KR20190131514A - LCD, polarizer and polarizer protective film - Google Patents

Abstract

This invention provides the liquid crystal display device, a polarizing plate, and a polarizer protective film which can suppress the generation | occurrence | production of a rainbow stain, even when diversification of the wavelength spectrum of the backlight light source by the wide color gamut of a liquid crystal display device, and thinning a polarizer protective film. It is one task. A polarizer protective film comprising a polyethylene terephthalate resin film, wherein the polyethylene terephthalate resin film is a polarizer protective film characterized by satisfying the following (1) to (2): (1) Polyethylene terephthalate resin The film has a retardation of 3000 to 30000 nm, and (2) the rigid amorphous fraction is 33 wt% or more.

Description

LCD, polarizer and polarizer protective film

This invention relates to a liquid crystal display device, a polarizing plate, and a polarizer protective film.

The polarizing plate used for a liquid crystal display (LCD) is a structure which inserted the polarizer which iodine was dyed into polyvinyl alcohol (PVA) etc. normally with two polarizer protective films, and a triacetyl cellulose (TAC) film is usually used as a polarizer protective film. It is used. In recent years, with the thinning of LCD, the thickness of a polarizing plate is required. For this reason, however, when the thickness of the TAC film used as a protective film is made thin, sufficient mechanical strength will not be obtained and the problem that moisture permeability will deteriorate arises. Moreover, although a TAC film is very expensive and a polyester film is proposed as an inexpensive substitute material (patent documents 1-3), there existed a problem that a rainbow color stain was observed.

When arranging the orientation polyester film which has birefringence on one side of a polarizer, the polarization state changes when the linearly polarized light radiate | emitted from a backlight unit or a polarizer passes through a polyester film. The transmitted light exhibits a distinctive interference color by retardation, which is the product of birefringence and thickness of the oriented polyester film. Therefore, when a discontinuous emission spectrum such as a cold cathode tube or a hot cathode tube is used as a light source, the transmitted light intensity varies depending on the wavelength, resulting in rainbow color spots (see the 15th micro-optical conference preview, 30-31). term).

As a means to solve the above problem, it is proposed to use a white light source having a continuous and broad emission spectrum such as a white light emitting diode as a backlight light source, and to use an oriented polyester film having a constant retardation as a polarizer protective film. There is (patent document 4). White light emitting diodes have a continuous and broad emission spectrum in the visible light region. Therefore, when focusing on the envelope shape of the interference color spectrum by the transmitted light which transmitted the birefringent body, by controlling the retardation of an oriented polyester film, it becomes possible to acquire the spectrum similar to the emission spectrum of a light source, and thereby rainbow unevenness. Made it possible to suppress.

Japanese Patent Application Laid-Open No. 2002-116320 Japanese Laid-Open Patent Publication No. 2004-219620 Japanese Patent Application Laid-Open No. 2004-205773 WO2011 / 162198 publication

As a backlight light source of a liquid crystal display device, the white light emitting diode (white LED) which consists of a light emitting element which combined the blue light emitting diode and the yttrium aluminum garnet type yellow fluorescent substance (YAG type yellow fluorescent substance) is conventionally used widely. This white light source has a broad spectrum in the visible light region and is excellent in light emission efficiency, and thus is widely used as a backlight light source. However, in the liquid crystal display device using this white LED as a backlight light source, only about 20% of the spectrum that the human eye can recognize can reproduce colors.

On the other hand, due to the recent increase in the gamut expansion request, the light emission spectrum of the white light source has light having a clear peak shape in each wavelength region of R (red), G (green), and B (blue). I) A liquid crystal display device corresponding to color gamut has been developed. For example, a white light source using quantum dot technology, a phosphor having a clear emission peak in the regions of R (red) and G (green) by excitation light, and a phosphor-type white LED light source using a blue LED, and a three-wavelength white A wide color gamut-compatible liquid crystal display device has been developed that uses various kinds of light sources, such as an LED light source, a fluoride phosphor having a composition formula of K ₂ SiF ₆ : Mn ⁴ + (also called "KSF"), and a white LED light source using a blue LED have. In the case of such a wide color gamut-compatible liquid crystal display device, it is possible to reproduce colors of 60% or more of the spectrum that the human eye can recognize.

