JP2009116197A - Anisotropic light scattering film, manufacturing method thereof, optical film and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an anisotropic light scattering film which can substantially transmit incident light from the front direction, on the other hand, can scatter incident light from the oblique direction and has an angular dependence with respect to light scattering. <P>SOLUTION: The anisotropic light scattering film is characterized in that a dispersion component satisfying a refractive index distribution of nx≈ny<nz are dispersed in a matrix component as domains phase-separated from the matrix component. Therein, nx, ny and nz respectively represent the refractive indexes of a film in the X-axis, Y-axis and Z-axis directions when a material forming the dispersion component is filmed by itself, wherein the X-axis direction is the direction (in-plane slow axis direction) in which the refractive index becomes maximum in the plane of the film; the Y-axis direction is the direction (in-plane fast axis direction) which is vertical to the X-axis direction in the plane of the film; and the Z-axis direction is the thickness direction of the film vertical to the X-axis direction and Y-axis direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an anisotropic light scattering film and a method for producing the same. The anisotropic light scattering film can be used alone or as an optical film combined with a polarizing plate, a retardation plate, a brightness enhancement film, a diffusion sheet, a light collecting sheet, or the like. Furthermore, the present invention relates to an image display device such as a liquid crystal display device, an organic EL display device, a CRT, or a PDP using the anisotropic light scattering film or the optical film.

  Light scattering is a phenomenon in which light refraction, reflection, interference, diffraction, and the like are mixed in a complicated manner, and generally occurs when light rays enter an interface having a difference in refractive index. Anisotropic light scattering film is a kind of anisotropic light scattering element having anisotropy in the intensity of light scattering depending on the direction of incidence of light, and is widely used for applications such as expanding the viewing angle in image display devices such as liquid crystal display devices. in use.

  As a conventional anisotropic light scattering element, for example, there is a type in which a concavo-convex shape is formed on the surface and a refractive index difference at the interface with air is used. In addition, there is a type in which a blind laminated structure composed of layers having different refractive indexes is formed by phase separation, and anisotropy of light scattering is expressed by a diffraction phenomenon resulting therefrom (Patent Document 1). However, these have problems such as a large thickness and a complicated method for controlling anisotropy of light scattering.

  An anisotropic light scattering element is also known in which particles having a refractive index different from that of the medium are dispersed in the medium (Patent Document 2). For example, Patent Document 2 discloses an anisotropic light scattering element in which translucent fine particles having an isotropic refractive index are dispersed in a translucent medium having birefringence. Liquid crystal materials and non-liquid crystalline resins are mentioned. However, in the manufacturing method described in Patent Document 2, in order to give birefringence (refractive index anisotropy) to the medium, alignment of liquid crystal material molecules by an alignment film, an electric field, a magnetic field, etc., or non-liquid crystalline resin Stretching is necessary, and there is a problem in manufacturing simplicity.

  Further, when forming a translucent medium resin film by forming a solution in which isotropic refractive translucent fine particles are dispersed in a birefringent translucent medium resin into a film form and further drying it. There has been proposed a method for producing an anisotropic light scattering film by imparting the birefringence to the translucent medium resin due to the stress generated in (Patent Document 3). However, the anisotropic light scattering film obtained by Patent Document 3 has poor angle dependency of light scattering, and strongly scatters incident light regardless of the incident angle. Therefore, the anisotropic light scattering film obtained by Patent Document 3 has strong light scattering even for incident light from the front direction, and when applied to an image display device such as a liquid crystal display device, it also scatters linearly polarized light from the front direction. The light transmission efficiency deteriorated, and the function as an anisotropic light scattering film was not sufficient.

JP-A 64-077001 Japanese Patent Laid-Open No. 11-029772 JP 2004-361656 A

  An object of the present invention is to provide an anisotropic light-scattering film having an angle dependency with respect to light scattering, which substantially transmits incident light from the front direction and scatters incident light from an oblique direction. And Moreover, an object of this invention is to provide the method which can manufacture the said anisotropic light-scattering film simply.

  Another object of the present invention is to provide an optical film using the anisotropic light scattering film, and further to provide an image display device using the anisotropic light scattering film or the optical film.

  As a result of intensive studies to solve the above problems, the present inventors have found that the object can be achieved by the anisotropic light scattering film shown below, and have completed the present invention.

  That is, the present invention relates to an anisotropic light scattering film characterized in that a dispersion component satisfying a refractive index distribution of nx≈ny <nz is dispersed in a matrix component as a domain separated from the matrix component. .

  However, nx, ny, and nz represent the refractive indexes in the X-axis, Y-axis, and Z-axis directions of the film when the dispersion component forming material is formed into a film alone, and the X-axis direction refers to the film The direction in which the refractive index is maximum in the plane (in-plane slow axis direction), and the Y-axis direction is the direction perpendicular to the X-axis direction (in-plane fast axis direction) in the plane of the film The Z-axis direction is the thickness direction of the film perpendicular to the X-axis direction and the Y-axis direction.

In the anisotropic light scattering film, it is preferable that the refractive index of the dispersion component satisfies the conditions of the following mathematical formulas (1) and (2).
| Nx−ny | ≦ 0.02 (1)
nz− (nx + ny) /2≧0.02 (2)

  In the anisotropic light scattering film, it is preferable that the matrix component satisfies a refractive index distribution of npx> npy≈npz, npx ≧ npy> npz, or npx≈npy≈nz.

  However, npx, npy, and npz indicate the refractive indexes in the X-axis, Y-axis, and Z-axis directions of the film when the matrix component forming material is formed into a single film. The direction in which the refractive index is maximum in the plane (in-plane slow axis direction), and the Y-axis direction is the direction perpendicular to the X-axis direction (in-plane fast axis direction) in the plane of the film The Z-axis direction is the thickness direction of the film perpendicular to the X-axis direction and the Y-axis direction.

In the anisotropic light scattering film, the refractive index of the matrix component and the refractive index of the dispersion component preferably satisfy the following mathematical formulas (3), (4), and (5).
| Nx−npx | ≦ 0.02 (3)
| Ny-npy | ≦ 0.02 (4)
nz−npz ≧ 0.02 (5)

  In the anisotropic light scattering film, a domain formed by phase separation of the dispersion component in the matrix component may have a major axis in the thickness direction of the anisotropic light scattering film and a minor axis in the in-plane direction of the film. preferable.

  The major axis size of the domain is preferably 0.02 to 4 μm, and the minor axis size is preferably 0.01 to 2 μm. Moreover, it is preferable that the average aspect ratio of a major axis size and a minor axis size is 1.5 or more.

  In the anisotropic light scattering film, the content of the dispersion component is preferably 1 to 50% by weight with respect to the total of the matrix component and the dispersion component.

The present invention also provides a method for producing the anisotropic light scattering film,
Preparing a solution containing the matrix component forming material and the dispersion component forming material (1);
Applying the solution onto a substrate (2),
It has the process (3) which forms a film by solidifying the solution apply | coated on the said base material, It is related with the manufacturing method of the anisotropic light-scattering film characterized by the above-mentioned.

  The present invention also relates to an optical film comprising at least one anisotropic light scattering film.

  The present invention also relates to an image display device comprising the anisotropic light scattering film or the optical film.

  In the anisotropic light scattering film of the present invention, as shown in FIG. 1, the dispersion component (A) satisfying the refractive index distribution of nx≈ny <nz is separated from the matrix component in the matrix component (B). The structure is distributed as a domain. In the anisotropic light-scattering film of the present invention, a conceptual diagram of a refractive index ellipsoid of a dispersion component satisfying a refractive index distribution of nx≈ny <nz is shown in FIG. While the refractive index is substantially the same in the direction, that is, the direction in the film plane, the refractive index in the Z-axis direction, that is, the thickness direction of the film is larger than the refractive index in the direction in the film plane. . Since the refractive index ellipsoid is present as a domain in the film plane as a dispersion component, incident light in the front direction (normal direction) with respect to the film is transmitted almost as it is, while on the other hand, Incident light can be scattered by having a high refractive index in the Z-axis direction, and an anisotropic light scattering film having angle dependency of light scattering can be obtained.

  Further, when a matrix component of the anisotropic light scattering film satisfying a refractive index distribution of npx> npy≈npz, npx ≧ npy> npz, or npx≈npy≈nz, In the Y-axis direction, that is, the in-plane direction, the refractive index of the dispersion component is substantially matched, while in the Z-axis direction, that is, the thickness direction of the film, the matrix component and the dispersion component are refracted. The difference in rate can be set to be large, and the incident light in the front direction can be scattered more strongly while the incident light in the front direction is transmitted almost as it is.

  FIG. 2B is a conceptual diagram of a refractive index ellipsoid of a matrix component that satisfies the refractive index distribution of npx≈npy≈nz. FIG. 2C is a conceptual diagram that superimposes FIG. 2A and FIG. 2B on the assumption that the matrix component and the dispersion component have the same refractive index in the film plane direction. As can be seen in FIG. 2C, the refractive index ellipsoid of the dispersion component in FIG. 2A and the refractive index ellipsoid of the matrix component in FIG. On the other hand, it is understood that incident light in an oblique direction is scattered and emitted due to a difference in refractive index in the Z-axis direction.

  Further, in the anisotropic light scattering film, in the matrix component, the dispersed component has a domain having a phase-separated structure in a rod shape having a major axis in the thickness direction of the obtained film and a minor axis in the in-plane direction of the film. Can be formed. Such a unique structure of the domain can also help to effectively perform anisotropic light scattering of incident light from an oblique direction.

  Such an anisotropic light scattering film of the present invention has an angle dependency of light scattering that substantially transmits incident light from the front direction and scatters incident light from an oblique direction. By stacking on the outermost surface of a liquid crystal panel, especially a twisted nematic mode liquid crystal panel, light that leaks from below (light from the liquid crystal panel) is scattered without being distributed in the front direction during black display. In addition, the viewing angle can be expanded without reducing the front connection trust.

  In the anisotropic light scattering film of the present invention, the dispersion component satisfies a refractive index distribution of nx≈ny <nz. For example, a predetermined birefringent liquid crystal polymer is used as a material for forming the dispersion component. By using the film, the liquid crystal polymer can be aligned so as to satisfy the refractive index distribution of nx≈ny <nz by the stress at the time of film formation, and alignment processing by alignment film, electric field, magnetic field, stretching, etc. Even if it does not use, it can manufacture which can manufacture an anisotropic light-scattering film simply.

