TWI787938B - Liquid crystal display device - Google Patents

Abstract

Provide a kind of liquid crystal display device, just have the peak top ( peak top), and the half maximum width of the peak in the red region (600nm to 780nm) is relatively narrow, even if a polyester film is used as a polarizer protective film, it can suppress rainbow spots. A liquid crystal display device having a backlight light source, two polarizers, and a liquid crystal cell disposed between the two polarizers, the backlight light source having a thickness of more than 400nm and less than 495nm, more than 495nm and less than 600nm, and more than 600nm and less than 780nm Each wavelength region has a peak top of the luminescence spectrum, and the half-maximum width of the peak with the highest peak intensity in the wavelength region between 600nm and 780nm is less than 5nm. At least one of the aforementioned polarizers is polarized The plate is made of a polyester film laminated on at least one side of the polarizer. The polyester film has a retardation of 1500-30000 nm, and an antireflection layer and/or a low reflection layer is laminated on at least one side of the polyester film.

Description

Liquid crystal display device

The present invention relates to a liquid crystal display device and a polarizing plate. More specifically, it relates to a liquid crystal display device and a polarizing plate capable of reducing the occurrence of iridescent unevenness.

A polarizer used in a liquid crystal display (LCD) usually has a structure in which a polarizer dyed with iodine such as polyvinyl alcohol (PVA) is sandwiched between two polarizer protective films, and triacetate fiber is usually used as the polarizer protective film prime (TAC) film. In recent years, along with the thinning of LCDs, the thinning of polarizing plates has been demanded. However, if the thickness of the TAC film used as a protective film is thinned for this reason, sufficient mechanical strength cannot be obtained, and there arises a problem that moisture permeability deteriorates. In addition, TAC films are very expensive, so polyester films have been proposed as inexpensive alternatives (Patent Documents 1 to 3), but there is a problem of iridescent stains.

When a birefringent oriented polyester film is arranged on one side of the polarizer, the linearly polarized light emitted from the backlight unit or the polarizer passes through the polyester film, and the polarization state changes. The transmitted light exhibits an interference color specific to the retardation of the birefringence-thickness product of the aligned polyester film. Therefore, if a discontinuous luminescent spectrum such as a cold cathode tube or a hot cathode tube is used as a light source, different transmitted light intensities will be displayed depending on the wavelength, and a rainbow-like color spot will be formed (see: Proceedings of the 15th Micro-Optics Conference, No. 30-31 pages).

As a means to solve the above problems, it is proposed to use a white light source with a continuous and wide emission spectrum as a white light-emitting diode as a backlight source, and also use an aligned polyester film with a certain retardation as a polarizer protective film (patent Document 4). White light-emitting diodes have a continuous and broad emission spectrum in the visible region. Therefore, it is proposed that if we focus on the envelope shape of the interference color spectrum produced by the transmitted light passing through the birefringent body, we can obtain a spectrum similar to the light emission spectrum of the light source by controlling the retardation of the aligned polyester film. Suppresses iridescence.

In addition, by making the alignment direction of the alignment polyester film perpendicular or parallel to the polarization direction of the polarizer, even if the linearly polarized light emitted from the polarizer passes through the alignment polyester film, it can pass through while maintaining the polarization state. In addition, the birefringence of the oriented polyester film is controlled to improve the uniaxial alignment, so that the light incident from an oblique direction can also pass through while maintaining the polarized state. When the aligned polyester film is viewed from an oblique direction, 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 from an oblique direction becomes smaller. Therefore, it is considered that the deviation between the direction of the linearly polarized light and the direction of the main axis of alignment becomes small, and it becomes difficult to change the polarization state. In this way, it is considered that by controlling the light emission spectrum of the light source, the alignment state of the birefringent body, and the direction of the alignment axis, the change of the polarization state can be controlled, and the visibility is significantly improved without rainbow-like stains. [Prior Art Literature] [Patent Document]

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

[Problem to be solved by the invention]

In recent years, the demand for expanding the color gamut of liquid crystal display devices has increased, so the use of white light-emitting diodes (for example, with blue light-emitting diodes, and at least K ₂ SiF ₆ : Mn ⁴⁺ as phosphors) has been developed. A liquid crystal display device for a backlight source such as a white light-emitting diode of a fluoride phosphor, etc.), the white light-emitting diode has a blue region (above 400nm and less than 495nm), a green region (above 495nm and less than 600nm) Each wavelength region of the red region (600nm to 780nm) has a peak top (peak top) of the emission spectrum, and the half maximum width of the peak in the red region (600nm to 780nm) is narrow (less than 5nm) emission spectrum .

When industrially producing a liquid crystal display device using a polarizing plate using a polyester film as a polarizer protective film, it is usually arranged so that the transmission axis of the polarizer and the fast axis of the polyester film are perpendicular to each other. This is because when the polyvinyl alcohol film of the polarizer is manufactured by longitudinal uniaxial stretching, the polyester film of the protective film is manufactured by longitudinal stretching and then lateral stretching, so that the polyester film is aligned with the main axis. The direction is the horizontal direction, and when these strips are laminated to manufacture a polarizing plate, the fast axis of the polyester film and the transmission axis of the polarizing plate are usually perpendicular to each other. It was found that in this case, by using an aligned polyester film having a specific retardation as the polyester film, the method of using, for example, a light-emitting element including a combined blue light-emitting diode and a yttrium-aluminum-garnet-based yellow phosphor When a light source with a continuous and wide emission spectrum represented by a white LED is used as a backlight source, the rainbow-like color spots are greatly improved, but the half-maximum width including peaks in the red region (600nm to 780nm) is used. In the case of a backlight light source of a white light-emitting diode with a narrow (less than 5nm) emission spectrum, there is still a new problem of rainbow spots.

That is, the object of the present invention is to provide a liquid crystal display device and a polarizing plate, which have a blue region (above 400nm and less than 495nm), a green region (above 495nm and less than 600nm) and a red region (above 600nm and less than 780nm). The liquid crystal display device of the backlight source of the white light-emitting diode with a light-emitting spectrum with a light-emitting spectrum peak top in each wavelength region (600nm to 780nm) and a narrow half-maximum width (less than 5nm) Among them, rainbow spots can be suppressed even when a polyester film is used as a polarizer protective film. [Means to solve the problem]

Representative inventions are as follows. item 1 A liquid crystal display device has a backlight source, two polarizers, and a liquid crystal cell arranged between the aforementioned two polarizers, The above-mentioned backlight light source has a peak of the emission spectrum in each wavelength region of 400nm to less than 495nm, 495nm to less than 600nm, and 600nm to 780nm, respectively, and the peak intensity in the wavelength region of 600nm to 780nm is the highest. White light-emitting diodes with a light-emitting spectrum with a full width at half maximum of less than 5 nm, Among the aforementioned polarizers, at least one polarizer is laminated with a polyester film on at least one side of the polarizer, The polyester film has a retardation of 1500 to 30000 nm, and an antireflection layer and/or a low reflection layer is laminated on at least one side of the polyester film. item 2 The liquid crystal display device as described in Item 1, wherein the emission spectrum of the aforementioned backlight light source is The half-maximum width of the peak with the highest peak intensity in the wavelength region of 400 nm or more and less than 495 nm is 5 nm or more, The full width at half maximum of the peak with the highest peak intensity in the wavelength range from 495 nm to less than 600 nm is 5 nm or more. item 3 The liquid crystal display device according to item 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. Item 4 A polarizing plate for a liquid crystal display device, which is a polarizing plate with a polyester film laminated on at least one side of the polarizer, the polyester film has a retardation of 1500 to 30000 nm, and an antireflection layer is laminated on at least one side of the polyester film and/or low reflection layer, The liquid crystal display device has a backlight light source including a white light emitting diode, and the white light emitting diode has peak tops of emission spectra in each wavelength region of 400 nm to less than 495 nm, 495 nm to less than 600 nm, and 600 nm to 780 nm. , and the emission spectrum in which the half maximum width of the peak with the highest peak intensity in the wavelength region of 600 nm to 780 nm is less than 5 nm. Item 5 The polarizing plate according to item 4, wherein the surface reflectance of the surface of the antireflection layer at a wavelength of 550 nm is 2.0% or less. [Effect of Invention]

The liquid crystal display device and the polarizing plate of the present invention can ensure good visibility with effectively suppressed occurrence of rainbow-like stains at any viewing angle.

[Mode for Carrying Out the Invention]

Generally speaking, a liquid crystal display device is sequentially composed of a rear module, a liquid crystal cell and a front module from the side opposite to the backlight source to the side where images are displayed (visible 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. Here, the polarizing plate is arranged on the side facing the backlight light source in the rear module, and is arranged on the side where images are displayed (visible side) in the front module.

The liquid crystal display device of the present invention has at least a backlight light source and a liquid crystal cell disposed between two polarizing plates as structural components.

In addition, in addition to the backlight source, polarizer, and liquid crystal cell, the liquid crystal display device may also have other structures, such as color filters, galvanized films, diffusers, anti-reflection films, and the like. A brightness-enhancing film can be arranged between the polarizing plate on the light source side and the backlight light source. As a brightness improvement film, the reflective polarizing plate which transmits one linearly polarized light and reflects the linearly polarized light orthogonal to it is mentioned, for example. 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 such that the absorption axis of the reflective polarizing plate is parallel to the absorption axis of the light source side polarizing plate.

