JP6000916B2 - Liquid crystal display device, retardation film and polarizing plate - Google Patents

Description

  The present invention relates to a liquid crystal display device, a retardation film, and a polarizing plate. More specifically, the present invention relates to a liquid crystal display device in which front luminance and black color shift when viewed from an oblique direction are improved, a retardation film that can be used in the liquid crystal display device, and a polarizing plate having the retardation film.

Flat panel displays such as liquid crystal display devices (hereinafter also referred to as LCDs) have low power consumption and are increasingly used as space-saving image display devices year by year. The liquid crystal display device has a configuration in which, for example, a backlight (hereinafter also referred to as BL), a backlight side polarizing plate, a liquid crystal cell, a viewing side polarizing plate, and the like are provided in this order.
In the recent liquid crystal display device market, developments for power saving, high definition, and color reproducibility improvement are progressing as LCD performance improvement, especially in small size such as tablet PCs and smartphones. Although there is a demand for refinement and improved color reproducibility, the current TV standard (FHD, NTSC (National Television System Committee) ratio 72% ≒ (EBU European Broadcasting Union) ratio 100% ratio) is also in the large size. Development of generation high-definition (4K2K, EBU ratio 100% or more) is in progress.

  From the viewpoint of high definition and improved color reproducibility of liquid crystal display devices, methods for sharpening the emission spectrum of the backlight have been known. In particular, the progress of the three-wavelength light source technology using quantum dots is remarkable, and the color reproduction range is expanded from, for example, 72% to 100% compared with NTSC. For example, Patent Document 1 realizes high brightness and improved color reproducibility by embodying white light using a quantum dot (QD) that emits red light and green light as a phosphor between a blue LED and a light guide plate. How to do is described.

JP 2012-169271 A JP 2012-68611 A JP 2009-244493 A JP 2008-203436 A

However, regarding the fluorescence (PL) application technology shown in Patent Document 1, the quantum dot (Quantum Dot, hereinafter also referred to as QD) is used to realize high luminance and color reproducibility improvement by white light. Further improvement in luminance was required.
Furthermore, when the present inventors examined a liquid crystal display device using the method described in Patent Document 1, the amount of black color shift (black shift) was increased because the color reproduction range was expanded from 72% to 100% of the NTSC ratio. As a result, it has been found that there is a new problem that the color unevenness becomes conspicuous and the black shift is more demanded than ever before. Here, conventionally, as described in Patent Document 2, for example, a sugar ester compound is added to reverse the wavelength dispersion of the retardation Re in the in-plane direction (reverse dispersion refers to the retardation becoming longer as the wavelength becomes longer). There has been proposed a method for improving the black shift of an LCD by using a film adjusted so as to exhibit an increasing optical characteristic. On the other hand, there is also known a method for adjusting the wavelength dispersion of retardation Rth in the film thickness direction instead of in-plane direction retardation Re. Patent Document 3 discloses a J aggregate in which a plurality of dye molecules are assembled. A birefringent film is described. Note that the dye used in Patent Document 3 is usually used as an optical filter that adjusts the transmittance of light having a specific wavelength, as described in Patent Document 4, for example. In particular, there have been few known examples used for the purpose of adjusting retardation other than the example using a special J-aggregate as in Patent Document 3.

Thus, the trade-off is high brightness by improving the BL light utilization rate necessary for power saving, high definition (opening ratio reduction), and color reproducibility improvement (color filter (hereinafter also referred to as CF) transmittance reduction). The relationship is to achieve both improvement in light utilization and color reproducibility, in particular, improvement in front luminance and improvement in black color shift when viewed obliquely.
The problem to be solved by the present invention is to provide a liquid crystal display device in which the front luminance and the black color shift when viewed obliquely are improved.

As a result of intensive studies by the present inventors in order to solve the above-mentioned problems, abnormalities such as dyes exhibiting absorption anisotropy corresponding to the wavelength of the valley of the emission wavelength not used in the light source 3 wavelength and exhibiting anisotropy in absorbance Refraction due to dispersion (anomalous dispersion means that the refractive index of a dye exhibiting such anisotropy of absorbance changes within a range of several tens of nm in the vicinity of the wavelength indicating the maximum absorbance) By using the rate change and controlling the wavelength dependence of the birefringence of the retardation film, it has been found that it is possible to achieve a good black color shift improvement while maintaining high color reproduction unprecedented and can solve the above problems I found.
That is, the said subject is solved by this invention of the following structures.

[1] A retardation film, a liquid crystal cell, and a backlight unit;
The retardation film has a maximum absorbance at 595 ± 10 nm or 655 ± 10 nm, and satisfies the following formulas (1) and (2);
Blue light having a light emission center wavelength in a wavelength band of 430 to 480 nm by the backlight unit;
Green light having an emission center wavelength in a wavelength band of 500 to 600 nm;
Emitting red light having an emission center wavelength in a wavelength band of 600 to 650 nm;
Liquid crystal display device.
Formula (1) 2 ≦ α / α⊥ ≦ 6
(In the formula (1), α represents the maximum absorbance of the retardation film, and α⊥ represents the absorbance with respect to the wavelength at which the absorbance in the direction orthogonal to the direction in which the absorbance of the retardation film is maximized. )
Formula (2) 1.11 ≦ Re (630) / Re (535) ≦ 1.25
(In the formula (2), Re (λ) represents retardation in the in-plane direction of the retardation film (unit: nm) at the wavelength λ nm.)
[2] In the liquid crystal display device according to [1], it is preferable that the half-value width of the blue light, the half-value width of the green light, and the half-value width of the red light are all 100 nm or less.
[3] In the liquid crystal display device according to [1] or [2], the half width of the absorbance peak of the retardation film is preferably 10 to 50 nm.
[4] In the liquid crystal display device according to any one of [1] to [3], the retardation film preferably satisfies the following formula (3).
Formula (3) 0.90 ≦ {Re (535) / Re (450)} / {Re (630) / Re (535)} ≦ 1.1
(In Formula (3), Re (λ) represents retardation (unit: nm) in the in-plane direction of the retardation film at the wavelength λ nm.)
[5] In the liquid crystal display device according to any one of [1] to [4], it is preferable that the direction in which the absorbance of the retardation film is maximum and the slow axis of the retardation film are parallel. .
[6] In the liquid crystal display device according to any one of [1] to [5], the retardation film preferably includes an absorption material having a maximum absorbance at 595 ± 10 nm or 655 ± 10 nm.
[7] In the liquid crystal display device according to [6], the retardation film is preferably a laminate of a base material and an absorbent layer containing an absorbent material, or a single layer of a base material containing an absorbent material.
[8] The liquid crystal display device according to any one of [1] to [7] includes at least one of the liquid crystal cell and the backlight unit, and the liquid crystal cell on the side opposite to the backlight unit. Having a polarizer on one side,
The direction in which the absorbance of the retardation film is maximum is preferably parallel to the absorption axis of the polarizer.
[9] The liquid crystal display device according to any one of [1] to [8] has a viewing side polarizer on a side opposite to the backlight unit with respect to the liquid crystal cell, and the viewing side polarizer and Having at least one retardation film between the liquid crystal cells,
It is preferable that a backlight side polarizer is provided between the liquid crystal cell and the backlight unit, and at least one retardation film is provided between the backlight side polarizer and the liquid crystal cell.
[10] In the liquid crystal display device according to any one of [1] to [9], a backlight unit includes a blue light emitting diode that emits the blue light, and
It is preferable to have a fluorescent material that emits the green light and the red light when the blue light of the blue light emitting diode is incident.
[11] In the liquid crystal display device according to [10], the fluorescent material is a quantum dot member,
It is preferable that the quantum dot member is disposed between the optical sheet member and the blue light source.
[12] Has a maximum absorbance at 595 ± 10 nm,
The following formulas (1) to (3) are satisfied,
A retardation film in which the direction in which the absorbance of the retardation film is maximum is parallel to the slow axis of the retardation film.
Formula (1) 2 ≦ α / α⊥ ≦ 6
(In the formula (1), α represents the maximum absorbance of the retardation film, and α⊥ represents the absorbance with respect to the wavelength at which the absorbance in the direction orthogonal to the direction in which the absorbance of the retardation film is maximized. )
Formula (2) 1.11 ≦ Re (630) / Re (535) ≦ 1.25
Formula (3) 0.90 ≦ {Re (535) / Re (450)} / {Re (630) / Re (535)} ≦ 1.1
(In the formulas (2) and (3), Re (λ) represents the retardation (unit: nm) in the in-plane direction of the retardation film at the wavelength λ nm.)
[13] Has a maximum absorbance at 655 ± 10 nm,
The following formulas (1) to (3) are satisfied,
A retardation film in which the direction in which the absorbance of the retardation film has a maximum value is perpendicular to the slow axis of the retardation film.
Formula (1) 2 ≦ α / α⊥ ≦ 6
(In the formula (1), α represents the maximum absorbance of the retardation film, and α⊥ represents the absorbance with respect to the wavelength at which the absorbance in the direction orthogonal to the direction in which the absorbance of the retardation film is maximized. )
Formula (2) 1.11 ≦ Re (630) / Re (535) ≦ 1.25
Formula (3) 0.90 ≦ {Re (535) / Re (450)} / {Re (630) / Re (535)} ≦ 1.1
(In the formulas (2) and (3), Re (λ) represents the retardation (unit: nm) in the in-plane direction of the retardation film at the wavelength λ nm.)
[14] The retardation film according to [12] or [13] preferably has a half-value width of the absorbance peak of the retardation film of 10 to 50 nm.
[15] In the retardation film according to any one of [12] to [14], the retardation film preferably includes an absorbing material having a maximum absorbance at 595 ± 10 nm or 655 ± 10 nm.
[16] The retardation film according to [15] is preferably such that the retardation film is a laminate of a base material and an absorbent layer containing an absorbent material, or a single layer of a base material containing an absorbent material.
[17] A polarizer;
A polarizing plate having at least one retardation film according to any one of [12] to [16].

