Method for selecting a combination of backlight source and polarizing plate in image display device and liquid crystal display device

Abstract

To provide a liquid crystal display device which has a wide reproducible color gamut and in which color spots are not noticeable even when an image display device emits a steep emission spectrum in the red region, and in which color spots are not noticeable even when a light source having a steep emission spectrum in the red region, such as a KSF phosphor, is used as a backlight light source. [Solution] An image display device having an image display cell and at least one polarizing plate, wherein the at least one polarizing plate is one in which light incident on the polarizing plate has a plurality of peak groups in the range of 600 to 650 nm, and the polarizing plate has a polarizer protective film whose 45-degree light source compatibility index (FI(45)) calculated by the following formula 1 is 0.4 or more and 0.62 or less. FI(45)=Wd / [Wc / (Rob(45) / Wc)] Equation 1

Description

[Technical Field]

[0001] The present invention relates to an image display device, typically an image display device that emits an emission spectrum having a steep peak in the red region, and more particularly to a liquid crystal display device that has a wide range of expressibility on the CIE (Commission Internationale de l'Eclairage) chromaticity diagram by using a light source whose emission spectrum has a steep peak in the red region. [Background technology]

[0002] It is known that when birefringent films such as polyester films are used under fluorescent or cold cathode fluorescent lamps, rainbow spots due to retardation occur. For this reason, optically isotropic cellulose-based films have been used as protective films for polarizers used in liquid crystal displays.

[0003] In recent years, a technology has been proposed for eliminating rainbow spots in liquid crystal display devices by combining a polarizing plate using a polyester film having an in-plane retardation of 3,000 to 30,000 nm as a polarizer protective film with a white light source having a continuous emission spectrum (for example, Patent Document 1). This technology has been highly praised for the excellent properties of polyester as a polarizer protective film, such as excellent mechanical strength, transparency, low moisture absorption, and low moisture permeability, and has also been put to practical use in liquid crystal display devices due to the reduction in price and widespread use of white light-emitting diodes that combine blue light-emitting diodes with yellow phosphors. Recently, there has been a demand for a wider range of color reproduction in LCD devices, and light sources with a steep emission peak in the red region of the emission spectrum called KSF phosphor (a phosphor made by adding Mn to K2SiF6 crystal) are increasingly being used as white light-emitting diodes. However, when a light source containing this KSF phosphor is combined with a polarizing plate using a high-retardation polyester film as a polarizer protective film, red striped color spots are observed in some areas, and further improvement in suppressing color spots is required. In liquid crystal display devices using such KSF light sources, methods for suppressing color spots have been proposed, such as a method of setting the refractive index of the polyester film in the transmission axis direction of the polarizing plate to 1.53 to 1.62 (e.g., Patent Document 2) and a method of providing an antireflection layer and / or a low-reflection layer on at least one surface of the polyester film (e.g., Patent Document 3), but there is room for further improvement. In particular, color spots are likely to occur when a polyester film is used for the polarizing plate on the light source side, so further improvement is required. Furthermore, in the case of high-definition image display devices such as 4K and 8K, even large image display devices are often viewed up close, making even small defects noticeable, and improvements to these defects are also required.To take advantage of the characteristics of image display devices with a wide color gamut, polarizer protective films also require high transparency. Furthermore, in black display areas or when the power is turned off, interference colors due to optical interference in the coating layer of the polarizer protective film become noticeable, and this interference color also causes problems such as a deterioration in display quality and the appearance quality of the display device itself. Large image display devices in particular are often used in show windows, lobbies of luxury hotels, luxury shops, etc., and are therefore required to have excellent appearance even when the power is turned off. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2011 / 162198 [Patent Document 2] International Publication No. 2017 / 010444 [Patent Document 3] International Publication No. 2017 / 065148 Summary of the Invention [Problem to be solved by the invention]

[0005] One object of the present invention is to provide an image display device that has a wide color reproduction gamut and inconspicuous color spots even when the image display device emits an emission spectrum with a steep peak in the red region, and furthermore, an image display device that has inconspicuous interference colors when the light is off. Another object of the present invention is to provide a liquid crystal display device that has a wide color reproduction gamut and inconspicuous color spots even when a light source having an emission spectrum with a steep peak in the red region, such as a KSF phosphor, is used as a backlight light source, and furthermore, an image display device that has inconspicuous interference colors when the light is off. Another object of the present invention is to provide an image display device in which defects are not noticeable even when the image is high-definition. Another object of the present invention is to provide an image display device that can reproduce vivid colors with high transparency. Still another object of the present invention is to provide a display device that is less likely to produce color spots across the entire screen, even when viewed from an oblique angle, particularly in the case of a large display device, and that has a uniform color tone. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to achieve this object and have completed the present invention. That is, the present invention includes the following aspects.

[0007] Section 1: An image display device having an image display cell and at least one polarizing plate, The at least one polarizing plate is a polarizing plate in which light incident on the polarizing plate has a plurality of peak groups in the range of 600 to 650 nm, and the polarizing plate has a polarizer protective film having a 45-degree light source compatibility index (FI(45)) calculated by the following formula 1 of 0.4 or more and 0.62 or less. FI(45)=Wd / [Wc / (Rob(45) / Wc)] Equation 1 Rob(45): Retardation of the polarizer protective film measured in the in-plane direction of the film at an angle of 45 degrees from the slow axis direction to the fast axis direction, and in a direction tilted by 50 degrees from the normal direction. Wd: Peak-to-peak distance (nm) Wc: central wavelength of the peak group (nm)

[0008] Section 2: Item 2. The image display device according to item 1, wherein the polarizer protective film has a 30-degree light source compatibility index (FI(30)) calculated by the following formula 2 and a 60-degree light source compatibility index (FI(60)) calculated by the following formula 3, both of which are 0.35 or more and 0.68 or less. FI(30)=Wd / [Wc / (Rob(30) / Wc)] Equation 2 FI(60)=Wd / [Wc / (Rob(60) / Wc)] Equation 3 Rob(30): Retardation of the polarizer protective film measured in the in-plane direction of the film at an angle of 30 degrees from the slow axis direction to the fast axis direction and inclined by 50 degrees from the normal direction Rob(60): Retardation of the polarizer protective film measured in the in-plane direction of the film at an angle of 60 degrees from the slow axis direction to the fast axis direction, and in a direction tilted by 50 degrees from the normal direction Wd: Peak-to-peak distance (nm) Wc: central wavelength of the peak group (nm)

[0009] Section 3: Item 3. The image display device according to item 2, wherein the polarizer protective film has a ratio (ΔFI / FI(45)) of the difference between FI(30) and FI(60) (ΔFI=FI(60)−FI(30)) to FI(45) of 0.2 or more and 0.35 or less.

[0010] Section 4: An image display device having an image display cell and at least one polarizing plate, the at least one polarizing plate is a polarizing plate in which light incident on the polarizing plate has a plurality of peak groups in the range of 600 to 650 nm; the at least one polarizing plate has a polarizer and at least one polarizer protective film; the at least one polarizer protective film has a 45-degree light source suitability index (FI(45)) calculated by the following formula 1, measured at 100 mm intervals along the long side direction and at 100 mm intervals along the short side direction, both of which are 0.4 or more and 0.62 or less, An image display device in which both the value obtained by subtracting the minimum value from the maximum value of the FI(45) measured at 100 mm intervals along the long side direction and the value obtained by subtracting the minimum value from the maximum value of the FI(45) measured at 100 mm intervals along the short side direction are 0.026 or less. FI(45)=Wd / [Wc / (Rob(45) / Wc)] Equation 1 Rob(45): Retardation of the polarizer protective film measured in the in-plane direction of the film at an angle of 45 degrees from the slow axis direction to the fast axis direction, and in a direction tilted by 50 degrees from the normal direction. Wd: Peak-to-peak distance (nm) Wc: central wavelength of the peak group (nm)

[0011] Section 5: Item 5. The image display device according to item 4, wherein the at least one polarizer protective film has a 30-degree light source suitability index (FI(30)) calculated by the following formula 2 and a 60-degree light source suitability index (FI(60)) calculated by the following formula 3, both of which are measured at 100 mm intervals along the long side direction and at 100 mm intervals along the short side direction, and are 0.35 or more and 0.68 or less: FI(30)=Wd / [Wc / (Rob(30) / Wc)] Equation 2 FI(60)=Wd / [Wc / (Rob(30) / Wc)] Equation 3 Rob(30): Retardation of the polarizer protective film measured in the in-plane direction of the film at an angle of 30 degrees from the slow axis direction to the fast axis direction and inclined by 50 degrees from the normal direction Rob(60): Retardation of the polarizer protective film measured in the in-plane direction of the film at an angle of 60 degrees from the slow axis direction to the fast axis direction, and in a direction tilted by 50 degrees from the normal direction Wd: Peak-to-peak distance (nm) Wc: central wavelength of the peak group (nm)

[0012] Item 6: Item 6. The image display device according to item 5, wherein ΔFI / FI(45), which is the ratio of the difference between FI(30) and FI(60) to FI(45) (ΔFI=FI(60)-FI(30)), of the at least one polarizer protective film is measured at 100 mm intervals along the long side direction and at 100 mm intervals along the short side direction, and both of these values ​​are 0.2 or more and 0.35 or less.

[0013] Section 7: Item 7. The image display device according to any one of items 1 to 6, wherein the polarizer protective film contains one or less foreign particles having a major axis of 100 μm or more.

[0014] Section 8: Item 8. The image display device according to any one of items 1 to 7, wherein the amount of antimony atoms in the residue insoluble in a mixed solvent of parachlorophenol and tetrachloroethane in the polarizer protective film is 50 mg or less per 1 kg of a resin constituting the polarizer protective film.

[0015] Section 9: Item 9. The image display device according to any one of items 1 to 8, wherein the polarizer protective film has an easy-adhesion layer containing particles having a refractive index of 1.7 to 3 on at least one surface thereof.

[0016] Section 10: Item 10. The image display device according to any one of items 1 to 9, wherein the light having a plurality of peak groups in the range of 600 to 650 nm incident on the polarizing plate is derived from excited emission of a red phosphor activated with a tetravalent manganese ion.

[0017] Section 11: An image display device having an image display cell and at least one polarizing plate, the at least one polarizing plate has a polarizer protective film having a retardation (Rob(45)) of 7500 nm or more and 11700 nm or less when measured in an in-plane direction of the film at an angle of 45 degrees from the slow axis direction to the fast axis direction and in a direction tilted by 50 degrees from the normal direction, The image display device includes light incident on the at least one polarizing plate, which emits light due to excitation of a red phosphor activated with tetravalent manganese ions.

[0018] Section 12: An image display device having an image display cell and at least one polarizing plate, the at least one polarizing plate has a polarizer and at least one polarizer protective film; the retardation (Rob(45)) of the at least one polarizer protective film measured in an in-plane direction of the film from the slow axis direction toward the fast axis direction at an angle of 45 degrees and inclined by 50 degrees from the normal direction is 7,500 nm or more and 11,700 nm or less, both of which are measured at 100 mm intervals along the long side direction and at 100 mm intervals along the short side direction; The value obtained by subtracting the minimum value from the maximum value of the Rob(45) measured at 100 mm intervals along the long side direction, and the value obtained by subtracting the minimum value from the maximum value of the Rob(45) measured at 100 mm intervals along the short side direction are both 500 nm or less, The image display device includes light incident on the at least one polarizing plate, which emits light due to excitation of a red phosphor activated with tetravalent manganese ions.

[0019] Section 13: Item 13. The image display device according to item 11 or 12, wherein the polarizer protective film contains one or less foreign particles having a major axis of 100 μm or more.

[0020] Section 14: Item 14. The image display device according to any one of items 11 to 13, wherein the amount of antimony atoms in the residue insoluble in a mixed solvent of parachlorophenol and tetrachloroethane in the polarizer protective film is 50 mg or less per kg of resin constituting the polarizer protective film.

[0021] Section 15: Item 15. The image display device according to any one of items 11 to 14, wherein the polarizer protective film has an easy-adhesion layer containing particles having a refractive index of 1.7 to 3 on at least one surface thereof.

[0022] Section 16: The red phosphor activated with the tetravalent manganese ions is K2SiF6:Mn 4+ Item 16. The image display device according to any one of items 11 to 15, wherein the red phosphor is represented by the formula:

[0023] Section 17: Item 17. The image display according to any one of items 11 to 16, wherein the polarizer protective film has a haze of 5% or less.

[0024] Section 18: Item 18. The image display device according to any one of items 11 to 17, wherein the polarizer protective film has a surface roughness (SRa) of 0.05 μm or less on at least one surface thereof.

[0025] Section 19: Item 19. The image display device according to any one of items 11 to 18, wherein the angle (acute angle side) between the slow axis of the polarizer protective film in the film plane and the absorption axis of the polarizer is 83 degrees or more and 90 degrees or less, or 0 degrees or more and 7 degrees or less.

[0026] Section 20: Item 20. The image display device according to any one of items 11 to 19, wherein the polarizing plate has a λ / 4 wavelength layer on the surface of the polarizer opposite to the surface on which the polarizer protective film is laminated.

[0027] Section 21: 21. The image display device according to any one of items 1 to 20, which is an electroluminescence image display device.

[0028] Section 22: A liquid crystal display device having a backlight light source, a light source-side polarizing plate, a liquid crystal cell, and a viewer-side polarizing plate, the emission spectrum of the backlight light source has a plurality of peaks in the range of 600 to 650 nm, A liquid crystal display device, wherein at least one of the light source side polarizing plate and the viewer side polarizing plate is a polarizing plate having a polarizer protective film having a 45-degree light source compatibility index (FI(45)) calculated by the following formula 1 of 0.4 or more and 0.62 or less. FI(45)=Wd / [Wc / (Rob(45) / Wc)] Equation 1 Rob(45): Retardation of the polarizer protective film measured in the in-plane direction of the film at an angle of 45 degrees from the slow axis direction to the fast axis direction, and in a direction tilted by 50 degrees from the normal direction. Wd: Peak-to-peak distance (nm) Wc: central wavelength of the peak group (nm)

[0029] Section 23: Item 23. The liquid crystal display device according to item 22, wherein the polarizer protective film has a 30-degree light source compatibility index (FI(30)) calculated by the following formula 2 and a 60-degree light source compatibility index (FI(60)) calculated by the following formula 3, both of which are 0.35 or more and 0.68 or less: FI(30)=Wd / [Wc / (Rob(30) / Wc)] Equation 2 FI(60)=Wd / [Wc / (Rob(60) / Wc)] Equation 3 Rob(30): Retardation of the polarizer protective film measured in the in-plane direction of the film at an angle of 30 degrees from the slow axis direction to the fast axis direction and inclined by 50 degrees from the normal direction Rob(60): Retardation of the polarizer protective film measured in the in-plane direction of the film at an angle of 60 degrees from the slow axis direction to the fast axis direction, and in a direction tilted by 50 degrees from the normal direction Wd: Peak-to-peak distance (nm) Wc: central wavelength of the peak group (nm)

[0030] Section 24: Item 24. The liquid crystal display device according to item 23, wherein the polarizer protective film has a ratio (ΔFI / FI(45)) of the difference between FI(30) and FI(60) (ΔFI=FI(60)−FI(30)) to FI(45) of 0.2 or more and 0.35 or less.

[0031] Section 25: Item 25. The liquid crystal display device according to any one of items 22 to 24, wherein the viewer-side polarizing plate is a polarizing plate having a polarizer protective film having a 45-degree light source compatibility index (FI(45)) calculated by the formula 1 above of 0.4 or more and 0.62 or less.

[0032] Section 26: Item 26. The liquid crystal display device according to any one of items 22 to 25, wherein the light source side polarizing plate is a polarizing plate having a polarizer protective film having a 45-degree light source compatibility index (FI(45)) calculated by the formula 1 above of 0.4 to 0.62.

[0033] Section 27: A liquid crystal display device having a backlight light source, a light source-side polarizing plate, a liquid crystal cell, and a viewer-side polarizing plate, the emission spectrum of the backlight light source has a plurality of peaks in the range of 600 to 650 nm, At least one of the light-source-side polarizing plate and the viewer-side polarizing plate has a polarizer and at least one polarizer protective film, the at least one polarizer protective film has a 45-degree light source suitability index (FI(45)) calculated by the following formula 1, measured at 100 mm intervals along the long side direction and at 100 mm intervals along the short side direction, both of which are 0.4 or more and 0.62 or less, A liquid crystal display device, wherein both the value obtained by subtracting the minimum value from the maximum value of the FI(45) measured at 100 mm intervals along the long side direction and the value obtained by subtracting the minimum value from the maximum value of the FI(45) measured at 100 mm intervals along the short side direction are 0.026 or less. FI(45)=Wd / [Wc / (Rob(45) / Wc)] Equation 1 Rob(45): Retardation of the polarizer protective film measured in the in-plane direction of the film at an angle of 45 degrees from the slow axis direction to the fast axis direction, and in a direction tilted by 50 degrees from the normal direction. Wd: Peak-to-peak distance (nm) Wc: central wavelength of the peak group (nm)

[0034] Section 28: Item 28. The liquid crystal display device according to item 27, wherein the at least one polarizer protective film has a 30-degree light source suitability index (FI(30)) calculated by the following formula 2 and a 60-degree light source suitability index (FI(60)) calculated by the following formula 3, both of which are measured at 100 mm intervals along the long side direction and at 100 mm intervals along the short side direction, and are 0.35 or more and 0.68 or less: FI(30)=Wd / [Wc / (Rob(30) / Wc)] Equation 2 FI(60)=Wd / [Wc / (Rob(30) / Wc)] Equation 3 Rob(30): Retardation of the polarizer protective film measured in the in-plane direction of the film at an angle of 30 degrees from the slow axis direction to the fast axis direction and inclined by 50 degrees from the normal direction Rob(60): Retardation of the polarizer protective film measured in the in-plane direction of the film at an angle of 60 degrees from the slow axis direction to the fast axis direction, and in a direction tilted by 50 degrees from the normal direction Wd: Peak-to-peak distance (nm) Wc: central wavelength of the peak group (nm)

[0035] Section 29: Item 29. The liquid crystal display device according to item 28, wherein ΔFI / FI(45), which is the ratio of the difference between FI(30) and FI(60) to FI(45) (ΔFI=FI(60)-FI(30)), of the at least one polarizer protective film is 0.2 or more and 0.35 or less, both as measured at 100 mm intervals along the long side direction and as measured at 100 mm intervals along the short side direction.

[0036] Section 30: The viewer-side polarizing plate is The 45-degree light source compatibility index (FI(45)) calculated by the formula 1 is measured at 100 mm intervals along the long side direction and at 100 mm intervals along the short side direction, and both values ​​are 0.4 or more and 0.62 or less, The value obtained by subtracting the minimum value from the maximum value of the FI (45) measured at 100 mm intervals along the long side direction, and the value obtained by subtracting the minimum value from the maximum value of the FI (45) measured at 100 mm intervals along the short side direction are both 0.026 or less. 30. The liquid crystal display device according to any one of items 27 to 29, wherein the polarizing plate has a polarizer protective film.

[0037] Section 31: the light source side polarizing plate is The 45-degree light source compatibility index (FI(45)) calculated by the formula 1 is measured at 100 mm intervals along the long side direction and at 100 mm intervals along the short side direction, and both values ​​are 0.4 or more and 0.62 or less, The value obtained by subtracting the minimum value from the maximum value of the FI (45) measured at 100 mm intervals along the long side direction, and the value obtained by subtracting the minimum value from the maximum value of the FI (45) measured at 100 mm intervals along the short side direction are both 0.026 or less. Item 31. The liquid crystal display device according to any one of items 27 to 30, wherein the polarizing plate has a polarizer protective film.

[0038] Section 32: Item 32. The liquid crystal display device according to any one of items 22 to 31, wherein the polarizer protective film contains one or less foreign particles having a major axis of 100 μm or more.

[0039] Section 33: Item 33. The liquid crystal display device according to any one of items 22 to 32, wherein the amount of antimony atoms in the residue insoluble in a mixed solvent of parachlorophenol and tetrachloroethane in the polarizer protective film is 50 mg or less per kg of resin constituting the polarizer protective film.

[0040] Section 34: Item 34. The liquid crystal display device according to any one of items 22 to 33, wherein the polarizer protective film has an easy-adhesion layer containing particles having a refractive index of 1.7 to 3 on at least one surface thereof.

[0041] Section 35: Item 35. The liquid crystal display device according to any one of items 22 to 34, wherein the backlight source causes a red phosphor activated with tetravalent manganese ions to emit light in response to excitation light.

[0042] Section 36: The backlight source emits K2SiF6:Mn 4+ Item 36. The liquid crystal display device according to item 35, wherein the liquid crystal display device emits light from a red phosphor represented by the following formula:

[0043] Section 37: A liquid crystal display device having a backlight light source, a light source-side polarizing plate, a liquid crystal cell, and a viewer-side polarizing plate, the backlight source causes a red phosphor activated with tetravalent manganese ions to emit light by excitation light, A liquid crystal display device, wherein at least one of the light source-side polarizing plate and the viewer-side polarizing plate is a polarizing plate having a polarizer protective film whose retardation (Rob(45)) is 7500 nm or more and 11700 nm or less when measured in a direction tilted 50 degrees from the normal direction at an angle of 45 degrees from the slow axis direction to the fast axis direction in the in-plane direction of the film.

[0044] Section 38: Item 38. The liquid crystal display device according to item 37, wherein both Rob(30) and Rob(60) of the polarizer protective film are 6570 nm or more and 12200 nm or less.

[0045] Section 39: Item 39. The liquid crystal display device according to item 38, wherein the difference between Rob(30) and Rob(60) (ΔRob=Rob(60)−Rob(30)) of the polarizer protective film is 1880 nm or more and 3400 nm or less.

[0046] Section 40: Item 40. The liquid crystal display device according to any one of items 37 to 39, wherein the viewer-side polarizing plate is a polarizing plate having a polarizer protective film having Rob(45) of 7500 nm or more and 11700 nm or less.

[0047] Section 41: 41. The liquid crystal display device according to any one of items 37 to 40, wherein the light source side polarizing plate is a polarizing plate having a polarizer protective film whose Rob(45) is 7500 nm or more and 11700 nm or less.

[0048] Section 42: A liquid crystal display device having a backlight light source, a light source-side polarizing plate, a liquid crystal cell, and a viewer-side polarizing plate, the backlight source causes a red phosphor activated with tetravalent manganese ions to emit light by excitation light, At least one of the light-source-side polarizing plate and the viewer-side polarizing plate has a polarizer and at least one polarizer protective film, the retardation (Rob(45)) of the at least one polarizer protective film measured in an in-plane direction of the film from the slow axis direction toward the fast axis direction at an angle of 45 degrees and inclined by 50 degrees from the normal direction is 7,500 nm or more and 11,700 nm or less, both of which are measured at 100 mm intervals along the long side direction and at 100 mm intervals along the short side direction; A liquid crystal display device in which both the value obtained by subtracting the minimum value from the maximum value of the Rob(45) measured at 100 mm intervals along the long side direction and the value obtained by subtracting the minimum value from the maximum value of the Rob(45) measured at 100 mm intervals along the short side direction are 500 nm or less.