  In the anisotropic light scattering film of the present invention, as shown in FIG. 1, the matrix component (B) has a dispersion component (A) satisfying a refractive index distribution of nx≈ny <nz. It has a structure that is dispersed as phase separated domains. As the dispersion component (A) and the matrix component (B), those having translucency are preferably used.

  The dispersion component (A) satisfies the refractive index distribution of nx≈ny <nz when the dispersion component forming material is formed into a single film. The dispersion component is such that the optical axis is in the Z-axis direction, the main refractive indexes nx and ny are substantially the same, and nz satisfies a relationship larger than nx and ny. The component (B) is considered to satisfy the same refractive index distribution as described above.

  In addition, nx, ny, and nz are values measured at a temperature of 20 ° C. and a measurement wavelength λ = 589.3 nm using an Abbe refractometer provided with an analyzer in the eyepiece lens portion. The same applies to npx, npy and npz described later.

Moreover, it is preferable that the refractive index of the said dispersion component satisfies the conditions of following Numerical formula (1) and Numerical formula (2).
| Nx−ny | ≦ 0.02 (1)
nz− (nx + ny) /2≧0.02 (2)

  | Nx−ny | is the absolute field of the difference between nx and ny. Therefore, nx≈ny indicates that the difference in refractive index between nx and ny is preferably 0.02 or less. The symbol “≈” indicates that in the present invention, the allowable range of the refractive index difference is preferably the same range as described above.

  The smaller the value of | nx−ny |, the smaller the refractive index difference in the front direction, and the smaller the value, the better the transparency in the front direction. The value of | nx−ny | is preferably 0.01 or less, more preferably 0.005 or less, and ideally 0. Moreover, the larger the value of nz− (nx + ny) / 2, the larger the difference in refractive index in the thickness direction, and the stronger the light scattering in the oblique direction. The value of nz− (nx + ny) / 2 is preferably 0.03 or more, more preferably 0.04 or more, and particularly preferably 0.05 or more. The upper limit value is not particularly limited, but is 0.1 or less, for example. It is.

  As a material for forming the dispersion component, for example, a liquid crystal material exhibiting homeotropic alignment can be used. As the homeotropic alignment liquid crystal material, for example, it can be homeotropically aligned by a vertical alignment agent as described in Chemical Review 44 (Surface Modification, The Chemical Society of Japan, pages 156 to 163). And general nematic liquid crystal compounds.

  Examples of the homeotropic alignment liquid crystal material include a homeotropic alignment side chain type liquid crystal polymer. As the homeotropic alignment side chain type liquid crystal polymer, for example, a side chain type liquid crystal containing a monomer unit (a) containing a liquid crystalline fragment side chain and a monomer unit (b) containing a non-liquid crystalline fragment side chain is used. Polymer.

  The side-chain liquid crystal polymer can be converted into a liquid crystal state by, for example, heat treatment to develop a nematic liquid crystal phase without using a vertical alignment film, thereby realizing homeotropic alignment of the liquid crystal polymer.

  The monomer unit (a) has a side chain having nematic liquid crystallinity, for example, the general formula (a):

(Wherein R ¹ represents a hydrogen atom or a methyl group, a represents a positive integer of 1 to 6, X ¹ represents a —CO ₂ — group or —OCO— group, R ² represents a cyano group, and has 1 to 6 carbon atoms. An alkoxy group, a fluoro group or an alkyl group having 1 to 6 carbon atoms, and b and c each represents an integer of 1 or 2.).

  The monomer unit (b) has a linear side chain. For example, the monomer unit (b) has the general formula (b):

(However, the R ³ is a hydrogen atom or a methyl group, R ⁴ is an alkyl group having 1 to 22 carbon atoms, fluoroalkyl group having 1 to 22 carbon atoms, or the general formula, (b1):

However, d is a positive integer from 1 to 6, R ⁵ represents an alkyl group having 1 to 6 carbon atoms. ) Monomer units.

  Further, the ratio of the monomer unit (a) to the monomer unit (b) is not particularly limited and varies depending on the type of the monomer unit. However, when the ratio of the monomer unit (b) is increased, the side chain type liquid crystal polymer is changed. In order to stop showing liquid crystal monodomain orientation, it is preferable to set it as (b) / {(a) + (b)} = 0.01-0.8 (molar ratio). In particular, 0.1 to 0.5 is more preferable.

  The liquid crystal polymer capable of forming a homeotropic alignment liquid crystal layer includes the monomer unit (a) containing the liquid crystalline fragment side chain and the monomer unit (c) containing a liquid crystalline fragment side chain having an alicyclic ring structure. And a side chain type liquid crystal polymer.

  The side-chain liquid crystal polymer can also realize homeotropic alignment of the liquid crystal polymer without using a vertical alignment film. The monomer unit (c) has a side chain having nematic liquid crystallinity, for example, the general formula (c):

(Wherein R ⁶ represents a hydrogen atom or a methyl group, h represents a positive integer of 1 to 6, X ² represents a —CO ₂ — group or —OCO— group, e and g represent an integer of 1 or 2, f represents an integer of 0 to 2, and R ⁷ represents a cyano group and an alkyl group having 1 to 12 carbon atoms.)

  Further, the ratio of the monomer unit (a) to the monomer unit (c) is not particularly limited and varies depending on the type of the monomer unit. However, when the ratio of the monomer unit (c) is increased, the side chain type liquid crystal polymer is changed. Since the liquid crystal monodomain orientation is not exhibited, it is preferable that (c) / {(a) + (c)} = 0.01 to 0.8 (molar ratio). In particular, 0.1 to 0.6 is more preferable.

  The homeotropic alignment liquid crystal polymer is not limited to those having the above exemplified monomer units, and the above exemplified monomer units can be appropriately combined.

  The side chain type liquid crystal polymer preferably has a weight average molecular weight of 2,000 to 100,000. By adjusting the weight average molecular weight to such a range, performance as a liquid crystal polymer is exhibited. When the weight average molecular weight of the side chain type liquid crystal polymer is too small, the film forming property of the alignment layer tends to be poor. Therefore, the weight average molecular weight is more preferably 2.5000 or more. On the other hand, if the weight average molecular weight is excessive, the orientation as a liquid crystal tends to be poor and it becomes difficult to form a uniform alignment state. Therefore, the weight average molecular weight is more preferably 50,000 or less.

  The illustrated side chain type liquid crystal polymer can be prepared by copolymerizing an acrylic monomer or a methacrylic monomer corresponding to the monomer unit (a), the monomer unit (b), and the monomer unit (c). The monomers corresponding to the monomer unit (a), the monomer unit (b), and the monomer unit (c) can be synthesized by a known method. The copolymer can be prepared, for example, according to a polymerization method such as a conventional acrylic monomer such as a radical polymerization method, a cationic polymerization method, and an anionic polymerization method. When applying the radical polymerization method, various polymerization initiators can be used. Among them, decomposition temperatures such as azobisisobutyronitrile and benzoyl peroxide are not high and are not low. Those are preferably used.

  Although there is no restriction | limiting in particular as a matrix component (B) in an anisotropic light-scattering film, About the said film at the time of forming the forming material of a matrix component independently, the refractive index npz of a Z-axis direction is X-axis direction and Those having a refractive index npx or npy in the Y-axis direction that is equal to or smaller than that can be preferably used. As a material for forming the matrix component (B), for example, a birefringent material satisfying a refractive index distribution of npx> npy≈npz or npx ≧ npy> npz, or a refractive index distribution of npx≈npy≈nz is used. Satisfactory isotropic materials can be used. In the anisotropic light scattering film, the matrix component (B) is considered to satisfy the refractive index distribution similar to that of the material, but the refractive index distribution of the material is not necessarily maintained as it is. For example, the matrix component (B) may have a portion inclined in the thickness direction due to the influence of the dispersion component satisfying the refractive index distribution of nx≈ny <nz.

The refractive index of the matrix component preferably satisfies the following formula (3), formula (4), and formula (5) in relation to the refractive index of the dispersion component.
| Nx−npx | ≦ 0.02 (3)
| Ny-npy | ≦ 0.02 (4)
nz−npz ≧ 0.02 (5)

  The smaller the values of | nx−npx | and | ny−npy |, the difference in refractive index between the matrix component and the dispersion component in the X-axis direction and the Y-axis direction, that is, in the entire film, in the X-axis direction and the Y-axis direction. The refractive indexes are approximately the same, and the transparency in the front direction is improved. The values of | nx−npx | and | ny−npy | are preferably as small as possible, preferably 0.01 or less, more preferably 0.005 or less, and ideally 0. In addition, as the value of nz−npz is larger, the refractive index difference in the thickness direction is larger in the entire film, and light scattering in the oblique direction is stronger. The value of nz−npz is preferably 0.03 or more, more preferably 0.04 or more, and particularly preferably 0.05 or more. The upper limit value is not particularly limited, but is, for example, 0.1 or less.

  As the material for forming the matrix component, a birefringent material satisfying a refractive index distribution of npx> npy≈npz is preferable among the above examples. In particular, a birefringent material satisfying a refractive index distribution of npx> npy≈npz is suitable when a homeotropic liquid crystal material is used as a material for forming a dispersion component.

  The matrix component forming material is not particularly limited as long as it satisfies the refractive index distribution, but is formed by solidifying after applying a solution containing the material onto a substrate. The film obtained preferably satisfies the above refractive index distribution. The solidification means that when the matrix component forming material is a non-reactive material, it is formed into a film by simple solidification by removing a solvent such as drying, and the matrix component forming material is a reactive material. In this case, in addition to the drying and the like, the material is reacted to form a film. Hereinafter, materials that can form the matrix component as described above will be mainly described as the matrix component forming material.

  Examples of the birefringent material that satisfies the refractive index distribution of npx> npy≈npz include nematic liquid crystal monomers. The nematic liquid crystal monomer can be cured after application to form a film satisfying the refractive index distribution.

  Specific examples of the nematic liquid crystal monomer include a monomer represented by the following general formula (1). One type of these liquid crystal monomers may be used, or two or more types may be used in combination.