  According to the present invention, it is possible to provide a liquid crystal display device in which front luminance and black color shift when viewed from an oblique direction are improved.

FIG. 1 is a schematic view showing a cross section of an example of the liquid crystal display device of the present invention. FIG. 2 is a schematic view showing a cross section of another example of the liquid crystal display device of the present invention.

Hereinafter, the liquid crystal display device, the retardation film, and the polarizing plate will be described in detail.
The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
In the present specification, the “half width” of a peak means the width of the peak at a peak height of 1/2.

[Liquid Crystal Display]
The liquid crystal display device of the present invention has a retardation film, a liquid crystal cell, and a backlight unit; the retardation film has a maximum absorbance at 595 ± 10 nm or 655 ± 10 nm, and the following formula (1) And (2) is satisfied; the backlight unit has a blue light having an emission center wavelength in a wavelength band of 430 to 480 nm, a green light having an emission center wavelength in a wavelength band of 500 to 600 nm, and a wavelength band of 600 to 650 nm. And red light having an emission center wavelength.
Formula (1) 2 ≦ α / α⊥ ≦ 6
(In the formula (1), α represents the maximum absorbance of the retardation film, and α⊥ represents the absorbance with respect to the wavelength at which the absorbance in the direction orthogonal to the direction in which the absorbance of the retardation film is maximized. )
Formula (2) 1.11 ≦ Re (630) / Re (535) ≦ 1.25
(In the formula (2), Re (λ) represents retardation in the in-plane direction of the retardation film (unit: nm) at the wavelength λ nm.)
With such a configuration, the liquid crystal display device of the present invention improves the front luminance and the black color shift when viewed obliquely. The backlight unit emitting the blue light, the green light, and the red light having the emission wavelength center in a specific range has a large value such that the inverse chromatic dispersion satisfies Expression (2). By combining the retardation film having the maximum absorbance at ± 10 nm or 655 ± 10 nm and satisfying the formula (1), the black color shift when viewed from an oblique direction can be improved by the reverse wavelength dispersion characteristic, By using an anomalous dispersion mechanism instead of light absorption, the front luminance can be increased without substantially reducing the light utilization rate from the backlight unit.

<Configuration>
First, the configuration of the liquid crystal display device of the present invention will be described with reference to the drawings. However, the configuration of the present invention is not limited by the drawings.
1 and 2 schematically show an example of the liquid crystal display device of the present invention.
The liquid crystal display device 41 of the present invention shown in FIGS. 1 and 2 includes a retardation film F3 or F4, a liquid crystal cell 11, and a backlight unit 31. Furthermore, the liquid crystal display device 41 of the present invention preferably includes the backlight side polarizer 22 and the display side polarizing plate 1, and has the viewing side polarizer 2 on the side opposite to the backlight unit 31 with respect to the liquid crystal cell 11. Preferably, at least one retardation film F2 is provided between the viewing side polarizer 2 and the liquid crystal cell 11, and the backlight side polarizer 22 is provided between the liquid crystal cell 11 and the backlight unit 31. It is preferable to have at least one retardation film F3 between the backlight side polarizer 22 and the liquid crystal cell 11. However, the retardation film may be used as an outer side polarizing plate protective film for the viewing side polarizing plate or an outer side polarizing plate protective film for the backlight side polarizing plate.
The liquid crystal display device 41 of the present invention preferably has a polarizing plate protective film (outer side polarizing plate protective film of the visual side polarizing plate) F1 on the opposite side of the viewing side polarizer 2 from the retardation film F2. The liquid crystal display device 41 of the present invention preferably has a polarizing plate protective film (outer side polarizing plate protective film of the backlight side polarizing plate) F4 on the opposite side of the retardation film F3 of the backlight side polarizer 22.
The retardation film described above is preferably a laminate of a base material and an absorbent layer containing the absorbent material, or a single layer of the base material containing the absorbent material. For example, the retardation film F2 is a laminate of the base material 4 and the absorbent layer 3 containing the absorbent material as shown in FIG. 2, or a single layer of the base material 4 containing the absorbent material as shown in FIG. Is preferred. Similarly, the retardation film F3 is a laminate of the base material 24 and the absorbent layer 23 containing the absorbent material as shown in FIG. 2, or a single layer of the base material 24 containing the absorbent material as shown in FIG. It is preferable.

The liquid crystal display device of the present invention has a polarizer between the liquid crystal cell and the backlight unit and on at least one side of the liquid crystal cell opposite to the backlight unit, and the retardation film has a maximum absorbance. It is preferable that the value direction is parallel to the absorption axis of the polarizer from the viewpoint of further suppressing the reduction in front luminance.
For example, the liquid crystal display device 41 of the present invention shown in FIGS. 1 and 2 includes a backlight side polarizer 22 between the liquid crystal cell 11 and the backlight unit 31, and the backlight unit 31 with respect to the liquid crystal cell 11. Has a viewing side polarizer 2 on the opposite side. In the liquid crystal display device 41 of the present invention shown in FIGS. 1 and 2, the direction in which the absorbance of the retardation film F2 is maximum is parallel to the absorption axis of the backlight side polarizer 22 or the viewing side polarizer 2, and The direction in which the absorbance of the retardation film F3 is maximum is preferably parallel to the absorption axis of the backlight side polarizer 22 or the viewing side polarizer 2.

<Retardation film and retardation film of the present invention>
In the liquid crystal display device of the present invention, the above-mentioned retardation film has a maximum absorbance at 595 ± 10 nm or 655 ± 10 nm, and satisfies the following formulas (1) and (2).
Formula (1) 2 ≦ α / α⊥ ≦ 6
(In the formula (1), α represents the maximum absorbance of the retardation film, and α⊥ represents the absorbance with respect to the wavelength at which the absorbance in the direction orthogonal to the direction in which the absorbance of the retardation film is maximized. )
Formula (2) 1.11 ≦ Re (630) / Re (535) ≦ 1.25
(In the formula (2), Re (λ) represents retardation in the in-plane direction of the retardation film (unit: nm) at the wavelength λ nm.)

(optical properties)
In the present invention, among the above-mentioned retardation films, it is particularly preferable to use the following novel retardation film of the present invention.
In the conventional reverse dispersion film, the slopes of the chromatic dispersion on the short wavelength side and the long wavelength side are different, and greatly deviated from linear chromatic dispersion over the ideal short wavelength to long wavelength, whereas the retardation of the present invention When a film is used, the slopes of chromatic dispersion on the short wavelength side and the long wavelength side can be matched, and optical compensation close to ideal can be realized over a short wavelength to a long wavelength. The black color shift is greatly improved.
The retardation film of the present invention is specifically the following first and second aspects.

