TWI790203B - Liquid crystal display device - Google Patents

Abstract

The present invention provides a liquid crystal display device with peaks of luminescent spectra in the wavelength ranges of 400nm to 495nm, 495nm to 600nm, and 600nm to 780nm. When using an alignment film as a polarizer protective film, it can also A liquid crystal display device that suppresses rainbow spots.

A liquid crystal display device, which is a liquid crystal display device with a backlight source, a light source side polarizer, a liquid crystal cell, and a recognition side polarizer; wherein the backlight source is between 400nm and less than 495nm, between 495nm and less than 600nm, and between 600nm and 780nm Each wavelength region has a peak top of the luminescent spectrum, and the half-maximum width of each peak is more than 5nm; the identification side polarizer includes a polyester film A with a retardation of 1500-30000nm, and at least one area layer of the polyester film A Anti-reflection layer and/or low-reflection layer; the polarizing plate on the light source side includes polyester film B; when the retardation of polyester film B is determined as Re _B , the peaks in the wavelength region of 600nm to 780nm of the backlight source will be present When the wavelength of the peak top is defined as Rx, and the half-width is defined as Ry, Ry/[Rx/(Re _B /Rx)] is 0.55 or more.

Description

Liquid crystal display device

The invention relates to a liquid crystal display device. Specifically, it relates to a liquid crystal display device that reduces the occurrence of iridescent color spots.

Polarizers used in liquid crystal displays (LCD) generally have a structure in which a polarizer dyed with iodine such as polyvinyl alcohol (PVA) is sandwiched between two polarizer protective films, and as a polarizer protective film, in many cases The system uses triacetyl cellulose (TAC) film. In recent years, along with the thinning of LCDs, thinning of polarizing plates is required. However, if the thickness of the TAC film used as a protective film is reduced, sufficient mechanical strength cannot be obtained, and a problem arises in that moisture permeability deteriorates. Also, TAC films are very expensive, and polyester films have been proposed as inexpensive alternative materials (Patent Documents 1 to 3), but there is a problem that iridescent spots are observed.

When a birefringent oriented polyester film is arranged on one side of the polarizer, when the linearly polarized light emitted from the backlight unit or the polarizer passes through the polyester film, the polarization state changes. The retardation of the transmitted light at the product of birefringence and thickness of the aligned polyester film exhibits characteristic interference colors. Therefore, if a discontinuous luminescence spectrum such as a cold cathode tube or a hot cathode tube is used as the If it is a light source, different transmitted light intensities are displayed depending on the wavelength, and it becomes an iridescent color spot (reference: Proceedings of the 15th Micro Optical Conference, items 30~31).

As a means to solve the above-mentioned problems, someone proposes to use a white light source such as a white light-emitting diode that is continuous and has a broad luminous spectrum as a backlight source, and uses an aligned polyester film with a certain delay as a polarizer protective film (patent Document 4). White light-emitting diode with a continuous and broad emission spectrum in the visible light region. Therefore, it has been proposed that if one pays attention to the envelope shape of the interference color spectrum caused by the transmitted light of the birefringent body, by controlling the retardation of the aligned polyester film, a spectrum similar to the luminescence spectrum of the light source can be obtained, and the spectrum can be suppressed. rainbow spots.

By making the alignment direction of the aligned polyester film and the polarization direction of the polarizer be perpendicular or parallel to each other, the linearly polarized light emitted from the polarizer can pass through the aligned polyester film while maintaining the polarized state. In addition, by controlling the birefringence of the oriented polyester film, the uniaxial alignment is improved, and the light incident from an oblique direction can also pass through while maintaining the polarized state. When the aligned polyester film is viewed obliquely, the direction of the main axis of alignment deviates compared to when viewed from directly above, but if the uniaxial alignment is high, the deviation of the main axis direction of the alignment when viewed obliquely becomes smaller. Therefore, the deviation between the direction of the linearly polarized light and the direction of the main axis of alignment becomes smaller, and the change of the polarization state becomes less likely to occur. As mentioned above, by controlling the light emission spectrum of the light source, the alignment state of the birefringent body, and the direction of the main axis of alignment, the change of the polarization state can be suppressed, iridescent color spots will not occur, and the visibility is significantly improved.

prior art literature patent documents

Patent Document 1 Japanese Patent Laid-Open No. 2002-116320

Patent Document 2 Japanese Patent Laid-Open No. 2004-219620

Patent Document 3 Japanese Patent Laid-Open No. 2004-205773

Patent Document 4 WO2011/162198

When using a polarizing plate using a polyester film as a polarizer protective film to industrially produce a liquid crystal display device, it is usually arranged such that the transmission axis of the polarizer and the fast axis of the polyester film are perpendicular to each other. The foregoing is due to the following circumstances. The polyvinyl alcohol film of the polarizer is produced by longitudinal uniaxial stretching. Therefore, the polyvinyl alcohol film used as a polarizer is usually a long film in the extending direction. On the other hand, since the polyester film used as the protective film is longitudinally stretched in the longitudinal direction and then laterally stretched, the polyester film is oriented in the transverse direction. That is, the main axis of alignment of the polyester film used as a polarizer protective film intersects approximately perpendicular to the longitudinal direction of the film. From the viewpoint of production efficiency, these films are usually bonded so that their longitudinal directions are parallel to each other to produce a polarizing plate. In this case, the fast axis of the polyester film and the transmission axis of the polarizer are usually perpendicular to each other. At this time, by using an aligned polyester film with a specific retardation as the polyester film, and using a continuous light source such as a white LED with a broad light emission spectrum as the backlight Source, iridescent spots will be greatly improved. However, when the backlight source includes a light emitting layer including a light source for emitting excitation light and quantum dots, it was found that there is still a new problem of rainbow spots.

Due to the increasing demand for color gamut expansion in recent years, in addition to the white light source using quantum dot technology, a white light source with a light emission spectrum in each wavelength region of R (red), G (green), and B (blue) has also been developed. A liquid crystal display device with a clear peak of relative luminous intensity. For example, to develop a liquid crystal display device corresponding to a wide color gamut, it uses the following various types of light sources: using excitation light with clear luminescence peaks in the R (red) and G (green) regions Phosphor-based white LED light source of light body and blue LED, white LED light source of 3-wavelength system, and white LED light source combined with red laser, etc. These white light sources have a narrower peak width at half maximum compared to conventional light sources including white light-emitting diodes using general-purpose YAG-based yellow phosphors. In these white light sources, when a polyester film having a retardation is used as a polarizer protective film that is a constituent member of a polarizer, it is found that there is a difference from the above-mentioned backlight light source having a light emitting layer including a light source that emits excitation light and quantum dots. The same problem as in the case of the liquid crystal display device.

That is, one of the subjects of the present invention is to provide a liquid crystal display device, as represented by a backlight light source including a light source emitting excitation light and a quantum dot, in which the liquid crystal having a backlight light source having a narrower half maximum width of each peak of the emission spectrum In display devices, when a polyester film is used as a polarizer protective film, rainbow spots can also be suppressed.

Representative inventions are as follows.

Item 1.

A liquid crystal display device, which is a liquid crystal display device with a backlight light source, a light source side polarizer, a liquid crystal cell, and a recognition side polarizer, wherein the backlight light source is between 400nm and less than 495nm, between 495nm and 600nm, and between 600nm and 780nm Each wavelength region has a peak top of the luminescent spectrum, and the half-maximum width of each peak is more than 5nm; the identification side polarizer includes a polyester film A with a retardation of 1500-30000nm, and at least one area layer of the polyester film A Anti-reflection layer and/or low-reflection layer; the polarizing plate on the light source side includes polyester film B; and when the retardation of polyester film B is determined as Re _B , the peak existing in the wavelength region of 600nm to 780nm of the backlight source Ry/[Rx/(Re _B /Rx)] is 0.55 or more when the wavelength of the peak top is Rx and the half-width is Ry.

Item 2.

The liquid crystal display device as described in Item 1, wherein the wavelength of the peak top existing in the wavelength range of 400 nm to 495 nm is defined as Bx, the half-maximum width is defined as By, and the wavelength of the peak present in the range of 495 nm to 600 nm is defined as Bx. Gx is the wavelength of the peak top of the peak in the wavelength region, and when the half-width is Gy, By/[Bx/(Re _B /Bx)] is 0.55 or more, and Gy/[Gx/(Re _B / Gx)] is 0.55 or more.

Item 3.

The liquid crystal display device according to Item 1 or 2, wherein the Rx is 630 nm or more.

Item 4.

The liquid crystal display device according to any one of items 1 to 3, wherein the Ry is 180 nm or less.

Item 5.

The liquid crystal display device according to any one of items 1 to 4, wherein the light source includes a light source for emitting excitation light and quantum dots.

Item 6.

The liquid crystal display device according to any one of items 1 to 5, wherein the surface reflectance of the surface of the antireflection layer at a wavelength of 550 nm is 2.0% or less.

The liquid crystal display device and the polarizing plate of the present invention have a wide color gamut, and in any viewing angle, can have good visibility that significantly suppresses the occurrence of iridescent color spots.

FIG. 1 shows an example of a case where a plurality of peaks exist in a single wavelength range.

FIG. 2 shows an example of a case where a plurality of peaks exist in a single wavelength region.

FIG. 3 shows an example of a case where a plurality of peaks exist in a single wavelength range.

FIG. 4 shows an example of a case where a plurality of peaks exist in a single wavelength range.

FIG. 5 is a graph showing the light transmittance of an alignment film having a retardation of 7000 nm.

Form of implementing the invention

Generally speaking, a liquid crystal display device has a rear module, a liquid crystal cell, and a front module in order from the side where the backlight source is configured (also called "backlight unit") to the side where the image is displayed (recognition side). The rear module and the front module are generally composed of a transparent substrate, a transparent conductive film formed on the side surface of the liquid crystal cell, and a polarizer arranged on the opposite side. That is, the polarizing plate is arranged on the side opposite to the backlight light source in the rear module, and is arranged on the display image side (recognition side) in the front module.

A liquid crystal display device has at least a backlight light source and a liquid crystal cell disposed between two polarizing plates as constituent members. The backlight light source preferably has a luminescent spectrum with a peak peak in each wavelength range of 400nm to 495nm, 495nm to 600nm, and 600nm to 780nm, and the half-maximum width of each peak is 5nm or more. The peak wavelengths of blue, green, and red defined by the CIE chromaticity diagram are known to be 435.8 nm (blue), 546.1 nm (green), and 700 nm (red), respectively. The aforementioned wavelength regions of 400nm to 495nm, 495nm to 600nm, and 600nm to 780nm correspond to the blue region, the green region, and the red region, respectively. As a light source having such an emission spectrum as described above, a backlight light source including at least a light source emitting excitation light and quantum dots can be mentioned. In addition, phosphor-type white LED light sources and three-wavelength-type white LEDs that use a combination of phosphors and LEDs that use excitation light having luminescence peaks in the R (red) and G (green) regions respectively can be exemplified. Light source, white LED light source combined with red laser, etc. Examples of the red phosphor among the aforementioned phosphors include, for example, a nitride-based phosphor whose basic composition is CaAlSiN ₃ :Eu, etc., a sulfide-based phosphor whose basic composition is CaS:Eu, etc., Ca ₂ SiO ₄ : a silicate-based phosphor with Eu or the like as the basic composition. In addition, as the green phosphor among the aforementioned phosphors, for example, a silicon nitride-based phosphor having β-SiAlON:Eu as a basic composition, and (Ba,Sr) ₂ SiO ₄ :Eu as a basic composition, etc. Silicate-based phosphor with basic composition.

