JP6907462B2 - Liquid crystal display device - Google Patents

Description

The present invention relates to a liquid crystal display device. More specifically, the present invention relates to a liquid crystal display device in which the occurrence of iridescent color spots is improved.

The polarizing plate used in the liquid crystal display device (LCD) usually has a structure in which a polarizing element obtained by dyeing iodine on polyvinyl alcohol (PVA) or the like is sandwiched between two polarizing element protective films, and is used as a polarizing element protective film. Usually, a triacetyl cellulose (TAC) film is used. In recent years, as LCDs have become thinner, there has been a demand for thinner polarizing plates. However, if the thickness of the TAC film used as the protective film is reduced for this purpose, sufficient mechanical strength cannot be obtained, and there arises a problem that the moisture permeability is deteriorated. Further, the TAC film is very expensive, and a polyester film has been proposed as an inexpensive alternative material (Patent Documents 1 to 3), but there is a problem that iridescent color spots are observed.

When an oriented polyester film having birefringence is arranged on one side of the polarizer, the polarization state of the linearly polarized light emitted from the backlight unit or the polarizer changes when passing through the polyester film. The transmitted light exhibits an interference color peculiar to retardation, which is the product of birefringence and thickness of the oriented polyester film. Therefore, if a discontinuous emission spectrum such as a cold-cathode tube or a hot-cathode tube is used as the light source, the transmitted light intensity differs depending on the wavelength, resulting in iridescent color spots (see: Proceedings of the 15th Microoptical Conference, No. 30-31).

As a means for solving the above problems, a white light source having a continuous and wide emission spectrum such as a white light emitting diode is used as the backlight light source, and an oriented polyester film having a certain retardation is used as the polarizer protective film. It has been proposed (Patent Document 4). White light emitting diodes have a continuous and wide emission spectrum in the visible light region. Therefore, focusing on the envelope shape of the interference color spectrum due to the transmitted light transmitted through the compound refracting body, it is possible to obtain a spectrum similar to the emission spectrum of the light source by controlling the retardation of the oriented polyester film. It made it possible to suppress rainbow spots.

In addition, by making the orientation direction of the oriented polyester film perpendicular to or parallel to the polarization direction of the polarizing plate, the linearly polarized light emitted from the polarizer passes through the oriented polyester film while maintaining the polarized state. become. Further, by controlling the birefringence of the oriented polyester film to enhance the uniaxial orientation, light incident from an oblique direction can also pass while maintaining the polarized state. When the oriented polyester film is viewed from an angle, a deviation occurs in the orientation spindle direction as compared with a case where it is viewed from directly above, but when the uniaxial orientation is high, the deviation in the orientation spindle direction when viewed from an angle becomes small. Therefore, it is considered that the deviation between the direction of linearly polarized light and the direction of the main axis of orientation is small, and the change in the polarization state is less likely to occur. By controlling the emission spectrum of the light source, the orientation state of the birefringent, and the direction of the main axis of orientation in this way, changes in the polarization state are suppressed, rainbow-shaped color spots do not occur, and visibility is significantly improved. It was thought that.

Japanese Unexamined Patent Publication No. 2002-116320 Japanese Unexamined Patent Publication No. 2004-219620 Japanese Unexamined Patent Publication No. 2004-205773 WO2011 / 162198

Due to the increasing demand for expanding the color gamut of liquid crystal display devices in recent years, the peaks of the emission spectrum are in each wavelength region of the blue region (400 nm or more and less than 495 nm), the green region (495 nm or more and less than 600 nm), and the red region (600 nm or more and 780 nm or less). A liquid crystal display device has been developed using a white light emitting diode having a top and a light emitting spectrum having a relatively narrow half-value width of a peak in the red region (600 nm or more and 780 nm or less) as a backlight light source.

When a liquid crystal display device is industrially produced using a polarizing plate using a polyester film as a polarizer protective film, the directions of the transmission axis of the polarizer and the phase advance axis of the polyester film are usually arranged to be perpendicular to each other. Will be done. This is because the polyvinyl alcohol film, which is a polarizer, is produced by longitudinally uniaxially stretching, and the polyester film, which is the protective film thereof, is produced by longitudinally stretching and then laterally stretching. This is because the main axis direction is the lateral direction, and when a polarizing plate is manufactured by laminating these long objects, the phase advance axis of the polyester film and the transmission axis of the polarizer are usually in the vertical direction. In this case, an oriented polyester film having a specific retardation is used as the polyester film, and the backlight source is represented by, for example, a white LED composed of a light emitting element in which a blue light emitting diode and an yttrium aluminum garnet yellow phosphor are combined. By using a light source having a continuous and wide emission spectrum, the iridescent color spots are significantly improved, but the half-value width of the peak in the red region (600 nm or more and 780 nm or less) is relatively narrow (less than 5 nm). We have found that there is still a new problem of rainbow spots when using a backlit light source consisting of a white light emitting diode with a spectrum.

That is, the subject of the present invention is to have a peak top of the emission spectrum in each wavelength region of the blue region (400 nm or more and less than 495 nm), the green region (495 nm or more and less than 600 nm), and the red region (600 nm or more and 780 nm or less), and red. When a polyester film is used as the polarizer protective film in a liquid crystal display device having a white light emitting diode having a light emitting spectrum having a relatively narrow half-value width (less than 5 nm) of a peak in a region (600 nm or more and 780 nm or less) as a backlight source. Also, it is to provide a liquid crystal display device and a polarizing plate in which rainbow spots are suppressed.

A typical invention is as follows.
Item 1.
A liquid crystal display device having a backlight light source, two polarizing plates, and a liquid crystal cell arranged between the two polarizing plates.
The backlight source has a peak top of the emission spectrum in each wavelength region of 400 nm or more and less than 495 nm, 495 nm or more and less than 600 nm, and 600 nm or more and 780 nm or less, and has the highest peak intensity in the wavelength region of 600 nm or more and 780 nm or less. A white light emitting diode having an emission spectrum with a peak width of less than 5 nm.
At least one of the two polarizing plates is obtained by laminating a polyester film on at least one surface of the polarizing element via an adhesive layer.
The difference between the refractive index of the adhesive layer and the refractive index of the polyester film in the direction parallel to the transmission axis of the polarizer is 0.13 or less.
Liquid crystal display device.
Item 2.
The emission spectrum of the backlight source is
The half width of the peak with the highest peak intensity in the wavelength region of 400 nm or more and less than 495 nm is 5 nm or more.
Item 2. The liquid crystal display device according to Item 1, wherein the half width of the peak having the highest peak intensity in the wavelength region of 495 nm or more and less than 600 nm is 5 nm or more.
Item 3.
Item 2. The liquid crystal display device according to Item 1 or 2, wherein the polyester film has a retardation of 1500 to 30000 nm.

The liquid crystal display device of the present invention has a wide color gamut, and can ensure good visibility in which the occurrence of rainbow-shaped color spots is significantly suppressed at any observation angle.

(Liquid crystal display device)
Generally, a liquid crystal display device is composed of a rear surface module, a liquid crystal cell, and a front surface module in the order from the side facing the backlight source to the side displaying an image (visual recognition side). The rear module and the front module are generally composed of a transparent substrate, a transparent conductive film formed on the surface of the liquid crystal cell side thereof, and a polarizing plate arranged on the opposite side thereof. Here, the polarizing plate is arranged on the side facing the backlight light source in the rear module, and is arranged on the image display side (visual recognition side) in the front module. The backlight may be configured by an edge light system having a light guide plate, a reflector, or the like as a constituent member, or a direct type system. In addition to the backlight source, the polarizing plate, and the liquid crystal cell, the liquid crystal display device may appropriately have other configurations such as a color filter, a lens film, a diffusion sheet, and an antireflection film. A brightness improving film may be provided between the light source side polarizing plate and the backlight light source. Examples of the brightness improving film include a reflective polarizing plate that transmits one linearly polarized light and reflects the linearly polarized light orthogonal to the linearly polarized light. As the reflective polarizing plate, for example, a brightness improving film of the DBEF (registered trademark) (Dual Brightness Enhancement Film) series manufactured by Sumitomo 3M Ltd. is preferably used. The reflective polarizing plate is usually arranged so that the absorption axis of the reflective polarizing plate and the absorption axis of the light source side polarizing plate are parallel to each other.

(Backlight light source)
The liquid crystal display device of the present invention comprises at least a backlight source and a liquid crystal cell arranged between two polarizing plates as constituent members. The backlight source has a peak top in each wavelength region of 400 nm or more and less than 495 nm, 495 nm or more and less than 600 nm, and 600 nm or more and 780 nm or less, and has the highest peak intensity in the wavelength region of 600 nm or more and 780 nm or less. A white light emitting diode having an emission spectrum having a half width of less than 5 nm is preferable.

The configuration of the backlight may be an edge light system having a light guide plate, a reflector, or the like as a constituent member, or a direct type system, but in the present invention, the backlight source of the liquid crystal display device is used. The peak top of the emission spectrum is in each wavelength region of 400 nm or more and less than 495 nm, 495 nm or more and less than 600 nm, and 600 nm or more and 780 nm or less, and the half-value width of the peak with the highest peak intensity in the wavelength region of 600 nm or more and 780 nm or less is A backlight source composed of a white light emitting diode having an emission spectrum of less than 5 nm is preferable. The upper limit of the half width of the peak having the highest peak intensity in the wavelength region of 600 nm or more and 780 nm or less is preferably less than 5 nm, more preferably less than 4 nm, and further preferably less than 3.5 nm. The lower limit is preferably 1 nm or more, more preferably 1.5 nm or more. When the half width of the peak is less than 5 nm, the color gamut of the liquid crystal display device is widened, which is preferable. Further, if the half width of the peak is less than 1 nm, the luminous efficiency may deteriorate, which is not preferable. The shape of the emission spectrum is designed from the balance between the required color gamut and luminous efficiency. Here, the full width at half maximum is the peak width (nm) at half the intensity of the peak intensity at the wavelength of the peak top.

The application of a backlight source having an emission spectrum having the above-mentioned characteristics to an LCD is a technique that has attracted attention due to the increasing demand for color gamut expansion in recent years. An LED that uses a conventionally used white LED (for example, a light emitting element that combines a blue light emitting diode and an yttrium aluminum garnet yellow phosphor) as a backlight source has a spectrum that can be recognized by the human eye. Only about 20% of the colors can be reproduced. On the other hand, when a backlight source having an emission spectrum having the above-mentioned characteristics is used, it is said that 60% or more of colors can be reproduced.

The wavelength region of 400 nm or more and less than 495 nm is more preferably 430 nm or more and 470 nm or less. The wavelength region of 495 nm or more and less than 600 nm is more preferably 510 nm or more and 560 nm or less. The wavelength region of 600 nm or more and 780 nm or less is more preferably 600 nm or more and 700 nm or less, and even more preferably 610 nm or more and 680 mn or less.

The peak half width at the peak top of each wavelength region of 400 nm or more and less than 495 nm (half width of the peak having the highest peak intensity in each wavelength region) of the emission spectrum is not particularly limited, but is 400 nm or more and less than 495 nm. The half width of the peak having the highest peak intensity in the wavelength region of 495 nm or more is preferably 5 nm or more, and the half width of the peak having the highest peak intensity in the wavelength region of 495 nm or more and less than 600 nm is preferably 5 nm or more. From the viewpoint of ensuring an appropriate color gamut, the upper limit of the peak half width (half width of the peak having the highest peak intensity in each wavelength region) at the peak top of each wavelength region of 400 nm or more and less than 495 nm and 495 nm or more and less than 600 nm is set. It is preferably 140 nm or less, preferably 120 nm or less, preferably 100 nm or less, more preferably 80 nm or less, still more preferably 60 nm or less, and even more preferably 50 nm or less.

Specific examples of the white light source having the emission spectrum having the above-mentioned characteristics include a phosphor-type white light emitting diode in which a blue light emitting diode and a phosphor are combined. Examples of the red phosphor among the phosphors include a fluoride phosphor (also referred to as “KSF”) having a _{composition formula of K 2} SiF ₆ : Mn ^{4+, and others.} The Mn ⁴⁺ activated fluoride complex phosphor is a phosphor having Mn ⁴⁺ as an activator and a fluoride complex salt of an alkali metal, an amine or an alkaline earth metal as a parent crystal. The fluoride complex forming the parent crystal has a coordination center of a trivalent metal (B, Al, Ga, In, Y, Sc, lanthanoid) and a tetravalent metal (Si, Ge, Sn, Ti, Zr, There are those of Re, Hf) and those of pentavalent metals (V, P, Nb, Ta), and the number of fluorine atoms coordinated around them is 5 to 7.