[0049] Section 43: Item 43. The liquid crystal display device according to item 42, wherein the Rob(30) and the Rob(60) of the polarizer protective film are measured at 100 mm intervals along the long side direction and at 100 mm intervals along the short side direction, and are both 6570 nm or more and 12200 nm or less.

[0050] Section 44: Item 44. The liquid crystal display device according to item 43, wherein the difference between Rob(30) and Rob(60) (ΔRob=Rob(60)-Rob(30)) of the polarizer protective film, measured at 100 mm intervals along the long side direction and at 100 mm intervals along the short side direction, is 1880 nm or more and 3400 nm or less.

[0051] Section 45: Item 45. The liquid crystal display device according to any one of Items 37 to 44, wherein the viewer-side polarizing plate is a polarizing plate having a polarizer protective film such that both of the Rob(45) values ​​measured at 100 mm intervals along the long side direction and at 100 mm intervals along the short side direction are 7500 nm or more and 11700 nm or less.

[0052] Section 46: Item 46. The liquid crystal display device according to any one of Items 37 to 45, wherein the light-source-side polarizing plate is a polarizing plate having a polarizer protective film such that both of the Rob(45) values ​​measured at 100 mm intervals along the long side direction and at 100 mm intervals along the short side direction are 7500 nm or more and 11700 nm or less.

[0053] Section 47: Item 47. The liquid crystal display device according to any one of items 37 to 46, wherein the polarizer protective film contains one or less foreign particles having a major axis of 100 μm or more.

[0054] Section 48: Item 48. The liquid crystal display device according to any one of items 37 to 47, wherein the amount of antimony atoms in the residue insoluble in a mixed solvent of parachlorophenol and tetrachloroethane in the polarizer protective film is 50 mg or less per kg of resin constituting the polarizer protective film.

[0055] Section 49: Item 49. The liquid crystal display device according to any one of items 37 to 48, wherein the polarizer protective film has an easy-adhesion layer containing particles having a refractive index of 1.7 to 3 on at least one surface thereof.

[0056] Section 50: The red phosphor activated with the tetravalent manganese ions is K2SiF6:Mn 4+ 50. The liquid crystal display device according to any one of items 37 to 49, wherein the red phosphor is represented by the formula:

[0057] Section 51: 51. The image display according to any one of items 37 to 50, wherein the haze of the polarizer protective film is 5% or less.

[0058] Section 52: 52. The image display according to any one of items 37 to 51, wherein the polarizer protective film has a surface roughness (SRa) of 0.05 μm or less on at least one surface thereof.

[0059] Section 53: Item 53. The liquid crystal display device according to any one of items 37 to 52, wherein the haze of the polarizing plate having the polarizer protective film is 5% or less.

[0060] Section 54: Item 54. The liquid crystal display device according to any one of items 37 to 53, wherein the SRa of the surface of the polarizing plate having the polarizer protective film opposite to the liquid crystal cell is 0.05 μm or less.

[0061] Section 55: 55. The liquid crystal display according to any one of items 37 to 54, wherein the polarizer protective film has an SRz of 1.0 μm or less.

[0062] Section 56: 56. The liquid crystal display according to any one of items 37 to 55, wherein the SRz of the surface of the polarizing plate having the polarizer protective film opposite to the liquid crystal cell is 1.0 μm or less.

[0063] Section 57: Item 57. The liquid crystal display device according to any one of items 37 to 56, wherein the polarizer protective film has a functional layer on a surface opposite to the polarizer, and the reflectance measured from the functional layer side is 5% or less.

[0064] Section 58: Item 58. The liquid crystal display device according to any one of items 37 to 57, wherein the angle (acute angle side) between the slow axis of the polarizer protective film in the film plane and the absorption axis of the polarizer in the light-source-side polarizing plate or the viewer-side polarizing plate is 83 degrees or more and 90 degrees or less, or 0 degrees or more and 7 degrees or less.

[0065] Section 59: Item 59. The liquid crystal display device according to any one of items 37 to 58, wherein either or both of the light-source-side polarizing plate and the viewer-side polarizing plate have the resin film laminated on a surface of the polarizer opposite to the liquid crystal cell, and any one of a cured resin layer, an optical compensation layer, an adhesive layer, and a zero-retardation resin film laminated on the liquid crystal cell side of the polarizer.

[0066] Section 60: A method for selecting a combination of a backlight light source and a polarizing plate in a liquid crystal display device having a backlight light source, a light source-side polarizing plate, a liquid crystal cell, and a viewer-side polarizing plate, comprising: (a) selecting a backlight source having an emission spectrum with a plurality of peaks in the range of 600 to 650 nm; and (b) a step of selecting at least one of the light source side polarizing plate and the viewer side polarizing plate, the polarizing plate having a polarizer protective film having a 45-degree light source compatibility index (FI(45)) calculated by the following formula 1 of 0.4 or more and 0.62 or less; A method comprising: FI(45)=Wd / [Wc / (Rob(45) / Wc)] Equation 1 Rob(45): Retardation of the polarizer protective film measured in the in-plane direction of the film at an angle of 45 degrees from the slow axis direction to the fast axis direction, and in a direction tilted by 50 degrees from the normal direction. Wd: Peak-to-peak distance (nm) Wc: central wavelength of the peak group (nm)

[0067] Section 61: A method for selecting a combination of a backlight light source and a polarizing plate in a liquid crystal display device having a backlight light source, a light source-side polarizing plate, a liquid crystal cell, and a viewer-side polarizing plate, comprising: (a) selecting a backlight source having an emission spectrum with a plurality of peaks in the range of 600 to 650 nm; and (b) at least one of the light source side polarizing plate and the viewer side polarizing plate, a step of selecting a polarizing plate having a polarizer protective film in which the 45-degree light source compatibility index (FI(45)) calculated by the following formula 1, measured at 100 mm intervals along the long side direction and at 100 mm intervals along the short side direction, is 0.4 or more and 0.62 or less, and both the value obtained by subtracting the minimum value from the maximum value of the FI(45) measured at 100 mm intervals along the long side direction and the value obtained by subtracting the minimum value from the maximum value of the FI(45) measured at 100 mm intervals along the short side direction are 0.026 or less; A method comprising: FI(45)=Wd / [Wc / (Rob(45) / Wc)] Equation 1 Rob(45): Retardation of the polarizer protective film measured in the in-plane direction of the film at an angle of 45 degrees from the slow axis direction to the fast axis direction, and in a direction tilted by 50 degrees from the normal direction. Wd: Peak-to-peak distance (nm) Wc: central wavelength of the peak group (nm)

[0068] Section 62: Item 62. The method according to item 60 or 61, wherein the polarizer protective film has one or less foreign particles with a major axis of 100 μm or more.

[0069] Section 63: Item 63. The method according to any one of items 60 to 62, wherein the amount of antimony atoms in the residue insoluble in the mixed solvent of parachlorophenol and tetrachloroethane in the polarizer protective film is 50 mg or less per kg of the resin constituting the polarizer protective film.

[0070] Section 64: Item 64. The method according to any one of Items 60 to 63, wherein the polarizer protective film has an easy-adhesion layer containing particles having a refractive index of 1.7 to 3 on at least one surface thereof. [Effects of the Invention]

[0071] The present invention can provide an image display device that has a wide reproducible color gamut and does not produce noticeable color spots even when the image display device emits an emission spectrum with a steep peak in the red region, and further provides an image display device that does not produce noticeable interference colors when the light is off.In particular, it can provide a liquid crystal display device that has a wide reproducible color gamut and does not produce noticeable color spots even when a light source having an emission spectrum with a steep peak in the red region, such as a KSF phosphor, is used as a backlight light source, and further provides a liquid crystal display device that has a wide reproducible color gamut and does not produce noticeable interference colors when the light is off. The present invention can provide an image display device in which defects are not noticeable even when it is a high-resolution image display device. The present invention can also provide an image display device with a wide color gamut that makes the most of highly transparent and vivid color reproducibility. Furthermore, the present invention can also provide a display device that is less likely to produce color spots across the entire screen, even when viewed obliquely, particularly in large display devices, and that has a uniform color tone. [Brief explanation of the drawings]

[0072] [Figure 1] 1 shows the emission spectrum of a white LED used in the examples and having K2SiF6:Mn4+ as a red phosphor. DETAILED DESCRIPTION OF THE INVENTION

[0073] (Image display device) In one embodiment, the image display device of the present invention is preferably an image display device in which light incident on the polarizing plate has a plurality of peaks (particularly, steep peaks) in the range of 600 to 650 nm. Examples of the image display device of the present invention include, but are not particularly limited to, a liquid crystal display device, an electroluminescence (EL) display device, and a micro LED. In the image display device of the present invention, examples of a method for emitting light having multiple peaks (particularly steep peaks) in the range of 600 to 650 nm include a method of exciting a phosphor capable of emitting light having multiple peaks (particularly steep peaks), such as a KSF phosphor (a phosphor in which Mn is added to a K2SiF6 crystal), to emit light, and a method of using a semiconductor laser in combination.

[0074] In the case of a liquid crystal display device, for example, a method can be used in which a blue or ultraviolet LED is used to excite a red KSF phosphor to emit light, thereby providing a white light backlight source. In the case of an electroluminescence display device, for example, a method in which a blue EL emitter is used to excite a red KSF phosphor to emit light and use it as a red pixel, or a method in which a blue EL emitter is used to excite a red KSF phosphor and a green phosphor to emit light to produce white light, and color filters are used to produce pixels of each color.

[0075] Although the present invention is not limited to a light-emitting method or a drawing method, a liquid crystal display device having a backlight light source, in which the emission spectrum of the backlight light source has multiple sharp peaks in the red region, will be described in detail below as a representative image display device. Note that the following description is not limited to liquid crystal display devices, unless it is specific to liquid crystal display devices.

[0076] (Backlight source) The liquid crystal display device of the present invention preferably uses a backlight source whose emission spectrum has multiple steep peaks in the range of 600 to 650 nm. Here, a steep peak means that the half-width is 6 nm or less, preferably 5 nm or less, and more preferably 4 nm or less. Note that the half-width is the half-width relative to one peak top. When two or more peaks are close to each other and the measured emission intensities overlap at a portion equal to or greater than half of the peak top, or when the peaks overlap with a broad peak, the half-width is determined by extrapolating from the slope immediately before the overlap. The multiple peaks (especially steep peaks) may form a peak group including adjacent peaks with a peak top separation of 7 nm or less (one peak may be a satellite peak of the other peak). The peak group may consist of only one single peak (also referred to as an independent peak), or may include a certain peak a (e.g., an independent peak) and all peaks b (e.g., satellite peaks) that exist within a peak top separation of 7 nm or less from peak a. The multiple peaks (especially steep peaks) preferably consist of multiple peak groups (e.g., a combination of one or more peak groups consisting of independent peaks and satellite peaks, and one or more peak groups consisting of only independent peaks). Note that methods for determining peak groups, independent peaks, and satellite peaks are as described below.

[0077] A specific example of a backlight light source is a light source that uses excitation light to emit a red phosphor activated with tetravalent manganese ions. The red phosphor activated with tetravalent manganese ions can emit red fluorescence when irradiated with excitation light. Light sources used for the excitation light include blue LEDs, ultraviolet LEDs, blue lasers, and ultraviolet lasers, with blue LEDs being preferred. As the blue LED, a nitride-based semiconductor blue LED, which is commonly used in systems that cause yellow phosphors to emit light, can be preferably used.

[0078] As the red phosphor activated with tetravalent manganese ions, a metal fluorine compound activated with tetravalent manganese ions is more preferable, and Mn 4+ Activated Mg fluorogermanate phosphor (2.5MgO·MgF2:Mn 4+ ), M 1 2M 2 F6:Mn 4+ (Each M 1 are each independently one selected from Li, Na, K, Rb, and Cs; M 2 Suitable phosphors include phosphors containing Si, Ge, Sn, Ti, Zr, Nb, and Ta. Specific examples of these include KNaMF6:Mn 4+ (M:Nb or Ta), KRbSiF6:Mn4+ , K2SiF6:Mn 4+ , K2TiF6:Mn 4+ Examples include K2SiF6:Mn, which is generally called KSF 4+ such as M 1 2M 2 F6:Mn 4+ phosphors are preferred.

[0079] In addition to the red phosphor activated by tetravalent manganese ions, the backlight source preferably contains a green phosphor. Examples of the green phosphor include Eu-activated chlorosilicate phosphor, Eu-activated silicate phosphor, Eu-activated β-sialon phosphor, Eu-activated thiogalate phosphor, rare earth aluminate phosphor, lanthanum silicon nitride-based phosphor, etc. The green phosphor may be green quantum dot particles. Among them, from the viewpoint of color reproduction range, Eu-activated β-sialon phosphors such as Si 6-z Al z O z N 8-z :Eu(0 < z < 4.2) or green quantum dot particles are preferred.

[0080] In addition to the red phosphor activated by tetravalent manganese ions, the backlight source may contain a yellow phosphor. Examples of the yellow phosphor include, for example, (Y or Lu)3(Al or Ga)5O 12 :Ce, (Y or Ce)3Al5O 12 such as YAG-based phosphors. Although white light can be emitted only by the combination of a blue LED and a yellow phosphor, the color gamut can be expanded by further combining a red phosphor activated by tetravalent manganese ions. These backlight sources may further include the above green phosphor to adjust the color balance.

[0081] The backlight light source of the present invention is preferably a light source (white LED) that excites a red phosphor activated with tetravalent manganese ions using a blue LED as described above to cause it to emit light, but it may also be a combination of a light source that excites a red phosphor activated with tetravalent manganese ions to emit light and a light source that has another method, such as a combination of the white LED with a sheet containing at least one type of green and red quantum dots, a combination of a blue LED with green quantum dots and a sheet containing a red phosphor activated with tetravalent manganese ions, a combination of a magenta LED in which a red phosphor activated with tetravalent manganese ions is excited and emitted by a blue LED, and a sheet containing green quantum dots, or a combination of the white LED with a white LED that emits yellow phosphors or a white LED with an RGB three-wavelength method. Furthermore, the green quantum dots in the above examples may be replaced with the green phosphors listed above. In the following, the light sources described above may be referred to as KSF light sources.

[0082] The liquid crystal display device may be, for example, a direct type in which the light source is provided directly below the liquid crystal panel, or an edge light type in which the light source is provided on the side and irradiates light via a light guide plate installed below the liquid crystal panel.

[0083] Furthermore, the backlight source is preferably incorporated into the liquid crystal display device as a light source unit by combining a reflector, a diffuser, a prism plate, a lens plate, etc. In order to increase brightness, a reflective polarizing plate may be provided between the backlight source and the liquid crystal panel.

[0084] (polarizing plate) The liquid crystal display device of the present invention is preferably a liquid crystal display device having at least one polarizing plate on each of the backlight light source side (hereinafter, the backlight light source may be simply referred to as the light source) and the viewer side of the liquid crystal cell. That is, the liquid crystal display device of the present invention preferably has a backlight light source, a light source-side polarizing plate, a liquid crystal cell, and a viewer-side polarizing plate. At least one of the light source-side polarizing plate and the viewer-side polarizing plate preferably has a polarizer and at least one polarizer protective film, and usually, a polarizer protective film is laminated on at least one side of the polarizer. (Polarizer protective film) The polarizer protective film preferably has a 45-degree light source compatibility index (FI(45)) calculated by the following formula 1 of 0.4 or more and 0.62 or less. FI(45)=Wd / [Wc / (Rob(45) / Wc)] Equation 1 In Equation 1, Rob(45), Wd, and Wc are as follows: Rob(45): Retardation of the polarizer protective film measured in the in-plane direction of the film at an angle of 45 degrees from the slow axis direction to the fast axis direction, and in a direction tilted by 50 degrees from the normal direction. Wd: The distance between peaks (nm) of the backlight source in the range of 600 to 650 nm Wc: The central wavelength (nm) of the peak group of the backlight light source in the range of 600 to 650 nm

[0085] The 45-degree light source compatibility index (FI(45)) of the polarizer protective film calculated by Equation 1 is preferably 0.4 or more and 0.62 or less when measured at 100 mm intervals along the long side direction and at 100 mm intervals along the short side direction. The values ​​measured at 100 mm intervals along the long side direction and the values ​​measured at 100 mm intervals along the short side direction may be simply referred to as the long side direction and short side direction values.

[0086] The FI(45) of the polarizer protective film is more preferably 0.43 or more, 0.44 or more, 0.445 or more, 0.45 or more, 0.455 or more, and 0.46 or more in this order. The FI(45) of the polarizer protective film is more preferably 0.6 or less, 0.58 or less, 0.57 or less, 0.56 or less, 0.55 or less, and 0.54 or less in that order. The FI(45) values ​​of the polarizer protective film in the long side direction and short side direction are more preferably 0.43 or more, 0.44 or more, 0.445 or more, 0.45 or more, and 0.455 or more and 0.46 or more, in that order. The FI(45) values ​​of the polarizer protective film in the long side direction and short side direction are more preferably 0.60 or less, 0.58 or less, 0.57 or less, 0.56 or less, 0.55 or less, and 0.54 or less, in that order. Incidentally, including the following explanation, the expression "in order of preference" means that the narrower the range of values, the more preferred it is. By setting FI(45) within the above range, even when a high-retardation resin film is used as a polarizer protective film in a liquid crystal display device that uses a light source having a steep emission spectrum such as a KSF light source as a backlight source, color spots, which have previously been considered difficult to suppress, can be effectively suppressed, and images can be natural even when viewed from an oblique direction, and further images with uniform color tone can be obtained even in the corners of the screen. Furthermore, it is preferable that the value obtained by subtracting the minimum value from the maximum value of FI(45) measured at 100 mm intervals along the long side direction and the value obtained by subtracting the minimum value from the maximum value of FI(45) measured at 100 mm intervals along the short side direction are both 0.026 or less, more preferably 0.024 or less, even more preferably 0.021 or less, particularly preferably 0.019 or less, and most preferably 0.016 or less. In addition, the value obtained by subtracting the maximum value from the minimum value measured at 100 mm intervals along the long side direction and the value obtained by subtracting the maximum value from the minimum value measured at 100 mm intervals along the short side direction are sometimes simply referred to as the variation in the long side direction and the variation in the short side direction, respectively. Hereinafter, a polarizer protective film having such FI(45) (in other words, high retardation in the oblique direction) may be referred to as a high Re polarizer protective film or simply as a high Re film.

[0087] Wd is preferably 8 nm or more, more preferably 10 nm or more, and even more preferably 12 nm or more. Wd is preferably 40 nm or less, more preferably 35 nm or less, and even more preferably 30 nm or less.

[0088] Wc is preferably 605 nm or more, more preferably 610 nm or more, and even more preferably 615 nm or more. Wc is preferably 645 nm or less, more preferably 640 nm or less, and even more preferably 635 nm or less.

[0089] Determination of Wd and Wc In the present invention, Wd and Wc are preferably determined by the following method. The emission spectrum of the backlight light source is measured using a spectrophotometer with a measurement wavelength interval in the range of 0.5 to 1 nm. In addition, the light intensity is adjusted using a neutral density filter or the like in accordance with the sensitivity characteristics of the light receiver so that the intensity does not saturate. 1.Selection of the main peak Among the peaks within the range of 600 nm to 650 nm, the peak wavelength and intensity of the peak with the greatest intensity (Pmax) are read. If the intensity difference between adjacent wavelengths is almost the same, the intermediate value between the two points is taken as the peak wavelength, and the larger value is used as the intensity of the peak wavelength. Here, "almost the same intensity difference" means that the intensity difference is 10% or less of the highest peak intensity.

[0090] 2. Selection of secondary peaks Select a peak within the range of 600 nm to 650 nm that has an intensity of 1 / 10 or more of the intensity of Pmax, and read its wavelength and intensity. In this case, if the intensity difference between adjacent wavelengths is approximately the same, proceed as in 1.

[0091] 3. Intensity Correction The intensity value of the peak selected in 2 is multiplied by the spectral sensitivity efficiency value shown in "Table 1 - Determination of spectral luminous efficiency V(λ) in photopic vision" of JIS Z 8785:2019 [ISO 23539:2005 (CIE S 010:2004)], and the resulting value is used as the corrected intensity. Note that since JIS Table 1 is in 1 nm increments, the spectral sensitivity efficiency is the wavelength value of the peak wavelength rounded to the first decimal place.

[0092] 4. Creating peak groups From the secondary peaks selected in step 2, select one peak. This peak will be designated Peak A. If there is a peak (designated Peak B) with a higher corrected intensity than Peak A within 7 nm of Peak A, Peak A will be designated as a secondary peak of Peak B. If there are multiple peaks with higher corrected intensities than Peak A within 7 nm of Peak A, the peak closest to Peak A will be designated Peak B, and Peak A will be designated as a secondary peak of Peak B (if they are equally close, the peak with the higher corrected intensity will be designated Peak B, and Peak A will be designated as a secondary peak of Peak B). If the secondary peak (Peak B above) is a secondary peak of another peak (designated Peak C), they will be combined (i.e., both Peak A and Peak B) and designated as secondary peaks of Peak C. If there is no peak with a higher corrected intensity than Peak A within 7 nm of Peak A, Peak A will be designated as an independent peak. The main peak is also designated as an independent peak. All secondary peaks are classified as independent peaks or secondary peaks, and an independent peak and its secondary peaks will be designated as a peak group. If there are no secondary peaks, even an independent peak alone will be designated as a peak group.

[0093] 5. Determining Peak Intensities The corrected intensities of each peak (independent peak or associated peak) in the peak group determined in 4 are summed up, and the sum is taken as the peak group intensity.

[0094] 6. Determining the peak wavelength of the peak group The sum of the values ​​obtained by multiplying the peak wavelength of each peak (independent peak or associated peak) in the peak group by the corrected intensity is divided by the sum of the individual peak intensities, and the resulting value is used as the peak wavelength of the peak group. The peak wavelength can be set to a value rounded to two decimal places.

[0095] 7. Determination of the distance between peak groups (Wd) The two peak groups with the greatest peak group intensities are selected, with the one with the greater peak group intensity designated as the first peak group and the one with the lesser peak group intensity designated as the second peak group. The difference between the peak wavelengths of the first peak group and the second peak group is calculated to one decimal place to determine the distance between the peak groups.

[0096] 8. Determining the central wavelength (Wc) The average value of the peak wavelengths of the first peak group and the second peak group is calculated to one decimal place and used as the center wavelength.

[0097] For example, the case of the KSF light source shown in FIG. 1 will be specifically described. For the peak with the greatest intensity (Pmax), the intensity was measured as 1.000 at a wavelength of 630.5 nm, and the intensity was measured as 0.916 at the adjacent wavelength of 631.2 nm. Therefore, the peak wavelength of the main peak is (630.5 + 631.2) / 2 = 630.85, which is rounded to two decimal places to 630.9 nm, and the intensity is 1.000. A minor peak having an intensity of 1 / 10 or more of the intensity of Pmax is Sub-peak 1: Peak wavelength 608.6 nm (intensity 0.158), which is the intermediate value between the peak wavelength 608.2 nm (intensity 0.153) and the peak wavelength 608.9 nm (intensity 0.158), Sub-peak 2: Peak wavelength 613.4 nm (intensity 0.368), Sub-peak 3: Peak wavelength 634.9 nm (intensity 0.698), Sub-peak 4: Peak wavelength 647.5 nm (intensity 0.195) is.

