressure-sensitive adhesive such as acrylic. In particular, the moisture absorption rate is low in terms of prevention of foaming and peeling phenomena due to moisture absorption, deterioration of optical properties due to thermal expansion differences, prevention of warping of liquid crystal cells, and formation of liquid crystal display devices with high quality and durability. The pressure-sensitive adhesive layer is preferably low and excellent in heat resistance. Moreover, it can also be set as the adhesive layer etc. which contain microparticles | fine-particles and show light diffusibility.

  When the pressure-sensitive adhesive layer provided on the polarizing plate is exposed on the surface, it is preferable to temporarily cover with a separator for the purpose of preventing contamination until the pressure-sensitive adhesive layer is put to practical use. The separator is formed by, for example, a method in which a release coat with an appropriate release agent such as a silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide is provided on an appropriate thin leaf according to the above-described transparent protective film or the like. be able to.

  In addition, each layer, such as a polarizer, a transparent protective film, an optical layer, and an adhesive layer, which form the polarizing plate described above is, for example, a salicylic acid ester compound, a benzophenone compound, a benzotriazole compound, a cyanoacrylate compound, or a nickel complex salt system. It may be provided with ultraviolet absorbing ability by an appropriate method such as a method of treating with an ultraviolet absorber such as a compound.

The present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. Parts and% are based on weight unless otherwise specified.
Evaluation in the present invention is performed by the following method.
(1) Molecular weight Measured by gel permeation chromatography (GPC) using cyclohexane (toluene if the polymer resin is not dissolved) as a solvent to determine the weight average molecular weight (Mw) in terms of standard polyisoprene (2) Glass transition Temperature (Tg)
Measurement is performed using differential scanning calorimetry (DSC) based on JIS K7121.
(3) Thickness of the film or laminate The cross section of the film or laminate is observed and measured with an optical microscope. About a laminated body, it measures for every layer.
(4) Refractive index nz in the thickness direction measured with light with a wavelength of 550 nm, In-plane slow refractive index nx measured with light with a wavelength of 550 nm, In-plane slow axis measured with light with a wavelength of 550 nm Refractive index ny in the direction perpendicular to the direction in the plane, variation in front retardation, variation in slow axis and slow axis, and crossing angle of slow axis and its variation Automatic birefringence meter (manufactured by Oji Scientific Instruments, Measured using KOBRA-21). In addition, the dispersion | variation in front retardation Re measures front retardation Re by the 10 mm space | interval in the width direction of a film or a laminated body, and makes it the arithmetic average value of the measured value, and the representative value of front retardation Re. Then, the difference between the maximum value and the minimum value among the measured values is defined as the variation of the front retardation Re.
The dispersion of the slow axis and the crossing angle of the slow axis is determined by measuring the slow axis at 10 mm intervals in the width direction of the film or laminate, obtaining the arithmetic average value of the measured values, and measuring the average value. The variation.
(5) Residual Volatile Component Amount 200 mg of the optical laminated body is put into a sample container of a glass tube having an inner diameter of 4 mm from which moisture and organic substances adsorbed on the surface are completely removed. 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 measured as a residual volatile component.
(6) Tear strength Based on JIS K7128-1, the trouser tear method is used and the test speed is 200 mm / min. The tear direction is the longitudinal direction and the width direction.
(7) Tear evaluation Tear evaluation is performed according to the following procedures (i) to (vi).
(I) A roll-shaped optical laminated body (the laminated body itself if not in a roll form) is pulled out by 50 cm and cut parallel to the width direction. The cut optical laminate is not used for this evaluation.
(Ii) Pull out the roll-shaped optical laminate further by 50 cm, hold each end in the width direction by hand, and apply a tearing force at an angle of about 180 degrees in a direction perpendicular to the main surface of the optical laminate.
(Iii) After applying a tearing force, the state of the cross section in the width direction of the optical laminate is observed.
The operations (i) to (iii) are repeated five times.
(Iv) The roll-shaped optical laminate is pulled out 50 cm and cut in the width direction.
(V) Pull out the roll-shaped optical laminate by 100 cm, hold one end in the width direction of the drawn optical laminate and the end in the longitudinal direction including the one end by hand, and extend approximately in the direction perpendicular to the main surface of the optical laminate. Apply tearing force at an angle of 180 degrees.
(Vi) After applying the tearing force, the state of the cross section in the longitudinal direction of the optical laminate is observed.
The operations (v) to (vi) are repeated five times.
For samples that are not in roll form, prepare 10 samples of the laminated body, of which 5 are evaluated in (ii) and (iii), and the other 5 are evaluated in (v) and (vi). Do each.
When a tearing force is applied, the cross section of the laminated body is observed, and the case where the laminated body is torn is marked as x, and the case where the laminated body is not broken is marked as ◯.
(8) Display performance The optical element is cut into an appropriate size and placed on both sides (outgoing side and incident side) of the liquid crystal cell of the STN type liquid crystal display device, and the display characteristics are visually observed. Further, 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 40 ° in the vertical and horizontal directions in the dark room.
In addition, when arrange | positioning an optical element in a liquid crystal cell, it arrange | positions so that an optical laminated body may come to the liquid crystal cell side.