In the general formula (1), A ¹ and A ² each represent a polymerizable group, and may be the same or different. One of A ¹ and A ² may be hydrogen. X represents a single bond, —O—, —S—, —C═N—, —O—CO—, —CO—O—, —O—CO—O—, —CO—NR—, —NR—, respectively. CO—, —NR—, —O—CO—NR—, —NR—CO—O—, —CH ₂ —O— or —NR—CO—NR, wherein R is H or C1-C4 Represents alkyl, and M represents a mesogenic group. In the general formula (1), Xs may be the same or different, but are preferably the same.

Among the monomers represented by the general formula (1), each A ² is preferably located in the ortho position with respect to A ¹ .

A ¹ and A ² are each independently the following general formula (2):
Z-X- (Sp) _n (2)
And A ¹ and A ² are preferably the same group.

  In the general formula (2), Z represents a crosslinkable group, X is the same as in the general formula (1), and Sp is a linear or branched alkyl group having 1 to 30 C atoms. And n represents 0 or 1. The carbon chain in Sp may be interrupted by, for example, oxygen in the ether functional group, sulfur in the thioether functional group, a non-adjacent imino group, or a C1-C4 alkylimino group.

  In the general formula (2), Z is preferably any one of the atomic groups represented by the following formula. In the following formula, examples of R include groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, and t-butyl.

  In the general formula (2), Sp is preferably any one of the atomic groups represented by the following formula. In the following formula, m is preferably 1 to 3, and p is preferably 1 to 12. .

  In the general formula (1), M is preferably represented by the following general formula (3). In the following general formula (3), X is the same as X in the general formula (1). Q represents, for example, a substituted or unsubstituted alkylene or aromatic hydrocarbon group, and may be, for example, a substituted or unsubstituted linear or branched C1-C12 alkylene.

  When Q is the aromatic hydrocarbon atomic group, for example, an atomic group represented by the following formula or a substituted analog thereof is preferable.

  The substituted analog of the aromatic hydrocarbon group represented by the above formula may have, for example, 1 to 4 substituents per aromatic ring, and may include one aromatic ring or one group. Each may have 1 or 2 substituents. The substituents may be the same or different. Examples of the substituent include C1-C4 alkyl, halogen such as nitro, F, Cl, Br, and I, phenyl, C1-C4 alkoxy, and the like.

  Specific examples of the liquid crystal monomer include monomers represented by the following chemical formulas (4) to (19).

  The temperature range in which the liquid crystal monomer exhibits liquid crystallinity varies depending on the type, but is preferably in the range of 40 to 120 ° C., more preferably in the range of 50 to 100 ° C., and particularly preferably 60. It is the range of -90 degreeC.

  In addition to the nematic liquid crystal monomer exemplified above, examples of the birefringent material that satisfies the refractive index distribution of npx> npy≈npz include polymers obtained from nematic liquid crystal monomers.

  As a birefringent material satisfying the refractive index distribution of npx ≧ npy> npz, polyamide is used because it has excellent translucency (high transparency) and can express large birefringence (high orientation) by drying. , Polymer materials such as polyimide, polyester, polyetherketone, polyamideimide and polyesterimide. These polymer materials may be either homopolymers or heteropolymers. These polymer materials can be used alone or in combination of two or more. Polyetherketone, polyamideimide and polyesterimide refer to a polymer containing an ether bond and a carbonyl group, a polymer containing an amide bond and an imide bond, and a polymer containing an ester bond and an imide bond, respectively. Any one of these polymers may be used alone, or a mixture of two or more having different functional groups such as a mixture of polyaryletherketone and polyamide may be used. . Among such polymers, polyimide is particularly preferable because of higher transparency and higher orientation. Specific examples of these materials include those disclosed in Japanese Patent Application Laid-Open No. 2004-361656.

  Although the molecular weight of the polymer is not particularly limited, for example, the weight average molecular weight (Mw) is preferably in the range of 1,000 to 1,000,000, more preferably in the range of 2,000 to 500,000. is there.

  As the polyimide, for example, a polyimide that has high in-plane orientation and is soluble in an organic solvent is preferable. Specifically, for example, one repeating unit of a condensation polymerization product of 9,9-bis (aminoaryl) fluorene and an aromatic tetracarboxylic dianhydride disclosed in JP 2000-511296 A The polymer containing above can be used. In addition, for example, a homopolymer polyimide of a repeating unit described in JP-A-8-511812 is exemplified.

  Furthermore, examples of the polyimide include a copolymer obtained by appropriately copolymerizing an acid dianhydride other than the skeleton (repeating unit) as described above and a diamine. Examples of the acid dianhydride include aromatic tetracarboxylic dianhydrides. Examples of the aromatic tetracarboxylic dianhydride include pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, naphthalene tetracarboxylic dianhydride, heterocyclic aromatic tetracarboxylic dianhydride, 2, And 2'-substituted biphenyltetracarboxylic dianhydride. Examples of the diamine include aromatic diamines, and specific examples include benzene diamine, diaminobenzophenone, naphthalene diamine, heterocyclic aromatic diamines, and other aromatic diamines.

  Examples of the polyether ketone include polyaryl ether ketones described in JP-A No. 2001-49110. In addition to these, examples of the polyamide or polyester include polyamides and polyesters described in JP-T-10-508048.

  In addition to the birefringent materials exemplified above, birefringent materials satisfying the refractive index distribution of npx ≧ npy> npz include, for example, a cholesteric liquid crystal planar having a selective reflection wavelength other than the visible light region (380 nm to 780 nm). Examples include those in which the orientation state is fixed. Moreover, the thing using the columnar orientation and nematic orientation of a discotic liquid crystal is mentioned. In addition, a discotic liquid crystal material having negative uniaxiality such as a phthalocyanine or triphenylene compound having a molecular spread in a plane and fixing it by developing a nematic phase or a columnar phase can be mentioned. Moreover, the thing which orientated the negative uniaxial crystal in plane is mention | raise | lifted. For example, the negative uniaxial inorganic layered compound is described in detail, for example, in JP-A-6-82777. Moreover, the refractive index distribution can be satisfied by biaxially stretching a plastic material having birefringence.

  Examples of the isotropic material satisfying the refractive index distribution of npx≈npy≈nz include polyolefins such as polycarbonate, polyarylate, polysulfone, and polypropylene, polyesters such as polyethylene terephthalate and polyethylene naphthalate, norbornene polymers, and acrylics. Examples thereof include polymers, styrene polymers, and cellulose polymers. Moreover, these polymers can be used in mixture of 2 or more types. A film satisfying the refractive index distribution can be formed by curing (solidifying) after applying these isotropic polymer materials. Among these isotropic polymers, an acrylic polymer is preferable.

  The anisotropic light scattering film of the present invention is mainly formed of the matrix component forming material and the dispersion component forming material. In the anisotropic light scattering film of the present invention, the content of the dispersion component is not particularly limited, but is 1 to 50% by weight with respect to the total of the matrix component and the dispersion component from the viewpoint of light scattering properties, film strength, and the like. Preferably, it is 1 to 20% by weight, more preferably 5 to 15% by weight.

  Moreover, the anisotropic light-scattering film of this invention has a preferable thing in which the said dispersion component is rod-shaped and phase-separated and forms the domain in the said matrix component. Furthermore, it is preferable that the rod-like domain has a major axis in the thickness direction of the anisotropic light scattering film and a minor axis in the in-plane direction of the film. Such a rod-like domain structure can be obtained by using a homeotropic alignment liquid crystal material, particularly a liquid crystal polymer, as a dispersion component.

  Such a rod-like domain structure has a major axis in the thickness direction of the film, but from the viewpoint of widening the scattering region, the major axis size is preferably 0.02 to 4 μm, and more preferably 0.1 to 3 μm. Furthermore, it is preferably 0.5 to 2 μm. On the other hand, the minor axis size is preferably 0.01 to 2 μm, more preferably 0.05 to 1.5 μm, and further preferably 0.5 to 1 μm. The average aspect ratio of the major axis size in the Z-axis direction and the minor axis size in the X-axis and Y-axis directions of the dispersion component is preferably 1.5 or more from the viewpoint of widening the scattering region. It is preferably 2 or more, more preferably 4 or more. In general, the average aspect ratio is 10 or less.

The anisotropic light scattering film of the present invention is
For example, the step (1) of preparing a solution containing the matrix component forming material and the dispersion component forming material,
Applying the solution onto a substrate (2),
The anisotropic light-scattering film of this invention can be obtained by performing the process (3) which forms a film by solidifying the solution apply | coated on the said base material.

  In the step (1), the matrix component forming material and the dispersion component forming material are dissolved or dispersed in a solution to prepare a solution. The material for forming the matrix component and the material for forming the dispersion component are blended together with the material for forming the matrix component so that the ratio of the material for forming the dispersion component is the above ratio in the obtained anisotropic light scattering film.

  The solvent may dissolve the matrix component forming material and the dispersion component forming material, and the matrix component forming material dissolves, but the dispersion component forming material is dispersed in the solution. You may use what is done. The solvent can be appropriately selected depending on the material. Examples of the solvent include esters such as ethyl acetate, propyl acetate, butyl acetate, isobutyl acetate, butyl propionate and caprolactone, acetone, methyl ethyl ketone, methyl propyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, diethyl ketone, and cyclopentanone. Ketones such as cyclohexanone and methylcyclohexanone, hydrocarbons such as toluene, sulfoxides such as dimethyl sulfoxide, amides such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone, and halogenated hydrocarbons such as methylene chloride and chloroform These solvents may be used, and these solvents may be used alone or in combination of two or more. As the solvent, a combination of an ester solvent and a ketone solvent, in particular, a combination of ethyl acetate and cyclopentanone is preferable in that the dispersed components are more clearly phase separated. The solid content concentration of the solution is usually adjusted to 10 to 50% by weight, preferably 25 to 35% by weight.

  When a photopolymerizable compound is used as the matrix component forming material and / or the dispersion component forming material, a photopolymerization initiator is blended in the solution. Examples of the photopolymerization initiator include Irgacure 907, 184, 651, and 369 manufactured by Ciba Specialty Chemicals. The photopolymerizable compound can be immobilized by irradiation with ultraviolet rays. The addition amount of the photopolymerization initiator is usually preferably about 0.5 to 10 parts by weight, more preferably 1 to 8 parts by weight with respect to 100 parts by weight of the photopolymerizable compound.