Preferable examples of Mn ⁴⁺ activated fluoride complex phosphors are A ₂ [MF ₆ ]: Mn (A is one or more selected from Li, Na, K, Rb, Cs, NH ₄ ; M is Ge, Si, One or more selected from Sn, Ti, Zr), E [MF ₆ ]: Mn (E is one or more selected from Mg, Ca, Sr, Ba, Zn; M is selected from Ge, Si, Sn, Ti, Zr. (A is one or more selected from Li, Na, K, Rb, Cs, NH ₄ ), Ba _0.65 , Zr _0.35 F _2.70 : Mn, A ₃ [ZrF _{7]: Mn (A is one or more selected from Li, Na, K, Rb, Cs, NH 4)} , A ₂ [MF ₅ ]: Mn (A is one or more selected from Li, Na, K, Rb, Cs, NH ₄ ; M is one or more selected from Al, Ga, In), A ₃ [MF ₆ ] : Mn (A is one or more selected from Li, Na, K, Rb, Cs, NH ₄ ; M is one or more selected from Al, Ga, In), Zn ₂ [MF ₇ ]: Mn (M is Al, One or more selected from Ga and In), A [In ₂ F ₇ ]: Mn (A is one or more selected from Li, Na, K, Rb, Cs, NH _{4) and the like.}

One of the preferred Mn ⁴⁺ activated fluoride complex phosphors is selected from _{A 2} MF ₆ : Mn (A is Li, Na, K, Rb, Cs, NH ₄₎ having a hexafluoro complex salt of an alkali metal as a parent crystal. One or more; M is one or more selected from Ge, Si, Sn, Ti, and Zr). Of these, A is one or more selected from K (potassium) or Na (sodium), and M is Si (silicon) or Ti (titanium). Among them, it is particularly preferable that A is K (the ratio of K to the total amount of A is 99 mol% or more) and M is Si. The activating element is preferably Mn (manganese) of 100%, but Ti, Zr, Ge, Sn, Al, Ga, B, In, Cr, in the range of less than 10 mol% with respect to the total amount of the activating element. Fe, Co, Ni, Cu, Nb, Mo, Ru, Ag, Zn, Mg and the like may be contained. When M is Si, the ratio of Mn in the total of Si and Mn is preferably in the range of 0.5 mol% to 10 mol%. Other preferred ^{Mn 4+} -activated fluoride complex phosphor, the formula _{A 2 + x M y Mn z} F n (A is Na and K; M is Si and Al; -1 ≦ x ≦ 1 and 0.9 ≦ y + z ≦ 1 .1 and 0.001 ≦ z ≦ 0.4 and 5 ≦ n ≦ 7) can be mentioned.

As the backlight source, a white light emitting diode having a blue light emitting diode and at least a fluoride phosphor as a phosphor is preferable, and a fluoride having at least K ₂ SiF ₆ : Mn ^{4+ as a blue light emitting diode and a phosphor is particularly preferable.} It is a white light emitting diode having a phosphor. For example, a commercially available product such as NSSW306FT, which is a white LED manufactured by Nichia Corporation, can be used.

Among the phosphors, as the green phosphor, for example, a sialon-based phosphor having a basic composition of β-SiAlON: Eu or the like, or a silicate-based fluorescent substance having a basic composition of _{(Ba, Sr) 2} SiO _{4: Eu or the like.} , Others are exemplified.

When a plurality of peaks are present in any of the wavelength region of 400 nm or more and less than 495 nm, the wavelength region of 495 nm or more and less than 600 nm, or the wavelength region of 600 nm or more and 780 nm or less, it is considered as follows.
When the plurality of peaks are independent peaks, it is preferable that the half width of the peak having the highest peak intensity is in the above range. Further, for other peaks having an intensity of 70% or more of the highest peak intensity, it is more preferable that the half width is similarly in the above range. Here, the independent peak has an intensity region that is halved of the peak intensity on both the short wavelength side and the long wavelength side of the peak. That is, when a plurality of peaks overlap and each peak does not have a region of intensity that is 1/2 of the peak intensity, the plurality of peaks are regarded as one peak as a whole. For one peak having such a shape in which a plurality of peaks overlap, the width of the peak (nm) at half the intensity of the highest peak intensity among them is set as the half width.
Of the plurality of peaks, the peak with the highest peak intensity is set as the peak top.
The peak having the highest peak intensity in the wavelength region of 400 nm or more and less than 495 nm, or the wavelength region of 495 nm or more and less than 600 nm, or the wavelength region of 600 nm or more and 780 nm or less has an independent relationship with the peaks in other wavelength regions. Is preferable. In particular, the intensity is 600 nm or more and 780 nm or less in the wavelength region between the peak having the highest peak intensity in the wavelength region of 495 nm or more and less than 600 nm or the peak having the highest peak intensity in the region of 600 nm or more and 780 nm or less. In terms of color clarity, it is preferable that there is a region that is 1/3 of the peak intensity of the peak having the highest peak intensity in the wavelength region.

The emission spectrum of the backlight source can be measured by using a spectroscope such as the Hamamatsu Photonics multi-channel spectroscope PMA-12.

(Polarizer)
Of the two polarizing plates arranged in the liquid crystal display device, at least one polarizing plate is made of polyester on at least one surface of a polarizing element obtained by dyeing polyvinyl alcohol (PVA) or the like with iodine via an adhesive layer. It is a laminated film. In the following, when the term "adhesive layer" is simply used, it means the adhesive layer existing between the polarizer and the polyester film. It is preferable that a film having no double refraction such as a TAC film, an acrylic film, or a norbornene-based film is laminated on the other surface of the polarizer (three-layered polarizing plate), but it is not always the same as that of the polarizer. It is not necessary for the film to be laminated on the other surface (two-layer polarizing plate). When a polyester film is used as the protective film on both sides of the polarizer, it is preferable that the slow axes of both polyester films are substantially parallel to each other.

As a result of diligent studies, the present inventions have peak tops in each wavelength region of 400 nm or more and less than 495 nm, 495 nm or more and less than 600 nm, and 600 nm or more and 780 nm or less, and have the highest peak intensity in the wavelength region of 600 nm or more and 780 nm or less. In a liquid crystal display device using a white light emitting diode having an emission spectrum having a high peak half-value width of less than 5 nm as a back light source, even when a polarizing plate using a polyester film is used as a polarizer protective film, the adhesive layer It has been found that if the difference between the refractive index and the refractive index of the polyester film in the direction parallel to the transmission axis of the polarizer is 0.13 or less, iris spots can be significantly suppressed. The mechanism by which the occurrence of iridescent color spots is suppressed by the above aspect is considered as follows.

When an oriented polyester film is arranged on one side of the polarizer, the polarization state of the linearly polarized light emitted from the backlight unit or the polarizer changes when passing through the polyester film. One of the factors that change the polarization state when the linearly polarized light emitted from the backlight unit or the polarizer passes through the oriented polyester film is the difference in the refractive index at the interface between the adhesive layer and the oriented polyester film. I found the possibility of When linearly polarized light incident from an oblique direction passes through each interface, a part of light is reflected due to the difference in refractive index between the interfaces. At this time, it is possible that the polarization state of both the emitted light and the reflected light changes, which is considered to be one of the factors that cause rainbow-shaped color spots. Therefore, by reducing the difference in refractive index between the adhesive and the oriented polyester film in the polarization direction (transmission axis direction) of the incident linearly polarized light, reflection at each interface is suppressed and rainbow-shaped color spots are formed. It is thought to be suppressed.

As described above, in the present invention, each wavelength region of the blue region (400 nm or more and less than 495 nm), the green region (495 nm or more and less than 600 nm), and the red region (600 nm or more and 780 nm or less) has a peak top of the emission spectrum. Polarization using a polyester film as a polarizer protective film in a liquid crystal display device using a white light emitting diode as a backlight source having a light emission spectrum having a relatively narrow peak half-value width (less than 5 nm) in the red region (600 nm or more and 780 nm or less). Even if a plate is used, it is possible to have good visibility without generating iridescent color spots.

The difference between the refractive index of the adhesive layer and the refractive index of the polyester film in the direction parallel to the transmission axis of the polarizer is preferably 0.13 or less, preferably 0.12 or less, preferably 0.11 or less. It is preferably 0.10 or less, preferably 0.9 or less, preferably 0.08 or less, preferably 0.07 or less, preferably 0.06 or less, and preferably 0.05 or less. The smaller the difference in refractive index, the more preferable it is because the reflection at the polyester film interface can be suppressed and the rainbow spots can be suppressed. The lower limit is 0.

The difference between the refractive index of the adhesive layer in the direction parallel to the transmission axis of the polarizer and the refractive index of the polyester film in the direction parallel to the transmission axis of the polarizer is more preferably 0.13 or less. It is preferably 0.12 or less, more preferably 0.11 or less, more preferably 0.10 or less, more preferably 0.09 or less, more preferably 0.08 or less, more preferably 0.07 or less, and more preferably. It is 0.06 or less, more preferably 0.05 or less. The smaller the difference in refractive index, the more preferable it is because the reflection at the polyester film interface can be suppressed and the rainbow spots can be suppressed. The lower limit is 0.

The method of laminating the polyester film and the polarizer is not particularly limited, and the phase advance axis direction of the polyester film and the transmission axis direction of the polarizer are substantially parallel, or the slow axis direction of the polyester film and the transducer transmission. An arrangement in which the axial directions are substantially parallel is preferable. Careful stacking may be performed so that the difference between the refractive index of the adhesive and the refractive index of the polyester film in the direction parallel to the transmission axis of the polarizer is within a preferable range.

Here, substantially parallel means that the angle formed by the transmission axis of the polarizer and the phase advance axis (or slow phase axis) of the polarizer protective film is preferably -15 ° to 15 °, more preferably -10 °. It means that it is -10 °, more preferably -5 ° to 5 °, even more preferably -3 ° to 3 °, still more preferably -2 ° to 2 °, and particularly preferably -1 ° to 1 °. In one preferred embodiment, substantially parallel is substantially parallel. Here, substantially parallel means that the transmission axis and the phase advance axis (or slow phase axis) are parallel to the extent that the displacement that inevitably occurs when the polarizer and the protective film are bonded to each other is allowed. Means. The direction of the slow axis can be determined by measuring with a molecular orientation meter (for example, MOA-6004 type molecular orientation meter manufactured by Oji Measuring Instruments Co., Ltd.).

(Polyester film)
The polyester film used for the polarizer protective film preferably has a retardation of 1500 to 30000 nm. If the retardation is within the above range, rainbow spots tend to be more easily reduced, which is preferable. The lower limit of the preferred retardation is 3000 nm, the next preferred lower limit is 3500 nm, the more preferred lower limit is 4000 nm, the more preferred lower limit is 6000 nm, and the further preferred lower limit is 8000 nm. The preferable upper limit is 30,000 nm, and a polyester film having a retardation of more than this tends to have a considerably large thickness and a decrease in handleability as an industrial material.

The retardation can be obtained by measuring the refractive index and the thickness in the biaxial direction, or can be obtained by using a commercially available automatic birefringence measuring device such as KOBRA-21ADH (Oji Measuring Instruments Co., Ltd.). The refractive index can be determined by an Abbe refractive index meter (measurement wavelength 589 nm).

The ratio (Re / Rth) of the retardation (Re: in-plane retardation) of the polyester film to the retardation (Rth) in the thickness direction is preferably 0.2 or more, more preferably 0.5 or more, still more preferably 0. 6 or more. The larger the ratio (Re / Rth) of the above retardation to the thickness direction retardation, the more isotropic the action of birefringence, and the less likely it is that iridescent color spots will occur depending on the observation angle. Since the ratio of the above retardation to the thickness direction retardation (Re / Rth) is 2.0 in a completely uniaxial (uniaxially symmetric) film, the ratio of the above retardation to the thickness direction retardation (Re / Rth) is The upper limit is preferably 2.0. The thickness direction phase difference means the average of the phase differences obtained by multiplying the two birefringence ΔNxz and ΔNyz when the film is viewed from the cross section in the thickness direction by the film thickness d, respectively.

The refractive index of the polyester film in the phase-advancing axis direction is preferably 1.53 or more and 1.62 or less. If the refractive index is less than 1.53, the crystallization of the polyester film becomes insufficient, and the properties obtained by stretching such as dimensional stability, mechanical strength, and chemical resistance become insufficient, which is not preferable. The upper limit of the refractive index of the polyester film in the phase-advancing axis direction is more preferably 1.61 or less, further preferably 1.60 or less, still more preferably 1.59 or less, and particularly preferably 1. It is 58 or less. The lower limit of the refractive index of the polyester film in the phase-advancing axis direction is more preferably 1.54 or more, further preferably 1.55 or more, still more preferably 1.56 or more, and particularly preferably 1. It is 57 or more.
The refractive index of the polyester film in the slow axis direction is preferably 1.67 or more and 1.75 or less. The upper limit of the refractive index of the polyester film in the slow axis direction is more preferably 1.74 or less, further preferably 1.73 or less, still more preferably 1.72 or less, and particularly preferably 1. It is 71 or less. The lower limit of the refractive index of the slow axis of the polyester film is more preferably 1.68 or more. The adjustment of the refractive index can be easily adjusted by a stretching treatment in a film forming step described later.