All of these white light sources have a narrow half-width of the peak compared with the light source which consists of a white light emitting diode using the conventional YAG system yellow fluorescent substance, and made the polyethylene terephthalate-type resin film which has retardation into the polarizer which is a structural member of a polarizing plate. When used as a protective film, it turned out newly that a rainbow stain may generate | occur | produce depending on the kind of light source.

Moreover, the request of further thinning of a polarizer protective film becomes strong, and even in such a case, the polyethylene terephthalate-type resin film (polarizer protection) which can suppress the rainbow stain at the time of observing a display screen from the inclination direction more Film) is required.

That is, in the present invention, even when the polyethylene terephthalate-based resin film is used as a polarizer protective film that is a constituent member of the polarizing plate in the liquid crystal display device corresponding to the wide color gamut or when the film is thinned, generation of rainbow spots can be suppressed. It is a subject to provide a liquid crystal display device, a polarizing plate, and a polarizer protective film with improved visibility.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining, the inventors discovered that the said subject was solved by controlling a rigid amorphous fraction in addition to the polyethylene terephthalate-type resin film having a specific range of retardation.

The typical present invention is as follows.

Item 1.

Light polarizer protective film which consists of a polyethylene terephthalate resin film which satisfy | fills following (1) and (2):

(1) Retardation is 3000 nm or more and 30000 nm or less

(2) The rigid amorphous fraction represented by the following formula is 33 wt% or more.

(Rigid amorphous fraction (wt%)) = 100- (movable amorphous fraction (wt%))-(mass fraction crystallinity (wt%)).

Item 2.

The polarizer protective film according to item 1, wherein the polyethylene terephthalate resin film further satisfies the following (3):

(3) The orientation degree with respect to the film surface of the (100) plane measured by X-ray diffraction is 0.7 or less.

Clause 3.

The polarizing plate in which the polarizer protective film of Claim 1 or 2 was laminated | stacked on at least one surface of polarizer.

Item 4.

A liquid crystal display device having a backlight light source, two polarizing plates, and a liquid crystal cell disposed between the two polarizing plates, wherein at least one of the two polarizing plates is the polarizing plate according to item 3.

According to the present invention, even when a polyethylene terephthalate-based resin film is used as a polarizer protective film that is a constituent member of a polarizing plate in a liquid crystal display device corresponding to wide color gamut or when a thin film is formed, generation of rainbow spots can be suppressed and visibility is achieved. This improved liquid crystal display device, a polarizing plate, and a polarizer protective film can be provided.

１．Polarizer protective film

It is preferable that the polyethylene terephthalate-type resin film used for the polarizer protective film of this invention has retardation of 3000 nm or more and 30000 nm or less. When the retardation is less than 3000 nm, when used as a polarizer protective film, a strong interference color is exhibited when observed from the inclined direction, and good visibility cannot be secured. The lower limit of preferable retardation is 4000 nm, and a next preferable lower limit is 5000 nm.

On the other hand, the upper limit of the retardation is preferably 30000 nm. Even if a polyethylene terephthalate-based resin film having a higher retardation is used, further improvement in visibility can not be obtained substantially, the thickness of the film is also considerably thick, and handleability as an industrial material is lowered. A preferable upper limit is 10000 nm, a more preferable upper limit is 9000 nm, and a still more preferable upper limit is 8000 nm.

The retardation may be obtained by measuring the refractive index and the film thickness in the biaxial direction in the film plane, or may be obtained using a commercially available automatic birefringence measuring device such as KOBRA-21ADH (Oji Keisoku Instruments Co., Ltd.). . The measurement wavelength of the refractive index is measured at 589 nm.

The refractive index difference in the film surface of the polyethylene terephthalate-based resin film (refractive index in the refractive index in the ground-axis direction) is preferably 0.08 or more, and more preferably 0.09 As mentioned above, More preferably, it is 0.10 or more. As for the upper limit of the said refractive index difference, 0.15 or less are preferable. It is preferable to extend | stretch strongly in one direction and to have a larger refractive index difference in a film plane from a viewpoint of suppressing rainbow spots more. In addition, the refractive index of a slow axis direction, and the refractive index of a fast axis direction can be calculated | required with an Abbe refractometer (Atago Co., NAR-4T, measurement wavelength 589 nm).