The first aspect of the retardation film of the present invention has a maximum absorbance at 595 ± 10 nm, satisfies the following formulas (1) to (3), and the direction and retardation in which the absorbance of the retardation film is the maximum. It is a retardation film in which the slow axis of the film is parallel.
Formula (1) 2 ≦ α / α⊥ ≦ 6
(In the formula (1), α represents the maximum absorbance of the retardation film, and α⊥ represents the absorbance with respect to the wavelength at which the absorbance in the direction orthogonal to the direction in which the absorbance of the retardation film is maximized. )
Formula (2) 1.11 ≦ Re (630) / Re (535) ≦ 1.25
Formula (3) 0.90 ≦ {Re (535) / Re (450)} / {Re (630) / Re (535)} ≦ 1.1
(In the formulas (2) and (3), Re (λ) represents the retardation (unit: nm) in the in-plane direction of the retardation film at the wavelength λ nm.)
The first aspect of the retardation film of the present invention in which the direction in which the absorbance is maximum (so-called absorption anisotropy axis) is parallel to the slow axis of the retardation film is as follows. Refractive index ns in the slow axis direction (direction parallel to the stretching direction) of the retardation film due to anomalous dispersion of a dye or the like having a maximum absorbance at 595 ± 10 nm which is a band between them and exhibiting anisotropy of absorbance By reducing the short wavelength side of the wavelength that is the maximum value of absorbance only and raising the long wavelength side slightly, Δn (Δn = ns−nf; nf represents the refractive index in the fast axis direction of the retardation film) ) In the vicinity of 535 nm can be lowered and the long wavelength side in the vicinity of 630 nm can be increased, and the slope of Re (630) / Re (535), which is the chromatic dispersion on the long wavelength side, can be increased to reduce the chromatic dispersion. Linear (Short wavelength wave Dispersing a is Re (535) / Re (450) and the same degree of inclination), namely can achieve the phase difference film is a reverse wavelength dispersion satisfying the above expression (3), it is possible to further improve the black color shift.

The second aspect of the retardation film of the present invention has a maximum absorbance at 655 ± 10 nm, satisfies the following formulas (1) to (3), and the direction and retardation in which the absorbance of the retardation film is the maximum. It is a retardation film in which the slow axes of the films are orthogonal.
Formula (1) 2 ≦ α / α⊥ ≦ 6
(In the formula (1), α represents the maximum absorbance of the retardation film, and α⊥ represents the absorbance with respect to the wavelength at which the absorbance in the direction orthogonal to the direction in which the absorbance of the retardation film is maximized. )
Formula (2) 1.11 ≦ Re (630) / Re (535) ≦ 1.25
Formula (3) 0.90 ≦ {Re (535) / Re (450)} / {Re (630) / Re (535)} ≦ 1.1
(In the formulas (2) and (3), Re (λ) represents the retardation (unit: nm) in the in-plane direction of the retardation film at the wavelength λ nm.)
The first aspect of the retardation film of the present invention in which the direction in which the absorbance is maximum (so-called absorption anisotropy axis) is orthogonal to the slow axis of the retardation film is a long wavelength exceeding red light. Only for the refractive index nf in the fast axis direction (direction perpendicular to the stretching direction) of the retardation film due to anomalous dispersion such as a dye having a maximum absorbance in the band of 655 ± 10 nm and exhibiting anisotropy of absorbance. Raise the short wavelength side of 630 nm (and lower the long wavelength side) of Δn (Δn = ns−nf) by slightly raising the short wavelength side of the wavelength that is the maximum absorbance and lowering the long wavelength side slightly. The slope of Re (630) / Re (535), which is chromatic dispersion on the long wavelength side, is increased, and the chromatic dispersion is linear (Re (535) / Re (450), which is chromatic dispersion on the short wavelength side). The same slope) KazuSatoshi the formula (3) can be achieved retardation film is a reverse wavelength dispersion satisfying, it is possible to further improve the black color shift.

The first aspect of the above-described retardation film and the retardation film of the present invention preferably has a maximum absorbance at 595 ± 10 nm, preferably has a maximum absorbance at 595 ± 5 nm, and has an absorbance at 595 ± 3 nm. More preferably, it has a maximum value.
The second aspect of the above-described retardation film and the retardation film of the present invention preferably has a maximum absorbance at 655 ± 10 nm, preferably has a maximum absorbance at 655 ± 5 nm, and has an absorbance at 655 ± 3 nm. More preferably, it has a maximum value.

The above-mentioned retardation film and the retardation film of the present invention satisfy the following formula (1).
Formula (1) 2 ≦ α / α⊥ ≦ 6
(In the formula (1), α represents the maximum absorbance of the retardation film, and α⊥ represents the absorbance with respect to the wavelength at which the absorbance in the direction orthogonal to the direction in which the absorbance of the retardation film is maximized. )
When α / α⊥ is 2 or more, it is possible to improve the black color shift when viewed obliquely than when it is less than 2. When α / α⊥ is 6 or less, it is possible to improve the black color shift when viewed obliquely as compared to when 6 is exceeded.
α / α⊥ is preferably 2.5 to 5.5, more preferably 3 to 5, and particularly preferably 3.5 to 4.5.

The above-mentioned retardation film and the retardation film of the present invention satisfy the following formula (2).
Formula (2) 1.11 ≦ Re (630) / Re (535) ≦ 1.25
(In formula (2), Re (λ) represents retardation in the in-plane direction of retardation film at wavelength λ nm (unit: nm).)
When Re (630) / Re (535) is 1.11 or more, it is possible to improve the black color shift when viewed obliquely as compared to when it is less than 1.11. When Re (630) / Re (535) is 1.25 or less, it is possible to improve the black color shift when viewed obliquely as compared to when exceeding 1.25.
Re (630) / Re (535) is preferably 1.14 to 1.22, and more preferably 1.16 to 1.20.

The retardation film described above preferably satisfies the following formula (3) from the viewpoint of improving the black color shift when viewed from an oblique direction by matching the inclinations of chromatic dispersion on the short wavelength side and the long wavelength side.
Formula (3) 0.90 ≦ {Re (535) / Re (450)} / {Re (630) / Re (535)} ≦ 1.1
(In Formula (3), Re (λ) represents retardation (unit: nm) in the in-plane direction of the retardation film at the wavelength λ nm.)
Re (630) / Re (535) is preferably 0.95 to 1.05, and more preferably 0.98 to 1.02.

  In the present invention, it is preferable that the direction in which the absorbance of the retardation film has a maximum value is parallel to the slow axis of the retardation film, that is, the first aspect of the retardation film of the present invention. Is more preferable than the second embodiment of the retardation film of the present invention.

The retardation film described above preferably has Re (535) of 20 to 90 nm, more preferably 30 to 80 nm, and particularly preferably 40 to 70 nm.
The retardation film described above preferably has a retardation Rth (535) in the film thickness direction of 80 to 170 nm, more preferably 90 to 160 nm, and particularly preferably 100 to 150 nm.

In this specification, Re, Rth, and Nz at a wavelength λnm can be measured as follows.
Re is measured with KOBRA 21ADH (manufactured by Oji Scientific Instruments Co., Ltd.) by making light of wavelength λ nm incident in the normal direction of the film.
Rth is measured by making light of wavelength λ nm incident from the direction inclined + 40 ° with respect to the film normal direction with the above-mentioned Re and in-plane slow axis (determined by KOBRA 21ADH) as the tilt axis (rotation axis). The retardation value measured and the retardation value measured by making light of wavelength λ nm incident from a direction inclined by −40 ° with respect to the film normal direction with the in-plane slow axis as the tilt axis (rotation axis) 3 in total Based on retardation values measured in two directions, KOBRA 21ADH is used for calculation. Here, as the assumed value of the average refractive index, values in the thermoplastic 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 main optical films are exemplified below: cellulose acylate (1.48), cycloolefin thermoplasticity (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49) Polystyrene (1.59).

  In this specification, an angle (for example, an angle such as “90 °”) and a relationship (for example, “orthogonal”, “parallel”, “intersection at 45 °”, etc.) are allowable in the technical field to which the present invention belongs. The range of errors to be included. For example, it means that the angle is within the range of strict angle ± 10 °, and the error from the strict angle is preferably 5 ° or less, and more preferably 3 ° or less.

In the present specification, the “slow axis” of a retardation film or the like means a direction in which the refractive index is maximized. The “fast axis” of a retardation film or the like means a direction orthogonal to the direction in which the refractive index is maximum.
Further, in this specification, numerical values, numerical ranges, and qualitative expressions (for example, “equivalent”, “equal”, etc.) indicating optical characteristics of each member such as a retardation region, a retardation film, and a liquid crystal layer are used. ) Is interpreted to indicate numerical values, numerical ranges and properties including generally allowable errors for liquid crystal display devices and members used therefor.
In this specification, “front” means a normal direction relative to the display surface, and “front luminance” means white luminance measured in the normal direction of the display surface.

(Absorbing material)
In the present invention, it is preferable that the above-mentioned retardation film has an absorbing material having a maximum absorbance at 595 ± 10 nm or 655 ± 10 nm.
In the present invention, the retardation film is preferably a laminate of a base material and an absorbent layer containing an absorbent material, or a single layer of a base material containing an absorbent material. A layer is more preferable from the viewpoint of manufacturing simplicity.
As a specific embodiment of the absorbing material, the absorbing material may be kneaded into the base material constituting the retardation film, and an “absorbing layer” containing the absorbing material separately from the base material constituting the retardation film. It may be provided.

