JP4908102B2 - Retardation film, polarizing plate and liquid crystal display device - Google Patents

Description

  The present invention belongs to the technical field of retardation films, polarizing plates and liquid crystal display devices, and particularly to the technical field of vertical alignment type liquid crystal display devices, retardation films and polarizing plates used therefor.

  A liquid crystal display device usually has a liquid crystal cell and a polarizing plate. The polarizing plate generally has a protective film and a polarizing film. The polarizing plate can be obtained by, for example, dyeing a polarizing film made of a polyvinyl alcohol film with iodine, stretching, and laminating protective films on both sides. In the transmissive liquid crystal display device, the polarizing plate is attached to both sides of the liquid crystal cell, and one or more optical compensation sheets may be disposed. In a reflective liquid crystal display device, a reflector, a liquid crystal cell, one or more optical compensation sheets, and a polarizing plate are usually arranged in this order. The liquid crystal cell has liquid crystal molecules, two substrates for enclosing the liquid crystal molecules, and an electrode layer for applying a voltage to the liquid crystal molecules. The liquid crystal cell performs ON / OFF display depending on the alignment state of liquid crystal molecules, and can be applied to both a transmission type and a reflection type, TN (Twisted Nematic), IPS (In-Plane Switching), OCB (Optically Compensatory). Display modes such as Bend, VA (Vertically Aligned), and ECB (Electrically Controlled Birefringence) have been proposed.

  Among such liquid crystal display devices, for applications that require high display quality, a nematic liquid crystal material having a positive dielectric anisotropy is used and a 90-degree twisted nematic liquid crystal display device (hereinafter referred to as TN) driven by a thin film transistor. Mode) is mainly used. However, although the TN mode has excellent display characteristics when viewed from the front, the contrast is reduced when viewed from an oblique direction, or gradation inversion that reverses the brightness in gradation display occurs. There is a viewing angle characteristic that the display characteristic is deteriorated, and this improvement is strongly demanded.

  In recent years, as a liquid crystal display device method for improving the viewing angle characteristics, a nematic liquid crystal material having negative dielectric anisotropy is used, and the major axis of the liquid crystal molecules is set in a direction substantially perpendicular to the substrate without applying a voltage. A vertical alignment nematic liquid crystal display device (hereinafter referred to as VA mode) in which alignment is performed and driven by a thin film transistor has been proposed (see Patent Document 1). This VA mode has the same excellent display characteristics as the TN mode when viewed from the front. Further, when a viewing angle compensation phase difference film is applied to a VA mode liquid crystal display device, viewing angle characteristics when viewed from an oblique direction are improved, and wide viewing angle characteristics are exhibited. In the VA mode, a wide viewing angle characteristic can be obtained by using two negative uniaxial retardation films having an optical axis in a direction perpendicular to the film surface, above and below the liquid crystal cell. Furthermore, it is also known that a wider viewing angle characteristic can be realized by using a uniaxially oriented retardation film having a positive refractive index anisotropy with an in-plane retardation value of 50 nm (Non-patent Document 1). reference).

  However, increasing the number of retardation films increases the production cost, and tends to cause a decrease in yield because a large number of films are bonded together. Furthermore, since a plurality of films are used, the thickness increases, which may be disadvantageous for thinning the display device. Moreover, since an adhesive layer is used for lamination | stacking of a stretched film, an adhesive layer shrink | contracts by a temperature / humidity change, and defects, such as peeling and curvature between films, may generate | occur | produce.

  As a method for improving these, a method of reducing the number of retardation films (see Patent Document 2) and a method of using a cholesteric liquid crystal layer for optical compensation (see Patent Document 3) are disclosed. However, even in these methods, it is necessary to attach at least a plurality of films, which is insufficient in terms of thinning the liquid crystal display device and reducing production costs.

Further, for the purpose of improving the above problems, a method using a discotic liquid crystalline compound (see Patent Document 4) has been proposed. However, in the method described in Patent Document 4, it is difficult to continuously form an optically anisotropic layer on a long support, and productivity is inferior. Furthermore, a method for solving this problem is disclosed in Patent Document 5 (see Patent Document 5). However, the method described in Patent Document 5 also has problems such as coating unevenness because the coating film thickness increases in order to obtain necessary optical characteristics (particularly, Rth value).
Furthermore, Patent Document 6 discloses a method for improving coating unevenness by employing an optically anisotropic layer having an absolute value of refractive index anisotropy in a specific range.
However, the above method is not at a level that can satisfy the display characteristics of the liquid crystal display device.
Japanese Patent Laid-Open No. 2-176625 JP-A-11-95208 JP-A-11-95208 JP-A-11-352328 JP 2000-304931 A JP 2005-128050 A SID 97 DIGEST Pages 845-848

An object of the present invention is to provide a retardation film for use in a liquid crystal display device in which a liquid crystal cell is accurately optically compensated and can be dealt with even if the number of films to be bonded is reduced, that is, a thin layer can be formed. And a liquid crystal display device.
In addition, the present invention contributes to the reduction of light leakage and color change when observed from an oblique direction during black display of a liquid crystal display device, particularly a VA mode liquid crystal display device, and is stably manufactured by a simple method. It is an object of the present invention to provide a possible retardation film and polarizing plate.
In addition, the present invention has good display characteristics when observed from the front direction, and also has good display characteristics when observed from the oblique direction, specifically, when observed from the oblique direction during black display. It is an object of the present invention to provide a liquid crystal display device, particularly a VA mode liquid crystal display device, in which light leakage and color change are reduced.

  As a result of intensive studies by the inventor in order to solve such problems, all of the conventional retardation films in which a support made of a polymer film or the like and an optically anisotropic layer are combined mainly have characteristics of the optically anisotropic layer. However, in order to solve the above problems, it has been found that the optical properties of the support must also be studied. As a result of further studies, the use of a retardation film made of a predetermined material and having a support in which Re, Rth, and chromatic dispersion characteristics satisfy a predetermined relationship improves the display characteristics of the liquid crystal display device. It has been found that the display characteristics (display characteristics in the oblique direction as well as the front direction) reach a satisfactory level.

Specifically, means for solving the above problems are as follows.
(1) A retardation film having a support and at least one optically anisotropic layer,
The support is composed of a cellulose acylate film containing at least one acrylic polymer, the front retardation Re and the thickness direction retardation Rth satisfy the following formula [1], and the wavelength dispersibility thereof is represented by the following formula [ 2]; and the retardation film satisfying the following formula [3] in which the front retardation Re and the retardation Rth in the thickness direction of the retardation film satisfy the following formula [4]:
[1] 0 ≦ Re (630) ≦ 10 and | Rth (630) | ≦ 25
[2] | Re (400) −Re (700) | ≦ 10 and −35 ≦ Rth (400) −Rth (700) ≦ 60
[3] 0 ≦ Re (550) ≦ 10 and 100 ≦ Rth (550) ≦ 300
[4] 1.04 ≦ Rth (450) / Rth (550) ≦ 1.30
In the formula, Re (λ) is represented by Re (λ) = (nx−ny) × d, and represents the front retardation value (unit: nm) at the wavelength λnm, and Rth (λ) is Rth (λ) = It is represented by {(nx + ny) / 2−nz} × d, and represents a retardation value (unit: nm) in the film thickness direction at a wavelength λ nm, where nx is a refractive index in the slow axis direction in the film plane, ny Is the refractive index in the fast axis direction in the film plane, nz is the refractive index in the thickness direction of the film, and d is the thickness (nm) of the film.
(2) The retardation film of (1), wherein the wavelength dispersion of the support satisfies the following formula [5]:
[5] | Re (400) −Re (700) | ≦ 10 and 0 ≦ Rth (400) −Rth (700) ≦ 60.
(3) The retardation film according to (1) or (2), wherein the wavelength dispersion satisfies the following formula [6]:
[6] 1.06 ≦ Rth (450) / Rth (550) ≦ 1.30.
(4) A nematic liquid crystal phase state in which at least one layer of the optically anisotropic layer has a polymerizable liquid crystal composition containing at least one discotic liquid crystal compound and homeotropically aligns the molecules of the discotic liquid crystal compound. The retardation film according to any one of (1) to (3), which is a layer formed by being fixed by polymerization.
(5) At least one layer of the optically anisotropic layer is formed by fixing a polymerizable liquid crystal composition containing at least one rod-like liquid crystalline compound in a state of a cholesteric liquid crystal phase. The retardation film according to any one of (1) to (3), which is a layer.
(6) The retardation film according to any one of (1) to (3), wherein at least one of the optically anisotropic layers is a polymer layer.
(7) The retardation film according to (6), wherein the polymer layer contains at least one polymer selected from the group consisting of polyamide, polyimide, polyester, polyetherketone, polyamideimide, and polyesterimide.
(8) The retardation film according to any one of (1) to (7), wherein at least one of the optically anisotropic layers contains a fluorine-containing compound.
(9) The retardation film according to any one of (1) to (8), wherein the support comprises a cellulose acylate film containing a cellulose acylate having an acyl substitution degree of 2.70 to 3.00.
(10) The retardation film according to any one of (1) to (9), wherein the acrylic polymer has a weight average molecular weight of 500 or more and less than 10,000.
(11) The retardation film according to any one of (1) to (10), wherein the acrylic polymer is an acrylic polymer having a hydroxyl group in the main chain and / or side chain.
(12) The retardation film according to any one of (1) to (11), wherein the support is made of a cellulose acylate film containing a plasticizer.
(13) The retardation film according to any one of (1) to (12), wherein the support has a thickness of 10 to 60 μm.
(14) A polarizing plate having a polarizing film and protective films provided on both surfaces of the polarizing film, wherein at least one of the protective films is the retardation film of any one of (1) to (13).
(15) Furthermore, it has a second retardation film, the front retardation and the retardation in the thickness direction of the second retardation film satisfy the following formula [7], and the second retardation film The polarizing plate of (14) whose wavelength dispersion satisfies the following formula [8]:
[7] 70 ≦ Re (550) ≦ 180 and 30 ≦ Rth (550) ≦ 140
[8] 0.7 ≦ Re (450) / Re (550) ≦ 1.0.
(16) A liquid crystal display device comprising the retardation film of any one of (1) to (13) and / or the polarizing plate of (14) or (15).
(17) Two polarizing plates having mutually perpendicular absorption axes, and a pair of substrates between the two polarizing plates, and an external electric field is applied to the liquid crystal molecules sandwiched between the pair of substrates. A liquid crystal display device having a liquid crystal cell having a liquid crystal layer oriented in a direction substantially perpendicular to the pair of substrates in a non-driven state,
Furthermore, the liquid crystal display device which contains the phase difference film in any one of (1)-(13), or the said polarizing plate is a polarizing plate of (14) or (15).
(18) The liquid crystal display device further includes a second retardation film, the second retardation film is a polymer stretched film, and the front retardation and the retardation in the thickness direction are represented by the following formula [7 The liquid crystal display device according to (16) or (17):
[7] 70 ≦ Re (550) ≦ 180 and 30 ≦ Rth (550) ≦ 140.
(19) The liquid crystal display device further includes a second retardation film, and the wavelength dispersion of the second retardation film satisfies the following formula [8], and any one of (16) to (18) LCD device:
[8] 0.7 ≦ Re (450) / Re (550) ≦ 1.0.
(20) The liquid crystal display device further includes a second retardation film, and the second retardation film is a cellulose acylate film, a norbornene film, a polycarbonate film, a polyarylate film, or a polyester film. And the liquid crystal display device according to any one of (16) to (19), comprising any one of a polysulfone-based film.
(21) The liquid crystal display device further includes a second retardation film, and the second retardation film has an in-plane slow axis as an absorption axis of one of the two polarizing plates. The liquid crystal display device according to any one of (16) to (20), wherein the liquid crystal display device is disposed so as to be orthogonal to each other.

By using the retardation film and polarizing plate of the present invention, it is possible to optically compensate a liquid crystal cell (particularly a VA mode liquid crystal cell) with the same configuration as a conventional liquid crystal display device.
In particular, the retardation film and polarizing plate of the present invention contribute to alleviation of both oblique light leakage and color change in black display of liquid crystal display devices (particularly VA mode liquid crystal display devices), not only in the front direction. This contributes to improving the display characteristics in the oblique direction.
In addition, in the conventional liquid crystal display device, in order to accurately optically compensate the liquid crystal cell, a plurality of retardation films are strictly adjusted in the angle between the in-plane slow axis and the absorption axis of the polarizing plate. However, the process of laminating was necessary. However, in the retardation film of the present invention, it is not necessary to go through such a process. For example, the retardation film can be formed by continuously forming an optically anisotropic layer on a long support. Even when the polarizing plate is prepared, a long polarizing film can be continuously laminated. Furthermore, when an optically anisotropic layer is formed by coating, it is not necessary to increase the layer thickness to ensure optical characteristics, and problems such as unevenness during coating are unlikely to occur and can be stably produced. is there.
Furthermore, according to the present invention, the display characteristics when viewed from the front direction are good and the display characteristics when viewed from the oblique direction are also good. Specifically, the display characteristics are observed from the oblique direction during black display. Thus, it is possible to provide a liquid crystal display device, particularly a VA mode liquid crystal display device, in which light leakage and color change are reduced.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, the contents of the present invention will be described in detail. In the present specification, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

  In this specification, “substantially” for the angle means that the error from the exact angle is within a range of less than ± 5 °. Furthermore, the error from the exact angle is preferably less than 4 °, more preferably less than 3 °. Further, the measurement wavelength of the refractive index is a value at λ = 550 nm in the visible light region unless otherwise specified. In the present specification, “visible light” means light having a wavelength of 400 nm to 700 nm. Further, the measurement wavelength of the refractive index is a value at λ = 550 nm in the visible light region unless otherwise specified.

Re (λ) in the present invention is a front retardation value (unit: nm) at a wavelength λnm, and is represented by the following formula.
Re (λ) = (nx−ny) × d
(Where nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, nz is the refractive index in the thickness direction of the film, and d is (The thickness of the film (nm).)

Further, Rth (λ) in the present invention is a retardation value (unit: nm) in the film thickness direction at a wavelength λnm, and is represented by the following formula.
Rth = ((nx + ny) / 2−nz) × d
(Where nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, nz is the refractive index in the thickness direction of the film, and d is (The thickness of the film (nm).)