The liquid crystal display device may have other configurations such as color filters, lens films, diffusion sheets, antireflection films, etc. besides the backlight, polarizing plates, and liquid crystal cells as appropriate. Between the polarizing plate on the light source side and the backlight light source, a brightness enhancing film may also be arranged. Examples of the brightness enhancement film include reflective polarizers that transmit one linearly polarized light and reflect a linearly polarized light orthogonal to it. As a reflective polarizing plate, for example, a DBEF (registered trademark) (Dual Brightness Enhancement Film) series brightness enhancement film manufactured by Sumitomo 3M Co., Ltd. can be suitably used. In addition, the reflective polarizing plate is usually arranged so that the absorption axis of the reflective polarizing plate is parallel to the absorption axis of the light source side polarizing plate.

Of the two polarizers arranged in the liquid crystal display device, the polarizer on the identification side preferably includes a polyester film A having a retardation of 1500 to 30000 nm, and at least one surface layer thereof Anti-reflection layer and/or low-reflection layer. The anti-reflection layer and/or the low-reflection layer may be provided on the side opposite to the surface of the laminated polarizer of the polyester film A, or may be provided on the surface of the laminated polarizer of the polyester film A, or may be for both sides. It is preferable to provide an antireflection layer and/or a low reflection layer on the surface of the laminated polyester film A opposite to the polarizer. When an antireflection layer and/or a low reflection layer is provided on the surface of the laminated polarizer of the polyester film A, it is preferable to provide this layer between the polyester film and the polarizer. Also, between the anti-reflection layer and/or the low-reflection layer and the polyester film A, there may be other layers (for example, an easy-adhesive layer, a hard coat layer, an antiglare layer, an antistatic layer, an antifouling layer, etc.) . From the viewpoint of further suppressing iridescent stains, the refractive index of the polyester film A in a direction parallel to the transmission axis of the polarizer is preferably 1.53 or more and 1.62 or less. It is preferable to laminate a non-birefringent film such as TAC film, acrylic film, and norbornene-based film on the other side of the polarizer (a three-layer polarizer), but it does not necessarily need to be on the other side of the polarizer Laminated film (two-layer polarizing plate). Furthermore, when the polyester film A is used as the protective film on both sides of the polarizer, it is preferable that the slow axes of the two polyester films are slightly parallel to each other.

The polyester film A can be laminated on the polarizer through any adhesive agent, or directly laminated without the adhesive agent. The adhesive is not particularly limited, and any one can be used. As an example, a water-based adhesive (that is, an adhesive component dissolved in water or dispersed in water) can be used. For example, an adhesive containing a polyvinyl alcohol-based resin and/or a urethane resin can be used as a main component. In order to improve adhesiveness, you may use the adhesive which further blended an isocyanate type compound, and/or an epoxy compound, etc. as needed. Moreover, as another example, a photocurable adhesive agent can also be used. In one embodiment, it is preferably a solvent-free ultraviolet curable adhesive. As a photocurable resin, the mixture etc. of a photocurable epoxy resin and a photocationic polymerization initiator are mentioned, for example.

The configuration of the backlight may be an edge lighting method using a light guide plate, a reflector, or the like as a constituent member, or may be a direct lighting method. The backlight light source is preferably a backlight light source including a light source that emits excitation light and a quantum dot as a representative example. And the backlight light source of the emission spectrum whose half-maximum width of each peak is 5nm or more". Furthermore, quantum dots can be provided in a layer containing a large number of quantum dots, and used as a light-emitting layer for backlighting, for example.

The application of quantum dot technology to LCD has become a technology that has attracted attention due to the high demand for color gamut expansion in recent years. LEDs that use ordinary white LEDs as backlight sources can only reproduce about 20% of the color spectrum that can be recognized by human eyes. On the other hand, it is said that when using a backlight light source including a light source that emits excitation light and a light-emitting layer including quantum dots, it is said that more than 60% of the colors of the spectrum recognizable by human eyes can be reproduced. Practical quantum dot technologies include QDEF ^TM from Nanosys or Color IQ ^TM from QD Vision.

The light-emitting layer including quantum dots is formed by including quantum dots in, for example, a resin material such as polystyrene, and is a layer that emits light of various colors in pixel units based on excitation light emitted from a light source. The light-emitting layer includes, for example, a red light-emitting layer disposed on a red pixel, a green light-emitting layer disposed on a green pixel, and a blue light-emitting layer disposed on a blue pixel. Quantum dots in these multicolor light-emitting layers are based on The excitation light generates luminescence lights of different wavelengths (colors).

As the material of the aforementioned quantum dots, for example, CdSe, CdS, ZnS: Mn, InN, InP, CuCl, CuBr, and Si, etc., the particle diameter (dimension in one side direction) of these quantum dots, for example It is about 2~20nm. In addition, among the aforementioned quantum dot materials, InP is exemplified as a red luminescent material, CdSc is exemplified as a green luminescent material, and CdS is exemplified as a blue luminescent material. As in the aforementioned light-emitting layer, by changing the size (particle size) of the quantum dots or the composition of the material, it can be confirmed that the light-emitting wavelength is changed. The size (particle size) or material of quantum dots is controlled, mixed with resin material, and each pixel is coated with different colors for use. In addition, since the use of heavy metals such as cadmium is limited in many applications, cadmium-free quantum dots are being developed while maintaining the same brightness and stability as conventional ones.

As a light source for emitting excitation light, a blue LED can be used, and laser light such as a semiconductor laser can also be used. When the excitation light emitted from the light source passes through the light-emitting layer, luminescence spectra having peaks in the respective wavelength regions of 400nm to 495nm, 495nm to 600nm, and 600nm to 780nm are generated. At this time, the narrower the half-value width of the peak in each wavelength region, the wider the color gamut, but if the half-value width of the peak is narrowed, the luminous efficiency will decrease. Therefore, the luminous spectrum is designed in consideration of the balance between the required color gamut and luminous efficiency. shape.

Light sources using quantum dots are not limited to the following, but generally there are two installation methods. One is along the end face (side) of the light guide plate of the backlight On-Edge way of installing quantum dots. The quantum dots with particle diameters of several nm to tens of nm are added to a glass tube with a diameter of several mm and sealed, and the foregoing is arranged between the blue LED and the light guide plate. Light from a blue LED shines through the glass tube, where the blue light hitting the quantum dots is converted to green or red light. The On-Edge method has the advantage of reducing the amount of quantum dots used even for large screens. The other is a surface-mounting method in which quantum dots are loaded on a light guide plate. The quantum dots are dispersed in the resin and flaked, the aforementioned is sandwiched by two barrier films, and the sealed quantum dot film is laid on the light guide plate. The barrier film plays a role of suppressing degradation of quantum dots by water or oxygen. The blue LED is placed on the end surface (side surface) of the light guide plate in the same way as the On-Edge method. The light from the blue LED enters the light guide plate as planar blue light, and it irradiates the quantum dot film. There are generally two advantages of the surface mount method. One is that the light of the blue LED hits the quantum dots through the light guide plate, so the influence of heat from the LED is small, and it is easy to ensure reliability. Another reason is that since it is in the form of a film, it is easy to respond to a wide range of screen sizes from small to large.

The backlight light source preferably has a peak top of the emission spectrum in each wavelength region of 400nm to 495nm, 495nm to 600nm, and 600nm to 780nm, and the half-width of each peak is 5nm or more. The wavelength range between 400nm and 495nm is more preferably 430nm to 470nm. The wavelength range of 495 nm to 600 nm is more preferably 510 nm to 560 nm. The wavelength region of 600nm to 780nm is more preferably 600nm to 750nm, further preferably 630nm to 700nm, and most preferably 630nm or more Below 680mn. The lower limit of the half width of each peak is preferably 10 nm or more, more preferably 15 nm or more, and further preferably 20 nm or more. From the viewpoint of ensuring the best color gamut, the upper limit of the half maximum width of each peak is preferably 180nm or less, preferably 140nm or less, preferably 120nm or less, preferably 100nm or less, more preferably 80nm or less, further More preferably, it is 60 nm or less, and still more preferably, it is 45 nm or less. In addition, the half-peak width here is the peak width (nm) of the intensity|strength of 1/2 of the peak intensity of the wavelength of a peak top. Each upper limit and lower limit of the wavelength region described here assumes any combination thereof. The respective upper limit and lower limit of the half width described here assume any combination of these. The peak intensity and the emission spectrum of the backlight light source can be measured, for example, using a multi-channel spectrometer PMA-12 manufactured by Hamamatsu Photonics K.K. or the like.

It is considered that there are multiple peaks in any one of the wavelength range of 400nm to 495nm, 495nm to 600nm, or 600nm to 780nm as follows. When a plurality of peaks are independent peaks, the half-width of the peak with the highest peak intensity is preferably within the above-mentioned range. In addition, about other peaks which have intensity|strength of 70% or more of the highest peak intensity, it is a more preferable aspect to make half-peak width into the said range similarly. Regarding one independent peak having a shape in which multiple peaks overlap, when the half-peak width of the peak with the highest peak intensity among the multiple peaks can be directly measured, the half-peak width is used. Here, an independent peak is one that has a region having an intensity of 1/2 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 with an intensity of 1/2 of the peak intensity, the plurality of peaks can be viewed as a whole for a peak. For one peak having a shape in which a plurality of peaks overlap, the width (nm) of the peak whose intensity is 1/2 of the highest peak intensity is defined as the half-peak width. Among the plurality of peaks, the point with the highest peak intensity was defined as the peak top. The half width at half peak when there are multiple peaks in a single wavelength region is indicated by double arrows in Figures 1 to 4.

In FIG. 1 , peaks A and B each start from the peak, and there are points on the short-wavelength side and the long-wavelength side that become 1/2 of the peak intensity. Therefore, peaks A and B are each independent peaks. In the case of FIG. 1 , it is only necessary to evaluate the half-peak width by the width of the double-headed arrow of peak A having the highest peak intensity.

In FIG. 2 , peak A has a point at 1/2 of the peak intensity on its short-wavelength side and long-wavelength side, but peak B does not have a point at 1/2 of its peak intensity on its long-wavelength side. Therefore, peak A and peak B are collectively regarded as one independent peak. Regarding one independent peak having a shape in which multiple peaks overlap, when the half-width of the peak with the highest peak intensity among the multiple peaks can be directly measured, the half-width is defined as the half-width of the independent peak. Therefore, in the case of Fig. 2, the width at half maximum of the peak is the width of the double-headed arrow.

In FIG. 3 , peak A does not have a point that becomes 1/2 of the peak intensity on the short wavelength side, and peak B does not have a point that becomes 1/2 of the peak intensity on the long wavelength side. Therefore, in FIG. 3 , peak A and peak B are collectively regarded as one independent peak similarly to the case of FIG. 2 , and the half-peak width thereof is the width indicated by the double-headed arrow.

In FIG. 4 , peak A has points at 1/2 of the peak intensity on its short wavelength side and long wavelength side, but peak B does not have a point at 1/2 of its peak intensity on its long wavelength side. Therefore, peak A and peak B are collectively regarded as one independent peak. Regarding one independent peak having a shape in which a plurality of peaks overlap, when the half-width of the peak with the highest peak intensity among the plurality of peaks can be directly measured, the half-width is used. Therefore, in the case of FIG. 4 , the width at half maximum is the width indicated by the double-headed arrow.