The polarizing element protective film made of the polyester film can be used for both the incident light side (light source side) and the emitted light side (visual recognition side). In the polarizing plate arranged on the incident light side, the polarizer protective film made of the polyester film is arranged on both sides regardless of whether the polarizing element is arranged on the incident light side or the liquid crystal cell side as a starting point. It may be arranged, but it is preferable that it is arranged at least on the incident light side. Regarding the polarizing plate arranged on the emitting light side, the polarizing element protective film made of the polyester film is arranged on both sides regardless of whether it is arranged on the liquid crystal side or the emitting light side with the polarizing element as the starting point. However, it is preferable that the film is arranged at least on the emitted light side.

As the polyester used for the polyester film, polyethylene terephthalate or polyethylene naphthalate can be used, but other copolymerization components may be contained. These resins are excellent in transparency as well as thermal and mechanical properties, and retardation can be easily controlled by stretching. In particular, polyethylene terephthalate has a large intrinsic birefringence, and by stretching the film, the refractive index in the phase-advancing axis (perpendicular to the slow-phase axis direction) can be suppressed to a low level, and it is relatively easy even if the film is thin. It is the most suitable material because it can obtain a large amount of retardation.

Further, for the purpose of suppressing deterioration of optical functional dyes such as iodine dyes, it is desirable that the polyester film has a light transmittance of 20% or less at a wavelength of 380 nm. The light transmittance at 380 nm is more preferably 15% or less, further preferably 10% or less, and particularly preferably 5% or less. When the light transmittance is 20% or less, deterioration of the optical functional dye due to ultraviolet rays can be suppressed. The transmittance is measured in a method perpendicular to the plane of the film, and can be measured using a spectrophotometer (for example, Hitachi U-3500 type).

In order to reduce the transmittance of the polyester film at a wavelength of 380 nm to 20% or less, it is desirable to appropriately adjust the type and concentration of the ultraviolet absorber and the thickness of the film. The UV absorber used in the present invention is a known substance. Examples of the ultraviolet absorber include an organic ultraviolet absorber and an inorganic ultraviolet absorber, but an organic ultraviolet absorber is preferable from the viewpoint of transparency. Examples of the organic ultraviolet absorber include benzotriazole-based, benzophenone-based, cyclic iminoester-based, and combinations thereof, but are not particularly limited as long as they are within the above-mentioned absorbance range. However, from the viewpoint of durability, benzotoazole-based and cyclic iminoester-based are particularly preferable. When two or more kinds of ultraviolet absorbers are used in combination, ultraviolet rays having different wavelengths can be absorbed at the same time, so that the ultraviolet absorption effect can be further improved.

Examples of benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and acrylonitrile-based ultraviolet absorbers include 2- [2'-hydroxy-5'-(methacryloyloxymethyl) phenyl] -2H-benzotriazole, 2- [2'. -Hydroxy-5'-(methacryloyloxyethyl) phenyl] -2H-benzotriazole, 2- [2'-hydroxy-5'-(methacryloyloxypropyl) phenyl] -2H-benzotriazole, 2,2'-dihydroxy- 4,4'-Dimethoxybenzophenone, 2,2', 4,4'-tetrahydroxybenzophenone, 2,4-di-tert-butyl-6- (5-chlorobenzotriazole-2-yl) phenol, 2- ( 2'-Hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (5-chloro (2H) -benzotriazole-2-yl) -4-methyl-6- ( Examples thereof include tert-butyl) phenol and 2,2′-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazole-2-yl) phenol). Examples of the ultraviolet absorbers include 2,2'-(1,4-phenylene) bis (4H-3,1-benzoxadinone-4-one) and 2-methyl-3,1-benzoxazine-4-one. , 2-Butyl-3,1-benzoxazine-4-one, 2-phenyl-3,1-benzoxazine-4-one and the like, but are not particularly limited thereto.

In addition to the ultraviolet absorber, it is also preferable to contain various additives other than the catalyst as long as the effects of the present invention are not impaired. As additives, for example, inorganic particles, heat-resistant polymer particles, alkali metal compounds, alkaline earth metal compounds, phosphorus compounds, antistatic agents, light-resistant agents, flame retardants, heat stabilizers, antioxidants, antigelling agents. , Surfactants and the like. Further, in order to obtain high transparency, it is also preferable that the polyester film contains substantially no particles. "Substantially free of particles" means, for example, in the case of inorganic particles, the content is 50 ppm or less, preferably 10 ppm or less, particularly preferably the detection limit or less when the inorganic element is quantified by Keiko X-ray analysis. means.

On the surface of the polyester film, which is a polarizing element protective film used in the present invention, various functional layers, that is, a hard coat layer, an antiglare layer, an antireflection layer, etc., are used for the purpose of preventing reflection, glare, and scratches. It is also a preferable mode to provide. When providing various functional layers, it is preferable that the polyester film has an easy-adhesion layer on its surface. At that time, from the viewpoint of suppressing interference due to reflected light, it is preferable to adjust the refractive index of the easy-adhesion layer so as to be close to the geometric mean of the refractive index of the functional layer and the refractive index of the polyester film. A known method can be adopted for adjusting the refractive index of the easy-adhesion layer. For example, the refractive index can be easily adjusted by adding titanium, germanium, or other metal species to the binder resin.

The polyester film can also be subjected to a corona treatment, a coating treatment, a flame treatment, or the like in order to improve the adhesiveness with the polarizer.

In the present invention, in order to improve the adhesiveness with the polarizer, an easy-adhesion layer containing at least one of polyester resin, polyurethane resin or polyacrylic resin as a main component is provided on at least one side of the film of the present invention. Is preferable. Here, the "main component" refers to a component that is 50% by mass or more of the solid components constituting the easy-adhesion layer. The coating liquid used for forming the easy-adhesion layer of the present invention is preferably an aqueous coating liquid containing at least one of a water-soluble or water-dispersible copolymerized polyester resin, an acrylic resin and a polyurethane resin. Examples of these coating solutions include water-soluble or water-dispersible copolymers disclosed in Japanese Patent No. 3567927, Japanese Patent No. 3589232, Japanese Patent No. 3589233, Japanese Patent No. 3900191, Japanese Patent No. 4150982, and the like. Examples thereof include a polymerized polyester resin solution, an acrylic resin solution, and a polyurethane resin solution.

The easy-adhesion layer can be obtained by applying the coating liquid to one or both sides of a uniaxially stretched film in the vertical direction, drying at 100 to 150 ° C., and further stretching in the horizontal direction. The final coating amount of the easy-adhesion layer is preferably controlled to ^{0.05 to 0.20 g / m 2.} If the coating amount is ^{less than 0.05 g / m 2} , the adhesiveness with the obtained polarizer may be insufficient. On the other hand, if the coating amount ^{exceeds 0.20 g / m 2} , the blocking resistance may decrease. When the easy-adhesion layers are provided on both sides of the polyester film, the coating amounts of the easy-adhesion layers on both sides may be the same or different, and can be independently set within the above ranges.

It is preferable to add particles to the easy-adhesion layer in order to impart slipperiness. It is preferable to use particles having an average particle size of 2 μm or less. When the average particle size of the particles exceeds 2 μm, the particles are likely to fall off from the coating layer. The particles contained in the easy-adhesion layer include, for example, titanium oxide, barium sulfate, calcium carbonate, calcium sulfate, silica, alumina, talc, kaolin, clay, calcium phosphate, mica, hectrite, zirconia, tungsten oxide, lithium fluoride, and the like. Examples thereof include inorganic particles such as calcium fluoride and organic polymer particles such as styrene-based, acrylic-based, melamine-based, benzoguanamine-based, and silicone-based particles. These may be added to the easy-adhesion layer alone, or may be added in combination of two or more.

Further, as a method of applying the coating liquid, a known method can be used. For example, the reverse roll coating method, the gravure coating method, the kiss coating method, the roll brush method, the spray coating method, the air knife coating method, the wire bar coating method, the pipe doctor method, etc. can be mentioned, and these methods can be used alone. Alternatively, it can be performed in combination.

The average particle size of the above particles is measured by the following method. The particles are photographed with a scanning electron microscope (SEM), and the maximum diameter of 300 to 500 particles (between the two most distant points) is magnified so that the size of one of the smallest particles is 2 to 5 mm. Distance) is measured, and the average value is taken as the average particle size.

The polyester film used as the polarizer protective film can be manufactured according to a general polyester film manufacturing method. For example, a non-oriented polyester obtained by melting a polyester resin and extruding it into a sheet is stretched in the vertical direction by utilizing the speed difference of rolls at a temperature equal to or higher than the glass transition temperature, and then stretched in the horizontal direction by a tenter. A method of applying heat treatment can be mentioned.

The polyester film used in the present invention may be a uniaxially stretched film or a biaxially stretched film, but when the biaxially stretched film is used as a polarizer protective film, it is observed from directly above the film surface. However, rainbow-shaped color spots are not seen, but it should be noted that rainbow-shaped color spots may be observed when observed from an oblique direction.

Specifically explaining the film forming conditions of the polyester film, the longitudinal stretching temperature and the transverse stretching temperature are preferably 80 to 135 ° C., more preferably 80 to 130 ° C., and particularly preferably 90 to 120 ° C. In order to orient the film so that the slow axis is in the TD direction, the longitudinal stretching ratio is preferably 1.0 to 3.5 times, particularly preferably 1.0 to 3.0 times. The lateral stretching ratio is preferably 2.5 to 6.0 times, particularly preferably 3.0 to 5.5 times. In order to orient the film so that the slow axis is in the MD direction, the longitudinal stretching ratio is preferably 2.5 to 6.0 times, particularly preferably 3.0 to 5.5 times. The transverse stretching ratio is preferably 1.0 to 3.5 times, and particularly preferably 1.0 to 3.0 times.
In order to control the refractive index or retardation of the polyester film in the phase-advancing axis direction within the above range, it is preferable to control the ratio of the longitudinal stretching ratio to the transverse stretching ratio. If the difference between the vertical and horizontal stretching ratios is too small, the refractive index of the polyester film in the phase-advancing axis direction tends to exceed 1.62, and it becomes difficult to increase the retardation, which is not preferable. Further, setting the stretching temperature low is a preferable measure for increasing the retardation. In the subsequent heat treatment, the treatment temperature is preferably 100 to 250 ° C, particularly preferably 180 to 245 ° C.

In order to suppress the fluctuation of retardation, it is preferable that the thickness unevenness of the film is small. Since the stretching temperature and the stretching ratio have a great influence on the thickness unevenness of the film, it is necessary to optimize the film forming conditions from the viewpoint of the thickness unevenness. In particular, if the longitudinal stretching ratio is lowered in order to increase the retardation, the vertical thickness unevenness may worsen. Since there is a region where the vertical thickness unevenness becomes very poor in a specific range of the draw ratio, it is desirable to set the film forming conditions outside this range.

The thickness unevenness of the polyester film is preferably 5.0% or less, more preferably 4.5% or less, still more preferably 4.0% or less, and more preferably 3.0% or less. Is particularly preferable.

As described above, in order to control the retardation of the polyester film within a specific range, it can be performed by appropriately setting the draw ratio, the draw temperature, and the thickness of the film. For example, the higher the stretching ratio, the lower the stretching temperature, and the thicker the film, the easier it is to obtain high retardation. On the contrary, the lower the stretching ratio, the higher the stretching temperature, and the thinner the film, the easier it is to obtain low retardation. However, when the thickness of the film is increased, the phase difference in the thickness direction tends to increase. Therefore, it is desirable to appropriately set the film thickness within the range described later. Further, in addition to the control of retardation, it is necessary to set the final film forming conditions in consideration of the physical characteristics required for processing.

The thickness of the polyester film is arbitrary, but is preferably in the range of 15 to 300 μm, more preferably in the range of 15 to 200 μm. In principle, it is possible to obtain retardation of 1500 nm or more even with a film having a thickness of less than 15 μm. However, in that case, the anisotropy of the mechanical properties of the film becomes remarkable, and tearing, tearing, etc. are likely to occur, and the practicality as an industrial material is remarkably lowered. A particularly preferable lower limit of the thickness is 25 μm. On the other hand, if the upper limit of the thickness of the polarizing element protective film exceeds 300 μm, the thickness of the polarizing plate becomes too thick, which is not preferable. From the viewpoint of practicality as a polarizer protective film, the upper limit of the thickness is preferably 200 μm. A particularly preferable upper limit of the thickness is 100 μm, which is equivalent to that of a general TAC film. In order to control the retardation within the range of the present invention even in the above thickness range, polyethylene sauce phthalate is preferable as the polyester used as the film base material.