  In this specification, Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments). Rth (λ) is Re (λ), with the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotation axis) (if there is no slow axis, any in-plane film The light is incident at a wavelength of λ nm from the inclined direction in steps of 10 degrees from the normal direction to 50 degrees on one side with respect to the film normal direction of the rotation axis of KOBRA 21ADH or WR is calculated based on the measured retardation value, the assumed value of the average refractive index, and the input film thickness value. The retardation value is measured from any two directions with the slow axis as the tilt axis (rotation axis) (in the absence of the slow axis, the arbitrary direction in the film plane is the rotation axis), and the value Rth can also be calculated from the following formulas (1) and (2) based on the assumed average refractive index and the input film thickness value. Here, as the assumed value of the average refractive index, values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical films can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer. The average refractive index values of the main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). The KOBRA 21ADH or WR calculates nx, ny, and nz by inputting the assumed value of the average refractive index and the film thickness.

注記：上記のＲｅ（θ）は法線方向から角度θ傾斜した方向におけるレターデーション値を表す。 Formula (1)

Note: The above Re (θ) represents the retardation value in the direction inclined by the angle θ from the normal direction.

  In addition, the sign of Rth is when the retardation measured by injecting light having a wavelength of 550 nm from the direction inclined + 20 ° with respect to the film normal direction with the in-plane slow axis as the tilt axis (rotation axis) exceeds Re Is positive and negative is below Re. However, in the sample with | Rth / Re | of 9 or more, it was tilted by + 40 ° with respect to the film normal direction with the in-plane fast axis as the tilt axis (rotation axis) using a polarizing microscope with a free rotation base. In the state, the case where the slow axis of the sample which can be determined using the polarizing plate inspection plate is parallel to the film plane is positive, and the case where the slow axis is in the thickness direction of the film is negative.

  In addition, unless otherwise stated, “substituent” such as an alkyl group in the present specification may further have a substituent or may not have a substituent.

[Phase difference film]
The present invention relates to a retardation film obtained by combining a support made of a predetermined cellulose acylate film having a small absolute value of Re and Rth and an optically anisotropic layer. Specifically, the front retardation of the support and the retardation Rth in the thickness direction satisfy the following formula [1], and the wavelength dispersion of the support satisfies the following formula [2]. By combining with a layer, the retardation film as a whole relates to a retardation film in which the front retardation Re and the retardation Rth in the thickness direction satisfy the following formula [3] and the wavelength dispersion satisfies the following formula [4]. .
[1] 0 ≦ Re (630) ≦ 10 and | Rth (630) | ≦ 25
[2] | Re (400) −Re (700) | ≦ 10 and −35 ≦ Rth (400) −Rth (700) ≦ 60
[3] 0 ≦ Re (550) ≦ 10 and 100 ≦ Rth (550) ≦ 300
[4] 1.04 ≦ Rth (450) / Rth (550) ≦ 1.30

  The front retardation Re (550) of the retardation film of the present invention is preferably 8 nm or less, more preferably 5 nm or less, and further preferably 3 nm or less. The retardation Rth (550) in the thickness direction of the retardation film is preferably 120 to 280 nm, more preferably 140 to 260 nm, and still more preferably 160 to 240 nm. The wavelength dispersibility of the retardation film is preferably 1.06 to 1.30, more preferably 1.08 to 1.28, and even more preferably 1.10 to 1.26.

Hereinafter, preferable optical characteristics of the support and the optically anisotropic layer, and materials, methods, and the like used for manufacturing them will be described.
[Support]
A cellulose acylate film containing at least one acrylic polymer is used for the support of the retardation film of the present invention. Cellulose acylate films are generally preferred from the viewpoint that they do not absorb in the visible light region, have a light transmittance of 80% or more, and have a small retardation based on birefringence. Furthermore, the cellulose acylate film is preferable from the viewpoint that it can be directly bonded to the polarizing film and integrated with the polarizing plate, and also has an excellent function as a protective film for the polarizing film.

Specifically, the cellulose acylate film having a small optical anisotropy (Re, Rth) used as a support in the present invention has a front retardation Re and a retardation in the thickness direction of the cellulose acylate film (support). Rth satisfies the formula [1], and wavelength dispersion satisfies the formula [2].
Re and Rth of the support preferably satisfy the following formula [1] ′, and more preferably satisfy the following formula [1] ″.
[1] ′ 0 ≦ Re (630) ≦ 5 and | Rth (630) | ≦ 20 nm
[1] ”0 ≦ Re (630) ≦ 2 and | Rth (630) | ≦ 15 nm
The wavelength dispersion of the support preferably satisfies the following formula [2] ′, and more preferably satisfies the following formula [2] ″.
[2] ′ | Re (400) −Re (700) | ≦ 5 and −10 ≦ Rth (400) −Rth (700) ≦ 50
[2] "| Re (400) -Re (700) | ≤3 and 0≤Rth (400) -Rth (700) ≤45

[Cellulose acylate raw material cotton]
The cellulose acylate film can be formed from a composition containing cellulose acylate. Examples of cellulose used as a raw material for cellulose acylate include cotton linter and wood pulp (hardwood pulp, softwood pulp). Cellulose acylate obtained from any of the raw material celluloses can be used. Also good. Detailed descriptions of these raw material celluloses can be found in, for example, Plastic Materials Course (17) Fibrous Resin (Maruzawa, Uda, Nikkan Kogyo Shimbun, published in 1970) and Invention Association Open Technical Report 2001-1745 (page 7). To page 8), and any method can be preferably employed for the cellulose acylate film used in the present invention.

[Substitution degree of cellulose acylate]
The cellulose acylate used for the production of the cellulose acylate film is one in which the hydroxyl group of cellulose is acylated. For example, cellulose acylate substituted with an acetyl group having 2 to 22 carbon atoms of the acyl group is used. Is preferred. In the cellulose acylate used in the present invention, the degree of substitution of cellulose with a hydroxyl group is not particularly limited, but the degree of binding of acetic acid and / or a fatty acid having 3 to 22 carbon atoms substituted with a hydroxyl group of cellulose is measured and calculated. The degree of substitution can be obtained. As a measuring method, it can carry out according to ASTM D-817-91.

  Although the substitution degree to the hydroxyl group of a cellulose is not specifically limited, It is preferable that the acyl substitution degree to the hydroxyl group of a cellulose is 2.70-3.00. Furthermore, the substitution degree is preferably 2.80 to 3.00, and more preferably 2.85 to 3.00.

Among the acetic acid and / or the fatty acid having 3 to 22 carbon atoms substituted for the hydroxyl group of cellulose, the acyl group having 2 to 22 carbon atoms is not particularly limited, and may be an aliphatic group or an allyl group. It may be a mixture of more than one type. Examples of such an aliphatic group include an alkylcarbonyl ester group, an alkenylcarbonyl ester group, an aromatic carbonyl ester group, and an aromatic alkylcarbonyl ester group of cellulose. These groups may be further substituted with a substituent.
Specifically, examples of the acyl group include acetyl group, propionyl group, butanoyl group, heptanoyl group, hexanoyl group, octanoyl group, decanoyl group, dodecanoyl group, tridecanoyl group, tetradecanoyl group, hexadecanoyl group, octadecanoyl group, and octadecanoyl group. Noyl group, isobutanoyl group, tert-butanoyl group, cyclohexanecarbonyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group are preferred, acetyl group, propionyl group, butanoyl group, dodecanoyl group, octadecanoyl group, tert- A butanoyl group, an oleoyl group, a benzoyl group, a naphthylcarbonyl group, and a cinnamoyl group are more preferable, and an acetyl group, a propionyl group, and a butanoyl group are more preferable.

  In particular, among the acyl substituents substituted on the above-mentioned cellulose hydroxyl group, in the case of substantially consisting of at least two types of acetyl group / propionyl group / butanoyl group, the total degree of substitution is 2.70 to 3.00. In this case, the optical anisotropy of the cellulose acylate film can be more effectively reduced, and a cellulose acylate film satisfying the above formulas [1] and [2] can be stably produced. The acyl substitution degree is preferably 2.75 to 3.00, and more preferably 2.80 to 3.00.

[Acrylic polymer]
In the present invention, the cellulose acylate film used as a support contains at least one acrylic polymer. In the present specification, “acrylic polymer” means a homopolymer having acrylic acid and a derivative thereof (including not only acrylic ester but also acrylic acid having a substituent such as hydroxy group or acrylic ester) as a monomer, It is a generic term for copolymers, and homopolymers and copolymers having methacrylic acid and derivatives thereof (including not only methacrylic acid esters but also methacrylic acid and methacrylic acid esters having a substituent such as a hydroxy group) as monomers.
By adding the acrylic polymer to the cellulose acylate film, the optical anisotropy of the film is lowered. In the present invention, it is preferable to use an acrylic polymer having a weight average molecular weight of 500 or more and less than 10,000 (more preferably 500 to 5,000). When the weight average molecular weight is in the above range, the compatibility with the cellulose ester is good, and evaporation and volatilization hardly occur during film formation. In particular, the (meth) acrylic acid or (meth) acrylic acid ester polymer, the acrylic polymer having an aromatic ring in the side chain, or the acrylic polymer having a cyclohexyl group in the side chain, in addition to the above, The obtained cellulose acylate film has excellent transparency and extremely low moisture permeability, and therefore exhibits excellent performance as a protective film for polarizing plates.

  In addition, although expressed as an acrylic polymer, an acrylic polymer having a weight average molecular weight of 500 or more and less than 10,000 is considered to be between an oligomer and a low molecular weight polymer. In order to synthesize such a polymer, it is difficult to control the molecular weight in normal polymerization, and it is desirable to use a method that can align the molecular weight as much as possible by a method that does not increase the molecular weight so much. Such polymerization methods include a method using a peroxide polymerization initiator such as cumene peroxide and t-butyl hydroperoxide, a method using a polymerization initiator in a larger amount than normal polymerization, and a mercapto compound in addition to the polymerization initiator. And a method using a chain transfer agent such as carbon tetrachloride, a method using a polymerization terminator such as benzoquinone or dinitrobenzene in addition to the polymerization initiator, and further JP-A-2000-128911 or 2000-344823. Or a bulk polymerization method using a polymerization catalyst in which the compound and an organometallic compound are used in combination. Although preferably used, the method described in the publication is particularly preferable.

Although the monomer as a monomer unit which comprises the acrylic polymer useful for this invention is illustrated below, it is not limited to this.
Examples of monomer units constituting the polymer include: methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), butyl acrylate (n-, i-, s-, t-), pentyl acrylate (N-, i-, s-), hexyl acrylate (n-, i-), heptyl acrylate (n-, i-), octyl acrylate (n-, i-), nonyl acrylate (n- I-), myristyl acrylate (n-, i-), cyclohexyl acrylate, acrylic acid (2-ethylhexyl), benzyl acrylate, phenethyl acrylate, acrylic acid (ε-caprolactone), acrylic acid (2-hydroxy) Ethyl), acrylic acid (2-hydroxypropyl), acrylic acid (3-hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid 2-hydroxybutyl), acrylic acid (2-methoxyethyl), acrylic acid (2-ethoxyethyl), phenyl acrylate, acrylic acid (2 or 4-chlorophenyl), acrylic acid (2 or 3 or 4-ethoxycarbonylphenyl) ), Acrylic acid (o or m or p-tolyl), benzyl acrylate, phenethyl acrylate, acrylic acid (2-naphthyl), cyclohexyl acrylate, acrylic acid (4-methylcyclohexyl), acrylic acid (4-ethylcyclohexyl) ), Acrylic acid-p-hydroxymethylphenyl, acrylic acid-p- (2-hydroxyethyl) phenyl, etc .; a methacrylic acid ester in which the above acrylic acid ester is changed to a methacrylic acid ester; , Acrylic acid, methacrylic acid, maleic anhydride Examples thereof include acid, crotonic acid, itaconic acid and the like. The polymer composed of the above monomers may be a copolymer or a homopolymer.

It is preferable that the acrylic polymer has a hydroxyl group in the main chain and / or side chain, since the compatibility with cellulose acylate and the transparency of the resulting film are remarkably improved. An acrylic polymer having a hydroxyl group in the side chain can be produced by using a hydroxyl group-containing (meth) acrylic acid derivative (for example, a compound having a hydroxyl group in the ester portion of (meth) acrylic acid ester) as a monomer. . Specific examples of the (meth) acrylic acid derivative having a hydroxyl group include acrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), acrylic acid (3-hydroxypropyl), and acrylic acid (4-hydroxybutyl). Acrylic acid (2-hydroxybutyl), acrylic acid-p-hydroxymethylphenyl, acrylic acid-p- (2-hydroxyethyl) phenyl, etc .; those obtained by changing the above acrylic ester to methacrylic ester.
As the acrylic polymer having a hydroxyl group in the side chain, a copolymer of a compound having a hydroxyl group in the ester part of an acrylate ester and a methacrylic acid ester (a compound having no hydroxyl group in the ester part) is particularly preferable.

  Also, as described above, an acrylic polymer having a hydroxyl group in the main chain, particularly a hydroxyl group at at least one end of the main chain of the polymer is also preferable. To produce a polymer having a hydroxyl group at the end of the main chain, for example, a method using a radical polymerization initiator having a hydroxyl group such as azobis (2-hydroxyethylbutyrate); having a hydroxyl group such as 2-mercaptoethanol A method of using a chain transfer agent; a method of using a polymerization terminator having a hydroxyl group; a method of having a hydroxyl group at the terminal by living ion polymerization; as disclosed in JP 2000-128911 A or 2000-344823 A bulk polymerization using a compound having one thiol group and a secondary hydroxyl group, or a polymerization catalyst in which the compound and an organometallic compound are used in combination, and the like. preferable. The polymer produced by the method related to the description in this publication is commercially available as Act Flow Series manufactured by Soken Chemical Co., Ltd. and can be preferably used.

  In addition to the cellulose acylate film used as a support in the present invention, it is preferable to add a compound that lowers the optical anisotropy, and specifically, [0052] to [0052] of JP-A-2006-30937. [0134] A compound described in [0134] may be added.

[Wavelength dispersion adjusting agent]
Cellulose acylate films generally tend to have wavelength dispersion characteristics in which the values of Re and Rth are larger on the longer wavelength side than on the shorter wavelength side.
In the cellulose acylate film used as a support in the present invention, the value of | Re (400) −Re (700) | that can be an index of wavelength dispersion satisfies the above formula [2], preferably the above formula [ 2] ′, more preferably the above formula [2] ″.
In order to achieve the chromatic dispersion, an additive for adjusting chromatic dispersion may be added. As the wavelength dispersion adjusting agent, a compound having absorption in the ultraviolet region of 200 to 400 nm is usually used. For example, the wavelength dispersion of Re and / or Rth of the cellulose acylate film can be adjusted by adding the compound in an amount of 0.01 to 30% by mass based on the cellulose acylate solid content. The compound for adjusting the wavelength dispersion is sufficiently uniformly compatible with cellulose acylate, and the absorption band range in the ultraviolet region is preferably 200 to 400 nm, more preferably 220 to 395 nm, and further preferably 240 to 390 nm.