FIGS. 1 to 4 show examples of the wavelength range from 400 nm to 495 nm, but the same idea can also be applied to other wavelength ranges.

Among the plurality of peaks, the peak with the highest peak intensity was taken as the peak top. Furthermore, the peak with the highest peak intensity in the wavelength region of 400nm to 495nm, the wavelength region of 495nm to 600nm, or the wavelength region of 600nm to 780nm is preferably independent of peaks in other wavelength regions. . In particular, the wavelength region between the peak having the highest peak intensity in the wavelength region of 495nm to 600nm and the peak having the highest peak intensity in the wavelength region of 600nm to 780nm is preferable in terms of color clarity. There is a region where the intensity becomes 1/3 or less of the peak intensity of the peak having the highest peak intensity in the wavelength region of 600 nm to 780 nm.

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

The present invention has found that it is possible to provide a liquid crystal display device having a full width at half maximum of each peak of an emission spectrum such as a backlight light source including a light source emitting excitation light and a quantum dot, and a polarizing plate useful for providing the same. In a liquid crystal display device with a relatively narrow backlight source, as long as a polyester film with an anti-reflection layer and/or a low-reflection layer is used as a polarizer protective film and has a specific retardation, rainbow spots can be suppressed. It is considered that the mechanism for suppressing the generation of iridescent spots by the above-mentioned aspects is as follows.

When an alignment polyester film is arranged on one side of the polarizer, when the linearly polarized light emitted from the backlight unit or the polarizer passes through the polyester film, the polarization state changes. One of the main reasons for the change of the polarization state may be the refractive index difference at the interface between the air layer and the aligned polyester film, or the refractive index difference at the interface between the polarizer and the aligned polyester film. When the linearly polarized light incident on the alignment polyester film passes through each interface, part of the light is reflected by the difference in refractive index between the interfaces. At this time, the emitted light, reflected light, and polarization state all change, and this becomes one of the main causes of iridescent stains. Therefore, by providing an anti-reflection layer or a low-reflection layer on the surface of the aligned polyester film to reduce surface reflection, reflection at the interface between the air layer and the aligned polyester film can be suppressed, and iridescent stains can be suppressed.

As above, by combining a backlight light source having a relatively narrow half-width of each peak of the emission spectrum represented by a light source including a light source emitting excitation light and a backlight light source including quantum dots, and a polarizing plate using a polyester film as a polarizer protective film, It can suppress iridescent spots and has good recognition.

The polyester film A preferably has a retardation of not less than 1500 and not more than 30000 nm. If the delay is within the above range, it tends to be easier to reduce rainbow spots, which is preferable. A preferable lower limit of retardation is 3000 nm, a more preferable lower limit is 3500 nm, a more preferable lower limit is 4000 nm, an especially preferable lower limit is 6000 nm, and the most preferable lower limit is 8000 nm. A preferable upper limit is 30,000 nm, and a polyester film having a retardation above this tends to have a considerably large thickness, which tends to degrade its performance as an industrial material. In this specification, delay means in-plane delay unless otherwise indicated. In this specification, in order to distinguish it from the retardation of the polyester film B, the retardation of the polyester film A may be expressed as Re _A .

From the viewpoint of suppressing iridescent stains, it is preferable that the polarizing plate on the light source side includes polyester film B, and when its retardation is defined as Re _B , the peak that exists in the wavelength region of 600nm to 780nm of the backlight light source When the wavelength is Rx and the half-value width is Ry, Ry/[Rx/(Re _B /Rx)] is 0.55 or more. When Ry/[Rx/(Re _B /Rx)] is 0.55 or more, the occurrence of rainbow spots can be suppressed when the liquid crystal display device is observed from the front direction and obliquely, which is preferable. Ry/[Rx/(Re _B /Rx)] is more preferably at least 0.6, more preferably at least 0.65, still more preferably at least 0.7, particularly preferably at least 0.75, most preferably at least 0.8. The higher the value, the better, but from the viewpoint of thinning the alignment film and widening the color gamut of the liquid crystal display device, it is preferably 10 or less, more preferably 7 or less, still more preferably 5 or less, most preferably 3 or less . Furthermore, here, the retardation of the alignment film has a value of a wavelength of 589 nm.

When a birefringent body is arranged at the diagonal position between the crossed Nicols and a white light source is used as the backlight source, if the light transmitted through the crossed Nicols is defined as the interference color, the light transmittance is expressed by formula (1).

I/I ₀ =1/2‧sin ² (π‧Re/λ)…(1)

Here, I ₀ represents the intensity of light incident on the crossed Nicolian, I represents the intensity of light transmitted through the crossed Nicolian, and Re represents the retardation of the birefringent. As mentioned above, the transmittance (I/I ₀ ) varies with retardation and the wavelength of light, so a characteristic interference color is observed at the value of retardation. The light transmittance is a function represented by the square of sin as in the above formula (1), and as shown in FIG. 5 , it becomes a graph in which the transmittance intensity repeats up and down. Here, Rx/(Re _B /Rx) corresponds to the repetition interval (nm) of the transmission intensity at the wavelength Rx. Therefore, Ry/[Rx/(Re _B /Rx)] is an index showing that there are several repetitions of transmission intensity between the half widths Ry. The more the transmission intensity repeats between the half-value widths Ry, the more the rainbow spots observed on the display screen can be suppressed.

Rx is preferably not less than 600 nm and not more than 780 nm. Rx is preferably at least 630 nm, more preferably at least 635 nm, further preferably at least 640 nm, particularly preferably at least 645 nm. Also, the upper limit is preferably 780 nm or less, more preferably 700 nm or less, further preferably 680 nm or less. When Rx is 630nm or more, red can be displayed more vividly, and a wide color gamut can be secured. If it is 780 nm or less, it is preferable that a large amount of light in an easily identifiable area can be output.

Half width Ry is preferably 180nm or less, preferably 150nm or less, preferably 140nm or less, preferably 120nm or less, preferably 110nm or less below, preferably below 100 nm, more preferably below 80 nm, further preferably below 60 nm, particularly preferably below 45 nm. If the half maximum width is large, the light components in the orange gamut will increase, making it difficult to display pure red. Therefore, the value of Ry is preferably 180 nm or less. The lower limit of Ry is preferably at least 5 nm, more preferably at least 10 nm, further preferably at least 15 nm, and most preferably at least 20 nm.

Furthermore, when the wavelength of the peak top that exists in the wavelength region of 400nm to less than 495nm of the backlight light source is defined as Bx, and the half-maximum width is defined as By, the peak that exists in the wavelength region of 495nm to less than 600nm is defined as Bx. When the wavelength of the peak is Gx and the half-width is Gy, it is preferable that By/[Bx/(Re _B /Bx)] is 0.55 or more, and/or Gy/[Gx/(Re _B /Gx) ] is 0.55 or more. More preferably, By/[Bx/(Re _B /Bx)] is 0.55 or more, and Gy/[Gx/(Re _B /Gx)] is 0.55 or more. Both By/[Bx/(Re _B /Bx)] and Gy/[Gx/(Re _B /Gx)] are more preferably at least 0.60, more preferably at least 0.65, most preferably at least 0.7, and most preferably at least 0.75 above, preferably above 0.8. If it is 0.55 or more, the occurrence of rainbow spots can be further suppressed, which is preferable. The higher the equivalent value, the better, but from the viewpoint of thinning the alignment film and widening the color gamut of the liquid crystal display device, it is preferably 10 or less, more preferably 7 or less, further preferably 5 or less, and most preferably 3 the following.

Like Ry/[Rx/(Re _B /Rx)] above, Bx/(Re _B /Bx) is equivalent to the repetition interval (nm) of the transmission intensity at wavelength Bx, By/[Bx/(Re _B /Bx)] is an index showing that there are several repetitions of transmission intensity between the half widths By. Also, Gx/(Re _B /Gx) is equivalent to the repetition interval (nm) of the transmission intensity at the wavelength Gx, and Gy/[Gx/(Re _B /Gx)] means that there exists between the half-width Gy An indicator of the repetition of several transmitted intensities. The more repetitions of the respective transmission intensities of the half-value widths By and Gy, the more the rainbow spots observed on the display screen can be further suppressed.

Bx is preferably not less than 400 nm and less than 495 nm, and Gx is preferably not less than 495 nm and less than 600 nm. The upper limit of the half width By is preferably at most 100 nm, more preferably at most 70 nm, further preferably at most 60 nm, particularly preferably at most 50 nm. The lower limit of the half width By is preferably at least 5 nm, more preferably at least 8 nm, further preferably at least 10 nm, particularly preferably at least 12 nm. If it is less than 5 nm, iridescent unevenness is likely to occur.

The upper limit of the half width Gy is preferably 150 nm or less, more preferably 140 nm or less, preferably 120 nm or less, preferably 100 nm or less, more preferably 80 nm or less, further preferably 70 nm or less, particularly preferably 60 nm or less. The lower limit of the half width Gy is preferably at least 5 nm, more preferably at least 10 nm, further preferably at least 15 nm, and particularly preferably at least 20 nm. If it is less than 5 nm, iridescent unevenness is likely to occur.

In one embodiment, Bx is preferably not less than 430 nm and not more than 470 nm. Gx is preferably not less than 510 nm and not more than 560 nm.

As shown in Fig. 5, the relationship between transmittance and wavelength repeats up and down. As shown in FIG. 5 , the repetition interval tends to be longer in the long-wavelength region than in the short-wavelength region. Therefore, from the viewpoint of ensuring a wide color gamut, a liquid crystal display device having a white light source having a light emission spectrum with a narrow half width By, Gy, and Ry of each peak particularly satisfies Ry/[Rx/(Re _B /Rx)] The requirement of 0.55 or more is better than By/[Bx/(Re _B /Bx)] or Gy/[Gx/(Re _B /Gx)] to meet the conditions.

The polyester film B preferably has a retardation (Re _B ) of 3000-30000 nm. When the retardation is less than 3000 nm and is used as a polarizer protective film, interference colors may appear when observed from an oblique direction, and favorable visibility may not be ensured. A preferable lower limit of retardation is 4500 nm, a more preferable lower limit is 5000 nm, a more preferable lower limit is 6000 nm, a more preferable lower limit is 8000 nm, and a more preferable lower limit is 10000 nm.

On the other hand, even if an alignment film having a retardation exceeding 30,000 nm is used, not only the further effect of improving the visibility cannot be obtained substantially, but also the thickness of the film becomes considerably thicker, which is not preferable as an industrial material because of poor handling.

The retardation of the polyester film can be obtained by measuring the refractive index and thickness in the biaxial direction, or can be obtained by using a commercially available automatic birefringence measuring device such as KOBRA-21ADH (Oji Scientific Instruments Co., Ltd.). In addition, the refractive index can be calculated|required with the Abbe refractometer (measurement wavelength 589nm).

The ratio (Re/Rth) of the retardation (Re: in-plane retardation) of the polyester films A and B to the retardation in the thickness direction (Rth) is preferably 0.2 or more, preferably 0.3 or more, preferably 0.4 or more, preferably 0.5 or more, more preferably 0.5 or more, further preferably 0.6 or more. The larger the ratio (Re/Rth) of the retardation to the retardation in the thickness direction, the more isotropic the effect of birefringence, and it tends to become difficult to generate iridescent color irregularities due to viewing angles. From the point of view that the ratio (Re/Rth) of the retardation to the retardation in the thickness direction becomes 2.0 in a completely uniaxial (uniaxially symmetric) film, the upper limit of the ratio (Re/Rth) of the retardation to the retardation in the thickness direction is preferably is 2.0. A preferable upper limit of Re/Rth is 1.2 or less. In addition, the retardation in the thickness direction means the average retardation obtained by multiplying the two birefringences ΔNxz and ΔNyz when the film is viewed in the thickness direction by the thickness d of the film.