  Further, the solution may contain various additives. For example, in the production process, an ultraviolet absorber, an antioxidant, a surfactant, or the like may be appropriately added as needed for any purpose such as imparting leveling properties or improving the durability of the film.

  In addition, when air bubbles enter when stirring the solution, it is considered that the air bubbles cause isotropic scattering after film formation. Therefore, for example, defoaming may be performed immediately before the solution is formed into a film. Although the defoaming method is not particularly limited, for example, a method of standing under a pressurized condition or a vacuum condition, a method of heating at a temperature at which the solvent is less likely to volatilize, and the like can be used.

  Next, in the step (2), the solution is applied onto a substrate. The coating method is not particularly limited, and a known method can be used. For example, a spin coating method, a roll coating method, a flow coating method, a printing method, a dip coating method, a casting film forming method, a bar coating method, Gravure printing method and the like.

  The substrate may have any shape of a glass substrate, a plastic sheet, or a plastic film. The thickness of the substrate is usually about 10 to 1000 μm.

  The plastic film is not particularly limited as long as it does not change with the orientation temperature. For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, polycarbonate polymers, polymethyl Examples thereof include a film made of a transparent polymer such as an acrylic polymer such as methacrylate. Styrene polymers such as polystyrene and acrylonitrile / styrene copolymers, polyethylene, polypropylene, polyolefins having a cyclic or norbornene structure, olefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, nylon and aromatic polyamides, etc. Examples thereof include films made of transparent polymers such as amide polymers. Furthermore, imide polymers, sulfone polymers, polyether sulfone polymers, polyether ether ketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, arylate polymers, polyoxymethylene polymers Examples thereof include a film made of a transparent polymer such as a polymer, an epoxy-based polymer, and a blend of the aforementioned polymers.

  Among the plastic films, a film having a norbornene structure and a plastic film obtained by saponifying a cellulose film have a very small optical anisotropy, and thus can be used with these substrates.

  Next, in step (3), a film is formed by solidifying the solution applied onto the substrate.

  The solution is solidified by drying the solvent when the matrix component forming material and / or the dispersing component forming material does not contain a photopolymerizable compound. The drying temperature and drying time are not particularly limited, and can be set as appropriate according to the concentration of the solution, the type of solvent, and the like. The drying temperature is, for example, 30 to 200 ° C., preferably 50 to 150 ° C., particularly preferably 70 to 130 ° C., and the drying time is, for example, 1 to 50 minutes, preferably 2 to 10 minutes, particularly preferably 3 ~ 5 minutes.

In addition, when the matrix component forming material and / or the dispersion component forming material contains a photopolymerizable compound, the solution is solidified by performing ultraviolet irradiation after the drying. This is carried out by curing the polymerizable compound. The conditions for ultraviolet irradiation are preferably an inert gas atmosphere in order to achieve sufficient surface hardening. Usually, ultraviolet irradiation with an integrated light quantity of 100 to 500 mJ / cm ² is performed. As the ultraviolet irradiation device, a high-pressure mercury ultraviolet lamp, a metal halide UV lamp, or the like can be used.

  In the obtained anisotropic light scattering film, the material for forming the dispersion component is considered to be oriented so as to exhibit a refractive index distribution of nx≈ny <nz, and the matrix component and the dispersion component are phase-separated. And form a domain. The orientation and phase separation of the dispersion component forming material can be obtained by performing the steps (2) to (3). Further, when the matrix component forming material is a birefringent material in the steps (2) to (3), the material is oriented so as to satisfy the refractive index distribution. On the other hand, when the matrix component forming material is an isotropic material, the isotropic property is maintained.

  Although the detailed mechanism by which the orientation and phase separation are caused by the steps (2) to (3) is not clear, the formation material of the matrix component and the dispersion in the process of volatilization of the solvent contained in the solution. Depending on the combination of the component forming materials, it is considered that stress is generated as the volume shrinkage in the thickness direction occurs, and the molecules of the resin are regularly oriented.

  The anisotropic light-scattering film of the present invention can be easily produced by the production method of the present invention, has properties such as excellent performance even when the thickness is small, and is highly practical.

  The thickness of the anisotropic light-scattering film of the present invention is not particularly limited, and may be appropriately determined from the viewpoint of appropriately adjusting the degree of scattering and the thinning of the image display device, but is preferably 0.5 to 300 μm, for example. Is 1 to 100 μm, particularly preferably 10 to 50 μm. The method for controlling the thickness is not particularly limited, but can be controlled by, for example, appropriately adjusting the amount of the solution used when the solution is formed into a film.

  The anisotropic light scattering film of the present invention can be widely used in various image display devices as various optical films.

  The anisotropic light scattering film of the present invention can be used as an anisotropic light scattering element including one or more layers. By having this configuration, it is possible to ensure the scattering intensity, control the scattering anisotropy in the azimuth direction, and the like. The anisotropic light-scattering element may be a simple stack of the anisotropic light-scattering films of the present invention, but from the viewpoint of workability during production and light utilization efficiency during use, an adhesive layer or an adhesive layer is used. Furthermore, it is preferable that the anisotropic light scattering film is laminated via the adhesive layer.

  Moreover, it can use as an anisotropic light-scattering film of this invention, and an optical film containing another optical layer. Examples of the optical layer include a polarizing plate, a retardation plate, an isotropic diffusion layer, a prism sheet (prism array sheet), a microlens sheet (lens array sheet), an antiglare layer (antiglare layer), an antireflection layer, It is preferable to further include at least one of the protective sheets, but is not limited thereto. In addition, the optical film of the present invention may be one in which the optical layer is simply overlapped, but further includes an adhesive layer, and all or part of the components are laminated via the adhesive layer. Is preferred. Hereinafter, the respective components and the like will be described more specifically.

  As the polarizing plate, a polarizer can be used as it is, but one having a transparent protective film on one or both sides of the polarizer is generally used.

  The polarizer is not particularly limited, and various types can be used. Examples of polarizers include dichroic iodine and dichroic dyes on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. Examples thereof include polyene-based oriented films such as those obtained by adsorbing substances and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic material such as iodine is preferable. The thickness of these polarizers is not particularly limited, but is generally about 5 to 80 μm.

  A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching it can be prepared, for example, by immersing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. If necessary, it can be immersed in an aqueous solution such as potassium iodide which may contain boric acid, zinc sulfate, zinc chloride or the like. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with dirt and anti-blocking agents by washing the polyvinyl alcohol film with water, it also has the effect of preventing unevenness such as uneven coloring by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched even in an aqueous solution such as boric acid or potassium iodide or in a water bath.

  As a material constituting the transparent protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is used. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins, cyclic Examples thereof include polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. A transparent protective film is bonded to one side of the polarizer by an adhesive layer. On the other side, as a transparent protective film, (meth) acrylic, urethane-based, acrylurethane-based, epoxy-based, silicone A thermosetting resin such as a system or an ultraviolet curable resin can be used. One or more kinds of arbitrary appropriate additives may be contained in the transparent protective film. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a mold release agent, an anti-coloring agent, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent. The content of the thermoplastic resin in the transparent protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. . When content of the said thermoplastic resin in a transparent protective film is 50 weight% or less, there exists a possibility that the high transparency etc. which a thermoplastic resin originally has cannot fully be expressed.

  Moreover, as a transparent protective film, the polymer film as described in Unexamined-Japanese-Patent No. 2001-343529 (WO01 / 37007), for example, (A) thermoplastic resin which has a substituted and / or unsubstituted imide group in a side chain, ( B) Resin compositions containing thermoplastic resins having substituted and / or unsubstituted phenyl and nitrile groups in the side chains. A specific example is a film of a resin composition containing an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile / styrene copolymer. As the film, a film made of a mixed extruded product of the resin composition or the like can be used. Since these films have a small phase difference and a small photoelastic coefficient, problems such as unevenness due to the distortion of the polarizing plate can be eliminated, and since the moisture permeability is small, the humidification durability is excellent.

  Although the thickness of a transparent protective film can be determined suitably, generally it is about 1-500 micrometers from points, such as workability | operativity, such as intensity | strength and handleability, and thin layer property. 1-300 micrometers is especially preferable, and 5-200 micrometers is more preferable. The transparent protective film is particularly suitable when the thickness is 5 to 150 μm.

  In addition, when providing a transparent protective film on both sides of a polarizer, the protective film which consists of the same polymer material may be used by the front and back, and the protective film which consists of a different polymer material etc. may be used.

  As the transparent protective film of the present invention, it is preferable to use at least one selected from cellulose resin, polycarbonate resin, cyclic polyolefin resin, and (meth) acrylic resin.

  Cellulose resin is an ester of cellulose and fatty acid. Specific examples of the cellulose ester resin include triacetyl cellulose, diacetyl cellulose, tripropionyl cellulose, dipropionyl cellulose and the like. Among these, triacetyl cellulose is particularly preferable. Many products of triacetylcellulose are commercially available, which is advantageous in terms of availability and cost. Examples of commercially available products of triacetyl cellulose include trade names “UV-50”, “UV-80”, “SH-80”, “TD-80U”, “TD-TAC”, and “UZ” manufactured by Fujifilm Corporation. -TAC "and" KC series "manufactured by Konica. In general, these triacetyl celluloses have an in-plane retardation (Re) of almost zero, but a thickness direction retardation (Rth) of about 60 nm.

  In addition, the cellulose resin film with a small thickness direction phase difference is obtained by processing the said cellulose resin, for example. For example, a base film such as polyethylene terephthalate, polypropylene, and stainless steel coated with a solvent such as cyclopentanone and methyl ethyl ketone is bonded to a general cellulose film and dried by heating (for example, at 80 to 150 ° C. for about 3 to 10 minutes). ) And then peeling the base film; a solution obtained by dissolving norbornene resin, (meth) acrylic resin, etc. in a solvent such as cyclopentanone, methyl ethyl ketone, etc. is applied to a general cellulose resin film and dried by heating ( For example, a method of peeling the coated film after 80 to 150 ° C. for about 3 to 10 minutes is mentioned.

  Moreover, as a cellulose resin film with a small thickness direction retardation, the fatty acid cellulose resin film which controlled the fat substitution degree can be used. Generally used triacetyl cellulose has an acetic acid substitution degree of about 2.8. Preferably, the Rth can be reduced by controlling the acetic acid substitution degree to 1.8 to 2.7. Rth can be controlled to be small by adding a plasticizer such as dibutyl phthalate, p-toluenesulfonanilide, acetyltriethyl citrate to the fatty acid-substituted cellulose resin. The addition amount of the plasticizer is preferably 40 parts by weight or less, more preferably 1 to 20 parts by weight, and still more preferably 1 to 15 parts by weight with respect to 100 parts by weight of the fatty acid cellulose resin.