  In recent years, liquid crystal display devices such as televisions, notebook personal computers, and mobile portable terminals have been required to have excellent transmittance of optical members used in liquid crystal display devices in order to increase luminance with less power. In that respect, a compound having absorption in the ultraviolet region of 200 to 400 nm and reducing | Re (400) -Re (700) | and | Rth (400) -Rth (700) | When it is added, it is required to have excellent spectral transmittance. The cellulose acylate film preferably has a spectral transmittance of 45% to 95% at a wavelength of 380 nm and a spectral transmittance of 10% or less at a wavelength of 350 nm.

  As described above, the wavelength dispersion adjusting agent preferably used in the present invention preferably has a molecular weight of 250 to 1000 from the viewpoint of volatility. More preferably, it is 260-800, More preferably, it is 270-800, Most preferably, it is 300-800. The wavelength dispersion adjusting agent may be any of a monomer and an oligomer or a polymer in which the monomer is linked.

  The wavelength dispersion adjusting agent that can be used in the present invention is preferably not volatilized in the course of dope casting and drying when the cellulose acylate film is produced by a solvent cast method.

  Specific examples of the wavelength dispersion adjusting agent that can be used in the present invention include compounds described in JP-A-2006-30937, [0135] to [0211], and methods for using them.

[Plasticizer]
In order to improve the brittleness of the film, it is preferable to add a plasticizer to the cellulose acylate film that can be used as a support in the present invention. Specifically, it is possible to prevent the occurrence of cracks during film cutting. As the compound having a plasticizing effect, a compound having a functional group such as a phosphate ester, a carboxylic acid ester, an amide, an ether, and a urethane is preferable. Examples of these preferred compounds include, but are not limited to:
Phosphate esters include triphenyl phosphate, biphenyl diphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, trioctyl phosphate, tributyl phosphate, resorcinol bisdiphenyl phosphate, 1,3-phenylene bisdioxide. Examples include silenyl phosphate and bisphenol A bisdiphenyl phosphate.
Examples of carboxylic acid esters include trimethylolpropane tribenzoate, trimethylolpropane tricyclohexylcarboxylate, pentaerythritol tetrabutyrate, glycerin tributyrate, carboxylic acid esters of polyhydric alcohols such as triacetin, tributyrin, and tripropionine; dibutyl succinate; Diphenyl adipate, dibutyl phthalate, diaryl phthalate, dimethyl phthalate, diethyl phthalate, di-2-methoxyethyl phthalate, dioctyl phthalate, di-2-ethylhexyl phthalate, trimethyl trimellitic acid, pyromellitic acid And saturated and unsaturated polyvalent carboxylic acid esters such as tetraethyl; oligomers of methyl methacrylate and ethyl acrylate; and the like.
As esters of oxyacids, triethyl citrate, acetyl triethyl citrate, dibutyl tartrate, dibutyl diacetyl tartrate, butyl phthalyl butyl glycolate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, butyl phthalyl butyl glycol Mention may be made of esters of oxyacids such as glycolic acid such as rate, salicylic acid, citric acid, malic acid and tartaric acid.
Examples of the amide include carboxylic acid amides and sulfonic acid amides such as N-phenyl-benzenecarbonamide, N-phenyl-p-toluenesulfonamide, and N-ethyltoluenesulfonamide.
Other examples include sulfonic acid esters such as p-toluenesulfonic acid o-cresyl, and urethane by reaction of toluene diisocyanate with alcohols such as ethanol and hexyl alcohol.
Preferred examples include ether oligomers such as glycidyl ether of bisphenol A, and low molecular weight oligomers such as urethane oligomers obtained by reaction of toluene diisocyanate with a dihydric alcohol and a monohydric alcohol mixture.
Other preferred examples include trityl alcohol.
The amount of the compound exhibiting a plastic effect is preferably 5 to 30 parts by mass, and more preferably 10 to 25 parts by mass with respect to 100 parts by mass of cellulose acylate.

  In addition to the cellulose acylate film, matting agent fine particles, deterioration preventing agents, release agents, and the like may be added as additives conventionally used in cellulose acylate films. Specifically, compounds described in [0212] to [0219] of JP-A-2006-30937 and methods for using them are used.

  The cellulose acylate film used as a support in the present invention is preferably produced by a solvent cast method, specifically, produced by the method described in JP-A-2006-30937, [0220] to [0225]. It is preferable to do this.

[Optically anisotropic layer]
The retardation film of the present invention has at least one optically anisotropic layer on the support. As long as the retardation film of the present invention satisfying the above optical characteristics is obtained by laminating with the support having the predetermined optical characteristics, the material and form thereof are basically not particularly limited. For example, it may be a polymer film (preferably a retardation film made of a birefringent polymer film), or a film obtained by heating and stretching after forming a layer containing a polymer compound on a support. Alternatively, it may be a layer formed after the liquid crystalline composition is made into a predetermined liquid crystal phase and then fixed in that state. Moreover, you may laminate | stack each.

[Optically anisotropic layer formed from polymerizable liquid crystal composition]
The optically anisotropic layer is preferably a layer formed by forming a polymerizable liquid crystalline composition into a predetermined liquid crystal phase and then fixing the alignment state by polymerization.
As one aspect thereof, a polymerizable liquid crystal composition containing at least one discotic liquid crystal compound is formed by homeotropic alignment of the molecules of the discotic liquid crystal compound and fixed by polymerization in a nematic liquid crystal phase. Layer. Another embodiment includes a layer formed by fixing a polymerizable liquid crystal composition containing at least one rod-like liquid crystalline compound in a state of a cholesteric liquid crystal phase.

[Disc liquid crystalline compound]
As the discotic liquid crystalline compound that can be used for forming the optically anisotropic layer,

Various references (C. Destrade et al., Mol. Crysr. Liq. Cryst., Vol. 71, page 111 (1981); edited by the Chemical Society of Japan, Quarterly Chemical Review, No. 22, Liquid Crystal Chemistry, Chapter 5) , Chapter 0, Section 2 (1994); B. Kohne et al., Angew. Chem. Soc. Chem. Comm., Page 1794 (1985), J. Zhang et al., J. Am. , Vol.116, page 2655 (1994)) can be used.
For the polymerization of the discotic liquid crystalline compound, for example, a method described in JP-A-8-27284 can be employed.

The discotic liquid crystalline compound preferably has a polymerizable group so that it can be fixed by polymerization. For example, a structure in which a polymerizable group is bonded as a substituent to a discotic core of a discotic liquid crystalline compound can be considered. A structure having a linking group between the discotic core and the polymerizable group is more preferable. When a structure having a linking group is employed, it becomes easier to maintain the alignment state in the polymerization reaction. The discotic liquid crystalline compound having a polymerizable group is preferably a compound represented by the following general formula (VI).
Formula (VI)
D (-LP) _n
(In general formula (VI), D is a discotic core, L is a divalent linking group, P is a polymerizable group, and n is an integer of 4 to 12.)

  The discotic core (D), divalent linking group (L) and polymerizable group (P) in the formula (VI) are, for example, (D1) to (D15) described in JP-A-2001-4837. , (L1) to (L25) and (P1) to (P18) can be used. Specific examples include TE-8 shown below.

  The discotic liquid crystalline compound can be aligned substantially horizontally with respect to the cellulose acylate film surface as a support by using at least one of the fluorine-containing compounds described later. Here, “substantially horizontal” means that the average angle (average inclination angle) between the disc surface of the discotic liquid crystalline compound and the surface of the optically anisotropic layer is in the range of 0 ° to 10 °. . Moreover, also when using the discotic liquid crystalline compound which has a polymeric group, the molecule | numerator of a discotic liquid crystalline compound is substantially horizontally aligned like the above. As specific examples of the discotic liquid crystalline compound in this case, those described in International Publication WO01 / 88574A1 pamphlet, page 58, line 6 to page 65, line 8 can be preferably employed.

[Fluorine-containing compounds]
At the time of forming the optically anisotropic layer, at least one kind of fluorine-containing compound is formed in order to align liquid crystalline compounds (particularly discotic liquid crystalline compounds) or to make optical characteristics uniform in the plane. It is preferable to be contained in the composition for use. The fluorine-containing compound is preferably a fluorine-containing surfactant. The fluorine-containing compound may be a low molecular compound or a high molecular compound. For example, for low molecular compounds, compounds exemplified in JP-A-2005-128050 are preferred.

  As the polymer fluorine-containing compound, a fluoroaliphatic-containing polymer containing a repeating unit represented by the following general formula (1) is preferable.

General formula (1)

In the general formula (1), R ¹ , R ² and R ³ are each independently a hydrogen atom, an alkyl group, a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.) A group represented by LQ, preferably a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a chlorine atom, or a group represented by -LQ, and more preferably a hydrogen atom or a group having 1 to 1 carbon atoms. 4 is an alkyl group, particularly preferably a hydrogen atom or an alkyl group having 1 to 2 carbon atoms. Specific examples of the alkyl group include methyl group, ethyl group, n-propyl group, n-butyl group, sec-butyl group and the like. The alkyl group may have a suitable substituent. Examples of the substituent include a halogen atom, aryl group, heterocyclic group, alkoxyl group, aryloxy group, alkylthio group, arylthio group, acyl group, hydroxyl group, acyloxy group, amino group, alkoxycarbonyl group, acylamino group, oxycarbonyl Group, carbamoyl group, sulfonyl group, sulfamoyl group, sulfonamido group, sulfolyl group, carboxyl group and the like.
The carbon number of the alkyl group does not include the carbon atom of the substituent. The same applies to the carbon number of other groups.

L is a single bond, —O—, —CO—, —NR ⁴ —, —S—, —SO ₂ —, —PO (OR ⁵ ) —, an alkylene group, an arylene group, or a combination thereof. Represents a valent linking group. Here, R ⁴ represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group. R ⁵ represents an alkyl group, an aryl group, or an aralkyl group.
L preferably includes a single bond, —O—, —CO—, —NR ⁴ —, —S—, —SO ₂ —, an alkylene group, or an arylene group, and includes —CO—, —O—, — It is particularly preferred that it contains NR ⁴ —, an alkylene group, or an arylene group.
When L contains an alkylene group, the alkylene group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and particularly preferably 1 to 6 carbon atoms. Specific examples of particularly preferred alkylene groups include methylene, ethylene, trimethylene, tetrabutylene, hexamethylene groups and the like.
When L contains an arylene group, the carbon number of the arylene group is preferably 6 to 24, more preferably 6 to 18, and particularly preferably 6 to 12. Specific examples of particularly preferred arylene groups include phenylene and naphthalene groups.
When L contains a divalent linking group (that is, an aralkylene group) obtained by combining an alkylene group and an arylene group, the carbon number of the aralkylene group is preferably 7 to 34, more preferably 7 to 26, and particularly preferably. 7-16. Specific examples of particularly preferred aralkylene groups include a phenylenemethylene group, a phenyleneethylene group, and a methylenephenylene group.
The group listed as L may have a suitable substituent. Examples of such a substituent include those similar to the substituents exemplified above as the substituents for R ^{1 to} R ³ .
Although the specific structure of L is illustrated below, this invention is not limited to these specific examples.

Q is not particularly limited as long as it is a polar group having hydrogen bonding properties. Preferably, hydroxyl group, carboxyl group, salt of carboxyl group (for example, lithium salt, sodium salt, potassium salt, ammonium salt (for example, ammonium, tetramethylammonium, trimethyl-2-hydroxyethylammonium, tetrabutylammonium, trimethylbenzylammonium, dimethylphenyl) ammonium etc.), pyridinium salt), an amide group of the carboxylic acid (N unsubstituted bodies, N- mono-lower alkyl-substituted, or N- di-lower alkyl-substituted bodies, e.g. _{-CONH 2, -CONHCH 3, -CON (} CH 3 ₂ ), a sulfo group, a salt of a sulfo group (examples of cations forming the salt are the same as those described for the carboxyl group), a sulfonamide group (N unsubstituted, N-mono lower alkyl substituted or N-di-lower alkyl substituents such as -S _{2 NH 2, -SO 2 NHCH 3} , such as _{-SO 2 N (CH 3) 2} ), phospho group, examples of the cation forming the salt of phospho group (salt are the same as those described in the above carboxyl group), a phosphonic amide (N unsubstituted, or N- mono-lower alkyl substituted compound, for example, _{-OP (= O) (NH 2} ) 2, -OP (= O) (NHCH 3) 2 , etc.), a ureido group (-NHCONH _2), Examples thereof include an amino group (—NH ₂ , —NHCH ₃ ) which is unsubstituted or monosubstituted at the N position (wherein the lower alkyl group represents a methyl group or an ethyl group). More preferred are a hydroxyl group, a carboxyl group, a sulfo group, and a phospho group, and particularly preferred is a hydroxyl group or a carboxyl group.

  The repeating unit contained in the polymer may be one kind alone, or two or more kinds of repeating units may be present simultaneously. A repeating unit having a carboxylic acid or a repeating unit having an acrylamide group is particularly preferred.

  Further, the fluoroaliphatic-containing polymer may have one or more repeating units derived from a fluoroaliphatic group-containing monomer. Preferably, it contains a fluoroaliphatic group-containing monomer described in general formula (I) or general formula (II) in JP-A-2006-126768. Specifically, it may contain one type of repeating unit derived from a monomer selected from the monomer group described in JP-A 2006-126768 [0033] to [0044], or two or more types. You may do it.

  Further, the fluoroaliphatic-containing polymer may contain a repeating unit other than the above. The other repeating units are not particularly limited, and preferred examples thereof include repeating units derived from ordinary radical polymerizable monomers. The fluoroaliphatic polymer may contain one type of repeating unit derived from a monomer selected from the monomer group described in [0026] to [0033] of JP-A-2004-46038, You may contain more than a seed.

  The fluoroaliphatic-containing polymer may contain a repeating unit derived from a monomer represented by the general formula [2] described in JP-A-2004-333852.

  The fluoroaliphatic-containing polymer may have a polymerizable group as a substituent in order to fix the alignment state of the liquid crystal compound.

  In the fluoroaliphatic-containing polymer used in the present invention, the polymerized units of the monomer having a fluoroaliphatic group is preferably 25 to 99% by mass based on the total polymerized units constituting the fluoropolymer. A more desirable ratio varies depending on the structure of the fluoroaliphatic group, and the polymerized units of the monomer represented by the general formula (I) in JP-A-2006-126768 are based on the total polymerized units constituting the fluoropolymer, It is preferably 99% by mass, more preferably 60-97% by mass, and even more preferably 70-95% by mass. The polymerization unit of the monomer represented by the general formula (II) in JP-A-2006-126768 is preferably 25 to 80% by mass based on the total polymerization units constituting the fluoropolymer, and 30 to 70% by mass. % Is more preferable, and it is more preferable that it is 35-65 mass%. Further, two or more kinds of fluoroaliphatic group-containing monomers may be contained in one polymer, and each of the monomers represented by the general formula (I) and the monomer represented by the general formula (II) is one or more types. It may be included at the same time.