(Production Example 1) Production of polymer resin having alicyclic structure To 500 parts of dehydrated cyclohexane, 0.82 part of 1-hexene, 0.15 part of dibutyl ether, and 0.30 part of triisobutylaluminum were added under a nitrogen atmosphere. After mixing in a reactor at room temperature and maintaining at 45 ° C., tricyclo [4.3.0.1 ^2,5 ] deca-3,7-diene (dicyclopentadiene, hereinafter abbreviated as “DCP”). ) 170 parts, 8-ethylidene-tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -dodec-3-ene (ethylidenetetracyclododecene, hereinafter abbreviated as “ETD”) 30 parts norbornene monomer mixture and tungsten hexachloride (0.7% toluene solution) ) 40 parts was continuously added over 2 hours for polymerization. To the polymerization solution, 1.06 part of butyl glycidyl ether and 0.52 part of isopropyl alcohol were added to inactivate the polymerization catalyst, and the polymerization reaction was stopped.

  Next, 35 parts of cyclohexane is added to 100 parts of the reaction solution containing the obtained ring-opening polymer, and 5 parts of a nickel-alumina catalyst (manufactured by JGC Chemical Co., Ltd.) is added as a hydrogenation catalyst. The mixture was heated to 200 ° C. while being stirred and pressurized to 5 MPa, and then reacted for 4 hours to obtain a reaction solution containing 20% of a DCP / ETD ring-opening copolymer hydride.

  When the copolymerization ratio of each norbornene monomer in the obtained ring-opening copolymer hydride was calculated from the composition of residual norbornenes in the solution after polymerization (by gas chromatography method), DCP / It was almost equal to the charged composition at ETD = 85/15 (weight ratio). The norbornene-based polymer 1 had a weight average molecular weight (Mw) of 35,000, a molecular weight distribution of 2.1, and a content of a resin component having a molecular weight of 2,000 or less was 0.7% by weight. The hydrogenation rate was 99.9% and Tg was 105 ° C.

  After removing the hydrogenation catalyst by filtration, an antioxidant (trade name: Irganox 1010, manufactured by Ciba Specialty Chemicals) was added to the resulting solution and dissolved (the amount of the antioxidant added) 0.1 parts per 100 parts polymer).

  Subsequently, cyclohexane and other volatile components, which are solvents, are removed from the solution at a temperature of 270 ° C. and a pressure of 1 kPa or less by using a cylindrical concentrating dryer (manufactured by Hitachi, Ltd.). A hydrogenated DCP / ETD ring-opening copolymer (hereinafter abbreviated as “norbornene polymer 1”), which is an example of a polymer resin having a structure, was obtained.

(Production Example 2) Production of roll of optical laminate A1 A layer composed of norbornene polymer 1 obtained in Production Example 1, styrene-maleic acid copolymer (trade name “Nova Chemical Co., Ltd. B layer composed of “Daylark D332”, glass transition temperature 130 ° C., oligomer component content 3% by weight, and modified ethylene-vinyl acetate copolymer (trade name “Modic AP A543”, manufactured by Mitsubishi Chemical Co., Ltd., Vicat softening point) A layer (35 μm) -c layer (7 μm) -b layer (85 μm) -c layer (7 μm) -a layer (35 μm) unstretched laminate A having an adhesive layer (c layer) composed of 80 ° C. -1 rolls were obtained by coextrusion.
Next, the roll wound body of the unstretched laminate A-1 is subjected to transverse uniaxial stretching at a stretching temperature of 142 ° C., a stretching ratio of 2.7 times, and a stretching speed of 20 mm / min, using a tenter stretching machine. A roll roll of optical laminate A1 was obtained. The in-plane retardation Re (t) of the a layer of the roll roll of the obtained optical laminate A1 was 0 nm in total, and the in-plane retardation Re (n) of the b layer was 103 nm.