[0098] By multiplying each by the spectral sensitivity efficiency specified in JIS, the corrected intensity is calculated as follows: Sub-peak 1: Peak wavelength 608.6 nm (corrected intensity: 0.158 × 0.515 = 0.081), Sub-peak 2: Peak wavelength 613.4 nm (corrected intensity: 0.368 × 0.465 = 0.171) Main peak: Peak wavelength 630.9 nm (corrected intensity: 1.000 x 0.244 = 0.244) Minor peak 3: Peak wavelength 634.9 nm (corrected intensity: 0.698 × 0.217 = 0.151) Sub-peak 4: Peak wavelength 647.5 nm (corrected intensity: 0.195 × 0.118 = 0.023)

[0099] Sub-peak 3 with a peak wavelength of 634.9 nm can be considered an accompanying peak of the main peak with a peak wavelength of 630.9 nm, and these two peaks form the first peak group, with a peak group intensity of 0.395. Sub-peak 1 with a peak wavelength of 608.6 nm can be considered an accompanying peak of sub-peak 2 with a peak wavelength of 613.4 nm, and these two peaks form the second peak group, with a peak group intensity of 0.252. Sub-peak 4 with a peak wavelength of 647.5 nm is an independent peak (a peak group on its own), with a peak group intensity of 0.023.

[0100] The peak wavelength of the first peak group is (630.9×0.244+624.9×0.151) / (0.244+0.151)=611.86nm This becomes: The peak wavelength of the second peak group is (608.6×0.081+613.4×0.171) / (0.081+0.171)=632.43nm This becomes: The distance between peak groups (Wd) is 20.6 nm, and the central wavelength (Wc) is 622.1 nm.

[0101] From these results, in the case of a light source using a manganese ion-activated metal fluorine compound, such as KSF, as a red phosphor, the Rob(45) of the polarizer protective film is preferably 7,500 nm or more, and more preferably 8,100 nm or more, 8,280 nm or more, 8,380 nm or more, 8,470 nm or more, and 8,650 nm or more in that order. Also, the Rob(45) is preferably 11,700 nm or less, and more preferably 11,300 nm or less, 10,900 nm or less, 10,720 nm or less, 10,530 nm or less, 10,340 nm or less, and 10,160 nm or less in that order.

[0102] In the case of a light source using a manganese ion-activated metal fluorine compound, such as KSF, as the red phosphor, the Rob(45) values ​​of the polarizer protective film in the long and short side directions are preferably 7,500 nm or more, and more preferably 8,100 nm or more, 8,280 nm or more, 8,380 nm or more, 8,470 nm or more, and 8,650 nm or more in this order. The Rob(45) values ​​of the polarizer protective film in the long and short side directions are preferably 11,700 nm or less, and more preferably 11,300 nm or less, 10,900 nm or less, 10,720 nm or less, 10,530 nm or less, 10,340 nm or less, and 10,160 nm or less in this order. The fluctuations of Rob(45) of the polarizer protective film in the long and short side directions are preferably 500 nm or less, more preferably 450 nm or less, even more preferably 400 nm or less, particularly preferably 350 nm or less, and most preferably 300 nm or less.

[0103] Although the above describes the case of a backlight light source for a liquid crystal display device, the 45-degree light source compatibility index (FI(45)) can be calculated in the same way for light incident on a polarizing plate of an image display device. For example, in the case of a backlight source for a liquid crystal display device, the light spectrum can be measured by removing the backlight unit and emitting white light. For example, in the case of light incident on a polarizing plate in an organic EL image display device, the polarizing plate on the viewing side of the organic EL cell can be removed from the organic EL image display device and the image display device can be made to emit white light. If the components between the backlight source and the outermost surface of the image display device, or between the image display cell such as the organic EL cell and the outermost surface of the image display device, have uniform transmission characteristics in the 600 to 650 nm range, the spectrum of light emitted from the image display device can be used as a substitute. The same applies to the 30-degree illuminant compatibility index (FI(30)) and the 60-degree illuminant compatibility index (FI(60)) described below.

[0104] According to the inventors' investigations, the reason why color spots seen from an oblique direction can be suppressed within such a specific retardation range is thought to be as follows, but the present invention is not limited to this reason. First, the reason why color spots occur is thought to be as follows. When a high Re polarizer protective film is used, polarization selectivity of reflectance occurs not only in the polarizer or reflective polarizer, but also in the interface reflection between the high Re polarizer protective film and air or other layers, so the high Re polarizer protective film acts as a weak polarizer, and is, so to speak, sandwiched between polarizers. When the polarizing plate is viewed from the front, the interface hardly acts as a polarizer, but the greater the angle at which the polarizing plate is viewed from the normal direction, the greater the polarizing effect becomes, reaching a maximum near the Brewster angle.

[0105] In polarizing plates, the polarizer's absorption axis is often aligned with the in-plane fast axis of the high Re film. In this case, even if the viewing angle is changed from the front to an angle along the slow axis of the high Re film, the retardation of the high Re film decreases, but because the vibration direction of the polarized light is perpendicular to the fast axis of the high Re film, the linearly polarized light is not disturbed by the high Re film and no color spots occur. Similarly, even if the viewing angle is changed to an angle along the fast axis of the resin film, the retardation of the high Re film increases, but because the vibration direction of the polarized light is parallel to the slow axis of the resin film, the linearly polarized light is not disturbed by the high Re film and no color spots occur.

[0106] However, when the viewing angle is changed from the front to a direction that is angled in the film plane with respect to the slow axis of the high Re film toward the fast axis, the shape of the refractive index ellipsoid of the high Re film viewed from the oblique direction also changes as the viewing angle changes, and the slow axis and fast axis become misaligned with the vibration direction of the polarized light. As a result, the linearly polarized light that enters the high Re film obliquely becomes elliptically polarized light, and the transmittance changes depending on the state of elliptically polarized light due to the action of the polarizer (or the action of the interface polarizer) when it exits the high Re film. Hereinafter, the angle of the fast axis relative to the slow axis in the film plane will be referred to as the azimuthal angle, and the angle relative to the normal to the film will be referred to as the polar angle. Furthermore, when simply referring to an oblique direction, it may refer to a direction with a polar angle regardless of the azimuthal angle.

[0107] Transmittance depends on wavelength and retardation, as shown in Equation 4 below. When the light source has a continuous, gentle emission spectrum, such as an LED using a yellow phosphor, the spectral envelope (the envelope of the intensity of the light transmitted by the polarizer (or its function as a polarizer) of the elliptically polarized component that passed through the resin film) multiplied by the transmittance at each wavelength resembles the spectral shape of the original light source. However, when the emission spectrum has a steep peak, such as that of a KSF light source, it becomes difficult for this envelope to reproduce the spectral shape of the original light source. When viewing an image, the azimuthal and polar angles differ between the front and back of the image, and the left and right sides. The retardation changes with angle, changing the polarization state of light passing through the high-Resolution film. This results in angles that transmit and block the steep peak, resulting in color spots.

[0108] T=cos 2 α-sin2βsin2(β-α)sin 2 (πRe / λ) (Equation 4) α: the angle between the absorption axes of the two polarizing plates β: Angle between the absorption axis of the polarizer and the slow axis of the birefringent material λ: Wavelength T: Transmittance

[0109] According to Equation 4, when the retardation is in the range of several thousand to tens of thousands of nanometers, the transmittance T will repeat between 0% and 100% at wavelengths ranging from several nanometers to several tens of nanometers. As shown in Figure 1, a KSF light source has a main peak group near 630 nm and a sub-peak group near 610 nm. If the period of the transmittance T is such that one of the main peak group or the sub-peak group has a high transmittance and the other has a low transmittance, then either the main peak group or the sub-peak group will always be transmitted, and the amount of change in red light to the human eye will be small, making it less likely to be perceived as color mottling.

[0110] As mentioned above, color spots become noticeable at azimuth angles of about 30 to 60 degrees and angles from the normal direction exceeding 45 degrees. However, if the retardation in the oblique direction in this region of the high Re polarizer protective film is within an appropriate range, color spots can be suppressed.

[0111] As mentioned above, when a birefringent film is tilted from the front direction (normal direction) toward the slow axis, the retardation in the oblique direction of the film becomes smaller than the in-plane retardation, and when it is tilted toward the fast axis, it becomes larger. When the film is tilted at an azimuthal angle toward the fast axis, the retardation becomes intermediate depending on the degree of the azimuthal angle. It is believed that color spots can be effectively suppressed by setting the retardation from an oblique direction in a region where color spots are likely to occur within a preferred range.

[0112] The 30-degree light source compatibility index (FI(30)) calculated by the following formula 2 and / or the 60-degree light source compatibility index (FI(60)) calculated by the following formula 3 of the polarizer protective film used in the present invention is preferably 0.35 or more and 0.68 or less. FI(30)=Wd / [Wc / (Rob(30) / Wc)] Equation 2 FI(60)=Wd / [Wc / (Rob(60) / Wc)] Equation 3 In Equation 2 and Equation 3, Rob(30) and Rob(60) are as follows, and Wd and Wc are as defined above. Rob(30): Retardation of the polarizer protective film measured at an angle of 30 degrees from the slow axis direction to the fast axis direction in the in-plane direction of the film, and in a direction tilted by 50 degrees from the normal direction Rob(60): Retardation of the polarizer protective film measured at an angle of 60 degrees from the slow axis direction to the fast axis direction in the in-plane direction of the film, and in a direction tilted by 50 degrees from the normal direction

[0113] The 30-degree light source compatibility index (FI(30)) in the long side direction and the short side direction of the polarizer protective film used in the present invention and / or the 60-degree light source compatibility index (FI(60)) in the long side direction and the short side direction of the polarizer protective film used in the present invention are preferably 0.35 or more and 0.68 or less.

[0114] The FI(30) and / or FI(60) of the polarizer protective film are more preferably 0.37 or more, 0.38 or more, 0.39 or more, and 0.4 or more, in that order. FI(30) and / or FI(60) are preferably less than FI(45). The FI(30) and / or FI(60) of the polarizer protective film is more preferably 0.65 or less, 0.63 or less, 0.62 or less, 0.61 or less, and 0.6 or less, in that order. FI(30) and / or FI(60) preferably exceed FI(45). The FI(30) and / or FI(60) values ​​of the polarizer protective film in the long side direction and short side direction are preferably 0.37 or more, 0.38 or more, 0.39 or more, and 0.4 or more, in this order, and are preferably less than the FI(45) values ​​in the long side direction and short side direction. The FI(30) and / or FI(60) values ​​of the polarizer protective film in the long side direction and short side direction are preferably 0.65 or less, 0.63 or less, 0.62 or less, 0.61 or less, and 0.6 or less, in this order, and preferably exceed the FI(45) values ​​in the long side direction and short side direction. By setting FI(30) and FI(60) within the above ranges, color spots can be effectively suppressed over a wide range of areas where color spots are likely to occur.

[0115] In the case of a light source using a manganese ion-activated metal fluorine compound, such as KSF, as the red phosphor, the Rob(30) and / or Rob(60) of the polarizer protective film are preferably 6570 nm or more or 6600 nm or more. Rob(30) is more preferably 6960 nm or more, 7150 nm or more, 7340 nm or more, and 7530 nm or more, in that order. It is preferable that Rob(30) and / or Rob(60) are less than Rob(45). It is preferable that Rob(30) and / or Rob(60) of the polarizer protective film are 12200 nm or less. It is more preferable that Rob(30) and / or Rob(60) are 11900 nm or less, 11700 nm or less, 11500 nm or less, and 11300 nm or less, in that order. It is preferable that Rob(30) and / or Rob(60) exceed Rob(45).

[0116] In the case of a light source using a manganese ion-activated metal fluorine compound, such as KSF, as the red phosphor, the Rob(30) and / or Rob(60) values ​​of the polarizer protective film in the long and short direction are preferably 6,600 nm or more. The Rob(30) and / or Rob(60) values ​​in the long and short direction are more preferably 6,960 nm or more, 7,150 nm or more, 7,340 nm or more, and 7,530 nm or more, in that order. The Rob(30) and / or Rob(60) values ​​in the long and short direction are preferably less than the Rob(45) values ​​in the long and short direction. The Rob(30) and / or Rob(60) values ​​in the long and short direction of the polarizer protective film are preferably 12,200 nm or less. The values ​​of Rob(30) and / or Rob(60) in the long side direction and short side direction are more preferably 11,900 nm or less, 11,700 nm or less, 11,500 nm or less, and 11,300 nm or less, in that order. Note that the values ​​of Rob(30) and / or Rob(60) in the long side direction and short side direction are preferably greater than the values ​​of Rob(45) in the long side direction and short side direction.

[0117] The ratio (ΔFI / FI(45)) of the difference between FI(30) and FI(60) (ΔFI=FI(60)−FI(30)) to FI(45) of the polarizer protective film is preferably 0.2 or more and 0.35 or less. The value of ΔFI / FI(45) in the long side direction and the short side direction of the polarizer protective film is preferably 0.2 or more and 0.35 or less. ΔFI / FI(45) is more preferably 0.22 or more, 0.23 or more, 0.24 or more, and 0.25 or more, in that order. ΔFI / FI(45) is more preferably 0.34 or less, 0.33 or less, 0.32 or less, and 0.31 or less, in that order. The values ​​of ΔFI / FI(45) in the long side direction and short side direction are more preferably 0.22 or more, 0.23 or more, 0.24 or more, and 0.25 or more, in that order. The values ​​of ΔFI / FI(45) in the long side direction and short side direction are more preferably 0.34 or less, 0.33 or less, 0.32 or less, and 0.31 or less, in that order. By setting ΔFI / FI(45) at the above range or higher, color spots can be effectively suppressed over a wide range where color spots are likely to occur. Furthermore, the entire screen can be made to have a uniform color tone. ΔFI / FI(45) can be increased by increasing the uniaxiality of the polarizer protective film, but from the viewpoints of ease of tearing along the slow axis direction in the film plane, handleability, etc., it is preferable that the value be the above range or lower.

[0118] In the case of a light source using a manganese ion-activated metal fluorine compound, such as KSF, as the red phosphor, the difference between Rob(30) and Rob(60) of the polarizer protective film (ΔRob=Rob(60)-Rob(30)) is preferably 1880 nm or more or 1900 nm or more, and more preferably 2000 nm or more, 2100 nm or more, 2200 nm or more, and 2250 nm or more in this order. ΔRob of the polarizer protective film is preferably 3400 nm or less or 3380 nm or less, and more preferably 3300 nm, 3200 nm or less, 3100 nm or less, 3000 nm or less, and 2900 nm or less in this order. In the case of a light source using a manganese ion-activated metal fluorine compound, typically KSF, as the red phosphor, the ΔRob values ​​of the polarizer protective film in the long and short side directions are preferably 1900 nm or more, and more preferably 2000 nm or more, 2100 nm or more, 2200 nm or more, and 2250 nm or more in this order. The ΔRob values ​​of the polarizer protective film in the long and short side directions are preferably 3400 nm or less, and more preferably 3300 nm, 3200 nm or less, 3100 nm or less, 3000 nm or less, and 2900 nm or less in this order. The preferred range of ΔRob / Rob(45) is the same as the range of ΔFI / FI(45).

[0119] The surface roughness (SRa) (JIS B0601:1994) of the high Re polarizer protective film is preferably 0.05 μm or less, more preferably 0.01 μm or less, and even more preferably 0.005 μm or less on at least one side, and even more preferably on both sides. By setting the SRa to 0.05 μm or less, a highly transparent film can be obtained. Furthermore, to ensure the slipperiness of the film, the SRa is preferably 0.0001 μm or more, and even more preferably 0.0005 μm or more.

[0120] The ten-point average surface roughness (SRz) (JIS B0601:1994) of at least one surface, and more preferably both surfaces, of the high Re polarizer protective film is preferably 1.0 μm or less, more preferably 0.70 μm or less, even more preferably 0.50 μm or less, particularly preferably 0.30 μm or less, and most preferably 0.2 μm or less. SRz is preferably 0.001 μm or more, and more preferably 0.005 μm or more.

[0121] The SRa and SRz of the light source side of the light source-side polarizing plate (the side opposite the liquid crystal cell) are preferably within the above ranges. The phenomenon of increased surface roughness is often caused by coarse particles such as particle aggregates and catalyst residues. By keeping the SRa and SRz below the above upper limit, scratches on the film surface caused by coarse particles falling off during the film manufacturing and processing steps or after the film is incorporated into a liquid crystal display device can be prevented, and this can prevent bright spots and dark spots that degrade image quality. Furthermore, a decrease in image clarity and contrast can also be prevented. Coarse particles in the film are preferably removed by a filter during the production of the resin, or by providing a filter in the film production line. Furthermore, when the surface is an easy-adhesion layer or other coating layer, it is preferable to employ a method such as filtering the coating solution after preparation, or filtering the coating solution by providing a filter in the line that sends the coating solution to the coating die.

[0122] The number of foreign particles with a major axis of 100 μm or more in the high Re polarizer protective film is preferably two or less. Foreign particles with a major axis of 100 μm or more in the high Re polarizer protective film are those observed as bright spots with a major axis of 100 μm or more when a polarizer cut to a size suitable for incorporation into an image display device is placed in a crossed Nicol configuration on the high Re polarizer protective film side of the polarizer. Examples of foreign particles in the film include aggregates of lubricant particles. It is preferable not only to remove aggregates with a small pore filter during film formation, but also to form a multilayer film with lubricant particles only in the surface layer. It is also preferable to use lubricant particles not in the film but in an easy-adhesion coating on the surface.

[0123] Furthermore, resin degradation products can also become contaminants in the film. While hard contaminants in the molten resin can be removed using the aforementioned filter, gel-like contaminants formed by thermal degradation of the molten resin can deform to some extent at the temperature of the molten resin and may slip through the filter even if they are larger than the filter's pore size. Larger contaminants may be cut off by the filter, increasing the number of contaminants. Furthermore, thermal degradation products of the resin generated in the line downstream of the filter are directly incorporated into the film. Not only do these contaminants fail to follow the stretching orientation of the surrounding resin during the stretching process, but they also disrupt the stretching orientation of the surrounding resin, appearing as bright spots when measured with a crossed Nicol filter. Even small, hard contaminants that pass through the filter can create voids between the resin and the film during stretching, potentially becoming contaminants. Furthermore, the filter's pore size does not necessarily mean that contaminants larger than the pore size will pass through; even contaminants larger than the pore size will still pass through to a certain extent. The number of foreign particles having a major axis of 100 μm or more in the high Re polarizer protective film is more preferably 1 or less, and is preferably 0, that is, none.

[0124] The number of foreign particles having a major axis of 50 μm or more in the high Re polarizer protective film is preferably 5 or less, more preferably 3 or less, even more preferably 1 or less, and particularly preferably 0. Furthermore, the number of foreign particles with a major axis of 20 μm or more in the high Re polarizer protective film is preferably 10 or less, more preferably 5 or less, even more preferably 3 or less, particularly preferably 1 or less, and most preferably 0.

[0125] If such foreign matter is present in a high Re polarizer protective film, not only will it be visible if it is colored when the image is viewed closely, but even if it is nearly colorless and transparent, it may have a different refractive index from the surrounding normal areas, resulting in a small area appearing as a different color or disrupting the uniformity of the color tone. Furthermore, in the case of a polarizing plate on the light source side, it may appear as a dark spot.

[0126] In order to reduce the amount of foreign matter in the film, it is preferable to minimize the areas where the molten resin stagnates along the path through which it passes. Specifically, in an extruder, it is preferable to minimize the steps between screw elements, between barrel blocks, and at the connecting portions of piping. It is also preferable to design piping, filter housings, filter elements, and nozzle flow paths to minimize the stagnation of resin, or to reduce the roughness of the inner walls of these structures.

[0127] Furthermore, the amount of foreign matter tends to increase when the film production starts or when the resin extrusion rate is increased. In these cases, it is preferable to temporarily increase the resin extrusion rate and then decrease it to the specified amount.

[0128] Furthermore, it is preferable to inspect the film for defects after production so that films with a large amount of foreign matter are not used for the production of polarizing plates, and to mark defective areas so that polarizing plates with those areas are not used.

[0129] The haze of the high Re polarizer protective film is preferably 5% or less, more preferably 3% or less, even more preferably 2% or less, and particularly preferably 1.5% or less. The lower limit of the haze is preferably 0.01% or more, and even more preferably 0.1% or more. Note that SRa and SRz are the SRa and SRz of the surface of the original high Re polarizer protective film before coating with a functional layer such as a low-reflection layer, which will be described later. However, if an easy-adhesion layer is provided in-line, the values ​​are those of the easy-adhesion layer surface. The same applies to haze. The haze can be measured using a turbidity meter (NHD2000, manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS-K7105.

[0130] The resin used in the high Re polarizer protective film is not particularly limited as long as it generates birefringence upon orientation. However, polyester, polycarbonate, polystyrene, etc. are preferred, especially polyester, because they can increase retardation and have low moisture permeability and moisture absorption. Preferred polyesters include polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polytetramethylene terephthalate (PBT), and polyethylene naphthalate (PEN), with PET and PEN being preferred. These polyesters may be copolymerized with carboxylic acid components and / or glycol components other than the main components. When the total amount of the carboxylic acid components and / or glycol components is taken as 100 mol%, the total amount of the carboxylic acid components and / or glycol components other than the main components is preferably 10 mol% or less, more preferably 5 mol% or less, even more preferably 2 mol% or less, particularly preferably 1.5 mol% or less, and most preferably 1.2 mol% or less. A content of less than the above range can improve heat resistance and reduce heat shrinkage. The glycol components other than the main components also include by-products such as diethylene glycol. In addition, since side reactions such as glycol dimerization cannot be completely avoided in polyester polymerization, the amount of glycol components other than the main constituent components is preferably 0.1 mol % or more, and the most preferred range of the amount of glycol components other than the main constituent components is 0.2 to 1 mol %. The above polyesters are easy to stretch at high magnifications and have impact resistance, making them easy to handle. In addition, their low moisture permeability and moisture absorption reduce warping of liquid crystal cells due to environmental changes. Therefore, polyester high Re polarizer protective films are suitable for use in large liquid crystal display devices such as 45-inch or larger (screen diagonal length of 45 inches), 50-inch or larger (screen diagonal length of 50 inches), 55-inch or larger (screen diagonal length of 55 inches), and 60-inch or larger (screen diagonal length of 60 inches).

[0131] The thickness of the high Re polarizer protective film is preferably 25 to 120 μm, but because retardation is the product of the in-plane refractive index and thickness of the film, the appropriate thickness range varies depending on the resin, stretching ratio, etc. For example, for polyethylene terephthalate, the thickness is preferably 60 μm or more, and more preferably 63 μm or more, 65 μm or more, 70 μm or more, 73 μm or more, and 75 μm or more in that order. The thickness is also preferably 100 μm or less, and more preferably 95 μm or less, 90 μm or less, 87 μm or less, 85 μm or less, and 83 μm or less in that order. A thickness of less than the above range is suitable for thinning image display devices. In the case of polyethylene naphthalate, the thickness is preferably 25 μm or more, more preferably 30 μm or more, 35 μm or more, and 37 μm or more in that order, and is preferably 60 μm or less, more preferably 55 μm or less, 50 μm or less, and 47 μm or less in that order. The upper and lower limits are combined to form a thick range when the stretching ratio is low, and a thin range when the stretching ratio is high. The thickness variation of the high Re polarizer protective film in both the MD and TD directions is preferably 6% or less, more preferably 5% or less, still more preferably 4% or less, and particularly preferably 3% or less.