  A preferred mass average molecular weight of the fluoroaliphatic-containing polymer used in the present invention is 2000 to 100,000, more preferably 3000 to 80,000, and further preferably 4,000 to 60,000. Here, the mass average molecular weight and the molecular weight were converted to polystyrene by GTH analyzer using a column of TSKgel GMHxL, TSKgel G4000HxL, TSKgel G2000HxL (both trade names manufactured by Tosoh Corp.), and detection by solvent THF and differential refractometer. Is the molecular weight.

  The said fluoroaliphatic content polymer used for this invention can be manufactured by a well-known and usual method. For example, it can be produced by adding a general-purpose radical polymerization initiator into an organic solvent containing a fluorine-based monomer, a monomer having a hydrogen bonding group, and the like, and polymerizing it. Further, in some cases, other addition-polymerizable unsaturated compounds can be further added and produced by the same method as described above. Depending on the polymerizability of each monomer, a dropping polymerization method in which a monomer and an initiator are added dropwise to a reaction vessel is also effective for obtaining a polymer having a uniform composition. More specifically, it is preferable to use the method described in [0035] to [0041] of JP-A-2004-46038.

[Bar-shaped liquid crystalline compound]
Further, as described above, the optically anisotropic layer is formed by fixing a polymerizable liquid crystal composition containing at least one rod-like liquid crystalline compound in a state of a cholesteric liquid crystal phase. A layer is also preferred. Examples of the rod-like liquid crystal compound include liquid crystal monomer molecules (polymerizable liquid crystal molecules) used in a twist-aligned polymerizable chiral nematic (cholesteric) liquid crystal layer having a reflection wavelength capable of three-dimensional crosslinking in the ultraviolet region. Examples of the polymerizable liquid crystal composition include a mixture of a liquid crystal monomer and a chiral compound as disclosed in JP-A-7-258638 and JP-T-10-508882. Specific examples of the polymerizable rod-like liquid crystal compound that can be used in the polymerizable liquid crystal composition include the following compounds A to K. These compounds may be mixed. For example, two or more types selected from the following compounds A to J, or a mixture of two or more compounds included in the range of the following compound K can be used. . In the following compound K, X represents an integer, but X is preferably an integer of 2 to 5.

  Specific examples of the chiral agent include chiral agents represented by the following compounds L to N. In compound L or compound M, X represents an integer, but X is preferably an integer of 2 to 12. In compound N, X represents an integer, but X is It is desirable that it is an integer of 2-5.

Compound A

Compound B

Compound C

Compound D

Compound E

Compound F

Compound G

Compound H

Compound I

Compound J

Compound K

Compound L

Compound M

Compound N

[Fixation of alignment state of liquid crystalline compounds]
When the optically anisotropic layer is formed from a liquid crystal composition containing a liquid crystal compound, it is preferable to fix the aligned liquid crystal compound molecules while maintaining the alignment state. The immobilization is preferably performed by a polymerization reaction of a polymerizable group introduced into the molecule of the liquid crystal compound. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator, and a photopolymerization reaction is more preferable. Examples of the photopolymerization initiator include α-carbonyl compounds (described in the specifications of U.S. Pat. Nos. 2,367,661 and 2,367,670), acyloin ethers (as described in U.S. Pat. No. 2,448,828). , Α-hydrocarbon-substituted aromatic acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (described in US Pat. Nos. 3,046,127 and 2,951,758), triarylimidazoles Combination of dimer and p-aminophenyl ketone (described in US Pat. No. 3,549,367), acridine compound and phenazine compound (described in JP-A-60-105667, US Pat. No. 4,239,850) ) And oxadiazole compounds (U.S. Pat. No. 4,221,970) As described in the booklet).

The amount of the photopolymerization initiator used is preferably 0.01 to 20% by mass, and 0.5 to 5% by mass of the composition for forming an optically anisotropic layer (in the case of a coating liquid, its solid content). More preferably. Light irradiation for the polymerization of the liquid crystalline compound is preferably performed using ultraviolet rays. The irradiation energy is preferably ^{20mJ / cm 2 ~50J / cm 2} , further preferably 100 to 800 mJ / cm ^2. In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.
The thickness of the optically anisotropic layer is preferably 0.1 to 10 μm, and more preferably 0.5 to 5 μm.

  The optically anisotropic layer is prepared by preparing a polymerizable liquid crystal composition containing a liquid crystal compound and, if necessary, the above-described polymerization initiator and other additives as a coating liquid, and then applying the coating liquid to a support (optionally). It is preferably formed by applying to the surface of the (alignment film), drying and polymerizing. As the solvent used for the preparation of the optically anisotropic layer coating solution, an organic solvent is preferably used. Examples of the organic solvent include amide (for example, N, N-dimethylformamide), sulfoxide (for example, dimethyl sulfoxide), heterocyclic compound (for example, pyridine), hydrocarbon (for example, benzene, hexane), alkyl halide (for example, , Chloroform, dichloromethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane) can be employed. Of these, alkyl halides and ketones are preferred. Further, two or more organic solvents may be used in combination. For the application of the coating solution, known methods (for example, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method) can be widely adopted.

[Alignment film]
In forming the optically anisotropic layer, it is preferable to use an alignment film in order to align the molecules of the liquid crystalline compound. Furthermore, an alignment film in which an alignment function is generated by application of an electric field, application of a magnetic field or light irradiation is also known. The kind of polymer used for the alignment film can be determined according to the alignment mode (for example, average inclination angle) of the molecules of the liquid crystal compound. For example, in order to align the liquid crystalline compound horizontally, a polymer (ordinary alignment polymer) that does not decrease the surface energy of the alignment film is used. Regarding specific types of polymers, matters described in known literatures on liquid crystal cells or optical compensation sheets can be widely adopted. In particular, when the molecules of the liquid crystal compound are aligned in a direction orthogonal to the rubbing treatment direction, for example, modified polyvinyl alcohol described in JP-A No. 2002-62427, described in JP-A No. 2002-98836 Acrylic acid-based copolymers, polyimides described in JP-A No. 2002-268068, and polyamic acid can be preferably used. In any alignment film, in order to improve the adhesion between the optically anisotropic layer and the alignment film (resulting in the optically anisotropic layer and the support), a polymer having a polymerizable group in the alignment film It is preferable to contain. The polymerizable group can be introduced by introducing a repeating unit having a polymerizable group in the side chain or as a substituent of a cyclic group. It is more preferable to use an alignment film that forms a chemical bond with the liquid crystal compound at the interface. As such an alignment film, for example, those described in JP-A-9-152509 can be employed.

  The thickness of the alignment film is preferably 0.01 to 5 μm, and more preferably 0.05 to 2 μm. In addition, after aligning the molecules of the liquid crystalline compound using the alignment film, the liquid crystalline compound is fixed in the aligned state to form an optically anisotropic layer, and only the optically anisotropic layer is formed on the support. You may transfer to.

[Optically anisotropic layer composed of polymer layer]
The optically anisotropic layer may be a polymer layer made of a stretched or unstretched polymer film, or a polymer layer formed by applying a polymer composition to the support surface. Furthermore, after a polymer layer is formed on the support, stretching may be performed as a whole to develop optical characteristics that satisfy the conditions required for the support and retardation film. Although there is no restriction | limiting in particular about the polymer material used for formation of the said polymer layer, The various polymer material from which the refractive index of the in-plane direction with respect to the normal line direction of a film surface becomes large after film-forming is preferable. In such a case, the polymerization proceeds in the process of forming the polymer layer. In such a case, it is preferable to use a polymerizable low molecular weight compound that can give the polymer. Specifically, materials disclosed in JP 2000-190385 A and JP 2004-226945 A can be used. For example, giving various polymers such as polyamide, polyimide, polyamic acid, polyester, polyetherketone, polyaryletherketone, polyamideimide, polyesterimide or polyesteramide having at least one kind of aromatic ring, or these polymers And a polymerizable low molecular weight compound. These may be used alone or in combination.

  Moreover, the film which extended | stretched the film after film-forming the said polymer film etc., and added the process which enlarges in-plane optical anisotropy can also be employ | adopted. 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. From the viewpoint of effectively expressing Rth, the biaxial stretching method is preferable.

  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, it includes a condensation polymerization product of 9,9-bis (aminoaryl) fluorene and an aromatic tetracarboxylic dianhydride disclosed in JP 2000-511296 A, and has the following formula ( A polymer containing one or more repeating units shown in 1) can be used.

In the formula (1), R ^{3 to} R ⁶ are a group consisting of hydrogen, halogen, a phenyl group, a phenyl group substituted with 1 to 4 halogen atoms or a C1-10 alkyl group, and a C1-10 alkyl group. Are at least one kind of substituents independently selected from the above. Preferably, R ^{3 to} R ⁶ are each independently selected from the group consisting of halogen, a phenyl group, a phenyl group substituted with 1 to 4 halogen atoms or a C 1-10 alkyl group, and a C 1-10 alkyl group. At least one kind of substituent.

  In the formula (1), Z is, for example, a C6-20 tetravalent aromatic group, preferably a pyromellitic group, a polycyclic aromatic group, a derivative of a polycyclic aromatic group, or the following It is group represented by Formula (2).

In the formula (2), Z ′ is, for example, a covalent bond, C (R ⁷ ) ₂ group, CO group, O atom, S atom, SO ₂ group, Si (C ₂ H ₅ ) ₂ group, or NR ^{There are 8} groups, and when there are a plurality of groups, they are the same or different. W represents an integer of 1 to 10. R ⁷ is independently hydrogen or C (R ⁹ ) ₃ . R ⁸ is hydrogen, an alkyl group having 1 to about 20 carbon atoms, or a C 6-20 aryl group, and in a plurality of cases, they are the same or different. Each R ⁹ is independently hydrogen, fluorine, or chlorine.

  Examples of the polycyclic aromatic group include a tetravalent group derived from naphthalene, fluorene, benzofluorene or anthracene. Examples of the substituted derivative of the polycyclic aromatic group include a C1-10 alkyl group, a fluorinated derivative thereof, and at least one group selected from the group consisting of halogens such as F and Cl. In addition, the polycyclic aromatic group is exemplified.

  In addition to this, for example, a homopolymer described in JP-A-8-511812, wherein the repeating unit is represented by the following general formula (3) or (4), or the repeating unit is represented by the following general formula (5). The polyimide etc. which are shown are mention | raise | lifted. In addition, the polyimide of following formula (5) is a preferable form of the homopolymer of following formula (3).

In the general formulas (3) to (5), G and G ′ are, for example, a covalent bond, a CH ₂ group, a C (CH ₃ ) ₂ group, a C (CF ₃ ) ₂ group, or a C (CX ₃ ) ₂ group. (Where X is a halogen), respectively, from the group consisting of CO, O, S, SO ₂ , Si (CH ₂ CH ₃ ) ₂ and N (CH ₃ ) groups It represents independently selected groups, and may be the same or different.

  In said Formula (3) and Formula (5), L is a substituent and d and e represent the substitution number. L is, for example, a halogen, a C1-3 alkyl group, a C1-3 halogenated alkyl group, a phenyl group, or a substituted phenyl group, and in a plurality of cases, they are the same or different. Examples of the substituted phenyl group include substituted phenyl groups having at least one type of substituent selected from the group consisting of halogen, C1-3 alkyl groups, and C1-3 halogenated alkyl groups. Examples of the halogen include fluorine, chlorine, bromine and iodine. d is an integer of 0 to 2, and e is an integer of 0 to 3.

  In the formulas (3) to (5), Q is a substituent, and f represents the number of substitutions. Q is, for example, selected from the group consisting of hydrogen, halogen, alkyl group, substituted alkyl group, nitro group, cyano group, thioalkyl group, alkoxy group, aryl group, substituted aryl group, alkyl ester group, and substituted alkyl ester group And when Q is plural, they are the same or different. Examples of the halogen include fluorine, chlorine, bromine and iodine. Examples of the substituted alkyl group include a halogenated alkyl group. Examples of the substituted aryl group include a halogenated aryl group. f is an integer of 0 to 4, and g and h are integers of 0 to 3 and 1 to 3, respectively. Further, g and h are preferably larger than 1.

In the formula (4), R ¹⁰ and R ¹¹ are groups independently selected from the group consisting of hydrogen, halogen, phenyl group, substituted phenyl group, alkyl group, and substituted alkyl group. Among these, R ¹⁰ and R ¹¹ are preferably each independently a halogenated alkyl group.

In the above formula (5), M ¹ and M ² are the same or different and are, for example, halogen, C1-3 alkyl group, C1-3 halogenated alkyl group, phenyl group, or substituted phenyl group. Examples of the halogen include fluorine, chlorine, bromine and iodine. Examples of the substituted phenyl group include substituted phenyl groups having at least one type of substituent selected from the group consisting of halogen, C1-3 alkyl groups, and C1-3 halogenated alkyl groups.

  Specific examples of the polyimide represented by the formula (3) include those represented by the following formula (6).

  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 pyromellitic dianhydride include pyromellitic dianhydride, 3,6-diphenylpyromellitic dianhydride, 3,6-bis (trifluoromethyl) pyromellitic dianhydride, and 3,6-dibromo. Examples include pyromellitic dianhydride and 3,6-dichloropyromellitic dianhydride. Examples of the benzophenone tetracarboxylic dianhydride include 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 2,3,3 ′, 4′-benzophenone tetracarboxylic dianhydride, 2 , 2 ′, 3,3′-benzophenonetetracarboxylic dianhydride and the like. Examples of the naphthalenetetracarboxylic dianhydride include 2,3,6,7-naphthalene-tetracarboxylic dianhydride, 1,2,5,6-naphthalene-tetracarboxylic dianhydride, 2,6 -Dichloro-naphthalene-1,4,5,8-tetracarboxylic dianhydride and the like. Examples of the heterocyclic aromatic tetracarboxylic dianhydride include thiophene-2,3,4,5-tetracarboxylic dianhydride and pyrazine-2,3,5,6-tetracarboxylic dianhydride. Pyridine-2,3,5,6-tetracarboxylic dianhydride and the like. Examples of the 2,2′-substituted biphenyltetracarboxylic dianhydride include 2,2′-dibromo-4,4 ′, 5,5′-biphenyltetracarboxylic dianhydride and 2,2′-dichloro. -4,4 ', 5,5'-biphenyltetracarboxylic dianhydride, 2,2'-bis (trifluoromethyl) -4,4', 5,5'-biphenyltetracarboxylic dianhydride, etc. can give.