From the viewpoint of further suppressing rainbow spots, the NZ coefficients of the polyester films A and B are preferably at most 2.5, more preferably at most 2.0, further preferably at most 1.8, and still more preferably at most 1.6. In addition, since the NZ coefficient becomes 1.0 in a completely uniaxial (monoaxially symmetric) thin film, the lower limit of the NZ coefficient is 1.0. However, it is necessary to pay attention to the fact that the mechanical strength in the direction perpendicular to the alignment direction tends to decrease significantly as the thin film approaches a complete uniaxiality (uniaxial symmetry).

The NZ coefficient is represented by |Ny-Nz|/|Ny-Nx|, where Ny represents the refractive index in the direction of the slow axis, Nx represents the refractive index in the direction perpendicular to the slow axis (refractive index in the direction of the fast axis), and Nz Indicates the refractive index in the thickness direction. Using a molecular alignment meter (Molecular Orientation Meter MOA-6004, manufactured by Oji Scientific Instruments Co., Ltd.), the alignment axis of the thin film was obtained, and the biaxial refractive index (Ny, Nx) in the direction of the alignment axis and the direction perpendicular to it was obtained. , However, Ny>Nx) and the refractive index (Nz) in the thickness direction were determined with an Abbe refractometer (manufactured by ATAGO, NAR-4T, measurement wavelength: 589 nm). The NZ coefficient can be obtained by substituting the numerical value obtained in this way into |Ny-Nz|/|Ny-Nx|.

Also, from the viewpoint of further suppressing iridescent stains, the Ny-Nx values of the polyester films A and B are preferably at least 0.05, more preferably at least 0.07, still more preferably at least 0.08, and still more preferably at least 0.09. , the optimal value is above 0.1. The upper limit is not particularly limited, but in the case of a polyethylene terephthalate film, the upper limit is preferably about 1.5.

In each polarizer on the recognition side and the light source side, the direction of the absorption axis of the polarizer and the direction of the slow axis of the polyester film (A, B) are preferably slightly parallel or slightly perpendicular. From the viewpoint of production efficiency, the direction of the absorption axis of the polarizer is preferably slightly perpendicular to the direction of the slow axis of the polyester film (A, B). Here, slightly parallel means that the angle formed by the absorption axis and the slow axis is preferably ±15° or less, more preferably ±10° or less, still more preferably ±5° or less, further preferably ±3° or less, More preferably, it is ±2° or less, and most preferably, it is ±1° or less. In a preferred embodiment, slightly parallel is substantially parallel. Here, substantially parallel means that the absorption axis and the slow axis are parallel to the extent that unavoidable deviations are allowed. Here, slightly perpendicular means that the angle formed by the absorption axis and the slow axis is preferably ±15° or less, more preferably ±10° or less, still more preferably ±5° or less, further preferably ±3° or less, More preferably, it is ±2° or less, and most preferably, it is ±1° or less. In a preferred embodiment, slightly vertical is substantially vertical. Here, substantially perpendicular means that, to the extent that unavoidable deviations are allowed, the The receiving axis is perpendicular to the slow axis. The direction of the slow axis can be obtained by measuring with a molecular alignment meter (for example, MOA-6004 molecular alignment meter manufactured by Oji Scientific Instruments Co., Ltd.).

In the liquid crystal display devices of IPS mode and VA mode, the polarizing plate on the identification side is usually arranged so that the direction of the absorption axis of the polarizing plate on the identification side is parallel to the horizontal direction of the screen, and the polarizing plate on the light source side is arranged so that the polarizing plate on the light source side The direction of the absorption axis is arranged so as to be parallel to the vertical direction of the screen.

In one suitable embodiment, the refractive index of the polyester film A in a direction parallel to the transmission axis direction of the polarizer constituting the identification side polarizer is preferably in the range of 1.53 to 1.62. Thereby, reflection at the interface between the polarizer and the polyester film A can be suppressed, and iridescent stains can be effectively suppressed. If the refractive index exceeds 1.62, iridescent spots will appear when viewed obliquely. The refractive index of the polyester film A in a direction parallel to the transmission axis direction of the polarizer is preferably 1.61 or less, more preferably 1.60 or less, further preferably 1.59 or less, still more preferably 1.58 or less. The same relationship as this is also applicable to the refractive index of the polyester film B in the direction parallel to the transmission axis direction of the polarizer of the light source side polarizing plate.

On the other hand, the lower limit of the refractive index of the polyester film A in the direction parallel to the transmission axis direction of the polarizer of the identification side polarizer is 1.53. If the refractive index is less than 1.53, the crystallization of the polyester film becomes insufficient, and the dimensional stability, mechanical strength, chemical resistance, etc. are obtained by stretching. Features become insufficient and therefore less favorable. The refractive index is preferably at least 1.56, more preferably at least 1.57. Arbitrary ranges in which each upper limit and each lower limit of the above-mentioned refractive index are combined are assumed. The same relationship as this is also applicable to the refractive index of the polyester film B in the direction parallel to the transmission axis direction of the polarizer of the light source side polarizing plate.

It is desired to set the refractive index of the polyester film in a direction parallel to the transmission axis direction of the polarizer to a range of not less than 1.53 and not more than 1.62, preferably between the transmission axis of the polarizer and the fast axis of the polyester film laminated on the polarizer ( perpendicular to the slow axis) and parallel to it. By stretching the polyester film in the film forming step described later, the refractive index in the direction of the fast axis perpendicular to the slow axis can be adjusted down to about 1.53 to 1.62. By making the fast axis direction of the polyester film parallel to the transmission axis direction of the polarizer, the refractive index of the polyester film in the direction parallel to the transmission axis direction of the polarizer can be set to 1.53-1.62. Here, parallel means that the angle formed by the transmission axis of the polarizer and the fast axis of the polarizer protective film is -15°~15°, preferably -10°~10°, more preferably -5°~5° , more preferably -3°~3°, further preferably -2°~2°, particularly preferably -1°~1°. In a preferred embodiment, parallel is substantially parallel. Here, being substantially parallel means that the transmission axis is parallel to the fast axis to the extent that tolerances inevitably occur when bonding the polarizer and the protective film are allowed. The direction of the slow axis can be obtained by measuring with a molecular alignment meter (for example, MOA-6004 molecular alignment meter manufactured by Oji Scientific Instruments Co., Ltd.).

That is, the refractive index in the direction of the fast axis of the polyester films A and B is preferably 1.53 to 1.62, so that the transmission axis of the polarizer is aligned with the polyester film. Films A and B are laminated so that their fast axes are approximately parallel, and the refractive index of polyester films A and B in a direction parallel to the transmission axis of the polarizer can be 1.53 to 1.62.

In the polarizing plate on the identification side, the polarizer protective film including the polyester film A can be arranged on the light source side, on the identification side, or on both sides with the polarizer as a starting point, but preferably at least on the recognition side. In the polarizing plate on the light source side, the polarizer protective film including the polyester film B can be arranged on the light source side, the identification side, or both sides with the polarizer as a starting point, but preferably at least on the light source side.

The polarizing plate on the identification side can have other polarizing plate protective films on the non-laminated polyester film A side of the polarizing plate. In addition, the polarizing plate on the light source side may have another polarizing plate protective film on the non-laminated polyester film B side of the polarizing plate. The types of other protective films are optional, and can be appropriately selected, and those conventionally used as protective films are used. From the viewpoint of ease of handling and acquisition, for example, it is preferable to use a film selected from the group consisting of triacetylcellulose (TAC) film, acrylic film, and cyclic olefin-based resin film (norbornene-based film), polyester One or more kinds of non-birefringent films from the group of acrylic film and polyolefin-based resin film (for example, TPX) are used as other polarizer protective films.

In one embodiment, the protective film on the light source side of the polarizer on the identification side and the protective film on the identification side of the polarizer on the light source side preferably have optical compensation. Optical compensation film with compensation function. Such an optical compensation film can be appropriately selected in accordance with various forms of liquid crystals. disperse resins, cyclic olefin resins (e.g., norcamphene resins), acryl acetate resins, polycarbonate film resins, acrylic resins, styrene-acrylonitrile copolymer resins, lactone ring-containing resins , and one or more of the group containing imide group-containing polyolefin resin and the like.

Since an optical compensation film is commercially available, it can also select and use it suitably. Examples include "Wide View-EA" and "Wide View-T" (manufactured by Fuji Film Corporation) for the TN system, "Wide View-B" (manufactured by Fuji Film Corporation) for the VA system, and VA-TAC ( KONICA MINOLTA Corporation), "ZEONOR Film" (Japan Zeon Corporation), "ARTON" (JSR Corporation), "X-plate" (Nitto Denko Corporation), and "Z-TAC" (Fuji Film Co., Ltd.), "CIG" (Nitto Denko Co., Ltd.), "P-TAC" (Okura Kogyo Co., Ltd.), etc.

The polyester used in the polyester film may be polyethylene terephthalate or polyethylene naphthalate, and may contain other copolymerization components. These resins have good transparency and excellent thermal and mechanical properties, and retardation can be easily controlled by stretching. In particular, from the viewpoint that the inherent birefringence is large, the refractive index in the direction of the fast axis (perpendicular to the slow axis direction) can be suppressed to be low by stretching the film, and a large retardation is relatively easy to be obtained even if the film is thin, Polyon Ethylene phthalate is the most suitable material.

For the purpose of suppressing deterioration of optically functional pigments such as iodine pigments, the polyester film preferably has a light transmittance of 20% or less at a wavelength of 380 nm. The light transmittance at 380 nm is more preferably at most 15%, further preferably at most 10%, and most preferably at most 5%. If the light transmittance is 20% or less, it is possible to suppress deterioration of the optical functional dye due to ultraviolet rays. In addition, the transmittance is measured perpendicular to the plane of the film, and can be measured using a spectrophotometer (for example, Hitachi U-3500).

In order to make the transmittance of the polyester film at a wavelength of 380 nm 20% or less, it is preferable to appropriately adjust the type and concentration of the ultraviolet absorber and the thickness of the film. The ultraviolet absorber used in this invention is a well-known thing. Examples of the ultraviolet absorber include organic ultraviolet absorbers and inorganic ultraviolet absorbers, but organic ultraviolet absorbers are preferred from the viewpoint of transparency. Examples of organic ultraviolet absorbers include benzotriazole-based, benzophenone-based, cyclic imide-based, and combinations thereof, but there is no particular limitation as long as the absorbance is within the range defined by the present invention. However, from the viewpoint of durability, benzotriazole-based and cyclic imide-based are particularly preferable. When two or more kinds of ultraviolet absorbers are used together, ultraviolet rays of different wavelengths can be absorbed at the same time, so the ultraviolet absorption effect can be further improved.