Further, as a method of blending an ultraviolet absorber into a polyester film, a known method can be used in combination. For example, a master batch is prepared by blending a dried ultraviolet absorber and a polymer raw material using a kneading extruder in advance. It can be prepared and blended by a method of mixing the predetermined masterbatch with the polymer raw material at the time of film formation.

At this time, the concentration of the ultraviolet absorber in the masterbatch is preferably 5 to 30% by mass in order to uniformly disperse the ultraviolet absorber and to blend it economically. As a condition for producing the masterbatch, it is preferable to use a kneading extruder and extrude the polyester raw material at a temperature equal to or higher than the melting point of the polyester raw material and lower than 290 ° C. for 1 to 15 minutes. At 290 ° C. or higher, the amount of the ultraviolet absorber is greatly reduced, and the viscosity of the masterbatch is significantly reduced. If the extrusion temperature is 1 minute or less, it becomes difficult to uniformly mix the ultraviolet absorber. At this time, a stabilizer, a color tone adjusting agent, and an antistatic agent may be added as needed.

Further, it is preferable that the polyester film has a multilayer structure of at least three layers or more, and an ultraviolet absorber is added to the intermediate layer of the film. Specifically, a film having a three-layer structure containing an ultraviolet absorber in the intermediate layer can be produced as follows. A polyester pellet alone for the outer layer, and a masterbatch containing an ultraviolet absorber for the intermediate layer and polyester pellets are mixed at a predetermined ratio, dried, and then supplied to a known hot-dip laminating extruder to form a slit. It is extruded from a die into a sheet and cooled and solidified on a casting roll to form an unstretched film. That is, using two or more extruders, a three-layer manifold or a merging block (for example, a merging block having a square merging portion), the film layers constituting both outer layers and the film layers constituting the intermediate layer are laminated. A three-layer sheet is extruded from the base and cooled with a casting roll to make an unstretched film. In the present invention, in order to remove foreign substances contained in the raw material polyester, which causes optical defects, it is preferable to perform high-precision filtration at the time of melt extrusion. The filter particle size (initial filtration efficiency 95%) of the filter medium used for high-precision filtration of the molten resin is preferably 15 μm or less. If the filtered particle size of the filter medium exceeds 15 μm, the removal of foreign matter of 20 μm or more tends to be insufficient.

(Adhesive layer)
As the adhesive for adhering the polyester film and the polarizer, conventionally known adhesives can be used. The lower limit of the refractive index of the adhesive layer is preferably 1.46 or more, more preferably 1.47 or more, still more preferably 1.48 or more. The upper limit of the refractive index of the adhesive layer is preferably 1.59 or less, more preferably 1.56 or less, still more preferably 1.54 or less.

Examples of the adhesive include polyvinyl alcohol-based adhesives such as polyvinyl alcohol and polyvinyl butyral, and conventionally known water-based adhesives such as vinyl latex such as polybutyl acrylate. The polyvinyl alcohol-based adhesive includes polyvinyl alcohol, partially saponified polyvinyl acetate, polyvinyl alcohol modified with a carboxyl group or an acetoacetyl group, polyvinyl alcohol treated with formalization, and the like.

A cross-linking agent may be added to the water-based adhesive. The cross-linking agent is not particularly limited, and a known cross-linking agent can be used. For example, those used for polyvinyl alcohol-based adhesives can be used without particular limitation. For example, alkylenediamines having two alkylene groups and two amino groups such as ethylenediamine, triethylenediamine and hexamethylenediamine; tolylene diisocyanate, hydrogenated tolylene diisocyanate, trimethylolpropane tolylene diisocyanate adduct, triphenylmethane triisocyanate, methylenebis. (4-Phenylmethane triisocyanate), isophorone diisocyanates and isocyanates such as these ketooxime blocks or phenol blocks; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerinji or triglycidyl ether, 1,6- Epoxys such as hexanediol diglycidyl ether, trimethylpropan triglycidyl ether, diglycidylaniline, diglycidylamine; monoaldehydes such as formaldehyde, acetaldehyde, propionaldehyde, butylaldehyde; glioxal, malondialdehyde, succindialdehyde, Dialdehydes such as glutalurdialdehyde, maleindialdehyde, and phthaldialdehyde; amino-formaldehyde resins such as methylol urea, methylol melamine, alkylated methylol urea, alkylated methylolated melamine, acetguanamine, and condensates of benzoguanamine and formaldehyde. Zyrazine compounds such as zirconium acetate, zirconium nitrate, zirconium carbonate, zirconium hydroxide, zirconium hydrochloride; metal glycylic acid salts (metals include alkali metals such as lithium, sodium and potassium, and alkaline soils such as magnesium and calcium. Kinds of metals, titanium, zirconium, chromium, manganese, iron, cobalt, nickel, transition metals such as copper, zinc, aluminum, etc.), glyoxylate amine salts (amines include, for example, ammonia, monomethylamine, dimethyl). Glyoxyphosphates such as amines, trimethylamines, etc .); amino acids or sulfur-containing amino acids having one or more basic groups and one or more acidic groups; dimethoxyethaneal, diethoxyethanal, dialkoxyethane. Acetal compounds such as nal; further, divalent metals such as sodium, potassium, magnesium, calcium, aluminum, iron and nickel, or salts of trivalent metals and oxides thereof can be exemplified. These may be used alone or in combination of two or more. Among these, it is preferable to use an amino acid having one or more basic groups and one or more acidic groups, or a sulfur-containing amino acid. The basic group is preferably an amino group, and the acidic group is preferably a carboxyl group or a sulfo group. Examples of the amino acids include glycine, alanine, phenylalanine, valine, leucine, isoleucine, lysine, proline, serine, threonine, tryptophan, histidine, tyrosine, arginine, asparagine, aspartic acid, aspartate, glutamine, glutamic acid, and these amino acids. Examples thereof include a copolymer with (meth) acrylic acid. Examples of the sulfur-containing amino acid include methionine, cysteine, cystine, taurine and the like. Among these, it is particularly preferable to use a sulfur-containing amino acid having a sulfo group such as taurine. Those using a metal salt can increase the refractive index of the adhesive layer. Further, as the cross-linking agent, a coupling agent such as a silane coupling agent or a titanium coupling agent can be used. When 100 parts by mass of a polyvinyl alcohol-based resin such as polyvinyl alcohol and polyvinyl butyral or a vinyl-based latex such as polybutyl acrylate is used as the blending amount of the cross-linking agent, for example, 0.1 to 50 parts by mass is preferable and more preferable. Is 0.2 to 30 parts by mass, more preferably 0.5 to 20 parts by mass.

In addition, in recent years, an active energy ray-curable adhesive is also preferable. The polarizing plate has a structure in which a polarizing element protective film is laminated on both sides of the polarizer, and it is preferable that at least one of the polarizing element protective films is laminated with the polarizer via an active energy ray-curable adhesive. By using the active energy ray-curable composition, adhesion can be achieved even when a low moisture permeable film is used, and adhesion can be improved. Further, it is possible to improve the environmental resistance such as the moisture and heat resistance of the polarizing plate. In particular, by using the solvent-free active energy ray-curable resin composition, the step of drying the adhesive becomes unnecessary, so that the productivity can be improved.

As the active energy ray-curable compound contained in the active energy ray-curable composition, conventionally known compounds can be used. Specifically, in addition to the epoxy compound and the oxetane compound, a radically polymerizable monomer such as a (meth) acrylate compound can be used.

(Epoxy compound and oxetane compound)
Epoxy compounds include alicyclic epoxy compounds, glycidyl etherified compounds of aromatic compounds and chain compounds having hydroxyl groups, glycidyl aminated compounds of compounds having amino groups, and epoxy compounds of chain compounds having CC double bonds. Examples include compounds.

Here, the alicyclic epoxy compound refers to a compound having an epoxy group directly on the ring of the saturated cyclic compound and a compound having a glycidyl ether group or a glycidyl group directly on the ring of the saturated cyclic compound. In addition, another epoxy group may be included in the structure.

An alicyclic epoxy compound having an epoxy group directly on the ring of a saturated cyclic compound is a base of a CC double bond of a cyclic compound having a CC double bond on the ring, using a peroxide. It is obtained by epoxidation under sexual conditions.

The cyclic compound having a CC double bond in the ring is not particularly limited, and examples thereof include a compound having a cyclopentene ring, a compound having a cyclohexene ring, and a polycyclic compound thereof. Cyclic compounds having a CC double bond in the ring may have a CC double bond outside the ring, and such compounds include, for example, 1-vinyl-3-cyclohexene and monoterpene. Examples include limonene, which is a type monoterpene.

Further, the alicyclic epoxy compound having an epoxy group directly on the ring of the saturated cyclic compound may be a compound having a structure in which the epoxide obtained as described above is quantified via an appropriate functional group. The bond structure composed of the functional group is not particularly limited, and examples thereof include an ester bond, an ether bond, and a bond with an alkyl group. Further, the dimerized structure of the epoxidized product may have a plurality of these bonds.

The method for producing an alicyclic epoxy compound having an epoxy group directly on the ring of the saturated cyclic compound varies depending on the individual compound and is not particularly limited. A method of synthesizing a cyclic compound having a heavy bond in a ring and then epoxidizing the compound, and a compound having an epoxidized CC double bond further reacted with a functional group as described above to obtain a target structure. A method of synthesizing or the like is adopted. From the viewpoint of suppressing side reactions of epoxy groups, a method of synthesizing a cyclic compound having a CC double bond in a ring and then epoxidizing is usually preferably adopted.

The synthesis of the cyclic compound having a CC double bond in the ring varies depending on the skeleton of the target epoxy compound and is not particularly limited, but as an example of the synthesis of the quantified cyclic compound, For example, a method of obtaining 3-cyclohexenylmethyl-3-cyclohexene carboxylate, which is an ester compound, from 3-cyclohexene-1-carboxyaldehyde by a Tishchenko reaction using an appropriate catalyst can be mentioned.

Further, an ester exchange reaction between the ester compound and a dicarboxylic acid compound or an ester thereof, a diol compound or an ester thereof, a polyalkylene glycol or an ester thereof, or a hydroxycarboxylic acid compound or an ester thereof, if necessary, using a catalyst. By doing so, a compound having a cyclohexenyl group at both ends can be obtained.

Examples of the dicarboxylic acid compound and its ester include oxalic acid, adipic acid, and sebacic acid, and dimethyl esters thereof. Examples of the diol compound and its ester include ethylene glycol, diethylene glycol, 1,2-propanediol, polyethylene glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, and dimethyl esters thereof. Can be mentioned. Examples of the hydroxycarboxylic acid compound and its ester include lactic acid, 3-hydroxybutyric acid, citric acid, dimethyl ester and acetate thereof, and lactide, propiolactone, butyrolactone, and caprolactone. ..

The cyclic compound having a CC double bond in the ring thus obtained is epoxidized with a peroxide to obtain an alicyclic epoxy compound having an epoxy group directly on the ring of the saturated cyclic compound. be able to. The peroxide is selected according to the individual cyclic compound, acceptable reaction conditions, etc., and is not particularly limited, but is, for example, hydrogen peroxide, peracetic acid, and t-butyl hydroperoxide. And so on.

Specific examples of the alicyclic epoxy compound having an epoxy group directly on the ring of the saturated cyclic compound include, for example, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, 1,2-epoxy-. 4-vinylcyclohexane, 1,2-epoxy-1-methyl-4- (1-methylepoxyethyl) cyclohexane, 3,4-epoxycyclohexylmethylmethacrylate, 2,2-bis (hydroxymethyl)-1-butanol 4- (1,2-epoxyethyl) -1,2-epoxycyclohexane adduct, ethylene bis (3,4-epoxycyclohexanecarboxylate), oxydiethylene bis (3,4-epoxycyclohexanecarboxylate), 1,4 -Cyclohexanedimethylbis (3,4-epoxycyclohexanecarboxylate), 3- (3,4-epoxycyclohexylmethoxycarbonyl) propyl 3,4-epoxycyclohexanecarboxylate and the like can be mentioned.

The alicyclic epoxy compound having a glycidyl ether group or a glycidyl group directly on the ring of the saturated cyclic compound is an aromatic ring of an aromatic compound having a hydroxyl group, which will be described later, under pressure in the presence of a catalyst. Refers to a compound obtained by selectively carrying out a hydrogenation reaction in (1), a glycidyl ether compound of a saturated cyclic compound having a hydroxyl group, and an epoxidized compound of a saturated cyclic compound having a vinyl group.

The glycidyl etherified product of the aromatic compound having a hydrogenated hydroxyl group is not particularly limited, but for example, the glycidyl etherified product of bisphenol A and its oligomer, and the glycidyl etherified product of bisphenol F and its oligomer. The body etc. can be mentioned.

The glycidyl ether compound of the saturated cyclic compound having a hydroxyl group is not particularly limited, and examples thereof include 1,4-cyclohexanedimethanol diglycidyl ether.