烯系薄膜所代表的沒有雙折射的薄膜(3層結構的偏光板)，但未必需要在偏光片的另一面上積層薄膜(2層結構的偏光板)。又，在使用聚酯薄膜作為偏光片兩側的保護薄膜的情況下，較佳為兩片聚酯薄膜的慢軸相互約略平行。Among the two polarizers arranged in the liquid crystal display device, at least one polarizer is made by laminating a polyester film on at least one side of a polarizer dyed with iodine such as polyvinyl alcohol (PVA). In the present invention, from the viewpoint of suppressing rainbow-like stains, the polyester film has a specific retardation, and an antireflection layer and/or a low reflection layer is laminated on at least one side of the polyester film. The antireflection layer and/or the low reflection layer may be provided on the surface of the polyester film opposite to the surface on which the polarizer is laminated, or may be provided on the surface of the polyester film on which the polarizer is laminated, or may be provided on both sides. . It is preferable to provide an antireflection layer and/or a low reflection layer on the surface of the polyester film opposite to the surface on which the polarizer is laminated. When the antireflection layer and/or the low reflection layer are provided on the surface of the polyester film on which the polarizer is laminated, the antireflection layer and/or the low reflection layer are preferably provided between the polyester film and the polarizer. In addition, other layers (for example, easy-adhesive layer, hard coat layer, antiglare layer, antistatic layer, antifouling layer, etc.) may exist between the antireflection layer and/or low reflection layer, and the polyester film. The refractive index of the polyester film in a direction parallel to the transmission axis of the polarizer is preferably 1.53 to 1.62 from the viewpoint of further suppressing iridescent unevenness. On the other side of the polarizer, it is preferable to laminate such as TAC film or acrylic film,

Films without birefringence represented by ethylenic films (three-layer polarizing plate), but it is not necessarily necessary to laminate a film on the other side of the polarizer (two-layer polarizing plate). Moreover, when using a polyester film as a protective film on both sides of a polarizer, it is preferable that the slow axes of two polyester films are mutually substantially parallel.

As the polarizer, any polarizer (polarizing film) used in this technical field can be appropriately selected and used. Typical polarizers include polyvinyl alcohol films or the like stained with dichroic materials such as iodine, but not limited thereto, and conventionally known polarizers that may be developed in the future can be appropriately selected and used.

Commercially available products can be used for the PVA film, for example, "KURARAY VINYLON (manufactured by Kuraray Co., Ltd.)", "TOHCELLO VINYLON (manufactured by TOHCELLO Co., Ltd.)", "Nichigo Vinylon (manufactured by Nippon Gosei Chemical Co., Ltd.)" and the like can be used. . Examples of dichroic materials include iodine, diazo compounds, polymethine dyes, and the like.

The polarizer can be obtained by any method. For example, it can be obtained by uniaxially stretching a PVA film dyed with a dichroic material in an aqueous solution of boric acid, washing and drying while maintaining the stretched state. The draw ratio of uniaxial stretching is usually about 4 to 8 times, and is not particularly limited. Other manufacturing conditions can be appropriately set according to known methods.

As the structure of the backlight, it can be an edge light (edge light) mode as a structural member such as a light guide plate or a reflector plate, or it can be a directly below type mode. A backlight light source of a light-emitting diode, the white light-emitting diode has a peak top of the light-emitting spectrum in each wavelength region of 400nm to less than 495nm, 495nm to less than 600nm, and 600nm to 780nm, and 600nm to 780nm A light emission spectrum in which the half maximum width of the peak with the highest peak intensity in the wavelength region is less than 5 nm. It is known that the respective peak wavelengths of blue, green, and red defined in the CIE chromaticity diagram are 435.8 nm (blue), 546.1 nm (green), and 700 nm (red). The aforementioned wavelength regions of 400 nm to less than 495 nm, 495 nm to less than 600 nm, and 600 nm to 780 nm correspond to the blue region, the green region, and the red region, respectively. The upper limit of the full width at half maximum of the peak having the highest peak intensity in the wavelength region of 600 nm to 780 nm is preferably less than 5 nm, more preferably less than 4 nm, and still more preferably less than 3.5 nm. The lower limit is preferably at least 1 nm, more preferably at least 1.5 nm. Since the color gamut of a liquid crystal display device expands that the half width of a wave peak is less than 5 nm, it is preferable. Moreover, when the full width at half maximum of a wave peak is less than 1 nm, there exists a possibility that luminous efficiency may deteriorate. Considering the balance between the required color gamut and luminous efficiency, design the shape of the luminous spectrum. In addition, here, the full width at half maximum means the peak width (nm) at the intensity of 1/2 of the peak intensity at the peak top wavelength.

The application of a backlight light source having an emission spectrum having the above-mentioned characteristics to LCDs is a technology that has attracted attention in recent years due to increasing demands for expanding the color gamut. LEDs that use conventionally used white LEDs (for example, a light-emitting element that combines a blue light-emitting diode and a yttrium-aluminum-garnet-based yellow phosphor) as a backlight light source can only reproduce the spectrum recognizable by the human eye. About 20% of the color. On the other hand, in the case of using a backlight light source having an emission spectrum having the above characteristics, it can be said that more than 60% of colors can be reproduced.

The aforementioned wavelength region of 400 nm to less than 495 nm is more preferably 430 nm to 470 nm. The aforementioned wavelength region of 495 nm to less than 600 nm is more preferably 510 nm to 560 nm. The aforementioned wavelength range of 600 nm to 780 nm is more preferably 600 nm to 700 nm, and still more preferably 610 nm to 680 nm.

The full width at half maximum (the full width at half maximum of the peak having the highest peak intensity in each wavelength range) of the emission spectrum at the top of each wavelength range from 400 nm to less than 495 nm, and from 495 nm to less than 600 nm is not particularly limited, However, the half maximum width of the peak with the highest peak intensity in the wavelength region of 400nm or more and less than 495nm is preferably more than 5nm, and the half width of the peak with the highest peak intensity in the wavelength region of 495nm or more and less than 600nm is preferably Preferably, it is 5 nm or more. From the viewpoint of securing an appropriate color gamut, the peak half width at the top of each wavelength range from 400 nm to less than 495 nm, and from 495 nm to less than 600 nm (the half width of the peak with the highest peak intensity in each wavelength range The upper limit of height and width) is preferably less than 140nm, more preferably less than 120nm, more preferably less than 100nm, more preferably less than 80nm, more preferably less than 60nm, still more preferably less than 50nm.

Specific examples of a white light source having an emission spectrum having the above characteristics include a phosphor-type white light-emitting diode in which a blue light-emitting diode and a phosphor are combined. As the red phosphor among the aforementioned phosphors, for example, a fluoride phosphor having a composition formula of K ₂ SiF ₆ :Mn ⁴⁺ (also referred to as “KSF”) and others can be exemplified. The Mn ⁴⁺ activated fluoride complex fluorescent system is a phosphor that uses Mn ⁴⁺ as the activator and fluoride complex salts of alkali metals, amines or alkaline earth metals as the parent crystal. Among the fluoride complexes that form the parent crystal, there are those whose coordination centers are trivalent metals (B, Al, Ga, In, Y, Sc, Lanthanum), quadrivalent metals (Si, Ge, Sn, Ti, Zr, Re , Hf) and pentavalent metals (V, P, Nb, Ta), the number of fluorine atoms coordinated around them is 5-7.

A suitable example of Mn ⁴⁺ activated fluoride complex phosphor is A ₂ [MF ₆ ]: Mn (A is at least one selected from Li, Na, K, Rb, Cs, NH ₄ ; M is One or more selected from Ge, Si, Sn, Ti, Zr), E[MF ₆ ]: Mn (E is one or more selected from Mg, Ca, Sr, Ba, Zn; M is selected from Ge, Si, One or more selected from Sn, Ti, Zr), Ba _0.65 , Zr _0.35 F _2.70 : Mn, A ₃ [ZrF ₇ ]: Mn (A is selected from Li, Na, K, Rb, Cs, NH ₄ above), A ₂ [MF ₅ ]: Mn (A is one or more selected from Li, Na, K, Rb, Cs, NH ₄ ; M is one or more selected from Al, Ga, In), A ₃ [MF ₆ ]: Mn (A is at least one selected from Li, Na, K, Rb, Cs, NH ₄ ; M is at least one selected from Al, Ga, In), Zn ₂ [MF ₇ ]: Mn (M is one or more selected from Al, Ga, In), A[In ₂ F ₇ ]: Mn (A is one or more selected from Li, Na, K, Rb, Cs, NH ₄ ), etc.