-4-酮)、2-甲基-3,1-苯并

-4-酮、2-丁基-3,1-苯并

-4-酮、2-苯基-3,1-苯并

-4-酮等。但是並沒有特別限定於該等。 Examples of benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and acrylonitrile-based ultraviolet absorbers include 2-[2'-hydroxy-5'-(methacryloxymethyl )phenyl]-2H-benzotriazole, 2-[2'-hydroxyl-5'-(methacryloxyethyl)phenyl]-2H-benzotriazole, 2-[2'-hydroxyl -5'-(methacryloxypropyl)phenyl]-2H-benzotriazole, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,4-di-tertiary butyl-6-(5-chlorobenzotriazol-2-yl)phenol, 2-(2'-hydroxy-3 '-Tertiary butyl-5'-tolyl)-5-chlorobenzotriazole, 2-(5-chloro(2H)-benzotriazol-2-yl)-4-methyl-6-( Tertiary butyl)phenol, 2,2'-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol etc. Examples of cyclic imide ester-based ultraviolet absorbers include (2,2'-(1,4-phenylene)bis(4H-3,1-benzo

-4-keto), 2-methyl-3,1-benzo

-4-keto, 2-butyl-3,1-benzo

-4-one, 2-phenyl-3,1-benzo

-4-one etc. However, it is not particularly limited to these.

Moreover, in addition to the ultraviolet absorber, it is also a preferable aspect to contain various additives other than the catalyst within the range that does not hinder the effect of the present invention. Examples of additives include inorganic particles, heat-resistant polymer particles, alkali metal compounds, alkaline earth metal compounds, phosphorus compounds, antistatic agents, light stabilizers, flame retardants, heat stabilizers, antioxidants, and antigelling agents. , Surfactants, etc. Moreover, in order to realize high transparency, it is also preferable not to contain particle|grains substantially in a polyester film. "Substantially not containing particles" means, for example, in the case of inorganic particles, the content is 50 ppm or less, preferably 10 ppm or less, particularly preferably below the detection limit, when quantitative inorganic elements are analyzed by phosphorescent X-ray analysis.

Preferably, an anti-reflection layer and/or a low-reflection layer are provided on at least one surface of the polyester film A serving as the polarizer protective film of the polarizer on the identification side. The surface reflectance of the antireflection layer is preferably 2.0% or less. If it exceeds 2.0%, iridescent stains will be easily recognized. The surface reflectance of the antireflection layer is more preferably at most 1.6%, further preferably at most 1.2%, and most preferably at most 1.0%. The lower limit of the surface reflectance of the antireflection layer is not particularly limited, but is, for example, 0.01%. The reflectance can be measured by any method. For example, the reflectance of light having a wavelength of 550 nm can be measured from the surface on the antireflection layer side using a spectrophotometer (manufactured by Shimadzu Corporation, UV-3150).

The anti-reflection layer can be a single layer or a multilayer. In the case of a single layer, if the thickness of the low-refractive-index layer containing a material with a lower refractive index than the polyester film is made to be 1/4 of the wavelength of light or its odd Formed in several times, the anti-reflection effect can be obtained. Also, when the antireflection layer is multilayered, an antireflection effect can be obtained by laminating two or more low-refractive-index layers and high-refractive-index layers alternately and appropriately controlling the thickness of each layer. Also, if necessary, a hard coat layer may be laminated between the antireflection layers, and an antifouling layer may be formed on the hard coat layer.

As an antireflection layer, what utilizes a moth-eye structure is mentioned. The moth-eye structure is a concavo-convex structure with a pitch smaller than the wavelength formed on the surface, and this structure can change a sudden and discontinuous change in refractive index at the boundary with air into a continuous and gradual change in refractive index. Therefore, by forming the moth-eye structure on the surface, light reflection on the surface of the film can be reduced. Formation of the antireflection layer using the moth-eye structure can be carried out with reference to, for example, JP 2001-517319 A.

As a method for forming an antireflection layer, for example, a dry coating method in which an antireflection layer is formed on the surface of a substrate (polyester film) by vapor deposition or sputtering; Drying to form a wet coating method of an anti-reflection layer; or a combination method using both of them. The composition of the antireflection layer and its forming method are not particularly limited as long as the above characteristics are satisfied.

A well-known one can be used for a low reflection layer. For example, a thin film of a metal or an oxide is formed by laminating at least one layer by vapor deposition or sputtering; or by applying one or more layers of an organic thin film. As the low reflection layer, one coated with an organic thin film having a lower refractive index than a polyester film or a hard coat layer laminated on a polyester film can be suitably used. The surface reflectance of the low reflection layer is preferably less than 5%, more preferably 4% or less, further preferably 3% or less. The lower limit is preferably about 0.8% to 1.0%.

An anti-glare function may be further imparted to the anti-reflection layer and/or the low-reflection layer. Thereby, rainbow spots can be further suppressed. That is, a combination of an antireflection layer and an antiglare layer, a combination of a low reflection layer and an antiglare layer, or a combination of an antireflection layer, a low reflection layer, and an antiglare layer may also be used. Especially preferred is the combination of low reflection layer and anti-glare layer. As the antiglare layer, known antiglare layers can be used. For example, from the viewpoint of suppressing surface reflection of the film, it is preferable to laminate an antireflection layer or a low reflection layer on the antiglare layer after laminating an antiglare layer on the polyester film A.

When providing an antireflection layer or a low reflection layer, it is preferable that the polyester film A has an easy-adhesive layer on the surface. At this time, from suppressing reflected light due to From the viewpoint of interference, it is preferable to adjust the refractive index of the easily-adhesive layer to be in the vicinity of the average multiplied refractive index of the antireflection layer and the refractive index of the polyester film. The adjustment of the refractive index of the easily-adhesive layer can adopt a known method, for example, by making the binder resin contain titanium, germanium, or other metal species, it can be easily adjusted.

In order to improve the adhesion with the polarizer, the polyester film may be subjected to corona treatment, coating treatment and/or flame treatment.

In the present invention, in order to improve the adhesiveness with the polarizer, it is preferable that at least one side of the film of the present invention has at least one kind of polyester resin, polyurethane resin or polyacrylic resin as the main material. Easy-to-adhesive layer of ingredients. Here, the "main component" refers to a component of 50% by mass or more in the solid content constituting the easily-adhesive layer. The coating liquid used for forming the easy-adhesive 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 such coating liquids include those disclosed in Japanese Patent No. 3567927, Japanese Patent No. 3589232, Japanese Patent No. 3589233, Japanese Patent No. 3900191, and Japanese Patent No. 4150982. Water-soluble or water-dispersible copolymerized polyester resin solution, acrylic resin solution, or polyurethane resin solution, etc.

The easy-adhesive layer can be obtained by coating the aforementioned coating liquid on one or both sides of a uniaxially stretched film in the longitudinal direction, drying at 100-150°C, and stretching in the transverse direction. The coating amount of the final easy-adhesive layer is preferably controlled to be 0.05~0.20g/m ² . When the coating amount is less than 0.05 g/m ² , the adhesiveness with the obtained polarizer may become insufficient. On the other hand, when the coating amount exceeds 0.20 g/m ² , blocking resistance may decrease. When the easy-adhesive layer is provided on both surfaces of the polyester film, the application amount of the easily-adhesive layer on both surfaces may be the same or different, and may be set within the above-mentioned range independently.

The easy-adhesive layer preferably adds particles in order to provide slipperiness. It is preferable to use particles having an average particle diameter of 2 μm or less. When the average particle diameter of the particles exceeds 2 μm, the particles tend to fall off from the coating layer. Examples of particles contained in the easy-adhesive layer include titanium oxide, barium sulfate, calcium carbonate, calcium sulfate, silicon dioxide, alumina, talc, kaolin, clay, calcium phosphate, mica, hectorite, zirconia, Inorganic particles such as tungsten oxide, lithium fluoride, and calcium fluoride, or organic polymer particles such as styrene, acrylic, melamine, benzoguanamine, and silicone. These may be added individually to an easy-adhesive layer, and may be added in combination of 2 or more types.

In addition, known methods can be used as a method of applying the coating liquid. For example, reverse roll coating method, gravure coating method, kiss coating method, roll brush method, spray coating method, air knife coating method, wire bar coating method, and tubular blade coating method etc. may be mentioned, and may be used alone or in combination. methods for doing so.

In addition, the measurement of the average particle diameter of the said particle|grains was performed by the following method. The particles were photographed with a scanning electron microscope (SEM) to The size of the smallest particle becomes a magnification of 2~5mm, and the maximum diameter (the distance between the farthest 2 points) of 300~500 particles is measured, and the average value is taken as the average particle diameter.

The polyester films A and B used as polarizer protective films can be manufactured according to a general method for producing polyester films. For example, the polyester resin is melted and extruded into a sheet, and the formed non-oriented polyester is stretched in the longitudinal direction at a temperature above the glass transition temperature by using a speed difference of the rollers, and then stretched by a tenter. A method of extending laterally and performing heat treatment.

The polyester film may be a uniaxially stretched film or a biaxially stretched film.

When the film-forming conditions of a polyester film are demonstrated concretely, it is preferable that it is 80-130 degreeC, and it is especially preferable that it is 90-120 degreeC for longitudinal stretching temperature and transverse stretching temperature. To align the film with the slow axis in the TD direction, the longitudinal elongation ratio is preferably 1.0-3.5 times, and particularly preferably 1.0-3.0 times. Also, the lateral stretch ratio is preferably 2.5 to 6.0 times, and particularly preferably 3.0 to 5.5 times. To align the film with the slow axis in the MD direction, the longitudinal stretch ratio is preferably 2.5 to 6.0 times, and particularly preferably 3.0 to 5.5 times. Also, the lateral stretch ratio is preferably 1.0 to 3.5 times, and particularly preferably 1.0 to 3.0 times.

On the premise of reducing the refractive index in the fast axis direction of the polyester film and increasing the retardation, it is also a better response to set the stretching temperature to be low. Next, in the heat treatment, the treatment temperature is preferably 100-250°C, particularly preferably 180-245°C.

In order to suppress fluctuations in 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 preferable to also optimize the film forming conditions from the viewpoint of reducing the thickness unevenness. In particular, if the longitudinal stretching magnification is reduced in order to increase the retardation, the longitudinal thickness unevenness becomes large. Since the thickness unevenness in the longitudinal direction has a very poor region in a specific range of stretching ratio, it is preferable to set the film forming conditions to avoid this range.

The thickness unevenness of the polyester films A and B is preferably at most 5.0%, more preferably at most 4.5%, further preferably at most 4.0%, and most preferably at most 3.0%. The thickness variation of the film can be measured as follows. A tape-like film sample (3 m) was collected, and the thickness was measured at 100 points at a pitch of 1 cm using an electronic micrometer manufactured by Seiko Em Co., Ltd., Millitron 1240. The maximum value (dmax), the minimum value (dmin), and the average value (d) of the thickness were obtained from the measured values, and thickness unevenness (%) was calculated by the following formula. The measurement is preferably performed three times to obtain the average value.

Uneven thickness (%)=((dmax-dmin)/d)×100

As mentioned above, in order to control the retardation of a polyester film in a specific range, it can carry out by setting stretching ratio, stretching temperature, and the thickness of a film suitably. For example, the higher the stretching ratio, the lower the stretching temperature, and the thicker the film, the easier it is to obtain retardation. Conversely, the lower the stretching ratio, the higher the stretching temperature, and the thinner the film thickness, the easier it is to obtain low retardation. However, when the thickness of the film is increased, the retardation in the thickness direction tends to increase. because Here, the film thickness is preferably set appropriately within the range described later. In addition, it is preferable to set the final film forming conditions in consideration of physical properties required for processing and the like in addition to retardation control.