  Other examples of the aromatic tetracarboxylic dianhydride include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and bis (2,3-dicarboxyphenyl) methane dianhydride. Bis (2,5,6-trifluoro-3,4-dicarboxyphenyl) methane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3 3-hexafluoropropane dianhydride, 4,4′-bis (3,4-dicarboxyphenyl) -2,2-diphenylpropane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, 4,4′-oxydiphthalic dianhydride, bis (3,4-dicarboxyphenyl) sulfonic dianhydride, 3,3 ′, 4,4′-diphenylsulfone tetracarboxylic dianhydride, 4,4 ′ − [4,4′− Sopropylidene-di (p-phenyleneoxy)] bis (phthalic anhydride), N, N- (3,4-dicarboxyphenyl) -N-methylamine dianhydride, bis (3,4-dicarboxyphenyl) And diethylsilane dianhydride.

  Among these, the aromatic tetracarboxylic dianhydride is preferably 2,2′-substituted biphenyltetracarboxylic dianhydride, more preferably 2,2′-bis (trihalomethyl) -4,4. ', 5,5'-biphenyltetracarboxylic dianhydride, more preferably 2,2'-bis (trifluoromethyl) -4,4', 5,5'-biphenyltetracarboxylic dianhydride It is.

  Examples of the diamine include aromatic diamines, and specific examples include benzene diamine, diaminobenzophenone, naphthalene diamine, heterocyclic aromatic diamine, and other aromatic diamines.

  Examples of the benzenediamine include o-, m-, and p-phenylenediamine, 2,4-diaminotoluene, 1,4-diamino-2-methoxybenzene, 1,4-diamino-2-phenylbenzene, and 1, Examples include diamines selected from the group consisting of benzenediamines such as 3-diamino-4-chlorobenzene. Examples of the diaminobenzophenone include 2,2'-diaminobenzophenone and 3,3'-diaminobenzophenone. Examples of the naphthalenediamine include 1,8-diaminonaphthalene and 1,5-diaminonaphthalene. Examples of the heterocyclic aromatic diamine include 2,6-diaminopyridine, 2,4-diaminopyridine, and 2,4-diamino-S-triazine.

  In addition to these, the aromatic diamine includes 4,4′-diaminobiphenyl, 4,4′-diaminodiphenylmethane, 4,4 ′-(9-fluorenylidene) -dianiline, 2,2′-bis ( Trifluoromethyl) -4,4′-diaminobiphenyl, 3,3′-dichloro-4,4′-diaminodiphenylmethane, 2,2′-dichloro-4,4′-diaminobiphenyl, 2,2 ′, 5 5′-tetrachlorobenzidine, 2,2-bis (4-aminophenoxyphenyl) propane, 2,2-bis (4-aminophenyl) propane, 2,2-bis (4-aminophenyl) -1,1, 1,3,3,3-hexafluoropropane, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 1,3-bis (3-aminophen Xyl) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 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, and the like.

  As said polyetherketone, the polyaryletherketone represented by following General formula (7) described in Unexamined-Japanese-Patent No. 2001-49110 is mention | raise | lifted, for example.

  In the formula (7), X represents a substituent, and q represents the number of substitutions. X is, for example, a halogen atom, a lower alkyl group, a halogenated alkyl group, a lower alkoxy group, or a halogenated alkoxy group, and when there are a plurality of X, they are the same or different.

  Examples of the halogen atom include a fluorine atom, a bromine atom, a chlorine atom, and an iodine atom, and among these, a fluorine atom is preferable. The lower alkyl group is, for example, preferably a C1-6 linear or branched lower alkyl group, more preferably a C1-4 linear or branched alkyl group. Specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group are preferable, and a methyl group and an ethyl group are particularly preferable. Examples of the halogenated alkyl group include halides of the lower alkyl group such as a trifluoromethyl group. As the lower alkoxy group, for example, a C1-6 linear or branched alkoxy group is preferable, and a C1-4 linear or branched alkoxy group is more preferable. Specifically, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a sec-butoxy group, and a tert-butoxy group are more preferable, and a methoxy group and an ethoxy group are particularly preferable. . Examples of the halogenated alkoxy group include halides of the lower alkoxy group such as a trifluoromethoxy group.

In said Formula (7), q is an integer of 0-4. In the above formula (7), it is preferable that q = 0 and that the carbonyl group bonded to both ends of the benzene ring and the oxygen atom of the ether are present in the para position. In the formula (7), R ¹ is a group represented by the following formula (8), and m is an integer of 0 or 1.

  In the formula (8), X ′ represents a substituent, and is the same as X in the formula (7), for example. In Formula (8), when there are a plurality of X ′, they are the same or different. q ′ represents the number of substitutions of X ′ and is an integer of 0 to 4, preferably q ′ = 0. P is an integer of 0 or 1.

In the formula (8), R ² represents a divalent aromatic group. Examples of the divalent aromatic group include an o-, m- or p-phenylene group, or naphthalene, biphenyl, anthracene, o-, m- or p-terphenyl, phenanthrene, dibenzofuran, biphenyl ether, or And divalent groups derived from biphenylsulfone. In these divalent aromatic groups, hydrogen directly bonded to the aromatic group may be substituted with a halogen atom, a lower alkyl group or a lower alkoxy group. Among these, R ² is preferably an aromatic group selected from the group consisting of the following formulas (9) to (15).

In the formula (7), R ¹ is preferably a group represented by the following formula (16). In the following formula (16), R ² and p have the same meanings as the formula (8).

  Furthermore, in said Formula (7), n represents a polymerization degree, for example, is the range of 2-5000, Preferably, it is the range of 5-500. Further, the polymerization may be composed of repeating units having the same structure, or may be composed of repeating units having different structures. In the latter case, the polymerization mode of the repeating unit may be block polymerization or random polymerization.

  Furthermore, the end of the polyaryl ether ketone represented by the formula (7) is preferably fluorine on the p-tetrafluorobenzoylene group side and a hydrogen atom on the oxyalkylene group side. For example, it can be represented by the following general formula (17). In the following formula, n represents the same degree of polymerization as in formula (7).

  Specific examples of the polyaryletherketone represented by the formula (7) include those represented by the following formulas (18) to (21). In each formula below, n represents the formula (7). Represents the same degree of polymerization.

  In addition to these, examples of the polyamide or polyester include polyamides and polyesters described in JP-T-10-508048, and their repeating units are represented by the following general formula (22), for example. Can be represented.

In the formula (22), Y is O or NH. E is, for example, a covalent bond, a C2 alkylene group, a halogenated C2 alkylene group, a CH ₂ group, a C (CX ₃ ) ₂ group (where X is a halogen or hydrogen), a CO group, and an O atom. , S atom, SO ₂ group, Si (R) ₂ group, and N (R) group, which may be the same or different from each other. In E, R is at least one of a C1-3 alkyl group and a C1-3 halogenated alkyl group, and is in a meta position or a para position with respect to a carbonyl functional group or a Y group.

  Moreover, in said (22), A and A 'are substituents, and t and z represent the number of each substitution. Moreover, p is an integer of 0-3, q is an integer of 1-3, r is an integer of 0-3.

  The A is, for example, hydrogen, halogen, C1-3 alkyl group, C1-3 halogenated alkyl group, an alkoxy group represented by OR (where R is as defined above), an aryl group, Substituted aryl groups by halogenation, etc., C1-9 alkoxycarbonyl groups, C1-9 alkylcarbonyloxy groups, C1-12 aryloxycarbonyl groups, C1-12 arylcarbonyloxy groups and substituted derivatives thereof, C1-12 arylcarbamoyl groups, And selected from the group consisting of a C1-12 arylcarbonylamino group and a substituted derivative thereof, and in a plurality of cases, they are the same or different. The A ′ is selected from the group consisting of halogen, C1-3 alkyl group, C1-3 halogenated alkyl group, phenyl group and substituted phenyl group, and in a plurality of cases, they are the same or different. Examples of the substituent on the phenyl ring of the substituted phenyl group include halogen, C1-3 alkyl group, C1-3 halogenated alkyl group, and combinations thereof. The t is an integer from 0 to 4, and the z is an integer from 0 to 3.

Among the repeating units of polyamide or polyester represented by the formula (22), those represented by the following general formula (23) are preferable.

  In the formula (23), A, A ′ and Y are those defined in the formula (22), and v is an integer of 0 to 3, preferably an integer of 0 to 2. x and y are each 0 or 1, but are not 0 at the same time.

  In addition, examples of the polyamideimide include polyamideimide described in JP-A No. 61-162512.

  Examples of the polyamic acid include polymers represented by the following formulas (10) to (12).

In said formula, n is an average degree of polymerization, and shows the number of 2-400.
In addition, when using the said polyamic acid, it is preferable to imidize by heat processing, after apply | coating a solution and drying.

[Polarizer]
The present invention also relates to a linearly polarizing film (in the present specification, the term “polarizing film” simply refers to a “linearly polarizing film”) and a retardation film of the present invention as a protective film for the polarizing film. It also relates to a polarizing plate having Since the retardation film of the present invention has a predetermined cellulose acylate film as a support, the back surface of the cellulose acylate film (the surface on which the optically anisotropic layer is not formed) is directly applied to the surface of the polarizing film. Can be pasted together. For example, a continuous cellulose acylate film is continuously supplied, and a polymerizable liquid crystal composition or a polymer layer forming composition is applied to the surface of the film to form an optically anisotropic layer. By producing a long retardation film and further laminating it with a long polarizing film, a polarizing plate can be continuously produced stably.

[Polarizing film]
The polarizing film employed in the present invention is not particularly limited, and known materials can be widely employed. For example, films made of hydrophilic polymers such as polyvinyl alcohol, partially formalized polyvinyl alcohol, partially saponified ethylene / vinyl acetate copolymer, dichroic dyes such as iodine and / or azo, anthraquinone and tetrazine A material obtained by adsorbing a dichroic material composed of the above material and subjecting it to stretching and orientation can be used. In the present invention, it is preferable to use the stretching method described in JP-A No. 2002-131548, and in particular, a width direction uniaxial stretching type tenter stretching machine in which the absorption axis of the polarizing film is substantially perpendicular to the longitudinal direction. It is preferable to use it.

The polarizing film is used as a polarizing plate whose both surfaces are protected by protective films. As will be described later, the retardation film of the present invention is preferably used as a protective film for a polarizing film.
When a protective film other than the retardation film of the present invention is used as the protective film, the type of the protective film is not particularly limited, and cellulose esters such as cellulose acetate, cellulose acetate butyrate, and cellulose propionate, polycarbonate, polyolefin, Polystyrene, polyester, etc. can be used. The protective film is usually supplied in a roll form, and it is preferable that the protective film is continuously bonded to the long polarizing film so that the longitudinal directions thereof coincide. Here, the orientation axis (slow axis) of the protective film may be any direction, but the orientation axis of the protective film is preferably parallel to the longitudinal direction from the operational convenience. Further, the angle between the slow axis (alignment axis) of the protective film and the absorption axis (stretching axis) of the polarizing film is not particularly limited, and can be appropriately set according to the purpose of the polarizing plate.

  When a protective film other than the retardation film of the present invention is used as the protective film, the Re value of the protective film is, for example, preferably 10 nm or less at 632.8 nm, and more preferably 5 nm or less. From the viewpoint of such a low retardation, polyolefins such as cellulose triacetate, ZEONEX, ZEONOR (both manufactured by Nippon Zeon Co., Ltd.), and ARTON (manufactured by JSR Co., Ltd.) are preferably used as the protective film. . Other examples include non-birefringent optical resin materials as described in JP-A-8-110402 or JP-A-11-293116. When cellulose acetate is used for the protective film, Re and Rth are preferably less than 10 nm, and more preferably 2 nm or less, for the purpose of reducing a change in retardation due to environmental temperature and humidity.

  In the present invention, for the purpose of reducing the thickness, one of the protective films of the polarizing film may also serve as the support for the optically anisotropic layer, or the optically anisotropic layer itself. The optically anisotropic layer and the polarizing film are preferably subjected to a fixing treatment from the viewpoint of preventing displacement of the optical axis and preventing entry of foreign matters such as dust. An appropriate method such as an adhesive method through a transparent adhesive layer can be applied to the fixed lamination. There is no particular limitation on the type of the adhesive and the like, and from the viewpoint of preventing changes in the optical properties of the constituent members, those that do not require a high-temperature process during curing or drying are preferable, and a long-time curing process is preferable. And those that do not require drying time. From such a viewpoint, a hydrophilic polymer adhesive or a pressure-sensitive adhesive layer is preferably used.

  For the formation of the pressure-sensitive adhesive layer, for example, a transparent pressure-sensitive adhesive using an appropriate polymer such as an acrylic polymer, a silicone-based polymer, polyester, polyurethane, polyether, or synthetic rubber can be used. Among these, acrylic pressure-sensitive adhesives are preferred from the viewpoints of optical transparency, adhesive properties, weather resistance, and the like. In addition, an adhesion layer can also be provided as needed on one side or both sides of a polarizing plate for the purpose of adhesion to an adherend such as a liquid crystal cell. In that case, 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.

  Appropriate functional layers such as a protective film for various purposes such as water resistance according to the above protective film, an antireflection layer and / or an antiglare treatment layer for the purpose of preventing surface reflection, etc. on one or both sides of the polarizing film You may use the polarizing plate which formed. The antireflection layer can be suitably formed, for example, as a light interference film such as a fluorine polymer coating layer or a multilayer metal vapor deposition film. The antiglare layer is also formed by an appropriate method that diffuses the surface reflected light, for example, by providing a fine uneven structure on the surface by an appropriate method such as a resin coating layer containing fine particles, embossing, sandblasting or etching. can do.

  Examples of the fine particles include inorganic materials such as silica, calcium oxide, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, and antimony oxide having an average particle size of 0.5 to 20 μm. One kind or two or more kinds of fine particles, such as crosslinked or uncrosslinked organic fine particles made of a suitable polymer such as polymethyl methacrylate and polyureta can be used. The above-mentioned adhesive layer or pressure-sensitive adhesive layer may contain such fine particles and exhibit light diffusibility.

[Optical performance of polarizing plate]
The polarizing plate of the present invention includes a polarizing film and a protective film (at least one of the retardation films of the present invention). The optical properties and durability (short-term and long-term storage stability) of the polarizing plate of the present invention should be equal to or better than those of a commercially available super high contrast product (for example, HLC2-5618 manufactured by Sanlitz Co., Ltd.). Is preferred. Specifically, the visible light transmittance is 42.5% or more, and the degree of polarization ({(Tp−Tc) / (Tp + Tc)} ^1/2 ≧ 0.9995 (where Tp is parallel transmittance and Tc is orthogonal) The change rate of the light transmittance before and after leaving for 500 hours in a 60 ° C., 90% humidity RH atmosphere and 500 ° C. in a dry atmosphere for 500 hours is 3% based on the absolute value. In the following, it is further preferable that the change rate of the polarization degree is 1% or less, further 0.1% or less based on the absolute value.