  Specific examples of the cyclic polyolefin resin are preferably norbornene resins. The cyclic olefin-based resin is a general term for resins that are polymerized using a cyclic olefin as a polymerization unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. Resin. Specific examples include ring-opening (co) polymers of cyclic olefins, addition polymers of cyclic olefins, cyclic olefins and α-olefins such as ethylene and propylene (typically random copolymers), And graft polymers obtained by modifying them with an unsaturated carboxylic acid or a derivative thereof, and hydrides thereof. Specific examples of the cyclic olefin include norbornene monomers.

  Various products are commercially available as the cyclic polyolefin resin. As specific examples, trade names “ZEONEX” and “ZEONOR” manufactured by ZEON CORPORATION, product names “ARTON” manufactured by JSR Corporation, “TOPAS” manufactured by TICONA, and product names manufactured by Mitsui Chemicals, Inc. “APEL”.

  The (meth) acrylic resin preferably has a Tg (glass transition temperature) of 115 ° C. or higher, more preferably 120 ° C. or higher, still more preferably 125 ° C. or higher, and particularly preferably 130 ° C. or higher. When Tg is 115 ° C. or higher, the polarizing plate can be excellent in durability. Although the upper limit of Tg of the (meth) acrylic resin is not particularly limited, it is preferably 170 ° C. or less from the viewpoint of moldability. From (meth) acrylic resin, a film having in-plane retardation (Re) and thickness direction retardation (Rth) of almost zero can be obtained.

  As the (meth) acrylic resin, any appropriate (meth) acrylic resin can be adopted as long as the effects of the present invention are not impaired. For example, poly (meth) acrylic acid ester such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meth) acrylic acid ester copolymer, methyl methacrylate-acrylic acid ester- (Meth) acrylic acid copolymer, (meth) methyl acrylate-styrene copolymer (MS resin, etc.), a polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, Methyl methacrylate- (meth) acrylate norbornyl copolymer, etc.). Preferably, poly (meth) acrylate C1-6 alkyl such as poly (meth) acrylate methyl is used. More preferred is a methyl methacrylate resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight).

  Specific examples of (meth) acrylic resins include (meth) acrylic resins having a ring structure in the molecule described in, for example, Acrypet VH and Acrypet VRL20A manufactured by Mitsubishi Rayon Co., Ltd., and JP-A-2004-70296. And a high Tg (meth) acrylic resin system obtained by intramolecular crosslinking or intramolecular cyclization reaction.

  As the (meth) acrylic resin, a (meth) acrylic resin having a lactone ring structure can also be used. It is because it has high mechanical strength by high heat resistance, high transparency, and biaxial stretching.

  Examples of the (meth) acrylic resin having a lactone ring structure include JP 2000-230016, JP 2001-151814, JP 2002-120326, JP 2002-254544, and JP 2005. Examples thereof include (meth) acrylic resins having a lactone ring structure described in Japanese Patent No. 146084.

  The (meth) acrylic resin having a lactone ring structure preferably has a ring pseudo structure represented by the following general formula (Formula 12).

^Wherein, R 1, ^{R 2} and ^{R 3} each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom.

  The content ratio of the lactone ring structure represented by the general formula (Chemical Formula 12) in the structure of the (meth) acrylic resin having a lactone ring structure is preferably 5 to 90% by weight, more preferably 10 to 70% by weight, More preferably, it is 10 to 60% by weight, and particularly preferably 10 to 50% by weight. When the content of the lactone ring structure represented by the general formula (Chemical Formula 12) in the structure of the (meth) acrylic resin having a lactone ring structure is less than 5% by weight, the heat resistance, solvent resistance, and surface hardness are reduced. May be insufficient. When the content ratio of the lactone ring structure represented by the general formula (Chemical Formula 12) in the structure of the (meth) acrylic resin having a lactone ring structure is more than 90% by weight, molding processability may be poor.

  The (meth) acrylic resin having a lactone ring structure has a mass average molecular weight (sometimes referred to as a weight average molecular weight) of preferably 1,000 to 2,000,000, more preferably 5,000 to 1,000,000, still more preferably 10,000 to 500,000, and particularly preferably. Is 50,000 to 500,000. If the mass average molecular weight is out of the above range, it is not preferable from the viewpoint of moldability.

  The (meth) acrylic resin having a lactone ring structure preferably has a Tg of 115 ° C. or higher, more preferably 120 ° C. or higher, still more preferably 125 ° C. or higher, and particularly preferably 130 ° C. or higher. Since Tg is 115 ° C. or higher, for example, when incorporated into a polarizing plate as a transparent protective film, it has excellent durability. Although the upper limit of Tg of the (meth) acrylic resin having the lactone ring structure is not particularly limited, it is preferably 170 ° C. or less from the viewpoint of moldability and the like.

  The (meth) acrylic resin having a lactone ring structure is preferably as the total light transmittance of a molded product obtained by injection molding measured by a method according to ASTM-D-1003 is higher, preferably 85. % Or more, more preferably 88% or more, and still more preferably 90% or more. The total light transmittance is a measure of transparency. If the total light transmittance is less than 85%, the transparency may be lowered.

  As the transparent protective film, one having a front phase difference of less than 40 nm and a thickness direction retardation of less than 80 nm is usually used. The front phase difference Re is represented by Re = (nx−ny) × d. The thickness direction retardation Rth is represented by Rth = (nx−nz) × d. The Nz coefficient is represented by Nz = (nx−nz) / (nx−ny). [However, the refractive indexes in the slow axis direction, the fast axis direction, and the thickness direction of the film are nx, ny, and nz, respectively, and d (nm) is the thickness of the film. The slow axis direction is the direction that maximizes the refractive index in the film plane. ]. In addition, it is preferable that a transparent protective film has as little color as possible. A protective film having a thickness direction retardation value of −90 nm to +75 nm is preferably used. By using a film having a thickness direction retardation value (Rth) of −90 nm to +75 nm, the coloring (optical coloring) of the polarizing plate caused by the transparent protective film can be almost eliminated. The thickness direction retardation value (Rth) is more preferably −80 nm to +60 nm, and particularly preferably −70 nm to +45 nm.

  On the other hand, as the transparent protective film, a phase difference plate having a phase difference with a front phase difference of 40 nm or more and / or a thickness direction retardation of 80 nm or more can be used. The front phase difference is usually controlled in the range of 40 to 200 nm, and the thickness direction phase difference is usually controlled in the range of 80 to 300 nm. When a retardation plate is used as the transparent protective film, the retardation plate functions also as a transparent protective film, so that the thickness can be reduced.

  Examples of the retardation plate include a birefringent film obtained by uniaxially or biaxially stretching a polymer material, a liquid crystal polymer alignment film, and a liquid crystal polymer alignment layer supported by a film. The thickness of the retardation plate is not particularly limited, but is generally about 20 to 150 μm.

  Examples of the polymer material include polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polycarbonate, polyarylate, polysulfone, polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, Polyphenylene sulfide, polyphenylene oxide, polyallylsulfone, polyamide, polyimide, polyolefin, polyvinyl chloride, cellulose resin, cyclic polyolefin resin (norbornene resin), or any of these binary, ternary copolymers, graft copolymers Examples thereof include polymers and blends. These polymer materials become an oriented product (stretched film) by stretching or the like.

  Examples of the liquid crystal polymer include various main chain types and side chain types in which a conjugated linear atomic group (mesogen) imparting liquid crystal alignment is introduced into the main chain or side chain of the polymer. . Specific examples of the main chain type liquid crystal polymer include a nematic alignment polyester liquid crystal polymer, a discotic polymer, and a cholesteric polymer having a structure in which a mesogen group is bonded at a spacer portion that imparts flexibility. Specific examples of the side chain type liquid crystal polymer include polysiloxane, polyacrylate, polymethacrylate, or polymalonate as a main chain skeleton, and a nematic alignment-providing para-substitution through a spacer portion composed of a conjugated atomic group as a side chain. Examples thereof include those having a mesogenic part composed of a cyclic compound unit. These liquid crystal polymers can be prepared by, for example, applying a solution of a liquid crystalline polymer on an alignment surface such as a surface of a thin film such as polyimide or polyvinyl alcohol formed on a glass plate, or an oblique deposition of silicon oxide. This is done by developing and heat treatment.

  The retardation plate may have an appropriate retardation according to the purpose of use, such as those for the purpose of compensating for various wavelength plates or birefringence of liquid crystal layers and compensation of viewing angle, etc. It may be one in which retardation plates are stacked and optical characteristics such as retardation are controlled.

  The retardation plate has a relationship of nx = ny> nz, nx> ny> nz, nx> ny = nz, nx> nz> ny, nz = nx> ny, nz> nx> ny, nz> nx = ny. What is satisfactory is selected and used according to various applications. Note that ny = nz includes not only the case where ny and nz are completely the same, but also the case where ny and nz are substantially the same.

  For example, in a phase difference plate that satisfies nx> ny> nz, a surface plate having a front phase difference of 40 to 100 nm, a thickness direction phase difference of 100 to 320 nm, and an Nz coefficient of 1.8 to 4.5 is used. Is preferred. For example, in a retardation plate (positive A plate) that satisfies nx> ny = nz, it is preferable to use a retardation plate that satisfies a front phase difference of 100 to 200 nm. For example, for a retardation plate (negative A plate) that satisfies nz = nx> ny, it is preferable to use a retardation plate that satisfies a front phase difference of 100 to 200 nm. For example, in a retardation plate satisfying nx> nz> ny, it is preferable to use a retardation plate having a front phase difference of 150 to 300 nm and an Nz coefficient exceeding 0 to 0.7. As described above, for example, a material satisfying nx = ny> nz, nz> nx> ny, or nz> nx = ny can be used.