The thicknesses of the polyester films A and B are arbitrary, but are preferably in the range of 15 to 300 μm, more preferably in the range of 15 to 200 μm. Even a thin film with a thickness of less than 15 μm can obtain a retardation of 1500 nm or more in principle. However, in this case, the anisotropy of the mechanical properties of the thin film becomes remarkable, and splitting, cracking, etc. tend to occur, and the practicability as an industrial material significantly decreases. The lower limit of the particularly preferable thickness is 25 μm. On the other hand, when the upper limit of the thickness of the polarizer protective film exceeds 300 μm, the thickness of the polarizer 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. The upper limit of the optimum thickness is 100 μm, which is equivalent to that of general TAC films. In order to control the retardation to the above-mentioned range also in the above-mentioned thickness range, polyethylene terephthalate is suitable as the polyester used as the film base material.

Also, known methods can be used in combination as a method of blending the ultraviolet absorber into the polyester film. For example, a kneading extruder can be used in advance to prepare a dry ultraviolet absorber mixed with a polymer raw material. The master batch is blended by a predetermined method of mixing the master batch and polymer raw materials during film formation.

At this time, the ultraviolet absorber concentration of the masterbatch is set at a concentration of 5 to 30% by mass in order to uniformly disperse the ultraviolet absorber and blend economically. better. As a condition for making master batches, it is preferable to use a kneading extruder to extrude at a temperature above the melting point of the polyester raw material and below 290°C for 1 to 15 minutes. Above 290°C, the weight loss of the ultraviolet absorber is large, and the viscosity of the masterbatch decreases greatly. When the extrusion time is less than 1 minute, uniform mixing of the ultraviolet absorber becomes difficult. At this time, if necessary, a stabilizer, a color adjustment agent, and/or an antistatic agent may be added.

Preferably, the polyester film has a multilayer structure of at least three layers, and an ultraviolet absorber is added to the middle layer of the film. A film having a three-layer structure including an ultraviolet absorber in an intermediate layer can be specifically produced as follows. The polyester pellets for the outer layer alone, the masterbatch containing the ultraviolet absorber for the intermediate layer, and the polyester pellets for the intermediate layer are mixed in a predetermined ratio and dried, and then supplied to a known extruder for fusion lamination. It is extruded from a slit-shaped die into a thin sheet, cooled and solidified on a casting roll to produce an unstretched film. That is, using two or more extruders, three-layer manifolds or confluence blocks (for example, confluence blocks with square-shaped confluence parts), the film layers constituting the two outer layers and the film layers constituting the middle layer are laminated, A 3-layer sheet is extruded at the head and cooled by a casting roll to produce an unstretched film. Furthermore, in the invention, in order to remove foreign matter contained in the raw material polyester that 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 material used in the high-precision filtration of molten resin is preferably 15 μm or less. When the filter particle size of the filter medium exceeds 15 μm, the removal of foreign matter of 20 μm or more tends to be insufficient.

[Example]

The present invention will be described in more detail below with reference to the examples, but the present invention is not limited to the examples, and can also be implemented by adding appropriate changes within the scope suitable for the gist of the present invention, and these are all included in the scope of the present invention range of technologies. In addition, the evaluation method of the physical property of the following Example is as follows.

(1) Refractive index of polyester film

Using a molecular alignment meter (Molecular Orientation Meter MOA-6004, manufactured by Oji Scientific Instruments Co., Ltd.), the slow axis direction of the film was obtained so that the slow axis direction was parallel to the long side, and a rectangle of 4 cm x 2 cm was cut out. , and used as a sample for measurement. For this sample, the refractive index of the two orthogonal axes (refractive index in the slow axis direction: Ny, fast axis (refractive index in the direction perpendicular to the slow axis direction): Nx), and the refractive index in the thickness direction (Nz ) was determined with an Abbe refractometer (manufactured by ATAGO, NAR-4T, measurement wavelength: 589 nm).

(2) Delay (Re)

Retardation is a parameter defined by the product (ΔNxy×d) of the refractive index anisotropy (△Nxy=|Nx-Ny|) of the orthogonal biaxial axes on the film and the film thickness d (nm), and is A standard indicating optical isotropy and anisotropy. The biaxial refractive index anisotropy (ΔNxy) was obtained by the method (1) above, and the absolute value (| Nx-Ny |) of the aforementioned biaxial refractive index difference was taken as the refractive index anisotropy ( ΔNxy) and calculated. Thickness d (nm) of the film uses a motorized micrometer (manufactured by Feinpruf, Millitron 1245D) The measurement is performed and the unit is converted to nm. The retardation (Re) was obtained from the product (ΔNxy×d) of the anisotropy of the refractive index (ΔNxy) and the thickness d (nm) of the film.

(3) Thickness retardation (Rth)

Retardation in the thickness direction is obtained by multiplying the two birefringence △Nxz(=|Nx-Nz|) and △Nyz(=|Ny-Nz|) by the film thickness d when viewed from the film thickness direction section Latency averaging parameter. Obtain Nx, Ny, Nz and film thickness d (nm) by the same method as the measurement of retardation, and calculate the average value of (△Nxz×d) and (△Nyz×d) to obtain thickness direction retardation (Rth) .

(4) NZ coefficient

Substitute the values of Ny, Nx, and Nz obtained by the above (1) into the formula (NZ=|Ny-Nz|/|Ny-Nx|) to obtain the value of the NZ coefficient.

(5) Determination of the luminescence spectrum of the backlight source

The emission spectrum of the backlight source of the liquid crystal display device was measured using a multi-channel spectrometer PMA-12 manufactured by Hamamatsu Photonics K.K. In addition, the exposure time at the time of spectrum measurement was set to 20 msec.

(6) Reflectivity

Using a spectrophotometer (manufactured by Shimadzu Corporation, UV-3150), the 5-degree reflectance at a wavelength of 550 nm was measured from the surface on the antireflection layer side (or low reflection layer side). Furthermore, after setting the anti-reflection layer of polyester film (or The low-reflection layer) side is the opposite side, and black vinyl tape (Kyowa (stock) vinyl tape HF-737 width 50mm) is attached to the surface after coating with a black marker for measurement.

(7) Observation of rainbow spots

The liquid crystal display devices obtained in each Example were visually observed from the front and obliquely in a dark place, and the presence or absence of rainbow spots was determined as follows. Here, the oblique direction means a range of 30 degrees to 60 degrees from the normal direction of the screen of the liquid crystal display device.

○: No rainbow spot was observed

Δ: Rainbow spots are slightly observed

×: Rainbow spot observed

(Manufacturing example 1-polyester A)

When the temperature of the esterification reaction tank was raised to 200°C, 86.4 parts by mass of terephthalic acid and 64.6 parts by mass of ethylene glycol were added, and while stirring, 0.017 parts by mass of antimony trioxide and acetic acid were added as catalysts. 0.064 parts by mass of magnesium tetrahydrate, and 0.16 parts by mass of triethylamine. Next, pressurization and temperature rise were performed, and after pressurization esterification reaction was performed on the conditions of gauge pressure 0.34MPa and 240 degreeC, the esterification reaction tank was returned to normal pressure, and phosphoric acid 0.014 mass part was added. Furthermore, it heated up to 260 degreeC over 15 minutes, and added 0.012 mass parts of trimethyl phosphates. Next, 15 minutes later, dispersion treatment was performed with a high-pressure disperser, and 15 minutes later, the obtained esterification reaction product was transferred to a polycondensation reaction tank, and polycondensation reaction was performed at 280° C. under reduced pressure.

After the polycondensation reaction is completed, filter through a Naslon filter with a 95% cut diameter of 5 μm, extrude into strands from a nozzle, and cool and solidify with cooling water that has previously been filtered (pore size: 1 μm or less). And cut into pellets. The obtained polyethylene terephthalate resin (A) had an intrinsic viscosity of 0.62 dl/g, and substantially did not contain inert particles and internal precipitated particles (hereinafter abbreviated as PET (A)).

(Manufacturing example 2-polyester B)

-4-酮)10質量份、未包含粒子之PET(A)(固有黏度為0.62dl/g)90質量份，使用混練擠製機，得到含有紫外線吸收劑之聚對苯二甲酸乙二酯樹脂(B)(以下省略為PET(B))。 Mixed dry UV absorber (2,2'-(1,4-phenylene)bis(4H-3,1-benzo

-4-ketone) 10 parts by mass, 90 parts by mass of PET (A) (intrinsic viscosity: 0.62dl/g) excluding particles, using a kneading extruder to obtain polyethylene terephthalate containing an ultraviolet absorber Resin (B) (hereinafter abbreviated as PET (B)).

(Manufacturing Example 3-Adjustment of Adhesive Modification Coating Solution)

Transesterification reaction and polycondensation reaction were carried out by conventional methods, and prepared as dicarboxylic acid components (relative to the whole dicarboxylic acid components) 46 mol% of terephthalic acid, 46 mol% of isophthalic acid and 5-sulfonic acid Water-dispersible sulfonic acid metal base composed of 8 mol% of sodium ester isophthalate, 50 mol% of ethylene glycol and 50 mol% of neopentyl glycol as glycol components (relative to the entire glycol component) copolymerized polyester resin. Next, after mixing 51.4 parts by mass of water, 38 parts by mass of isopropanol, 5 parts by mass of n-butyl cylusol, and 0.06 parts by mass of a nonionic surfactant, heat and stir, and once it reaches 77°C, add the above-mentioned aqueous dispersible Copolymerized polyester resin with metal sulfonate base After stirring continuously until the resin block disappears, the aqueous resin dispersion is cooled to room temperature to obtain a uniform water-dispersible copolymerized polyester resin solution with a solid content concentration of 5.0% by mass. Furthermore, after dispersing 3 parts by mass of aggregated silica particles (manufactured by Fuji Silysia Co., Ltd., Sylysia 310) in 50 parts by mass of water, Sylysia 310 was added to 99.46 parts by mass of the above-mentioned water-dispersible copolymerized polyester resin liquid. 0.54 parts by mass of the aqueous dispersion liquid of 20 mass parts was added with stirring, and 20 parts by mass of water was added to obtain an adhesion-modified coating liquid.

(Manufacturing Example 4 - Preparation of High Refractive Index Coating Agent)

Add 80 parts of methyl methacrylate, 20 parts of methacrylic acid, 1 part of azoisobutyronitrile, and 200 parts of isopropanol into the reaction vessel, and react at 80°C for 7 hours under a nitrogen environment to obtain a polymer with a weight average molecular weight of 30,000. solution of isopropanol. The obtained polymer solution was further diluted with isopropanol to a solid content of 5%, to obtain an acrylic resin solution B. Next, the obtained acrylic resin solution B was mixed with the following components to obtain a coating solution for forming a high refractive index layer.

(Manufacturing Example 5 - Preparation of Low Refractive Index Coating Agent)

2,2,2-trifluoroethyl acrylate (45 parts by mass), perfluorooctylethyl acrylate (45 parts by mass), acrylic acid (10 parts by mass), azoisobutyronitrile (1.5 parts by mass), formaldehyde Methyl ethyl ketone (200 parts by mass) was added to the reaction container, and reacted at 80° C. for 7 hours under a nitrogen atmosphere to obtain a methyl ethyl ketone solution of a polymer having a weight average molecular weight of 20,000. The obtained polymer solution was diluted with methyl ethyl ketone until the solid content concentration was 5% by mass to obtain a fluoropolymer solution C. The obtained fluoropolymer solution C was mixed as follows to obtain a coating liquid for forming a low refractive index layer.