The epoxidized product of the saturated cyclic compound having a vinyl group is not particularly limited, and is, for example, 1,3-bis (epoxyethyl) hexane, 1,2,4-tris (epoxyethyl) hexane, and 2. , 4-Bis (epoxyethyl) -1-vinylcyclohexane and the like.

Among the above-mentioned alicyclic epoxy compounds, 3,4-epoxy is available because it exhibits good cured product properties in improving the durability of the polarizing plate, has appropriate curability, and can be obtained at a relatively low price. Hydrochlorides of cyclohexylmethyl 3,4-epoxycyclohexanecarboxylate and glycidyl etherified bisphenol A are preferred, with 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate being more preferred.

Further, these alicyclic epoxy compounds may be used alone or in combination of two or more.

The hue of the active energy ray-curable composition containing the alicyclic epoxy compound is preferably 5 or less, more preferably 3 or less, still more preferably 1 or less, in terms of Gardner chromaticity of the active energy ray-curable composition before curing. If the hue exceeds 5, the hue of the polarizing plate may be affected by the coloring of the adhesive layer.

The glycidyl etherified product of an aromatic compound having a hydroxyl group and a chain compound is obtained by addition-condensing a compound such as epichlorohydrin to the hydroxyl group under alkaline conditions. For example, a bisphenol type epoxy resin, a polyaromatic ring type epoxy resin, an alkylene glycol type epoxy resin and the like can be mentioned.

Examples of the bisphenol type epoxy resin include glycidyl etherified product of bisphenol A and its oligomer, glycidyl etherified product of bisphenol F and its oligomer, and 3,3', 5,5'-methyl-4,4'-biphenol. Examples thereof include glycidyl etherified products and oligomers thereof.

Examples of the polyaromatic ring-type epoxy resin include a glycidyl etherified product of a phenol novolac resin, a glycidyl etherified product of a cresol novolac resin, a glycidyl etherified product of a phenol aralkyl resin, a glycidyl etherified product of a naphthol aralkyl resin, and a phenol dicyclopentadiene. Examples thereof include glycidyl etherified resin. Further, a glycidyl etherified product of trihydroxyphenylmethane and an oligomer thereof, a glycidyl etherified product of trihydroxyphenyl PA and an oligomer thereof, and the like can be mentioned.

Examples of the alkylene glycol type epoxy resin include glycidyl etherified product of ethylene glycol, glycidyl etherified product of diethylene glycol, glycidyl etherified product of 1,4-butanediol, and glycidyl etherified product of 1,6-hexanediol. Be done.

The glycidyl aminated compound of a compound having an amino group is obtained by addition-condensing a compound such as epichlorohydrin to the amino group under basic conditions. The compound having an amino group may have a hydroxyl group at the same time. For example, glycidyl amination of 1,3-phenylenediamine and its oligomers, glycidyl amination of 1,4-phenylenediamine and its oligomers, glycidyl amination of 3-aminophenol and glycidyl etherified products and their oligomers. , And glycidyl amination of 4-aminophenol, glycidyl etherified product, and oligomers thereof.

An epoxide of a chain compound having a CC double bond is an epoxide of a CC double bond of a chain compound having a CC double bond using a peroxide under basic conditions. It is obtained by letting it.

The chain compound having a CC double bond is not particularly limited, and examples thereof include butadiene, polybutadiene, isoprene, pentadiene, and hexadiene.

These epoxy compounds and their oligomers may be used alone or in combination of two or more.

Commercially available products of such epoxy compounds are easily available. For example, the trade names are "Ceroxide", "Cyclomer" (all manufactured by Dicell Chemical Industries, Ltd.) and "Syracure" (Syracure). Dow Chemical Co., Ltd.), "Epicort" (manufactured by Japan Epoxy Resin Co., Ltd.), "Epicron" (manufactured by DIC Corporation), "Epototo" (manufactured by Toto Kasei Co., Ltd.), "Adeca Resin" (manufactured by ADEKA Co., Ltd.), " Examples include "Denacol" (manufactured by Nagase ChemteX Corporation), "Dow Epoxy" (manufactured by Dow Chemical Co., Ltd.) and "Tepic" (manufactured by Nissan Chemical Industry Co., Ltd.).

The epoxy equivalent of the epoxy compound is usually 30 to 2000 g / eq, preferably 50 to 1500 g / eq, and more preferably 70 to 1000 g / eq. If the epoxy equivalent is less than 30 g / eq, the flexibility of the first adhesive layer may decrease or the adhesive strength may decrease. On the other hand, if it exceeds 2000 g / eq, the curing rate may decrease, or the rigidity and strength required for the cured adhesive layer may be insufficient. This epoxy equivalent is a value measured in accordance with JIS K 7236 (ISO 3001). If the epoxy compound is a high-purity monomer, the theoretical amount can be calculated from its molecular weight.

As the active energy ray-curable compound, by using a plurality of epoxy compounds, for example, an alicyclic epoxy compound and an epoxy compound other than the alicyclic epoxy compound in combination, the adhesion between the polarizing film and the stretched polyester film can be improved. Can be improved.

As the active energy ray-curable compound, an oxetane compound can be used. The oxetane compound can improve the curing rate of the active energy ray-curable composition. The oxetane compound is a compound having an oxetane ring and is not particularly limited as long as it is active energy ray-curable, but for example, 1,4-bis {[(3-ethyloxetane-3-yl)). Methoxy] methyl} benzene, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, bis (3-ethyl-3-oxetanylmethyl) ether, 3-ethyl-3- (phenoxymethyl) oxetane, 3-ethyl Examples thereof include -3- (cyclohexyloxymethyl) oxetane, phenol novolac oxetane, and 1,3-bis [(3-ethyloxetane-3-yl) methoxy] benzene.

Commercially available products of such oxetane compounds are easily available. For example, "Aron Oxetane" (manufactured by Toagosei Co., Ltd.) and "ETERNACOLL" (manufactured by Ube Industries, Ltd.) are available under the trade names, respectively. And so on.

The active energy ray-curable composition containing an epoxy compound or an oxetane compound is preferably blended with a cationic polymerization initiator in order to be cured by the active energy rays. The cationic polymerization initiator generates a cationic species or Lewis acid by irradiation with active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams, and initiates a polymerization reaction of an epoxy group and an oxetane.

It is preferable that the cationic polymerization initiator has a potential. The addition of potential prolongs the pot life of the active energy ray-curable composition used in the present invention and improves workability.

The compound that produces a cationic species or Lewis acid by irradiation with active energy rays is not particularly limited, and is, for example, an aromatic diazonium salt, an aromatic iodonium salt, an onium salt such as an aromatic sulfonium salt, and iron. -Allen complex and the like can be mentioned.

Examples of the aromatic diazonium salt include benzenediazonium hexafluoroantimonate, benzenediazonium hexafluorophosphate, and benzenediazonium hexafluoroborate.

Examples of the aromatic iodonium salt include diphenyliodonium tetrakis (pentafluorophenyl) borate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, and di (4-nonylphenyl) iodonium hexafluorophosphate.

Examples of the aromatic sulfonium salt include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, and diphenyl [4- (phenylthio) phenyl] sulfonium hexafluoroantimonate. 4,4'-bis [diphenylsulfonio] diphenylsulfide bishexafluorophosphate, 4,4'-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenylsulfide bishexafluoroantimonate, 4,4'-bis [Di (β-hydroxyethoxy) phenylsulfonium] diphenylsulfide bishexafluorophosphate, 7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate, 7- [di (p-toluyl) sulfonium ] -2-Isopropylthioxanthone tetrakis (pentafluorophenyl) borate, 4-phenylcarbonyl-4'-diphenylsulfonio-diphenylsulfide hexafluorophosphate, 4- (p-tert-butylphenylcarbonyl) -4'-diphenylsulfonio -Diphenylsulfide Hexafluoroantimonate, 4- (p-tert-butylphenylcarbonyl) -4'-di (p-toluyl) sulfonio-diphenylsulfide tetrakis (pentafluorophenyl) borate and the like can be mentioned.

Examples of the iron-allene complex include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, and xylene-cyclopentadienyl iron (II)-. Tris (trifluoromethylsulfonyl) metanide and the like can be mentioned.

These cationic polymerization initiators may be used alone or in combination of two or more. Among them, aromatic sulfonium salts are particularly preferably used because they have ultraviolet absorption characteristics even in a wavelength region of 300 nm or more, and thus can provide a cured product layer having excellent curability and good mechanical strength and adhesive strength. ..

The blending amount of the cationic polymerization initiator is usually 0.5 to 20 parts by weight, preferably 1 to 15 parts by weight, based on 100 parts by weight of the total active energy ray-curable compound. If the amount is less than 0.5 parts by weight, the curing becomes insufficient, and the mechanical strength and the adhesive strength of the cured product layer may decrease. On the other hand, if the amount exceeds 20 parts by weight, the amount of ionic substances in the cured product layer increases, so that the hygroscopicity of the cured product layer increases, and the durability performance of the obtained polarizing plate may decrease.

Commercially available products of these cationic polymerization initiators are easily available. For example, the trade names are "Kayarad" (manufactured by Nippon Kayaku Co., Ltd.), "Syracure" (manufactured by Union Carbide), and so on. Photoacid generator "CPI" (manufactured by Sun Appro Co., Ltd.), photoacid generator "TAZ", "BBI", "DTS" (manufactured by Midori Chemical Co., Ltd.), "ADEKA PUTMER" (manufactured by ADEKA Corporation) , And "RHODORSIL" (manufactured by Rhodia).

(Radical polymerizable monomer such as (meth) acrylate compound)
Examples of the radically polymerizable monomer include an acrylate compound, a methacrylate compound (hereinafter, also referred to as (meth) acrylate in the sense that both acrylate and methacrylate are included), an allyl urethane compound, an unsaturated polyester compound, and a styrene compound. Be done. (Meta) acrylate is preferable because it is easily available and easy to handle. Examples of (meth) acrylates include epoxy (meth) acrylates, urethane (meth) acrylates, (poly) ester (meth) acrylates, (poly) ether (meth) acrylates, alcoholic (meth) acrylates, and other (meth) acrylates. Acrylate can be mentioned.

The epoxy (meth) acrylate exemplified as the above (meth) acrylate compound is one or more kinds of epoxy resins and acrylic acid or methacrylic acid (hereinafter, also referred to as (meth) acrylic acid in the sense of including both). It is an ester compound with. Here, the epoxy resin for inducing the ester is not particularly limited, and one having one or more epoxy groups in the molecule, such as an aromatic epoxy resin, an alicyclic epoxy resin, an aliphatic epoxy resin, and an epoxy novolak resin. Can be used.

The urethane (meth) acrylate contains a hydroxyl group which is an ester compound of one or more kinds of (poly) ester polyols, (poly) ether polyols, polyhydric alcohols and the like and (meth) acrylic acid. A (meth) acrylate obtained by reacting a meta) acrylate with one or more (poly) isocyanate compounds; one or more (poly) ester polyols, (poly) ether polyols, many. It is an ester compound having a urethane bond, such as (meth) acrylate obtained by reacting a polyol such as a valent alcohol with a hydroxyl group-containing (meth) acrylate and isocyanates.

Examples of the polyhydric alcohol that induces (poly) ester polyol include 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, neopentyl glycol, polyethylene glycol, and polypropylene. Glycol, polybutylene glycol, trimethylolpropane, glycerin, pentaerythritol, dipentaerythritol and the like can be mentioned. Examples of the polycarboxylic acid that induces the (poly) ester polyol include adipic acid, terephthalic acid, phthalic anhydride, trimellitic acid, and trimesic acid.

Examples of the (poly) ether polyol include those obtained by adding an alkylene oxide such as ethylene oxide, propylene oxide, or butylene oxide to the above-mentioned polyhydric alcohol. Examples of the (poly) isocyanate compound include monovalent or divalent or higher valent isocyanates, and divalent or higher valent isocyanates are preferable.

Examples of divalent or higher valent isocyanates include 2,4- and / or 2,6-tolylene diisocyanate, diphenylmethane-4,4'-diisocyanate, p-phenylenediocyanate, xylylene diisocyanate, 1,5-naphthylene diisocyanate, and 3 , 3'-Dimethyldiphenyl-4,4'-diisocyanate, dianisidine diisocyanate, tetramethylxylylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, trans and / or cis-1,4-cyclohexanediisocyanate, Norbornen diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4 and / or (2,4,4) -trimethylhexamethylene diisocyanate, lysine diisocyanate, triphenylmethane triisocyanate, 1-methylbenzol-2,4 Examples thereof include 6-triisocyanate and dimethyltriphenylmethanetetraisocyanate.

The (poly) ester (meth) acrylate is an ester compound of a (poly) ester having one or more hydroxyl groups in the molecule and a (meth) acrylic acid. As a (poly) ester having one or more hydroxyl groups in the molecule, an ester compound of one or more polyhydric alcohols and one or more monocarboxylic acids or polycarboxylic acids. Can be mentioned.