One of the preferred Mn ⁴⁺ activated fluoride complex phosphors is A ₂ MF ₆ crystallized from alkali metal hexafluoro complex salts: Mn (A is from Li, Na, K, Rb, Cs, NH ₄ or more selected; M is selected from Ge, Si, Sn, Ti, Zr or more). Among them, preferably, A is one or more selected from K (potassium) or Na (sodium), and M is Si (silicon) or Ti (titanium). Among them, it is especially preferable that A is K (the ratio of K in the total amount of A is more than 99 mol%), and M is Si. The activating element, ideally Mn (manganese) is 100%, and may contain Ti, Zr, Ge, Sn, Al, Ga, B, In, Cr, Fe, Co, Ni, Cu, Nb, Mo, Ru, Ag, Zn, Mg, etc. When M is Si, the ratio of Mn in the total of Si and Mn is desirably in the range of 0.5 mol % to 10 mol %. As other preferred Mn ⁴⁺ activated fluoride complex phosphors, the chemical formula A _2+x M _y Mn _z F _n (A is Na and K; M is Si and Al; -1≦x ≦1 and 0.9≦y+z≦1.1 and 0.001≦z≦0.4 and 5≦n≦7).

As the backlight source, preferably a white light-emitting diode with a blue light-emitting diode and at least a fluoride phosphor as phosphor, particularly preferably with a blue light-emitting diode and as phosphor White LEDs of at least K ₂ SiF ₆ : Mn ⁴⁺ fluoride phosphors. For example, commercially available products such as NSSW306FT white LED manufactured by Nichia Chemical Industries, Ltd. can be used.

In addition, as the green phosphor among the aforementioned phosphors, for example, a Sialon-based phosphor with a basic composition of β-SiAlON:Eu, etc., a (Ba, Sr) ₂ SiO ₄ : Silicate-based phosphors with Eu etc. as the basic composition, others.

In addition, when there are multiple peaks in any one of the wavelength range of 400nm to less than 495nm, the wavelength range of 495nm to less than 600nm, or the wavelength range of 600nm to 780nm, it is considered as follows . When the plurality of peaks are independently independent peaks, it is preferable that the full width at half maximum of the peak with the highest peak intensity is within the above-mentioned range. In addition, for other peaks having an intensity of 70% or more of the highest peak intensity, it is a more preferable aspect that the full width at half maximum also falls within the above-mentioned range. For one independent peak having a shape in which plural peaks overlap, when the half maximum width of the peak with the highest peak intensity among the plural peaks can be directly measured, this half maximum width is used. Here, the independent peak means a region having an intensity equal to 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 whose intensity reaches 1/2 of the peak intensity on both sides, the plurality of peaks are regarded as one peak as a whole. For one peak having a shape in which a plurality of peaks overlap, the width (nm) of the peak at the intensity of 1/2 of the highest peak intensity among them is the full width at half maximum. Also, the peak with the highest peak intensity among the plurality of peaks is taken as the peak top. Also, the peak holding the highest peak intensity in each wavelength region of the wavelength region of 400nm or more and less than 495nm, the wavelength region of 495nm or more and less than 600nm, or the wavelength region of 600nm or more and 780nm or less is preferably compared with other wavelength regions. The crests have an independent relationship to each other. Particularly preferably, there is an intensity between 600nm and 780nm in the wavelength region between the peak having the highest peak intensity in the wavelength region of 495nm or more and less than 600nm, and the peak having the highest peak intensity in the region of 600nm or more and 780nm or less. It is preferable in terms of color vividness that a region having 1/3 of the peak intensity of the peak having the highest peak intensity exists in the wavelength region.

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

The inventors of the present invention carried out careful examination, and found that in the above-mentioned backlight light source, it is included in the blue region (above 400nm and less than 495nm), the green region (above 495nm and less than 600nm) and the red region (above 600nm and below 780nm) In the liquid crystal display device of the backlight source of the white light-emitting diode, which has a peak top of the light-emitting spectrum in each wavelength region, and the half-maximum width of the peak in the red region (above 600nm and below 780nm) is relatively narrow and less than 5nm, If a polyester film having an antireflection layer and/or a low reflection layer and having a specific retardation is used as a polarizer protective film, a liquid crystal display device and a polarizer capable of suppressing rainbow spots can be provided. As a mechanism for suppressing the occurrence of rainbow-like unevenness by utilizing the above-mentioned aspects, the following considerations are made.

When the aligned polyester film is disposed 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 factors for the change of the polarization state may be affected by the difference in refractive index at the interface between the air layer and the aligned polyester film, or the difference in refractive index at the interface between the polarizer and the aligned polyester film. When the linearly polarized light incident on the aligned polyester film passes through each interface, part of the light is reflected due to the difference in refractive index between the interfaces. At this time, both the outgoing light and the reflected light change the polarization state, and this is considered to be one of the factors causing the rainbow-like unevenness. Therefore, it can be considered that an anti-reflection layer or a low-reflection layer is provided on the surface of the oriented polyester film to reduce surface reflection, thereby suppressing the reflection at the interface between the air layer and the oriented polyester film, and suppressing rainbow-like stains.

According to the above, the present invention has peaks of emission spectra in each wavelength region included in the blue region (400nm or more and less than 495nm), the green region (495nm or more and less than 600nm) and the red region (600nm or more and 780nm or less) In the liquid crystal display device of the backlight light source of the white light-emitting diode, and the half maximum width of the peak in the red region (above 600nm and below 780nm) is relatively narrow and less than 5nm, even if a polyester film is used as a polarizer A polarizing plate without a protective film does not produce rainbow-like stains, and it becomes possible to have good visibility.

As for the polarizing plate, it is preferable that a polarizing plate protective film made of a polyester film is laminated on at least one side of the polarizing plate. Preferably, the polyester film used for the polarizer protective film has a retardation of 1,500 to 30,000. When the amount of retardation is within the above-mentioned range, it tends to be easier to reduce rainbow spots, which is preferable. The preferred lower limit of retardation is 3000nm, the better lower limit is 3500nm, the better lower limit is 4000nm, the better lower limit is 6000nm, and the better lower limit is 8000nm . A preferable upper limit is 30,000 nm, and a polyester film having a retardation larger than this becomes considerably thicker, and tends to lower handling properties as an industrial material. In this specification, the retardation means the in-plane retardation unless otherwise specified.

In addition, the retardation can be obtained by measuring the refractive index and the thickness in the biaxial direction, and can also be obtained by using a commercially available automatic birefringence measuring device called KOBRA-21ADH (Oji Scientific Instruments Co., Ltd.). Moreover, the refractive index can be calculated|required with the Abbe's refractometer (measurement wavelength 589nm).

The ratio (Re/Rth) of the retardation (Re: in-plane retardation) of the polyester film to the thickness direction retardation (Rth) is preferably 0.2 or more, more preferably 0.5 or more, still more preferably 0.6 or more. The larger the ratio (Re/Rth) of the above-mentioned retardation to the retardation in the thickness direction, the more isotropy of the birefringence effect increases, and the tendency of rainbow-like color spots depending on the viewing angle becomes less likely to occur. Since the ratio (Re/Rth) of the aforementioned retardation to the thickness direction retardation of a completely uniaxial (uniaxially symmetric) film is 2.0, the upper limit of the ratio (Re/Rth) of the aforementioned retardation to the thickness direction retardation is relatively small. The best is 2.0. In addition, the phase difference in the thickness direction means the average of the phase differences obtained by multiplying the two birefringences ΔNxz and ΔNyz when the film is viewed in cross-section in the thickness direction by the film thickness d.

The NZ coefficient of the polyester film is preferably at most 2.5, more preferably at most 2.0, still more preferably at most 1.8, and still more preferably at most 1.6, from the viewpoint of further suppressing iridescent unevenness. Since the NZ coefficient becomes 1.0 for 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 tendency that the mechanical strength in the direction perpendicular to the alignment direction tends to decrease significantly as the film approaches a complete uniaxial (uniaxially symmetric) film.

The NZ coefficient is represented by |Ny-Nz|/|Ny-Nx|), where Ny represents the refractive index in the direction of the slow axis, and Nx represents the refractive index in the direction perpendicular to the slow axis (refractive index in the direction of the fast axis), Nz represents the refractive index in the thickness direction. The alignment axis of the thin film was obtained using a molecular alignment meter (manufactured by Oji Scientific Instruments Co., Ltd., MOA-6004 type molecular alignment meter), and was obtained by an Abbe refractometer (manufactured by Atago Corporation, NAR-4T, measurement wavelength 589 nm). The biaxial refractive index (Ny, Nx, where Ny>Nx) in the direction of the alignment axis and the direction perpendicular thereto, and the refractive index (Nz) in the thickness direction. The value obtained by this operation can be substituted into |Ny-Nz|/|Ny-Nx| to obtain the NZ coefficient.

In addition, from the viewpoint of further suppressing rainbow-like stains, the Ny-Nx value of the polyester film is preferably 0.05 or more, more preferably 0.07 or more, still more preferably 0.08 or more, still more preferably 0.09 or more, Preferably, it is 0.1 or more. 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 the present invention, as a more preferable aspect, the refractive index of the polyester film in the direction parallel to the transmission axis direction of the polarizer constituting the polarizing plate is preferably within the range of 1.53 to 1.62. Thereby, reflection at the interface between the polarizer and the polyester film can be suppressed, and rainbow-like unevenness can be further suppressed. When the refractive index exceeds 1.62, rainbow-like unevenness may be generated when viewed from an oblique direction. The refractive index of the polyester film in a direction parallel to the transmission axis direction of the polarizer is preferably at most 1.61, more preferably at most 1.60, still more preferably at most 1.59, even more preferably at most 1.58.