(Production Example 3) Production of roll roll of optical laminate A2 Layer a composed of norbornene polymer 1 obtained in Production Example 1, styrene-maleic acid copolymer (trade name “Nova Chemical Co., Ltd. B layer composed of “Daylark D332”, glass transition temperature 130 ° C., oligomer component content 3% by weight, and modified ethylene-vinyl acetate copolymer (trade name “Modic AP A543”, manufactured by Mitsubishi Chemical Co., Ltd., Vicat softening point) A layer (78 μm) -c layer (16 μm) -b layer (117 μm) -c layer (16 μm) -a layer (78 μm) unstretched laminate A having an adhesive layer (c layer) comprising 80 ° C. -2 rolls were obtained by coextrusion.
Next, the roll wound body of the unstretched laminate A-2 is subjected to longitudinal uniaxial stretching at a stretching temperature of 141 ° C., a stretching ratio of 1.5 times, and a stretching speed of 20 mm / min, using a longitudinal stretching machine. A roll roll of optical laminate A2 was obtained. The in-plane retardation Re (t) of the a layer of the roll roll of the obtained optical laminate A2 was 3 nm in total, and the in-plane retardation Re (n) of the b layer was 262 nm.

(Production Example 4) Production of roll of optical laminate A3 As a norbornene polymer, other norbornene polymer (manufactured by Nippon Zeon Co., Ltd., “ZEONOR1420”, glass transition temperature is 136 ° C.) is used. Co-extrusion molding was carried out in the same manner as in Production Example 2, and an unstretched laminate A-3 of a layer (35 μm) -c layer (7 μm) -b layer (140 μm) -c layer (7 μm) -a layer (35 μm) A roll of roll was obtained.
Next, the roll wound body of the unstretched laminate A-3 is subjected to longitudinal uniaxial stretching at a stretching temperature of 142 ° C., a stretching ratio of 1.3 times, and a stretching speed of 15 mm / min, using a tenter stretching machine. A roll roll of optical laminate A3 was obtained. The in-plane retardation Re (t) of the a layer of the roll roll of the obtained optical laminate A3 was 300 nm in total, and the in-plane retardation Re (n) of the b layer was 50 nm.

(Production Example 5) Production of roll roll of uniaxially stretched film B1 A hot air dryer in which air was circulated through pellets of a norbornene polymer (manufactured by Nippon Zeon Co., Ltd., “ZEONOR1420”, glass transition temperature: 136 ° C.). And dried at 100 ° C. for 4 hours. 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 115 μm film B-1 was obtained. This film B-1 was wound up into a roll and made into a roll.
The roll wound body of the uniaxially stretched film B1 was obtained by performing longitudinal uniaxial stretching of the roll wound body of the film B-1 at a stretching temperature of 140 ° C., a stretching ratio of 1.3 times, and a stretching speed of 20 mm / min. . The in-plane retardation Re of the uniaxially stretched film B1 was 270 nm.

(Production Example 6) Production of roll roll of uniaxially stretched film B2 Other production examples using other norbornene polymers (manufactured by Zeon Corporation, “ZEONOR1600”, glass transition temperature 163 ° C.) as norbornene polymers. In the same manner as in Example 5, a roll wound body of film B-2 having a thickness of 115 μm was obtained.
Next, the roll wound body of the film B-2 is subjected to transverse uniaxial stretching at a stretching temperature of 169 ° C., a stretching ratio of 1.3 times, and a stretching speed of 10 mm / min. Obtained. The in-plane retardation Re of the uniaxially stretched film B2 was 100 nm.