Examples of the polyvalent alcohol for inducing a (poly) ester having one or more hydroxyl groups in the molecule include the same compounds as those described above, and examples of the monocarboxylic acid include formic acid, acetic acid, and propionic acid. , Butyric acid, isobutyric acid, valeric acid, caproic acid, caprylic acid, 2-ethylhexanoic acid, benzoic acid and the like. Examples of the polycarboxylic acid include the same as those of the above-mentioned compounds.

Further, the (poly) ether (meth) acrylate is an ester compound of (poly) ether having one or more hydroxyl groups in the molecule and (meth) acrylic acid. As the (poly) ether having one or more hydroxyl groups in the molecule, one or more alkylene oxides are added to 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, and polyhydric alcohol. Examples include those obtained by doing so. Examples of the polyhydric alcohol and the alkylene oxide include the same compounds as those described above. Specifically, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, ethylene oxide-modified trimethylolpropane tri (meth) acrylate, propylene. Examples thereof include oxide-modified trimethylolpropane tri (meth) acrylate and dipentaerythritol hexa (meth) acrylate.

The (meth) acrylate of alcohols is an ester compound of an alcohol (particularly an aliphatic alcohol or an aromatic alcohol) having one or more hydroxyl groups in the molecule and the (meth) acrylate. For example, 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, isoamyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, isooctyl (meth). Acrylate, tetrahydrofurfuryl (meth) acrylate, isobonyl (meth) acrylate, benzyl (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, neopentyl glycol di Examples thereof include (meth) acrylate, 1,6-hexanediol di (meth) acrylate, trimethylpropantri (meth) acrylate, and pentaerythritol tetra (meth) acrylate.

Examples of other acrylates include ε-caprolactone-modified dipentaerythritol hexa (meth) acrylate, fluorene derivative di (meth) acrylate, and carbazole derivative di (meth) acrylate.

The radically polymerizable monomer described above can be used to control the curing rate. When a radically polymerizable monomer is used, at least a photoradical polymerization initiator is used.

Examples of the photoradical polymerization initiator include ketone compounds such as acetophenone compounds, benzyl compounds, benzophenone compounds, and thioxanthone compounds.

Examples of the acetophenone compound include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 4'-isopropyl-2-hydroxy-2-methylpropiophenone, and 2-hydroxymethyl-. 2-Methylpropiophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, p-dimethylaminoacetonone, P-tershalibutyldichloroacetophenone, p-tershaributyltrichloroacetophenone, p-azidoben Zaracetophenone, 1-hydroxycyclohexylphenylketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropanone-1, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) ) -Butanone-1, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether and the like, and examples of the benzyl-based compound include benzyl, anisyl and the like, and benzophenone-based. Examples of the compound include benzophenone, methyl o-benzoyl benzoate, Michler ketone, 4,4'-bisdiethylaminobenzophenone, 4,4'-dichlorobenzophenone, 4-benzoyl-4'-methyldiphenylsulfide and the like, and thioxanthone. Examples of the system compound include thioxanthone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, 2,4-diethylthioxanthone and the like.

One or more of these photoradical polymerization initiators can be blended and used according to desired performance, and preferably 0.05 to 10% by mass with respect to the radically polymerizable monomer. , More preferably 0.1 to 10% by mass. When the blending amount of the photoradical polymerization initiator with respect to the radically polymerizable monomer is 0.05% by mass or more, the curing of the photocurable adhesive can proceed more satisfactorily, and when it is 10% by mass or less, light The physical strength of the adhesive layer formed by curing the curable adhesive is good.

The total amount of chlorine contained in the active energy ray-curable composition is preferably in the range of 0.1 ppm to 15000 ppm, more preferably in the range of 0.5 ppm to 2000 ppm, and even more preferably in the range of 1.0 to 1000 ppm. If the total amount of chlorine contained in the active energy ray-curable composition is less than 0.1 ppm, the curing rate of the composition may become extremely slow. On the other hand, if it exceeds 15,000 ppm, the coating device may be corroded or the metal parts of the liquid crystal panel may be corroded due to the influence of chlorine. The total amount of chlorine is a value measured in accordance with JIS K 7243-3 (ISO 21627-3).

Examples of the active energy rays used include X-rays having a wavelength of 1 pm to 10 nm, ultraviolet rays having a wavelength of 10 to 400 nm, and visible light having a wavelength of 400 to 800 nm. Among them, ultraviolet rays are preferably used in terms of ease of use, ease of adjustment of the active energy ray-curable composition and its stability, and its curing performance.

The active energy ray-curable composition used in the present invention is a curable composition that is solidified (cured) by irradiation with active energy rays and imparts adhesive force to films sandwiching the cured product layer.

The light source used is not particularly limited, but for example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a chemical lamp, a black light lamp, and a microwave-excited mercury lamp having an emission distribution at a wavelength of 400 nm or less. And metal halide lamps and the like.

The irradiation intensity is determined by the active energy ray-curable composition and the irradiation time, and is not particularly limited. For example, the irradiation intensity in the wavelength region effective for activating the initiator is 0.1. It is preferably ~ 1000 mW / cm ^2. If the light irradiation intensity of the active energy ray-curable composition is ^{less than 0.1 mW / cm 2} , the curing reaction time becomes long, that is, the active energy ray-curable composition is not cured unless a long irradiation time is taken, which is disadvantageous for improving productivity. In some cases. If it exceeds 1000 mW / cm ² , the heat radiated from the lamp and the heat generated during the polymerization of the active energy ray-curable composition may cause yellowing of the active energy ray-curable composition or deterioration of the polarizing film. There is.

The irradiation time is determined by the active energy ray-curable composition and the irradiation intensity, and is not particularly limited. For example, the integrated light amount expressed as the product of the irradiation intensity and the irradiation time is 10 to 5. It is preferably set to 000 mJ / cm ^2. If the integrated light amount to the active energy ray-curable composition is ^{less than 10 mJ / cm 2} , the generation of the active species derived from the initiator may not be sufficient, and the resulting adhesive layer may be insufficiently cured. Further, if it exceeds 5,000 mJ / cm ² , the irradiation time becomes very long, which may be disadvantageous in improving productivity.

The active energy ray-curable composition used in the present invention can be used in combination with a photosensitizer, if necessary. By using the photosensitizer, the reactivity can be improved, and the mechanical strength and the adhesive strength of the cured product layer can be improved.

The photosensitizer is not particularly limited, and examples thereof include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, and photoreducing dyes. ..

Carbonyl compounds include, for example, benzoin methyl ether, benzoin isopropyl ether, and benzoin derivatives such as α, α-dimethoxy-α-phenylacetophenone; anthracene compounds such as 9,10-dibutoxyanthracene; benzophenone, 2,4. Benzophenone derivatives such as -dichlorobenzophenone, methyl o-benzoylbenzoate, 4,4'-bis (dimethylamino) benzophenone, and 4,4'-bis (diethylamino) benzophenone; of 2-chloroanthraquinone and 2-methylanthraquinone. Such anthraquinone derivatives; acridone derivatives such as N-methylacridone and N-butylacridone; acetophenone derivatives such as α, α-diethoxyacetophenone; xanthone derivatives; and fluorenone derivatives and the like.

Examples of the organic sulfur compound include thioxanthone derivatives such as 2-chlorothioxanthone and 2-isopropylthioxanthone. Other examples include benzyl compounds and uranyl compounds.

The photosensitizers may be used alone or in combination. The photosensitizer is preferably contained in the range of 0.1 to 20 parts by weight when the active energy ray-curable composition is 100 parts by weight.

Various additives can be added to the active energy ray-curable composition used in the present invention as long as the effects of the present invention are not impaired. Examples of various additives include ion trapping agents, antioxidants, chain transfer agents, sensitizers, tackifiers, thermoplastic resins, fillers, flow regulators, plasticizers, defoamers and the like. Be done.

Examples of the ion trapping agent include powdered bismuth-based, antimony-based, magnesium-based, aluminum-based, calcium-based, titanium-based, and inorganic compounds such as a mixture thereof. Examples of the antioxidant include a hindered phenolic antioxidant and the like.

Examples of the thermoplastic resin include acrylic resin, urethane resin, polyester resin and the like.

The method for forming the layer (adhesive layer before curing) composed of the active energy ray-curable composition shown above on the polarizing film or the polarizer protective film is not particularly limited, but for example, the polarizing film. Alternatively, a method of coating the composition on the polarizing element protective film, a method of spraying the composition, a method of laminating the composition previously formed in the form of a film, or the like is adopted. Among them, the method of applying the composition or the method of laminating the film-like composition is preferable because the uniformity of the coating film is relatively high, and the method of applying the composition is relatively high in productivity. preferable.

The coating method is not particularly limited, but various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater are adopted.

The thickness of the coated adhesive layer before curing is usually 0.1 to 20 μm, preferably 0.2 to 10 μm, and more preferably 0.5 to 5 μm. If the thickness is less than 0.1 μm, the adhesive force between the polarizing film and the polarizer protective film due to the cured adhesive layer may be insufficient. Further, if the thickness exceeds 20 μm, the adhesive layer may not be sufficiently cured, or even if the adhesive layer is cured, the flexibility of the film may be deteriorated due to the thickness, or the effect of thinning may not be obtained. ..

The thickness of the adhesive layer is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 3 μm or less. The lower limit is preferably 5 nm or more, more preferably 10 nm or more, and even more preferably 20 nm or more.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by the following Examples, and is carried out with appropriate modifications to the extent that it can be adapted to the gist of the present invention. It is also possible, all of which are within the technical scope of the invention. The method for evaluating the physical properties in the following examples is as follows.

(1) Refractive rate of polyester film Using a molecular orientation meter (MOA-6004 type molecular orientation meter manufactured by Oji Measuring Instruments Co., Ltd.), determine the slow axis direction of the film, and the slow axis direction is the long side of the sample for measurement. A rectangle of 4 cm × 2 cm was cut out so as to be parallel to the above, and used as a measurement sample. For this sample, the refractive indexes of the two orthogonal axes (refractive index in the slow axis direction: Ny, refractive index in the phase advance axis (refractive index in the direction orthogonal to the slow axis direction): Nx), and the refractive index in the thickness direction ( Nz) was determined by an Abbe refractive index meter (manufactured by Atago Co., Ltd., NAR-4T, measurement wavelength 589 nm).

(2) Reference (Re)
The retardation is a parameter defined by the product (ΔNxy × d) of the anisotropy of the refractive indexes of the two orthogonal axes on the film (ΔNxy = | Nx−Ny |) and the film thickness d (nm). Yes, it is a scale showing optical isotropic and anisotropy. The biaxial refractive index anisotropy (ΔNxy) was determined by the following method. Using a molecular orientation meter (MOA-6004 type molecular orientation meter manufactured by Oji Measuring Instruments Co., Ltd.), determine the slow-phase axial direction of the film, and 4 cm so that the slow-phase axial direction is parallel to the long side of the measurement sample. A rectangle of × 2 cm was cut out and used as a measurement sample. For this sample, the refractive index of two orthogonal axes (refractive index in the slow axis direction: Ny, refractive index in the direction orthogonal to the slow axis direction: Nx), and the refractive index in the thickness direction (Nz) are abbe refraction. It was determined by a rate meter (manufactured by Atago Co., Ltd., NAR-4T, measurement wavelength 589 nm), and the absolute value (| Nx-Ny |) of the difference in refractive index between the two axes was defined as the anisotropy of the refractive index (ΔNxy). The film thickness d (nm) was measured using an electric micrometer (Millitron 1245D, manufactured by Finereuf), and the unit was converted to nm. The retardation (Re) was determined from the product (ΔNxy × d) of the anisotropy of the refractive index (ΔNxy) and the thickness d (nm) of the film.

(3) Thickness direction retardation (Rth)
The thickness direction retardation is obtained by multiplying two birefringences ΔNxz (= | Nx−Nz |) and ΔNyz (= | Ny−Nz |) when viewed from a cross section in the film thickness direction by the film thickness d, respectively. It is a parameter indicating the average of the refraction obtained. Nx, Ny, Nz and the film thickness d (nm) are obtained by the same method as the measurement of retardation, and the average value of (ΔNxz × d) and (ΔNyz × d) is calculated to calculate the thickness direction retardation (Rth). ) Was asked.

(4) Measurement of Emission Spectrum of Backlight Light Source REGZA 43J10X manufactured by Toshiba Corporation was used as the liquid crystal display device used in each example. When the emission spectrum of the backlight source (white light emitting diode) of this liquid crystal display device was measured using a multi-channel spectroscope PMA-12 manufactured by Hamamatsu Photonics, an emission spectrum having peak tops near 450 nm, 535 nm, and 630 nm was observed. Was done. The half width of each peak top (half width of the peak having the highest peak intensity in each wavelength region) was 17 nm for the peak at 450 nm and 45 nm for the peak at 535 nm and 2 nm for the peak at 630 nm, respectively. This light source had a plurality of peaks in the wavelength region of 600 nm or more and 780 nm or less, and the half width was evaluated at the peak near 630 nm, which has the highest peak intensity in this region. The exposure time for spectrum measurement was 20 msec.