In addition to having the retardation of a specific range, the polyethylene terephthalate-type resin film used for the polarizer protective film of this invention is preferable that a rigid amorphous fraction is 33 wt% or more from a viewpoint of suppressing the rainbow spot observed from a diagonal direction. The rigid amorphous fraction of the polyethylene terephthalate resin film is preferably 33 wt% or more, more preferably 34 wt% or more, more preferably 35 wt% or more, and even more preferably 36 wt% or more. Although 60 wt% is preferable for an upper limit, about 50 wt% or about 45 wt% is enough. Here, the rigid amorphous fraction is represented by the following formula (1).

(Rigid amorphous fraction (wt%)) = 100- (movable amorphous fraction (wt%))-(mass fraction crystallinity (wt%)). (One)

In addition, in this specification, wt% is synonymous with mass%.

Conventionally, it has been thought that the higher-order structure of a polymer is divided into crystal and amorphous. However, in recent years, the amorphous region can be further distinguished by the temperature dependence of its molecular motion, and it is divided into a movable amorphous in which molecular motion is released at the glass transition point (Tg) and a rigid amorphous in which molecular motion is frozen even at a temperature above Tg. Reported. In the case of polyethylene terephthalate, this rigid amorphous is known to remain amorphous until the temperature of 200 degreeC vicinity. Therefore, it is thought that the crystallization accompanying extending | stretching and heat processing of a film is hard to progress, so that the rigid amorphous fraction is large. In the polyethylene terephthalate resin film, when the thickness and retardation are the same, the rainbow spots observed from the inclined direction are suppressed when the benzene ring is randomly oriented around the molecular chain axis, when used for the polarizer protective film. On the other hand, in a polyethylene terephthalate resin film, it is known that a benzene ring orientates in parallel with a film surface with crystallization. In the polyethylene terephthalate-based resin film formed by the conventional method, when the refractive index difference in the film surface described above is increased, the degree of orientation of the benzene ring to the film surface is also increased at the same time, and a sufficient rainbow stain suppression effect may not be obtained. there was. As the present inventors have studied, by controlling the rigid amorphous fraction in the above range, even when the refractive index difference in the film plane is increased, the orientation of the benzene ring accompanying crystallization is effectively suppressed, and the rainbow spot observed from the oblique direction can be suppressed. Found that.

In the above formula (1), the rigid amorphous fraction is indirectly obtained using the values of the movable amorphous fraction and the mass fraction crystallinity. The movable amorphous fraction is determined from the reversible heat capacity difference ΔCp in Tg of the reversible heat capacity curve obtained by the temperature modulated DSC measurement using a differential scanning calorimeter (manufactured by TA Instrument, Q100). In addition, a mass fraction crystallinity is computed by the value of the density obtained using the density gradient tube according to JISK7112. Details will be described later in the Examples.

The orientation degree with respect to the film surface of the benzene ring in a polyethylene terephthalate type resin film can be evaluated using the orientation degree with respect to the film surface of the (100) surface substantially parallel to a benzene ring as an index. In addition to having the retardation of a specific range, the polyethylene terephthalate-type resin film used for the polarizer protective film of this invention observes that the orientation degree with respect to the film surface of the (100) plane measured by X-ray diffraction is 0.7 or less from a diagonal direction. It is preferable from a viewpoint of suppressing the rainbow stain which becomes. 0.7 or less is preferable, as for the orientation degree with respect to the film surface of the (100) surface of a polyethylene terephthalate system resin film, More preferably, it is 0.68 or less, More preferably, it is 0.66 or less, More preferably, it is 0.64 or less. As for a minimum, 0.40 is preferable. The degree of orientation of the (100) plane with respect to the film plane is an index indicating the orientation around the molecular chain axis of the crystal of polyethylene terephthalate, and the lower this value, the more random the orientation around the molecular chain axis is. The more random the orientation around this molecular chain axis is, the more the rainbow spots observed from the oblique direction are suppressed.