The polarizing plate of the present invention may have another retardation film (second retardation film) together with the retardation film (first retardation film) of the present invention. Preferred optical characteristics of the second retardation film vary depending on the mode of the liquid crystal display device in which the polarizing plate of the present invention is used. For example, when used in a vertical alignment type liquid crystal display device such as a VA mode, the second retardation film is preferably an A plate, and more specifically, a retardation film satisfying the following formula [7]. Is preferred. Furthermore, it is more preferable that the wavelength dispersibility satisfies the following formula [8].
[7] 70 ≦ Re (550) ≦ 180 and 30 ≦ Rth (550) ≦ 140
[8] 0.7 ≦ Re (450) / Re (550) ≦ 1.0
The second retardation film is preferably laminated so that the in-plane slow axis thereof is perpendicular to the absorption axis of the polarizing film.
Details of the second retardation film will be described in the following [Liquid Crystal Display] column.

[Liquid Crystal Display]
The present invention also relates to a liquid crystal display device having the retardation film or polarizing plate of the present invention. The liquid crystal display device of the present invention is a vertical alignment type in which liquid crystal molecules in a liquid crystal cell are aligned perpendicular to a substrate in a non-driving state where a driving voltage is not applied or a voltage less than the applied voltage is applied. For example, it is preferable to include liquid crystal cells such as VA mode, MVA mode, PVA mode, CPA mode, and SUVIVAL mode. Hereinafter, an embodiment of the liquid crystal display device of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic view of an example of the configuration of a liquid crystal display device of the present invention, and FIG. 2 shows an example of the structure of a polarizing plate that can be used in the present invention. FIG. 1 shows an example in which active driving is performed using a nematic liquid crystal having negative dielectric anisotropy as a field effect liquid crystal element.

  In FIG. 1, the liquid crystal display device includes a liquid crystal cell and a pair of polarizing plates (an upper polarizing plate 1 and a lower polarizing plate 14) disposed on both sides of the liquid crystal cell. A second retardation film 3 is disposed between the upper polarizing plate 1 and the liquid crystal cell, and a first retardation film 10 is disposed between the lower polarizing plate 14 and the liquid crystal cell. The liquid crystal cell includes an upper electrode substrate 5, a lower electrode substrate 8, and liquid crystal molecules 7 sandwiched between them. The liquid crystal molecules 7 are aligned with respect to the substrate in an undriven state in which no external electric field is applied by the alignment control directions (upper substrate alignment control direction 6 and lower substrate alignment control direction 9) applied to the opposing surface of the electrode substrate. To be oriented in a substantially vertical direction. Further, the upper polarizing plate 1 and the lower polarizing plate 14 are laminated so that the absorption axis and the absorption axis are substantially orthogonal to each other. In FIG. 1, 2 represents the direction of the upper polarizing plate absorption axis, and 15 represents the direction of the lower polarizing plate absorption axis. Further, the second retardation film is arranged with the slow axis direction 4 orthogonal to the absorption axis direction 2 of the upper polarizing plate.

  As shown in FIG. 2, the polarizing plate includes a polarizing film 103 sandwiched between protective films 101 and 105. The polarizing plate can be produced, for example, by dyeing a polarizing film made of a polyvinyl alcohol film with iodine and drawing it to obtain a polarizing film, and laminating protective films 101 and 106 on both sides thereof. In the case of lamination, it is preferable in terms of productivity when a total of three films including a pair of protective films and a polarizing film are bonded together in a roll-to-roll manner. Also, in the roll-to-roll lamination, as shown in FIG. 2, the slow axis directions 102 and 106 of the protective film can be easily laminated so that the absorption axis direction 104 of the polarizing film is parallel. It is preferable because a dimensional change of the plate and occurrence of curling hardly occur and the polarizing plate has high mechanical stability. The same effect can be obtained if at least two axes of three films, for example, the slow axis and polarizing film absorption axis of one protective film or the slow axes of two protective films are substantially parallel. Is obtained.

  In FIG. 1, the first retardation film 10 is the retardation film of the present invention, and details are as described above. When disposing the retardation film of the present invention as the first retardation film, the support, which is a predetermined cellulose acylate film, is disposed on the polarizing plate side, and the optically anisotropic layer is disposed on the liquid crystal cell side. Is preferred. Moreover, it replaces with arrange | positioning a 1st phase difference film, and the same effect is acquired even if it arrange | positions the polarizing plate of this invention as the polarizing plate 1. FIG. In addition, when incorporating the polarizing plate of the present invention into a liquid crystal display device, the retardation film of the present invention incorporated as a protective film in the polarizing plate is disposed so as to be on the liquid crystal cell side.

  In FIG. 1, the second retardation film 3 is optically composed of a uniaxial or biaxial optically anisotropic layer, and is not particularly limited. However, cellulose acylate, norbornene polymer, polycarbonate polymer, Examples include polyarylate polymers, polyester polymers, polysulfone, or polymers obtained by mixing two or more of these polymers. Among them, those excellent in controllability of birefringence characteristics, transparency and heat resistance are preferable. In addition, the second retardation film 3 depends on the combination with the first retardation film 10, but from the viewpoint of display characteristics, the absolute value of Re increases with the wavelength, so-called reverse wavelength dispersion. More preferably, it is uniaxial. On the other hand, the first retardation film 10 has optically negative refractive index anisotropy, and the absolute value of Rth decreases with the wavelength, so-called forward wavelength dispersion, and Re is −10 to 10 nm. It is preferable. The second retardation film 3 and the first retardation film 10 eliminate the image coloring of the liquid crystal cell and contribute to the expansion of the viewing angle.

  In FIG. 1, when the upper side is an observer side, in FIG. 1, the second retardation film 3 is an upper polarizing plate 1 on the observer side and an observer side liquid crystal cell substrate. 5, the first retardation film 10 is configured to be disposed between the lower polarizing plate 14 on the back side and the liquid crystal cell lower electrode substrate 8 which is the back side liquid crystal cell substrate. The second retardation film 3 and the first retardation film 10 may be interchanged, and both the second retardation film 3 and the first retardation film 10 may be on the upper side. It may be disposed between the polarizing plate 1 and the upper electrode substrate 5 of the liquid crystal cell, or may be disposed between the lower polarizing plate 14 and the lower electrode substrate 8 of the liquid crystal cell. In such an embodiment, the first retardation film 10 may also serve as a support for the second retardation film 3.

  The retardation film may be integrated with the polarizing plate. For example, in FIG. 1, the second retardation film 3 may be integrated with the upper polarizing plate 1. In this case, it can be incorporated into the liquid crystal display device in an integrated state with the upper polarizing plate 1. For example, the support for the second retardation film may function as a protective film on one side of the polarizing film, and the integrated polarizing plate in which the protective film, the polarizing film, and the second retardation film are laminated in this order It is preferable to do this. When the integrated polarizing plate is incorporated in the liquid crystal display device, it is preferable to incorporate the protective film, the polarizing film, and the second retardation film 3 in this order from the outside of the device (the side far from the liquid crystal cell). .

  Moreover, the polarizing plate of this invention can also be used as the upper polarizing plate 1, Furthermore, as above-mentioned, the 2nd phase difference film 3 may also be integrated with the polarizing plate of this invention, and may be integrated in a liquid crystal display device. In such an embodiment, the integrated polarizing plate is laminated in the order of the protective film, the polarizing film, the first retardation film (in the order of the support and the optically anisotropic layer), and the second retardation film. The polarizing plate is preferably incorporated in the liquid crystal display device from the outside (the side far from the liquid crystal cell) in the order of the protective film, the polarizing film, the first retardation film, and the second retardation film.

The second retardation film will be described in more detail.
[Second retardation film]
In the liquid crystal display device of the present invention, particularly the vertical alignment type liquid crystal display device, it is preferable to use the second retardation film together with the first retardation film which is the retardation film of the present invention. Here, the front retardation and the retardation in the thickness direction of the second retardation film satisfy the following formula [6], and / or the wavelength dispersion of the second retardation film satisfies the following formula [7]. It is preferable to satisfy.
[7] 70 ≦ Re (550) ≦ 180 and 30 ≦ Rth (550) ≦ 140
[8] 0.7 ≦ Re (450) / Re (550) ≦ 1.0
The second retardation film that can be used in the present invention may be optically uniaxial or biaxial. The second retardation film that can be used in the present invention may be a polymer film or a layer formed from a polymerizable liquid crystal composition, and can obtain desired properties. If there is no particular restriction. The polymer to be used is not particularly limited as long as uniform biaxial orientation can be achieved. For example, norbornene polymer, polycarbonate polymer, polyarylate polymer, polyester polymer, polysulfone, etc. Aromatic polymers, triacetyl cellulose, and the like that can be formed by a solution casting method, an extrusion molding method, or the like. A biaxial optically anisotropic layer is a film produced by an appropriate method such as an extrusion molding method or a casting film forming method, such as a longitudinal stretching method using a roll, a transverse stretching method using a tenter, a biaxial stretching method, etc. Thus, it can be formed by stretching.

The Re value of the second retardation film that can be used in the present invention is preferably 80 to 170 nm, and more preferably 90 to 160 nm. Further, the value of Rth is preferably 40 to 120 nm, more preferably 50 to 100 nm.
The wavelength dispersibility represented by Re (450) / Re (550) is preferably 0.73 to 0.95, and more preferably 0.75 to 0.90.

  In the longitudinal stretching method using the roll, a heating method such as a method using a heating roll, a method of heating an atmosphere, or a method of using them together can be employed. Moreover, in the biaxial stretching method using a tenter, methods such as a simultaneous biaxial stretching method using an all tenter method and a sequential biaxial stretching method using a roll tenter method can be employed. Moreover, a thing with little orientation nonuniformity and phase difference nonuniformity is preferable. Although the thickness can be appropriately determined depending on the phase difference or the like, generally 1 to 300 μm is preferable, 10 to 200 μm is more preferable, and 20 to 150 μm is more preferable from the viewpoint of thinning.

  Examples of norbornene-based polymers that can be used for the production of the second retardation film include norbornene-based derivatives such as norbornene and derivatives thereof, tetracyclododecene and derivatives thereof, dicyclopentadiene and derivatives thereof, and methanotetrahydrofluorene and derivatives thereof. Examples thereof include a polymer of a monomer having a monomer as a main component. For example, a ring-opening polymer of a norbornene monomer, a ring-opening copolymer of a norbornene monomer and another monomer capable of ring-opening copolymerization, an addition polymer of a norbornene monomer, and a norbornene monomer and a copolymer thereof Examples include addition copolymers with other possible monomers, and hydrogenated products thereof. Among these, from the viewpoints of heat resistance, mechanical strength, and the like, a ring-opening polymer hydride of a norbornene monomer is most preferable. The molecular weight of the norbornene-based polymer, the monocyclic olefin polymer or the cyclic conjugated diene polymer is appropriately selected according to the purpose of use. For example, it is a polyisoprene or polystyrene-converted weight average molecular weight measured by gel permeation chromatography of a cyclohexane solution (or a toluene solution when the polymer resin does not dissolve), preferably 5,000 to 500,000. More preferably, it is the range of 8,000-200,000, More preferably, it is the range of 10,000-100,000. When the average molecular weight is such, the mechanical strength and molding processability of the film of the optically anisotropic layer obtained are highly balanced and suitable.

  Examples of the polycarbonate polymer that can be used to produce the second retardation film include a mixture of polycarbonate and other polymers.

  Examples of the polyarylate polymer that can be used for the production of the second retardation film include polyoxybenzoate and the like and mixtures with other polymers.

  Polyester polymers that can be used to produce the second retardation film include polyethylene terephthalate, polyethylene isophthalate, polyphenylene isophthalate, polybutylene terephthalate, polyethylene-2.6-naphthalate, and other polymers and mixtures thereof. Is mentioned.

  Examples of the aromatic polymer such as polysulfone that can be used for the production of the second retardation film include polysulfone, polyethersulfone, polyallylsulfone, and the like and mixtures with other polymers.

  The glass transition temperature Tg of the polymer that can be used for the production of the second retardation film is appropriately determined according to the purpose of use. The glass transition temperature of the resin is preferably 70 ° C or higher, more preferably 80 ° C to 250 ° C, and still more preferably 90 ° C to 200 ° C. When a resin in this range is employed, heat resistance and molding processability are highly balanced, which is preferable.

  As the second retardation film, the most preferable examples are JP-A No. 2000-137116, JP-A No. 2002-14234, JP-A No. 2002-48919, WO 00/26705 pamphlet, JP-A No. 2 A stretched polymer film or a composite stretched film in which retardation has reverse wavelength dispersion characteristics as disclosed in JP-A No. 120804 can be used. Typically, a polycarbonate film having a fluorene skeleton produced by stretching a film containing liquid crystal, a cellulose acetate film produced by stretching the film, an aromatic polyester polymer having a positive wavelength dispersion characteristic, and a reverse wavelength dispersion A film made of a mixture with a characteristic aromatic polyester polymer and stretched, or a polymer made of a copolymer containing monomer units that form a polymer with different wavelength dispersion characteristics. There are a film, a composite film in which two stretched films having different wavelength dispersion characteristics are laminated, and the like.

  As a method for forming the resin into a sheet or film, for example, either a hot melt molding method or a solution casting method can be used. The heat-melt molding method can be further classified into an extrusion molding method, a press molding method, an inflation molding method, an injection molding method, a blow molding method, a stretch molding method, etc. Among these methods, mechanical strength, surface In order to obtain a film excellent in accuracy and the like, the extrusion molding method, the inflation molding method, and the press molding method are preferable, and the extrusion molding method is most preferable. The molding conditions are appropriately selected depending on the purpose of use and the molding method. In the case of the heat-melt molding method, the cylinder temperature is preferably set in the range of preferably 100 to 400 ° C, more preferably 150 to 350 ° C. The thickness of the sheet or film is preferably 10 to 300 μm, more preferably 30 to 200 μm.

  The stretching of the sheet or film is preferably a temperature range of (Tg-30) ° C. to (Tg + 60) ° C., more preferably (Tg−60), where Tg is the glass transition temperature of the polymer employed in the optically anisotropic layer. It is carried out at a temperature of Tg-10) ° C. to (Tg + 50) ° C. in at least one direction, preferably at a draw ratio of 1.01 to 2 times. When the sheet is obtained by extrusion molding, the stretching direction is preferably the mechanical flow direction (extrusion direction) of the resin. The stretching method is preferably a free shrink uniaxial stretching method, a fixed width uniaxial stretching method, a biaxial stretching method, or the like.