(5) Observation of rainbow spots The liquid crystal display devices obtained in each example were visually observed in a dark place from the front and diagonal directions, and the presence or absence of rainbow spots was determined as follows.

◯: No rainbow spots are observed △: Slight rainbow spots are observed ×: Rainbow spots are observed × ×: Rainbow spots are significantly observed

(6) Refractive Index of Adhesive Layer After applying the adhesive to the glass plate, it was solidified under the same conditions as the actual processing to prepare a coating film of about several μm. The coating film was peeled off from the glass plate, and the refractive index was measured with an Abbe refractometer (NAR-1T SOLID manufactured by Atago Co., Ltd., measurement wavelength 589 nm).

(Production Example 1-Polyester A)
When the temperature of the esterification reaction can was raised to 200 ° C., 86.4 parts by mass of terephthalic acid and 64.6 parts by mass of ethylene glycol were charged, and 0.017 parts by mass of antimony trioxide was used as a catalyst while stirring. 0.064 parts by mass of magnesium acetate tetrahydrate and 0.16 parts by mass of triethylamine were charged. Then, the pressure was raised and the pressure esterification reaction was carried out under the conditions of a gauge pressure of 0.34 MPa and 240 ° C., the esterification reaction can was returned to normal pressure, and 0.014 parts by mass of phosphoric acid was added. Further, the temperature was raised to 260 ° C. over 15 minutes, and 0.012 parts by mass of trimethyl phosphate was added. Then, after 15 minutes, dispersion treatment was carried out with a high-pressure disperser, and after 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reaction can, and a polycondensation reaction was carried out under reduced pressure at 280 ° C.

After completion of the polycondensation reaction, filtration is performed with a Naslon filter having a 95% cut diameter of 5 μm, extruded into a strand shape from a nozzle, and cooled and solidified using cooling water that has been previously filtered (pore diameter: 1 μm or less). , Cut into pellets. The intrinsic viscosity of the obtained polyethylene terephthalate resin (A) was 0.62 dl / g, and it contained substantially no inert particles and internally precipitated particles. (Hereafter, it is abbreviated as PET (A).)

(Production Example 2-Polyester B)
10 parts by mass of dried UV absorber (2,2'-(1,4-phenylene) bis (4H-3,1-benzoxadinone-4-one), particle-free PET (A) (intrinsic viscosity) 0.62 dl / g) 90 parts by mass was mixed, and a polyethylene terephthalate resin (B) containing an ultraviolet absorber was obtained using a kneading extruder (hereinafter abbreviated as PET (B)).

(Manufacturing Example 3-Adhesive Modification Coating Liquid Adjustment)
Transesterification and polycondensation reactions were carried out by a conventional method to obtain 46 mol% of terephthalic acid, 46 mol% of isophthalic acid and 8 mol% of sodium 5-sulfonatoisophthalate as dicarboxylic acid components (relative to the entire dicarboxylic acid component). A water-dispersible metal sulfonate metal-base-containing polycondensation polyester resin having a composition of 50 mol% ethylene glycol and 50 mol% neopentyl glycol as the glycol component was prepared. Next, 51.4 parts by mass of water, 38 parts by mass of isopropyl alcohol, 5 parts by mass of n-butyl cell solution, and 0.06 parts by mass of a nonionic surfactant were mixed, and then heated and stirred. After adding 5 parts by mass of a water-dispersible metal sulfonic acid base-containing copolymerized polyester resin and continuing to stir until the resin is no longer clumped, the resin aqueous dispersion is cooled to room temperature to have a solid content concentration of 5.0% by mass. A uniform water-dispersible copolymerized polyester resin liquid was obtained. Further, after 3 parts by mass of aggregate silica particles (Syricia 310 manufactured by Fuji Silicia Co., Ltd.) were dispersed in 50 parts by mass of water, 99.46 parts by mass of the water-dispersible copolymerized polyester resin liquid was added to Syricia 310. 0.54 parts by mass of an aqueous dispersion was added, and 20 parts by mass of water was added with stirring to obtain an adhesive modification coating liquid.

(Polarizer protective film 1)
After 90 parts by mass of PET (A) resin pellets containing no particles and 10 parts by mass of PET (B) resin pellets containing an ultraviolet absorber were dried under reduced pressure (1 Torr) at 135 ° C. for 6 hours as raw materials for the base film intermediate layer. , It was supplied to the extruder 2 (for the intermediate layer II layer), and the PET (A) was dried by a conventional method and supplied to the extruder 1 (for the outer layer I layer and the outer layer III), respectively, and melted at 285 ° C. .. These two types of polymers are filtered through a stainless steel sintered filter medium (nominal filtration accuracy of 10 μm particles 95% cut), laminated in a two-type three-layer confluence block, extruded into a sheet from the base, and then extruded. Using the electrostatic application casting method, the film was wound around a casting drum having a surface temperature of 30 ° C. and cooled and solidified to prepare an unstretched film. At this time, the discharge amount of each extruder was adjusted so that the ratio of the thicknesses of the I layer, the II layer, and the III layer was 10:80:10.

Next, the adhesive modification coating liquid was applied to both sides of the unstretched PET film by the reverse roll method ^{so that the coating amount after drying was 0.08 g / m 2} , and then dried at 80 ° C. for 20 seconds. ..

The unstretched film on which the coating layer was formed was guided to a tenter stretching machine, and while gripping the end of the film with a clip, it was guided to a hot air zone having a temperature of 125 ° C. and stretched 4.0 times in the width direction. Next, while maintaining the width stretched in the width direction, the film was treated at a temperature of 225 ° C. for 10 seconds, and further subjected to a relaxation treatment of 3.0% in the width direction to obtain a uniaxially stretched PET film having a film thickness of about 100 μm. rice field. The Re of the obtained film was 10300 nm, Rth was 12350 nm, Re / Rth was 0.83, Nx = 1.588, and Ny = 1.691.

(Polarizer protective film 2)
A film was formed in the same manner as the polarizer protective film 1 except that the line speed was changed to change the thickness of the unstretched film, and a uniaxially stretched PET film having a film thickness of about 80 μm was obtained. The Re of the obtained film was 8080 nm, Rth was 9960 nm, Re / Rth was 0.81, Nx = 1.589, and Ny = 1.690.

(Polarizer protective film 3)
A film was formed in the same manner as the polarizer protective film 1 except that the line speed was changed to change the thickness of the unstretched film, and a uniaxially stretched PET film having a film thickness of about 60 μm was obtained. The Re of the obtained film was 6060 nm, Rth was 7470 nm, Re / Rth was 0.81, Nx = 1.589, and Ny = 1.690.

(Polarizer protective film 4)
A film was formed in the same manner as the polarizer protective film 1 except that the line speed was changed to change the thickness of the unstretched film, and a uniaxially stretched PET film having a film thickness of about 40 μm was obtained. The Re of the obtained film was 4160 nm, the Rth was 4920 nm, the Re / Rth was 0.85, Nx = 1.587, and Ny = 1.691.

(Polarizer protective film 5)
The unstretched film produced by the same method as the polarizer protective film 1 is heated to 105 ° C. using a heated roll group and an infrared heater, and then 1.5 in the traveling direction in the roll group having a peripheral speed difference. After double stretching, the film was guided to a hot air zone at a temperature of 130 ° C. and stretched 4.0 times in the width direction to obtain a biaxially stretched PET film having a film thickness of about 100 μm in the same manner as in the polarizer protective film 1. The Re of the obtained film was 7820 nm, the Rth was 13890 nm, the Re / Rth was 0.56, Nx = 1.608, and Ny = 1.686.

(Polarizer protective film 6)
The unstretched film produced by the same method as the polarizer protective film 1 is heated to 105 ° C. using a heated roll group and an infrared heater, and then 2.0 in the traveling direction in the roll group having a peripheral speed difference. After double-stretching, the film was guided to a hot air zone at a temperature of 135 ° C. and stretched 4.0 times in the width direction to obtain a biaxially stretched PET film having a film thickness of about 100 μm in the same manner as the polarizer protective film 1. The Re of the obtained film was 6400 nm, the Rth was 14600 nm, the Re / Rth was 0.44, Nx = 1.617, and Ny = 1.681.

(Polarizer protective film 7)
The unstretched film produced by the same method as the polarizer protective film 1 is heated to 105 ° C. using a heated roll group and an infrared heater, and then 2.8 in the traveling direction in the roll group having a peripheral speed difference. After double stretching, the film was guided to a hot air zone at a temperature of 140 ° C. and stretched 4.0 times in the width direction to obtain a biaxially stretched PET film having a film thickness of about 100 μm in the same manner as in the polarizer protective film 1. The Re of the obtained film was 5400 nm, the Rth was 15900 nm, the Re / Rth was 0.34, Nx = 1.631, and Ny = 1.685.

(Polarizer protective film 8)
The unstretched film produced by the same method as the polarizer protective film 1 is heated to 105 ° C. using a heated roll group and an infrared heater, and then 3.3 in the traveling direction in the roll group having a peripheral speed difference. After double stretching, the film was guided to a hot air zone at a temperature of 140 ° C. and stretched 4.0 times in the width direction to obtain a biaxially stretched PET film having a film thickness of about 100 μm in the same manner as in the polarizer protective film 1. The Re of the obtained film was 4800 nm, Rth was 16700 nm, Re / Rth was 0.29, Nx = 1.640, and Ny = 1.688.

A liquid crystal display device was created using the polarizer protective films 1 to 8 as described later.

(Example 1)
A polarizing element protective film 1 is attached to one side of a polarizer composed of PVA and iodine so that the transmission axis of the polarizer and the phase advance axis of the film are parallel to each other, and TAC film (Fuji Film Co., Ltd.) is attached to the opposite surface. The polarizing plate 1 was prepared by pasting (manufactured by 80 μm in thickness). The polarizer, the polarizer protective film, and the TAC film were bonded together via an aqueous solution (polyvinyl alcohol-based adhesive) consisting of 4 parts of polyvinyl alcohol, 1 part of melamine, and 95 parts of water, and dried at 60 ° C. for 3 minutes. The refractive index of this polyvinyl alcohol-based adhesive was 1.490.
A liquid crystal display device was created by replacing the polarizing plate on the visible side of REGZA 43J10X manufactured by Toshiba with the above polarizing plate 1 so that the polyester film was on the opposite side (distal) to the liquid crystal. The direction of the transmission axis of the polarizing plate 1 was replaced so as to be the same as the direction of the transmission axis of the polarizing plate before the replacement.

(Example 2)
A polarizing element protective film 2 is attached to one side of a polarizer composed of PVA and iodine so that the transmission axis of the polarizer and the phase advance axis of the film are parallel to each other, and TAC film (Fuji Film Co., Ltd.) is attached to the opposite surface. The polarizing plate 2 was prepared by pasting (manufactured by 80 μm in thickness). The polarizer, the polarizer protective film, and the TAC film were bonded together via an aqueous solution (polyvinyl alcohol-based adhesive) consisting of 4 parts of polyvinyl alcohol, 1 part of melamine, and 95 parts of water, and dried at 60 ° C. for 3 minutes. The refractive index of this polyvinyl alcohol-based adhesive was 1.490.
A liquid crystal display device was produced in the same manner as in Example 1 except that the polarizing plate 1 was changed to the polarizing plate 2.

(Example 3)
A polarizing element protective film 3 is attached to one side of a polarizer composed of PVA and iodine so that the transmission axis of the polarizer and the phase advance axis of the film are parallel to each other, and TAC film (Fuji Film Co., Ltd.) is attached to the opposite surface. The polarizing plate 3 was prepared by pasting (manufactured by 80 μm in thickness). The polarizer, the polarizer protective film, and the TAC film were bonded together via an aqueous solution (polyvinyl alcohol-based adhesive) consisting of 4 parts of polyvinyl alcohol, 1 part of melamine, and 95 parts of water, and dried at 60 ° C. for 3 minutes. The refractive index of this polyvinyl alcohol-based adhesive was 1.490.
A liquid crystal display device was produced in the same manner as in Example 1 except that the polarizing plate 1 was changed to the polarizing plate 3.

