JP2008287254A - Polarizing film, laminated film and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated film which can optically compensate a retardation of a liquid crystal cell at a high degree and can provide the expansion of an angle of visibility etc., by obtaining a polarizing film with which the orthogonal relation of the absorption axes on the front and the rear of the liquid crystal cells can be formed by arbitrarily setting a transverse size, the upsizing of the screen of a liquid crystal display, more particularly the screen of the arbitrary transverse size can be achieved, a retardation film and a long film can be laminated on each other and the laminated film consisting of the laminate thereof can be efficiently manufactured. <P>SOLUTION: The polarizing film consists of a long polymer film, contains a dichromatic material therein and has the absorption axis in a transverse direction. The laminated film consists of such polarizing film and the long polymer film and is formed by laminating these films and the retardation film having a slow axis in a longitudinal direction by making the longitudinal directions of the long films corespondent to each other. The liquid crystal display device is formed by arranging the polarizing film or the laminated film on the outer side of the liquid crystal cells. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polarizing film suitable for increasing the size of a liquid crystal display, a superimposing film suitable for optical compensation of a phase difference by a liquid crystal cell, and a liquid crystal display device in which they are arranged.

  In a liquid crystal display such as an IPS mode or a VA mode, polarizers are arranged so that absorption axes (vibration directions of light that cause absorption) are orthogonal to each other on the front and back of the liquid crystal cell. A long polarizing film formed by dyeing a polyvinyl alcohol film or the like with a dichroic material is formed by uniaxially stretching the long film in its length direction, and in this case, the absorption axis of the polarizing film is the length direction. Appears in

  In the above-mentioned long polarizing film, the long film is cut into a film piece of a predetermined size, which is a length direction (MD direction) based on the long film and a width direction (in a direction orthogonal to the direction) By using in combination with the short side direction (TD direction), the orthogonal relationship between the absorption axes on the front and back sides of the liquid crystal cell is achieved.

  Therefore, in the above, since the polarizing film piece is used in a relationship rotated by 90 degrees based on the absorption axis, when obtaining the polarizing film piece of the same size applied to the front and back of the liquid crystal cell, the width of the long film (width direction) Is the critical size. In that case, the conventional polarizing film has a problem in that the width is not sufficient due to shrinkage in the width direction due to uniaxial stretching, and the liquid crystal display has a large screen, in particular, the lateral length is suppressed. Expansion of the width dimension of a long film has a limit from the point of the processing precision to polarizing films, such as orientation precision and a polarization degree, for example.

  On the other hand, for optical compensation of retardation using a liquid crystal cell, in particular for viewing angle compensation, the retardation film is arranged so that its slow axis (maximum refractive index direction in the plane) is perpendicular to the absorption axis of the polarizing film. It is required to do. In that case, the ability to laminate the polarizing film and the retardation film between the long films wound in a roll form is advantageous from the viewpoint of the production efficiency of the superimposed film made of the laminate.

The above is achieved by stretching a long film in the width direction and forming a retardation film having a slow axis in the width direction. However, in that case, the direction of the slow axis varies due to the bowing phenomenon in which the central portion of the film advances compared to the case in which a long film is stretched in the length direction and the retardation film has a slow axis in the length direction. There was an easy difficulty.
Japanese Patent Laid-Open No. 3-24502 JP-A-3-33719

  The present invention can arbitrarily set the horizontal size to form an orthogonal relationship between the absorption axes on the front and back of the liquid crystal cell, can achieve a large screen of the liquid crystal display, in particular, a screen of an arbitrary horizontal size, and a retardation film. Development of a superposition film that can be laminated between long films, obtain a polarizing film that can efficiently produce a superposition film made of the laminate, and can optically compensate for the phase difference of the liquid crystal cell and increase the viewing angle, etc. With the goal.

  The present invention comprises a long polymer film, the film containing a dichroic substance and having an absorption axis in the width direction, the polarizing film, and a long polymer film. A superposition film formed by laminating a retardation film having a slow axis in the length direction and corresponding to the length directions of the long films, and the polarizing film or the superposition film is disposed outside the liquid crystal cell. A liquid crystal display device is provided.

  According to the present invention, a long polarizing film having an absorption axis in the width direction can be obtained, and the length in the length direction, that is, the lateral size can be arbitrarily set, and the absorption axis in the length direction. In combination with a long polarizing film having the above, an orthogonal relationship between absorption axes on the front and back of the liquid crystal cell can be formed by dealing with a screen of an arbitrary horizontal size, and a large screen of the liquid crystal display can be achieved. Further, widening can be achieved by stretching in the width direction. Incidentally, a long polarizing film having a width of 1200 mm can be used in the above combination to form a liquid crystal screen of up to 95 inches with an aspect ratio of 16: 9.

  Furthermore, by being a long polarizing film having an absorption axis in the width direction, a combination of a long retardation film having a slow axis in the length direction, the absorption axis of the polarizing film and the retardation phase of the retardation film An orthogonal relationship with the axis can be formed by laminating the length directions of the long films, and the laminated film made of the laminated body is efficiently processed by laminating the long films wound in a roll state. Can be manufactured well.

  In addition, since a film that has been stretched in the length direction can be used as a phase difference film, variations in the direction of the slow axis due to the bowing phenomenon are unlikely to occur, resulting in excellent axial accuracy, and optical compensation for the phase difference of the liquid crystal cell with high accuracy. Thus, a uniform liquid crystal display can be achieved, and a superimposed film capable of increasing the viewing angle can be obtained.

  The polarizing film according to the present invention comprises a long polymer film, the film contains a dichroic substance, and has an absorption axis in the width direction. The polymer that forms the film may be an appropriate polymer such as a homopolymer, a copolymer, or a mixture of two or more polymers, and the type thereof is not particularly limited. In general, one or more hydrophilic polymers such as polyvinyl alcohol, partially formalized polyvinyl alcohol, ethylene / vinyl alcohol copolymer, and partially saponified ethylene / vinyl acetate copolymer, and polyester are used.

  The long polymer film is preferably a long product having a length of 5 times or more of the width, especially 100,000 to 100,000 times, particularly 30 to 5,000 times, and may be wound in a roll form. . The film width can be appropriately determined according to the application of the polarizing film to be formed, and is generally 5 mm to 5 m, especially 30 cm to 3 m, especially 50 cm to 2 m.

  The polarizing film can be formed by subjecting a long polymer film to a dichroic dyeing process and a widthwise stretching process, and thus exhibits a property of transmitting linearly polarized light when natural light is incident thereon. An absorption-type polarizing film can be obtained. Each of the above processes can be performed simultaneously on the entire long film, or partial processes can be repeated sequentially to affect the entire long film.

  The stretching process in the width direction is intended to have an absorption axis in the width direction of the long film, and in the present invention, except that the absorption axis is in the width direction by stretching in the width direction. A polarizing film can be formed by applying a similar treatment. Therefore, for example, one or two or more suitable substances such as iodine and a dichroic dye can be used as the dichroic substance.

  In addition, as a dichroic substance dyeing method, for example, a method of introducing and immersing a long polymer film in an aqueous solution containing a dichroic material, a method of coating the aqueous solution on a long polymer film, etc. Is given. The dyeing treatment can be performed before, after, or simultaneously with the stretching treatment in the width direction. In particular, it is preferably performed after the stretching treatment from the viewpoint of improving the degree of polarization by preventing the occurrence of uneven dyeing.

  The stretching process in the width direction of the long polymer film can be performed using, for example, a tenter stretching machine. In addition, as a stretching treatment method, the polymer film is heated in the air at a temperature lower than its melting temperature, especially above the glass transition temperature and stretched, for example, in an aqueous solution containing boric acid or the like. Examples thereof include a wet stretching method for stretching.

  In addition to stretching in the width direction (lateral stretching), a long polymer film can be shrunk in the length direction (longitudinal contraction) in order to obtain a highly polarizing film with high uniaxial orientation in the width direction. preferable. The process combining the transverse stretching and the longitudinal contraction can be performed by simultaneous or sequential biaxial processing using a biaxial stretching machine such as a pantograph system or a spindle system.