  The absorption layer may consist of one layer or two or more layers. One of the layers constituting the absorbent layer may be a layer containing two or more kinds of absorbent materials, and each of the plurality of layers constituting the absorbent layer may contain one kind of absorbent material.

  The absorbing material is preferably a dye or a pigment, more preferably a dye.

  As the absorbing material having a maximum absorbance at 595 ± 10 nm, cyanine-based, squarylium-based, azomethine-based, xanthene-based, oxonol-based or azo-based compounds are preferable, and cyanine-based and oxonol-based dyes are more preferably used. An example of an absorbing material having a maximum absorbance at 595 ± 10 nm is shown below.

  For the synthesis of cyanine dyes, reference can be made to the descriptions in JP-A-7-230671, European Patent 0778493 and US Pat. No. 5,459,265. Regarding the synthesis of azo dyes, reference can be made to the specifications of British Patent Nos. 539703, 575691 and US Pat. No. 2,956,879, as well as Hiroshi Horiguchi's review and review of synthetic dyes (Sankyo Publishing, published in 1968). For the synthesis of azomethine dyes, reference can be made to the descriptions in JP-A Nos. 62-3250, 4-178646, and 5-323501. Oxonol dyes can be synthesized with reference to the descriptions in JP-A-7-230671, European Patent 0778493 and US Pat. No. 5,459,265. For the synthesis of merocyanine dyes, reference can be made to the descriptions in US Pat. No. 2,170,806 and JP-A Nos. 55-155350 and 55-161232. Regarding the synthesis of anthraquinone dyes, descriptions of British Patent No. 710060, US Pat. No. 3,575,704, JP-A-48-5425 and Hiroshi Horiguchi, Review / Synthetic dyes (Sankyo Publishing, issued in 1968) You can refer to it. For other dyes, FM Harmer, “Heterocyclic Compounds-Cyanine Compounds and Related Compounds”, John Willie and John H. Harmer, “Heterocyclic Compounds-Cyanine Compounds and Related Compounds”. • John Wiley and Sons, New York, London, 1964; “D. M. Sturmer” “Heterocyclic Compounds—Heterocyclic Compounds” -Special Topics in Heterocyclic Chemistry) Chapter 8, Section 14, 482-515, John Wiley and Sons, New York, London, 1977; “Rod's Chemistry of Carbon Compounds”. 2nd Edition, Volume 4, Part B, Chapter 15, pages 369-422, Elsevier Science Publishing Company Inc., New York, 1977; JP-A-5-88293 and It can be synthesized with reference to the descriptions in each publication of JP-A-6-3139939.

As the dye, two or more kinds of pigments as described above can be used in combination. For example, when the dye is in an aggregated state, the wavelength generally shifts to the longer wavelength side, and the peak becomes sharp. For this reason, some dyes having an absorption maximum in the wavelength range of 480 to 520 nm include those whose aggregates have an absorption maximum in the range of 595 ± 10 nm.
As the dye having the maximum absorption in the wavelength band of 480 to 520 nm, squarylium, azomethine, cyanine, oxonol, anthraquinone, azo or benzylidene compounds are preferably used. As the azo dye, many azo dyes described in GB539703, 575691, US29556879 and Hiroshi Horiguchi's “Review Synthetic Dye” Sankyo Publishing, etc. can be used. Specific examples include the compounds described in JP-A-2008-203436, [0018] to [0020].
When such a dye is used in a state where an aggregate is partially formed, an absorption maximum can be obtained in both the wavelength range of 480 to 520 m and the wavelength range of 595 ± 10 nm. Examples of such dyes are shown below.

  The associated dye forms a so-called J band and shows a sharp absorption spectrum peak. The association of dyes and the J band are described in various literatures (for example, Photographic Science and engineering Vol. 18, No. 323-335 (1974)). The absorption maximum of the dye in the J-association state moves to the longer wave side than the absorption maximum of the dye in the solution state. Therefore, whether the dye contained in the absorption layer is in an associated state or a non-associated state can be easily determined by measuring the absorption maximum. In an associated dye, the movement of the absorption maximum is preferably 30 nm or more, more preferably 40 nm or more, and most preferably 45 nm or more.

  The dye used in the association state is preferably a methine dye, and most preferably a cyanine dye or an oxonol dye. These dyes include compounds that form aggregates only by dissolving in water, but in general, gelatin or a salt (eg, barium chloride, calcium chloride, sodium chloride) is added to an aqueous dye solution to form an aggregate. Can be formed. As a method for forming the aggregate, a method of adding gelatin to an aqueous dye solution is particularly preferable. A plurality of dyes having different absorption maximums can be dispersed in an aqueous solution to which gelatin is added, and then mixed to prepare a sample containing a plurality of aggregates having different absorption maximums. Depending on the dye, each aggregate can be formed simply by dispersing a plurality of dyes in an aqueous solution containing gelatin. The dye aggregate can also be formed as a solid fine particle dispersion of the dye. In order to obtain a solid fine particle dispersion, a known disperser can be used. Examples of the disperser include a ball mill, a vibrating ball mill, a planetary ball mill, a sand mill, a colloid mill, a jet mill, and a roller mill. The disperser is described in JP-A-52-92716 and WO88 / 074794. A vertical or horizontal medium disperser is preferred.

Examples of the absorbing material having the maximum absorbance at 655 ± 10 nm include the dye compounds described in Journal of Information Recording Materials, (1988), 16 (1), 23-31. Are incorporated into the present invention.
Specific examples of the absorbing material having the maximum absorbance at 655 ± 10 nm include the following compounds.

  Examples of other absorbing materials include dye compounds described in JP-A No. 2000-32419, JP-A No. 2002-122729, and JP-P 45044496. The contents of these publications are incorporated in the present invention. It is.

  The content of the dye in the absorbing layer is preferably 0.001 to 0.050% by mass, more preferably 0.001 to 0.030% by mass with respect to the total mass of the absorbing layer. It is especially preferable that it is 010-0.030 mass%.

  The absorption spectrum of the absorbing material having a maximum absorbance at 595 ± 10 nm or 655 ± 10 nm is sharp to selectively cut the light so as not to affect the blue light, green light and red light. Specifically, it is preferable that the half width of the absorption spectrum of the absorption material having the maximum absorbance at 595 ± 10 nm (the width of the wavelength region showing the absorbance at half the absorbance at the absorption maximum) is 5 to 50 nm, More preferably, it is 10-50 nm. The half width of the absorption spectrum of the absorbing material having the maximum absorbance at 655 ± 10 nm is preferably 5 to 50 nm, and more preferably 10 to 50 nm.

As a means for setting the full width at half maximum in such a range, a plurality of dyes or pigments having different absorption maxima in one wavelength region are contained in the layer containing the absorbing material, or an aggregate of dyes is contained in the layer containing the absorbing material. The means of making it etc. are mentioned.
Specifically, methine dyes (for example, cyanine, merocyanine, oxonol, pyromethene, styryl, arylidene), diphenylmethane dye, triphenylmethane dye, xanthene dye, squarylium dye, croconium dye, azine dye, acridine dye, thiazine dye And oxazine dyes can be selected. These dyes are preferably used in aggregates.

  In addition, an additive such as an infrared absorber or an ultraviolet absorber may be added to the absorption layer, and those described in JP-A-2008-203436, [0031] can be used.

  When the retardation film is a laminate of an absorbent layer containing a base material and an absorbent material, the absorbent layer preferably contains a polymer binder, as described in JP-A-2008-203436, [0032] to [0034]. Can be used. In the case of a laminate of an absorbent layer containing a base material and an absorbent material, an undercoat layer can be provided on the support when the absorbent layer is provided on a support such as an arbitrary base material. As the undercoat layer, those described in [0039] of JP-A-2008-203436 can be used. In the case of a laminate of an absorbent layer containing a base material and an absorbent material, the absorbent layer can be formed by the method described in [0040] of JP-A-2008-203436.

(Base material)
Whether the retardation film is a laminate of an absorbent layer containing a base material and an absorbent material or a single layer of a base material containing an absorbent material that is a single layer of a base material containing an absorbent material, There is no particular limitation except that the conditions of the retardation film used in the liquid crystal display device of the present invention are satisfied, and a known substrate can be used.

  As the base material, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is used. Specific examples of such thermoplastic resins include cellulose ester resins, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins, cyclic polyolefin resins ( Norbornene resin), polyarylate resin, polystyrene resin, polyvinyl alcohol resin, and mixtures thereof. Among them, the base material of the surface film F1 is preferably a cyclic polyolefin resin, a cellulose resin, or a polyester resin, more preferably a cyclic polyester resin, a cellulose acylate resin, or polyethylene terephthalate, and particularly preferably a cellulose acylate resin.