[0132] The intrinsic viscosity (IV) of the resin constituting the film is preferably 0.45 to 1.5 dL / g. In the case of PET, the IV is preferably 0.5 to 1.5 dL / g. The lower limit of the IV is more preferably 0.53 dL / g, and even more preferably 0.55 dL / g. The upper limit of the IV is more preferably 1.2 dL / g, and even more preferably 1 dL / g, and particularly preferably 0.8 dL / g. For PEN, the lower limit of IV is preferably 0.45 dL / g, more preferably 0.48 dL / g, even more preferably 0.5 dL / g, and particularly preferably 0.53 dL / g. The upper limit of IV is more preferably 1 dL / g, more preferably 0.8 dL / g, even more preferably 0.75 dL / g, and particularly preferably 0.7 dL / g. By setting the thickness within the above range, a film having excellent mechanical strength such as impact resistance can be obtained, and the film can be produced efficiently without placing a large load on the equipment.

[0133] In the polarizer protective film, the amount of antimony atoms in the residue insoluble in a mixed solvent of parachlorophenol and tetrachloroethane is preferably 50 mg or less, more preferably 30 mg or less, even more preferably 20 mg or less, particularly preferably 10 mg or less, and most preferably 5 mg or less per 1 kg of the resin constituting the film. The amount of antimony atoms in the residue is preferably as small as possible, but the lower limit is preferably 0.1 mg, more preferably more than 0.5 mg, and even more preferably more than 1 mg. The polarizer protective film is preferably formed from a resin polymerized using an antimony compound as a catalyst, particularly a polyester resin. Examples of antimony compounds used as catalysts include antimony trioxide, antimony pentoxide, antimony acetate, and antimony glycooxide, with antimony trioxide (Sb2O3) being preferred. As the catalyst, in addition to the antimony compound, a titanium compound catalyst such as tetrabutoxy titanate, or an aluminum catalyst such as basic aluminum acetate and a hindered phenol-containing phosphate ester (for example, Irganox 1222) may be used in combination. Furthermore, it is also preferable to add a polymerization stabilizer or auxiliary, or a melt resistivity adjuster, typical examples of which include phosphorus compounds such as trimethyl phosphate and phosphoric acid, magnesium compounds such as magnesium acetate, and calcium compounds such as calcium acetate.

[0134] In order to keep the amount of antimony atoms in the residue insoluble in the mixed solvent of the film at or below the above level, it is preferable to keep the amount of antimony atoms in the residue insoluble in the mixed solvent of the resin used in producing the film at or below the above level. As a method for reducing the amount of antimony atoms in the residue insoluble in the mixed solvent of the polyester resin to the above-mentioned level or less, for example, the following methods can be mentioned, and these methods can be used alone or in combination. The amount of antimony added to the polyester resin after polymerization is preferably 300 ppm or less, more preferably 250 ppm or less, even more preferably 220 ppm or less, and particularly preferably 200 ppm or less, in terms of antimony atomic weight. The lower limit of the antimony amount is preferably 30 ppm, even more preferably 50 ppm, and particularly preferably 80 ppm. The antimony compound is added as a solution or slurry in ethylene glycol, with the concentration of the antimony compound being preferably 10% by mass or less, more preferably 7% by mass or less, and particularly preferably 5% by mass or less. The maximum temperature for polymerization of the polyester resin is preferably 290°C or less, and more preferably 285°C or less. Increase the degree of pressure reduction so that the time during which the polyester resin reaches its maximum polymerization temperature is within 45 minutes, or even 30 minutes. In the case of continuous polymerization, this is the average residence time. When a phosphorus compound, magnesium compound, or calcium compound is added, the amount added is preferably 15 to 120 ppm, more preferably 20 to 100 ppm, and even more preferably 25 to 80 ppm in terms of phosphorus atomic weight relative to the polyester resin after polymerization, and the magnesium atomic weight or calcium atomic weight is preferably 30 to 120 ppm, more preferably 40 to 100 ppm.Furthermore, it is preferable to add the phosphorus compound after adding the magnesium compound or calcium compound, and in this case, to add it in multiple divided stages.

[0135] The high Re polarizer protective film desirably has a light transmittance of 20% or less at a wavelength of 380 nm. The light transmittance at a wavelength of 380 nm is more preferably 15% or less, even more preferably 10% or less, and particularly preferably 5% or less. If the light transmittance is 20% or less, deterioration of iodine and dichroic dyes in the polarizing layer due to ultraviolet rays can be suppressed. The transmittance is measured in a direction perpendicular to the plane of the film and can be measured using a spectrophotometer (for example, Hitachi U-3500 model).

[0136] The light transmittance of the high Re polarizer protective film at a wavelength of 380 nm can be reduced to 20% or less by adding an ultraviolet absorber to the film, applying a coating solution containing an ultraviolet absorber to the film surface, or by appropriately adjusting the type and concentration of the ultraviolet absorber and the film thickness. The ultraviolet absorber is a known substance. Examples of the ultraviolet absorber include organic and inorganic ultraviolet absorbers, with organic ultraviolet absorbers being preferred from the viewpoint of transparency.

[0137] Examples of organic ultraviolet absorbers include benzotriazoles, benzophenones, cyclic iminoesters, and combinations thereof, but there are no particular limitations as long as the absorbance is within the desired range.

[0138] To improve the slipperiness of the high Re polarizer protective film, it is also preferable to add particles having an average particle size of 0.05 to 2 μm. Examples of the particles include inorganic particles such as titanium oxide, barium sulfate, calcium carbonate, calcium sulfate, silica, alumina, talc, kaolin, clay, calcium phosphate, mica, hectorite, zirconia, tungsten oxide, lithium fluoride, and calcium fluoride, and organic polymer particles such as styrene-based, acrylic-based, melamine-based, benzoguanamine-based, and silicone-based particles. These particles may be added to the entire film, or may be added only to the skin layer of a coextruded multilayer film having a skin-core structure. It is also preferable that the film itself does not contain particles, but that the particles are added to the easy-adhesion layer described below. When particles are added to a film resin, methods include using a raw resin manufactured with particles added in advance, and using a masterbatch to which particles are added at a high concentration during film production. In either method, if the amount of particle agglomerates increases, image clarity and contrast may decrease, or the surface roughness may increase, causing particles to fall off. It is preferable to remove these particle agglomerates using a filter or the like during the production of the raw resin or masterbatch. Furthermore, it is preferable to install a filter in the molten resin line during film production to remove particle agglomerates. The filters used for these purposes preferably have a 95% separation particle size of 50 μm or less, more preferably 20 μm or less, particularly preferably 10 μm or less, and most preferably 5 μm or less. Polymerization catalysts for resins (especially polyester resins) include antimony compounds such as antimony trioxide, titanium compounds such as tetrabutyl titanate, and mixed catalysts of aluminum compounds such as basic aluminum acetate with esters of 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid or their salts, such as Irganox 1222 and Irganox 1425. However, even these catalyst residues can cause haze degradation and surface roughness. It is preferable to use resins produced by selecting the catalyst amount and polymerization conditions that minimize residue generation, depending on the catalyst. Furthermore, it is preferable to install a filter with the above-mentioned pore size in the line for molten resin during film production. Preferred examples of filters include sintered metal, sintered metal wire, metal mesh, and ceramic.

[0139] The high Re polarizer protective film can be obtained according to a general film manufacturing method. The following describes a case where the film is a polyester film. Hereinafter, in the description of the manufacturing method, the high Re polarizer protective film may be referred to as a polyester film. For example, a method for producing a polyester film includes melting a polyester resin (e.g., PET), extruding the non-oriented polyester into a sheet, stretching the non-oriented polyester in the longitudinal and transverse directions at a temperature above the glass transition temperature, and then subjecting the non-oriented polyester to a heat treatment.

[0140] The polarizer protective film may be uniaxially stretched or biaxially stretched, but as the biaxiality becomes stronger, a greater thickness is required to ensure the required Rob(45). Although Rob(45) can be kept within an appropriate range by adjusting the thickness, uniaxial stretching is preferred for reasons such as making it easier to keep Rob(30) and Rob(60) within appropriate ranges and to keep ΔFI / FI(45) within appropriate ranges. Furthermore, even if the film is biaxially stretched, high uniaxiality is preferred.

[0141] The main orientation axis of the polarizer protective film may be the running direction of the film (also referred to as the longitudinal direction or MD direction) or the direction perpendicular to the longitudinal direction (also referred to as the orthogonal direction or TD direction). In the case of MD stretching, roll stretching is preferred, and in the case of TD stretching, tenter stretching is preferred. TD stretching using a tenter is a preferred method in terms of minimizing scratches on the film surface, productivity, and bonding to a polarizer made of stretched PVA.

[0142] In stretching, the unstretched film is preheated and stretched preferably at 80 to 130°C, more preferably 90 to 120°C. The stretching ratio in the main stretching direction is preferably 3.6 to 7 times, more preferably 3.8 to 6.5 times, even more preferably 4 to 6.2 times, and particularly preferably 4.1 to 6 times. A lower stretching temperature and a higher stretching ratio tend to increase Rob(45) and decrease ΔFI / FI(45). To further enhance uniaxiality, it is also preferable to shrink the film in a direction perpendicular to the stretching direction during stretching. In the case of TD stretching using a tenter, shrinkage can be achieved, for example, by narrowing the tenter clip spacing. The shrinkage treatment is preferably 1 to 20%, more preferably 2 to 15%.

[0143] In the case of biaxial stretching, in order to keep Rob(45), Rob(30), Rob(60), and ΔFI / FI(45) in the appropriate ranges, the above is used as the main stretching, and before the main stretching, the film is stretched in the direction perpendicular to the main stretching by 1.2 times or less, more preferably 1.15 times or less, and particularly preferably 1.13 times or less. The lower limit of the stretching ratio in the perpendicular direction is preferably 1.01 times, more preferably 1.03 times, and particularly preferably 1.05 times.

[0144] It is preferable to perform heat setting after stretching. The heat setting temperature is preferably 150 to 230°C, more preferably 170 to 220°C. A lower heat setting temperature tends to increase Rob(45) and decrease ΔFI / FI(45). However, a low heat setting temperature tends to increase the thermal shrinkage of the film. In the heat setting, it is also preferable to perform a relaxation treatment in the main stretching direction or in a direction perpendicular thereto. The relaxation treatment is preferably 0.5 to 10%, more preferably 1 to 5%.

[0145] The heat-set film is cooled and then wound up. It is also preferable to perform additional slight stretching in the main stretching direction during the cooling process in order to impart an appropriate heat shrinkage force and reduce warpage of the liquid crystal panel after assembly. The additional slight stretching is preferably performed at a film temperature of 80 to 150°C, and the stretching ratio is preferably 1 to 5%, more preferably 1.5 to 3%. In order to adjust the thermal shrinkage rate, the film may be subjected to an annealing treatment after film formation.

[0146] The high Re polarizer protective film may be subjected to treatments such as corona treatment, flame treatment, and plasma treatment to improve adhesion.

[0147] Since the retardation in an oblique direction is affected by the thickness of the film, it is preferable to reduce unevenness in the thickness of the film. In order to reduce thickness unevenness in the TD of the film, it is preferable to adopt methods such as precisely controlling the spacing between the tips of the die when extruding the molten resin into a sheet, optimizing the flow path inside the die so that the resin is extruded uniformly in the width direction from the tips of the die, reducing the temperature difference in the width direction at the tips of the die, etc. It is also preferable to measure the thickness of the film in the TD and use a control program that feeds back the results to the spacing between the tips of the die so that it varies gradually. To reduce thickness unevenness in the MD direction of the film, it is preferable to stabilize the contact point of the extruded resin with the chill roll by suppressing pulsation of the extruded resin, increasing the vibration-proofing properties of the casting equipment such as the die and chill roll, reducing fluctuations in the air pressure used for pinning, or reducing the vibration of the electrodes in the case of electrostatic application. It is preferable to take these measures in combination.

[0148] Furthermore, temperature fluctuations during tenter stretching can cause fluctuations in the film's orientation, affecting retardation in the diagonal direction. Temperature differences are particularly likely to occur near the clip due to the clip temperature. Furthermore, bowing can also cause differences in the force acting on the film. These influences are thought to result in differences in the optical properties of the film in the TD direction. Taking these factors into consideration, it is preferable to ensure that the optical properties of the film are uniform in the TD direction after tenter stretching and before slitting by taking measures such as allowing enough time for the film temperature to become uniform in the width direction during preheating, varying the shape and size of the tenter's hot and cooling air outlets in the width direction, varying the air speed in the width direction, and providing auxiliary heating means at the edges. It is also preferable to reduce temperature fluctuations in the tenter to minimize fluctuations in the MD direction. In the present invention, it is possible to slit only a portion of the produced long film whose optical properties fall within the above range, for example, only the central portion, and use it. However, from an economical point of view, it is preferable to slit and remove a narrow portion. Furthermore, it is preferable to produce a wide film and slit it to obtain multiple films. For this purpose, it is preferable to adjust the stretching conditions during tenter stretching in film production so that the optical properties are uniform across the width of the film. Since retardation from an oblique direction tends to increase due to unevenness in film thickness and fluctuations in orientation, it is preferable to control both with high precision.

[0149] (Easy adhesion layer) The high Re polarizer protective film may be provided with an easy-adhesion layer (easy-adhesion layer P1) in order to improve adhesion to the polarizer and to the alignment layer. The resin used in the adhesion layer is a polyester resin, a polyurethane resin, a polycarbonate resin, an acrylic resin, or the like, and a polyester resin, a polyester polyurethane resin, a polycarbonate polyurethane resin, or an acrylic resin is preferred. The adhesion layer is preferably crosslinked. Examples of crosslinking agents include an isocyanate compound, a melamine compound, an epoxy resin, and an oxazoline compound. Adding a water-soluble resin such as polyvinyl alcohol is also a useful means for improving adhesion to the polarizer.

[0150] The adhesive layer can be formed by applying a water-based coating containing these resins and, if necessary, adding a crosslinking agent, particles, etc., to the high Re polarizer protective film and drying the coating. Examples of particles include those used in the substrate described above. The adhesive layer may be provided offline on the stretched film, but is preferably provided in-line during the film-forming process. When provided in-line, it may be provided either before longitudinal stretching or transverse stretching, but is preferably coated just before transverse stretching, and then dried and crosslinked in a preheating, heating, and heat treatment process using a tenter. When in-line coating is performed just before longitudinal stretching using rolls, it is preferable to dry the coated film in a vertical dryer and then introduce it into the stretching rolls. The coating amount of the easy-adhesion layer (coating amount after drying) is 0.01 to 1 g / m 2 is preferable, and more preferably 0.03 to 0.5 g / m 2 is preferred. In coating the adhesion layer, if the amount of particle aggregates in the coating solution increases, the haze may decrease or the surface roughness may increase. It is preferable to install a filter in the line that sends the coating solution to the coating die or in the coating solution circulation line to remove particle aggregates. The filter used is preferably one with a 95% separation particle size of 10 μm or less, more preferably 5 μm or less, and particularly preferably 2 μm or less. Examples of preferred filters include cartridge filters and bag filters.

[0151] When a film has an easy-adhesion layer, interference occurs between light reflected from the interface between the easy-adhesion layer and the original film roll and light reflected from the interface on the opposite side of the easy-adhesion layer from the original film roll (for example, the interface with a functional layer, adhesive layer, or pressure-sensitive adhesive layer), which can cause interference colors in areas where the thickness of the easy-adhesion layer is uneven. This interference color is noticeable in black display areas and when the power is turned off. To suppress this interference color, it is preferable to reduce the interference.

[0152] In order to reduce interference, it is preferable to make the refractive index of the easy-adhesion layer close to the refractive index of the original film. In the present invention, the original film may have birefringence, and when the refractive index of the original film in the fast axis direction is nf and the refractive index of the original film in the slow axis direction is nl, the refractive index n of the easy-adhesion layer is preferably nf-0.05≦n≦nl+0.05, more preferably nf-0.02≦n≦nl+0.02, and even more preferably nf≦n≦nl.

[0153] For example, when the raw film is made of polyethylene terephthalate, the refractive index in the fast axis direction is 1.6 and the refractive index in the slow axis direction is about 1.7, so the lower limit of the refractive index of the easy-adhesion layer is preferably 1.55, more preferably 1.57, more preferably 1.58, even more preferably 1.59, and particularly preferably 1.6. The upper limit of the refractive index of the easy-adhesion layer is preferably 1.75, more preferably 1.73, more preferably 1.72, even more preferably 1.71, and particularly preferably 1.7.

[0154] The refractive index of the adhesive layer may be birefringent when the adhesive layer is stretched after coating by in-line coating. In this case, the refractive index of the adhesive layer is the average refractive index in the fast axis direction and the slow axis direction. The refractive index of the adhesive layer can be measured, for example, by applying a coating liquid of the adhesive layer to a glass plate or the like, drying it, and using an ellipsometer or the like.

[0155] In order to achieve the refractive index within the above range, a method of adjusting the refractive index of the resin used in the easy-adhesion layer, a method of adding particles with a high refractive index, or the like is preferred. Since the refractive index of a resin can be increased by the addition of an aromatic component, it is preferable to use a resin having a benzene ring or a naphthalene ring in the main chain or side chain, particularly a resin having a naphthalene ring. Specifically, polyesters copolymerized with naphthalene dicarboxylic acid are preferred. Polyesters copolymerized with naphthalene dicarboxylic acid may be blended with other resins as needed. They may also be used as polyester polyols for polyester polyurethanes. The naphthalene dicarboxylic acid component in the polyester is preferably 30 to 90 mol %, more preferably 40 to 80 mol %, assuming that the total acid components are 100 mol %.

[0156] The lower limit of the refractive index of the high refractive index particles is preferably 1.7, more preferably 1.75, and the upper limit of the refractive index of the high refractive index particles is preferably 3, more preferably 2.7, and even more preferably 2.5. As the high refractive index particles, particles containing a high refractive index metal oxide are preferred. Examples of such metal oxides include TiO (refractive index 2.7), ZnO (refractive index 2.0), SbO (refractive index 1.9), SnO (refractive index 2.1), ZrO (refractive index 2.4), NbO (refractive index 2.3), CeO (refractive index 2.2), TaO (refractive index 2.1), YO (refractive index 1.8), LaO (refractive index 1.9), InO (refractive index 2.0), CrO (refractive index 2.5), and composite oxides containing these metal atoms. Among these, SnO particles, TiO particles, ZrO particles, and TiO-ZrO composite particles are preferred.

[0157] The high refractive index particles preferably have an average particle size of 5 nm or more, more preferably 10 nm or more, even more preferably 15 nm or more, and particularly preferably 20 nm or more. When the high refractive index particles have an average particle size of 5 nm or more, they are less likely to aggregate, which is preferable.

[0158] The average particle size of the high refractive index particles is preferably 200 nm or less, more preferably 150 nm or less, even more preferably 100 nm or less, and particularly preferably 60 nm or less. When the average particle size of the high refractive index particles is 200 nm or less, transparency is good, which is preferable.

[0159] The content of high refractive index particles in the adhesive layer is preferably 2% by mass or more, more preferably 3% by mass or more, even more preferably 4% by mass or more, and particularly preferably 5% by mass or more. When the content of high refractive index particles in the adhesive layer is 2% by mass or more, the refractive index of the adhesive layer can be kept high and low interference can be effectively obtained, which is preferable.

[0160] The content of high refractive index particles in the adhesive layer is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and particularly preferably 20% by mass or less. When the content of high refractive index particles in the adhesive layer is 50% by mass or less, film-forming properties are maintained, which is preferable.

[0161] It is preferable that an easy-adhesion layer containing high-refractive-index particles is laminated on at least one surface of the polarizer protective film, and furthermore, it is preferable that the viewing-side polarizer protective film of the viewing-side polarizing plate has an easy-adhesion layer containing high-refractive-index particles, and in particular, it is preferable that the viewing-side surface of the polarizer protective film has an easy-adhesion layer containing high-refractive-index particles.

[0162] (Functional layer) When a high Re polarizer protective film is used as a viewer-side polarizing plate, it is also preferable to provide a functional layer such as a hard coat layer, an antireflection layer, a low-reflection layer, an antiglare layer, or an antistatic layer on the side of the high Re polarizer protective film opposite to the surface on which the polarizer is laminated. In particular, the high Re polarizer protective film is often the outermost surface on the viewer side of a liquid crystal display device, and it is preferable to provide one of an antireflection layer, a low-reflection layer, and an antiglare layer. Antireflection layers, low-reflection layers, and antiglare layers are collectively referred to as reflection-reducing layers. Reflection-reducing layers not only prevent external light from being reflected on the liquid crystal display screen, making it difficult to see, but also suppress interfacial reflection, reducing or making iridescence less noticeable. In addition, in a high Re polarizer protective film provided with a functional layer, the film in its state before the functional layer is provided is referred to as the substrate film. The substrate film may also include the above-mentioned easy-adhesion layer.

[0163] The upper limit of the reflectance of the high Re polarizer protective film measured from the reflection-reducing layer side is preferably 5%, more preferably 4%, even more preferably 3%, particularly preferably 2%, and most preferably 1.5%. A reflectance below the upper limit reduces reflection of external light and improves screen visibility. The lower limit of the reflectance is not particularly limited, but from a practical standpoint, it is preferably 0.01%, and more preferably 0.1%. There are various types of reflection-reducing layers, such as low-reflection layers, anti-reflection layers, and anti-glare layers.

[0164] (Low reflective layer) The low-reflection layer is typically a low refractive index layer, and when provided on the surface of the substrate film, it has the function of reducing the difference in refractive index between the film and air, thereby reducing reflectance.

[0165] (Anti-reflection layer) The antireflection layer is a layer that controls reflection by controlling the thickness of the low refractive index layer and causing interference of reflected light at the interface. The thickness of the low refractive index layer is preferably about the wavelength of visible light (400 to 700 nm) / (refractive index of the low refractive index layer×4). It is also a preferred embodiment to provide a high refractive index layer between the antireflection layer and the substrate film, and two or more low refractive index layers and / or high refractive index layers may be provided to further enhance the antireflection effect through multiple interference. The high refractive index layer and the low refractive index layer together are sometimes referred to as the antireflection layer.

[0166] In the case of an anti-reflection layer, the upper limit of the reflectance is preferably 2%, more preferably 1.5%, even more preferably 1.2%, and particularly preferably 1%.

[0167] (low refractive index layer) The refractive index of the low refractive index layer is preferably 1.45 or less, more preferably 1.42 or less, and is preferably 1.2 or more, more preferably 1.25 or more. The refractive index of the low refractive index layer is a value measured at a wavelength of 589 nm.