  The stretching ratio in the width direction can be determined as appropriate, but in general, it is 1.1 to 20 times the initial width dimension, in particular 1.5 to 10 times, especially 2 to 7 in terms of orientation accuracy and widening effect. Doubled. When the above-described longitudinal shrinkage is combined, the shrinkage rate is 70 to 99% of the initial length (100%), especially 75 to 98%, particularly 80 to 97%, from the viewpoint of improving the degree of orientation. It is preferable to do. The thickness of the polarizing film is generally 1 to 200 μm, in particular 3 to 150 μm, particularly 5 to 80 μm, but is not limited thereto. The polarizing film may be subjected to a crosslinking treatment using a crosslinking agent such as boric acid as described above.

  The polarizing film may be provided with a transparent protective layer on one side or both sides as necessary. The transparent protective layer can be provided for various purposes such as reinforcement of the polarizing film, improvement in heat resistance and moisture resistance, improvement in handleability and durability. An appropriate transparent material can be used for forming the transparent protective layer. In particular, polymers having excellent transparency, mechanical strength, thermal stability, moisture shielding properties, and the like are preferably used.

  Incidentally, examples of the polymer include acetate resin such as triacetyl cellulose, polyester resin, polyether sulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, acrylic resin, or acrylic resin. And thermosetting type such as urethane type, acrylic urethane type, epoxy type and silicone type, or ultraviolet curable type resin.

  The transparent protective layer can be formed by an appropriate method such as a polymer coating method or a film-based lamination method via an adhesive layer. The adhesive layer is not particularly limited. From the viewpoint of lamination treatment that is difficult to peel off due to the influence of humidity and heat, for example, an adhesive made of acrylic polymer or vinyl alcohol polymer, boric acid, borax, glutaraldehyde, melamine, A layer made of an adhesive comprising at least a water-soluble crosslinking agent of a vinyl alcohol polymer such as oxalic acid is preferred.

  The thickness of the transparent protective layer is arbitrary but is generally 300 μm or less, in particular 1 to 200 μm, particularly 5 to 100 μm. In addition, when providing a transparent protective layer on both sides of a polarizing film, it can also be set as the transparent protective layer which consists of a polymer etc. which are different in the front and back.

  The polarizing film may be subjected to various treatments for the purpose of hard coating treatment, antireflection treatment, antisticking treatment, diffusion or antiglare, for example. Hard coat treatment is applied for the purpose of preventing scratches on the surface of the polarizing film. For example, hardness, slipperiness, etc. with an appropriate ultraviolet curable resin such as silicone, urethane, acrylic or epoxy. It can be formed by a method of adding a cured film or film having excellent resistance to the surface of the transparent protective layer.

  The antireflection treatment is performed for the purpose of preventing the reflection of external light on the surface of the polarizing film. For example, a light interference film such as a coating layer of a fluorine-based polymer or a multilayer metal deposition film or a reflection according to a conventional method is used. It can be appropriately formed as a prevention film.

  Anti-sticking is for the purpose of preventing adhesion to the adjacent layer, and the anti-glare treatment layer is for the purpose of preventing the external light from being reflected on the surface of the polarizing film and hindering the viewing of the light transmitted through the polarizing film. Yes, for example, by forming a fine uneven structure on the surface by an appropriate method such as a resin coating layer containing transparent fine particles, embossing, sandblasting or etching, etc. be able to.

  Examples of the transparent fine particles include inorganic materials having an average particle diameter of 0.5 to 20 μm, such as silica, calcium oxide, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, and antimony oxide. One type or two or more types of fine particles, or crosslinked or uncrosslinked organic fine particles made of a suitable polymer such as polymethyl methacrylate or polyurethane can be used. The amount of the transparent fine particles used is generally 2 to 70 parts by weight, especially 5 to 50 parts by weight per 100 parts by weight of the transparent resin.

  The anti-glare treatment layer may also serve as a diffusion layer (such as a viewing angle compensation function) for diffusing the light transmitted through the polarizing film to expand the viewing angle. The hard coat layer, antireflection layer, anti-sticking layer, diffusion layer or anti-glare layer is provided as an optical layer composed of a sheet provided with these layers as a separate layer from the transparent protective layer. You can also. Therefore, the polarizing film may be provided with an optical layer for controlling the glare and the scattered light related to the resolution by using diffusion, scattering, refraction and the like, or controlling the viewing angle.

  Moreover, a polarizing film can also be provided practically as a superimposed film formed by laminating a retardation layer on one side or both sides thereof. In that case, by using a retardation film consisting of a long polymer film and having a slow axis in the length direction, the long polarizing film and the long retardation film are made to correspond to each other in the length direction. By laminating the layers, a superimposed film in which the absorption axis of the polarizing film and the slow axis of the retardation film are orthogonal to each other can be formed, and the production efficiency is excellent.

  A retardation film having a slow axis in the length direction, for example, when a long polymer film is transported through a plurality of rolls, the peripheral speed of the transport rolls is made different so that tension is applied in the length direction of the film. It can be formed by a roll type longitudinal stretching method in which longitudinal uniaxial stretching is performed under load. In the longitudinal stretching, a retardation film excellent in uniformity of orientation axes can be obtained by stretching treatment in which necking is suppressed, and a superposed film useful as a high-precision viewing angle compensation film can be obtained.

  Examples of the polymer forming the retardation film include norbornene polymers and polycarbonates, polyethersulfone and polysulfone, polyolefins and acrylic polymers, cellulose resins and polyarylate, polystyrene and polyvinyl alcohol, polyvinyl chloride and polyvinylidene chloride. Polymers exhibiting positive birefringence that increase the refractive index in the stretching direction, such as acetate polymers, are preferably used, and may be films formed using one or more of these polymers.

  The length and width of the long polymer film for forming the retardation film can be the same as those for forming the polarizing film described above. The long polymer film can be formed by applying an appropriate film forming method such as a casting film forming method, a casting method such as a roll coating method or a flow coating method, or an extrusion method. From the viewpoint of mass production of a polarizing film or retardation film with little thickness unevenness and alignment distortion unevenness, a film formed by a solution film forming method such as a casting method can be preferably used. In forming the film, various additives including stabilizers, plasticizers, metals, and the like can be blended as necessary.

  In the roll type longitudinal stretching method, stretching under heating of the film is preferable from the viewpoint of stretching processing with little variation, and the heating is, for example, a method using a heating roll, a method of heating an atmosphere, a method of using them together, or the like. An appropriate method can be applied. In this case, the stretching treatment temperature can be based on the conventional one, and is preferably below the melting temperature of the polymer forming the film, especially near the glass transition temperature, particularly above the glass transition temperature.

  The retardation film having a slow axis in the length direction described above may be a film having an optically uniaxial layer A made of a liquid crystalline material instead of or together with the uniaxially stretched film. . The uniaxial layer A can be formed using an appropriate material exhibiting liquid crystallinity such as a nematic liquid crystal, and a layer made of a liquid crystal polymer is particularly preferable from the viewpoint of durability. Such a retardation film can be obtained in an appropriate form such as a film in which the uniaxial layer A is attached to a support film or a film in which the uniaxial layer A is formed.

  An appropriate film can be used for the support film, and there is no particular limitation. The uniaxial layer A can be used as an integrated product with the support film, or can be used as a film molding separated from the support film. In the case of the former support film integral type, the phase difference which arose in the support film by the extending | stretching process etc. can also be utilized. The latter separation method is advantageous when the phase difference generated in the support film due to stretching or the like is inconvenient.

  In the case of the former support film integrated type, a transparent polymer substrate is preferably used as the support film. Incidentally, examples of the polymer forming the substrate include those exemplified for the above-mentioned transparent protective layer and uniaxially stretched retardation film, and liquid crystal polymers.