  The cellulose ester resin is an ester of cellulose and a fatty acid. Specific examples of the cellulose ester resin include triacetyl cellulose, diacetyl cellulose, tripropyl cellulose, dipropyl cellulose, and the like. A preferred embodiment of the cellulose ester resin used for the retardation film is the same as the preferred embodiment of the cellulose acylate having an acyl substitution degree of 2.0 to 2.6 described in JP2012-066861A. The contents are incorporated into the present invention.

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

  Various products are commercially available as the cyclic polyolefin resin. Specific examples include the product names “ZEONEX” and “ZEONOR” manufactured by ZEON CORPORATION, the product name “ARTON” manufactured by JSR Corporation, the product name “TOPAS” manufactured by TICONA, and the product rules manufactured by Mitsui Chemicals, Inc. “APEL” may be mentioned.

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

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

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

  In the measurement of Re and Rth of the retardation film, when the thermoplastic resin used for the base material of the retardation film is a cellulose ester, the retardation of the retardation film on the viewing side polarizing plate is 1.48 as the average refractive index. Measure.

The above Re and Rth are the types of thermoplastic resins used in the above-mentioned retardation film (if the thermoplastic resin used in the retardation film is a cellulose ester, for example, the degree of substitution of the cellulose ester), added with the thermoplastic resin It can be adjusted by the amount of the agent, the addition of the retardation developer, the film thickness, the stretching direction and stretching ratio of the film.
Preferred embodiments of the additive used for the retardation film include a sugar ester compound described in JP 2012-068661 A, an additive having a negative intrinsic birefringence, a nitrogen-containing aromatic compound plasticizer, fine particles, and expression of retardation. This is the same as the preferred embodiment of the agent, and the contents of this publication are incorporated in the present invention.
A preferred embodiment of the method for producing a retardation film is the same as the preferred embodiment of the method for producing a cellulose acylate film described in JP 2012-068661 A, and the contents of this publication are incorporated in the present invention.

  The thickness of the retardation film and the protective film described later can be appropriately set, but is generally about 1 to 500 μm from the viewpoints of workability such as strength and handling, and thin layer properties. 1-300 micrometers is especially preferable, and 5-200 micrometers is more preferable. A retardation film and a protective film described later are particularly suitable when the thickness is 5 to 150 μm.

<Polarizing plate>
Next, the polarizing plate will be described.
The polarizing plate of the present invention has a polarizer and at least one retardation film of the present invention.
The polarizing plate of the present invention usually has a polarizer and two polarizing plate protective films (hereinafter also referred to as protective films) disposed on both sides of the polarizing plate, similarly to the polarizing plate used in a liquid crystal display device. Among these protective films, it is preferable that the retardation film of the present invention is used as a protective film having at least one retardation film of the present invention and disposed on the liquid crystal cell side.
However, when the polarizing plate of the present invention is used as the backlight-side polarizing plate of the liquid crystal display device of the present invention, a polarizing plate protective film may be included on the surface of the polarizer on the backlight unit side. It does not have to be.

(Polarizer)
As the polarizer, it is preferable to use a polymer film in which iodine is adsorbed and oriented. The polymer film is not particularly limited, and various types can be used. For example, polyvinyl alcohol films, polyethylene terephthalate films, ethylene / vinyl acetate copolymer films, partially saponified films of these, hydrophilic polymer films such as cellulose films, polyvinyl alcohol dehydrated products and polychlorinated Examples include polyene-based oriented films such as vinyl dehydrochlorinated products. Among these, it is preferable to use a polyvinyl alcohol film excellent in dyeability with iodine as a polarizer.

  Polyvinyl alcohol or a derivative thereof is used as the material for the polyvinyl alcohol film. Derivatives of polyvinyl alcohol include polyvinyl formal, polyvinyl acetal and the like, olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid and crotonic acid, alkyl esters thereof, acrylamide and the like. can give.

  The degree of polymerization of the polymer film material is generally 500 to 10,000, preferably in the range of 1000 to 6000, and more preferably in the range of 1400 to 4000. Furthermore, in the case of a saponified film, the saponification degree is preferably 75 mol% or more, more preferably 98 mol% or more, for example, from the viewpoint of solubility in water, and 98.3 to 99.8 mol. % Is more preferable.

  The polymer film (unstretched film) is subjected to at least uniaxial stretching treatment and iodine dyeing treatment according to a conventional method. Furthermore, boric acid treatment and washing treatment can be performed. In addition, the polymer film (stretched film) subjected to the treatment is dried according to a conventional method to become a polarizer.

  The stretching method in the uniaxial stretching treatment is not particularly limited, and either a wet stretching method or a dry stretching method can be employed. Examples of the stretching means of the dry stretching method include an inter-roll stretching method, a heated roll stretching method, and a compression stretching method. Stretching can also be performed in multiple stages. In the stretching means, the unstretched film is usually heated. The stretch ratio of the stretched film can be appropriately set according to the purpose, but the stretch ratio (total stretch ratio) is about 2 to 8 times, preferably 3 to 7 times, more preferably 3.5 to 6.5 times. Is desirable.

  The iodine dyeing treatment is performed, for example, by immersing the polymer film in an iodine solution containing iodine and potassium iodide. The iodine solution is usually an iodine aqueous solution, and contains iodine and potassium iodide as a dissolution aid. The iodine concentration is about 0.01 to 1% by mass, preferably 0.02 to 0.5% by mass, the potassium iodide concentration is about 0.01 to 10% by mass, and further 0.02 to 8% by mass. It is preferable to use it.

  In the iodine dyeing treatment, the temperature of the iodine solution is usually about 20 to 50 ° C, preferably 25 to 40 ° C. The immersion time is usually about 10 to 300 seconds, preferably 20 to 240 seconds. In the iodine dyeing treatment, the iodine content and potassium content in the polymer film are adjusted to be in the above ranges by adjusting conditions such as the concentration of the iodine solution, the immersion temperature of the polymer film in the iodine solution, and the immersion time. . The iodine dyeing process may be performed at any stage before the uniaxial stretching process, during the uniaxial stretching process, or after the uniaxial stretching process.

  In consideration of optical characteristics, the iodine content of the polarizer is, for example, in the range of 2 to 5% by mass, and preferably in the range of 2 to 4% by mass.

  The polarizer preferably contains potassium. The potassium content is preferably in the range of 0.2 to 0.9 mass%, more preferably in the range of 0.5 to 0.8 mass%. When the polarizer contains potassium, a polarizing film having a preferable composite elastic modulus (Er) and a high degree of polarization can be obtained. The potassium can be contained, for example, by immersing a polymer film, which is a material for forming a polarizer, in a solution containing potassium. The solution may also serve as a solution containing iodine.

  As the drying treatment step, a conventionally known drying method such as natural drying, blow drying, or heat drying can be used. For example, in heat drying, the heating temperature is about 20 to 80 ° C., and the drying time is about 1 to 10 minutes. Moreover, it can extend | stretch suitably also in this drying process process.

  It does not specifically limit as thickness of a polarizer, Usually, it is 5-300 micrometers, Preferably it is 10-200 micrometers, More preferably, it is 20-100 micrometers.

  As optical properties of the polarizer, the single transmittance when measured with a single polarizer is preferably 43% or more, and more preferably in the range of 43.3 to 45.0%. In addition, it is preferable that the orthogonal transmittance measured by superposing two polarizers so that the absorption axes of the two polarizers are 90 ° with each other is smaller, and practically 0.00% The content is preferably 0.050% or less and more preferably 0.030% or less. The degree of polarization is preferably 99.90% or more and 100% or less for practical use, and particularly preferably 99.93% or more and 100% or less. Even when measured as a polarizing plate, it is preferable to obtain optical characteristics substantially equivalent to this.

(Polarizing plate protective film)
The polarizing plate of the present invention may or may not have a polarizing plate protective film on the side opposite to the liquid crystal cell of the polarizer.
As the protective film disposed on the side opposite to the liquid crystal cell, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is used. Specific examples of such a thermoplastic resin include the thermoplastic resins mentioned as the base material of the retardation film. Among these, a cellulose resin is preferable, and triacetyl cellulose is particularly preferable. Many products of triacetylcellulose are commercially available, which is advantageous in terms of availability and cost. Examples of commercially available products of triacetyl cellulose include trade names “UV-50”, “UV-80”, “SH-80”, “TD-80U”, “TD-TAC”, and “UZ” manufactured by Fujifilm Corporation. -TAC "," TD60UL "and" KC series "manufactured by Konica.