On the other hand, the lower limit value of the refractive index of the polyester film in the direction parallel to the transmission axis direction of the polarizer is 1.53. When the refractive index is less than 1.53, crystallization of the polyester film becomes insufficient, and properties obtained by stretching, such as dimensional stability, mechanical strength, and chemical resistance, become insufficient, which is unfavorable. 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 conceivable.

In terms of setting the refractive index of the polyester film in a direction parallel to the transmission axis direction of the polarizer within the range of 1.53 to 1.62, the polarizer is preferably the transmission axis of the polarizer and the fast axis of the polyester film (compared with the fast axis of the polyester film). vertical to the slow axis) approximately parallel to each other. In the polyester film, 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 stretching in the film forming step described later. 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 to 1.62 by making the fast axis direction of the polyester film approximately parallel to the transmission axis direction of the polarizer. Here, the so-called approximately parallel means that the angle between the transmission axis of the polarizer and the fast axis of the polarizer protective film (polyester film) is -15°～15°, preferably -10°～10°, more preferably -5°～5°, more preferably -3°～3°, more preferably -2°～2°, and then More preferably -1° to 1°. In a preferred embodiment, roughly parallel means substantially parallel. Here, "substantially parallel" means that the transmission axis of the polarizer and the fast axis of the polyester film are parallel to the extent that unavoidable variations are allowed when bonding the polarizer and the protective film. 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 fast axis direction of the polyester film is preferably 1.53 to 1.62, and the transmission axis of the polarizer and the fast axis of the polyester film are laminated in such a manner that the fast axis of the polarizer can be parallel to the transmission axis of the polarizer. The refractive index of the polyester film in the direction is 1.53 or more and 1.62 or less.

The polarizer protective film comprising the above-mentioned polyester film can be used for polarizing plates on both the light incident side (light source side) and the light emitting side (visible side), but is preferably used at least on the light emitting side (visible side) Protective film for polarizing plates. For the polarizer disposed on the light-emitting side, the polarizer protective film comprising the above-mentioned polyester film can be disposed on the liquid crystal cell side with the polarizer as a starting point, or on the light-emitting side, or on both sides. Preferably, it is arranged at least on the light emitting side. In the polarizing plate arranged on the light incident side, the polarizer protective film including the above-mentioned polyester film may be arranged on the light incident side from the polarizer, may be arranged on the liquid crystal cell side, or may be arranged on both sides. , but a preferred aspect is to arrange at least on the incident light side. In addition, the polarizing plate disposed on the light incident side may use a polarizer protective film with low retardation such as a triacetate cellulose film instead of a polarizer protective film made of a polyester film.

The polyester used for the polyester film can use polyethylene terephthalate or polyethylene naphthalate, and may contain other copolymerization components. These resins are excellent in transparency as well as thermal and mechanical properties, and can easily control retardation by stretching. In particular, polyethylene terephthalate has a large birefringence inherently, and the refractive index in the direction of the fast axis (perpendicular to the slow axis) can be lowered by stretching the film, and even if the thickness of the film is thin, it can be easily A large amount of retardation is obtained, so it is the most suitable material.

In addition, the polyester film preferably has a light transmittance of 20% or less at a wavelength of 380 nm for the purpose of suppressing deterioration of optically functional dyes such as iodine dyes. The 380nm light transmittance is more preferably less than 15%, more preferably less than 10%, and most preferably less than 5%. If the aforementioned light transmittance is 20% or less, deterioration of the optically functional pigment due to ultraviolet rays can be suppressed. Also, when the transmittance is measured in a direction perpendicular to the plane of the film, it 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 desirable to appropriately adjust the type and concentration of the ultraviolet absorber and the thickness of the film. The ultraviolet absorber used in the present invention is a known substance. Examples of the ultraviolet absorber include organic ultraviolet absorbers and inorganic ultraviolet absorbers, and organic ultraviolet absorbers are preferred from the viewpoint of transparency. Examples of organic ultraviolet absorbers include: benzotriazole-based, benzophenone-based, cyclic imide ester-based, and combinations thereof, and there is no particular limitation as long as the absorbance is within the range specified in the present invention. limit. However, from the viewpoint of durability, benzotriazole-based and cyclic iminoester-based are particularly preferable. When two or more ultraviolet absorbers are used in combination, since ultraviolet rays of respective wavelengths can be absorbed simultaneously, the ultraviolet absorbing 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。然而，並不特別限定於它們。Examples of benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and acrylonitrile-based ultraviolet absorbers include: 2-[2'-hydroxyl-5'-(methacryloxy Methyl)phenyl]-2H-benzotriazole, 2-[2'-hydroxyl-5'-(methacryloxyethyl)phenyl]-2H-benzotriazole, 2-[2 '-Hydroxy-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'-tertiarybutyl-5'-methylphenyl)-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-benzotriazole -2-yl)phenol, etc. As the cyclic imido ester ultraviolet absorber, for example, 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 them.

In addition, 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, anticoagulation agents, Gelling agent, surfactant, etc. Moreover, in order to exhibit high transparency, it is also preferable that a polyester film does not contain particle|grains substantially. "Substantially not containing particles" means, for example, in the case of inorganic particles, when the inorganic elements are quantified by fluorescent X-ray analysis, it is 50 ppm or less, preferably 10 ppm or less, particularly preferably below the detection limit. content.

At least one surface of the polyester film of the polarizer protective film used in the present invention is preferably provided with an anti-reflection layer and/or a low-reflection layer. The surface reflectance of the antireflection layer used in the present invention is preferably 2.0% or less. If it exceeds 2.0%, it will become easy to recognize rainbow-like spots. The surface reflectance of the antireflection layer is more preferably at most 1.6%, still more 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, and is, for example, 0.01%. The best is 0% reflectance. The reflectance can be measured by any method. For example, the reflectance of light at a wavelength of 550 nm can be measured from the surface on the antireflection layer side using a spectrophotometer (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 plastic film (polyester film) becomes 1/4 of the light wavelength If the wavelength or its odd multiples are formed, the anti-reflection effect can be obtained. In addition, when the antireflection layer is multilayered, an antireflection effect can be obtained if two or more layers of low-refractive index layers and high-refractive index layers are alternately formed, and the thickness of each layer is appropriately controlled for lamination. In addition, if necessary, a hard coat layer can be laminated between the antireflection layers, and an antifouling layer can be formed on the hard coat layer.

In addition, as an antireflection layer, what utilizes a moth-eye structure is also mentioned. The moth-eye structure refers to a concavo-convex structure formed on the surface at a pitch smaller than the wavelength. This structure can change the sudden and discontinuous change in the refractive index at the boundary portion with air to a continuous and gradual change in the refractive index. Thus, light reflection on the surface of the film is reduced by forming a moth-eye structure on the surface. The formation of the antireflection layer using the moth-eye structure can be carried out by referring to, for example, JP-A-2001-517319.

As a method for forming an antireflection film, 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, and an antireflection coating liquid coated on the surface of a substrate and A wet coating method in which it is dried to form an antireflective layer, or a combined method in which both methods are used in combination. The composition of the antireflection layer and its formation method are not particularly limited as long as the above characteristics are satisfied.

Low reflection layers can use learners. For example, it can be formed by a method of laminating at least one metal or oxide thin film by vapor deposition or sputtering, or a method of coating one or more organic thin films. As the low-reflection layer, one coated with an organic film having a lower refractive index than a polyester film or a hard coat layer laminated on a polyester film can be preferably used. The surface reflectance of the low reflection layer is preferably less than 5%, more preferably less than 4%, more preferably less than 3%, and more preferably less than 2%. The lower limit is not particularly limited, but is preferably about 0.8% to 1.0%.

The antireflection layer and/or the low reflection layer can further provide an antiglare function. 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 be used. Especially preferred is the combination of a low reflection layer and an antiglare layer. As the anti-glare layer, a known anti-glare layer can be used. For example, from the viewpoint of suppressing the 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 a polyester film.

When providing an antireflection layer or a low reflection layer, it is preferable that the polyester film has an easy-adhesive layer on the surface. At this time, from the viewpoint of suppressing interference by reflected light, it is preferable to adjust the refractive index of the easily-adhesive layer to the vicinity of the geometric mean value of the 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 well-known method, for example, can adjust easily by making a binder resin contain titanium, germanium, or other metal species.

In order to improve the adhesiveness with a polarizer, corona treatment, coating treatment, flame treatment, etc. may be given to a polyester film.

In the present invention, in order to improve the adhesion with the polarizer, it is preferable to have at least one of polyester resin, polyurethane resin or polyacrylic resin as the main component on at least one side of the film of the present invention. Easy-to-adhesive layer of ingredients. Here, the "main component" refers to a component that is 50% by mass or more in the solid content constituting the easily-adhesive layer. The coating liquid for forming the easily-adhesive layer is preferably an aqueous coating liquid containing at least one of water-soluble or water-dispersible copolyester resins, acrylic resins, and polyurethane resins. Examples of these coating liquids include water-soluble coatings disclosed in Japanese Patent No. 3567927, Japanese Patent No. 3589232, Japanese Patent No. 3589233, Japanese Patent No. 3900191, and Japanese Patent No. 4150982. Sexual or water-dispersible copolyester resin solution, acrylic resin solution, polyurethane resin solution, etc.