[0168] The thickness of the low refractive index layer is not limited, but may be set appropriately within the range of about 30 nm to 1 μm. When used as an antireflection layer, the thickness of the low refractive index layer is preferably 70 to 120 nm, more preferably 75 to 110 nm.

[0169] Preferred examples of the low refractive index layer include (1) a layer made of a resin composition containing a binder resin and low refractive index particles, (2) a layer made of a fluororesin that is a low refractive index resin, (3) a layer made of a fluororesin composition containing silica or magnesium fluoride, and (4) a thin film of a low refractive index material such as silica or magnesium fluoride.

[0170] The binder resin contained in the resin composition (1) can be any resin, including polyester, polyurethane, polyamide, polycarbonate, acrylic, etc. Among them, acrylic is preferred, and it is preferable that the binder resin is obtained by polymerizing (crosslinking) a photopolymerizable compound by light irradiation.

[0171] Examples of the photopolymerizable compound include a photopolymerizable monomer, a photopolymerizable oligomer, and a photopolymerizable polymer, which can be appropriately adjusted and used. As the photopolymerizable compound, a combination of a photopolymerizable monomer and a photopolymerizable oligomer or a photopolymerizable polymer is preferred. These photopolymerizable monomers, photopolymerizable oligomers, and photopolymerizable polymers are preferably polyfunctional.

[0172] Examples of polyfunctional monomers include pentaerythritol triacrylate (PETA), dipentaerythritol hexaacrylate (DPHA), pentaerythritol tetraacrylate (PETTA), dipentaerythritol pentaacrylate (DPPA), etc. Monofunctional monomers may be used in combination to adjust coating viscosity and hardness.

[0173] Examples of polyfunctional oligomers include polyester (meth)acrylate, urethane (meth)acrylate, polyester-urethane (meth)acrylate, polyether (meth)acrylate, polyol (meth)acrylate, melamine (meth)acrylate, isocyanurate (meth)acrylate, and epoxy (meth)acrylate.

[0174] Examples of the polyfunctional polymer include urethane (meth)acrylate, isocyanurate (meth)acrylate, polyester-urethane (meth)acrylate, and epoxy (meth)acrylate.

[0175] In addition to the above components, the coating agent may contain a polymerization initiator, a catalyst for a crosslinking agent, a polymerization inhibitor, an antioxidant, an ultraviolet absorber, a leveling agent, a surfactant, and the like.

[0176] Examples of the low refractive index particles contained in the resin composition (1) include silica particles (for example, hollow silica particles) and magnesium fluoride particles, and among these, hollow silica particles are preferred. Such hollow silica particles can be produced by the production method described in the examples of JP-A No. 2005-099778, for example.

[0177] The average particle size of the primary particles of the low refractive index particles is preferably from 5 to 200 nm, more preferably from 5 to 100 nm, and even more preferably from 10 to 80 nm. The low refractive index particles are more preferably surface-treated with a silane coupling agent, and particularly preferably surface-treated with a silane coupling agent having a (meth)acryloyl group. .

[0178] The content of the low refractive index particles in the low refractive index layer is preferably 10 to 250 parts by mass, more preferably 50 to 200 parts by mass, and even more preferably 100 to 180 parts by mass, relative to 100 parts by mass of the binder resin.

[0179] As the fluorine-based resin (2), a polymerizable compound containing at least a fluorine atom in the molecule or a polymer thereof can be used. The polymerizable compound is not particularly limited, but is preferably one having a curing reactive group such as a photopolymerizable functional group or a thermosetting polar group. Alternatively, a compound having a plurality of these curing reactive groups at the same time may be used. In contrast to this polymerizable compound, the polymer does not have the above-mentioned curing reactive group.

[0180] As the compound having a photopolymerizable functional group, for example, a wide variety of fluorine-containing monomers having an ethylenically unsaturated bond can be used.

[0181] It is also preferred to add a known polysiloxane-based or fluorine-based antifouling agent to the low refractive index layer as appropriate for the purpose of improving fingerprint resistance.

[0182] The surface of the low refractive index layer may be an uneven surface to provide anti-glare properties, but it is also preferable that the surface is a smooth surface. When the surface of the low refractive index layer is smooth, the arithmetic mean roughness SRa (JIS B0601:1994) of the surface of the low refractive index layer is preferably 20 nm or less, more preferably 15 nm or less, even more preferably 10 nm or less, and particularly preferably 1 to 8 nm. The ten-point mean roughness Rz (JIS B0601:1994) of the surface of the low refractive index layer is preferably 160 nm or less, more preferably 50 to 155 nm.

[0183] (high refractive index layer) The refractive index of the high refractive index layer is preferably 1.55 to 1.85, and more preferably 1.56 to 1.7. The refractive index of the high refractive index layer is a value measured at a wavelength of 589 nm.

[0184] The thickness of the high refractive index layer is preferably 30 to 200 nm, more preferably 50 to 180 nm. The high refractive index layer may be a multi-layer structure, but preferably two or less layers, more preferably a single layer. In the case of a multi-layer structure, the total thickness of the multi-layer structure is preferably within the above range.

[0185] When there are two high refractive index layers, it is preferable that the refractive index of the high refractive index layer on the low refractive index layer side is higher. Specifically, it is preferable that the refractive index of the high refractive index layer on the low refractive index layer side is 1.6 to 1.85, and the refractive index of the other high refractive index layer is 1.55 to 1.7.

[0186] The high refractive index layer is preferably made of a resin composition containing high refractive index particles and a resin. Among these, preferred high refractive index particles include antimony pentoxide particles, zinc oxide particles, titanium oxide particles, cerium oxide particles, tin-doped indium oxide particles, antimony-doped tin oxide particles, yttrium oxide particles, and zirconium oxide particles, with titanium oxide particles and zirconium oxide particles being particularly preferred.

[0187] Two or more types of high refractive index particles may be used in combination. In particular, it is preferable to add first high refractive index particles and second high refractive index particles having a smaller surface charge amount in order to prevent aggregation.

[0188] The resins used in the high refractive index layer are the same as those listed for the low refractive index layer, except for the fluorine-based resin.

[0189] In order to flatten the low refractive index layer provided on the high refractive index layer, it is preferable that the surface of the high refractive index layer is also flat. The method for flattening the surface of the high refractive index layer can be the same as the method for flattening the low refractive index layer described above.

[0190] The average particle size of the low refractive index particles and the primary particles of the low refractive index particles is preferably from 5 to 200 nm, more preferably from 5 to 100 nm, and even more preferably from 10 to 80 nm. These particles are more preferably surface-treated, more preferably surface-treated with a silane coupling agent, and particularly preferably surface-treated with a silane coupling agent having a (meth)acryloyl group.

[0191] The content of the low refractive index particles in the low refractive index layer is preferably 10 to 250 parts by mass, more preferably 50 to 200 parts by mass, and even more preferably 100 to 180 parts by mass, relative to 100 parts by mass of the binder resin.

[0192] The content of the low refractive index particles and high refractive index particles in each layer is preferably 10 to 400 parts by mass, more preferably 30 to 250 parts by mass, even more preferably 50 to 200 parts by mass, and particularly preferably 80 to 180 parts by mass, relative to 100 parts by mass of the resin.

[0193] The high refractive index layer and the low refractive index layer can be formed, for example, by applying a resin composition containing a photopolymerizable compound to a substrate film, drying it, and then irradiating the coated resin composition with light such as ultraviolet light to polymerize (crosslink) the photopolymerizable compound.

[0194] The resin compositions of the high refractive index layer and the low refractive index layer may contain, as necessary, thermoplastic resins, thermosetting resins, solvents, polymerization initiators, dispersants, surfactants, antistatic agents, silane coupling agents, thickeners, coloring inhibitors, colorants (pigments, dyes), defoamers, leveling agents, flame retardants, ultraviolet absorbers, adhesion promoters, polymerization inhibitors, antioxidants, surface modifiers, lubricants, and the like.

[0195] (Anti-glare layer) The anti-glare layer is a layer that has an uneven surface to cause diffused reflection, thereby preventing the shape of the light source from being reflected when external light is reflected on the surface and reducing glare.

[0196] The arithmetic mean roughness (SRa) of the unevenness on the surface of the antiglare layer is preferably 0.02 to 0.25 μm, more preferably 0.02 to 0.15 μm, and even more preferably 0.02 to 0.12 μm.

[0197] The ten-point average roughness (Rzjis) of the unevenness on the surface of the antiglare layer is preferably 0.15 to 2 μm, more preferably 0.20 to 1.2 μm, and even more preferably 0.3 to 0.8 μm.

[0198] SRa and Rzjis are calculated from a roughness curve measured using a contact type roughness meter in accordance with JIS B0601-1994 or JIS B0601-2001.

[0199] Examples of methods for providing an antiglare layer on a substrate film include the following methods. Coating of anti-glare layer paint containing particles (fillers) The resin for the anti-glare layer is cured while in contact with a mold with a concave-convex structure. The resin for the anti-glare layer is applied to a mold with a concave-convex structure and then transferred onto the base film. - Applying paints that undergo spinodal decomposition during drying and film formation

[0200] The lower limit of the thickness of the antiglare layer is preferably 0.1 μm, more preferably 0.5 μm, and the upper limit of the thickness of the antiglare layer is preferably 100 μm, more preferably 50 μm, and even more preferably 20 μm.

[0201] The refractive index of the antiglare layer is preferably 1.20 to 1.80, and more preferably 1.40 to 1.70. The refractive index of the antiglare layer is a value measured at a wavelength of 589 nm. The low refractive index layer may be provided with irregularities to form an antiglare low reflection layer, or the surface of the hard coat layer or high refractive index layer may be made irregular, and a low refractive index layer may be provided thereon to provide an antireflection function to form an antiglare antireflection layer.

[0202] (Hard coat layer) It is also a preferred embodiment to provide a hard coat layer as an underlying layer of the reflection-reducing layer. The hard coat layer preferably has a pencil hardness of H or more, more preferably 2H or more. The hard coat layer can be provided, for example, by applying and curing a composition solution of a thermosetting resin or a radiation curable resin.

[0203] Examples of thermosetting resins include acrylic resins, urethane resins, phenolic resins, urea melamine resins, epoxy resins, unsaturated polyester resins, silicone resins, and combinations thereof. In the thermosetting resin composition, a curing agent is added to the curable resin as needed.

[0204] The radiation-curable resin is preferably a compound having a radiation-curable functional group, and examples of the radiation-curable functional group include ethylenically unsaturated bond groups such as (meth)acryloyl, vinyl, and allyl groups, as well as epoxy and oxetanyl groups. Among these, the ionizing radiation-curable compound is preferably a compound having an ethylenically unsaturated bond group, more preferably a compound having two or more ethylenically unsaturated bond groups, and even more preferably a polyfunctional (meth)acrylate compound having two or more ethylenically unsaturated bond groups. The polyfunctional (meth)acrylate compound may be a monomer, oligomer, or polymer.

[0205] Specific examples of these include those listed above as binder resins. To achieve the hardness required for a hard coat, the compound having a radiation-curable functional group preferably contains 50% by mass or more, more preferably 70% by mass or more, of difunctional or higher functional monomers, and more preferably 50% by mass or more, more preferably 70% by mass or more, of trifunctional or higher functional monomers. The compounds having a radiation-curable functional group can be used alone or in combination of two or more.

[0206] The thickness of the hard coat layer is preferably in the range of 0.1 to 100 μm, more preferably in the range of 0.8 to 20 μm.

[0207] The refractive index of the hard coat layer is more preferably 1.45 to 1.7, and even more preferably 1.5 to 1.6. The refractive index of the hard coat layer is a value measured at a wavelength of 589 nm.

[0208] The refractive index of the hard coat layer can be adjusted by adjusting the refractive index of the resin, or by adjusting the refractive index of the particles when particles are added. Examples of the particles include those exemplified as particles for the antiglare layer. In the present invention, the hard coat layer may also be referred to as the reflection-reducing layer.

[0209] When a functional layer is provided, an easy-adhesion layer (easy-adhesion layer P2) may be provided between the substrate and the functional layer. The easy-adhesion layer P2 is preferably made of the resins and crosslinking agents listed above for the easy-adhesion layer P1. The easy-adhesion layer P1 and the easy-adhesion layer P2 may have the same composition or different compositions. The adhesive layer P2 is also preferably provided in-line. The adhesive layer P1 and the adhesive layer P2 may be coated and dried in that order, but it is also preferred to coat them on both sides simultaneously.

[0210] When the high Re polarizer protective film is used in a light source-side polarizing plate, the above-mentioned functional layer is not necessarily required, but a functional layer may be laminated thereon. In particular, to prevent scratches due to contact with a diffuser plate, prism plate, lens plate, reflective polarizing plate, etc. of the light source unit, it is preferable to provide a hard coat layer on the surface opposite to the surface on which the polarizer is laminated. It is also preferable to provide a reflection-reducing layer or an anti-reflection layer, since this allows light from the light source to be transmitted more efficiently and reduces reflectance, thereby further suppressing color spots. The reflection-reducing layer or the anti-reflection layer is preferably provided on the surface opposite to the surface on which the polarizer is laminated. When a high Re polarizer protective film is used for the light source-side polarizing plate and the above-mentioned functional layer is provided on the surface of the high Re polarizer protective film opposite to the surface on which the polarizer is laminated, the outermost surface of the functional layer preferably satisfies the above-mentioned surface roughnesses SRa and SRz. Having the above-mentioned surface roughness prevents scratches on the film of the light source unit and the surface of the functional layer while maintaining good sliding properties with the various film surfaces of the light source unit of the liquid crystal display device, and prevents deterioration of image quality over long-term use.

[0211] When a functional layer other than an antiglare layer is provided in the high Re polarizer protective film, the upper limits of SRa and SRz of the outermost surface of the functional layer are preferably the same as those of the polarizer protective film described above, and the lower limits of SRa and SRz of the outermost surface of the functional layer are preferably the same as those of the polarizer protective film described above.

[0212] (polarizer) As the polarizer, for example, a polarizer in which iodine or an organic dichroic dye is adsorbed onto uniaxially stretched polyvinyl alcohol (PVA), a polarizer in which a liquid crystal compound and an organic dichroic dye are oriented, a liquid crystal polarizer made of a liquid crystal dichroic dye, a wire grid type polarizer, etc. can be used without any particular limitation.

[0213] A film-like polarizer made of uniaxially stretched polyvinyl alcohol (PVA) with iodine or an organic dichroic dye adsorbed thereon and a rolled-up polarizer protective film can be bonded together using a PVA-based or UV-curable adhesive or pressure-sensitive adhesive, and then wound into a roll. The thickness of this type of polarizer is preferably 5 to 30 μm, more preferably 8 to 25 μm, and particularly preferably 10 to 20 μm. The thickness of the adhesive or pressure-sensitive adhesive is preferably 1 to 10 μm, more preferably 2 to 5 μm.

[0214] Also preferred is a polarizer in which PVA is coated on an unstretched substrate such as PET or polypropylene, and the PVA is then uniaxially stretched together with the substrate to adsorb iodine or an organic dichroic dye. When using this polarizer, the polarizer surface (the surface not covered with the substrate) of the polarizer laminated on the substrate is bonded to a polarizer protective film with an adhesive or pressure-sensitive adhesive, and the substrate used in producing the polarizer is then peeled off, thereby bonding the polarizer protective film to the polarizer. In this case, too, the polarizer is preferably bonded in a roll and wound up. The thickness of this type of polarizer is preferably 1 to 10 μm, more preferably 2 to 8 μm, and particularly preferably 3 to 6 μm. The thickness of the adhesive or pressure-sensitive adhesive is preferably 1 to 10 μm, more preferably 2 to 5 μm.

[0215] In the case of a liquid crystal polarizer, a polarizing plate can be produced by laminating an oriented polarizer made of a liquid crystal compound and an organic dichroic dye on a polarizer protective film, or by applying a coating liquid containing a liquid crystal dichroic dye to a polarizer protective film, drying the coating liquid, and curing the liquid crystal polarizer with light or heat. Methods for orienting a liquid crystal polarizer include rubbing the surface of the object to be coated, and irradiating the surface with polarized ultraviolet light to align and cure the liquid crystal polarizer. The surface of the polarizer protective film may be directly rubbed and then coated with the coating liquid, or the coating liquid may be directly applied to the polarizer protective film and then irradiated with polarized ultraviolet light. Another preferred method is to provide an orientation layer on the polarizer protective film before providing the liquid crystal polarizer (i.e., laminating the liquid crystal polarizer on the polarizer protective film via the orientation layer). Methods for providing an orientation layer include: A method of coating polyvinyl alcohol and its derivatives, polyimide and its derivatives, acrylic resin, polysiloxane derivatives, etc., and then rubbing the surface to form an alignment layer (rubbing alignment layer), A method in which a coating liquid containing a polymer or monomer with photoreactive groups such as cinnamoyl groups and chalcone groups and a solvent is applied, and then the coating liquid is irradiated with polarized ultraviolet light to harden the alignment layer (photoalignment layer). etc.

[0216] The polarizer film and the polarizer can also be bonded together by providing a liquid crystal polarizer on a film having releasability in accordance with the above-described method, bonding the liquid crystal polarizer surface to the polarizer film with an adhesive or pressure-sensitive adhesive, and then peeling off the film having releasability.

[0217] The thickness of the liquid crystal polarizer is preferably 0.1 to 7 μm, more preferably 0.3 to 5 μm, and particularly preferably 0.5 to 3 μm. The thickness of the adhesive or pressure-sensitive adhesive is preferably 1 to 10 μm, and more preferably 2 to 5 μm.

[0218] (Lamination of polarizer and polarizer protective film) The high Re polarizer protective film is preferably laminated on the surface of the polarizer opposite the cell. When a polarizer and a high Re polarizer protective film are laminated to form a polarizing plate, the angle between the absorption axis of the polarizer and the slow axis of the high Re polarizer protective film is preferably 90°±7° or less. Here, "or less" refers only to the number after "±" and means 83 to 97°, and the same applies below. The angle means an acute angle of 83° to 90°. The angle between the absorption axis of the polarizer and the slow axis of the high Re polarizer protective film is more preferably 90°±5° or less, even more preferably 90°±3° or less, particularly preferably 90°±2° or less, and most preferably 90°±1.5° or less. The above angle is preferably maintained throughout the entire polarizing plate. The angle between the absorption axis of the polarizer and the slow axis of the high Re polarizer protective film is also preferably 0°±7° or less. Here, "or less" applies only to the number immediately after ±, and means -7 to 7 degrees, and the same applies below. The angle means an acute angle of 0 to 7 degrees. The angle between the absorption axis of the polarizer and the slow axis of the high Re polarizer protective film is more preferably 0 degrees ±5 degrees or less, even more preferably 0 degrees ±3 degrees or less, particularly preferably 0 degrees ±2 degrees or less, and most preferably 0 degrees ±1.5 degrees or less. It is preferable that the above angle is true over the entire range of the polarizing plate.

[0219] In terms of industrial production, it is preferable that the angle between the absorption axis of the polarizer and the slow axis of the high Re polarizer protective film is approximately perpendicular (90 degrees ± 7 degrees or less). Furthermore, when the angle between the absorption axis of the polarizer and the slow axis of the high Re polarizer protective film is approximately perpendicular, the vibration direction of the polarized light passing through the polarizer is the direction of the slow axis (high refractive index) of the polarizer protective film, and the application of the present invention is also effective in terms of the tendency for reflection at the interface of the polarizer protective film to occur.

[0220] As described above, when a birefringent resin film is used as a polarizer protective film and a KSF light source is used, color spots tend to appear when observed from a specific direction. However, the present invention encompasses a technique for adjusting the retardation of the film to a range in which color spots are less noticeable when observed from this specific direction. By keeping the deviation of the angle between the absorption axis of the polarizer and the slow axis of the polarizer protective film within a certain range, the direction in which color spots tend to appear and the retardation range in which color spots are less noticeable in the film can be accurately matched, and it is thought that the occurrence of color spots can be more effectively controlled.

[0221] Furthermore, by setting the angle between the absorption axis of the polarizer and the slow axis of the polarizer protective film within the above range, it is possible to prevent the occurrence of color spots when the film is observed obliquely from the normal direction toward the absorption axis direction of the polarizer or a direction perpendicular to the absorption axis. When the angle between the absorption axis of the polarizer and the slow axis of the polarizer protective film is exactly 0 degrees or 90 degrees, even when the film is observed obliquely toward the absorption axis direction of the polarizer or a direction perpendicular to the absorption axis, the vibration direction of the polarized light is 0 degrees or 90 degrees with respect to the slow axis of the high Re film, and linearly polarized light is not disturbed. However, when the angle between the absorption axis of the polarizer and the slow axis of the polarizer protective film deviates beyond the above range, the linearly polarized light is disturbed and becomes elliptically polarized light, and color spots may be observed.

[0222] When the polarizer protective film is a high Re film exceeding 8000 nm and a conventional yellow phosphor is used as the light source, color spots are observed due to the influence of external light such as fluorescent lamps if the angle between the absorption axis of the polarizer and the slow axis of the polarizer protective film is significantly different from 0 degrees or 90 degrees.

[0223] On the other hand, as described above, the color spots that are controlled in the present invention by adjusting the angle between the absorption axis of the polarizer and the slow axis of the polarizer protective film are color spots that occur due to the KSF light source itself. It is believed that the color mottling controlled in the present invention requires more advanced adjustment for the following reasons. Color spots caused by a high-intensity backlight source are more noticeable than color spots caused by indoor lighting. LCD displays using KSF light sources have excellent color reproducibility, making color spots more noticeable. LCD displays using KSF light sources are preferably used in large LCD displays, and such large LCD displays with high image quality are often used for screenings in home theaters, museums, etc. In such cases, color spots caused by the backlight light source tend to become more noticeable when the room light is darkened. Indoor lighting is also increasingly being replaced by white LED lighting that uses yellow phosphors, making the rainbow spots caused by KSF light sources more noticeable. In the manufacture of polarizing plates, a polarizer is typically laminated onto a long polarizer protective film to produce a long polarizing plate, which is then cut to the required width and length for use in an image display device. Therefore, in order to ensure that the optical properties and variations in these properties of the polarizer protective film used in the polarizing plate of an image display device fall within the above-described ranges, it is preferable to use a polarizer protective film of a long polarizing plate whose optical properties in the TD direction of the polarizer protective film fall within the desired ranges and variations as described above. To achieve this, when manufacturing a long polarizing plate, it is preferable to first use a polarizer protective film whose optical properties in the TD direction of the film fall within the desired ranges as described above. Furthermore, it is preferable to use a long polarizer protective film whose thickness unevenness in the MD direction falls within the above-described range throughout its entire length. Since it is difficult to measure the thickness at 100 mm intervals throughout the entire MD direction, the thickness variation in the MD direction determined based on data measured at wider intervals, such as by reusing online thickness measurement data, may be used. The width of the long polarizing plate and the long polarizer protective film is preferably 400 to 3000 mm, more preferably 500 to 2500 mm, and even more preferably 600 to 2200 mm. The length of the long polarizing plate and the long polarizer protective film is preferably 100 to 10000 m, more preferably 300 to 7000 m, and even more preferably 500 to 5000 m.