  The transparent protective film can be appropriately selected according to the applied liquid crystal display device. For example, in the case of VA (including Vertical Alignment, MVA, and PVA), it is desirable that at least one of the polarizing plates (cell side) has a retardation. As specific phase differences, it is desirable that Re = 0 to 240 nm and Rth = 0 to 500 nm. In terms of the three-dimensional refractive index, nx> ny = nz, nx> ny> nz, nx> nz> ny, nx = ny> nz (positive A plate, biaxial, negative C plate) are desirable. In the VA type, it is preferable to use a combination of a positive A plate and a negative C plate, or one biaxial film. When polarizing plates are used above and below the liquid crystal cell, both the upper and lower sides of the liquid crystal cell may have a phase difference, or any one of the upper and lower transparent protective films may have a phase difference.

  For example, in the case of IPS (including In-Plane Switching, FFS), both cases where the transparent protective film on one side of the polarizing plate has a phase difference and does not have a phase difference can be used. For example, when there is no phase difference, it is desirable that the liquid crystal cell does not have a phase difference both above and below (cell side). In the case where the liquid crystal cell has a phase difference, it is desirable that the liquid crystal cell has a phase difference in the upper and lower sides, or the upper and lower sides have a phase difference (for example, nx> nz> ny on the upper side). Biaxial film satisfying the relationship, when there is no retardation on the lower side, positive A plate on the upper side, and positive C plate on the lower side). When it has a phase difference, it is desirable that Re = −500 to 500 nm and Rth = −500 to 500 nm. In terms of the three-dimensional refractive index, nx> ny = nz, nx> nz> ny, nz> nx = ny, nz> nx> ny (positive A plate, biaxial, positive C plate) are desirable.

  In addition, the film which has the said phase difference can be separately bonded to the transparent protective film which does not have a phase difference, and the said function can be provided.

  The transparent protective film may be subjected to surface modification treatment in order to improve adhesiveness with the polarizer before applying the adhesive. Specific examples of the treatment include corona treatment, plasma treatment, flame treatment, ozone treatment, primer treatment, glow treatment, saponification treatment, and treatment with a coupling agent. Further, an antistatic layer can be appropriately formed.

  The surface of the transparent protective film to which the polarizer is not adhered may be subjected to a hard coat layer, an antireflection treatment, an antisticking treatment, or a treatment for diffusion or antiglare.

  The hard coat treatment is applied for the purpose of preventing scratches on the surface of the polarizing plate. For example, a transparent protective film with a cured film excellent in hardness, sliding properties, etc. by an appropriate ultraviolet curable resin such as acrylic or silicone is used. It can be formed by a method of adding to the surface of the film. The antireflection treatment is performed for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like according to the conventional art. In addition, the sticking prevention treatment is performed for the purpose of preventing adhesion with an adjacent layer (for example, a backlight-side diffusion plate).

  The anti-glare treatment is applied for the purpose of preventing the outside light from being reflected on the surface of the polarizing plate and obstructing the visibility of the light transmitted through the polarizing plate. For example, the surface is roughened by a sandblasting method or an embossing method. It can be formed by imparting a fine concavo-convex structure to the surface of the transparent protective film by an appropriate method such as a blending method of transparent fine particles. Examples of the fine particles to be included in the formation of the surface fine concavo-convex structure include conductive materials made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, and the like having an average particle diameter of 0.5 to 20 μm. In some cases, transparent fine particles such as inorganic fine particles, organic fine particles composed of a crosslinked or uncrosslinked polymer, and the like are used. When forming the surface fine uneven structure, the amount of fine particles used is generally about 2 to 70 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of the transparent resin forming the surface fine uneven structure. The antiglare layer may also serve as a diffusion layer (viewing angle expanding function or the like) for diffusing the light transmitted through the polarizing plate to expand the viewing angle.

  The antireflection layer, antisticking layer, diffusion layer, antiglare layer, and the like can be provided on the transparent protective film itself, or can be provided separately from the transparent protective film as an optical layer.

  An adhesive is used for the adhesion treatment between the polarizer and the transparent protective film. Examples of the adhesive include isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latexes, and water-based polyesters. The said adhesive agent is normally used as an adhesive agent which consists of aqueous solution, and contains 0.5 to 60 weight% of solid content normally. In addition to the above, examples of the adhesive between the polarizer and the transparent protective film include an ultraviolet curable adhesive and an electron beam curable adhesive. The electron beam curable polarizing plate adhesive exhibits suitable adhesion to the various transparent protective films. The adhesive used in the present invention can contain a metal compound filler.

  In addition, as an optical film, for example, for formation of a liquid crystal display device such as a reflection plate, an anti-transmission plate, the retardation plate (including wavelength plates such as 1/2 and 1/4), a visual compensation film, and a brightness enhancement film. The optical layer which may be used is mentioned. These can be used alone as an optical film, or can be laminated on the polarizing plate for practical use and used as one layer or two or more layers.

  In particular, a reflective polarizing plate or a semi-transmissive polarizing plate in which a polarizing plate is further laminated with a reflecting plate or a semi-transmissive reflecting plate, an elliptical polarizing plate or a circular polarizing plate in which a retardation plate is further laminated on a polarizing plate, a polarizing plate A wide viewing angle polarizing plate in which a visual compensation film is further laminated on a plate, or a polarizing plate in which a luminance enhancement film is further laminated on a polarizing plate is preferable.

  A reflective polarizing plate is a polarizing plate provided with a reflective layer, and is used to form a liquid crystal display device or the like that reflects incident light from the viewing side (display side). Such a light source can be omitted, and the liquid crystal display device can be easily thinned. The reflective polarizing plate can be formed by an appropriate method such as a method in which a reflective layer made of metal or the like is attached to one surface of the polarizing plate via a transparent protective layer or the like as necessary.

  Specific examples of the reflective polarizing plate include those in which a reflective layer is formed by attaching a foil or a vapor deposition film made of a reflective metal such as aluminum on one side of a transparent protective film matted as necessary. In addition, the transparent protective film may contain fine particles to form a surface fine concavo-convex structure, and a reflective layer having a fine concavo-convex structure thereon. The reflective layer having the fine concavo-convex structure has an advantage that incident light is diffused by irregular reflection to prevent directivity and glaring appearance and to suppress unevenness in brightness and darkness. Moreover, the protective film containing fine particles also has an advantage that incident light and its reflected light are diffused when passing through it and light and dark unevenness can be further suppressed. The reflective layer of the fine concavo-convex structure reflecting the surface fine concavo-convex structure of the transparent protective film is formed by, for example, applying metal to the surface of the transparent protective layer by an appropriate method such as a vacuum deposition method, an ion plating method, a sputtering method, or a plating method. It can be performed by a method of attaching directly to the screen.

  Instead of the method of directly applying the reflecting plate to the transparent protective film of the polarizing plate, the reflecting plate can be used as a reflecting sheet provided with a reflecting layer on an appropriate film according to the transparent film. Since the reflective layer is usually made of metal, the usage form in which the reflective surface is covered with a transparent protective film, a polarizing plate or the like is used to prevent the reflectance from being lowered due to oxidation, and thus to maintain the initial reflectance for a long time. In addition, it is more preferable to avoid a separate attachment of the protective layer.

  The semi-transmissive polarizing plate can be obtained by using a semi-transmissive reflective layer such as a half mirror that reflects and transmits light with the reflective layer. A transflective polarizing plate is usually provided on the back side of a liquid crystal cell, and displays an image by reflecting incident light from the viewing side (display side) when a liquid crystal display device is used in a relatively bright atmosphere. In a relatively dark atmosphere, a liquid crystal display device of a type that displays an image using a built-in power source such as a backlight built in the back side of the transflective polarizing plate can be formed. In other words, the transflective polarizing plate can be used to form liquid crystal display devices that can save energy when using a light source such as a backlight in a bright atmosphere and can be used with a built-in power supply even in a relatively dark atmosphere. It is.

  An elliptically polarizing plate or a circularly polarizing plate in which a retardation plate is further laminated on a polarizing plate will be described. A phase difference plate or the like is used when changing linearly polarized light to elliptically polarized light or circularly polarized light, changing elliptically polarized light or circularly polarized light to linearly polarized light, or changing the polarization direction of linearly polarized light. In particular, a so-called quarter-wave plate (also referred to as a λ / 4 plate) is used as a retardation plate that changes linearly polarized light into circularly polarized light or changes circularly polarized light into linearly polarized light. A half-wave plate (also referred to as a λ / 2 plate) is usually used when changing the polarization direction of linearly polarized light.

  The elliptically polarizing plate is effectively used for black and white display without the above color by compensating (preventing) the coloration (blue or yellow) generated by the birefringence of the liquid crystal layer of the super twist nematic (STN) type liquid crystal display device. It is done. Further, the one in which the three-dimensional refractive index is controlled is preferable because it can compensate (prevent) coloring that occurs when the screen of the liquid crystal display device is viewed from an oblique direction. The circularly polarizing plate is effectively used, for example, when adjusting the color tone of an image of a reflective liquid crystal display device in which an image is displayed in color, and also has an antireflection function.

  The elliptical polarizing plate and the reflective elliptical polarizing plate are obtained by laminating a polarizing plate or a reflective polarizing plate and a retardation plate in an appropriate combination. Such an elliptically polarizing plate or the like can also be formed by sequentially laminating them sequentially in the manufacturing process of the liquid crystal display device so as to be a combination of a (reflective) polarizing plate and a retardation plate. An optical film such as a polarizing plate has an advantage that it can improve the production efficiency of a liquid crystal display device and the like because of excellent quality stability and lamination workability.

  The visual compensation film is a film for widening the viewing angle so that the image can be seen relatively clearly even when the screen of the liquid crystal display device is viewed from a slightly oblique direction rather than perpendicular to the screen. Examples of such a visual compensation phase difference plate include a phase difference plate, an alignment film such as a liquid crystal polymer, and a film in which an alignment layer such as a liquid crystal polymer is supported on a transparent substrate. A normal retardation plate uses a birefringent polymer film that is uniaxially stretched in the plane direction, whereas a retardation plate used as a visual compensation film is biaxially stretched in the plane direction. Birefringent polymer film, biaxially stretched film such as polymer with birefringence with a controlled refractive index in the thickness direction that is uniaxially stretched in the plane direction and stretched in the thickness direction, etc. Used. Examples of the inclined alignment film include a film obtained by bonding a heat shrink film to a polymer film and stretching or / and shrinking the polymer film under the action of the contraction force by heating, and a film obtained by obliquely aligning a liquid crystal polymer. can give. The raw material polymer for the phase difference plate is the same as the polymer described in the previous phase difference plate, preventing coloration due to a change in the viewing angle based on the phase difference by the liquid crystal cell and expanding the viewing angle for good visual recognition. An appropriate one for the purpose can be used.