(Manufacturing Example 6-Adjustment of Antiglare Layer Coating Agent-1)

Make acrylic acid copolymer CYCLOMER-P ACA-Z250 (manufactured by Daicel Chemical Industry Co., Ltd.) (49 parts by mass) containing unsaturated double bonds, cellulose acetate propionate CAP482-20 (number average molecular weight 75000) (Eastman Chemical Company) Manufactured) (3 parts by mass), acrylic acid monomer AYARAD DPHA (manufactured by Nippon Kayaku Co., Ltd.) (49 parts by mass), acrylic acid-styrene copolymer (average particle diameter 4.0 μm) (manufactured by Sekisui Chemical Industry Co., Ltd.) (2 mass parts parts) and IRGACURE 184 (manufactured by BASF) (10 parts by mass) with a solid content of 35% by mass were added to a mixed solvent of methyl ethyl ketone: 1-butanol = 3:1 to obtain a coating for forming an antiglare layer liquid.

(Manufacturing Example 7-Adjustment of Antiglare Layer Coating Agent-2)

Acrylic acid copolymer CYCLOMER-P ACA-Z250 (made by Daicel Chemical Industry Co., Ltd.) (49 parts by mass) containing unsaturated double bonds, cellulose acetate propionate CAP482-0.5 (number average molecular weight 25000) (Eastman Chemical Company) Manufactured) (3 parts by mass), acrylic acid monomer AYARAD DPHA (manufactured by Nippon Kayaku Co., Ltd.) (49 parts by mass), acrylic acid-styrene copolymer (average particle diameter 4.0 μm) (manufactured by Sekisui Chemical Industry Co., Ltd.) (4 mass parts) parts) and IRGACURE 184 (manufactured by BASF) (10 parts by mass) with a solid content of 35% by mass were added to a mixed solvent of methyl ethyl ketone: 1-butanol = 3:1 to obtain a coating for forming an antiglare layer liquid.

(Manufacturing Example 8-Adjustment of Coating Agent for Antiglare Layer-3)

Make acrylic acid copolymer CYCLOMER-P ACA-Z250 (manufactured by Daicel Chemical Industry Co., Ltd.) (49 parts by mass) containing unsaturated double bonds, cellulose acetate propionate CAP482-0.2 (number average molecular weight 15000) (Eastman Chemical Company) Manufactured) (3 parts by mass), acrylic acid monomer AYARAD DPHA (manufactured by Nippon Kayaku Co., Ltd.) (49 parts by mass), acrylic acid-styrene copolymer (average particle diameter 4.0 μm) (manufactured by Sekisui Chemical Industry Co., Ltd.) (2 mass parts parts) and IRGACURE 184 (manufactured by BASF) (10 parts by mass) with a solid content of 35% by mass were added to a mixed solvent of methyl ethyl ketone: 1-butanol = 3:1 to obtain a coating for forming an antiglare layer liquid.

(Polarizer Protective Film 1A)

90 parts by mass of PET (A) resin pellets containing no particles and 10 parts by mass of PET (B) resin pellets containing ultraviolet absorbers as raw materials for the intermediate layer of the base film were dried under reduced pressure at 135°C (1 Torr) for 6 After 1 hour, it was supplied to the extruder 2 (for the middle 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 layer) respectively, and in Dissolution was performed at 285°C. The 2 kinds of polymers are respectively filtered with stainless steel sintered filter media (rated filtration precision 10μm particles 95% cut), and laminated with 2 kinds of 3-layer confluence blocks, extruded into flakes from a die, and then electrostatically Apply the casting method, wrap it on a casting drum with a surface temperature of 30°C, cool and solidify, and make an unstretched film. At this time, the discharge rate of each extruder was adjusted so that the thickness ratio of the I layer, II layer, and III layer might become 10:80:10.

Next, apply the above-mentioned adhesion-modifying coating liquid on both sides of the unstretched PET film by the reverse roll method so that the coating amount after drying becomes 0.08 g/m ² , and then dry at 80°C for 20 seconds. .

The unstretched film forming the coating layer was led to a tenter stretcher, and while holding the end of the film with clips, it was led to a hot air zone at a temperature of 125° C., and stretched 4.0 times in the width direction. Next, while maintaining the width extending in the width direction, it was treated at a temperature of 225° C. for 10 seconds, and a 3.0% relaxation treatment was performed in the width direction to obtain a uniaxially stretched PET film with a film thickness of about 100 μm.

On one of the coated surfaces of the uniaxially stretched PET film, the coating solution for forming a high-refractive index layer was coated and dried at 150° C. for 2 minutes to form a high-refractive index layer with a film thickness of 0.1 μm. On this high-refractive-index layer, apply the coating solution for forming a low-refractive-index layer obtained by the above method, and dry at 150°C for 2 minutes to form a low-refractive-index layer with a film thickness of 0.1 μm, thereby obtaining a polarizer protection laminated antireflection layer. Film 1A.

(Polarizer protective film 2A)

Except for changing the line speed and changing the thickness of the unstretched film, the film was formed in the same manner as the polarizer protective film 1A to obtain a polarizer protective film 2A with a laminated antireflection layer film thickness of about 80 μm.

(Polarizer protective film 3A)

Except for changing the line speed and changing the thickness of the unstretched film, a film was formed in the same manner as the polarizer protective film 1A to obtain a polarizer protective film 3A with a laminated antireflection layer film thickness of about 60 μm.

(Polarizer protective film 4A)

Except for changing the line speed and changing the thickness of the unstretched film, the film was formed in the same manner as the polarizer protective film 1A to obtain a polarizer protective film 4A with a laminated antireflection layer film thickness of about 40 μm.

(Polarizer protective film 5A)

The unstretched film produced by the same method as polarizer protective film 1A was heated to 105°C, and then extend 3.3 times in the moving direction with a group of rollers with a difference in peripheral speed, then guide it to the hot air zone with a temperature of 130°C, and extend 4.0 times in the width direction, using the same method as the polarizer protective film 1A, to obtain A polarizer protective film 5A in which the film thickness of the laminated antireflection layer is about 30 μm.

(Polarizer protective film 6A)

Except not providing an antireflection layer, it produced by the same method as polarizer protective film 1A, and obtained polarizer protective film 6A with a film thickness of about 100 micrometers.

(Polarizer protective film 7A)

An antiglare layer coating agent was applied to one of the coated surfaces of the polarizer protective film prepared in the same manner as the polarizer protective film 2A except that the antireflection layer was not provided so that the film thickness after curing became 8 μm. -1, and oven dried at 80°C for 60 seconds. Thereafter, an ultraviolet irradiation device (Fusion UV Systems Japan, light source H bulb) was used to irradiate ultraviolet rays with an irradiation dose of 300 mJ/cm ² to laminate an anti-glare layer. Thereafter, an antireflection layer was laminated on the antiglare layer in the same manner as for the polarizer protective film 1A to obtain a polarizer protective film 7A.

(Polarizer protective film 8A)

Except that the anti-reflection layer is not provided, the anti-glare layer and the anti-reflection layer are laminated in the same way as the polarizer protective film 7A on one coated surface of the polarizer protective film produced by the same method as the polarizer protective film 3A. layer to obtain a polarizer protective film 8A.

(Polarizer Protective Film 9A)

An anti-glare layer coating agent was applied to one of the coated surfaces of the polarizer protective film produced in the same manner as the polarizer protective film 4A except that the antireflection layer was not provided so that the film thickness after curing became 8 μm. -2, and oven-dried at 80°C for 60 seconds. Thereafter, an ultraviolet irradiation device (Fusion UV Systems Japan, light source H bulb) was used to irradiate ultraviolet rays with an irradiation dose of 300 mJ/cm ² to laminate an anti-glare layer. Thereafter, an antireflection layer was laminated on the antiglare layer in the same manner as the polarizer protective film 1A to obtain a polarizer protective film 9A.

(Polarizer protective film 10A)

Except that the anti-reflection layer is not provided, the anti-glare layer and the anti-reflection layer are laminated in the same way as the polarizer protective film 7A on one coated surface of the polarizer protective film produced by the same method as the polarizer protective film 5A. layer to obtain a polarizer protective film 10A (with no anti-reflection layer laminated).

(Polarizer protective film 11A)

An antiglare layer coating agent was applied to one of the coated surfaces of the polarizer protective film produced in the same manner as the polarizer protective film 1A except that the antireflection layer was not provided so that the film thickness after curing became 8 μm. -3, and oven dried at 80°C for 60 seconds. Thereafter, an ultraviolet irradiation device (Fusion UV Systems Japan, light source H bulb) was used to irradiate ultraviolet rays with an irradiation dose of 300 mJ/cm ² to obtain a polarizer protective film 11A with an anti-glare layer.

(Polarizer protective film 12A)

An antiglare layer coating agent was applied to one of the coated surfaces of the polarizer protective film prepared in the same manner as the polarizer protective film 2A except that the antireflection layer was not provided so that the film thickness after curing became 8 μm. -1, and oven dried at 80°C for 60 seconds. Thereafter, an ultraviolet irradiation device (Fusion UV Systems Japan, light source H bulb) was used to irradiate ultraviolet rays with an irradiation dose of 300 mJ/cm ² to laminate an anti-glare layer. Thereafter, a low-refractive index layer was laminated on the anti-glare layer in the same manner as the polarizer protective film 1A. A polarizer protective film 12A in which a low reflection layer was laminated on an antiglare layer was obtained as described above.

(Polarizer Protective Film 1B)

90 parts by mass of PET (A) resin pellets containing no particles and 10 parts by mass of PET (B) resin pellets containing ultraviolet absorbers as raw materials for the intermediate layer of the base film were dried under reduced pressure at 135°C (1 Torr) for 6 After 1 hour, it was supplied to the extruder 2 (for the middle 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 layer) respectively, and in Dissolution was performed at 285°C. The 2 kinds of polymers are respectively filtered with stainless steel sintered filter media (rated filtration precision 10μm particles 95% cut), and laminated with 2 kinds of 3-layer confluence blocks, extruded into flakes from a die, and then electrostatically Apply the casting method, wrap it on a casting drum with a surface temperature of 30°C, cool and solidify, and make an unstretched film. At this time, the discharge rate of each extruder was adjusted so that the thickness ratio of the I layer, II layer, and III layer might become 10:80:10.

Next, apply the above-mentioned adhesion-modifying coating liquid on both sides of the unstretched PET film by the reverse roll method so that the coating amount after drying becomes 0.08 g/m ² , and then dry at 80°C for 20 seconds. .

The unstretched film forming the coating layer was led to a tenter stretcher, and while holding the end of the film with clips, it was led to a hot air zone at a temperature of 125° C., and stretched 4.0 times in the width direction. Next, while keeping the width extending in the width direction, it was treated at a temperature of 225° C. for 10 seconds, and a 3.0% relaxation treatment was performed in the width direction to obtain a polarizer protective film 1B of a uniaxially stretched PET film with a film thickness of about 100 μm.

(Polarizer protective film 2B)

Except for changing the line speed and changing the thickness of the unstretched film, the film was formed in the same manner as the polarizer protective film 1B to obtain the polarizer protective film 2B of a uniaxially stretched PET film with a film thickness of about 80 μm.

(Polarizer protective film 3B)

Except for changing the line speed and changing the thickness of the unstretched film, the film was formed in the same manner as the polarizer protective film 1B to obtain the polarizer protective film 3B of a uniaxially stretched PET film with a film thickness of about 60 μm.

(Polarizer Protective Film 4B)

Except for changing the line speed and changing the thickness of the unstretched film, the film was formed in the same manner as the polarizer protective film 1B to obtain the polarizer protective film 4B of a uniaxially stretched PET film with a film thickness of about 40 μm.