The easy-adhesive layer can be obtained by applying the above-mentioned coating liquid to one or both surfaces of a uniaxially stretched film in the longitudinal direction, drying at 100 to 150° C., and stretching in the transverse direction. The coating amount of the final easily-adhesive layer is preferably managed to be 0.05 to 0.20 g/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 (Blocking Resistance) may decrease. When providing an easily-adhesive layer on both surfaces of a polyester film, the application|coating quantity of the easily-adhesive layer of both surfaces may be the same or different, and it can set each independently within the said range.

It is preferable to add particles to the easily-adhesive layer in order to impart slipperiness. It is preferable to use fine 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. As the particles contained in the easy-adhesive layer, for example, titanium oxide, barium sulfate, calcium carbonate, calcium sulfate, silica, alumina, talc, kaolin, clay, calcium phosphate, mica, hectorite, oxide Inorganic particles such as zirconium, 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 add in combination of 2 or more types.

In addition, as a method of applying the coating liquid, a known method can be used. For example, a reverse roll coating method, a gravure coating method, a kiss coating method, a roll brush method, a spray coating method, an air knife coating method, a wire bar coating method, a pipe doctor method, etc. can be mentioned. These methods are performed alone or in combination.

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

The polyester film used as a polarizer protective film can be manufactured according to the manufacturing method of a general polyester film. For example, the method of melting the polyester resin and extruding the non-oriented polyester extruded into a sheet is stretched in the longitudinal direction by using a speed difference of the rollers at a temperature higher than the glass transition temperature. The frame is stretched in the transverse direction and subjected to heat treatment.

The polyester film used in the present invention can be a uniaxially stretched film or a biaxially stretched film. When using a biaxially stretched film as a polarizer protective film, it should be noted that Iridescent stains are not visible when viewed directly above, but rainbow-shaped stains may be observed when viewed from an oblique direction.

When the film forming conditions of the polyester film are specifically described, the longitudinal stretching temperature and the transverse stretching temperature are preferably 80 to 130°C, particularly preferably 90 to 120°C. For aligning the film so that the slow axis is in the TD direction, the longitudinal stretch ratio is preferably 1.0 to 3.5 times, and particularly preferably 1.0 to 3.0 times. In addition, the lateral stretch ratio is preferably from 2.5 to 6.0 times, particularly preferably from 3.0 to 5.5 times. In terms of aligning the film so that the slow axis moves toward the MD direction, the longitudinal stretch ratio is preferably 2.5 to 6.0 times, particularly preferably 3.0 to 5.5 times. In addition, the lateral stretch ratio is preferably from 1.0 to 3.5 times, particularly preferably from 1.0 to 3.0 times. In order to control the refractive index or retardation in the fast axis direction of the polyester film within the above range, it is preferable to control the ratio of the longitudinal stretch ratio to the transverse stretch ratio. When the difference in the draw ratios in length and width is too small, the refractive index in the fast axis direction of the polyester film tends to exceed 1.62, and it becomes difficult to increase the retardation, which is not preferable. In addition, setting the stretching temperature low is a preferable countermeasure in terms of reducing the refractive index in the fast axis direction of the polyester film and increasing the retardation. In the subsequent 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 large 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 vertical stretch ratio is lowered in order to increase the retardation, the vertical thickness unevenness may become large. Since the thickness unevenness in the longitudinal direction has a very poor region within a specific range of the draw ratio, it is desirable to set the film forming conditions outside this range.

The thickness unevenness of the polyester film is preferably at most 5.0%, more preferably at most 4.5%, even more preferably at most 4.0%, and most preferably at most 3.0%.

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 draw ratio, the lower the stretching temperature, and the thicker the film, the easier it becomes to obtain a high retardation. Conversely, the smaller the draw ratio is, the higher the stretching temperature is, and the thinner the film is, the easier it is to obtain a low retardation. However, when the thickness of the film is increased, the retardation in the thickness direction tends to increase. Therefore, it is desirable that the film thickness is appropriately set within the range described later. In addition, in addition to the control of retardation, it is preferable to set the final film forming conditions in consideration of physical properties required for processing and the like.

The thickness of the polyester film is arbitrary, but is preferably in the range of 15 to 300 μm, more preferably in the range of 15 to 200 μm. Even a thin film with a thickness of less than 15 μm can theoretically obtain a retardation of 1500 nm or more. However, in this case, the anisotropy of the mechanical properties of the thin film becomes remarkable, and cracks, breakage, etc. tend to occur, and the practicality as an industrial material is significantly reduced. 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 polarizing plate becomes too thick, which is not preferable. From the viewpoint of practicality as a polarizer protective film, the upper limit of the thickness is preferably 200 μm. The upper limit of the particularly preferable thickness is 100 μm, which is about the same as that of a general TAC thin film. Even within the above thickness range, in order to control the amount of retardation within the range of the present invention, the polyester used as the film base material is suitably polyethylene terephthalate.

In addition, as a method of blending the ultraviolet absorber into the polyester film, a combination of known methods can be used. For example, the following method can be used to blend the dried ultraviolet absorber in advance using a kneading extruder. It is blended with the polymer raw material to make a master batch, and the predetermined master batch is mixed with the polymer raw material when the film is formed.

At this time, in order to uniformly disperse the ultraviolet absorber and blend it economically, the concentration of the ultraviolet absorber in the masterbatch is preferably set to a concentration of 5 to 30% by mass. As conditions for preparing the masterbatch, it is preferable to use a kneading extruder, extrude at a temperature of not less than the melting point of the polyester raw material and not more than 290° C., and extrude in 1 to 15 minutes. At 290° C. or higher, the loss of the ultraviolet absorber is significant, and the decrease in the viscosity of the masterbatch becomes large. When the extrusion time is 1 minute or less, uniform mixing of the ultraviolet absorber becomes difficult. At this time, a stabilizer, a color tone adjuster, and an antistatic agent may be added as necessary.

Moreover, it is preferable to make a polyester film into a multilayer structure of at least 3 layers, and to add an ultraviolet absorber to the middle layer of a film. A film with a three-layer structure including an ultraviolet absorber in the intermediate layer can be specifically produced as follows. For the outer layer, polyester pellets are fed alone to a known melt lamination extruder, and for the middle layer, a masterbatch containing an ultraviolet absorber and polyester pellets are mixed in a predetermined ratio and dried. It is supplied to a known extruder for fusion lamination, extruded into a sheet form from a slit-shaped die (die), cooled and solidified on a casting roll, and an unstretched film is produced. 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, and the A three-layer sheet was extruded and cooled with a casting roll to produce an unstretched film. In addition, it is preferable to perform high-precision filtration at the time of melt extrusion in order to remove foreign substances contained in the raw material polyester that cause optical defects. The filter particle size (initial filtration efficiency 95%) of the filter medium used for 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]

Hereinafter, the present invention will be described in more detail with reference to the examples, but the present invention is not limited by the following examples, and can also be implemented with appropriate changes within the scope that can meet the gist of the present invention, and those embodiments also include Within the technical scope of the present invention. In addition, the evaluation methods of the physical properties in the following examples are as follows. (1) Refractive index of polyester film

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

The amount of retardation refers to the parameter defined by the product (ΔNxy×d) of the anisotropy of the refractive index (ΔNxy=|Nx-Ny|) of the orthogonal biaxial axis on the film and the film thickness d (nm), expressing the optical The scale of isotropy and anisotropy. The biaxial refractive index anisotropy (ΔNxy) was obtained by the following method. The direction of the slow axis of the film was determined using a molecular alignment meter (Molecular Orientation Meter MOA-6004, manufactured by Oji Scientific Instruments Co., Ltd.), and a rectangle of 4 cm x 2 cm was cut out so that the direction of the slow axis became parallel to the long side of the sample for measurement. , as a sample for measurement. For this sample, using an Abbe refractometer (manufactured by Atago Corporation, NAR-4T, measurement wavelength 589nm), the refractive index of the orthogonal biaxial (refractive index in the slow axis direction: Ny, Ny, perpendicular to the slow axis direction) was obtained. The refractive index in the direction: Nx) and the refractive index in the thickness direction (Nz), let the absolute value (|Nx-Ny|) of the above-mentioned biaxial refractive index difference be the anisotropy of the refractive index (ΔNxy). The thickness d (nm) of the film was measured using an electric micrometer (manufactured by Feinpruf, Millitron 1245D), and the unit was converted into 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 direction retardation (Rth)

Retardation in the thickness direction refers to the indicated retardation obtained by multiplying the two birefringences ΔNxz (=|Nx-Nz|) and ΔNyz (=|Ny-Nz|) by the film thickness d when viewed from the cross-section in the thickness direction of the film The average parameter of . Nx, Ny, Nz and film thickness d (nm) were obtained by the same method as the measurement of retardation, and the average value of (ΔNxz×d) and (ΔNyz×d) was calculated to obtain thickness direction retardation (Rth). (4) NZ coefficient