[0224] (Liquid crystal cell side of polarizer) The surface of the polarizer facing the liquid crystal cell may be directly attached to the liquid crystal cell with an adhesive or pressure-sensitive adhesive, or a cured layer may be provided on the polarizer, or a polarizer protective film different from the high Re polarizer protective film described above may be provided. A preferred curable layer is the above-mentioned hard coat layer.

[0225] Examples of the polarizer protective film on the liquid crystal cell side include a cellulose-based (TAC) film, an acrylic film, a polycyclic olefin (COP) film, etc. The polarizer protective film on the liquid crystal cell side may have almost zero retardation, or may be a phase difference film known as an optical compensation film for controlling changes in color tone when the display screen is viewed from an oblique direction.

[0226] To obtain the required retardation in an optical compensation film, methods include stretching the film, coating a retardation layer of a liquid crystal compound or the like on the film, or separately providing a retardation layer of a liquid crystal compound or the like on a release film and transferring the layer. The liquid crystal compound for forming the retardation layer is preferably a rod-shaped liquid crystal compound, a discotic liquid crystal compound, or the like, depending on the required retardation characteristics. The liquid crystal compound preferably has a photocurable reactive group such as a double bond to fix the alignment state. To orient the liquid crystal compound and provide a retardation, an alignment layer is provided as a lower layer of the retardation layer, and the alignment layer is subjected to a rubbing treatment or irradiated with polarized ultraviolet light, thereby imparting alignment controllability such that the liquid crystal compound coated thereon is oriented in a specific direction.

[0227] The retardation of the optical compensation film can be appropriately set depending on the type of liquid crystal cell used, the viewing angle to be secured, and so on.

[0228] The retardation layer can be provided by applying a retardation layer composition coating material. The retardation layer composition coating material may contain a solvent, a polymerization initiator, a sensitizer, a polymerization inhibitor, a leveling agent, a polymerizable non-liquid crystal compound, a crosslinking agent, etc. These can be the same as those described in the alignment control layer and the liquid crystal polarizer section.

[0229] The retardation layer is provided by applying the retardation layer composition coating material onto the release surface of the release film or onto the orientation control layer, followed by drying, heating and curing.

[0230] Among these conditions, the conditions explained in the section on the alignment control layer and the liquid crystal polarizer are preferably used.

[0231] When a polarizer is bonded to a polarizer protective film or a retardation film, an adhesive or pressure-sensitive adhesive is used. A water-based adhesive such as a polyvinyl alcohol adhesive or a photocurable adhesive is preferably used as the adhesive. Examples of photocurable adhesives include acrylic and epoxy adhesives. An acrylic pressure-sensitive adhesive is preferably used as the pressure-sensitive adhesive. The above-mentioned optical compensation film, retardation film, and retardation layer are collectively called an optical compensation layer.

[0232] When the polarizing plate is a circular polarizing plate used for antireflection in an electroluminescence display device or the like, a λ / 4 retardation layer is provided on the image display cell surface of the polarizer. The λ / 4 retardation layer can be provided in the same manner as the optical compensation layer. The λ / 4 retardation layer may be a composite λ / 4 retardation layer that combines a λ / 4 retardation layer and a λ / 2 retardation layer.

[0233] Except for cases where an antiglare layer is provided, the haze of the polarizing plate is preferably 5% or less, more preferably 3% or less, even more preferably 2% or less, and particularly preferably 1.5% or less. The lower limit of the haze is preferably 0.01% or more, and more preferably 0.1% or more.

[0234] (liquid crystal cell) A liquid crystal cell is a cell in which a liquid crystal compound is sealed between thin substrates such as glass substrates on which circuits are formed. When the substrates are glass, the thickness is preferably 1 mm or less, and from the viewpoint of thinning, the thickness is more preferably 0.7 mm or less, even more preferably 0.5 mm or less, and particularly preferably 0.4 mm or less.

[0235] The liquid crystal cell type is not particularly limited, but the VA type and the IPS type are preferred types for applying the present invention because they cause little color shift when viewed from an oblique direction and the absorption axis of the polarizer in these types is parallel or perpendicular to the long side direction of the liquid crystal cell.

[0236] The color filter incorporated into the liquid crystal cell preferably has a maximum and minimum transmittance of 80% or more, more preferably 85% or more, for the blue pixel in the wavelength range of 420 nm to 460 nm. The difference between the maximum and minimum transmittance in the wavelength range of 420 nm to 460 nm is preferably 4% or less, more preferably 3% or less.

[0237] (LCD panel) It is preferable that a polarizing plate is attached to each of the viewing side and the light source side of the liquid crystal cell to form a liquid crystal display panel. The attachment is preferably performed using an adhesive. An acrylic adhesive is preferably used as the adhesive.

[0238] In a liquid crystal panel, the polarizing plate using the high Re polarizer protective film may be either the polarizing plate on the light source side or the polarizing plate on the viewing side, or may be both polarizing plates.

[0239] In particular, when a film having an in-plane retardation of 3,000 to 30,000 nm is used as the light source-side polarizer protective film of the light source-side polarizing plate, color spots are likely to occur when combined with a KSF light source because light passing through the polarizer protective film is affected by the polarizer, and light incident on the high Re polarizer protective film is linearly polarized because it passes through a reflective polarizing plate, etc. Therefore, it is preferable to use a polarizing plate using the high Re polarizer protective film described above as the light source-side polarizing plate.

[0240] When a polarizer using the high Re polarizer protective film described above is used only for the light source-side polarizer, the viewer-side polarizer may be a polarizer using a polarizer protective film with other properties on the side opposite the cell. Examples of polarizer protective films with other properties include birefringent resin films with an in-plane retardation of 1,500 to 30,000 nm, and zero-retardation films such as TAC films, acrylic films, and COP films. The birefringent resin film is preferably a resin exemplified as a high Re polarizer protective film. Alternatively, a resin film using a birefringent resin such as PET with an in-plane retardation of preferably 200 nm or less, more preferably 150 nm or less, may be used. Even when a polarizer protective film with other properties is used, it is preferable that the polarizer protective film be provided with the above-described functional layer. In particular, when a birefringent resin film with an in-plane retardation of 1,500 to 30,000 nm is used, color spots resulting from the polarizer protective film of the viewer-side polarizer can be reduced by providing an antireflection layer or a low-reflection layer. In this case, the polarizer of the viewer-side polarizing plate, the surface of the polarizer on the liquid crystal cell side, adhesive or pressure-sensitive adhesive, etc. are the same as those described for the polarizing plate using a high Re polarizer protective film.

[0241] When a birefringent resin film having an in-plane retardation of 1,500 to 30,000 nm is used, the angle between the slow axis of the birefringent resin film and the absorption axis of the polarizer is preferably approximately 0 degrees (0 degrees ±7 degrees) or approximately 90 degrees (90 degrees ±7 degrees). When the angle is approximately 90 degrees, the in-plane retardation is preferably 3,000 nm or more, more preferably 4,500 nm or more, even more preferably 6,000 nm or more, and particularly preferably 7,000 nm or more. The upper limit of the in-plane retardation is preferably 12,000 nm. Such a film can be produced, for example, by stretching a polyester such as PET 3 to 6 times in the TD direction using a tenter or the like. When the retardation is set to approximately 0 degree, the in-plane retardation is preferably 9000 nm or less, more preferably 8000 nm or less, further preferably 7000 nm or less, and particularly preferably 6000 nm or less. Such a film can be produced, for example, by stretching a polyester such as PET 3 to 6 times in the MD direction between rolls operating at different peripheral speeds. The birefringent resin film preferably has a Re / Rth of 0.6 to 1.2, more preferably 0.7 to 1.0.

[0242] When a polarizing plate using the above-mentioned high Re polarizer protective film is used only for the viewer-side polarizing plate, the polarizer protective film on the side opposite to the cell of the light source-side polarizing plate is preferably a zero-retardation film such as a TAC film, an acrylic film, a COP film, etc. The zero-retardation film preferably has an in-plane retardation of 50 nm or less.

[0243] Generally, in order to enable images to be viewed through polarized sunglasses, the transmission axis of the viewer-side polarizing plate is vertical, and as a result, the transmission axis of the light source-side polarizing plate is horizontal. In a polarizing plate using a stretched PVA polarizer and a polyester high Re polarizer protective film, the transmission axis of the polarizer is approximately parallel to the slow axis of the polarizer protective film, so the slow axis of the viewer-side polarizing plate is vertical and the slow axis of the light source-side polarizing plate is horizontal. Furthermore, since image display devices are rectangular and are often installed with the long side horizontal, when viewed along the long side the image is viewed from a more oblique angle, and it is preferable to further reduce color spots from this direction. For this reason, in a rectangular LCD display device installed with its long sides horizontal, it is preferable that the FI(45), FI(30), and FI(60) of the high Re polarizer protective film of the light source-side polarizing plate be set to the higher ranges within the above-mentioned preferred ranges.

[0244] When polarizers using the above-mentioned high Re polarizer protective film are used for both the light source side polarizer and the viewer side polarizer, the properties of the high Re polarizer protective film of each polarizer may be the same or different as long as they are within the specified ranges. If they are different, it is preferable that the FI(45), FI(30), and FI(60) of the high Re polarizer protective film of the light source side polarizer be higher than those of the viewer side polarizer. Furthermore, the polarizer of the viewer-side polarizing plate, the surface of the polarizer on the liquid crystal cell side, the adhesive or pressure-sensitive adhesive, and the like may be the same or different.

[0245] The liquid crystal display device of the present invention may have a touch panel function built in. Methods for imparting a touch panel function to a liquid crystal display device include a method of providing a separate touch sensor on the viewing side of the liquid crystal cell, an in-cell type or on-cell type method of providing an electrode as a touch sensor on the substrate of the liquid crystal cell, and a method of providing an electrode as a touch sensor on a surface cover sheet. [Example]

[0246] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples, and appropriate modifications can be made within the scope of the present invention, and all such modifications are included in the technical scope of the present invention. The methods for evaluating physical properties, etc. in the following examples are as follows.

[0247] (1) Light source spectrum The LCD panel was removed from the LCD display device, and the center of the light source unit, including the diffuser and brightness enhancement film, was measured at a polar angle of 0 degrees, approximately 5 mm away from the light source unit, using a Hamamatsu Photonics multichannel spectrophotometer PMA-12 (C10027-01). An ND-8 filter was used to adjust the amount of light. The measurement interval was approximately 0.75 nm.

[0248] (2A) Retardation from oblique direction The measurement device used was an OPTIPRO-STD manufactured by Shintech Co., Ltd. Several samples measuring 40 mm in the fast axis direction and 60 mm in the slow axis direction were cut out consecutively from the center of the film in the fast axis direction, and placed on the sample stage so that the slow axis direction was approximately parallel to the X direction of the measurement stage. The measurement was performed under the following conditions. Axis definition Slow axis: 0° ··Axis search:ON Output data: Retardation ·Wavelength: Monochromatic light 589nm Sample stage ·Incident angle: START-0deg / END-50deg / STEP-5deg Slow axis (azimuth angle direction to measure): START-30deg / END-60deg / STEP-5deg From the calculated measurements, the values ​​at a polar angle of 50 degrees and azimuth angles of 30 degrees, 45 degrees, and 60 degrees were used as the measurement values ​​for each sample, and the averages of the measurements for the three samples were used as the Rob(30), Rob(45), and Rob(60) for that film. Because the measurement values ​​for each sample may contain errors due to ripple noise, we checked whether the data varied smoothly with respect to the polar and azimuth angles around the polar and azimuth angles used. If the change was not smooth, we either reattached the same sample and measured again, or changed the sample and measured again, and used the average of the three samples that were measured correctly. When changing the sample, we also cut out a sample adjacent to the fast axis for remeasurement. (2B) Retardation from an oblique direction The measurement device used was an OPTIPRO-STD manufactured by Shintech Co., Ltd. The sample was 40 mm in the fast axis direction and 60 mm in the slow axis direction, and was placed on the sample stage so that the slow axis direction was approximately parallel to the X direction of the measurement stage. The measurement was performed under the following conditions. Axis definition Slow axis: 0° ··Axis search:ON Output data: Retardation ·Wavelength: Monochromatic light 589nm Sample stage ·Incident angle:START-0deg / END-50deg / STEP-5deg Slow axis (azimuth angle direction to measure): START-30deg / END-60deg / STEP-5deg Of the calculated measurements, the values ​​at a polar angle of 50 degrees and azimuth angles of 30 degrees, 45 degrees, and 60 degrees were taken as the measurement values ​​for each sample, and the averages of the measurements for the three samples were taken as the Rob(30), Rob(45), and Rob(60) for that film. Note that, because there is a possibility that erroneous values ​​may occur in the measurement values ​​for each sample due to ripple noise, we checked whether the data changed smoothly with respect to the polar angle and azimuth angle around the polar angle and azimuth angle used. If the change was not smooth, the same sample was reattached and measured again, and the average of the three correctly measured values ​​was taken.

[0249] For long polarizer protective films, the first sample was cut from the center in the width direction of a long film slit to the width to be attached to the polarizer, and the second and third samples were cut from both ends. Subsequently, samples were cut from the position where the first sample was cut toward both ends of the film width. At this time, the centers of the 40 x 60 mm samples were spaced 100 mm apart, and the edges were cut out to a position where samples of the specified size could be cut out. Furthermore, if the remaining edge width after cutting out both edges was 60 mm or more, a sample was cut out from the center of the edge width.

[0250] In the case of a polarizing plate cut into sheets for incorporation into a display device, when the long side or short side coincides with the width direction of the long polarizer protective film, the value in the width direction of the long film sampled and measured as described above was used as the value of each of the long side or short side. Furthermore, the values ​​of the long side or short side of the polarizing plate sheet that coincides with the length direction of the long polarizer protective film were measured by cutting 11 samples at 100 mm intervals from the center of the long polarizer protective film in the length direction, and these values ​​were used instead. In the examples, since the variation in the TD direction was greater in all films than in the MD direction, the variation in the TD direction was used. When cutting a sample from a polarizing plate incorporated in a display device, for example, the polarizing plate can be immersed in warm water at about 50°C, the polarizer protective film can be gently peeled off from the edge, and a sample can be cut from the obtained polarizer protective film. In this case, the sample is cut from the center of the sheet of film toward both ends in the long and short side directions using the method described above.

[0251] (3) Film Thickness and Variation Measurements were made using an electric micrometer (Militron 1245D, manufactured by Fineruf). The thickness of the film was measured at 50 mm intervals from the center of the width direction toward both ends in the TD direction, and the thickness variation in the TD direction was calculated as (maximum value - minimum value) / average value x 100 (%). In addition, the thickness was measured at 100 points in the center of the width direction of the film at similar intervals in the MD direction, and the thickness variation in the MD direction was calculated in the same way. The larger of the thickness variation in the TD direction or the thickness variation in the MD direction was considered to be the thickness variation of the film. The film thickness was calculated as the average thickness in the TD direction.

[0252] (4) Absorption axis of polarizer A polarizing filter with a known absorption axis and a polarizer were placed on top of a surface light source, and the polarizing filter was rotated until it was at its darkest, at a 90-degree angle to the absorption axis of the polarizer. In the case of a long polarizer made by stretching PVA in the longitudinal direction, the absorption axis direction is the longitudinal direction, so the longitudinal direction can be considered to be the absorption axis direction.

[0253] (5) Slow axis direction of film Measurement was performed using a molecular orientation meter (MOA-6004 molecular orientation meter manufactured by Oji Measurement Instruments Co., Ltd.).

[0254] (6) Three-dimensional surface roughness Using a stylus-type three-dimensional roughness meter (SE-3AK, manufactured by Kosaka Laboratory Co., Ltd.), measurements were taken over a 1 mm measurement length with a 0.25 mm cutoff point and a 0.1 mm / s needle feed rate, with a needle radius of 2 μm and a load of 30 mg. The film was divided into 500 points at 2 μm intervals, and the height of each point was recorded in a three-dimensional roughness analyzer (SPA-11). A similar procedure was repeated 150 times across the width of the film, at 2 μm intervals, across a 0.3 mm width of the film, and the data was recorded in the analyzer. The center surface average roughness (SRa) and ten-point average surface roughness (SRz) were then calculated using the analyzer. Measurements were performed three times, and the average values ​​were used.

[0255] (7) Hayes The haze of the film was measured using a turbidity meter (NHD2000, manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS-K7105.

[0256] (8) Light transmittance at a wavelength of 380 nm Using a spectrophotometer (U-3500 model, manufactured by Hitachi, Ltd.), the light transmittance in the wavelength range of 300 to 500 nm was measured using an air layer as a standard, and the light transmittance at a wavelength of 380 nm was determined.

[0257] (9) Intrinsic viscosity 0.2 g of a sample was dissolved in 50 ml of a mixed solvent of phenol / 1,1,2,2-tetrachloroethane (60 / 40 (weight ratio)), and the viscosity was measured at 30°C using an Ostwald viscometer.

[0258] (10A) Oblique color spot evaluation The backlight unit and liquid crystal panel were removed from a commercially available television (Toshiba REGZA43J10X), and the polarizing plate was peeled off from the liquid crystal panel. The polarizing plate fabricated on the surface of the liquid crystal panel from which the polarizing plate had been peeled off was placed on the opposite side of the liquid crystal cell with the polarizer protective films A to K sandwiching the polarizer, and with the absorption axis of the polarizer facing the same direction as the original polarizing plate. A backlight unit was then attached to prepare a display for evaluation. The space between the liquid crystal cell and the polarizing plate was filled with ion-exchanged water to reduce reflection. The evaluation display was placed horizontally on a desk with the entire screen displayed in white, and the entire screen was viewed from a distance of approximately 2m at azimuth angles of approximately 45 degrees and 135 degrees (halfway between the long and short sides of the screen) and a polar angle (angle from the normal direction) of 50 degrees, and the state of color spots was observed. Five people ranked the screen on the following three levels, and the average was rounded off to determine the evaluation score. The angle is the angle from the center of the screen. The evaluation was carried out in a dark room with the backlight's luminous intensity set to maximum. 1 point: There were areas where unacceptable color variegation was observed. 3 points: Color spots were observed but were acceptable. 5 points: The color spots were not noticeable. As described below, the evaluation was carried out with only the polarizing plate on the viewer side replaced, with only the polarizing plate on the light source side replaced, and with both polarizing plates replaced. (10B) Oblique color spot evaluation The backlight unit and LCD panel were removed from a commercially available television (Toshiba REGZA43J10X), and the polarizer was removed from the LCD panel. The polarizer was then placed on the LCD panel from which the polarizer had been removed, with the high-Resolution polarizer protective film sandwiching the polarizer on the opposite side of the LCD cell, and with the polarizer's absorption axis aligned with the original polarizer. A backlight unit was then attached to create a display for evaluation. The space between the LCD cell and the polarizer was filled with ion-exchanged water to reduce reflections. The evaluation display was placed horizontally on a desk with the entire screen displayed in white, and from a distance of approximately 2 m, at a polar angle (angle from the normal direction) of 50 degrees, participants walked around the desk on which the evaluation display was placed, looking at the entire screen and observing the uniformity of color tones and striped color spots. Five people ranked the display on one of the three levels below, and the average was rounded off to determine the evaluation score. The angle was measured from the center of the screen. The evaluation was carried out in a dark room with the backlight's luminous intensity set to maximum. 1 point: Striped color spots and uneven color tones were observed around the periphery of the screen, especially at the far edge. 3 points: There were some uneven areas of color tone at the far edges of the screen, but this was acceptable. 5 points: The unevenness of the color tone was not noticeable. The emission spectrum of the light source is shown in FIG. 1, and as mentioned above, the distance between peak groups (Wd) was 20.6 nm and the center wavelength (Wc) was 622.1 nm.

[0259] (11) Horizontal and vertical color spot evaluation As with the diagonal color spot evaluation, an evaluation display was prepared and displayed entirely in white. The entire screen was viewed from an angle from the front in the direction of the long side of the screen, and the state of color spotting was observed. The evaluation was carried out by five people, who agreed to rank the display on one of the three levels below. The angle was measured from the center of the screen. The evaluation was carried out in a dark room with the backlight's luminous intensity set to maximum. Rank 1: Iridescence was observed at approximately 60 degrees from the front. Rank 3: Color spots were observed at around 70 degrees from the front. Rank 5: No rainbow spots were observed until viewed from the side.

[0260] (12) Inspection of foreign matter in film A test polarizer is placed on the side of the fabricated polarizer facing the high Re polarizer protective film, so that it is in a crossed Nicol position with the fabricated polarizer. The test polarizer is made of TAC film with no phase difference on both sides and is free of scratches and foreign matter. In this state, an inspection is performed using a Nikon V-12 universal projector (50x projection lens, 50x transmitted illumination light beam switch knob, transmitted light inspection). If foreign matter is present in the high Re polarizer protective film, light will transmit through that area and appear to shine. The number of areas with a major axis of 100 μm or more, areas with a major axis of 50 μm or more but less than 100 μm, and areas with a major axis of 20 μm or more but less than 50 μm are counted, and the total number of each type across the entire polarizer is calculated. If the major axis could not be determined, the defect portion due to the foreign matter detected by the above method was cut out from the polarizing plate and observed under a polarizing microscope at a higher magnification to determine the major axis, with the high Re polarizer protective film side of the polarizing plate facing up and the polarization direction parallel to the polarization direction of the polarizer on the light source side of the polarizing microscope.

[0261] (13) Micro-image uniformity The front was a white image, and every corner of the image was visually inspected from the front at a distance of approximately 20 cm to check for any abnormalities such as foreign matter, dark spots, areas with different color tones, or irregular pixel arrangement. The evaluation was carried out by five people, and the following three-level ranking was determined by consensus. Rank 1: There are many abnormalities and the quality is poor. Rank 3: There were a few areas that felt abnormal, but the quality was not bad. Rank 5: Nothing felt abnormal.

[0262] (14) Amount of antimony atoms in the residue After removing the adhesive layer from the film surface with a razor, the film was cut into small pieces with scissors. 0.1 g of these small pieces was dissolved in 20 mL of a 60 / 40 (weight ratio) mixed solvent of parachlorophenol and tetrachloroethane. The solution was then filtered by water-flow suction filtration using a hydrophilic PTFE membrane filter (Advantec H010A047A) with an average pore size of 0.1 μm. After filtration, the filter was recovered, and the residue on the filter was dissolved in nitric acid to a constant volume. This was used as the test solution. Each sample was prepared in triplicate. Sb in the test solution was measured using a high-resolution inductively coupled plasma mass spectrometer (HR-ICP-MS, Thermo Fisher Scientific).

[0263] (15) Image clarity and brightness Images of landscapes, people, and plants were displayed and observed from the surface, and the clarity (contrast) and brightness were evaluated in comparison with the original image display device. The evaluation was carried out by five people, who unanimously ranked the products into the following three levels: Rank 1: Clarity and brightness were reduced. Rank 3: Slightly less clear and bright, but not noticeable. Rank 5: No noticeable difference in clarity or brightness.