  The retardation film having a slow axis in the length direction may be a film having a birefringent layer B made of a non-liquid crystalline material having a birefringence of 0.005 or more. Such a retardation film can also be obtained in an appropriate form such as a film in which the birefringent layer B is attached to a support film or a film in which the birefringent layer B is formed. Further, in the case of a form attached to the support film, for example, a composite film having a birefringence layer B on a birefringent polymer film is used as the support film having birefringence. Also good.

  About the said support film and the film molding of the said birefringent layer B, it can apply according to the case where the above-mentioned uniaxial layer A is provided. Moreover, there is no limitation in particular about the birefringent polymer film for forming the said composite film, It can apply to the said support film etc. In that case, the birefringence is appropriately determined by, for example, a biaxial stretching method such as a roll longitudinal stretching method, a tenter transverse stretching method, a simultaneous biaxial stretching method using a total tenter method, or a sequential biaxial stretching method using a roll tenter method. It is possible to provide a desired phase difference characteristic by a simple method.

  Further, the non-liquid crystalline material forming the birefringent layer B is not particularly limited, and an appropriate material can be used. In particular, from the viewpoint of the formability of a birefringent layer having a birefringence of 0.005 or more, polyether ketone, especially polyaryletherketone or polyamide, polyester or polyimide, polyamideimide or polyesterimide, or the like Two or more are preferably used. The birefringence Δn is defined as Δn = (nx + ny) / 2−nz, where nx and ny are the in-plane refractive indices of the layer and nz is the refractive index in the thickness direction.

Specific examples of the above-described polyether ketones, especially polyaryl ether ketones, include those having a repeating unit represented by the following general formula (1) (Japanese Patent Laid-Open No. 2001-49110).

In the general formula (1), X is a halogen, an alkyl group, or an alkoxy group, and the number of X bonds to the benzene ring q, that is, the p-tetrafluorobenzoylene group and the oxyalkylene group are not bonded. The value of the number of substitutions q of hydrogen atoms is an integer of 0-4. R ¹ is a compound (group) represented by the following general formula (2), and m is 0 or 1. Further, n represents the degree of polymerization, and preferably 2 to 5000, and more preferably 5 to 500.

  Examples of the halogen as X in the general formula (1) include a fluorine atom, a bromine atom, a chlorine atom and an iodine atom, and a fluorine atom is particularly preferable. Examples of the alkyl group include linear or branched alkyl groups having 1 to 6 carbon atoms such as methyl group, ethyl group, propyl group, isopropyl group, and butyl group. A halogenated alkyl group such as a medium methyl group, an ethyl group, or a trifluoromethyl group thereof is preferable.

  Furthermore, examples of the alkoxy group include linear or branched alkoxy groups having 1 to 6 carbon atoms such as a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, and a butoxy group. In particular, a halogenated alkoxy group such as a methoxy group, an ethoxy group, or a trifluoromethoxy group thereof is preferable. In the above, X is particularly preferably a fluorine atom.

  On the other hand, in the group represented by the general formula (2), X ′ is a halogen, an alkyl group or an alkoxy group, and the value of the number of bonds q ′ of X ′ to the benzene ring is an integer of 0 to 4. . Examples of the halogen, alkyl group or alkoxy group as X ′ include the same as those described above for X.

  Preferred X ′ is a fluorine atom, a methyl group or an ethyl group, a halogenated alkyl group such as trifluoromethyl group, a methoxy group or an ethoxy group, or a halogenated alkoxy group such as trifluoromethoxy group. A fluorine atom is preferred.

  In the general formula (1), X and X ′ may be the same or different. Moreover, based on the fact that q or q ′ is 2 or more in general formulas (1) and (2), two or more X or X ′ present in the molecule may be the same or different from each other. It may be.

Particularly preferred R ¹ is a group represented by the following general formula (3).

In the general formulas (2) and (3), R ² is a divalent aromatic group, and P is 0 or 1. Examples of the divalent aromatic group include (o, m or p-) phenylene group, naphthalene group, biphenyl group, anthracene group, (o, m or p-) terphenyl group, phenanthrene group, dibenzofuran group, biphenyl. Examples thereof include an ether group, a biphenylsulfone group, and a divalent aromatic group represented by the following formula. In the divalent aromatic group, hydrogen directly bonded to the aromatic ring may be substituted with the halogen, alkyl group or alkoxy group described above.

In the above, preferable divalent aromatic groups (R ² ) are those represented by the following formulae.

  The polyaryl ether ketone represented by the general formula (1) may be composed of the same repeating unit, or may have two or more different repeating units. In the latter case, each repeating unit may exist in a block form or may exist randomly.

Based on the above, preferable polyaryl ether ketones represented by the general formula (1) are those represented by the following general formula (4).

  A preferable polyaryletherketone including a group at the molecular end is represented by the following general formula (5) corresponding to the general formula (1), and corresponds to the general formula (4). Is represented by the following general formula (6). In these, a fluorine atom is bonded to the p-tetrafluorobenzoylene group side in the molecule, and a hydrogen atom is bonded to the oxyalkylene group side.

On the other hand, specific examples of the polyamide or polyester described above include those having a repeating unit represented by the following general formula (7).

  In the general formula (7), B is halogen, an alkyl group having 1 to 3 carbon atoms or a halide thereof, a phenyl group substituted with one or more of them, or an unsubstituted phenyl group. . z is an integer of 0-3.

E is a covalent bond, an alkenyl group having 2 carbon atoms or a halide thereof, CH ₂ group, C (CX ₃ ) ₂ group, CO group, O atom, S atom, SO ₂ group, Si (R) ₂ group, or NR group. X in the C (CX ₃ ) ₂ group is a hydrogen atom or halogen, and R in the Si (R) ₂ group and the NR group is an alkyl group having 1 to 3 carbon atoms or a halide thereof. E is in a meta position or a para position with respect to the carbonyl group or the Y group. Halogen is a fluorine atom, a chlorine atom, an iodine atom or a bromine atom (hereinafter the same in general formula (7)).

  Y is an O atom or an NH group. A is a hydrogen atom, halogen, an alkyl group having 1 to 3 carbon atoms or a halide thereof, a nitro group, a cyano group, a thioalkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms or a halide thereof, aryl Group or a halide thereof, an alkyl ester group having 1 to 9 carbon atoms, an aryl ester group having 1 to 12 carbon atoms or a substituted derivative thereof, or an arylamide group having 1 to 12 carbon atoms or a substituted derivative thereof.

  N is an integer of 0 to 4, p is an integer of 0 to 3, q is an integer of 1 to 3, and r is an integer of 0 to 3. A preferred polyamide or polyester has a repeating unit represented by the following general formula (8), wherein r and q are 1, and at least one of the biphenyl rings is substituted at the 2-position and the 2′-position. Is.

  In the general formula (8), m is an integer of 0 to 3, preferably 1 or 2, and x and y are 0 or 1, and are not 0 at the same time. The other symbols have the same meaning as in the general formula (7), but E is a covalent bond in para orientation with respect to the carbonyl group or Y group.

  In the general formulas (7) and (8), when a plurality of B, E, Y, or A are present in the molecule, they may be the same or different. Similarly, z, n, m, x, and y may be the same or different. In this case, B, E, Y, A, z, n, m, x, and y are determined independently.

  The polyamide or polyester represented by the general formula (7) may be composed of the same repeating unit, or may have two or more different repeating units. In the latter case, each repeating unit may exist in a block form or may exist randomly.

  On the other hand, specific examples of the polyimide described above include, for example, a condensation polymerization product of 9,9-bis (aminoaryl) fluorene and an aromatic tetracarboxylic dianhydride, and are represented by the following general formula (9). And those having one or more repeating units.

  In the general formula (9), R is a hydrogen atom, a halogen, a phenyl group, a phenyl group substituted with 1 to 4 halogens or an alkyl group having 1 to 10 carbon atoms, or 1 to 10 An alkyl group having a carbon atom. Four Rs can be determined independently and can be substituted in the range of 0 to 4. The substituents are preferably those described above, but some of them may be different. Halogen is a fluorine atom, a chlorine atom, an iodine atom or a bromine atom (hereinafter the same in general formula (9)).