The values of Ny, Nx, and Nz obtained in (1) above are substituted into NZ=|Ny-Nz|/|Ny-Nx| to obtain the value of the NZ coefficient. (5) Determination of the luminescence spectrum of the backlight source

The liquid crystal display device used in each example was REGZA 43J10X manufactured by Toshiba Corporation. When the emission spectrum of the backlight light source (white light-emitting diode) of this liquid crystal display device was measured using a multi-channel spectrometer PMA-12 manufactured by Hamamatsu Photonics, emission spectra having peaks around 450 nm, 535 nm, and 630 nm were observed. The full width at half maximum of each peak (the full width at half maximum of the peak having the highest peak intensity in each wavelength region) was 17 nm for the peak at 450 nm, 45 nm for the peak at 535 nm, and 2 nm for the peak at 630 nm. In addition, this light source has a plurality of peaks in the wavelength region of 600nm to 780nm, and the peak at around 630nm, which has the highest peak intensity in this region, was used to evaluate the full width at half maximum. 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). Also, on the side opposite to the side where the anti-reflection layer (or low-reflection layer) is provided on the polyester film, after blackening with a magic pen, stick a black vinyl tape (Kowa Vinyl Tape (stock), HF-737, Width 50mm) was measured. (7) Observation of rainbow spots

In a dark room, the liquid crystal display devices obtained in each Example were visually observed from the front and oblique directions, and the presence or absence of iridescent spots was judged as follows.

○: No rainbow spots observed △: A little rainbow spot is observed ×: Rainbow spot observed ××: Obvious rainbow spots were observed (Manufacturing example 1-polyester A)

When the temperature reaches 200°C, 86.4 parts by mass of terephthalic acid and 64.6 parts by mass of ethylene glycol are put into the reaction kettle for raising the temperature, and 0.017 parts by mass of antimony trioxide and 0.064 parts by mass of magnesium acetate tetrahydrate are added as catalysts while stirring. Parts, 0.16 parts by mass of triethylamine. Next, pressurization and temperature raising were carried out, and after pressurized esterification reaction was performed on the conditions of gauge pressure 0.34MPa and 240 degreeC, the esterification reactor 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, after 15 minutes, dispersion treatment was performed with a high-pressure disperser, and after 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reactor, and polycondensation reaction was performed at 280° C. under reduced pressure.

After the polycondensation reaction is completed, filter with a filter made of Naslon with a 95% cut-off diameter of 5 μm, extrude it into a strand from a nozzle, and use a pre-filtered filter (pore size: 1 μm or less) cooling water to cool, solidify, 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. (Hereafter abbreviated as PET(A).) (Manufacturing example 2-polyester B)

-4-酮)10質量份、不含有粒子的PET(A)(固有黏度為0.62dl/g) 90質量份混合，使用混練擠出機，得到含有紫外線吸收劑的聚對苯二甲酸乙二酯樹脂(B)。(以下簡記為PET(B)。) (製造例3-接著性改質塗布液的調整)The dried UV absorber (2,2'-(1,4-phenylene)bis(4H-3,1-benzo

-4-ketone) 10 parts by mass and 90 parts by mass of PET (A) (intrinsic viscosity: 0.62dl/g) not containing particles were mixed, and a polyethylene terephthalate containing an ultraviolet absorber was obtained by using a kneading extruder. Ester resin (B). (Hereafter abbreviated as PET (B).) (Manufacturing Example 3-Adjustment of Adhesive Modification Coating Liquid)

Utilize common method to carry out transesterification reaction and polycondensation reaction, prepare as dibasic acid component (relative to dibasic acid component whole) terephthalic acid 46 mol %, isophthalic acid 46 mol % and isophthalic acid- Water-dispersible sulfonic acid containing 8 mol% of sodium 5-sulfonate, 50 mol% of ethylene glycol and 50 mol% of neopentyl glycol as glycol components (relative to the entire glycol component) Metal salt based copolyester resin. Next, after mixing 51.4 parts by mass of water, 38 parts by mass of isopropanol, 5 parts by mass of n-butyl cellosolve, and 0.06 parts by mass of a nonionic surfactant, heat and stir, and once the temperature reaches 77°C, add the above-mentioned water-dispersible sulfonate-containing 5 parts by mass of acid metal salt-based copolyester resin, and continued stirring until no resin agglomeration, and then cooling the aqueous resin dispersion to room temperature to obtain a uniform water-dispersible copolyester resin solution with a solid content concentration of 5.0% by mass. Further, 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, 0.54 parts by mass of an aqueous dispersion of Sylysia 310 was added to 99.46 parts by mass of the above-mentioned water-dispersible copolyester resin liquid. 20 parts by mass of water was added while stirring to obtain an adhesive modification coating liquid. (Production Example 4 - Preparation of High Refractive Index Coating Agent)

Put 80 parts by mass of methyl methacrylate, 20 parts by mass of methacrylic acid, 1 part by mass of azoisobutyronitrile, and 200 parts by mass of isopropanol into a reaction container, and react at 80°C for 7 hours under a nitrogen atmosphere , Obtain the isopropanol solution of the polymer of weight average molecular weight 30000. Furthermore, the obtained polymer solution was diluted with isopropanol to 5 mass % of solid content, and the acrylic resin solution B was obtained. Next, the obtained acrylic resin solution B was mixed as follows to obtain a coating solution for forming a high refractive index layer.

‧Acrylic resin solution B 5 parts by mass ‧Bisphenol A diglycidyl ether 0.25 parts by mass ‧0.5 parts by mass of titanium oxide particles with an average particle size of 20nm ‧Triphenylphosphine 0.05 parts by mass ‧Isopropanol 14.25 parts by mass (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 put into a reaction container, and it was made to react at 80 degreeC under nitrogen atmosphere for 7 hours, and the methyl ethyl ketone solution of the polymer with a weight average molecular weight of 20000 was obtained. The obtained polymer solution was diluted with methyl ethyl ketone to a solid content concentration of 5% by mass to obtain a fluoropolymer solution C. The obtained fluoropolymer solution C was mixed as follows to obtain a coating solution for forming a low refractive index layer.

‧Fluoropolymer Solution C 44 parts by mass ‧1,10-bis(2,3-epoxypropoxy)-2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9- Hexadecafluorodecane (manufactured by Kyoeisha Chemical Co., Ltd., Fluorite FE-16) 1 part by mass ‧Triphenylphosphine 0.1 parts by mass ‧Methyl ethyl ketone 19 parts by mass (Manufacturing Example 6-Adjustment of Antiglare Layer Coating Agent-1)

Unsaturated double bond-containing acrylic copolymer CYCLOMERP ACA-Z250 (manufactured by Daicel Chemical Industry Co., Ltd.) (49 parts by mass), cellulose acetate propionate CAP482-20 (number average molecular weight 75000) (manufactured by Eastman Chemical Co., Ltd.) (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 parts by mass) , The solid content of Irgacure 184 (manufactured by BASF) (10 parts by mass) was adjusted to 35% by mass, and a mixed solvent of methyl ethyl ketone:1-butanol=3:1 was added to obtain a coating liquid for forming an antiglare layer. (Manufacturing Example 7-Adjustment of Antiglare Layer Coating Agent-2)

Unsaturated double bond-containing acrylic copolymer CYCLOMERP ACA-Z250 (manufactured by Daicel Chemical Industry Co., Ltd.) (49 parts by mass), cellulose acetate propionate CAP482-0.5 (number average molecular weight 25000) (manufactured by Eastman Chemical Co., Ltd.) (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 parts by mass) , The solid content of Irgacure 184 (manufactured by BASF) (10 parts by mass) was adjusted to 35% by mass, and a mixed solvent of methyl ethyl ketone:1-butanol=3:1 was added to obtain a coating liquid for forming an antiglare layer. (Manufacturing Example 8-Adjustment of Antiglare Layer Coating Agent-3)

Unsaturated double bond-containing acrylic copolymer CYCLOMERP ACA-Z250 (manufactured by Daicel Chemical Industry Co., Ltd.) (49 parts by mass), cellulose acetate propionate CAP482-0.2 (number average molecular weight 15000) (manufactured by Eastman Chemical Co., Ltd.) (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 parts by mass) , The solid content of Irgacure 184 (manufactured by BASF) (10 parts by mass) was adjusted to 35% by mass, and a mixed solvent of methyl ethyl ketone:1-butanol=3:1 was added to obtain a coating liquid for forming an antiglare layer. (Polarizer protective film 1)

90 parts by mass of PET (A) resin pellets not containing 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) After 6 hours, it was supplied to the extruder 2 (for the middle layer II layer). In addition, the PET (A) was dried by a common method and supplied to the extruder 1 (for the outer layer I layer and the outer layer III layer) at 285° C. Melt down. These two kinds of polymers are respectively filtered with stainless steel sintered filter media (nominal filtration precision 10μm particle 95% cut-off), laminated in two kinds of three-layer confluence blocks, extruded into sheets from the extrusion port, and then electrostatically applied casting method It was wound on a casting drum with a surface temperature of 30°C, cooled and solidified, and an unstretched film was produced. At this time, the discharge rate of each extruder was adjusted so that the thickness ratio of I layer, II layer, and III layer might become 10:80:10.