(Adhesive layer)
Adhesives, pressure-sensitive adhesives, and the like can be appropriately employed for laminating the polarizer and the retardation film or protective film depending on the polarizer and the retardation film or protective film. The adhesive and the adhesion treatment method are not particularly limited. For example, an adhesive made of a vinyl polymer, or at least a vinyl alcohol polymer such as boric acid, borax, glutaraldehyde, melamine, or oxalic acid. It can be carried out via an adhesive comprising a water-soluble crosslinking agent. The adhesive layer made of such an adhesive can be formed as an aqueous solution coating / drying layer, etc. In preparing the aqueous solution, a crosslinking agent, other additives, and a catalyst such as an acid are also blended as necessary. be able to. In particular, when a polyvinyl alcohol polymer film is used as the polarizer, it is preferable from the viewpoint of adhesiveness to use an adhesive containing a polyvinyl alcohol resin. Furthermore, an adhesive containing a polyvinyl alcohol-based resin having an acetoacetyl group is more preferable from the viewpoint of improving durability.

  The polyvinyl alcohol-based resin is not particularly limited, but an average degree of polymerization of about 100 to 3000 and an average degree of saponification of about 85 to 100 mol% are preferable from the viewpoint of adhesiveness. Moreover, it is although it does not specifically limit as a density | concentration of adhesive agent aqueous solution, It is preferable that it is 0.1-15 mass%, and it is more preferable that it is 0.5-10 mass%. The thickness of the adhesive layer is preferably about 30 to 1000 nm, and more preferably 50 to 300 nm in the thickness after drying. If this thickness is too thin, the adhesive strength is insufficient, and if it is too thick, the probability of appearance problems increases.

  As other adhesives, thermosetting resins or ultraviolet curable resins such as (meth) acrylic, urethane-based, acrylurethane-based, epoxy-based, and silicone-based resins can be used.

<Backlight unit>
In the liquid crystal display device of the present invention, the backlight unit has blue light having an emission center wavelength in a wavelength band of 430 to 480 nm, green light having an emission center wavelength in a wavelength band of 500 to 600 nm, and a wavelength band of 600 to 650 nm. And red light having an emission center wavelength.
The wavelength band of the blue light emitted from the backlight unit is preferably 450 to 480 nm, and more preferably 460 to 470 nm.
The wavelength band of the green light emitted from the backlight unit is preferably 520 to 550 nm, and more preferably 530 to 540 nm.
The wavelength band of the red light emitted from the backlight unit is preferably 610 to 650 nm, and more preferably 620 to 640 nm.

  The configuration of the backlight unit may be an edge light method using a light guide plate, a reflection plate, or the like as a constituent member, or may be a direct type. It is preferable to provide. There is no restriction | limiting in particular as such a reflecting member, A well-known thing can be used, and it is described in patent 3416302, patent 3363565, patent 4091978, patent 3448626, etc., The content of these gazettes is this Incorporated into the invention.

In the liquid crystal display device of the present invention, the full width at half maximum of each emission intensity of the blue light, green light and red light emitted from the backlight unit is preferably 100 nm or less, and more preferably 50 nm or less. , 45 nm or less is particularly preferable, and 40 nm or less is more particularly preferable. Among these, it is even more particularly preferable that the full width at half maximum of each emission intensity of the blue light is 30 nm or less.
In the present invention, the light source of the backlight unit is a blue light emitting diode that emits the blue light, and the blue light of the blue light emitting diode is incident. An aspect having a fluorescent material that emits the green light and the red light, or the backlight unit emits the blue laser that emits the blue light, the green laser that emits the green light, and the red light. And a red laser.
As a light source of the backlight unit, a blue light emitting diode that emits blue light, a green light emitting diode that emits green light, and a red light emitting diode that emits red light may be used.
Further, the backlight unit includes an ultraviolet light emitting diode that emits ultraviolet light, and a quantum dot member that emits the blue light, the green light, and the red light when the ultraviolet light of the ultraviolet light emitting diode is incident. It may be used.

Examples of fluorescent materials include yttrium / aluminum / garnet yellow phosphors and terbium / aluminum / garnet yellow phosphors. The fluorescence wavelength of the fluorescent material can be controlled by changing the particle diameter of the phosphor.
In the liquid crystal image display device of the present invention, a blue light emitting diode that emits the blue light, and a fluorescent material that emits the green light and the red light when the blue light of the blue light emitting diode enters the quantum dot member ( For example, a quantum dot sheet or a bar-shaped quantum dot bar), and the quantum dot member is preferably disposed between the optical sheet member and the blue light source. There is no restriction | limiting in particular as such a quantum dot member, Although a well-known thing can be used, For example, Unexamined-Japanese-Patent No. 2012-169271, SID'12 DIGEST p. 895, etc., and the contents of these documents are incorporated in the present invention. As such a quantum dot sheet, QDEF (Quantum Dot Enhancement Film, manufactured by Nanosys) can be used.

In the liquid crystal display device of the present invention, it is preferable that the backlight unit has a blue wavelength selection filter that selectively transmits light having a wavelength shorter than 460 nm among the blue light.
In the liquid crystal display device of the present invention, it is preferable that the backlight unit includes a red wavelength selection filter that selectively transmits light having a wavelength longer than 630 nm among the red light.
Such a blue wavelength selection filter and a red wavelength selection filter are not particularly limited, and known ones can be used, and are described in JP-A-2008-52067. Incorporated into the invention.

  In addition, the backlight unit preferably includes a known diffusion plate, diffusion sheet, prism sheet (for example, BEF), and a light guide. Other members are also described in Japanese Patent No. 3416302, Japanese Patent No. 3363565, Japanese Patent No. 4091978, Japanese Patent No. 3448626, and the contents of these publications are incorporated in the present invention.

<Other configurations>
(Color filter)
When the light source uses the blue light having a light source of 500 nm or less, the pixel in the present invention can be formed using various known RGB pixel forming methods. For example, a desired black matrix and R, G, and B pixel patterns can be formed on a glass substrate by using a photomask and a photoresist, and colored inks for R, G, and B pixels can be used. Using an inkjet printing apparatus in a black matrix having a predetermined width and an area (a concave portion surrounded by convex portions) divided by every n black matrix wider than the width of the black matrix It is also possible to produce a color filter composed of R, G, and B patterns by discharging the ink composition until a desired concentration is achieved. After image coloring, each pixel and the black matrix may be completely cured by baking or the like.
Preferred characteristics of the color filter are described in Japanese Patent Application Laid-Open No. 2008-083611 and the like, and the content of this publication is incorporated in the present invention.
For example, it is preferable that one wavelength is 590 nm to 610 nm and the other wavelength is 470 nm to 500 nm in the color filter showing green. In addition, it is preferable that one of the wavelengths of the green color filter that has a transmittance that is half of the maximum transmittance is 590 nm to 600 nm. Furthermore, it is preferable that the maximum transmittance of the color filter showing green is 80% or more. In the color filter exhibiting green, the wavelength having the maximum transmittance is preferably 530 nm or more and 560 nm or less.
In the green color filter, the transmittance at the wavelength of the emission peak is preferably 10% or less of the maximum transmittance.
The color filter exhibiting red color preferably has a transmittance at 580 nm or more and 590 nm or less of 10% or less of the maximum transmittance.

  As a color filter pigment, blue is C.I. I. Pigment Blue 15: 6 and complementary color pigment C.I. I. Pigment Violet 23 is used. In red, C.I. I. Pigment Red 254 as a complementary color C.I. I. Pigment Yellow 139 is used. As the green pigment, C.I. I. Pigment Green 36 (copper bromide phthalocyanine green), C.I. I. Pigment Green 7 (copper chloride phthalocyanine green) as a complementary color pigment C.I. I. Pigment Yellow 150 and C.I. I. Pigment Yellow 138 or the like is used. It can be controlled by adjusting the composition of these pigments. By increasing the composition of the complementary color pigment in a small amount with respect to the comparative example, the half-value wavelength on the long wavelength side can be set in the range of 590 nm to 600 nm. Currently, pigments are generally used. However, color filters using dyes may be used as long as they are pigments that can control spectroscopy and ensure process stability and reliability.

(Black matrix)
In the liquid crystal display device of the present invention, it is preferable that a black matrix is disposed between each pixel. Examples of the material for forming the black stripe include a material using a sputtered film of a metal such as chromium, and a light-shielding photosensitive composition in which a photosensitive resin and a black colorant are combined. Specific examples of the black colorant include carbon black, titanium carbon, iron oxide, titanium oxide, graphite, and the like. Among these, carbon black is preferable.