  Z is a trisubstituted aromatic group having 6 to 20 carbon atoms. Preferred Z is a pyromellitic group, a polycyclic aromatic group such as a naphthylene group, a fluorenylene group, a benzofluorenylene group or an anthracenylene group or a substituted derivative thereof, or a group represented by the following general formula (10). is there. Examples of the substituent in the substituted derivative of the polycyclic aromatic group include halogen, an alkyl group having 1 to 10 carbon atoms, or a fluorinated product thereof.

In the general formula (10), D is a covalent bond, C (R ² ) ₂ group, CO group, O atom, S atom, SO ₂ group, Si (C ₂ H ₅ ) ₂ group, N (R ³ ) _Two groups or a combination thereof, and m is an integer of 1 to 10. R ² is independently a hydrogen atom or a C (R ⁴ ) ₃ group. R ³ is independently a hydrogen atom, an alkyl group having 1 to about 20 carbon atoms, or an aryl group having about 6 to about 20 carbon atoms. Each R ⁴ is independently a hydrogen atom, a fluorine atom or a chlorine atom.

  Moreover, what has a unit represented by the following general formula (11), (12) as a polyimide other than the above can be mentioned. Among these, polyimide having a unit represented by the general formula (13) is preferable.

  In the general formulas (11), (12), and (13), T and L are halogen, an alkyl group having 1 to 3 carbon atoms or a halide thereof, phenyl substituted by one or more of them. Group or an unsubstituted phenyl group. The halogen is a fluorine atom, a chlorine atom, an iodine atom or a bromine atom (hereinafter the same in general formulas (11), (12) and (13)). z is an integer of 0-3.

G and J are a covalent bond or a bond bond, CH ₂ group, C (CX ₃ ) ₂ group, CO group, O atom, S atom, SO ₂ group, Si (C ₂ H ₅ ) ₂ group, or N ( CH ₃ ) group. X in the C (CX ₃ ) ₂ group is a hydrogen atom or halogen (hereinafter the same in general formulas (11), (12), and (13)).

  A is a hydrogen atom, a halogen, an alkyl group or a halide thereof, a nitro group, a cyano group, a thioalkyl group, an alkoxy group or a halide thereof, an aryl group or a halide thereof, or an alkyl ester group or a substituted derivative thereof.

  R is a hydrogen atom, a substituted phenyl group such as a halogen, a phenyl group or a halide thereof, or a substituted alkyl group such as an alkyl group or a halide thereof. n is an integer of 0 to 4, p is an integer of 0 to 3, and q is an integer of 1 to 3.

  In the general formulas (11), (12), and (13), when a plurality of T, A, R, or L are present in the molecule, they may be the same or different. Also good. Similarly, z, n, and m may be the same or different. In this case, T, A, R, L, z, n, and m are determined independently.

  The polyimides represented by the general formulas (9), (11), (12), and (13) may be composed of the same repeating unit, or have two or more different repeating units. It may be. The different repeating unit may be formed by copolymerizing one or more of acid dianhydrides and / or diamines other than those described above. As the diamine, an aromatic diamine is particularly preferable. When it has the latter different repeating unit, each repeating unit may exist in a block shape or may exist randomly.

  Examples of the acid dianhydride for forming the different repeating units include pyromelt acid dianhydride, 3,6-diphenylpyromelt acid dianhydride, and 3,6-bis (trifluoromethyl) pyromelt acid dianhydride. 3,6-dibromopyromelt acid dianhydride, 3,6-dichloropyromelt acid dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 2,3,3 ′ , 4′-benzophenone tetracarboxylic dianhydride, 2,2 ′, 3,3′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenylcarboxylic dianhydride, bis (2 , 3-dicarbophenyl) methane dianhydride.

  Also, bis (2,5,6-trifluoro-3,4-dicarboxyphenyl) methane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3- Hexafluoropropane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride (4,4′-oxydiphthalic anhydride), bis (3,4-dicarboxyphenyl) sulfone dianhydride (3,3 3 ', 4,4'-diphenylsulfonetetracarboxylic anhydride), 4,4'-[4,4'-isopropylidene-di (p-phenyleneoxy)] bis (phthalic anhydride) is An example of an anhydride is given.

  Furthermore, N, N- (3,4-dicarboxyphenyl) -N-methylamine dianhydride, bis (3,4-dicarboxyphenyl) diethylsilane dianhydride, 2,3,6,7-naphthalene-tetra Naphthalenetetracarboxylic acids such as carboxylic dianhydrides, 1,2,5,6-naphthalene-tetracarboxylic dianhydrides, 2,6-dichloro-naphthalene-1,4,5,8-tetracarboxylic dianhydrides Acid dianhydride, thiophene-2,3,4,5-tetracarboxylic dianhydride and pyrazine-2,3,5,6-tetracarboxylic dianhydride, pyridine-2,3,5,6-tetra Heterocyclic aromatic tetracarboxylic dianhydrides such as carboxylic dianhydrides are also examples of the acid dianhydrides.

  Preferably used acid dianhydrides are 2,2′-dibromo-4,4 ′, 5,5′-biphenyltetracarboxylic dianhydride and 2,2′-dichloro-4,4 ′, 5,5 ′. -Biphenyltetracarboxylic dianhydrides, 2,2'-substituted dianhydrides such as 2,2'-trihalo-substituted dianhydrides, especially 2,2-bis (trifluoromethyl) -4,4 ' , 5,5'-biphenyltetracarboxylic dianhydride is preferred.

  On the other hand, examples of the diamine for forming the different repeating units include (o, m or p-) phenylenediamine, 2,4-diaminotoluene, 1,4-diamino-2-methoxybenzene, 1,4- Benzenediamine such as diamino-2-phenylbenzene, 1,3-diamino-4-chlorobenzene, 4,4′-diaminobiphenyl, 4,4-diaminodiphenylmethane, 2,2-bis (4-aminophenyl) propane, 2 , 2-bis (4-aminophenyl) -1,1,1,1,3,3,3-hexafluoropropane, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 1,3-bis ( 3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) Benzene, and the like.

  4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-bis (3-aminophenoxy) biphenyl, 2,2-bis (4- [4-aminophenoxy) phenyl] propane, 2,2 -Bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 4,4′-diaminodiphenylthioether, 4,4′-diaminodiphenylsulfone 2,2′-diaminobenzophenone, 3,3′-diaminobenzophenone, naphthalenediamine such as 1,8-diaminonaphthalene and 1,5-diaminonaphthalene, 2,6-diaminopyridine and 2,4-diaminopyridine, Heterocyclic aromatic diamines such as 1,4-diamino-S-triazine are also examples of the diamines described above.

  Examples of polyimides that can be preferably used include 2,2′-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride and 4,4′-bis (3,4-dicarboxyphenyl) -2,2-diphenyl. Heat-resistant and solvent-soluble polyimides prepared using aromatic dianhydrides such as propane dianhydride, naphthalenetetracarboxylic dianhydride and bis (3,4-dicarboxyphenyl) sulfone dianhydride It is.

  Examples of diamines include 4,4- (9-fluorenylidene) -dianiline, 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl, and 3,3′-dichloro-4,4′-diamino. Diphenylmethane, 2,2'-dichloro-4,4'-diaminobiphenyl, 2,2 ', 5,5'-tetrachlorobenzidine, 2,2-bis (4-aminophenoxyphenyl) propane, 2,2-bis (4-aminophenoxyphenyl) hexafluoropropane, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, etc. A heat-resistant and solvent-soluble polyimide prepared using an aromatic diamine can be preferably used.

  On the other hand, the above-mentioned polyamideimide or polyesterimide is not particularly limited, and one or more suitable types can be used. Of these, polyamide imides described in JP-A No. 61-162512 and polyester imides described in JP-A No. 64-38472 can be preferably used.