(Manufacture example 7) Manufacture of uniaxially stretched film B3 It melt | dissolved in the styrene-maleic acid copolymer 15 parts same as b layer in manufacture example 2, and 85 parts of methylene chlorides, and obtained the resin solution composition. This resin solution was placed on a surface-polished glass plate and cast into a width of about 300 mm and a length of 500 mm by a bar coater. This was dried as the first stage by raising the temperature from 25 ° C. to 90 ° C. over 30 minutes in an air reflux type oven together with the glass plate. After cooling to room temperature, a part of the sheet was cut out and the residual solvent concentration was measured and found to be 2.5% by weight. Next, as the second stage of drying, it is dried in an oven at 140 ° C. for 90 minutes, and after cooling to room temperature, the resin film is peeled off from the glass plate, the width of 10 mm is cut off, and a single-layer styrene-maleic acid copolymer is used. An unstretched film B-3 having a thickness of 500 μm was obtained. Then, this was subjected to longitudinal uniaxial stretching at a stretching temperature of 159 ° C., a stretching ratio of 2.7 times, and a stretching speed of 18 mm / min to obtain a uniaxially stretched film B3.
The in-plane retardation Re of the uniaxially stretched film B3 was 273 nm.

(Manufacture example 8) Manufacture of uniaxially stretched film B4 The pellet of the norbornene-type polymer (The Nippon Zeon company make, "ZEONOR1420", glass transition temperature is 136 degreeC) which is an example of the polymer which has an alicyclic structure, air It dried for 4 hours at 100 degreeC using the distribute | circulated hot air dryer. 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 120 μm film B-4 was obtained. This film B-4 was wound up into a roll to obtain a roll-shaped body.
The roll wound body of the uniaxially stretched film B4 was obtained by performing transverse uniaxial stretching of the roll wound body of the film B-4 at a stretching temperature of 142 ° C., a stretching ratio of 1.4 times, and a stretching speed of 20 mm / min. . The in-plane retardation Re of the uniaxially stretched film B4 was 107 nm.

(Example 1) Manufacture of roll-shaped optical laminated body C1 The roll wound body of optical laminated body A1 obtained by manufacture example 2 and the roll roll body of uniaxially stretched film B1 obtained by manufacture example 5 The rolls were laminated by a roll-to-roll method so that the respective stretching directions were orthogonal to obtain a roll-shaped optical laminate C1. The evaluation results of the obtained optical laminate C1 are shown in Table 1.

(Example 2) Manufacture of roll-shaped optical laminate C2 A roll roll of optical laminate A2 obtained in Production Example 3 and a roll roll of uniaxially stretched film B2 obtained in Production Example 6 The rolls were laminated by a roll-to-roll method so that the respective stretching directions were orthogonal to obtain a roll-shaped optical laminate C2. The evaluation results of the obtained optical laminate C2 are shown in Table 1.

(Comparative example 1) Manufacture of optical laminated body C3 The roll roll body of the uniaxially stretched film B4 obtained in the manufacture example 8, each uniaxially stretched film B3 obtained in the manufacture example 7 is cut into a sheet of 100 × 100 mm, An optical laminate C3 was obtained by aligning the respective longitudinal directions and laminating so that the stretching directions were orthogonal. The evaluation results of the obtained optical laminate C3 are shown in Table 1.

(Comparative example 2) Manufacture of optical laminated body C4 The roll winding body of optical laminated body A3 obtained in Production Example 4 and the uniaxially stretched film B1 obtained in Production Example 5 are parallel to each other. Thus, the roll-shaped optical laminate C4 was obtained by laminating by the roll-to-roll method. Table 1 shows the evaluation results of the obtained optical layered body C4.

(Example 3) Manufacture of roll-shaped optical element 1 Slow axis and roll-shaped polarizing plate (polarizing plate (manufactured by Sanlitz, HLC2-5618S, thickness) of roll-shaped optical laminate C1 obtained in Example 1 180 μm) was laminated by a roll-to-roll method to obtain a roll-shaped optical element 1. At this time, the angle formed by the slow axis of the optical laminate C1 and the absorption axis of the polarizing plate was 0 °. .
The display performance of the obtained roll-shaped optical element 1 was evaluated. As a result of the evaluation, 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.