[0264] (16) Interference color evaluation (Formation of hard coat layer) A coating solution for forming a hard coat layer having the following composition was applied to one side of the prepared substrate film using a #10 wire bar, and the coating solution was dried at 70°C for 1 minute to remove the solvent. Next, a high-pressure mercury lamp was used to irradiate the film with the hard coat layer at 300 mJ / cm. 2 The film was irradiated with ultraviolet light of 1000 kJ / cm to obtain a surface protection film having a hard coat layer with a thickness of 5 μm. Coating solution for forming hard coat layer Methyl ethyl ketone 65.00% by mass Dipentaerythritol hexaacrylate 27.20% by mass (Shin Nakamura Chemical A-DPH) Polyethylene diacrylate 6.80% by mass (Shin Nakamura Chemical A-400) Photopolymerization initiator 1.00% by mass (Irgacure 184 manufactured by Ciba Specialty Chemicals) The surface protection film with the hard coating formed was cut into a piece measuring 10 cm (film width direction) x 15 cm (film length direction) to prepare a sample film. A black glossy tape (Nitto Denko Corporation, vinyl tape No. 21; black) was attached to the side of the obtained sample film opposite the hard coating layer. The sample film was placed with the hard coating layer facing up, and observed using a three-wavelength daylight lamp (National Palook, FL 15EX-N 15W) from above at an angle of 40 to 60 cm from the light source, at an angle of 15 to 45°, at a position where the strongest reflection was observed.

[0265] The results of visual observation were ranked according to the following criteria. The observation was carried out by three people familiar with the evaluation, and if there were differences in the evaluation, they were discussed together. ○ and △ were considered to be acceptable. ○: Almost no interference color is observed from any angle △: Slight iridescent coloring is observed ×: Clear iridescent color is observed

[0266] Polyester A (PET(A)): Polyethylene terephthalate with an intrinsic viscosity of 0.62 dl / g PET (A) was produced by the following method. An esterification reactor was charged with 86.4 parts by mass of terephthalic acid and 64.6 parts by mass of ethylene glycol, stirred, and heated. When the temperature reached 200°C, 0.017 parts by mass of antimony trioxide as a catalyst in an ethylene glycol solution, 0.064 parts by mass of magnesium acetate tetrahydrate, and 0.16 parts by mass of triethylamine were charged while stirring. The temperature was then increased under pressure and a pressurized esterification reaction was carried out at a gauge pressure of 0.34 MPa and 240°C. The esterification reactor was then returned to atmospheric pressure and 0.014 parts by mass of phosphoric acid was added. The temperature was then increased to 260°C over 15 minutes, and 0.012 parts by mass of trimethyl phosphate was added. After 15 minutes, the mixture was dispersed using a high-pressure disperser. After 15 minutes, the resulting esterification reaction product was transferred to a polycondensation reactor and subjected to a polycondensation reaction while the temperature was increased under reduced pressure. The polycondensation temperature reached 280°C, and the reaction was carried out at this temperature for 20 minutes. After the polycondensation reaction was completed, the mixture was filtered using a Naslon filter with a 95% cutoff diameter of 5 μm, extruded from a nozzle in the form of a strand, cooled and solidified using cooling water that had been previously filtered (pore diameter: 1 μm or less), and cut into pellets.

[0267] Polyester B (PET(B)): A melt mixture of 10 parts by mass of ultraviolet absorber (2,2'-(1,4-phenylene)bis(4H-3,1-benzoxazinon-4-one) and 90 parts by mass of PET(A). PET (B) was produced by the following method. 10 parts by mass of the dried UV absorber (2,2'-(1,4-phenylene)bis(4H-3,1-benzoxazinon-4-one) and 90 parts by mass of the above PET (A) were mixed, and the mixture was filtered and pelletized in a kneading extruder in the same manner as above to obtain Polyester B containing the UV absorber.

[0268] Polyester C (PEN): Polyethylene naphthalate with an intrinsic viscosity of 0.58 dl / g

[0269] Polyester D (PET(D)) The same procedure was followed as for PET (A), except that the amount of antimony trioxide was 0.04 parts by mass, the phosphorus compound was phosphoric acid alone, which was added simultaneously with the other catalysts, and the maximum temperature of the polycondensation reaction was 290°C for 35 minutes. Polyester E (PET(E)) The procedure was the same as for PET(A), except that PET(D) was used. These polyesters were filtered through a Naslon filter (nominal filtration accuracy: 95% cutoff of 5 μm particles) provided in the melting line for extruding them into strands.

[0270] (Preparation of Adhesion Modifying Coating Solution 1) A water-dispersible sulfonate metal salt-containing copolymerized polyester resin was prepared by conventional transesterification and polycondensation reactions. The dicarboxylic acid components (based on the total dicarboxylic acid components) were 46 mol% terephthalic acid, 46 mol% isophthalic acid, and 8 mol% sodium 5-sulfonatoisophthalate. The glycol components (based on the total glycol components) were 50 mol% ethylene glycol and 50 mol% neopentyl glycol. Next, 51.4 parts by weight of water, 38 parts by weight of isopropyl alcohol, 5 parts by weight of n-butyl cellosolve, and 0.06 parts by weight of a nonionic surfactant were mixed and heated with stirring. When the temperature reached 77°C, 5 parts by weight of the water-dispersible sulfonate metal salt-containing copolymerized polyester resin was added. Stirring was continued until the resin clumps disappeared, and the resin aqueous dispersion was cooled to room temperature to obtain a uniform water-dispersible copolymerized polyester resin solution with a solids concentration of 5.0% by weight. Furthermore, 3 parts by mass of aggregated silica particles (Sylysia 310, manufactured by Fuji Silysia Ltd.) were dispersed in 50 parts by mass of water, and then 0.54 parts by mass of an aqueous dispersion of Sylysia 310 was added to 99.46 parts by mass of the water-dispersible copolymer polyester resin liquid, and 20 parts by mass of water was added with stirring to obtain an adhesive property-modifying coating liquid 1. The coating liquid was filtered through a cartridge filter with a 95% separation particle size of 10 μm.

[0271] (Preparation of Adhesion Modification Coating Liquid 2) (Polymerization of Copolymerized Polyester Resin) A stainless steel autoclave equipped with a stirrer, thermometer, and partial reflux condenser was charged with 381 parts by weight of dimethyl naphthalate, 58.3 parts by weight of dimethyl terephthalate, 41.5 parts by weight of dimethyl-5-sodium sulfoisophthalate, 46.7 parts by weight of diethylene glycol, 245.8 parts by weight of ethylene glycol, and 0.5 parts by weight of tetra-n-butyl titanate. A transesterification reaction was carried out at a temperature of 160 to 220°C over 4 hours. The temperature was then raised to 255°C, and the reaction system was gradually depressurized. The reaction was continued for 1 hour and 30 minutes under a reduced pressure of 30 Pa to obtain copolymer polyester resin (A-1). The resulting copolymer polyester resin was pale yellow and transparent. The composition measured by 1H-NMR was 2,6-naphthalenedicarboxylic acid / terephthalic acid / 5-sodium sulfoisophthalic acid / ethylene glycol / diethylene glycol = 78 / 15 / 7 / / 90 / 10 (mol%).

[0272] (Preparation of Water Dispersion of Polyester) A reactor equipped with a stirrer, thermometer, and reflux device was charged with 20 parts by mass of polyester resin (A-1) and 15 parts by mass of ethylene glycol t-butyl ether, and the mixture was heated to 110°C and stirred to dissolve the resin. After the resin was completely dissolved, 65 parts by mass of water was gradually added to the polyester solution while stirring. After the addition, the solution was cooled to room temperature while stirring to produce a milky white polyester aqueous dispersion (B-1) with a solids content of 20% by mass.

[0273] (Polymerization of Blocked Polyisocyanate Crosslinking Agent) A four-neck flask equipped with a stirrer, thermometer, reflux condenser, nitrogen inlet, and dropping funnel was conditioned with nitrogen, and 600 parts of HMDI and 30 parts of a trihydric alcohol polycaprolactone-based polyester polyol (Daicel Chemical Industries, Ltd., PLACCEL 303, molecular weight 300) were charged. The temperature inside the reactor was maintained at 90°C for 1 hour with stirring to carry out a urethanization reaction. The temperature inside the reactor was then maintained at 60°C, and the isocyanurate catalyst tetramethylammonium caprylate was added. When the yield reached 48%, phosphoric acid was added to stop the reaction, yielding a polyisocyanate composition (C-1).

[0274] Next, a four-neck flask equipped with a stirrer, thermometer, reflux condenser, nitrogen inlet, and dropping funnel was purged with nitrogen and charged with 100 parts of polyisocyanate composition (C-1), 19 parts of methoxypolyethylene glycol having a molecular weight of 400 (manufactured by NOF Corporation, Uniox M400) (reacts with 10% of all isocyanate groups in the polyisocyanate), and 37 parts of propylene glycol monomethyl ether acetate. The mixture was then maintained at 80°C for 7 hours. The reaction mixture temperature was then maintained at 50°C, and 38 parts of methyl ethyl ketoxime was added dropwise. Measurement of the infrared spectrum of the reaction mixture showed that the isocyanate groups had disappeared, yielding an aqueous blocked polyisocyanate resin (C-2) with a solids concentration of 80% by mass.

[0275] Preparation of adhesive property modifying coating solution 2 The following coating materials were mixed and filtered through a cartridge filter with a 95% separation particle size of 10 μm to prepare Coating Solution 2. Particle A is SnO2 with a refractive index of 2.1, and Particle B is silica particles with an average primary particle size of approximately 500 nm. Water 43.26% by mass Isopropanol 30.00% by mass Polyester water dispersion (B-1) 20.07% by mass Water-based blocked polyisocyanate resin (C-2) 0.74% by mass Particle A 5.58% by mass (Taki Chemical Ceramace S-8, solid content 8% by mass) Particle B 0.30% by mass (Nippon Shokubai Seahoster KEW50, solids concentration 15% by mass) Surfactant 0.05% by mass (Dynol 604 manufactured by Nissin Chemical Industry, solid content 100% by mass)

[0276] Preparation of adhesive property modifying coating solution 3 Adhesion-modifying coating solution 3 was obtained in the same manner as adhesion-modifying coating solution 2, except that the polyester water dispersion was changed to B-2 and particles A were changed to SiO2 with a refractive index of 1.46 (Snowtex ZL manufactured by Nissan Chemical Industries, Ltd., solid content concentration 40% by mass).

[0277] (polarizer) A roll of polyvinyl alcohol film having a thickness of 80 μm, which had been continuously dyed in an iodine aqueous solution, was stretched 5 times in the conveying direction, treated in a boric acid solution, washed with water, and dried to obtain a long polarizer.

[0278] (Polarizer protective film A) As raw materials for the intermediate layer of the base film, 90 parts by weight of particle-free PET (A) resin pellets and 10 parts by weight of PET (B) resin pellets containing a UV absorber were dried under reduced pressure (1 Torr) at 135 ° C for 6 hours and then fed into Extruder 2 (for intermediate layer II). PET (A) was dried by conventional methods and fed into Extruder 1 (for outer layers I and III), respectively, and melted at 285 ° C. These two polymers were each filtered through a stainless steel sintered filter medium (nominal filtration accuracy 10 μm particle 95% cut). The two polymers were laminated in a two-type, three-layer merging block, extruded into a sheet from a die, and then wrapped around a casting drum at a surface temperature of 30 ° C using an electrostatic casting method, cooled, and solidified to produce an unstretched film. The output of each extruder was adjusted so that the thickness ratio of layers I, II, and III was 10:80:10.

[0279] Next, a coating amount of 0.08 g / m2 was applied to both sides of the unstretched PET film after drying. 2 After applying the adhesive property-modifying coating solution 1 so that the thickness became 10 μm, the coating was dried for 20 seconds at 80° C. During application, a cartridge filter with a 95% separation particle size of 10 μm was installed in the line sending the coating solution 1 to the coating die to remove particle aggregates.

[0280] The unstretched film with this coating layer formed was introduced into a tenter stretching machine, and while the edges of the film were held with clips, it was introduced into the tenter at 100°C and stretched 4.1 times in the width direction. Next, while maintaining the stretched width in the width direction, it was treated in a heat setting zone at 190°C for 10 seconds, and further relaxed 3.0% in the width direction to obtain a stretched PET film.

[0281] (Polarizer protective films B to H) A polarizer protective film as shown in Table 1 was obtained in the same manner as in the preparation of Polarizer Protective Film A, except that the thickness of the unstretched film was adjusted.

[0282] (Polarizer protective film I)

[0283] An unstretched PET film obtained in the same manner as the polarizer protective film A except for adjusting the thickness was heated to 110°C and stretched 1.08 times between rolls with different peripheral speeds. After that, the coating amount after drying was 0.08 g / m on both sides. 2 The adhesive property modifying coating liquid was applied so that the film was formed into a film having a coating layer of 100°C, and the film was then dried in the same manner as above. The film having the resulting coating layer formed thereon was introduced into a tenter stretching machine, and while holding the ends of the film with clips, the film was introduced into a tenter at 100°C and stretched 4.2 times in the width direction. Next, while maintaining the width stretched in the width direction, the film was treated in a heat setting zone at a temperature of 190°C for 10 seconds, and further subjected to a relaxation treatment of 2.0% in the width direction to obtain a stretched PET film.

[0284] (Polarizer protective film J) A stretched PET film was obtained in the same manner as in Polarizer Protective Film I, except that the thickness was adjusted and the stretching between rolls was set to 1.13 times.

[0285] (Polarizer protection film K) A stretched PET film was obtained in the same manner as in the preparation of Polarizer Protective Film A, except that the thickness was adjusted, the tenter temperature was set to 105°C, and the stretching ratio was set to 5.3 times.

[0286] (Polarizer protection film L and M) An unstretched film with a coating layer formed thereon was obtained in the same manner as in Polarizer Protective Film A, except for adjusting the thickness. The unstretched film with a coating layer formed thereon was introduced into a tenter stretching machine, and while the edges of the film were held with clips, it was introduced into the tenter at 125°C and stretched 4.0 times in the width direction. Next, while maintaining the stretched width in the width direction, it was treated in a heat setting zone at a temperature of 225°C for 10 seconds, and further subjected to a relaxation treatment of 2.0% in the width direction to obtain a stretched PET film.

[0287] (Polarizer Protection Film N) Particle-free PEN resin pellets used as the base film raw material were dried under reduced pressure (1 Torr) at 135°C for 6 hours, then fed into an extruder and melted at 295°C. This polymer was filtered through a sintered stainless steel filter medium (nominal filtration accuracy: 95% cutoff of 10μm particles), extruded into a sheet from a die, and then wrapped around a casting drum with a surface temperature of 30°C using an electrostatic casting method, where it was cooled and solidified to produce an unstretched film.

[0288] Next, the adhesiveness-modifying coating liquid was applied to both sides of this unstretched PEN film so that the coating amount after drying would be 0.08 g / m 2 , and then dried at 80° C. for 20 seconds.

[0289] The unstretched film with this coating layer formed was introduced into a tenter stretching machine, and while the edges of the film were held with clips, it was introduced into the tenter at 130°C and stretched 4.0 times in the width direction. Next, while maintaining the stretched width in the width direction, it was treated in a heat setting zone at a temperature of 210°C for 10 seconds, and further relaxed 3.0% in the width direction to obtain a stretched PEN film.

[0290] (Polarizer protective film O) Except for adjusting the thickness and setting the tenter temperature to 110°C and the stretching ratio to 5.4, a thickness-stretched PET film was obtained in the same manner as for polarizer protective film A. The refractive indices of film O in the nx, ny, and nz directions were measured using an Abbe refractometer, and the in-plane retardation was calculated by multiplying the difference between the nx and ny refractive indices by the thickness, resulting in a value of 7198 nm.

[0291] (Polarizer protective film P) An unstretched PET film obtained in the same manner as Polarizer Protective Film A, except for adjusting the thickness, was introduced into a simultaneous biaxial stretching machine at 125°C and stretched 6 times in the MD direction and 1.8 times in the TD direction. It was then processed in a heat setting zone at 225°C for 10 seconds, and relaxed 3% in the MD direction and 0.5% in the TD direction to obtain a stretched PET film. The in-plane retardation of Film P was 3880 nm.

[0292] The polarizer protective films obtained above were slit at the center where the alignment direction was almost uniform (deviation from the TD direction or MD direction was 0.5 degrees or less). The properties of each polarizer protective film are shown in Table 1.

[0293] [Table 1]

[0294] (Preparation of polarizing plate) (Preparation of polarizing plate 1) Polarizing plates PA1 to PP1 were produced by laminating the polarizer protective film prepared above to one side of a polarizer and a triacetyl cellulose film (40 μm thick) to the other side using a roll-to-roll method. A UV-curable adhesive was used for lamination. In polarizing plates PA1 to PO1, the angle between the slow axis of the polarizer protective film and the absorption axis of the polarizer was 90 degrees, while in PP1 it was 0 degrees, with a deviation of 0.5 degrees or less in both cases.

[0295] (Preparation of polarizing plate 2) A triacetyl cellulose film (40 μm thick) was roll-to-roll laminated to one side of the polarizer and then cut into sheets, and a polarizer protective film D cut into sheets was laminated to the other side with the lamination angle shifted as shown in Table 2, to obtain polarizing plates PD2 to PD4.

[0296] [Table 2]

[0297] (Evaluation using a polarizing plate on the light source side) Only the polarizing plate on the light source side was replaced with the polarizing plate prepared above, and color unevenness was evaluated. The evaluation of color unevenness in the oblique direction was carried out according to (10A). The results are shown in Table 3.

[0298] [Table 3]

[0299] In the case of polarizer plate PA1, which uses polarizer protective film A, Re was low and clear color spots were observed when viewed from an oblique direction. As the film thickness was increased from polarizer protective film B to H and Re was increased, the slight color spots observed when viewed from an oblique direction with polarizer protective film B initially decreased and then increased, and when polarizer protective film H was used, the color spots became clear. As ΔFI / FI(45) increased with polarizer protective films I, J, L, and M, the color spots observed when viewed from an oblique direction tended to increase. No color spots were observed in the horizontal or vertical directions with these samples. In the case of the polarizer protective film K in which the resin was PEN, color spots were not noticeable as long as the FI(45) and the like were within the appropriate range. Next, using Polarizer Protective Film D, color spots were evaluated for polarizing plates (PD2, PD3, PD4) when the angle between the slow axis and the absorption axis of the polarizer was shifted from 90 degrees. As the shift increased, color spots from oblique directions became more pronounced in some areas. Furthermore, color spots from horizontal and vertical directions also began to appear as the shift increased.

[0300] (Evaluation using a polarizing plate on the viewing side) Only the polarizing plate on the viewing side was replaced with the polarizing plate prepared above, and the evaluation of color unevenness in the oblique direction was carried out according to (10A). The results are shown in Table 4. In order to examine the influence of the optical properties of the polarizer protective film, no reflection-reducing layer or the like was provided.

[0301] [Table 4]

[0302] When used as the viewing-side polarizing plate, the overall color unevenness was smaller than when used as the light-source-side polarizing plate, but the tendency was the same.

[0303] (Evaluation of both the light source side polarizer and the viewer side polarizer) Both the light source-side polarizing plate and the viewer-side polarizing plate were replaced with the polarizing plates prepared above, and color unevenness was evaluated. The results are shown in Table 5. A reflection-reducing layer was provided on the side opposite the polarizer of each polarizer protective film of the viewer-side polarizing plate by coating, drying, and curing Opstar TU-2360 (manufactured by Arakawa Chemical Industries, Ltd.). The reflectance measured from the reflection-reducing layer side of Polarizer Protective Film C, which was used as a representative film, was 1.6%. The SRa of the reflection-reducing layer surface was 2 nm, and the SRz was 75 nm. The reflectance was measured at 5 degrees at a wavelength of 550 nm using a spectrophotometer (Shimadzu Corporation, UV-3150). The reflectance was measured by applying black marker to the surface of the film opposite to the surface on which the antireflection layer (or low reflection layer) was provided, and then applying black vinyl tape (Kyowa Vinyl Tape HF-737, 50 mm wide, manufactured by Kyowa Corporation).

[0304] [Table 5]

[0305] As shown in Table 5, it was found that color spots were suppressed even when the polarizer protective film of the present invention was used as the polarizer protective film for both the light-source-side polarizing plate and the viewer-side polarizing plate. Furthermore, when the polarizer protective film of the present invention was used as the polarizer protective film for the light-source-side polarizing plate, color spots were suppressed even when a polyester film other than the polarizer protective film of the present invention was used as the polarizer protective film for the viewer-side polarizing plate.

[0306] (Polarizer protective film a) As raw materials for the intermediate layer of the base film, 90 parts by weight of particle-free PET (A) resin pellets and 10 parts by weight of PET (B) resin pellets containing a UV absorber were dried under reduced pressure (1 Torr) at 135 ° C for 6 hours and then fed into Extruder 2 (for intermediate layer II). PET (A) was dried by conventional methods and fed into Extruder 1 (for outer layers I and III), respectively, and melted at 285 ° C. These two polymers were each filtered through a stainless steel sintered filter medium (nominal filtration accuracy 10 μm particle 95% cut). The two polymers were laminated in a two-type, three-layer merging block, extruded into a sheet from a die, and then wrapped around a casting drum at a surface temperature of 30 ° C using an electrostatic casting method, cooled, and solidified to produce an unstretched film. The output of each extruder was adjusted so that the thickness ratio of layers I, II, and III was 10:80:10.

[0307] Next, a coating amount of 0.08 g / m2 was applied to both sides of the unstretched PET film after drying. 2 After applying the adhesive property-modifying coating solution 2 so that the thickness became 10 μm, the coating was dried for 20 seconds at 80° C. During application, a cartridge filter with a 95% separation particle size of 10 μm was installed in the line sending the coating solution 2 to the coating die to remove particle aggregates.

[0308] The unstretched film with this coating layer was introduced into a tenter stretching machine, and while the film edges were held with clips, it was introduced into the tenter at 100°C and stretched 4.1 times in the width direction. Next, while maintaining the stretched width, it was processed in a heat-setting zone at 190°C for 10 seconds and then further relaxed by 3.0% in the width direction. The uneven edges held by the clips were removed to obtain a stretched PET film measuring 2000 mm in width and 1000 m in length. The nozzle was adjusted so that the hot air from the tenter would be directed primarily at the film edges during the preheating and first half of the heat-setting processes. The resulting film was then divided in half widthwise to obtain a stretched PET film a measuring 1000 mm in width and 1000 m in length. The die was specially designed to optimize the flow distribution through simulations using the resin used, and thickness variations in the TD direction were controlled by linking the thickness measuring device in the film production line with the lip adjustment bolt of the die. Once a stable state was achieved, the product was sampled.

[0309] (Polarizer protective film b) The production was carried out in the same manner as for film a, except that the amount of hot air hitting the film edge was changed by adjusting the nozzle in the preheating process and the first half of the heat setting process, and the control program for the thickness measuring device and the lip adjustment bolt of the nozzle was improved.

[0310] (Polarizer protection film c) The production was carried out in the same manner as for film a, except that no nozzle adjustment was performed in the preheating process and the first half of the heat setting process, the preheating process time was reduced to two-thirds, and no related control was performed between the thickness gauge and the lip adjustment bolt of the nozzle.

[0311] (Polarizer protective film d) A polarizer protective film d was obtained in the same manner as the polarizer protective film a, except that the film was slit into a width of 1000 mm from the center.

[0312] (Polarizer protection film e) A polarizer protective film e was obtained in the same manner as polarizer protective film c, except that the film was slit into a width of 1000 mm from the center.