  The molecular weight of the above-described polymer for forming the birefringent layer B is not particularly limited, but it is preferable that the polymer exhibits a solid body at room temperature and is soluble in a solvent. In particular, it is 10,000 to 1,000,000 based on the weight average molecular weight in terms of film strength, prevention of cracking due to expansion and contraction and strain when formed into a film, and solubility in solvents (preventing gelation). 10,000 to 500,000, particularly 50,000 to 200,000 are preferable. The weight average molecular weight is a value measured by gel permeation chromatography (GPC) using polyethylene oxide as a standard sample and a dimethylformamide solvent.

  For the formation of the retardation film, the above-mentioned polyaryletherketone, polyamide, polyester, polyimide, polyamideimide or polyesterimide may be used alone, or two or more of the same may be used in combination. Good. Further, it may be used as a mixture of two or more kinds of solid polymers having different functional groups, such as a mixture of polyaryl ether ketone and polyamide.

  Furthermore, one or two or more suitable polymers other than those described above may be used in combination as long as the orientation of the solid polymer is not significantly reduced. Incidentally, examples of the combined polymer include polyethylene, polypropylene, polystyrene, polymethyl methacrylate, ABS resin and AS resin, polyacetate, polycarbonate, polyamide, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, polyethersulfone, polyketone, polyimide, Examples thereof include thermoplastic resins such as polycyclohexanedimethanol terephthalate, polyarylate, and liquid crystal polymer (including a photopolymerizable liquid crystal monomer).

  Thermosetting resins such as epoxy resins, phenol resins, and novolac resins are also examples of the combined polymer. The amount of the combined polymer used is not particularly limited as long as the orientation is not significantly lowered, but is usually 50% by weight or less, especially 40% by weight or less, particularly 30% by weight or less.

  Formation of the transparent film which becomes the base of the retardation film can be performed by liquefying a solid polymer, developing it, and solidifying the developing layer. In forming the transparent film, various additives composed of stabilizers, plasticizers, metals and the like can be blended as necessary. For liquefaction of the solid polymer, an appropriate method such as a method of heating and melting the thermoplastic solid polymer or a method of dissolving the solid polymer in a solvent to form a solution can be employed.

  Therefore, the development layer can be solidified by cooling the development layer in the former melt and removing the solvent from the development layer and drying in the latter solution. For the drying, one or more of appropriate methods such as a natural drying (air drying) method and a heat drying method, particularly a heat drying method at 40 to 200 ° C. and a vacuum drying method can be adopted. From the viewpoint of suppressing production efficiency and generation of optical anisotropy, a method of applying a polymer solution is preferable.

  Examples of the solvent include chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, trichloroethylene, halogenated hydrocarbons such as tetrachloroethylene, chlorobenzene, and orthodichlorobenzene, phenols such as phenol and parachlorophenol, benzene, toluene, and xylene. Aromatic hydrocarbons such as methoxybenzene, 1,2-dimethoxybenzene, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, 2-pyrrolidone, ketones such as N-methyl-2-pyrrolidone, ethyl acetate And esters such as butyl acetate.

  Also, alcohols such as t-butyl alcohol and glycerin, ethylene glycol and triethylene glycol, ethylene glycol monomethyl ether and diethylene glycol dimethyl ether, propylene glycol and dipropylene glycol and 2-methyl-2,4-pentanediol, dimethylformamide and dimethylacetamide Examples of the solvent include amides such as nitriles such as acetonitrile and butyronitrile, ethers such as diethyl ether, dibutyl ether and tetrahydrofuran, methylene chloride, carbon disulfide, ethyl cellosolve and butyl cellosolve.

  A solvent can be used individually or in mixture of 2 or more types by appropriate combination. From the viewpoint of viscosity suitable for film formation, the solution is preferably a solution in which 2 to 100 parts by weight, especially 5 to 50 parts by weight, especially 10 to 40 parts by weight of the solid polymer is dissolved with respect to 100 parts by weight of the solvent.

  For example, spin coating method, roll coating method, flow coating method, printing method, dip coating method, casting film forming method, casting method such as bar coating method and gravure printing method, extrusion method, etc. It is possible to adopt an appropriate film forming method such as. In particular, a solution film forming method such as a casting method can be preferably applied from the viewpoint of mass production of a film having little thickness unevenness and alignment strain unevenness.

  The birefringent layer B described above has a maximum refractive index in the plane of nx, a refractive index in the direction perpendicular to the nx direction in the plane is ny, and a refractive index in the layer thickness direction is nz, where nx> ny>. Those having a relationship of nz are preferable from the viewpoint of achieving a liquid crystal display with good contrast at a wide viewing angle. A retardation film in which the birefringent layer B has a relationship of nx> ny> nz, or a superimposed film using the same is particularly preferably used for a VA mode or OCB mode liquid crystal display device.

  The above relationship of nx> ny> nz can be achieved, for example, by subjecting the film to a stretching process or / and a shrinking process, and the stretching process can be performed, for example, as a stretching process. For the stretching treatment, one or two or more of appropriate methods such as a biaxial stretching method such as a sequential method or a simultaneous method, a uniaxial stretching method such as a free end method or a fixed end method can be applied. The stretching treatment temperature can be based on the conventional one, and is generally in the vicinity of the glass transition temperature of the solid polymer forming the transparent film, especially above the glass transition temperature or below the melting temperature.

  On the other hand, the shrinkage treatment can be performed by, for example, a method in which a transparent film is applied and formed on a base material, and a shrinkage force is applied using a dimensional change accompanying a temperature change of the base material. In that case, it is also possible to use a base material imparted with a shrinking ability such as a heat-shrinkable film. At that time, it is desirable to control the shrinkage rate using a stretching machine or the like.

  A preferred method for producing a retardation film having a birefringent layer B is to develop a solid polymer dissolved in a solvent and liquefied on a support film, and then dry, and stretch or apply a transparent film or coating film made of the solidified product. In this method, one or both of the shrinkage treatments are performed to orient the molecules in the plane, and the characteristics of nx> ny> nz are imparted. According to this method, it can process in the state which supported the transparent film with the support film, is excellent in manufacturing efficiency, processing precision, etc., and can also manufacture continuously.

  The retardation film may be one in which the support film is integrated with a transparent film, or may be a transparent film separated from the support film. In the case of the former support film integrated type, the phase difference which arose in the support film by the extending | stretching process etc. can also be utilized as a phase difference in a phase difference film, and this is a composite film. The latter separation method is advantageous when the phase difference generated in the support film due to stretching or the like is inconvenient. In addition, as a support film in the said composite film, what consists of said solid polymer is also used.

  Further, polymers described in JP-A No. 2001-343529 (WO01 / 37007), for example, (1) a thermoplastic resin having a substituted or / and unsubstituted imide group in the side chain, and (2) a substitution or / In addition, a resin composition containing the above 1, 2 with a thermoplastic resin having an unsubstituted phenyl group and a nitrile group can also be used for forming a support film. Such a film can also be used to support the optically uniaxial layer A made of the liquid crystalline material described above.

  Incidentally, specific examples of the resin composition include a resin composition containing an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer. The support film can be obtained as a film made of a mixed extruded product of the resin composition. The polymer can also be used to form a transparent film.

  From the viewpoint of optical compensation effect and the like, preferable retardation characteristics in a retardation film having a slow axis in the length direction are: nx, ny for the in-plane refractive index, nz for the refractive index in the thickness direction, and d for the thickness. , (Nx−ny) d = Δn · d = Re and (nx−nz) d = Rz indicate Re of 5 to 1000 nm, especially 10 to 800 nm, especially 20 to 500 nm. Rz is preferably 5 to 5000 nm, more preferably 10 to 3000 nm, and particularly preferably 30 to 1000 nm.

  The sizes of Re and Rz described above are the type of polymer, the forming method of the developing layer such as the coating method of the liquefied material, the solidifying method of the developing layer such as the drying conditions, the thickness of the film to be formed, and the stretching condition Etc. can be controlled.