(Example 4) Production of roll-shaped optical element 2 A roll-shaped optical element 2 was obtained in the same manner as in Example 3 except that the optical laminate C2 obtained in Example 2 was used as the roll-shaped optical laminate (C). Optical element 2 was obtained. At this time, the angle formed by the slow axis of the optical laminate C2 and the absorption axis of the polarizing plate was 90 °.
The display performance of the obtained roll-shaped optical element 2 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.

Comparative Example 3 Production of Optical Element 3 A roll-shaped polarizing plate was cut into a size of 100 × 100, and this was laminated with the optical laminate C3 obtained in Comparative Example 1 to obtain an optical element 3. . At this time, the angle formed by the slow axis of the optical laminate C3 and the absorption axis of the polarizing plate was 90 °.
The display performance of the obtained optical element 3 was evaluated. As a result of evaluation, there was display unevenness over the entire surface, and the color tone and gradation were not uniform. In addition, uneven brightness was also observed over the entire surface.

(Comparative Example 4) Manufacture of roll-shaped optical element 4 A roll-shaped optical element 4 was obtained in the same manner as in Example 3 except that the optical laminate C4 obtained in Comparative Example 2 was used as the roll-shaped optical laminate. Got. At this time, the angle formed by the slow axis of the optical laminate C4 and the absorption axis of the polarizing plate was 0 °.
The display performance of the obtained optical element 4 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.

From the results in Table 1, the following can be understood.
As shown in the examples, the optical laminate of the present invention has (nx−nz) / (nx−ny) = 0.5, the variation of the front retardation Re is 0.5 nm, and the optical laminate (A) And it laminates | stacks so that the crossing angle with the extending | stretching direction of a uniaxially stretched film (B) may be 90 degrees. Therefore, the tear strength is 2 N / mm or more in the longitudinal direction and the width direction, the variation in the crossing angle of the slow axes between the laminates is small, and no tear is generated even in the tear evaluation (Examples 1 and 2). ). Further, when an optical element is prepared using the optical laminate of the present invention and used for a liquid crystal display device to evaluate display performance, a good display is obtained not only in the front direction but also in an oblique direction within 40 ° in the vertical and horizontal directions. In-plane display characteristics are good, and there is no luminance unevenness (Examples 3 and 4).
On the other hand, the optical laminated body of Comparative Example 1 has (nx−nz) / (nx−ny) = 0.5, and the stretching axis of each of the optical laminated body (A) and the uniaxially stretched film (B) is 90 °. The variation of the front retardation Re is 25 nm. Therefore, the tear evaluation of the optical laminate (C) is good, but the variation in the crossing angle of the slow axes between the optical laminates (C) is large. Furthermore, as shown in Comparative Example 3, when an optical element is prepared using this optical laminate and used for a liquid crystal display device to evaluate display performance, display unevenness or luminance unevenness is observed on the entire surface. Or
In the optical laminated body of Comparative Example 2, the variation in the front retardation Re is 0.5 nm, but (nx−nz) / (nx−ny) = 1, and the optical laminated body (A) and the uniaxially stretched film ( B) It is laminated so that each stretching axis is 0 degree. Therefore, although the variation in the crossing angle of the slow axis between the optical laminates (C) is small, tearing occurs in the tear evaluation. Furthermore, as shown in Comparative Example 4, when an optical element is prepared using this optical laminate and used for a liquid crystal display device to evaluate display performance, display unevenness is not observed on the entire surface, but 40 ° in the vertical and horizontal directions. Display failure occurs when viewed from the diagonal direction.

Claims (14)