(Thin layer transistor)
The image display device of the present invention preferably further includes a TFT substrate having a thin layer transistor (hereinafter also referred to as TFT).
The thin film transistor preferably includes an oxide semiconductor layer having a carrier concentration of less than 1 × 10 ¹⁴ / cm ³ . A preferred embodiment of the thin layer transistor is described in Japanese Patent Application Laid-Open No. 2011-141522, and the content of this publication is incorporated in the present invention.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[Example 1]
<Production of retardation film (with absorbing material)>
(Preparation of cellulose acylate dope)
The following composition was placed in a mixing tank, stirred to dissolve each component, further heated to 90 ° C. for about 10 minutes, and then filtered through a filter paper having an average pore size of 34 μm and a sintered metal filter having an average pore size of 10 μm.
――――――――――――――――――――――――――――――――――
Cellulose acylate solution 1
――――――――――――――――――――――――――――――――――
Cellulose acylate having a degree of acetyl substitution of 2.43 100 parts by mass Sugar ester having the following skeleton A and acetyl group substitution degree of 8 10 parts by mass The following compound (1) 5 parts by mass Compound 3 0.017 parts by mass Methylene chloride 403 parts by mass Methanol 60 .2 parts by mass ――――――――――――――――――――――――――――――――――

Next, 100 parts by weight of the cellulose acylate solution 1 prepared by the above method was mixed with the following composition (mat agent dispersion) in an amount of 0.02 parts by weight of inorganic fine particles with respect to the cellulose acylate resin. A membrane dope was prepared.
――――――――――――――――――――――――――――――――――――
Matting agent dispersion ――――――――――――――――――――――――――――――――――――
-Matting agent (Aerosil R972) 0.2 parts by weight-Methylene chloride 72.4 parts by weight-Methanol 10.8 parts by weight-The above cellulose acylate solution 1 10.3 parts by weight -------- ―――――――――――――――――――――――――

The above-mentioned dope was cast using a band casting machine. The band was made of SUS.
The web (film) obtained by casting was peeled from the band, and then dried for 20 minutes in the tenter apparatus using a tenter apparatus that clips and conveys both ends of the web with clips. In addition, the drying temperature here means the film surface temperature of a film.
The obtained web (film) is peeled off from the band, and is sandwiched between clips. When the amount of residual solvent is 30 to 5% with respect to the mass of the entire film, the stretching temperature is 170 ° C. and the stretching ratio is fixed uniaxial stretching. It extended | stretched in the direction (lateral direction) orthogonal to a film conveyance direction using the tenter at 45%.
Thereafter, the clip was removed from the film and dried at 110 ° C. for 30 minutes. At this time, the cast film thickness was adjusted so that the film thickness after stretching was 64 μm.
The film subjected to the stretching treatment was sequentially subjected to a condensation prevention treatment, a wet heat treatment (water vapor contact treatment) and a heat treatment.
In the anti-condensation treatment, the film temperature (100 ° C.) was adjusted by applying dry air to the film.
In the wet heat treatment (water vapor contact treatment), the absolute humidity of the wet gas in the wet gas contact chamber (the wet heat treatment absolute humidity) is 300 g / m ^3, and the dew point of the wet gas is 10 times higher than the temperature of each film. The film was transported while maintaining a state where the temperature of the film (wet heat treatment temperature) was 100 ° C. for only the treatment time (60 seconds).
In the heat treatment, the absolute humidity of the gas in the heat treatment chamber (heat treatment absolute humidity) is set to 0 g / m ³ , the temperature of each film (heat treatment temperature) is set to the same temperature as the wet heat treatment temperature, and the treatment time (2 minutes) is maintained. did. The film surface temperature was determined from the average value obtained by attaching a tape-type thermocouple surface temperature sensor (ST series manufactured by Anri Keiki Co., Ltd.) to the film at three points.
The film thus obtained was used as the retardation film of Example 1.

<Preparation of polarizing plate>
According to Example 1 of Japanese Patent Laid-Open No. 2001-141926, a peripheral speed difference was given between two pairs of nip rolls, and iodine was adsorbed to a polyvinyl alcohol film stretched in the longitudinal direction to produce a polarizing film.
The retardation film of Example 1 was attached to one side of the polarizer using a polyvinyl alcohol-based adhesive.
A commercially available cellulose triacetate film (Fujitac TD80UF, manufactured by FUJIFILM Corporation) was subjected to saponification treatment and attached to the opposite side of the polarizer using a polyvinyl alcohol adhesive.
The transmission axis of the polarizer and the in-plane slow axis of the retardation film of Example 1 were arranged in parallel. Further, the transmission axis of the polarizer and the in-plane slow axis of the commercially available cellulose triacetate film were arranged to be orthogonal to each other. Thus, the polarizing plate of Example 1 was produced.

<Manufacture of liquid crystal display devices>
A commercially available liquid crystal display device (BenQ, trade name XT4242) was disassembled, the backlight unit was changed to the following RGB narrow-band backlight unit, and the liquid crystal display device of Example 1 was produced according to the following method.
The used RGB narrow-band backlight unit includes a blue light emitting diode (Nichia B-LED, main wavelength 465 nm, half-value width 20 nm) as a light source. In addition, a quantum dot member that emits fluorescence of green light having a center wavelength of 535 nm and a half-value width of 40 nm and red light having a center wavelength of 630 nm and a half-value width of 40 nm when blue light of the blue light-emitting diode is incident on the front portion of the light source is provided. .
In Example 1, a pair of polarizing plates and a pair of optical compensation sheets of a trade name XT4242 VA type (vertical alignment type) liquid crystal cell were peeled off, and instead of the polarizing plate of Example 1, the retardation film was the liquid crystal cell side, cellulose The acetate film was attached to the viewing side and the backlight side one by one through an adhesive so that the acetate film was on the side opposite to the liquid crystal cell. Note that Δnd representing the birefringence of the liquid crystal display device was Δnd = 300 nm. The crossed Nicols were arranged so that the transmission axis of the polarizing plate on the viewing side was in the vertical direction (that is, substantially vertical direction), and the transmission axis of the polarizing plate on the backlight side was in the horizontal direction (that is, substantially horizontal direction).
In the following Table 1, in the column of the transmission axis direction of the polarizer of the viewing side polarizing plate, the relationship with the slow axis of the retardation film contained in the viewing side polarizing plate, the protective film contained in the viewing side polarizing plate The relationship with the slow axis and the relationship with the substantially vertical direction or the substantially horizontal direction when the liquid crystal display device is arranged in parallel with the surface in which the in-plane direction of the panel includes the substantially vertical direction and the substantially horizontal direction are described.
In Table 1 below, the column of the direction in which the absorbance of the retardation film of the viewing side polarizing plate is maximized describes the relationship with the slow axis of the retardation film of the viewing side polarizing plate.
Although the relationship between the direction in which the absorbance of the retardation film on the backlight side is maximum and the slow axis on the backlight side is not described in Table 1, the position of the viewing side polarizing plate in each Example and Comparative Example is not described. The relationship between the direction in which the absorbance of the retardation film is maximized and the slow axis of the retardation film of the viewing side polarizing plate was the same.
In Table 1 below, the column of the transmission axis direction of the polarizer of the backlight side polarizing plate includes the relationship with the slow axis of the retardation film included in the backlight side polarizing plate, and is included in the backlight side polarizing plate. The relationship with the slow axis of the protective film and the relationship with the substantially vertical direction or the substantially horizontal direction when the liquid crystal display device is arranged in parallel with the plane in which the in-plane direction of the panel includes the substantially vertical direction and the substantially horizontal direction are described.
In Table 1 below, the column of the direction of the absorption axis of the polarizer of the backlight side polarizing plate describes the relationship with the direction in which the absorbance of the retardation film contained in the viewing side polarizing plate is maximized.

[Comparative Example 1]
A retardation film was formed in the same manner as in Example 1 except that the compound 3 was not added to the cellulose acylate solution 1 of Example 1.
The film thus obtained was used as the retardation film of Comparative Example 1.
A polarizing plate and a liquid crystal display device of Comparative Example 1 were produced in the same manner as in Example 1 except that the retardation film of Comparative Example 1 was used instead of the retardation film of Example 1.

[Comparative Example 2]
A liquid crystal display device of Comparative Example 2 was prepared in the same manner as in Example 1 except that the backlight unit in the liquid crystal display device of Example 1 was returned to the backlight unit originally incorporated in the commercially available liquid crystal display device. . The backlight unit of a commercially available liquid crystal display device emits light with a white LED, and unlike the RGB narrow-band backlight unit used in Example 1, it has a broad emission spectrum in the visible light range.