  The thickness of the retardation film is generally 5 to 300 μm, especially 10 to 200 μm, and particularly 20 to 150 μm. The thickness of the birefringent layer B provided as a coating film on the support film is generally 0.5 to 30 μm, in particular 1 to 25 μm, particularly 2 to 20 μm.

  When laminating the polarizing film and the retardation film, the retardation film can also serve as the transparent protective layer in the polarizing film described above. In that case, the superimposed film, and thus the liquid crystal display device can be made thinner.

  An adhesive layer or a pressure-sensitive adhesive layer can be used as necessary in forming the superimposed film, that is, in laminating the polarizing film and one or more retardation films. Such a superposed film can be preferably used, for example, for compensation of phase difference due to cell birefringence for the purpose of, for example, increasing the viewing angle of a liquid crystal cell or improving contrast.

  In practical use of the polarizing film or the superimposed film, for example, an adhesive layer or an adhesive layer can be provided on one side or both sides for the purpose of bonding with another member such as a liquid crystal cell. For the formation of the adhesive layer, for example, a transparent adhesive using an appropriate polymer such as an acrylic polymer, a silicone polymer, polyester, polyurethane, polyether, or synthetic rubber can be used. In particular, acrylic pressure-sensitive adhesives are preferred from the viewpoints of optical transparency, pressure-sensitive adhesive properties, weather resistance, and the like.

  Appropriate addition of fillers and pigments such as natural and synthetic resins, glass fibers and glass beads, metal powders and other inorganic powders, colorants and antioxidants as necessary An agent can also be blended. Moreover, it can also be set as the adhesion layer which contains transparent fine particles and shows light diffusibility. When the pressure-sensitive adhesive layer is exposed on the surface, it is preferable to temporarily attach a separator or the like to prevent contamination of the pressure-sensitive adhesive layer surface until it is put to practical use.

  The formation of the superimposed film can be performed by a method of sequentially laminating separately in the manufacturing process of the liquid crystal display device or the like, but by laminating in advance, the liquid crystal display device or the like has excellent quality stability and lamination workability. There is an advantage that manufacturing efficiency can be improved.

  The polarizing film or the overlapping film according to the present invention can be preferably used for forming various display devices such as a liquid crystal display device. In the application, one of other optical layers such as a reflection plate, a semi-transmission reflection plate, a brightness enhancement film, another retardation plate, a diffusion control film, a polarization scattering film, etc. is passed through an adhesive layer or an adhesive layer as necessary. It can also be used as an optical member formed by laminating layers or two or more layers. For the lamination, an appropriate bonding means such as the above-mentioned adhesive layer can be used.

  The said reflecting plate is for providing it in a polarizing film and forming a reflective polarizing film. A reflective polarizing film is usually disposed on the back side of a liquid crystal cell to form a liquid crystal display device (reflective liquid crystal display device) of a type that reflects incident light from the viewing side (display side) and displays it. Therefore, there is an advantage that it is possible to omit a built-in light source such as a backlight and to easily reduce the thickness of the liquid crystal display device.

  The reflective polarizing film 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 film via a transparent protective layer or the like as necessary. Specific examples thereof include those in which a foil or a vapor deposition film made of a reflective metal such as aluminum is attached to one side of a transparent protective layer that is matted as necessary.

  The reflective layer may be a light diffusion type. The light diffusion type reflective layer can be obtained, for example, by a method of forming a reflective layer reflecting the fine concavo-convex structure on a transparent protective layer containing transparent fine particles and having a surface having a fine concavo-convex structure. A reflective layer having a fine surface irregular structure has the advantage of diffusing incident light by irregular reflection, preventing directivity and glaring appearance, and suppressing uneven brightness. The reflective layer reflecting the fine concavo-convex structure is formed by attaching a metal reflective layer on the fine concavo-convex structure by an appropriate method such as a vacuum deposition method, an ion plating method, a sputtering method, or a plating method, or a plating method. Can be formed.

  In addition, it can replace with the system attached directly to the transparent protective layer of an above-described polarizing film, and a reflection layer can also be provided as a reflection sheet etc. which attaches a reflection layer to an appropriate film. The reflective layer made of metal is used in a state where the reflective surface is covered with a film, a polarizing film, etc., to prevent a decrease in reflectance due to oxidation, and in turn, to maintain the initial reflectance for a long period of time. It is preferable from the viewpoint of avoiding the above.

  Further, the reflective layer may be a semi-transmissive type made of a half mirror or the like that reflects and transmits light. A transflective polarizing film is also usually provided on the back side of a liquid crystal cell, and when using a liquid crystal display device etc. in a relatively bright atmosphere, display is achieved by reflecting incident light from the viewing side (display side). In a relatively dark atmosphere, a display device or the like that achieves display using a built-in light source such as a backlight disposed on the back side of the transflective polarizing film is formed. Therefore, the transflective polarizing film can save energy by using a light source such as a backlight in a bright atmosphere, and is useful for forming a display device that can be used with a built-in light source even in a relatively dark atmosphere.

  On the other hand, the above-described brightness enhancement film is used for the purpose of improving brightness by suppressing absorption loss due to the polarizing film. An appropriate film can be used as the brightness enhancement film. By way of example, it exhibits the characteristic of transmitting linearly polarized light with a predetermined polarization axis and reflecting other light, such as a dielectric multilayer thin film or a multilayer laminate of thin film films having different refractive index anisotropy ( For example, “D-BEF” manufactured by 3M Co., Ltd.) may be mentioned.

  Also, a cholesteric liquid crystal layer, in particular an oriented film of a cholesteric liquid crystal polymer, or a film in which the oriented liquid crystal layer is supported on a film substrate (eg, Nitto Denko, “PCF350”, Merck, “Transmax”, etc.) In addition, a brightness enhancement film made of a material that reflects either the left-handed or the right-handed circularly polarized light and transmits the other light may be used. In the case of a cholesteric liquid crystal system, it can be used in combination with a quarter wavelength plate as necessary for the purpose of converting circularly polarized light into linearly polarized light.

  Further, as the retardation plate, in addition to the above-mentioned quarter wavelength plate, various positions such as a stretched film of various polymers by an appropriate method such as uniaxial or biaxial, a polymer film subjected to Z-axis alignment treatment, a liquid crystalline polymer layer, etc. Those having a phase difference can be used. The diffusion control film is used for the purpose of controlling glare related to viewing angle and resolution, scattered light, and the like, and an optical functional film utilizing diffusion, scattering, and / or refraction is used. Furthermore, the polarization scattering film is a film in which a scattering substance is contained in the film so that the polarized light has scattering anisotropy depending on the vibration direction, and is used for controlling the polarization.

  The above-described optical member in which two or more optical layers are laminated can be formed by a method of separately laminating sequentially in the manufacturing process of a liquid crystal display device or the like. The product has the advantage of improving the production efficiency of the liquid crystal display device and the like by being excellent in the stability of quality and the assembly workability.

  The optical member can be provided with a pressure-sensitive adhesive layer or an adhesive layer on a necessary surface for adhering to another optical layer or another member such as a liquid crystal cell. The adhesive layer can be formed according to the above. In particular, the moisture absorption rate is low in terms of prevention of foaming and peeling phenomena due to moisture absorption, deterioration of optical properties due to thermal expansion differences, prevention of liquid crystal cell warpage, and the formation of high-quality and durable display devices. An adhesive layer that is low and excellent in heat resistance can be preferably used. The above-mentioned pressure-sensitive adhesive layer or adhesive layer may be blended with transparent fine particles to exhibit light diffusibility.

  If the adhesive layer or adhesive layer provided on the polarizing film, superimposed film, or optical member is exposed on the surface, temporarily cover the adhesive layer with a separator for the purpose of preventing contamination until the adhesive layer is put to practical use. It is preferable. The separator is obtained by, for example, a method of providing a coating layer with an appropriate release agent such as silicone-based, long-chain alkyl-based, fluorine-based, molybdenum sulfide, or the like on an appropriate thin leaf made of the above support film or paper. Can do.