A laminate in which a layer made of a transparent resin having a glass transition temperature lower than the glass transition temperature of a resin having a negative intrinsic birefringence value is laminated on at least one surface of the layer made of a resin having a negative intrinsic birefringence value. A roll roll of the optical laminate (A) formed by uniaxial stretching and a roll roll of the uniaxial stretch film (B) made of a transparent resin are respectively drawn out, and the optical laminate (A) and the uniaxial stretch film are drawn. (B) A roll-shaped optical laminate (C) that is laminated by a roll-to-roll method so that the crossing angle in each stretching direction is 90 ° ± 10 ° and satisfies the following [1] and [2] .
[1] 0 <(nx−nz) / (nx−ny) <1
[2] The variation of the front retardation Re represented by (nx−ny) × d is within ± 10 nm.
(In the above [1] and [2], d is the thickness (nm) of the optical laminate (C ), and nz is the refractive index in the thickness direction of the optical laminate (C) measured with light having a wavelength of 550 nm ( -), Nx is the refractive index (-) in the slow axis direction in the plane of the optical laminate (C) measured with light having a wavelength of 550 nm, and ny is the surface of the optical laminate (C) measured with light having a wavelength of 550 nm. The refractive index (−) in the direction perpendicular to the plane of the slow axis direction is shown.) When the optical laminate (A) has Re (n) as the in-plane retardation of a layer made of a resin having a negative intrinsic birefringence value and Re (t) as the in-plane retardation of a layer made of a transparent resin. The roll-shaped optical laminate (C) according to claim 1, wherein Re (n)> Re (t ) . The roll-shaped optical laminate (C) according to claim 1 or 2, wherein the variation of the slow axis in the in-plane direction of the optical laminate (C) is within ± 5 °. The optical laminate (C) according to any one of claims 1 to 3, wherein the tear strength measured according to JIS K7128-1 is 2 N / mm or more. The glass transition temperature of a resin having a negative intrinsic birefringence value is expressed as Tg. ₁ The stretching temperature at which the laminate is uniaxially stretched is (Tg ₁ −10) ° C. to (Tg ₁ It is +20) degreeC. The optical laminated body (C) in any one of Claims 1-4. The optical laminate (C) according to any one of claims 1 to 5, wherein the intrinsic birefringence value of the transparent resin of the optical laminate (A) is positive. The optical laminate (C) according to any one of claims 1 to 6, wherein the laminate is formed by coextrusion. The optical laminate (C) according to any one of claims 1 to 7, wherein a layer made of a transparent resin is laminated on both sides of a layer made of a resin having a negative intrinsic birefringence value in the optical laminate (A). ). The optical laminate (C) according to claim 8, wherein the thickness of the layer made of transparent resin laminated on both surfaces of the layer made of resin having a negative intrinsic birefringence value is equal. The optical laminated body according to any one of claims 1 to 9, wherein the optical laminated body (A) and the uniaxially stretched film (B) are laminated so that the crossing angle of each slow axis is 0 ° ± 10 °. Body (C). The roll-shaped optical element which consists of a laminated body of the optical laminated body (C) of any one of Claims 1-10 , and the roll wound body of a polarizing plate. LCD those cut out optical laminate (C) as claimed in any one of claims 1 to 10 provided on at least one side of the liquid crystal cell. A laminate in which a layer made of a transparent resin having a glass transition temperature lower than the glass transition temperature of a resin having a negative intrinsic birefringence value is laminated on at least one surface of the layer made of a resin having a negative intrinsic birefringence value. A roll roll of the optical laminate (A) formed by uniaxial stretching and a roll roll of the uniaxial stretch film (B) made of a transparent resin are respectively drawn out, and the optical laminate (A) and the uniaxial stretch film are drawn. (B) A roll-shaped optical laminate (C) satisfying the following [1] and [2] by laminating by a roll-to-roll method so that the crossing angle in each stretching direction is 90 ° ± 10 °. The manufacturing method of the optical laminated body (C) to manufacture.
[1] 0 <(nx−nz) / (nx−ny) <1
[2] The variation of the front retardation Re represented by (nx−ny) × d is within ± 10 nm.
(In the above [1] and [2], d is the thickness (nm) of the optical laminate (C), and nz is the refractive index in the thickness direction of the optical laminate (C) measured with light having a wavelength of 550 nm ( -), Nx is the refractive index (-) in the slow axis direction in the plane of the optical laminate (C) measured with light having a wavelength of 550 nm, and ny is the surface of the optical laminate (C) measured with light having a wavelength of 550 nm. The refractive index (−) in the direction perpendicular to the plane of the slow axis direction is shown.) The glass transition temperature of a resin having a negative intrinsic birefringence value is expressed as Tg. ₁ The stretching temperature at which the laminate is uniaxially stretched is (Tg ₁ −10) ° C. to (Tg ₁ The method for producing an optical laminate (C) according to claim 13, wherein the temperature is +20) ° C.