  In addition, from the viewpoint of achieving a wide viewing angle with good visibility, an optical compensation position in which an alignment layer of a liquid crystal polymer, particularly an optically anisotropic layer composed of a tilted alignment layer of a discotic liquid crystal polymer, is supported by a triacetyl cellulose film. A phase difference plate can be preferably used.

  A polarizing plate obtained by bonding a polarizing plate and a brightness enhancement film is usually provided on the back side of a liquid crystal cell. The brightness enhancement film reflects a linearly polarized light with a predetermined polarization axis or a circularly polarized light in a predetermined direction when natural light is incident due to a backlight such as a liquid crystal display device or reflection from the back side, and transmits other light. In addition, a polarizing plate in which a brightness enhancement film is laminated with a polarizing plate allows light from a light source such as a backlight to enter to obtain transmitted light in a predetermined polarization state, and reflects light without transmitting the light other than the predetermined polarization state. The The light reflected on the surface of the brightness enhancement film is further inverted through a reflective layer or the like provided behind the brightness enhancement film and re-incident on the brightness enhancement film, and part or all of the light is transmitted as light having a predetermined polarization state. Luminance can be improved by increasing the amount of light transmitted through the enhancement film and increasing the amount of light that can be used for liquid crystal display image display or the like by supplying polarized light that is difficult to be absorbed by the polarizer. That is, when light is incident through the polarizer from the back side of the liquid crystal cell without using a brightness enhancement film, light having a polarization direction that does not coincide with the polarization axis of the polarizer is almost polarized. It is absorbed by the polarizer and does not pass through the polarizer. That is, although depending on the characteristics of the polarizer used, approximately 50% of the light is absorbed by the polarizer, and accordingly, the amount of light that can be used for liquid crystal image display or the like is reduced and the image becomes dark. The brightness enhancement film reflects light that has a polarization direction that is absorbed by the polarizer without being incident on the polarizer, and is reflected by the brightness enhancement film, and then inverted through a reflective layer or the like provided behind the brightness enhancement film. The brightness enhancement film transmits only the polarized light in which the polarization direction of the light reflected and inverted between the two is allowed to pass through the polarizer. Since the light is supplied to the polarizer, light such as a backlight can be efficiently used for displaying an image on the liquid crystal display device, and the screen can be brightened.

  A diffusion plate may be provided between the brightness enhancement film and the reflective layer. The polarized light reflected by the brightness enhancement film is directed to the reflective layer or the like, but the installed diffuser plate uniformly diffuses the light passing therethrough and simultaneously cancels the polarized state and becomes a non-polarized state. That is, the light in the natural light state is directed toward the reflection layer or the like, reflected through the reflection layer or the like, and again passes through the diffusion plate and reenters the brightness enhancement film. In this way, by providing a diffuser plate that returns polarized light to the original natural light between the brightness enhancement film and the reflective layer, the brightness of the display screen is maintained, and at the same time, the brightness of the display screen is reduced and uniform. Can provide a bright screen. By providing such a diffuser plate, it is considered that the first incident light has a moderate increase in the number of repetitions of reflection, and in combination with the diffusion function of the diffuser plate, a uniform bright display screen can be provided.

  The brightness enhancement film has a characteristic of transmitting linearly polarized light having a predetermined polarization axis and reflecting other light, such as a multilayer thin film of dielectric material or a multilayer laminate of thin film films having different refractive index anisotropies. Such as an alignment film of a cholesteric liquid crystal polymer or an alignment liquid crystal layer supported on a film substrate, which reflects either left-handed or right-handed circularly polarized light and transmits other light. Appropriate things such as a thing can be used.

  Therefore, in the brightness enhancement film of the type that transmits linearly polarized light having the predetermined polarization axis as described above, the transmitted light is directly incident on the polarizing plate with the polarization axis aligned, thereby efficiently transmitting while suppressing absorption loss due to the polarizing plate. Can be made. On the other hand, in a brightness enhancement film of a type that transmits circularly polarized light such as a cholesteric liquid crystal layer, it can be incident on a polarizer as it is, but from the point of suppressing absorption loss, the circularly polarized light is converted into linearly polarized light through a retardation plate. It is preferably incident on the polarizing plate. Note that circularly polarized light can be converted to linearly polarized light by using a quarter wave plate as the retardation plate.

  A retardation plate that functions as a quarter-wave plate at a wide wavelength in the visible light region or the like exhibits, for example, a retardation plate that functions as a quarter-wave plate for light-colored light having a wavelength of 550 nm and other retardation characteristics. It can be obtained by a method in which a phase difference layer, for example, a phase difference layer that functions as a half-wave plate is superimposed. Therefore, the retardation plate disposed between the polarizing plate and the brightness enhancement film may be composed of one or more retardation layers.

  In addition, a cholesteric liquid crystal layer having a reflection structure that reflects circularly polarized light in a wide wavelength range such as a visible light range can be obtained by combining two or more layers with different reflection wavelengths to form an overlapping structure. Based on this, transmitted circularly polarized light in a wide wavelength range can be obtained.

  Further, the polarizing plate may be formed by laminating a polarizing plate and two or more optical layers as in the above-described polarization separation type polarizing plate. Therefore, a reflective elliptical polarizing plate or a semi-transmissive elliptical polarizing plate in which the above-described reflective polarizing plate or semi-transmissive polarizing plate and a retardation plate are combined may be used.

  An optical film in which the optical layer is laminated on a polarizing plate can be formed by a method of sequentially laminating separately in the manufacturing process of a liquid crystal display device or the like. There is an advantage that the manufacturing process of a liquid crystal display device or the like can be improved because of excellent stability and assembly work. For the lamination, an appropriate adhesive means such as an adhesive layer can be used. When adhering the polarizing plate and the other optical layer, their optical axes can be set at an appropriate arrangement angle in accordance with a target phase difference characteristic.

  The anisotropic light-scattering film of the present invention and the optical film in which at least one layer of the anisotropic light-scattering film is laminated may be provided with an adhesive layer for adhering to other members. The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited. For example, an acrylic polymer, silicone-based polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer is appropriately selected. Can be used. In particular, those having excellent optical transparency such as an acrylic pressure-sensitive adhesive, exhibiting appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and being excellent in weather resistance, heat resistance and the like can be preferably used.

  In addition to the above, in terms of prevention of foaming and peeling phenomena due to moisture absorption, deterioration of optical properties and liquid crystal cell warpage due to differences in thermal expansion, etc., as well as formability of liquid crystal display devices with high quality and excellent durability An adhesive layer having a low moisture absorption rate and excellent heat resistance is preferred.

  The adhesive layer is, for example, natural or synthetic resins, in particular, tackifier resins, fillers or pigments made of glass fibers, glass beads, metal powders, other inorganic powders, colorants, antioxidants, etc. It may contain an additive to be added to the adhesive layer. Moreover, the adhesion layer etc. which contain microparticles | fine-particles and show light diffusibility may be sufficient.

  The attachment of the pressure-sensitive adhesive layer to one or both surfaces of the anisotropic light scattering film or the optical film can be performed by an appropriate method. For example, a pressure sensitive adhesive solution of about 10 to 40% by weight in which a base polymer or a composition thereof is dissolved or dispersed in a solvent composed of a suitable solvent alone or a mixture such as toluene and ethyl acetate is prepared. A method in which it is directly attached on a polarizing plate or an optical film by an appropriate development method such as a casting method or a coating method, or an adhesive layer is formed on a separator according to the above, and it is formed on an anisotropic light scattering film or Examples include a method of transferring onto an optical film.

  The pressure-sensitive adhesive layer can be provided on one side or both sides of an anisotropic light scattering film or an optical film as a superimposed layer of different compositions or types. Moreover, when providing in both surfaces, it can also be set as adhesive layers, such as a different composition, a kind, and thickness, in the front and back of an anisotropic light-scattering film or an optical film. The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to the purpose of use and adhesive force, and is generally 1 to 500 μm, preferably 1 to 200 μm, and particularly preferably 1 to 100 μm.

  On the exposed surface of the adhesive layer, a separator is temporarily attached and covered for the purpose of preventing contamination until it is put to practical use. Thereby, it can prevent contacting an adhesion layer in the usual handling state. As the separator, except for the above thickness conditions, for example, a suitable thin leaf body such as a plastic film, rubber sheet, paper, cloth, non-woven fabric, net, foam sheet, metal foil, laminate thereof, and the like, silicone type or Appropriate conventional ones such as those coated with an appropriate release agent such as long-chain alkyl, fluorine-based, or molybdenum sulfide can be used.

  In the present invention, the above-mentioned anisotropic light scattering film, optical film, etc., and each layer such as an adhesive layer include, for example, salicylic acid ester compounds, benzophenol compounds, benzotriazole compounds, cyanoacrylate compounds, nickel complex compounds. It is also possible to use one having a UV-absorbing ability by a method such as a method of treating with a UV absorber.

  The anisotropic light scattering film or optical film of the present invention can be preferably used for forming various devices such as a liquid crystal display device. The liquid crystal display device can be formed according to the conventional method. That is, the liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, an anisotropic light scattering film or an optical film, and an illumination system as required, and incorporating a drive circuit. Is not particularly limited except that the anisotropic light-scattering film or optical film of the present invention is used, and can be based on the conventional method. As the liquid crystal cell, an arbitrary type such as an arbitrary type such as a TN type, STN type, π type, VA type, or IPS type can be used.

  Appropriate liquid crystal display devices such as a liquid crystal display device in which a polarizing plate (with an anisotropic light scattering film) or an optical film is disposed on one side or both sides of a liquid crystal cell, or a backlight or reflector used in an illumination system are formed. be able to. In that case, the polarizing plate (with an anisotropic light scattering film) or the optical film according to the present invention can be installed on one side or both sides of the liquid crystal cell. When providing a polarizing plate (with an anisotropic light-scattering film) or an optical film on both sides, they may be the same or different. Further, when forming a liquid crystal display device, for example, a single layer or a suitable part such as a diffusing plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusing plate, a backlight, etc. Two or more layers can be arranged.