  Each layer such as a polarizing film or retardation film that forms the above-described superimposed film or optical member, a transparent protective layer, an adhesive layer, and the like are, for example, salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, Those having an ultraviolet absorbing ability by an appropriate method such as a method of treating with an ultraviolet absorber such as a nickel complex salt compound may be used.

  The polarizing film, the superimposing film, and the optical member according to the present invention can be preferably used for forming various devices such as a liquid crystal display device. For example, a reflective film or a semi-transmissive film in which a polarizing film is disposed on one side or both sides of a liquid crystal cell. It can be used to form a liquid crystal display device such as a mold or a transmission / reflection type.

  That is, a liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, a polarizing film or a superposition film, and an illumination system as necessary, and incorporating a drive circuit. There is no particular limitation except that a polarizing film, a superimposing film, or an optical member according to the invention is provided on at least one side outside the liquid crystal cell, and can be based on the conventional one. When placed on both sides of the liquid crystal cell, it is advantageous to use a combination of a polarizing film having an absorption axis in the width direction and a polarizing film having an absorption axis in the length direction from the viewpoint of forming a large screen. is there.

  Therefore, a liquid crystal display device in which a superposed film is arranged on one or both sides of the liquid crystal cell, a liquid crystal display device using a backlight or a front light in an illumination system, or a transmissive type or reflective type using a reflective plate or a semi-transmissive reflective plate. An appropriate liquid crystal display device such as a mold or a reflection / transmission mold can be formed. It is more preferable to arrange the superimposed film so that the retardation film is positioned between the liquid crystal cell on the viewing side or / and the back side and the polarizing film, particularly between the polarizing film on the viewing side. . In the arrangement, the optical member described above can also be used.

  In the above, the liquid crystal cell forming the liquid crystal display device is arbitrary, for example, an active matrix driving type represented by a thin film transistor type, a simple matrix driving type represented by a TN type or STN type, a VA type or an OCB type. An appropriate type of liquid crystal cell such as an IPS type may be used. In particular, it can be preferably used for a type in which a polarizing film is arranged so that its absorption axis is parallel to the side of the liquid crystal cell, such as VA type and IPS type.

In the above description, the components for forming the liquid crystal display device may be laminated and integrated, or may be in a separated state. In forming the liquid crystal display device, for example, an appropriate optical element such as a prism array sheet, a lens array sheet, a light diffusing plate, or a protective plate can be appropriately disposed. Such an element can also be used for the formation of a liquid crystal display device in the form of the above-mentioned optical member laminated with a superimposed film.
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

  The film is successively drawn out from a roll of a film of polyvinyl alcohol (PVA) having a polymerization degree of 2400, a thickness of 75 μm, a width of 0.3 m, and a length of 500 m, and the width direction is 120 ° C. with a tenter stretching machine. The film was stretched 5 times. Next, the stretched film was immersed for 1 minute in a dye bath at 30 ° C. containing iodine and potassium iodide under suppression of shrinkage in the length direction, and then immersed in a 5% aqueous potassium iodide solution at 30 ° C. for 5 seconds. Next, the film was dried at 45 ° C. for 7 minutes in a state of being fixed so as to suppress the shrinkage of the film, and the obtained film was cut into a width of 1 m, and then a triacetyl cellulose (TAC) film via a PVA water-soluble adhesive on both sides thereof. Were bonded together to obtain a TD polarizing film having a three-layer structure consisting of a TAC film / TD polarizer / TAC film and wound into a roll.

Comparative Example 1
Rolls are made by sequentially feeding the film from a roll-shaped wound body made of PVA having a polymerization degree of 2400, a thickness of 75 μm, a width of 1.2 m, and a length of 500 m, and immersed in pure water at 30 ° C. for 1 minute. The film was stretched 2.5 times in the length direction by the longitudinal stretching method. Next, the stretched film was stretched 1.2 times in the length direction while immersed in a dye bath at 30 ° C. containing iodine and potassium iodide for 1 minute, and then in a bath at 60 ° C. made of 4% boric acid aqueous solution. The film was stretched 2 times in the length direction while immersed in 2 minutes, then immersed in 5% aqueous potassium iodide solution at 30 ° C. for 5 seconds and dried at 45 ° C. for 7 minutes, and the resulting film was cut into a width of 1 m. A TAC film was bonded to both sides according to Example 1 to obtain a three-layer MD polarizing film composed of a TAC film / MD polarizer / TAC film and wound into a roll.

Reference example 1
The film is successively drawn out from a roll-shaped wound body of a film of norbornene-based resin film (manufactured by JSR, Arton) having a thickness of 100 μm, a width of 1.2 m, and a length of 500 m. After stretching 1.3 times in the length direction at 0 ° C., it was cut into a width of 1 m to obtain a (MD) retardation film and wound into a roll. This is that Re is 100 nm, Re distribution in the width direction (variation: difference between maximum and minimum values, the same applies hereinafter) is 5 nm, and the distribution of slow axis (length direction) is 1 degree. . Re (and Rz below) was calculated from the refractive index measured with KOBRA-21ADH manufactured by Oji Scientific Instruments (hereinafter the same).

Reference example 2
The Arton film was stretched 1.5 times in the width direction at 175 ° C. with a tenter stretching machine, and a (TD) retardation film was obtained according to Reference Example 1 and wound into a roll. In this case, Re was 100 nm, the distribution of Re in the width direction was 8 nm, and the distribution of the slow axis (width direction) was 2.5 degrees.

Reference example 3
A film is sequentially drawn out from a roll-shaped wound body of a TAC film having a thickness of 50 μm, a width of 1.2 m, and a length of 500 m, and 2,2′-bis (3,4-dicarboxyphenyl) hexafluoropropane is formed on the film. And a 2 wt-% cyclohexanone solution of polyimide synthesized from 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl and sequentially dried at 120 ° C. for 10 minutes and a polyimide layer having a thickness of 6 μm The film was stretched 1.05 times in the length direction at 150 ° C. by a roll type longitudinal stretching method, and then cut into a width of 1 m to obtain a (MD) retardation film and wound into a roll. This was Re of 50 nm, Rz of 280 nm, Re distribution in the width direction was 2 nm, and slow axis (length direction) distribution was 0.5 degree.

Reference example 4
A (TD) retardation film was obtained according to Reference Example 3 except that the film was stretched 1.1 times in the width direction at 150 ° C. with a tenter stretching machine, and wound into a roll. This was Re 50 nm, Rz 290 nm, Re distribution in the width direction was 7 nm, and slow axis (width direction) distribution was 1.5 degrees.

Reference Example 5
The film is sequentially drawn out from a roll-shaped wound body of a film having a thickness of 100 μm, a width of 1.3 m, and a length of 1000 m made of a norbornene-based resin film (Zeonor, manufactured by Nippon Zeon Co., Ltd.). The film was stretched 1.1 times in the length direction at 140 ° C., and then cut into a width of 1 m to obtain a (MD) retardation film and wound into a roll. This was Re of 100 nm, the distribution of Re in the width direction was 4 nm, and the distribution of the slow axis (length direction) was 1.6 degrees.

Reference Example 6
The film is sequentially drawn out from a roll-shaped wound body of a film having a thickness of 100 μm, a width of 1.2 m, and a length of 500 m made of a polycarbonate resin film (manufactured by Kaneka Chemical Co., Ltd., PF film), and the roll-type longitudinal stretching method. The film was stretched 1.15 times in the length direction at 150 ° C. and then cut into a width of 1 m to obtain a (MD) retardation film and wound into a roll. This was Re of 100 nm, the distribution of Re in the width direction was 5 nm, and the distribution of the slow axis (length direction) was 1.8 degrees.