Here, an example of a specific method of stretching will be given.
(1) The sheet is adjusted to a desired temperature by passing it through a roll (heated roll) heated to a constant temperature.
(2) Next, the temperature-adjusted sheet is stretched by passing through a first roll having a relatively low rotation speed and a second roll having a higher rotation speed. By controlling the speed ratio between the rotation speed of the first roll and the rotation speed of the second roll, the draw ratio can be adjusted in the range of 1 to 4 times. In addition, it is preferable to install an infrared heater etc. between a heating roll, a 1st roll, and a 2nd roll, and hold | maintain the temperature of a sheet | seat constant.
(3) The stretched film is cooled through a cooling roll.
(4) The cooled stretched film is collected with a winding roll. For the purpose of preventing blocking between films due to winding, a masking film having the same width as the stretched film may be stacked and wound together, or at least one end of the stretched film, preferably both ends, You may wind together, sticking thin tape etc. of weak adhesive strength.
In the step (1) of the above method, the sheet passing through the heating roll may be in a state where the temperature is higher than that of the heating roll, that is, a state immediately after being formed by an extruder or the like. Moreover, since it can be made into a high draw ratio, the thing of temperature lower than a heating roll and room temperature (for example, 25-30 degreeC) may be sufficient. Preferably, it is room temperature. Such a low-temperature sheet can be obtained by forming a sheet, cooling it once, and winding and collecting it on a roll. The stretching speed is preferably 5 to 1000 mm / second, more preferably 10 to 750 mm / second. When the stretching speed is in the above range, stretching control becomes easy, and further, surface accuracy and in-plane variation of retardation can be further reduced.

  The liquid crystal display device of the present invention is not limited to the above configuration, and may include other members. For example, a color filter may be disposed between the liquid crystal cell and the polarizing film. In the transmissive liquid crystal display device, a backlight using a cold or hot cathode fluorescent tube, a light emitting diode, or an electroluminescent element as a light source can be disposed on the back surface. On the other hand, in the aspect of the reflective liquid crystal display device, only one polarizing plate needs to be disposed on the observation side, and a reflective film is provided on the back surface of the liquid crystal cell or the inner surface of the lower substrate of the liquid crystal cell. Of course, it is also possible to provide a front light using the light source on the liquid crystal cell observation side. Further, a transflective type in which a transmissive portion and a reflective portion are provided in one pixel of the display device is also possible.

  The type of the liquid crystal display device of the present invention is not particularly limited, and includes any of image direct view type, image projection type, and light modulation type liquid crystal display devices. An active matrix liquid crystal display device using a three-terminal or two-terminal semiconductor element such as TFT or MIM is particularly effective in the present invention. Of course, the present invention is also effective in a passive matrix liquid crystal display device represented by a super-twisted nematic type (STN type) called time-division driving.

[VA mode liquid crystal cell]
In the present invention, the liquid crystal cell is preferably in a vertically aligned mode (VA mode). In a VA mode liquid crystal cell, liquid crystal molecules are aligned in a direction substantially perpendicular to the substrate of the liquid crystal cell in a non-driven state where an external electric field is not applied. Such a liquid crystal cell is formed, for example, by enclosing liquid crystal molecules having negative dielectric anisotropy between upper and lower electrode substrates whose opposing surfaces are rubbed.
More specifically, using a liquid crystal molecule having Δn = 0.0813 and Δε = −4.6, a director indicating the alignment direction of the liquid crystal molecule, that is, a liquid crystal cell having a so-called tilt angle of about 89 ° can be manufactured. it can. At this time, the thickness d of the liquid crystal layer can be set to 3.5 μm, for example. The brightness at the time of white display changes depending on the magnitude of the product Δn · d of the thickness d (nm) of the liquid crystal layer and the refractive index anisotropy Δn. In order to obtain the maximum brightness, the thickness d of the liquid crystal layer is preferably in the range of 2 to 5 μm (2000 to 5000 nm), and Δn is preferably in the range of 0.060 to 0.085. . Here, the refractive index anisotropy Δn is Δn = Rth / film thickness (nm).
It is represented by

  When the liquid crystal display device shown in FIG. 1 has a VA mode liquid crystal cell, a transparent electrode (not shown) is formed inside the liquid crystal cell upper electrode substrate 5 and the liquid crystal cell lower electrode substrate 8. In a non-driving state in which no driving voltage is applied to the liquid crystal molecules, the liquid crystal molecules 7 in the liquid crystal layer are aligned substantially perpendicular to the substrate surface, and as a result, the polarization state of light passing through the liquid crystal panel hardly changes. As described above, the direction 2 of the upper polarizing plate absorption axis of the liquid crystal cell and the direction 15 of the lower polarizing plate absorption axis are substantially orthogonal, so that light does not pass through the polarizing plate. That is, the liquid crystal display device of FIG. 1 realizes an ideal black display in the non-driven state. On the other hand, in the driving state, the liquid crystal molecules are inclined in a direction parallel to the substrate surface, and the light passing through the liquid crystal panel changes the polarization state by the inclined liquid crystal molecules and passes through the polarizing plate.

  In FIG. 1, since an electric field is applied between the upper and lower substrates, an example in which a liquid crystal material having a negative dielectric anisotropy in which liquid crystal molecules respond perpendicularly to the electric field direction is shown. In the case where an electrode is disposed on one substrate and an electric field is applied in a lateral direction parallel to the substrate surface, a liquid crystal material having a positive dielectric anisotropy can be used. Note that in a VA mode liquid crystal display device, the addition of a chiral agent generally used in a twisted nematic mode (TN mode) liquid crystal display device is rarely used to degrade dynamic response characteristics. Sometimes added to reduce defects.

  The characteristics of the VA mode are high-speed response and high contrast. However, there is a problem that the contrast is high in the front but decreases in the oblique direction. During black display, the liquid crystal molecules are aligned perpendicular to the substrate surface. When observed from the front, the liquid crystal molecules have almost no birefringence, so the transmittance is low and a high contrast can be obtained. However, when observed obliquely, birefringence occurs in the liquid crystal molecules. Further, the crossing angle of the upper and lower polarizing plate absorption axes is 90 ° perpendicular to the front, but is larger than 90 ° when viewed from an oblique direction. Due to these two factors, leakage light tends to occur in the oblique direction, and the contrast tends to decrease. In this invention, in order to solve this, at least one retardation film of this invention is arrange | positioned. It is preferable to arrange at least one layer each of the retardation film and the second retardation film of the present invention.

  In the VA mode, the liquid crystal molecules are tilted during white display, but the birefringence of the liquid crystal molecules when viewed from an oblique direction is different between the tilt direction and the opposite direction, resulting in differences in luminance and color tone. In order to solve this, the liquid crystal cell is preferably multi-domain. Multi-domain refers to a structure in which a plurality of regions having different alignment states are formed in one pixel. For example, in a multi-domain type VA mode liquid crystal cell, a plurality of regions having different tilt angles of liquid crystal molecules when an electric field is applied exist in one pixel. In a multi-domain VA mode liquid crystal cell, the tilt angle of liquid crystal molecules due to application of an electric field can be averaged for each pixel, whereby the viewing angle characteristics can be averaged. In order to divide the orientation within one pixel, the electrode is provided with slits or protrusions, and the electric field direction is changed or the electric field density is biased. In order to obtain a uniform viewing angle in all directions, the number of divisions may be increased.

  Also, the liquid crystal molecules are difficult to respond at the alignment division region boundary. For this reason, in normally black display, since black display is maintained, a reduction in luminance becomes a problem. Adding a chiral agent to the liquid crystal material contributes to reducing the boundary region.

  The present invention will be described more specifically with reference to the following examples. The materials, reagents, amounts and ratios of substances, operations, and the like shown in the following examples can be appropriately changed without departing from the gist of the present invention. Therefore, the scope of the present invention is not limited to the following specific examples.

[Example 1]
<Production of liquid crystal cell>
(Preparation of vertical alignment liquid crystal cell)
1% by mass of octadecyldimethylammonium chloride (coupling agent) was added to a 3% by mass aqueous polyvinyl alcohol solution. This was spin-coated on a glass substrate with an ITO electrode, heat-treated at 160 ° C., and then rubbed to form a vertical alignment film. The rubbing treatment was performed so that the two glass substrates were in opposite directions. Two glass substrates were faced to each other so that the cell gap (d) was about 5.0 μm. A liquid crystal compound (Δn: 0.06) mainly composed of ester and ethane was injected into the cell gap to produce a vertically aligned liquid crystal cell. The product of Δn and d was 300 nm.

<Preparation of support 1>
The support 1 was produced by the method described below.
(Production of polymer 1)
The following composition is put into a four-necked flask (installed with an inlet, a thermometer, a reflux condenser, a nitrogen inlet, and a stirrer), gradually heated to 80 ° C., and polymerized for 5 hours while stirring. After completion, the polymer solution was poured into a large amount of methanol to precipitate, further washed with methanol, purified and dried to obtain polymer 1 (acrylate polymer) having a weight average molecular weight of 3,000 (measured by GPC).
Methyl acrylate 10 parts by mass 2-hydroxyethyl acrylate 1 part by mass Azobisisobutyronitrile (AIBN) 1.5 parts by mass Toluene 30 parts by mass

(Film formation of support 1)
The following dope composition was put into a pressure sealed container and heated to 70 ° C. to bring the pressure in the container to 1 atm or more, and the cellulose ester was completely dissolved while stirring. The dope temperature was lowered to 35 ° C. and allowed to stand overnight, and this dope was added to Azumi filter paper No. 1 manufactured by Azumi Filter Paper Co., Ltd. After filtration using 244, the mixture was further left standing overnight to degas. Next, a filtration pressure of 1.0 using Finemet NM (absolute filtration accuracy 100 μm) and Finepore NF (absolute filtration accuracy 50 μm, 15 μm, 5 μm in order of absolute filtration accuracy) manufactured by Nippon Seisen Co., Ltd. It filtered by * 10 < ⁶ > Pa and used for film forming.

(Dope composition)
Cellulose triacetate (degree of substitution 2.83) 100 parts by mass Polymer 1 15 parts by mass The following UV agent (1) 0.8 parts by mass The following UV agent (2) 0.2 parts by mass Methylene chloride 475 parts by mass Ethanol 50 parts by mass Part

The thickness of the produced support 1 was 80 μm.
The obtained film had an in-plane retardation Re (630) of 2 nm, a thickness direction retardation Rth (630) of −7 nm, | Re (400) −Re (700) | of 3 nm, and Rth. (400) -Rth (700) was -25 nm.

<Preparation of Support 2>
The support 2 was produced by the method described below.
(Production of polymer 2)
Polymer 2 (acrylate polymer) was synthesized in the same manner as Polymer 1 using the following composition. The weight average molecular weight of the polymer 2 was 2,000.
Methyl methacrylate 6 parts by mass Ethyl methacrylate 5 parts by mass 2-hydroxyethyl acrylate 1 part by mass Azobisisobutyronitrile (AIBN) 2 parts by mass Toluene 30 parts by mass

(Film formation of support 2)
A support 2 was produced in the same manner as the support 1 except that the polymer 1 in the dope composition was replaced with the polymer 2.
The thickness of the produced support 2 was 80 μm.
The in-plane retardation Re (630) of the obtained film was 2 nm, the retardation Rth (630) in the thickness direction was −5 nm, | Re (400) −Re (700) | was 2 nm, and Rth (400) -Rth (700) was -20 nm.

<Preparation of support 3>
A support 3 was produced in the same manner as the support 2 except that the thickness of the support was changed to 40 μm.
The in-plane retardation Re (630) of the obtained film is 2 nm, the retardation Rth (630) in the thickness direction is −5 nm, | Re (400) −Re (700) | is 2 nm, and Rth ( 400) -Rth (700) was -20 nm.

<Preparation of support 4>
The support 4 was produced by the method described below.

(Film formation of support 4)
A support 4 was produced in the same manner as the support 1 except that the following dope composition was changed to the following composition.
(Dope composition)
Cellulose triacetate (degree of substitution 2.90) 100 parts by weight Polymer 1 of the above synthesis 10 parts by weight of triphenyl phosphate 4 parts by weight of biphenyl diphenyl phosphate 2 parts by weight of the above UV agent (1) 0.8 part by weight of the above UV agent (2) 0 .2 parts by mass Methylene chloride 475 parts by mass Ethanol 50 parts by mass The thickness of the produced support 4 was 80 μm.
The in-plane retardation Re (630) of the obtained film was 3 nm, the retardation Rth (630) in the thickness direction was −5 nm, | Re (400) −Re (700) | was 2 nm, and Rth (400 ) -Rth (700) was -13 nm.

<Preparation of support 5>
The support 5 was produced by the method described below.
(Film formation of support 5)
A support 5 was produced in the same manner as the support 1 except that the following dope composition was changed to the following composition.
(Dope composition)
Cellulose triacetate (degree of substitution 2.92) 100 parts by weight UMM-1001 (acrylic polymer) 20 parts by weight The following UV agent (3) 1.4 parts by weight methylene chloride 475 parts by weight Ethanol 50 parts by weight

UMM-1001: manufactured by Toa Gosei Co., Ltd., Actflow

The thickness of the produced support 5 was 80 μm.
The in-plane retardation Re (630) of the obtained film was 2 nm, the retardation Rth (630) in the thickness direction was 5 nm, | Re (400) −Re (700) | was 1 nm, and Rth (400) -Rth (700) was 20 nm.

<Preparation of the first retardation film 1>
After saponification of the surface of the support 1, an alignment film coating solution having the following composition was 20 ml / m ² coated with a wire bar coater on the film. The film was formed by drying with warm air of 60 ° C. for 60 seconds and further with warm air of 100 ° C. for 120 seconds. Next, the formed film was rubbed in a direction parallel to the slow axis direction of the film to form an alignment film.
Composition of alignment film coating solution ―――――――――――――――――――――――――――――――――――
Denatured polyvinyl alcohol 10 parts by weight Water 371 parts by weight Methanol 119 parts by weight Glutaraldehyde 0.5 parts by weight Compound B 0.2 parts by weight ―――――――――――――――――――― ―――――――――――――――

Next, an optically anisotropic layer coating solution having the following composition was applied with a wire bar so that the Rth in the thickness direction after curing was 200 nm.
Optically anisotropic layer coating solution ―――――――――――――――――――――――――――――――――――
The following discotic liquid crystalline compound 1.8g
Ethylene oxide modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.) 0.2 g
Photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) 0.06 g
Sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 0.02g
Fluorine-containing polymer (compound A below) 0.01g
Methyl ethyl ketone 3.9g
―――――――――――――――――――――――――――――――――――

Discotic liquid crystalline compounds

Compound A

  This was affixed to a metal frame and heated in a thermostatic bath at 125 ° C. for 3 minutes to align the discotic liquid crystalline compound. Next, using a 120 W / cm high-pressure mercury lamp, UV irradiation was performed for 30 seconds to crosslink the discotic liquid crystalline compound. The temperature at the time of UV curing was set to 80 ° C. to obtain a retardation film. The thickness of the optically anisotropic layer was 2.9 μm. Then, it stood to cool to room temperature. Thus, the retardation film 1 was produced. The optical characteristics of the retardation film 1 are shown in Table 1.