(Example 4)
A polarizing element protective film 3 is attached to one side of a polarizer composed of PVA and iodine so that the transmission axis of the polarizer and the phase advance axis of the film are parallel to each other, and TAC film (Fuji Film Co., Ltd.) is attached to the opposite surface. The polarizing plate 3 was prepared by pasting (manufactured by 80 μm in thickness). The polarizer, the polarizer protective film, and the TAC film were bonded together via an aqueous solution (polyvinyl alcohol-based adhesive) consisting of 4 parts of polyvinyl alcohol, 1 part of melamine, and 95 parts of water, and dried at 60 ° C. for 3 minutes. The refractive index of this polyvinyl alcohol-based adhesive was 1.490.
A liquid crystal display device was created by replacing the polarizing plate on the light source side of REGZA 43J10X manufactured by Toshiba with the above polarizing plate 3 so that the polyester film is on the opposite side (distal) to the liquid crystal. The direction of the transmission axis of the polarizing plate 3 was replaced so as to be the same as the direction of the transmission axis of the polarizing plate before the replacement.

(Example 5)
A polarizing element protective film 3 is attached to one side of a polarizer composed of PVA and iodine so that the transmission axis of the polarizer and the phase advance axis of the film are parallel to each other, and TAC film (Fuji Film Co., Ltd.) is attached to the opposite surface. The polarizing plate 3 was prepared by pasting (manufactured by 80 μm in thickness). The polarizer, the polarizer protective film, and the TAC film were bonded together via an aqueous solution (polyvinyl alcohol-based adhesive) consisting of 4 parts of polyvinyl alcohol, 1 part of melamine, and 95 parts of water, and dried at 60 ° C. for 3 minutes. The refractive index of this polyvinyl alcohol-based adhesive was 1.490.
A liquid crystal display device was created by replacing the polarizing plates on the visual side and the light source side of REGZA 43J10X manufactured by Toshiba with the above polarizing plate 3 so that the polyester film was on the opposite side (distal) to the liquid crystal. The direction of the transmission axis of the polarizing plate 3 was replaced so as to be the same as the direction of the transmission axis of the polarizing plate before the replacement.

(Example 6)
A polarizing element protective film 4 is attached to one side of a polarizer composed of PVA and iodine so that the transmission axis of the polarizer and the phase advance axis of the film are parallel to each other, and TAC film (Fuji Film Co., Ltd.) is attached to the opposite surface. The polarizing plate 4 was prepared by pasting (manufactured by 80 μm in thickness). The polarizer, the polarizer protective film, and the TAC film were bonded together via an aqueous solution (polyvinyl alcohol-based adhesive) consisting of 4 parts of polyvinyl alcohol, 1 part of melamine, and 95 parts of water, and dried at 60 ° C. for 3 minutes. The refractive index of this polyvinyl alcohol-based adhesive was 1.490.
A liquid crystal display device was produced in the same manner as in Example 1 except that the polarizing plate 1 was changed to the polarizing plate 4.

(Example 7)
A polarizing element protective film 5 is attached to one side of a polarizer composed of PVA and iodine so that the transmission axis of the polarizer and the phase advance axis of the film are parallel to each other, and TAC film (Fuji Film Co., Ltd.) is attached to the opposite surface. A polarizing plate 5 was prepared by pasting (manufactured by 80 μm in thickness). The polarizer, the polarizer protective film, and the TAC film were bonded together via an aqueous solution (polyvinyl alcohol-based adhesive) consisting of 4 parts of polyvinyl alcohol, 1 part of melamine, and 95 parts of water, and dried at 60 ° C. for 3 minutes. The refractive index of this polyvinyl alcohol-based adhesive was 1.490.
A liquid crystal display device was produced in the same manner as in Example 1 except that the polarizing plate 1 was changed to the polarizing plate 5.

(Example 8)
A polarizing element protective film 6 is attached to one side of a polarizer composed of PVA and iodine so that the transmission axis of the polarizer and the phase advance axis of the film are parallel to each other, and TAC film (Fuji Film Co., Ltd.) is attached to the opposite surface. A polarizing plate 6 was prepared by pasting (manufactured by 80 μm in thickness). The polarizer, the polarizer protective film, and the TAC film were bonded together via an aqueous solution (polyvinyl alcohol-based adhesive) consisting of 4 parts of polyvinyl alcohol, 1 part of melamine, and 95 parts of water, and dried at 60 ° C. for 3 minutes. The refractive index of this polyvinyl alcohol-based adhesive was 1.490.
A liquid crystal display device was produced in the same manner as in Example 1 except that the polarizing plate 1 was changed to the polarizing plate 6.

(Comparative Example 1)
A polarizing element protective film 1 is attached to one side of a polarizer composed of PVA and iodine so that the transmission axis of the polarizer and the phase advance axis of the film are perpendicular to each other, and TAC film (Fuji Film Co., Ltd.) is attached to the opposite surface. A polarizing plate 7 was prepared by pasting (manufactured by 80 μm in thickness). The polarizer, the polarizer protective film, and the TAC film were bonded together via an aqueous solution (polyvinyl alcohol-based adhesive) consisting of 4 parts of polyvinyl alcohol, 1 part of melamine, and 95 parts of water, and dried at 60 ° C. for 3 minutes. The refractive index of this polyvinyl alcohol-based adhesive was 1.490.
A liquid crystal display device was created by replacing the polarizing plate on the visible side of REGZA 43J10X manufactured by Toshiba with the above polarizing plate 7 so that the polyester film was on the opposite side (distal) to the liquid crystal. The direction of the transmission axis of the polarizing plate 7 was replaced so as to be the same as the direction of the transmission axis of the polarizing plate before replacement.

(Comparative Example 2)
A polarizing element protective film 2 is attached to one side of a polarizer composed of PVA and iodine so that the transmission axis of the polarizer and the phase advance axis of the film are perpendicular to each other, and TAC film (Fuji Film Co., Ltd.) is attached to the opposite surface. A polarizing plate 8 was prepared by pasting (manufactured by 80 μm in thickness). The polarizer, the polarizer protective film, and the TAC film were bonded together via an aqueous solution (polyvinyl alcohol-based adhesive) consisting of 4 parts of polyvinyl alcohol, 1 part of melamine, and 95 parts of water, and dried at 60 ° C. for 3 minutes. The refractive index of this polyvinyl alcohol-based adhesive was 1.490.
A liquid crystal display device was produced in the same manner as in Comparative Example 1 except that the polarizing plate 7 was changed to the polarizing plate 8.

(Comparative Example 3)
A polarizing element protective film 3 is attached to one side of a polarizer composed of PVA and iodine so that the transmission axis of the polarizer and the phase advance axis of the film are perpendicular to each other, and TAC film (Fuji Film Co., Ltd.) is attached to the opposite surface. A polarizing plate 9 was prepared by pasting (manufactured by 80 μm in thickness). The polarizer, the polarizer protective film, and the TAC film were bonded together via an aqueous solution (polyvinyl alcohol-based adhesive) consisting of 4 parts of polyvinyl alcohol, 1 part of melamine, and 95 parts of water, and dried at 60 ° C. for 3 minutes. The refractive index of this polyvinyl alcohol-based adhesive was 1.490.
A liquid crystal display device was produced in the same manner as in Comparative Example 1 except that the polarizing plate 7 was changed to the polarizing plate 9.

(Comparative Example 4)
A polarizing element protective film 3 is attached to one side of a polarizer composed of PVA and iodine so that the transmission axis of the polarizer and the phase advance axis of the film are perpendicular to each other, and TAC film (Fuji Film Co., Ltd.) is attached to the opposite surface. A polarizing plate 9 was prepared by pasting (manufactured by 80 μm in thickness). The polarizer, the polarizer protective film, and the TAC film were bonded together via an aqueous solution (polyvinyl alcohol-based adhesive) consisting of 4 parts of polyvinyl alcohol, 1 part of melamine, and 95 parts of water, and dried at 60 ° C. for 3 minutes. The refractive index of this polyvinyl alcohol-based adhesive was 1.490.
A liquid crystal display device was created by replacing the polarizing plate on the light source side of REGZA 43J10X manufactured by Toshiba with the above polarizing plate 9 so that the polyester film is on the opposite side (distal) to the liquid crystal. The direction of the transmission axis of the polarizing plate 9 was replaced so as to be the same as the direction of the transmission axis of the polarizing plate before replacement.

(Comparative Example 5)
A polarizing element protective film 3 is attached to one side of a polarizer composed of PVA and iodine so that the transmission axis of the polarizer and the phase advance axis of the film are perpendicular to each other, and TAC film (Fuji Film Co., Ltd.) is attached to the opposite surface. A polarizing plate 9 was prepared by pasting (manufactured by 80 μm in thickness). The polarizer, the polarizer protective film, and the TAC film were bonded together via an aqueous solution (polyvinyl alcohol-based adhesive) consisting of 4 parts of polyvinyl alcohol, 1 part of melamine, and 95 parts of water, and dried at 60 ° C. for 3 minutes. The refractive index of this polyvinyl alcohol-based adhesive was 1.490.
A liquid crystal display device was created by replacing the polarizing plates on the visual side and the light source side of REGZA 43J10X manufactured by Toshiba with the above polarizing plate 9 so that the polyester film was on the opposite side (distal) to the liquid crystal. The direction of the transmission axis of the polarizing plate 9 was replaced so as to be the same as the direction of the transmission axis of the polarizing plate before replacement.

(Comparative Example 6)
A polarizing element protective film 4 is attached to one side of a polarizer composed of PVA and iodine so that the transmission axis of the polarizer and the phase advance axis of the film are perpendicular to each other, and TAC film (Fuji Film Co., Ltd.) is attached to the opposite surface. The polarizing plate 10 was prepared by pasting (manufactured by 80 μm in thickness). The polarizer, the polarizer protective film, and the TAC film were bonded together via an aqueous solution (polyvinyl alcohol-based adhesive) consisting of 4 parts of polyvinyl alcohol, 1 part of melamine, and 95 parts of water, and dried at 60 ° C. for 3 minutes. The refractive index of this polyvinyl alcohol-based adhesive was 1.490.
A liquid crystal display device was produced in the same manner as in Comparative Example 1 except that the polarizing plate 7 was changed to the polarizing plate 10.

(Comparative Example 7)
A polarizing element protective film 7 is attached to one side of a polarizer composed of PVA and iodine so that the transmission axis of the polarizer and the phase advance axis of the film are parallel to each other, and TAC film (Fuji Film Co., Ltd.) is attached to the opposite surface. The polarizing plate 11 was prepared by pasting (manufactured by 80 μm in thickness). The polarizer, the polarizer protective film, and the TAC film were bonded together via an aqueous solution (polyvinyl alcohol-based adhesive) consisting of 4 parts of polyvinyl alcohol, 1 part of melamine, and 95 parts of water, and dried at 60 ° C. for 3 minutes. The refractive index of this polyvinyl alcohol-based adhesive was 1.490.
A liquid crystal display device was produced in the same manner as in Comparative Example 1 except that the polarizing plate 7 was changed to the polarizing plate 11.

(Comparative Example 8)
A polarizing element protective film 8 is attached to one side of a polarizer composed of PVA and iodine so that the transmission axis of the polarizer and the phase advance axis of the film are parallel to each other, and TAC film (Fuji Film Co., Ltd.) is attached to the opposite surface. The polarizing plate 12 was prepared by pasting (manufactured by 80 μm in thickness). The polarizer, the polarizer protective film, and the TAC film were bonded together via an aqueous solution (polyvinyl alcohol-based adhesive) consisting of 4 parts of polyvinyl alcohol, 1 part of melamine, and 95 parts of water, and dried at 60 ° C. for 3 minutes. The refractive index of this polyvinyl alcohol-based adhesive was 1.490.
A liquid crystal display device was produced in the same manner as in Comparative Example 1 except that the polarizing plate 7 was changed to the polarizing plate 12.

The results of measuring the rainbow spot observation for the liquid crystal display device obtained in each example are shown in Table 1 below.

The liquid crystal display device and the polarizing plate of the present invention can ensure good visibility in which the occurrence of rainbow-shaped color spots is significantly suppressed at any observation angle, and have extremely high industrial applicability. ..

Claims (2)

A liquid crystal display device having a backlight light source, two polarizing plates, and a liquid crystal cell arranged between the two polarizing plates.
The backlight source has a peak top of the emission spectrum in each wavelength region of 400 nm or more and less than 495 nm, 495 nm or more and less than 600 nm, and 600 nm or more and 780 nm or less, and has the highest peak intensity in the wavelength region of 600 nm or more and 780 nm or less. A white light emitting diode having an emission spectrum with a peak width of less than 5 nm.
At least one of the two polarizing plates is obtained by laminating a polyester film on at least one surface of the polarizing element via an adhesive layer.
The refractive index of the adhesive layer, Ri difference 0.13 der following the refractive index of the polyester film in the transmission direction parallel to the axis of the polarizer,
The polyester film has an in-plane retardation of 1500 to 30000 nm.
Liquid crystal display device. In the emission spectrum of the backlight source, the half width of the peak having the highest peak intensity in the wavelength region of 400 nm or more and less than 495 nm is 5 nm or more, and the half width of the peak having the highest peak intensity in the wavelength region of 495 nm or more and less than 600 nm is. The liquid crystal display device according to claim 1, which has a wavelength of 5 nm or more.