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

The unstretched film on which the coating layer was formed was led to a tenter stretching machine, and was led to a hot air zone at a temperature of 125°C while clamping the ends of the film with clips, and stretched 4.0 times in the width direction. Next, while maintaining the stretched width in the width direction, treat at a temperature of 225°C for 10 seconds, and further perform a 3.0% relaxation treatment in the width direction to obtain a uniaxially stretched film with a thickness of about 100 μm. PET film.

On one coated surface of the uniaxially stretched PET film, the coating liquid for forming a high refractive index layer obtained by the above method 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, the coating liquid for forming a low refractive index layer obtained by the above-mentioned method was applied, and dried at 150° C. for 2 minutes to form a low refractive index layer with a film thickness of 0.1 μm to obtain a laminated antireflection layer. Polarizer protective film1. (Polarizer protective film 2)

Except for changing the line speed to change the thickness of the unstretched film, the film was formed in the same manner as polarizer protective film 1 to obtain polarizer protective film 2 with an antireflection layer-laminated film thickness of about 80 μm. (Polarizer protective film 3)

Except for changing the line speed to change the thickness of the unstretched film, the film was formed in the same manner as polarizer protective film 1 to obtain polarizer protective film 3 with a film thickness of about 60 μm laminated with an antireflection layer. (Polarizer protective film 4)

Except for changing the line speed to change the thickness of the unstretched film, film formation was performed in the same manner as polarizer protective film 1 to obtain polarizer protective film 4 with an antireflection layer-laminated film thickness of about 40 μm. (Polarizer protective film 5)

Except that the antireflection layer was not provided, on one coating surface of the polarizer protective film produced by the same method as that of the polarizer protective film 2, the antiglare layer coating agent-1 was coated in a manner that the film thickness after curing became 8 μm, and Dry in an oven at 80°C-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 1 to obtain a polarizer protective film 5 . (Polarizer protective film 6)

An antiglare layer and an antireflection layer were laminated in the same manner as in polarizer protective film 5 on one coated surface of polarizer protective film prepared in the same manner as polarizer protective film 3, except that no antireflection layer was provided. Polarizer protective film6. (Polarizer protective film 7)

Except that the antireflection layer was not provided, on one coating surface of the polarizer protective film prepared by the same method as that of the polarizer protective film 4, the antiglare layer coating agent-2 was coated with a film thickness of 8 μm after curing, and Dry in an oven at 80°C-60 seconds. Thereafter, the laminated anti-glare layer was irradiated with ultraviolet rays at an irradiation dose of 300 mJ/cm ² using an ultraviolet irradiation device (Fusion UV Systems Japan, light source H bulb). Thereafter, an antireflection layer was laminated on the antiglare layer in the same manner as for the polarizer protective film 1 to obtain a polarizer protective film 7 . (Polarizer protective film 8)

Using heated rollers and infrared heaters, heat the unstretched film produced by the same method as polarizer protective film 1 to 105°C, and then stretch 3.3 degrees in the traveling direction with rollers having a peripheral speed difference. After doubling, it was stretched 4.0 times in the width direction by being guided to a hot air zone at a temperature of 130° C., and a polarizer protective film 8 with a film thickness of about 30 μm laminated with an antireflective layer was obtained in the same way as the polarizer protective film 1 . (Polarizer protective film 9)

A polarizer protective film 9 having a film thickness of about 100 μm was obtained by the same method as the polarizer protective film 1 except that no antireflection layer was provided. (Polarizer protective film 10)

A polarizer protective film was obtained by laminating an antiglare layer in the same manner as that of polarizer protective film 5 on one coated surface of the polarizer protective film produced in the same manner as polarizer protective film 8, except that the antireflection layer was not provided. 10 (without laminated anti-reflection layer). (Polarizer protective film 11)

Except that the antireflection layer was not provided, on one coating surface of the polarizer protective film produced by the same method as that of the polarizer protective film 1, the anti-glare layer coating agent-3 was coated with a film thickness of 8 μm after curing, and used Dry in an oven at 80°C-60 seconds. Afterwards, using an ultraviolet irradiation device (Fusion UV Systems Japan, light source H bulb), irradiated with ultraviolet rays with an irradiation dose of 300 mJ/cm ² to obtain a polarizer protective film 11 laminated with an anti-glare layer.

Using the polarizer protective films 1 to 11, a liquid crystal display device was fabricated as described below. (Example 1)

In such a way that the transmission axis of the polarizer and the fast axis of the film become perpendicular, a polarizer protective film 1 is attached on one side of the polarizer comprising PVA and iodine, and a TAC film (Fuji Film (stock) company) is attached on its opposite side. made, and the thickness is 80 μm) to make a polarizing plate 1 . Also, a polarizer was laminated on the surface of the polarizer protective film on which the antireflection layer was not laminated to form a polarizing plate. A liquid crystal display device was fabricated by substituting the polarizing plate on the viewing side of REGZA 43J10X manufactured by Toshiba Corporation with the above-mentioned polarizing plate 1 so that the polyester film was on the opposite side (farther away) from the liquid crystal cell. Moreover, the direction of the transmission axis of the polarizing plate 1 is replaced so that the direction of the transmission axis of the polarizing plate before replacement becomes the same. (Example 2)

In such a way that the transmission axis of the polarizer and the fast axis of the film become perpendicular, a polarizer protective film 2 is attached on one side of the polarizer comprising PVA and iodine, and a TAC film (Fuji Film (stock) company) is attached on its opposite side. made, with a thickness of 80 μm) to produce a polarizing plate 2 . Also, a polarizer was laminated on the surface of the polarizer protective film on which the antireflection layer was not laminated to form a polarizing plate. Except having changed the polarizing plate 1 into the polarizing plate 2, it carried out similarly to Example 1, and produced the liquid crystal display device. (Example 3)

In the mode that the transmission axis of the polarizer and the fast axis of the film become perpendicular, a polarizer protective film 3 is attached on one side of the polarizer comprising PVA and iodine, and a TAC film (Fuji Film (stock) company) is attached on its opposite side. made, with a thickness of 80 μm) to make a polarizing plate 3 . Also, a polarizer was laminated on the surface of the polarizer protective film on which the antireflection layer was not laminated to form a polarizing plate. Except having changed the polarizing plate 1 into the polarizing plate 3, it carried out similarly to Example 1, and produced the liquid crystal display device. (Example 4)

In the mode that the transmission axis of the polarizer and the fast axis of the film become perpendicular, a polarizer protective film 4 is attached on one side of the polarizer comprising PVA and iodine, and a TAC film (Fuji Film (stock) company) is attached on its opposite side. made, with a thickness of 80 μm) to make a polarizing plate 4 . Also, a polarizer was laminated on the surface of the polarizer protective film on which the antireflection layer was not laminated to form a polarizing plate. Except having changed the polarizing plate 1 into the polarizing plate 4, it carried out similarly to Example 1, and produced the liquid crystal display device. (Example 5)

With the transmission axis of the polarizer and the fast axis of the film becoming parallel, the polarizer protective film 4 is attached on one side of the polarizer comprising PVA and iodine, and the TAC film (Fuji Film (stock) company) is attached on its opposite side. made, with a thickness of 80 μm) to make a polarizing plate 5 . Also, a polarizer was laminated on the surface of the polarizer protective film on which the antireflection layer was not laminated to form a polarizing plate. Except having changed the polarizing plate 1 into the polarizing plate 5, it carried out similarly to Example 1, and produced the liquid crystal display device. (Example 6)

In such a way that the transmission axis of the polarizer and the fast axis of the film become perpendicular, a polarizer protective film 5 is attached on one side of the polarizer comprising PVA and iodine, and a TAC film (Fuji Film (stock) company) is attached on its opposite side. made, with a thickness of 80 μm) to make the polarizing plate 6 . In addition, a polarizer is laminated on the surface of the polarizer protective film on which the antireflection layer and the antiglare layer are not laminated to form a polarizing plate. Except having changed the polarizing plate 1 into the polarizing plate 6, it carried out similarly to Example 1, and produced the liquid crystal display device. (Example 7)

In such a way that the transmission axis of the polarizer and the fast axis of the film become perpendicular, a polarizer protective film 6 is attached on one side of the polarizer comprising PVA and iodine, and a TAC film (Fuji Film (stock) company) is attached on its opposite side. made, with a thickness of 80 μm) to make a polarizing plate 7 . In addition, a polarizer is laminated on the surface of the polarizer protective film on which the antireflection layer and the antiglare layer are not laminated to form a polarizing plate. Except having changed the polarizing plate 1 into the polarizing plate 7, it carried out similarly to Example 1, and produced the liquid crystal display device. (Embodiment 8)