Reference Example 7
The film is successively drawn out from a roll-shaped wound body of a film of cellulose acetate propionate resin film (manufactured by Kaneka Chemical Co., Ltd., KA film) having a thickness of 100 μm, a width of 1.2 m, and a length of 500 m. The film was stretched 1.5 times in the length direction at 150 ° C. by a longitudinal stretching method, and then cut into a width of 1 m to obtain a (MD) retardation film and wound into a roll. This was Re of 100 nm, the distribution of Re in the width direction was 5 nm, and the distribution of the slow axis (length direction) was 1.2 degrees.

  While sequentially rolling out the (TD) polarizing film of Example 1 and the (MD) retardation film of Reference Example 1 from the roll-shaped wound body, the length directions are matched and laminated through an acrylic adhesive layer. A superposed film in which the absorption axis of the polarizing film and the slow axis of the retardation film were orthogonal to each other was continuously obtained.

  While sequentially rolling out the (TD) polarizing film of Example 1 and the (MD) retardation film of Reference Example 3 from the roll-shaped wound body, the length directions are matched and laminated via an acrylic adhesive layer. A superposed film in which the absorption axis of the polarizing film and the slow axis of the retardation film were orthogonal to each other was continuously obtained.

  While sequentially rolling out the (TD) polarizing film of Example 1 and the (MD) retardation film of Reference Example 5 from the roll-shaped wound body, the length directions thereof correspond to each other and laminated through an acrylic adhesive layer. A superposed film in which the absorption axis of the polarizing film and the slow axis of the retardation film were orthogonal to each other was continuously obtained.

  While sequentially rolling out the (TD) polarizing film of Example 1 and the (MD) retardation film of Reference Example 6 from the roll-shaped wound body, the length direction is made to correspond to each other and laminated through an acrylic adhesive layer. A superposed film in which the absorption axis of the polarizing film and the slow axis of the retardation film were orthogonal to each other was continuously obtained.

  While sequentially rolling out the (TD) polarizing film of Example 1 and the (MD) retardation film of Reference Example 7 from the roll-shaped wound body, the length directions thereof correspond to each other and laminated through an acrylic adhesive layer. A superposed film in which the absorption axis of the polarizing film and the slow axis of the retardation film were orthogonal to each other was continuously obtained.

Comparative Example 2
While sequentially rolling out the (MD) polarizing film of Comparative Example 1 and the (TD) retardation film of Reference Example 2 from the roll-shaped wound body, the length directions are matched and laminated through an acrylic adhesive layer. A superposed film in which the absorption axis of the polarizing film and the slow axis of the retardation film were orthogonal to each other was continuously obtained.

Comparative Example 3
While sequentially rolling out the (MD) polarizing film of Comparative Example 1 and the (TD) retardation film of Reference Example 4 from the roll-shaped wound body, the length directions are matched and laminated through an acrylic adhesive layer. A superposed film in which the absorption axis of the polarizing film and the slow axis of the retardation film were orthogonal to each other was continuously obtained.

Comparative Example 4
A film having a predetermined size is cut out from the (MD) polarizing film of Comparative Example 1 and the (MD) retardation film of Reference Example 1, and the absorption axis of the polarizing film and the slow axis of the retardation film are orthogonal to each other through an acrylic adhesive layer. And laminated to obtain a superimposed film.

Comparative Example 5
While sequentially rolling out the (MD) polarizing film of Comparative Example 1 and the (MD) retardation film of Reference Example 5 from the roll-shaped wound body, the length directions are matched and laminated through an acrylic adhesive layer. A superposed film in which the absorption axis of the polarizing film and the slow axis of the retardation film are parallel was continuously obtained.

Comparative Example 6
While sequentially rolling out the (MD) polarizing film of Comparative Example 1 and the (MD) retardation film of Reference Example 6 from the roll-shaped wound body, the length directions are matched to each other and laminated through an acrylic adhesive layer. A superposed film in which the absorption axis of the polarizing film and the slow axis of the retardation film are parallel was continuously obtained.

Comparative Example 7
While sequentially rolling out the (MD) polarizing film of Comparative Example 1 and the (MD) retardation film of Reference Example 7 from the roll-shaped wound body, the length directions are matched and laminated through an acrylic adhesive layer. A superposed film in which the absorption axis of the polarizing film and the slow axis of the retardation film are parallel was continuously obtained.

Evaluation test 1
The superposed film having an effective width of 1 m obtained in Examples and Comparative Examples is used in the following combination so that the absorption axis of the polarizing film is orthogonal to the viewing side and the back side of the VA liquid crystal cell having an aspect ratio of 16: 9. We investigated the maximum size of the screen that can be formed when placed.

The results are shown in the following table.

Arrangement maximum screen size
Viewing side Back side
Example 1 Comparative Example 2 Example 2 80 inches
Example 2 Comparative Example 3 Example 3 80 inches
Example 3 Comparative Example 2 Comparative Example 2 45 inches
Example 4 Comparative Example 3 Comparative Example 3 45 inches
Example 5 Comparative Example 2 Comparative Example 4 45 inches

Evaluation test 2
The superposed film of a predetermined size obtained in Examples and Comparative Examples is disposed on the back side of a commercially available VA liquid crystal cell, and the polarizing film of Example 1 is orthogonal to the back side on the viewing side. Thus, a liquid crystal display device was formed, and the visibility of the display was examined.

The results are shown in the following table.
Arrangement visibility
Example 6 Example 2 Good Good
Example 7 Example 3 Good Good
Example 8 Comparative Example 2 Unevenness
Example 9 Comparative Example 3 Uneven
Example 10 Example 4 Good Good
Example 11 Example 5 Good Good
Example 12 Example 6 Good Good
Example 13 Comparative Example 5 Unevenness
Example 14 Comparative Example 6 Uneven
Example 15 Comparative Example 7 Uneven

  From Examples 1 to 5 above, it can be seen that the screen can be enlarged by using the superimposed films (Examples 1 and 2) using the polarizing film according to the present invention. Further, from Examples 6 to 12, it can be seen that the superimposed films according to the present invention (Examples 6, 7, and 10 to 12) can achieve good display with little variation in the slow axis in the retardation film. Further, it can be seen from Examples 10 to 15 that good display can be achieved by making the absorption axis of the polarizing film and the slow axis of the retardation film orthogonal to each other as in the superposed films (Examples 10 to 12) according to the present invention.

Claims (11)

A polarizing film comprising a long polymer film, the film containing a dichroic substance, and having an absorption axis in the width direction. The polarizing film according to claim 1, wherein the polarizing film is stretched in the width direction by dry heating, or contracted in the length direction. 3. The polarizing film according to claim 1, wherein iodine is dyed with an aqueous solution containing iodine after stretching in the width direction or after stretching in the width direction and contraction in the length direction. 4. The polarizing film according to claim 3, wherein an elongated polymer film is coated with an aqueous solution containing iodine to stain iodine. A polarizing film according to one of claims 1 to 4 and a retardation film comprising a long polymer film and having a slow axis in the length direction are laminated in correspondence with the length directions of the long films. Superimposed film. 6. The superimposed film according to claim 5, wherein the retardation film has an optically uniaxial layer made of a uniaxially stretched film or a liquid crystalline material. The superimposed film according to claim 5 or 6, wherein the retardation film has a birefringent layer made of a non-liquid crystalline material, and the birefringence of the non-liquid crystalline material is 0.005 or more. The superimposed film according to claim 7, wherein the retardation film is a composite film in which a birefringent layer is provided on a birefringent polymer film. The superimposed film according to claim 7 or 8, wherein the birefringent layer is composed of one or more of polyetherketone, polyamide, polyester, polyimide, polyamideimide, or polyesterimide. The birefringent layer according to any one of claims 7 to 9, wherein the birefringent layer has a maximum refractive index in the plane of nx, a refractive index in the direction perpendicular to the nx direction in the plane is ny, and a refractive index in the layer thickness direction is nz , Nx> ny> nz. The liquid crystal display device formed by arrange | positioning the polarizing film of one of Claims 1-4, or the superimposition film of one of Claims 5-10 outside a liquid crystal cell.