<Production of first retardation films 2 to 5>
Next, the first retardation films 2 to 5 were produced in the same manner as the first retardation film 1 except that the coating amount of the optically anisotropic layer coating solution was changed. The thickness of the optically anisotropic layer of the obtained first retardation film was 3.6 μm, 2.2 μm, 0.8 μm, and 5.0 μm in order. The optical properties of the produced retardation film are shown in Table 1.

<Preparation of the first retardation film 6>
Next, a commercially available cellulose acetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd., Re (630) = 3 nm, Rth (630) = 45 nm, Re (400) -Re (700) =-5 nm, Rth (400) −Rth (700) = − 13 nm) was used, and the first retardation film 6 was produced in the same manner as the first retardation film 1 except that the coating film thickness was adjusted.
The optical properties of the produced retardation film are shown in Table 1.

<Preparation of the first retardation film 7>
75 parts of a rod-like liquid crystalline compound having a polymerizable acrylate group at both ends and having a spacer between the mesogen and acrylate at the center, 1 mass of a photopolymerization initiator (manufactured by Chiba Specialty Chemicals, Irgacure Irg184) And 25 parts by mass of methyl ethyl ketone as a solvent were mixed, and 10 parts by mass of a chiral agent having polymerizable acrylate groups at both ends was added as a chiral agent to prepare an optically anisotropic layer coating solution.

Rod-like liquid crystalline compound

ここで、ｘは４である。 Chiral agent

Here, x is 4.

  Similarly to the first retardation film, the prepared optically anisotropic layer coating solution is saponified and coated with an alignment film on the support 1, and further applied to the rubbed alignment film surface, dried and UV cured. A chiral nematic (cholesteric) liquid crystal layer (optically anisotropic layer) was obtained. The thickness of the obtained optically anisotropic layer was 4.2 μm. The spiral pitch of the liquid crystal layer was 180 nm, and the reflection wavelength was 280 nm. The optical properties of the produced retardation film are shown in Table 1.

<Preparation of the first retardation film 8>
Next, a first retardation film 8 was produced in the same manner as the first retardation film 7 except that the support 2 was used. The optical properties of the produced retardation film are shown in Table 1.

<Preparation of the first retardation film 9>
Next, a first retardation film 9 was produced in the same manner as the first retardation film 7 except that the support 3 was used. The optical properties of the produced retardation film are shown in Table 1.

<Preparation of the first retardation film 10>
Next, a first retardation film 10 was produced in the same manner as the first retardation film 7 except that the support 4 was used. The optical properties of the produced retardation film are shown in Table 1.

<Preparation of the first retardation film 11>
Next, a first retardation film 11 was produced in the same manner as the first retardation film 7 except that the support 5 was used. The optical properties of the produced retardation film are shown in Table 1.

<Preparation of the first retardation film 12>
Next, a commercially available cellulose acetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) was used as a support, and the first retardation film 7 was used except that the coating film thickness was adjusted. A retardation film 12 was prepared.

<Preparation of the first retardation film 13>
Weight average molecular weight (Mw) synthesized from 2,2′-bis (3,4-dicarboxyphenyl) hexafluoropropane and 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl A 120,000 polyimide solution was prepared by dissolving 120,000 polyimide in cyclohexanone. Then, the polyimide solution was applied on the support 4. And as a result of drying-processing this coating film at 100 degreeC for 10 minute (s), the 5 micrometer-thick polyimide film was formed. In this way, a retardation film 13 was produced. Table 1 shows the optical properties of the retardation film.

<Preparation of the first retardation film 14>
Weight average molecular weight synthesized from 4,4′-bis (3,4-dicarboxyphenyl) -2,2-diphenylpropane dianhydride and 2,2′-dichloro-4,4′-diaminobiphenyl ( Mw) 30,000 polyimide was dissolved in cyclopentanone to prepare a 20 wt% polyimide solution. Then, the polyimide solution was applied on the support 4. And as a result of heat-treating this coating film at 130 ° C. for 5 minutes, a transparent and smooth polyimide film having a thickness of 8 μm was formed. In this way, a retardation film 14 was produced. Table 1 shows the optical properties of the retardation film.

<Preparation of the first retardation film 15>
The polyimide used for the retardation film 13 was coated on the support 4 and the coated film was dried at 100 ° C. for 10 minutes. Next, the polyimide coating film and support laminate are biaxially stretched at 160 ° C. by 10% with respect to the length of the laminate before stretching, and a polyimide biaxially stretched film having a thickness of 4 μm is formed on the support. Formed. In this way, a retardation film 135 was produced. Table 1 shows the optical properties of the retardation film.

<Preparation of the first retardation film 16>
Next, a commercially available cellulose acetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) was used as the support, and the first retardation film 13 was used except that the coating film thickness was adjusted. A retardation film 16 was prepared.

<Preparation of lower polarizing plate>
Said 1st phase difference films 1-12 and Fujitac TD80UF were affixed on both surfaces of the polarizing film by the roll to roll using the polyvinyl alcohol-type adhesive agent, and the integrated polarizing plate was produced. As shown in FIG. 2, the lamination angle of each film is 90 degrees when the horizontal direction when the display device is viewed from above is a reference (0 °), as shown in FIG. The angle of the protective film slow axis 102 and 106 was set to 90 °. The produced lower polarizing plate was incorporated into a liquid crystal display device so that the optically anisotropic layer (10 in FIG. 1) was in contact with the upper liquid crystal cell substrate (8 in FIG. 1).

<Preparation of upper polarizing plate>
As the protective film (105 in FIG. 2), a commercially available cellulose acetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd., Re value is 3 nm, Rth value is 50 nm) was used. Further, a polycarbonate film (trade name: Pure Ace WR (Teijin Ltd.) is used as a uniaxial retardation film made of a stretched film between the upper polarizing plate (1 in FIG. 1) and the upper liquid crystal cell substrate (5 in FIG. 1). )) One sheet was disposed, and the slow axis in the plane of the retardation film was configured to coincide with the transmission axis of the upper polarizing plate.
As for the optical properties of the polycarbonate film, Re was 155 nm, Rth was 78 nm, and Re (450) / Re (550) = 0.8. That is, the optical properties required for the second retardation film were satisfied.

<Evaluation of display characteristics of liquid crystal display device>
In the liquid crystal display device produced as described above, the light leakage and the color change from the front during black display in the azimuth direction 45 degrees and the polar angle direction 60 degrees from the front of the apparatus were visually evaluated according to the following criteria. .

(Judgment criteria for light leakage)
A: No light leakage B: Slight light leakage C: Weak light leakage D: Strong light leakage

(Judgment criteria for color change)
A: Does not feel coloring B: Slightly colored C: Colored weakly D: Colored strongly

Table 1 shows the optical characteristics and display characteristics evaluation results of each retardation film.

<Evaluation of brittleness of retardation film>
Five film samples were placed on a 18 cm × 16 cm rubber mat of a Thomson punching machine, punched by measuring the length of the longest crack entering from the four corners, and the brittleness was evaluated by punching suitability. 2 mm or less is indicated by ◯, 2 to 3 mm or less is indicated by Δ, and those exceeding 3 mm are indicated by ×.

From the evaluation results of Table 1, the VA mode liquid crystal display device using the polarizing plate having the retardation film of the present invention, that is, the polarizing plate of the present invention, is light during black display when observed from an oblique direction. Leakage and color change were hardly observed.
On the other hand, since the films 4 to 6 do not satisfy the above formula [3] and / or the above formula [4], in the comparative example using this as the first retardation film, the black film is displayed in the oblique direction. Light leakage and color change were observed. Further, since the film 12 does not satisfy the above formula [4], in the comparative example using this as the first retardation film, light leakage and color change during black display are observed in the oblique direction. It was.

It is the schematic which shows an example of the liquid crystal display device of this invention. It is the schematic which shows an example of the polarizing plate which can be used for this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper polarizing plate 2 Upper polarizing plate absorption axis direction 3 Second retardation film 4 Second retardation film slow axis direction 5 Liquid crystal cell upper electrode substrate 6 Upper substrate alignment control direction 7 Liquid crystal molecule 8 Below liquid crystal cell Electrode substrate 9 Lower substrate orientation control direction 10 First retardation film 14 Lower polarizing plate 15 Lower polarizing plate absorption axis direction 101 Polarizing plate protective film 102 Polarizing plate protective film slow axis direction 103 Polarizing plate polarizing film 104 Direction of polarizing film absorption axis 105 Polarizing plate protective film 106 Polarizing plate protective film slow axis direction

Claims (21)

A retardation film having an optically anisotropic layer of the support及beauty one layer,
The support is made of a cellulose acylate film containing at least one acrylic polymer, the front retardation Re and the thickness direction retardation Rth satisfy the following formula [1], and the wavelength dispersibility thereof is represented by the following formula [ 2]; and the retardation film satisfying the following formula [3] in which the front retardation Re and the retardation Rth in the thickness direction of the retardation film satisfy the following formula [4]:
[1] 0 ≦ Re (630) ≦ 10 and | Rth (630) | ≦ 25
[2] | Re (400) −Re (700) | ≦ 10 and −35 ≦ Rth (400) −Rth (700) ≦ 60
[3] 0 ≦ Re (550) ≦ 10 and 100 ≦ Rth (550) ≦ 300
[4] 1.04 ≦ Rth (450) / Rth (550) ≦ 1.30
In the formula, Re (λ) is represented by Re (λ) = (nx−ny) × d, and represents the front retardation value (unit: nm) at the wavelength λnm, and Rth (λ) is Rth (λ) = It is represented by {(nx + ny) / 2−nz} × d, and represents a retardation value (unit: nm) in the film thickness direction at a wavelength λ nm, where nx is a refractive index in the slow axis direction in the film plane, ny Is the refractive index in the fast axis direction in the film plane, nz is the refractive index in the thickness direction of the film, and d is the thickness (nm) of the film. The retardation film according to claim 1, wherein the wavelength dispersion of the support satisfies the following formula [5]:
[5] | Re (400) −Re (700) | ≦ 10 and 0 ≦ Rth (400) −Rth (700) ≦ 60. The retardation film according to claim 1 or 2, wherein the wavelength dispersion satisfies the following formula [6]:
[6] 1.06 ≦ Rth (450) / Rth (550) ≦ 1.30. The optically anisotropic layer comprises a polymerizable liquid crystal composition containing at least one discotic liquid crystalline compound, the molecules of the discotic liquid crystalline compound are homeotropically aligned, and fixed in a nematic liquid crystal phase by polymerization. The retardation film according to claim 1, which is a formed layer. 2. The optically anisotropic layer is a layer formed by fixing a polymerizable liquid crystal composition containing at least one rod-like liquid crystalline compound in a state of a cholesteric liquid crystal phase with the molecules of the rod-like liquid crystalline compound. The retardation film of any one of -3. The retardation film according to claim 1, wherein the optically anisotropic layer is a polymer layer. The retardation film according to claim 6, wherein the polymer layer contains at least one polymer selected from the group consisting of polyamide, polyimide, polyester, polyetherketone, polyamideimide, and polyesterimide. The retardation film according to claim 1, wherein the optically anisotropic layer contains a fluorine-containing compound. The retardation film according to claim 1, wherein the support comprises a cellulose acylate film containing a cellulose acylate having an acyl substitution degree of 2.70 to 3.00. The retardation film according to claim 1, wherein the acrylic polymer has a weight average molecular weight of 500 or more and less than 10,000. The retardation film according to claim 1, wherein the acrylic polymer is an acrylic polymer having a hydroxyl group in a main chain and / or a side chain. The retardation film according to claim 1, wherein the support is made of a cellulose acylate film containing a plasticizer. The film thickness of the said support body is 10-60 micrometers, The retardation film of any one of Claims 1-12. The polarizing plate which has a polarizing film and the protective film provided in both surfaces of this polarizing film, and at least one of this protective film is a phase difference film of any one of Claims 1-13. Furthermore, it has a second retardation film, the front retardation and the retardation in the thickness direction of the second retardation film satisfy the following formula [7], and the wavelength dispersion of the second retardation film is The polarizing plate of Claim 14 which satisfy | fills following formula [8]:
[7] 70 ≦ Re (550) ≦ 180 and 30 ≦ Rth (550) ≦ 140
[8] 0.7 ≦ Re (450) / Re (550) ≦ 1.0. A liquid crystal display device comprising the retardation film according to any one of claims 1 to 13 and / or the polarizing plate according to claim 14 or 15. Two polarizing plates whose absorption axes are orthogonal to each other, a pair of substrates between the two polarizing plates, and a liquid crystal molecule sandwiched between the pair of substrates, to which no external electric field is applied A liquid crystal display device having a liquid crystal cell having a liquid crystal layer oriented in a direction substantially perpendicular to the pair of substrates in a driving state,
The liquid crystal display device which further contains the phase difference film of any one of Claims 1-13, or the said polarizing plate is a polarizing plate of Claim 14 or 15. The liquid crystal display device further includes a second retardation film, the second retardation film is made of a polymer stretched film, and the front retardation and the retardation in the thickness direction satisfy the following formula [7]. A liquid crystal display device according to claim 16 or 17,
[7] 70 ≦ Re (550) ≦ 180 and 30 ≦ Rth (550) ≦ 140. 19. The liquid crystal display device according to claim 16, further comprising a second retardation film, wherein the wavelength dispersion of the second retardation film satisfies the following formula [8]. Liquid crystal display:
[8] 0.7 ≦ Re (450) / Re (550) ≦ 1.0. The liquid crystal display device further includes a second retardation film, and the second retardation film is a cellulose acylate film, a norbornene film, a polycarbonate film, a polyacrylate film, a polyester film, and a polysulfone film. The liquid crystal display device according to claim 16, comprising any one of films. The liquid crystal display device further includes a second retardation film, and the second retardation film has an in-plane slow axis orthogonal to one of the absorption axes of the two polarizing plates. The liquid crystal display device according to claim 16, wherein the liquid crystal display device is disposed.

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