With the transmission axis of the polarizer and the fast axis of the film becoming vertical mode, the polarizer protective film 7 is attached on one side of the polarizer comprising PVA and iodine, and the TAC film (Fuji Film (stock) company) is attached on its opposite side. made, with a thickness of 80 μm) to make a polarizing plate 8 . In addition, a polarizer is laminated on the surface of the polarizer protective film on which the antireflection layer and the antiglare layer are not laminated to form a polarizing plate. Except having changed the polarizing plate 1 into the polarizing plate 8, it carried out similarly to Example 1, and produced the liquid crystal display device. (comparative example 1)

In such a way that the transmission axis of the polarizer and the fast axis of the film become perpendicular, a polarizer protective film 8 is attached on one side of the polarizer comprising PVA and iodine, and a TAC film (Fuji Film (stock) company) is attached on its opposite side. made, with a thickness of 80 μm) to make a polarizing plate 9 . Also, a polarizer was laminated on the surface of the polarizer protective film on which the antireflection layer was not laminated to form a polarizing plate. A liquid crystal display device was fabricated by replacing the polarizing plate on the visible side of REGZA 43J10X manufactured by Toshiba Corporation with the above-mentioned polarizing plate 9 so that the polyester film was on the opposite side (farther away) from the liquid crystal cell. Moreover, the direction of the transmission axis of the polarizing plate 9 is replaced so that the direction of the transmission axis of the polarizing plate before replacement becomes the same. (comparative example 2)

In such a way that the transmission axis of the polarizer and the fast axis of the film become perpendicular, a polarizer protective film 9 is attached on one side of the polarizer comprising PVA and iodine, and a TAC film (Fuji Film (stock) company) is attached on its opposite side. made, and the thickness is 80 μm) to make the polarizing plate 10 . Except having changed the polarizing plate 9 into the polarizing plate 10, it carried out similarly to the comparative example 1, and produced the liquid crystal display device. (comparative example 3)

In such a way that the transmission axis of the polarizer and the fast axis of the film become perpendicular, a polarizer protective film 10 is attached on one side of the polarizer comprising PVA and iodine, and a TAC film (Fuji Film (stock) company) is attached on its opposite side. made, with a thickness of 80 μm) to make the polarizing plate 11 . Also, a polarizer was laminated on the surface of the polarizer protective film on which the anti-glare layer was not laminated to form a polarizing plate. Except having changed the polarizing plate 9 into the polarizing plate 11, it carried out similarly to the comparative example 1, and produced the liquid crystal display device. (comparative example 4)

In such a way that the transmission axis of the polarizer and the fast axis of the film become perpendicular, a polarizer protective film 11 is attached on one side of the polarizer comprising PVA and iodine, and a TAC film (Fuji Film (stock) company) is attached on its opposite side. made, with a thickness of 80 μm) to make the polarizing plate 12 . Also, a polarizer was laminated on the surface of the polarizer protective film on which the anti-glare layer was not laminated to form a polarizing plate. Except having changed the polarizing plate 9 into the polarizing plate 12, it carried out similarly to the comparative example 1, and produced the liquid crystal display device.

Table 1 below shows the results of measuring the iris observation of the liquid crystal display devices obtained in the respective examples.

Table 1 Polarizer protective film Thickness (μm) nx Ny Nz Re(nm) Rth(nm) NZ coefficient Re/Rth ratio Reflectivity(%) rainbow spot observation Example 1 Polarizer protective film 1 100 1.588 1.691 1.516 10300 12350 1.699 0.834 0.8 ○ Example 2 Polarizer protective film 2 80 1.589 1.690 1.515 8080 9960 1.733 0.811 0.8 ○ Example 3 Polarizer protective film 3 60 1.589 1.690 1.515 6060 7470 1.733 0.811 0.8 △ Example 4 Polarizer protective film 4 40 1.587 1.691 1.516 4160 4920 1.683 0.846 0.8 △ Example 5 Polarizer protective film 4 40 1.587 1.691 1.516 4160 4920 1.683 0.846 0.8 ○ Example 6 Polarizer protective film5 80 1.589 1.690 1.515 8080 9960 1.733 0.811 0.8 ○ Example 7 Polarizer protective film 6 60 1.589 1.690 1.515 6060 7470 1.733 0.811 0.8 ○ Example 8 Polarizer protective film 7 40 1.587 1.691 1.516 4160 4920 1.683 0.846 0.8 ○ Comparative example 1 Polarizer protective film8 30 1.640 1.688 1.597 1440 2010 1.896 0.716 0.8 x Comparative example 2 Polarizer protective film 9 100 1.588 1.691 1.516 10300 12350 1.699 0.834 5.0 ×× Comparative example 3 Polarizer protective film 10 30 1.640 1.688 1.597 1440 2010 1.896 0.716 5.0 x Comparative example 4 Polarizer protective film 11 100 1.588 1.691 1.516 10300 12350 1.699 0.834 5.0 x [Possibility of industrial use]

The liquid crystal display device and the polarizing plate of the present invention can ensure good visibility with effectively suppressed occurrence of rainbow-like stains at any angle, and make great contributions to the industry.

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Claims (18)

A liquid crystal display device has a backlight source, two polarizers, and a liquid crystal cell arranged between the two polarizers, the backlight source is a white light source, and the white light source includes a blue light-emitting diode and a fluoride fluorescent In the polarizer, at least one polarizer is laminated with a polyester film on at least one side of the polarizer, and the polyester film has a retardation of 1500 to 30000 nm, and an antireflection film is laminated on at least one side of the polyester film. layer and/or low reflection layer. The liquid crystal display device according to claim 1, wherein the fluoride phosphor is a Mn ⁴⁺ activated fluoride complex phosphor. The liquid crystal display device according to claim 1, wherein the fluoride phosphor is K ₂ SiF ₆ :Mn ⁴⁺ . A liquid crystal display device having a backlight light source, two polarizers, and a liquid crystal cell arranged between the two polarizers, the backlight light source having a thickness of more than 400nm and less than 495nm, more than 495nm and less than 600nm, and more than 600nm and less than 780nm Each wavelength region has a peak top of the luminescence spectrum, and the half-maximum width of the peak with the highest peak intensity in the wavelength region between 600nm and 780nm is less than 5nm. At least one of the polarizers is attached to the At least one side of the polarizer is laminated with a polyester film, the polyester film has a retardation of 6000~30000nm, and at least one side of the polyester film is laminated with an anti-reflection layer and/or low reflection Floor. The liquid crystal display device as claimed in claim 4, wherein the light emission spectrum of the backlight light source is above 400nm and less than 495nm in the wavelength region, and the half-maximum width of the peak with the highest peak intensity is 5nm or more, and the wavelength region between 495nm and less than 600nm The full width at half maximum of the peak with the highest peak intensity in , is 5 nm or more. The liquid crystal display device according to claim 4 or 5, wherein the lower limit value of the half maximum width of the peak with the highest peak intensity in the wavelength region of 600 nm to 780 nm is 1 nm or more. The liquid crystal display device according to claim 4 or 5, wherein the upper limit of the half-maximum width of the peak with the highest peak intensity in the wavelength region of 400nm or more and less than 495nm is 80nm or less, and the peak intensity in the wavelength region of 495nm or more and less than 600nm is the highest The upper limit of the full width at half maximum of the peak is 80 nm or less. The liquid crystal display device according to any one of claims 1 to 3, wherein the retardation of the polyester film is not less than 6000 nm and not more than 30000 nm. The liquid crystal display device according to any one of claims 1 to 5, wherein the retardation of the polyester film is not less than 8000 nm and not more than 30000 nm. The liquid crystal display device according to any one of claims 1 to 5, wherein the ratio (Re/Rth) of the retardation (Re) to the retardation (Rth) in the thickness direction of the polyester film is 0.6 to 2.0. Liquid crystal display device as in any one of request items 1 to 5 Set, wherein the polyester film is a polyethylene terephthalate film. The liquid crystal display device according to any one of claims 1 to 5, wherein the surface reflectance of the antireflection layer at a wavelength of 550 nm is 2.0% or less. The liquid crystal display device according to any one of claims 1 to 5, wherein there are other layers between the anti-reflection layer and/or low-reflection layer and the polyester film. The liquid crystal display device according to any one of claims 1 to 5, wherein an antiglare layer is provided between the antireflection layer and/or low reflection layer and the polyester film. The liquid crystal display device according to any one of claims 1 to 5, wherein a hard coat layer is provided between the anti-reflection layer and/or low-reflection layer and the polyester film. The liquid crystal display device according to any one of claims 1 to 5, wherein the surface of the polyester film on the side where the anti-reflection layer and/or low-reflection layer is provided has an easy-adhesive layer. The liquid crystal display device according to any one of claims 1 to 3, wherein the two polarizers are a polarizer on the visible side and a polarizer on the light source side, and at least the polarizer on the visible side is laminated with the polyester on at least one side of the polarizer In the case of a thin film, the polyester film has a retardation of 1500-30000 nm, and an anti-reflection layer and/or a low-reflection layer are laminated on at least one side of the polyester film. The liquid crystal display device as claimed in item 4 or 5, wherein The two polarizers are a polarizer on the visible side and a polarizer on the light source side. At least the polarizer on the visible side is laminated with the polyester film on at least one side of the polarizer. The polyester film has a retardation of 6000~30000nm. At least one side of the polyester film is laminated with an anti-reflection layer and/or a low-reflection layer.