[Evaluation]
(Optical development of retardation film)
A polarizing prism was attached to an ultraviolet-visible absorption spectrum meter manufactured by Shimadzu Corporation, and polarization absorption measurement was performed in the direction perpendicular to the stretching direction of the retardation films or base materials of the Examples and Comparative Examples produced above.
In the retardation film of Example 1, the wavelength at which the absorbance is maximum (absorption maximum wavelength) is 595 nm, the half width of absorption is 43 nm, and the direction parallel to the retardation axis of the retardation film or substrate (stretching direction). It was found to have the maximum absorbance (absorption maximum). The maximum absorbance (absorbance for polarized light in the stretching direction) α at the absorption maximum wavelength was 0.21, and the absorbance α⊥ for polarized light in the direction orthogonal to the stretching was 0.0525. Further, the obtained α was divided by α⊥ to obtain the value of α / α⊥.
On the other hand, in the retardation film of Comparative Example 1, no absorption maximum was observed in the visible light wavelength region.
Subsequently, Re of the retardation films of each Example and Comparative Example was measured at wavelengths of 450 nm, 535 nm, and 630 nm using KOBRA 21ADH (manufactured by Oji Scientific Instruments), and Rth was measured at the wavelength (535 nm).
Further, Re (630) obtained is divided by Re (535), Re (535) is divided by Re (450), and Re (630) is divided by Re (450) to obtain Re (630) / Re (535). ), Re (535) / Re (450) and Re (535) / Re (450).
Further, Re (535) / Re (450) obtained is divided by Re (630) / Re (535) to obtain {Re (535) / Re (450)} / {Re (630) / Re (535)}. The value was determined.
These results are shown in Table 1 below.

(Evaluation of liquid crystal display devices)
About the produced liquid crystal display device of each Example and a comparative example, using a measuring device (EZ-Contrast160D, the product made by ELDIM), the front luminance and the polar angle were fixed to 60 degrees, and the azimuth was changed 0 to 360 degrees. The black color shift Δxy was measured. The front luminance was expressed as a relative value based on the value in Example 1.
Further, the color gamut of the liquid crystal display device was measured by the method described in JP2012-3073A.
The results are shown in Table 1 below.

From Table 1 above, the retardation film of Example 1 has a value of {Re (535) / Re (450)} / {Re (630) / Re (535)} within the scope of the present invention, and has chromatic dispersion. It can be understood that ideal inverse dispersion characteristics were obtained between three wavelengths of 450, 535, and 630 nm. On the other hand, it was found that the value of {Re (535) / Re (450)} / {Re (630) / Re (535)} in the retardation film of Comparative Example 1 was outside the scope of the present invention.
From the results shown in Table 1 above, it can be understood that the liquid crystal display device of Example 1 maintains the front luminance and improves the black color shift. On the other hand, from Comparative Example 1, the retardation film of Comparative Example 1 in which the value of {Re (535) / Re (450)} / {Re (630) / Re (535)} is outside the scope of the present invention was used. The liquid crystal display device was found to have a poor black color shift. From the comparative example 2, it turned out that the liquid crystal display device using the backlight which is outside the range of the present invention has poor front luminance.

1 viewing side polarizing plate F1 polarizing plate protective film (outer side polarizing plate protective film of viewing side polarizing plate)
2 viewing side polarizer F2 retardation film (inner side polarizing plate protective film of viewing side polarizing plate)
3 Absorbing Layer 4 Base Material 11 Liquid Crystal Cell 21 Backlight Side Polarizer 22 Backlight Side Polarizer F3 Retardation Film (Inner Side Polarizer Protective Film for Backlight Side Polarizer)
23 absorption layer 24 base material F4 polarizing plate protective film (outer side polarizing plate protective film of backlight side polarizing plate)
31 Backlight unit 41 Liquid crystal display device

Claims (17)

A retardation film, a liquid crystal cell, and a backlight unit;
The retardation film has a maximum absorbance at 595 ± 10 nm or 655 ± 10 nm, and satisfies the following formulas (1) and (2);
Blue light having a light emission center wavelength in a wavelength band of 430 to 480 nm, and
Green light having an emission center wavelength in a wavelength band of 500 to 600 nm;
Emitting red light having an emission center wavelength in a wavelength band of 600 to 650 nm;
Liquid crystal display device.
Formula (1) 2 ≦ α / α⊥ ≦ 6
(In the formula (1), α represents the maximum absorbance of the retardation film, and α⊥ represents the absorbance with respect to the wavelength at which the absorbance in the direction orthogonal to the direction in which the absorbance of the retardation film is maximized. )
Formula (2) 1.11 ≦ Re (630) / Re (535) ≦ 1.25
(In formula (2), Re (λ) represents retardation in the in-plane direction of retardation film at wavelength λ nm (unit: nm).)   2. The liquid crystal display device according to claim 1, wherein a half-value width of the blue light, a half-value width of the green light, and a half-value width of the red light are all 100 nm or less.   The liquid crystal display device according to claim 1, wherein the half-width of the absorbance peak of the retardation film is 10 to 50 nm. The liquid crystal display device according to claim 1, wherein the retardation film satisfies the following formula (3).
Formula (3) 0.90 ≦ {Re (535) / Re (450)} / {Re (630) / Re (535)} ≦ 1.1
(In Formula (3), Re (λ) represents retardation (unit: nm) in the in-plane direction of the retardation film at the wavelength λ nm.)   The liquid crystal display device according to any one of claims 1 to 4, wherein a direction in which the absorbance of the retardation film has a maximum value and a slow axis of the retardation film are parallel to each other.   The liquid crystal display device according to claim 1, wherein the retardation film has an absorbing material having a maximum absorbance at 595 ± 10 nm or 655 ± 10 nm.   The liquid crystal display device according to claim 6, wherein the retardation film is a laminate of a base material and an absorbing layer containing the absorbing material, or a single layer of the base material containing the absorbing material. Between the liquid crystal cell and the backlight unit, and having a polarizer on at least one of the opposite side of the backlight unit with respect to the liquid crystal cell,
The liquid crystal display device according to claim 1, wherein the direction in which the absorbance of the retardation film is maximum is parallel to the absorption axis of the polarizer. The liquid crystal cell has a viewing side polarizer on the opposite side of the backlight unit, and has at least one retardation film between the viewing side polarizer and the liquid crystal cell,
The backlight side polarizer is provided between the liquid crystal cell and the backlight unit, and at least one retardation film is provided between the backlight side polarizer and the liquid crystal cell. The liquid crystal display device according to any one of the above. A blue light emitting diode that emits the blue light;
The liquid crystal display device according to claim 1, comprising a fluorescent material that emits the green light and the red light when the blue light of the blue light emitting diode is incident. The fluorescent material is a quantum dot member;
The liquid crystal display device according to claim 10, wherein the quantum dot member is disposed between the optical sheet member and the blue light source. Has a maximum absorbance at 595 ± 10 nm,
The following formulas (1) to (3) are satisfied,
A retardation film, wherein the direction in which the absorbance of the retardation film is maximum is parallel to the slow axis of the retardation film.
Formula (1) 2 ≦ α / α⊥ ≦ 6
(In the formula (1), α represents the maximum absorbance of the retardation film, and α⊥ represents the absorbance with respect to the wavelength at which the absorbance in the direction orthogonal to the direction in which the absorbance of the retardation film is maximized. )
Formula (2) 1.11 ≦ Re (630) / Re (535) ≦ 1.25
Formula (3) 0.90 ≦ {Re (535) / Re (450)} / {Re (630) / Re (535)} ≦ 1.1
(In the formulas (2) and (3), Re (λ) represents the retardation (unit: nm) in the in-plane direction of the retardation film at the wavelength λ nm.) Has a maximum absorbance at 655 ± 10 nm,
The following formulas (1) to (3) are satisfied,
A phase difference film in which the direction in which the absorbance of the phase difference film is maximized is perpendicular to the slow axis of the phase difference film.
Formula (1) 2 ≦ α / α⊥ ≦ 6
(In the formula (1), α represents the maximum absorbance of the retardation film, and α⊥ represents the absorbance with respect to the wavelength at which the absorbance in the direction orthogonal to the direction in which the absorbance of the retardation film is maximized. )
Formula (2) 1.11 ≦ Re (630) / Re (535) ≦ 1.25
Formula (3) 0.90 ≦ {Re (535) / Re (450)} / {Re (630) / Re (535)} ≦ 1.1
(In the formulas (2) and (3), Re (λ) represents the retardation (unit: nm) in the in-plane direction of the retardation film at the wavelength λ nm.)   The retardation film of Claim 12 or 13 whose half width of the absorbance peak of the said retardation film is 10-50 nm.   The retardation film according to claim 12, wherein the retardation film has a light-absorbing material having a maximum absorbance at 595 ± 10 nm or 655 ± 10 nm.   The retardation film according to claim 15, wherein the retardation film is a laminate of a base material and an absorption layer containing the light absorbing material, or a single layer of the base material containing the light absorbing material. A polarizer,
A polarizing plate having at least one retardation film according to any one of claims 12 to 16.

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