In the X-ray diffraction measurement of the polymer, the intensity of X-rays scattered mainly by crystals is measured, but the intensity of X-rays scattered by amorphous (orientation amorphous) that is aligned and has regularity is also included in the measured value. Generally, the (100) plane refers to a specific crystal plane in the crystal lattice, but the orientation degree to the film plane of the (100) plane corresponds to an index of the orientation degree to the film plane of the benzene ring in crystals and orientation amorphous. .

As the degree of orientation of the (100) plane with respect to the film plane, an X-ray diffraction apparatus (RINT2100PC, manufactured by Rigaku Co., Ltd.) was used, and a half width of the diffraction intensity profile of the (100) plane obtained by wide-angle X-ray diffraction measurement was used. In addition, it is a parameter defined by the following formula. Details will be described later in the Examples.

Orientation degree with respect to the film surface of the (100) plane = (180-half-width) / 180

The polyethylene terephthalate resin film which is a protective film of this invention can be manufactured using the manufacturing method of a general polyester film. For example, a polyethylene terephthalate resin is melted, and the non-oriented polyethylene terephthalate resin extruded into a sheet is stretched in the longitudinal direction using a speed difference between rolls at a temperature equal to or higher than the glass transition temperature. Then, the method of extending | stretching to a horizontal direction with a tenter and performing heat processing is mentioned.

When the film forming conditions of a polyethylene terephthalate-type resin film are demonstrated concretely, 100-130 degreeC of longitudinal stretch temperature and lateral stretch temperature are preferable, Especially preferably, it is 110-125 degreeC.

When manufacturing the film which has a slow axis in a film width direction (TD direction), 0.7-1.5 times are preferable, and especially preferably, it is 0.7 times-1.0 time. Moreover, it is preferable to make transverse draw ratio high from a viewpoint of suppressing relaxation of the amorphous molecular chain in extending | stretching, and increasing a rigid amorphous fraction. The lower limit of the transverse stretching ratio is preferably 4.5 times, more preferably 4.7 times, and particularly preferably 5.0 times. On the other hand, when a lateral stretch magnification exceeds 7.0 times, a film will be easy to tear in a horizontal direction, and productivity will fall. Therefore, the upper limit of the transverse stretching ratio is preferably 7.0 times, more preferably 6.5 times, particularly preferably 6.0 times, and most preferably 5.5 times.

On the other hand, when manufacturing the film which has a slow axis in a film longitudinal direction (MD direction), horizontal draw ratio becomes like this. Preferably it is 1.0-3.0 times, More preferably, it is 2.0-3.0 times. From the viewpoint of suppressing relaxation of the amorphous molecular chain in the stretching and increasing the rigid amorphous fraction, the longitudinal stretching ratio is preferably high. The lower limit of the vertical draw ratio is preferably 4.5 times, more preferably 4.7 times, and particularly preferably 5.0 times. When the vertical draw ratio exceeds 7.0 times, the film tends to tear in the vertical direction and the productivity decreases, so the upper limit of the vertical draw ratio is preferably 7.0 times, more preferably 6.5 times, and particularly preferably 6.0 times. .

In order to control retardation to the said range, it is preferable to control the ratio of longitudinal stretch magnification and lateral stretch magnification, extending | stretching temperature, and thickness of a film. If the difference in stretching ratio between the length and width is too small, it is difficult to increase the retardation, which is not preferable.

In order to suppress the orientation to the film surface of the benzene ring accompanying crystallization at the time of heat processing, it is preferable to increase a rigid amorphous fraction. It is preferable to suppress relaxation of the amorphous molecular chain in extending | stretching specifically, and to enlarge the distortion rate in extending | stretching to the slow axis direction of a film. The distortion rate is preferably 13% / sec or more, more preferably 15% / sec or more, particularly preferably 17% / sec or more. From the viewpoint of film forming property, the upper limit of the distortion rate is preferably 60% / sec. Here, the distortion speed is an amount expressed by (nominal distortion (%) in stretching in the ground axis direction) / (time required (sec) in stretching in the ground axis direction)), and nominal distortion (%) Is calculated by ((strain amount (mm)) / (initial length (mm))) × 100.