(Polarizer protective film 5B)

Except for changing the line speed and changing the thickness of the unstretched film, the film was formed in the same manner as the polarizer protective film 1B to obtain the polarizer protective film 5B of a uniaxially stretched PET film with a film thickness of about 20 μm.

(Polarizer protective film 6B)

Except for changing the line speed and changing the thickness of the unstretched film, the film was formed in the same manner as the polarizer protective film 1B to obtain the polarizer protective film 6B of a uniaxially stretched PET film with a film thickness of about 150 μm.

Using polarizer protective films 1A to 12A and 1B to 6B, a liquid crystal display device was produced as described below.

(Example 1)

A polarizer protective film 1A was attached to one side of the polarizer containing PVA and iodine so that the transmission axis of the polarizer and the fast axis of the film were perpendicular. At this time, a polarizer is laminated on the surface of the polarizer protective film 1A on which the antireflection layer is not laminated. Also, a TAC film (manufactured by Fuji Film Co., Ltd., thickness 80 μm) was attached to the opposite surface of the polarizer. Polarizing plate 1A was fabricated as described above. Similarly, on one side of the polarizer comprising PVA and iodine, the polarizer protective film 1B is attached so that the absorption axis of the polarizer and the slow axis of the film are perpendicular, and the TAC film ( Fuji Film Co., Ltd. product, thickness 80 micrometers), and the polarizing plate 1B was produced. BRAVIA KDL-40W920A manufactured by SONY (with The polarizing plate on the identification side of the light source that emits the excitation light and the liquid crystal display device of the backlight light source of the quantum dot) is replaced by a polarizing plate 1A, and the polarizing plate on the light source side is replaced by a polarizing plate 1B. At this time, the polarizer protective film 1A and the polarizer protective film 1B are disposed so that the polarizer protective film 1A and the polarizer protective film 1B are on the opposite side (far end) from the liquid crystal, respectively. Also, the direction of the transmission axis of the polarizing plate 1A and the polarizing plate 1B is made to be the same as the direction of the transmission axis of the polarizing plate before replacement. A liquid crystal display device was fabricated as described above.

(Example 2)

Except having replaced the polarizer protective film 1A with the polarizer protective film 2A, it carried out similarly to Example 1, and produced the liquid crystal display device.

(Example 3)

Except having replaced the polarizer protective film 1A with the polarizer protective film 3A, it carried out similarly to Example 1, and produced the liquid crystal display device.

(Example 4)

Except having replaced the polarizer protective film 1A with the polarizer protective film 4A, it carried out similarly to Example 1, and produced the liquid crystal display device.

(Example 5)

A liquid crystal display device was produced in the same manner as in Example 1 except that the polarizer protective film 4A was used instead of the polarizer protective film 1A, and its fast axis was parallel to the transmission axis of the polarizer.

(Example 6)

Except having replaced the polarizer protective film 1A with the polarizer protective film 7A, it carried out similarly to Example 1, and produced the liquid crystal display device.

(Example 7)

Except having replaced the polarizer protective film 1A with the polarizer protective film 8A, it carried out similarly to Example 1, and produced the liquid crystal display device.

(Embodiment 8)

Except having replaced the polarizer protective film 1A with the polarizer protective film 9A, it carried out similarly to Example 1, and produced the liquid crystal display device.

(Example 9)

Except having replaced the polarizer protective film 1A with the polarizer protective film 12A, it carried out similarly to Example 1, and produced the liquid crystal display device.

(comparative example 1)

Except having replaced the polarizer protective film 1A with the polarizer protective film 5A, it carried out similarly to Example 1, and produced the liquid crystal display device.

(comparative example 2)

Except having replaced the polarizer protective film 1A with the polarizer protective film 6A, it carried out similarly to Example 1, and produced the liquid crystal display device.

(comparative example 3)

Except having replaced the polarizer protective film 1A with the polarizer protective film 10A, it carried out similarly to Example 1, and produced the liquid crystal display device.

(comparative example 4)

Except having replaced the polarizer protective film 1A with the polarizer protective film 11A, it carried out similarly to Example 1, and produced the liquid crystal display device.

(Example 10)

Except having replaced the polarizer protective film 1B with the polarizer protective film 2B, it carried out similarly to Example 1, and produced the liquid crystal display device.

(comparative example 5)

Except having replaced the polarizer protective film 1B with the polarizer protective film 3B, it carried out similarly to Example 1, and produced the liquid crystal display device.

(comparative example 6)

Except having replaced the polarizer protective film 1B with the polarizer protective film 4B, it carried out similarly to Example 1, and produced the liquid crystal display device.

(comparative example 7)

Except having replaced the polarizer protective film 1B with the polarizer protective film 5B, it carried out similarly to Example 1, and produced the liquid crystal display device.

(Example 11)

Except having replaced the polarizer protective film 1B with the polarizer protective film 6B, it carried out similarly to Example 1, and produced the liquid crystal display device.

(Example 12)

A liquid crystal display device was manufactured in the same manner as in Example 1 except that BRAVIA KDL-40W920A manufactured by SONY Corporation was replaced with BRAVIA KDL-42W900B manufactured by SONY Corporation.

(Example 13)

Except having replaced the polarizer protective film 1B with the polarizer protective film 2B, it carried out similarly to Example 12, and produced the liquid crystal display device.

(Example 14)

Except having replaced the polarizer protective film 1B with the polarizer protective film 3B, it carried out similarly to Example 12, and produced the liquid crystal display device.

(Example 15)

Except having replaced the polarizer protective film 1B with the polarizer protective film 4B, it carried out similarly to Example 12, and produced the liquid crystal display device.

(comparative example 8)

Except having replaced the polarizer protective film 1B with the polarizer protective film 5B, it carried out similarly to Example 12, and produced the liquid crystal display device.

(Example 16)

Except having replaced the polarizer protective film 1B with the polarizer protective film 6B, it carried out similarly to Example 12, and produced the liquid crystal display device.

(Example 17)

A liquid crystal display device was manufactured in the same manner as in Example 1 except that BRAVIA KDL-40W920A manufactured by SONY Corporation was replaced with BRAVIA KDL-55W900A manufactured by SONY Corporation.

(comparative example 9)

Except having replaced the polarizer protective film 1B with the polarizer protective film 2B, it carried out similarly to Example 17, and produced the liquid crystal display device.

(comparative example 10)

Except having replaced the polarizer protective film 1B with the polarizer protective film 3B, it carried out similarly to Example 17, and produced the liquid crystal display device.

(comparative example 11)

Except having replaced the polarizer protective film 1B with the polarizer protective film 4B, it carried out similarly to Example 17, and produced the liquid crystal display device.

(comparative example 12)

Except having replaced the polarizer protective film 1B with the polarizer protective film 5B, it carried out similarly to Example 17, and produced the liquid crystal display device.

(Example 18)

Except having replaced the polarizer protective film 1B with the polarizer protective film 6B, it carried out similarly to Example 17, and produced the liquid crystal display device.

(Example 19)

On one side of the polarizer comprising PVA and iodine, the polarizer protective film 2B was attached so that the absorption axis of the polarizer and the slow axis of the film became parallel, and a TAC film (Fuji Film (Co., Ltd., thickness: 80 μm), and a polarizing plate 2B was produced. Except having used the polarizing plate 2B instead of the polarizing plate 1B, it carried out similarly to Example 1, and produced the liquid crystal display device.

(Example 20)

On one side of the polarizer comprising PVA and iodine, the polarizer protective film 1 is attached so that the absorption axis of the polarizer is parallel to the slow axis of the film, and a TAC film (Fuji Film (stock) company make, thickness 80 micrometers), and the polarizing plate 1B' was produced. A liquid crystal display device was produced in the same manner as in Example 1 except for using the aforementioned alternative polarizing plate 1B.

Table 1 shows the physical properties of polarizer protective films 1A to 12A.

Table 1 shows the physical properties of polarizer protective films 1B to 6B.

The wavelength of the peak top of the peak that exists in the wavelength range of 600nm to 780nm of the liquid crystal display device BRAVIA KDL-40W920A, BRAVIA KDL-42W900B, and BRAVIA KDL-55W900A (Rx) and its half-value width (Ry), the wavelength (Gx) and its half-value width (Gy) of the top of the peak existing in the wavelength range from 495nm to 600nm, and the wavelength range from 400nm to 495nm Table 3 shows the wavelength (Bx) of the top of the peak and its half-width (By) of the peak.

Table 4 shows the results of evaluating the iris observation of the liquid crystal display devices of the respective examples.

[industrial availability]

The liquid crystal display device and the polarizing plate of the present invention can ensure good visibility and significantly suppress the occurrence of iridescent stains at any angle, and make great contributions to the industry.

Claims (12)

A liquid crystal display device, which is a liquid crystal display device with a backlight source, a light source side polarizer, a liquid crystal cell, and a recognition side polarizer; wherein the backlight source is between 400nm and less than 495nm, between 495nm and less than 600nm, and between 600nm and 780nm Each wavelength region has a peak top of the luminescent spectrum, and the half-maximum width of each peak is more than 5nm; the identification side polarizer includes a polyester film A with an in-plane retardation of 1500-30000nm, and at least one side of the polyester film A Laminated anti-reflection layer and/or low-reflection layer; the polarizer on the light source side includes polyester film B; when the in-plane retardation of polyester film B is defined as Re _B , the wavelength of 600nm to 780nm that exists in the backlight source Ry/[Rx/(Re _B /Rx)] is 0.55 or more when the wavelength of the peak top of the peak in the region is defined as Rx, and the half-value width is defined as Ry. The liquid crystal display device according to claim 1, wherein the wavelength of the peak top of the peak existing in the wavelength region of 400nm or more and less than 495nm is defined as Bx, the half-maximum width is defined as By, and the wavelength of the peak existing in the range of 495nm or more and less than 600nm is defined as Bx. Gx is the wavelength of the peak top of the peak in the wavelength region, and when the half-width is Gy, By/[Bx/(Re _B /Bx)] is 0.55 or more, and Gy/[Gx/(Re _B / Gx)] is 0.55 or more. The liquid crystal display device according to claim 1 or 2, wherein the Rx is 630 nm or more. The liquid crystal display device according to claim 1 or 2, wherein the Ry is 180 nm or less. The liquid crystal display device according to claim 1 or 2, wherein the light source includes a light source emitting excitation light and quantum dots. The liquid crystal display device according to claim 1 or 2, wherein in the polarizing plate on the light source side, the direction of the absorption axis of the polarizing plate and the direction of the slow axis of the polyester film B are perpendicular to ±15° or less. The liquid crystal display device according to claim 1 or 2, wherein the in-plane retardation (Re _B ) of the polyester film B is not less than 6000 nm and not more than 10000 nm. The liquid crystal display device according to claim 1 or 2, wherein the polyester film B has a ratio (Re _B /Rth _B ) of in-plane retardation (Re _B ) to thickness direction retardation (Rth _B ) of 0.6 to 1.2. The liquid crystal display device according to claim 1 or 2, wherein the value of the refractive index (Ny) in the direction of the slow axis of the polyester film B - the refractive index in the direction perpendicular to the slow axis (Nx) is 0.1 or more. The liquid crystal display device according to claim 1 or 2, wherein the polyester film B has a thickness of not less than 60 μm and not more than 100 μm. The liquid crystal display device according to claim 1 or 2, wherein the polyester film B is a polyethylene terephthalate film. The liquid crystal display device according to claim 1 or 2, wherein the surface reflectance of the surface of the antireflection layer at a wavelength of 550 nm is 2.0% or less.

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