  Next, an organic electroluminescence device (organic EL display device) will be described. Generally, in an organic EL display device, a transparent electrode, an organic light emitting layer, and a metal electrode are sequentially laminated on a transparent substrate to form a light emitter (organic electroluminescent light emitter). Here, the organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative and the like and a light emitting layer made of a fluorescent organic solid such as anthracene, Alternatively, a structure having various combinations such as a laminate of such a light emitting layer and an electron injection layer composed of a perylene derivative or the like, or a laminate of these hole injection layer, light emitting layer, and electron injection layer is known. It has been.

  In organic EL display devices, holes and electrons are injected into the organic light-emitting layer by applying a voltage to the transparent electrode and the metal electrode, and the energy generated by recombination of these holes and electrons excites the phosphor material. Then, light is emitted on the principle that the excited fluorescent material emits light when returning to the ground state. The mechanism of recombination in the middle is the same as that of a general diode, and as can be predicted from this, the current and the emission intensity show strong nonlinearity with rectification with respect to the applied voltage.

  In an organic EL display device, in order to extract light emitted from the organic light emitting layer, at least one of the electrodes must be transparent, and a transparent electrode usually formed of a transparent conductor such as indium tin oxide (ITO) is used as an anode. It is used as. On the other hand, in order to facilitate electron injection and increase luminous efficiency, it is important to use a material having a small work function for the cathode, and usually metal electrodes such as Mg—Ag and Al—Li are used.

  In the organic EL display device having such a configuration, the organic light emitting layer is formed of a very thin film having a thickness of about 10 nm. For this reason, the organic light emitting layer transmits light almost completely like the transparent electrode. As a result, light that is incident from the surface of the transparent substrate at the time of non-light emission, passes through the transparent electrode and the organic light emitting layer, and is reflected by the metal electrode is again emitted to the surface side of the transparent substrate. The display surface of the organic EL display device looks like a mirror surface.

  In an organic EL display device comprising an organic electroluminescent light emitting device comprising a transparent electrode on the surface side of an organic light emitting layer that emits light upon application of a voltage and a metal electrode on the back side of the organic light emitting layer, the surface of the transparent electrode While providing a polarizing plate on the side, a retardation plate can be provided between the transparent electrode and the polarizing plate.

  Since the retardation plate and the polarizing plate have a function of polarizing light incident from the outside and reflected by the metal electrode, there is an effect that the mirror surface of the metal electrode is not visually recognized by the polarization action. In particular, the mirror surface of the metal electrode can be completely shielded by configuring the retardation plate with a quarter-wave plate and adjusting the angle formed by the polarization direction of the polarizing plate and the retardation plate to π / 4. .

  That is, only the linearly polarized light component of the external light incident on the organic EL display device is transmitted by the polarizing plate. This linearly polarized light becomes generally elliptically polarized light by the phase difference plate, but becomes circularly polarized light particularly when the phase difference plate is a quarter wavelength plate and the angle formed by the polarization direction of the polarizing plate and the phase difference plate is π / 4. .

  This circularly polarized light is transmitted through the transparent substrate, the transparent electrode, and the organic thin film, is reflected by the metal electrode, is again transmitted through the organic thin film, the transparent electrode, and the transparent substrate, and becomes linearly polarized light again on the retardation plate. And since this linearly polarized light is orthogonal to the polarization direction of a polarizing plate, it cannot permeate | transmit a polarizing plate. As a result, the mirror surface of the metal electrode can be completely shielded.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

Example 1
An anisotropic light scattering film was produced as follows. The following chemical formula 13 (Chemical formula 13):

10 parts by weight of a side chain type liquid crystalline acrylic polymer represented by the formula (wherein the number represents the mol% of the monomer unit and is conveniently represented by a block polymer body, weight average molecular weight 5000), In 90, 90 parts by weight of a liquid crystalline diacrylic monomer represented by the chemical formula (10) in FIG. 10 and 7.5 parts by weight of a photopolymerization disclosure agent (product name: Irgacure 907) are mixed with cyclopentanone and ethyl acetate. A coating solution was prepared by dissolving in a solvent (8: 2 by weight) and adjusting the concentration to 30% by weight. This coating solution was coated on a substrate (manufactured by Nippon Zeon Co., Ltd., product name: ZEONOR ZF-100) using a coater with a wire bar, dried at 80 ° C. for 3 minutes, and further integrated light quantity 300 mJ / By irradiating with ultraviolet rays at cm ² , an anisotropic light scattering film having a film thickness of 3 μm was obtained.

  The material for forming the dispersion component is the above-mentioned side chain type liquid crystalline acrylic polymer, and the material for forming the matrix component is the above liquid crystalline diacrylic monomer. It was separately confirmed that these films satisfy the refractive index distribution of nx≈ny <nz and the refractive index distribution of npx> npy≈npz, respectively, when formed into a film alone. These confirmations were performed at 23 ° C. and a wavelength of 590 nm using an automatic birefringence measuring device (manufactured by Oji Scientific Instruments, automatic birefringence meter KOBRA-WPR).

Example 2
In Example 1, an anisotropic light-scattering film having a thickness of 3 μm was prepared by the same operation as in Example 1 except that only cyclopentanone was used as the solvent instead of the mixed solvent when preparing the coating liquid. Obtained.

  The following evaluation was performed about the anisotropic light-scattering film obtained in the Example. The results are shown in Table 1.

(Evaluation of cross-sectional structure)
The anisotropic light scattering film was dyed for 2 minutes with a saturated vapor of a 2 wt% aqueous solution of ruthenium tetroxide and then embedded in an epoxy resin. After that, the film was processed into an approximately 80 nm slice by an ultrathin slice method, and the phase separation structure (domain shape of dispersed component) of the film cross section was applied to a transmission electron microscope (H-7650, acceleration voltage 100 kV). And observed. Regarding the phase separation structure, the major axis size in the thickness direction, the minor axis size in the in-plane direction, and the average aspect ratio are also shown. In addition, average aspect ratio computed the aspect ratio (major axis size / minor axis size) from the phase-separation structure about ten samples from the transmission electron microscope, and calculated those average values.

(Evaluation of scattering)
Linearly polarized light was incident on the anisotropic light scattering film at incident angles of 0 ° and 45 °, respectively, and the transmitted light was visually observed to evaluate the degree of scattering.

  As shown in Table 1, the anisotropic light-scattering film obtained in the example transmitted the linearly polarized light having an incident angle of 0 ° with little scattering, and scattered the linearly polarized light having an incident angle of 45 °. From this, it can be seen that the anisotropic light scattering films of the examples have good scattering angle dependency and light transmission efficiency in the front direction, and have good properties as anisotropic light scattering films.

  Next, the anisotropic light scattering film of Example 1 of Example 1 was transferred from the base material onto the outermost surface of the viewing side polarizing plate of the twisted nematic mode liquid crystal panel using an acrylic adhesive. When the performance of the liquid crystal panel was evaluated by visual observation before and after transfer and compared, the anisotropic light scattering film of Example 1 caused a decrease in image quality in the front direction and a large decrease in front luminance. In other words, it was confirmed that the effect of suppressing the problem of gradation inversion at a wide viewing angle can be obtained.

It is a schematic diagram which shows the cross section of an example of the anisotropic light-scattering film of this invention. It is a figure explaining the scattering by the difference of the refractive index ellipsoid of a matrix component and a dispersion component.

Explanation of symbols

A Matrix component B Dispersion component

Claims (11)

An anisotropic light-scattering film, wherein a dispersed component satisfying a refractive index distribution of nx≈ny <nz is dispersed in a matrix component as a domain separated from the matrix component.
However, nx, ny, and nz represent the refractive indexes in the X-axis, Y-axis, and Z-axis directions of the film when the dispersion component forming material is formed into a film alone, and the X-axis direction refers to the film The direction in which the refractive index is maximum in the plane (in-plane slow axis direction), and the Y-axis direction is the direction perpendicular to the X-axis direction (in-plane fast axis direction) in the plane of the film The Z-axis direction is the thickness direction of the film perpendicular to the X-axis direction and the Y-axis direction. The anisotropic light-scattering film according to claim 1, wherein the refractive index of the dispersion component satisfies the conditions of the following formulas (1) and (2).
| Nx−ny | ≦ 0.02 (1)
nz− (nx + ny) /2≧0.02 (2)
It is. The anisotropic light-scattering film according to claim 1, wherein the matrix component satisfies a refractive index distribution of npx> npy≈npz, npx ≧ npy> npz, or npx≈npy≈nz.
However, npx, npy, and npz indicate the refractive indexes in the X-axis, Y-axis, and Z-axis directions of the film when the matrix component forming material is formed into a single film. The direction in which the refractive index is maximum in the plane (in-plane slow axis direction), and the Y-axis direction is the direction perpendicular to the X-axis direction (in-plane fast axis direction) in the plane of the film The Z-axis direction is the thickness direction of the film perpendicular to the X-axis direction and the Y-axis direction. The refractive index of the matrix component and the refractive index of the dispersion component satisfy the following formula (3), formula (4), and formula (5), respectively. Anisotropic light scattering film.
| Nx−npx | ≦ 0.02 (3)
| Ny-npy | ≦ 0.02 (4)
nz−npz ≧ 0.02 (5)   The domain formed by phase separation of the dispersed component in the matrix component has a major axis in the thickness direction of the anisotropic light scattering film and a minor axis in the in-plane direction of the film. 4. The anisotropic light scattering film according to any one of 4 above.   6. The anisotropic light scattering film according to claim 5, wherein the major axis size of the domain is 0.02 to 4 [mu] m and the minor axis size is 0.01 to 2 [mu] m.   The anisotropic light scattering film according to claim 5 or 6, wherein an average aspect ratio of the major axis size and the minor axis size of the domain is 1.5 or more.   The anisotropic light-scattering film according to claim 1, wherein the content of the dispersed component is 1 to 50% by weight based on the total of the matrix component and the dispersed component. A method for producing an anisotropic light scattering film according to claim 1,
Preparing a solution containing the matrix component forming material and the dispersion component forming material (1);
Applying the solution onto a substrate (2),
A method for producing an anisotropic light scattering film, comprising a step (3) of forming a film by solidifying a solution applied on the substrate.   An optical film comprising at least one anisotropic light-scattering film according to claim 1.   An image display device comprising the anisotropic light scattering film according to claim 1 or the optical film according to claim 10.

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