[0313] (Polarizer protection films f and g) A polarizer protective film f was obtained in the same manner as for polarizer protective film a, except that the thickness was adjusted, the tenter temperature was set to 105°C, and the stretching ratio was set to 5.3. A polarizer protective film g was obtained in the same manner as for polarizer protective film f, except that the thickness control program was the same as for polarizer protective film b. Table 6 shows the properties of each polarizer protective film.

[0314] [Table 6]

[0315] (Preparation of polarizing plate) (Preparation of polarizing plate 1) The polarizer protective film prepared above was laminated to one side of a polarizer, and a triacetyl cellulose film (40 μm thick) was laminated to the other side using a roll-to-roll method to prepare polarizing plates Pa1 to Pg1. A UV-curable adhesive was used for lamination. In each polarizing plate, the angle between the slow axis of the polarizer protective film and the absorption axis of the polarizer was 90 degrees, and the deviation was 0.5 degrees or less.

[0316] [Table 7]

[0317] (Evaluation of both the light source side polarizer and the viewer side polarizer) Both the light source side polarizing plate and the viewer side polarizing plate were replaced with the polarizing plates prepared above, and the oblique color spot evaluation was carried out according to (10B). The results are shown in Table 8. In order to observe the influence of the optical properties of the polarizer protective film, a reflection-reducing layer or the like was not provided.

[0318] [Table 8]

[0319] (Polarizer protection film h) As raw materials for the intermediate layer of the base film, 90 parts by weight of particle-free PET (A) resin pellets and 10 parts by weight of PET (B) resin pellets containing a UV absorber were dried under reduced pressure (1 Torr) at 135 ° C for 6 hours and then fed into Extruder 2 (for intermediate layer II). PET (A) was dried by conventional methods and fed into Extruder 1 (for outer layers I and III), respectively, and melted at 285 ° C. These two polymers were each filtered through a stainless steel sintered filter medium (nominal filtration accuracy 10 μm particle 95% cut). The two polymers were laminated in a two-type, three-layer merging block, extruded into a sheet from a die, and then wrapped around a casting drum at a surface temperature of 30 ° C using an electrostatic casting method, cooled, and solidified to produce an unstretched film. The output of each extruder was adjusted so that the thickness ratio of layers I, II, and III was 10:80:10. The difference between the inner diameter of the gasket at the joint of the flange of the pipe through which the molten resin passes and the inner diameter of the pipe was 50 μm or less, and at the start of operation, resin was released three times for 5 minutes at a flow rate 1.2 times the set resin extrusion amount, after which film production began and the film was sampled 30 minutes after production started.In addition, the filter element was replaced with one that had been cleaned at the start of operation.

[0320] Next, a coating amount of 0.08 g / m2 was applied to both sides of the unstretched PET film after drying. 2 After applying the adhesive property-modifying coating solution 2 so that the thickness became 10 μm, the coating was dried for 20 seconds at 80° C. During application, a cartridge filter with a 95% separation particle size of 10 μm was installed in the line sending the coating solution 2 to the coating die to remove particle aggregates.

[0321] The unstretched film with this coating layer formed was introduced into a tenter stretching machine, and while the edges of the film were held with clips, it was introduced into the tenter at 100°C and stretched 4.1 times in the width direction. Next, while maintaining the stretched width in the width direction, it was treated in a heat setting zone at 190°C for 10 seconds, and further relaxed 3.0% in the width direction to obtain a stretched PET film.

[0322] (Polarizer protective film i) Polarizer protective films as shown in the table were obtained in the same manner as in the preparation of polarizer protective film h, except that the thickness of the unstretched film was adjusted.

[0323] (Polarizer protection film j) After continuous production for one week under the conditions of polarizer protective film h, the film was sampled.

[0324] (Polarizer protection film) The same procedure was carried out as for polarizer protective film h, except that the difference between the inner diameter of the gasket at the joining portion and the inner diameter of the piping was 200 μm, no resin discharge was performed, and the filter was used as it was after one week of continuous production.

[0325] The polarizer protective films obtained above were slit at the center where the alignment direction was almost uniform (deviation from the TD direction or MD direction was 0.5 degrees or less). The properties of each polarizer protective film are shown in Table 9.

[0326] [Table 9]

[0327] (Preparation of polarizing plate) The polarizer protective film prepared above was laminated to one side of a polarizer, and a triacetyl cellulose film (40 μm thick) was laminated to the other side using a roll-to-roll method to prepare polarizing plates Ph1 to Pk1. A UV-curable adhesive was used for lamination. The angle between the slow axis of the polarizer protective film and the absorption axis of the polarizer was 90 degrees, and the deviation was 0.5 degrees or less.

[0328] [Table 10]

[0329] (Display device evaluation) The polarizing plate on the light source side and the polarizing plate on the viewer side were replaced with the polarizing plates prepared above, and evaluation was carried out. The evaluation of color unevenness in the oblique direction was carried out according to (10A). The results are shown in Table 11. In order to examine the influence of the optical properties of the polarizer protective film, no reflection-reducing layer or the like was provided.

[0330] [Table 11]

[0331] (Polarizer protection film) As raw materials for the intermediate layer of the base film, 90 parts by weight of particle-free PET (A) resin pellets and 10 parts by weight of PET (B) resin pellets containing a UV absorber were dried under reduced pressure (1 Torr) at 135 ° C for 6 hours and then fed into Extruder 2 (for intermediate layer II). PET (A) was dried by conventional methods and fed into Extruder 1 (for outer layers I and III), respectively, and melted at 285 ° C. These two polymers were each filtered through a stainless steel sintered filter medium (nominal filtration accuracy 10 μm particle 95% cut). The two polymers were laminated in a two-type, three-layer merging block, extruded into a sheet from a die, and then wrapped around a casting drum at a surface temperature of 30 ° C using an electrostatic casting method, cooled, and solidified to produce an unstretched film. The output of each extruder was adjusted so that the thickness ratio of layers I, II, and III was 10:80:10. The difference between the inner diameter of the gasket at the joint of the flange of the pipe through which the molten resin passes and the inner diameter of the pipe was 50 μm or less, and at the start of operation, resin was released three times for 5 minutes at a flow rate 1.2 times the set resin extrusion amount, after which film production began and the film was sampled 30 minutes after production started.In addition, the filter element was replaced with one that had been cleaned at the start of operation.

[0332] Next, a coating amount of 0.08 g / m2 was applied to both sides of the unstretched PET film after drying. 2 After applying the adhesive property-modifying coating solution 2 so that the thickness became 10 μm, the coating was dried for 20 seconds at 80° C. During application, a cartridge filter with a 95% separation particle size of 10 μm was installed in the line sending the coating solution 2 to the coating die to remove particle aggregates.

[0333] The unstretched film with this coating layer formed was introduced into a tenter stretching machine, and while the edges of the film were held with clips, it was introduced into the tenter at 100°C and stretched 4.1 times in the width direction. Next, while maintaining the stretched width in the width direction, it was treated in a heat setting zone at 190°C for 10 seconds, and further relaxed 3.0% in the width direction to obtain a stretched PET film.

[0334] (Polarizer protection film m) Polarizer protective films as shown in Table 12 were obtained in the same manner as in Polarizer Protective Film 1, except that the thickness of the unstretched film was adjusted.

[0335] (Polarizer protection film n)

[0336] The same procedures were followed as for polarizer protective film 1, except that PET(A) was a dry blend of PET(A) / PET(D)=8 / 2 and PET(B) was a dry blend of PET(B) / PET(E)=8 / 2.

[0337] (Polarizer protection film) The same procedures were carried out as for the polarizer protective film 1, except that PET(A) was changed to PET(D) and PET(B) was changed to PET(E).

[0338] The polarizer protective films obtained above were slit at the center where the alignment direction was almost uniform (deviation from the TD direction or MD direction was 0.5 degrees or less). The properties of each polarizer protective film are shown in Table 12.

[0339] [Table 12]

[0340] (Preparation of polarizing plate) A polarizing plate was produced by laminating the polarizer protective film prepared above to one side of a polarizer and a triacetyl cellulose film (40 μm thick) to the other side using a roll-to-roll method. A UV-curable adhesive was used for lamination. For each polarizing plate, the angle between the slow axis of the polarizer protective film and the absorption axis of the polarizer was 90 degrees, and the deviation in both cases was 0.5 degrees or less.

[0341] [Table 13]

[0342] (Display device evaluation) The polarizing plate on the light source side and the polarizing plate on the viewer side were replaced with the polarizing plates prepared above, and evaluation was carried out. The evaluation of color unevenness in the oblique direction was carried out according to (10A). The results are shown in Table 14. In order to observe the influence of the optical properties of the polarizer protective film, a reflection-reducing layer or the like was not provided.

[0343] [Table 14]

[0344] (Polarizer protective film p) As raw materials for the intermediate layer of the base film, 90 parts by weight of particle-free PET (A) resin pellets and 10 parts by weight of PET (B) resin pellets containing a UV absorber were dried under reduced pressure (1 Torr) at 135 ° C for 6 hours and then fed into Extruder 2 (for intermediate layer II). PET (A) was dried by conventional methods and fed into Extruder 1 (for outer layers I and III), respectively, and melted at 285 ° C. These two polymers were each filtered through a stainless steel sintered filter medium (nominal filtration accuracy 10 μm particle 95% cut). The two polymers were laminated in a two-type, three-layer merging block, extruded into a sheet from a die, and then wrapped around a casting drum at a surface temperature of 30 ° C using an electrostatic casting method, cooled, and solidified to produce an unstretched film. The output of each extruder was adjusted so that the thickness ratio of layers I, II, and III was 10:80:10.

[0345] Next, a coating amount of 0.08 g / m2 was applied to both sides of the unstretched PET film after drying. 2 After applying the adhesive property-modifying coating solution so that the coating solution was 10 μm thick, it was dried for 20 seconds at 80° C. During application, a cartridge filter with a 95% separation particle size of 10 μm was installed in the line sending the coating solution to the coating die to remove particle aggregates.

[0346] The unstretched film with this coating layer formed was introduced into a tenter stretching machine, and while the edges of the film were held with clips, it was introduced into the tenter at 100°C and stretched 4.1 times in the width direction. Next, while maintaining the stretched width in the width direction, it was treated in a heat setting zone at 190°C for 10 seconds, and further relaxed 3.0% in the width direction to obtain a stretched PET film.

[0347] (Polarizer protection film q) Polarizer protective films as shown in Table 15 were obtained in the same manner as in the preparation of polarizer protective film p, except that the thickness of the unstretched film was adjusted.

[0348] (Polarizer protection film)

[0349] A polarizer protective film as shown in Table 15 was obtained in the same manner as in the preparation of polarizer protective film p, except that adhesive property-modifying coating liquid 3 was used.

[0350] The polarizer protective films obtained above were slit at the center where the alignment direction was almost uniform (deviation from the TD direction or MD direction was 0.5 degrees or less). The properties of each polarizer protective film are shown in Table 15.

[0351] [Table 15]

[0352] (Preparation of polarizing plate) A polarizing plate was produced by laminating the polarizer protective film prepared above to one side of a polarizer and a triacetyl cellulose film (40 μm thick) to the other side using a roll-to-roll method. A UV-curable adhesive was used for lamination. For each polarizing plate, the angle between the slow axis of the polarizer protective film and the absorption axis of the polarizer was 90 degrees, and the deviation in both directions was 0.5 degrees or less.

[0353] [Table 16]

[0354] (Evaluation using a polarizing plate on the light source side) Both the light source side polarizing plate and the viewer side polarizing plate were replaced with the polarizing plates prepared above, and evaluation was carried out. Note that the evaluation of oblique color mottling was carried out according to (10A). The results are shown in Table 17. In order to examine the influence of the optical properties of the polarizer protective film, no reflection-reducing layer or the like was provided.

[0355] [Table 17] [Industrial Applicability]

[0356] According to the present invention, it is possible to provide an image display device that has a wide reproducible color gamut and does not show noticeable color spots even when the image display device has an emission spectrum with a steep peak in the red region. The present invention makes it possible to provide a liquid crystal display device that does not produce noticeable color spots and has a wide reproducible color gamut, even when a light source having a steep emission spectrum in the red region, such as a KSF phosphor, is used as a backlight light source. The present invention makes it possible to provide a liquid crystal display device that has a wide reproducible color gamut and produces inconspicuous color spots even when a light source having a steep emission spectrum in the red region, such as a KSF phosphor, is used as a backlight source, and that has almost no defects even when viewed up close. The present invention makes it possible to provide a liquid crystal display device that is bright, vivid, and has a wide reproducible color gamut, without noticeable color spots, even when a light source having a steep emission spectrum in the red region, such as a KSF phosphor, is used as a backlight source. According to the present invention, it is possible to provide an image display device that has a steep emission spectrum in the red region, but which does not have noticeable color spots, has a wide reproducible color gamut, and does not have noticeable interference colors.

Claims

1. An image display device having an image display cell and at least one polarizing plate, the at least one polarizing plate is a polarizing plate in which light incident on the polarizing plate has a plurality of peak groups in a range of 600 to 650 nm, and the polarizing plate has a polarizer protective film having a 45-degree light source compatibility index (FI(45)) calculated by the following formula 1 of 0.4 or more and 0.62 or less, The image display device, wherein the polarizer protective film having a 45-degree light source compatibility index (FI(45)) of 0.4 or more and 0.62 or less is a polyester film. FI(45)=Wd / [Wc / (Rob(45) / Wc)] Equation 1 Rob(45): Retardation of the polarizer protective film measured in the in-plane direction of the film at an angle of 45 degrees from the slow axis direction to the fast axis direction and inclined by 50 degrees from the normal direction. Wd: Peak-to-peak distance of the peak group (nm) Wc: central wavelength of the peak group (nm)

2. An image display device having an image display cell and at least one polarizing plate, the at least one polarizing plate is a polarizing plate in which light incident on the polarizing plate has a plurality of peak groups in a range of 600 to 650 nm; the at least one polarizing plate has a polarizer and at least one polarizer protective film; the at least one polarizer protective film has a 45-degree light source compatibility index (FI(45)) calculated by the following formula 1, measured at 100 mm intervals along the long side direction and at 100 mm intervals along the short side direction, both of which are 0.4 or more and 0.62 or less, The value obtained by subtracting the minimum value from the maximum value of the FI(45) measured at 100 mm intervals along the long side direction, and the value obtained by subtracting the minimum value from the maximum value of the FI(45) measured at 100 mm intervals along the short side direction are both 0.026 or less, The image display device, wherein the at least one polarizer protective film is a polyester film. FI(45)=Wd / [Wc / (Rob(45) / Wc)] Equation 1 Rob(45): Retardation of the polarizer protective film measured in the in-plane direction of the film at an angle of 45 degrees from the slow axis direction to the fast axis direction and inclined by 50 degrees from the normal direction. Wd: Peak-to-peak distance of the peak group (nm) Wc: central wavelength of the peak group (nm)

3. An image display device having an image display cell and at least one polarizing plate, the at least one polarizing plate has a polarizer protective film having a retardation (Rob(45)) of 7,500 nm or more and 11,700 nm or less when measured in an in-plane direction of the film at an angle of 45 degrees from the slow axis direction toward the fast axis direction and in a direction tilted by 50 degrees from the normal direction, the polarizer protective film is a polyester film, and has a retardation (Rob(45)) of 7,500 nm or more and 11,700 nm or less when measured in an in-plane direction of the film at an angle of 45 degrees from the slow axis direction toward the fast axis direction and in a direction tilted by 50 degrees from the normal direction; The image display device is characterized in that the light incident on the at least one polarizing plate includes excited emission of a red phosphor activated with tetravalent manganese ions.

4. An image display device having an image display cell and at least one polarizing plate, the at least one polarizing plate has a polarizer and at least one polarizer protective film; the retardation (Rob(45)) of the at least one polarizer protective film measured in an in-plane direction of the film from the slow axis direction toward the fast axis direction at an angle of 45 degrees and inclined by 50 degrees from the normal direction is 7,500 nm or more and 11,700 nm or less, both of which are measured at 100 mm intervals along the long side direction and at 100 mm intervals along the short side direction, The value obtained by subtracting the minimum value from the maximum value of the Rob (45) measured at 100 mm intervals along the long side direction, and the value obtained by subtracting the minimum value from the maximum value of the Rob (45) measured at 100 mm intervals along the short side direction are both 500 nm or less, the at least one polarizer protective film is a polyester film; The image display device is characterized in that the light incident on the at least one polarizing plate includes excited emission of a red phosphor activated with tetravalent manganese ions.

5. A liquid crystal display device having a backlight light source, a light source-side polarizing plate, a liquid crystal cell, and a viewer-side polarizing plate, the emission spectrum of the backlight light source has a plurality of peaks in the range of 600 to 650 nm; At least one of the light-source-side polarizing plate and the viewer-side polarizing plate is a polarizing plate having a polarizer protective film having a 45-degree light source compatibility index (FI(45)) calculated by the following formula 1 of 0.4 or more and 0.62 or less, The liquid crystal display device, wherein the polarizer protective film having a 45-degree light source compatibility index (FI(45)) of 0.4 or more and 0.62 or less is a polyester film. FI(45)=Wd / [Wc / (Rob(45) / Wc)] Equation 1 Rob(45): Retardation of the polarizer protective film measured in the in-plane direction of the film at an angle of 45 degrees from the slow axis direction to the fast axis direction and inclined by 50 degrees from the normal direction. Wd: Peak-to-peak distance of the peak group (nm) Wc: central wavelength of the peak group (nm)

6. A liquid crystal display device having a backlight light source, a light source-side polarizing plate, a liquid crystal cell, and a viewer-side polarizing plate, the emission spectrum of the backlight light source has a plurality of peaks in the range of 600 to 650 nm; At least one of the light-source-side polarizing plate and the viewer-side polarizing plate has a polarizer and at least one polarizer protective film, the at least one polarizer protective film has a 45-degree light source compatibility index (FI(45)) calculated by the following formula 1, measured at 100 mm intervals along the long side direction and at 100 mm intervals along the short side direction, both of which are 0.4 or more and 0.62 or less, The value obtained by subtracting the minimum value from the maximum value of the FI(45) measured at 100 mm intervals along the long side direction, and the value obtained by subtracting the minimum value from the maximum value of the FI(45) measured at 100 mm intervals along the short side direction are both 0.026 or less, The liquid crystal display device, wherein the at least one polarizer protective film is a polyester film. FI(45)=Wd / [Wc / (Rob(45) / Wc)] Equation 1 Rob(45): Retardation of the polarizer protective film measured in the in-plane direction of the film at an angle of 45 degrees from the slow axis direction to the fast axis direction and inclined by 50 degrees from the normal direction. Wd: Peak-to-peak distance of the peak group (nm) Wc: central wavelength of the peak group (nm)

7. A liquid crystal display device having a backlight light source, a light source-side polarizing plate, a liquid crystal cell, and a viewer-side polarizing plate, the backlight source emits red phosphors activated with tetravalent manganese ions by excitation light, at least one of the light-source-side polarizing plate and the viewer-side polarizing plate is a polarizer protective film having a retardation (Rob(45)) of 7,500 nm or more and 11,700 nm or less when measured in an in-plane direction of the film at an angle of 45 degrees from the slow axis direction toward the fast axis direction and in a direction tilted by 50 degrees from the normal direction, the polarizer protective film is a polyester film, and has a retardation (Rob(45)) of 7,500 nm or more and 11,700 nm or less when measured in an in-plane direction of the film at an angle of 45 degrees from the slow axis direction toward the fast axis direction and in a direction tilted by 50 degrees from the normal direction.

8. A liquid crystal display device having a backlight light source, a light source-side polarizing plate, a liquid crystal cell, and a viewer-side polarizing plate, the backlight source emits red phosphors activated with tetravalent manganese ions by excitation light, At least one of the light-source-side polarizing plate and the viewer-side polarizing plate has a polarizer and at least one polarizer protective film, the retardation (Rob(45)) of the at least one polarizer protective film measured in an in-plane direction of the film from the slow axis direction toward the fast axis direction at an angle of 45 degrees and inclined by 50 degrees from the normal direction is 7,500 nm or more and 11,700 nm or less, both of which are measured at 100 mm intervals along the long side direction and at 100 mm intervals along the short side direction, The value obtained by subtracting the minimum value from the maximum value of the Rob (45) measured at 100 mm intervals along the long side direction, and the value obtained by subtracting the minimum value from the maximum value of the Rob (45) measured at 100 mm intervals along the short side direction are both 500 nm or less, The liquid crystal display device, wherein the at least one polarizer protective film is a polyester film.

9. A method for selecting a combination of a backlight light source and a polarizing plate in a liquid crystal display device having a backlight light source, a light source-side polarizing plate, a liquid crystal cell, and a viewer-side polarizing plate, comprising: (a) selecting a backlight source having an emission spectrum with a plurality of peaks in the range of 600 to 650 nm; and (b) selecting at least one of the light-source-side polarizing plate and the viewer-side polarizing plate, the polarizing plate having a polarizer protective film having a 45-degree light source compatibility index (FI(45)) calculated by the following formula 1 of 0.4 or more and 0.62 or less; Including, The polarizer protective film having a 45-degree light source compatibility index (FI(45)) of 0.4 or more and 0.62 or less is a polyester film. FI(45)=Wd / [Wc / (Rob(45) / Wc)] Equation 1 Rob(45): Retardation of the polarizer protective film measured in the in-plane direction of the film at an angle of 45 degrees from the slow axis direction to the fast axis direction and inclined by 50 degrees from the normal direction. Wd: Peak-to-peak distance of the peak group (nm) Wc: central wavelength of the peak group (nm)

10. A method for selecting a combination of a backlight light source and a polarizing plate in a liquid crystal display device having a backlight light source, a light source-side polarizing plate, a liquid crystal cell, and a viewer-side polarizing plate, comprising: (a) selecting a backlight source having an emission spectrum with a plurality of peaks in the range of 600 to 650 nm; and (b) at least one of the light source side polarizing plate and the viewer side polarizing plate, a step of selecting a polarizing plate having a polarizer protective film in which the 45-degree light source compatibility index (FI(45)) calculated by the following formula 1, measured at 100 mm intervals along the long side direction and at 100 mm intervals along the short side direction, is 0.4 or more and 0.62 or less, and both the value obtained by subtracting the minimum value from the maximum value of the FI(45) measured at 100 mm intervals along the long side direction and the value obtained by subtracting the minimum value from the maximum value of the FI(45) measured at 100 mm intervals along the short side direction are 0.026 or less; Including, the polarizer protective film in which both of the value obtained by subtracting the maximum value from the minimum value of the FI(45) measured at 100 mm intervals along the long side direction and the value obtained by subtracting the maximum value from the minimum value of the FI(45) measured at 100 mm intervals along the short side direction are 0.026 or less is a polyester film. FI(45)=Wd / [Wc / (Rob(45) / Wc)] Equation 1 Rob(45): Retardation of the polarizer protective film measured in the in-plane direction of the film at an angle of 45 degrees from the slow axis direction to the fast axis direction and inclined by 50 degrees from the normal direction. Wd: Peak-to-peak distance of the peak group (nm) Wc: central wavelength of the peak group (nm)

Images