In the subsequent heat treatment, the lower limit of the heat treatment temperature is preferably 150 ° C, more preferably 160 ° C, particularly preferably 170 ° C, most preferably 180 ° C from the viewpoint of promoting orientation crystallization and increasing the retardation. . On the other hand, the upper limit of the heat treatment temperature is preferably 220 ° C, more preferably 210 ° C, particularly preferably 200 from the viewpoint of preventing crystallization of the rigid amorphous and lowering the degree of orientation of the crystal (100) plane with respect to the film plane. ℃.

As for the polyethylene terephthalate resin which comprises a polyethylene terephthalate resin film, it is preferable that 85 mol% or more of a monomer unit is ethylene terephthalate. 90 mol% or more is preferable, and, as for the ethylene terephthalate unit, 95 mol% or more is more preferable. Moreover, as a copolymerization component, you may contain a well-known acid component and a glycol component. As polyethylene terephthalate resin, especially preferable is polyethylene terephthalate which is a homopolymer.

While these resins are excellent in transparency, they are also excellent in thermal and mechanical properties, and can easily control the retardation by stretching. Polyethylene terephthalate has a large intrinsic birefringence and can obtain a large retardation relatively easily even if the film thickness is thin, and is the most suitable material.

Moreover, for the purpose of suppressing deterioration of optical functional dyes, such as an iodine pigment | dye, it is preferable that the protective film of this invention is 20% or less in light transmittance of wavelength 380nm. 15% or less is more preferable, as for the light transmittance of 380 nm, 10% or less is more preferable, 5% or less is especially preferable. If the said light transmittance is 20% or less, alteration by the ultraviolet-ray of an optical functional pigment | dye can be suppressed. In addition, the transmittance | permeability in this invention is measured in the perpendicular direction with respect to the plane of a film, and can be measured using a spectrophotometer (for example, the Hitachi U-3500 type).

In order to make the transmittance | permeability of wavelength 380nm of the protective film of this invention into 20% or less, it is preferable to adjust suitably the kind, density | concentration, and thickness of a film of an ultraviolet absorber. The ultraviolet absorber used in the present invention is a known material. Although an organic type ultraviolet absorber and an inorganic type ultraviolet absorber are mentioned as a ultraviolet absorber, organic type ultraviolet absorber is preferable from a transparency viewpoint. Examples of the organic ultraviolet absorber include a benzotriazole type, a benzophenone type, a cyclic imino ester type, and combinations thereof, but are not particularly limited as long as they are within the absorbance range specified by the present invention. However, the benzotriazole type and the cyclic imino ester type are especially preferable from a viewpoint of durability. When two or more types of ultraviolet absorbers are used in combination, the ultraviolet rays of the respective wavelengths can be absorbed at the same time, so that the ultraviolet absorbing effect can be more improved.

As a benzophenone type ultraviolet absorber, a benzotriazole type ultraviolet absorber, and an acrylonitrile type ultraviolet absorber, for example, 2- [2'-hydroxy-5 '-(methacryloyloxymethyl) phenyl] -2H-benzo Triazole, 2- [2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl] -2H-benzotriazole, 2- [2'-hydroxy-5'-(methacryloyloxy Propyl) phenyl] -2H-benzotriazole, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 2,4- Di-tert-butyl-6- (5-chlorobenzotriazol-2-yl) phenol, 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole , 2- (5-chloro (2H) -benzotriazol-2-yl) -4-methyl-6- (tert-butyl) phenol, 2,2'-methylenebis (4- (1,1,3, 3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol etc. As a cyclic imino ester type ultraviolet absorber, it is 2,2 '-(1,4-, for example). Phenylene) bis (4H-3,1-benzooxazin-4-one), 2-methyl-3,1-benzooxa Zin-4-one, 2-butyl-3,1-benzooxazin-4-one, 2-phenyl-3,1-benzooxazin-4-one, and the like. no.

Moreover, it is also a preferable aspect to contain various additives other than a catalyst in the range which does not inhibit the effect of this invention other than a ultraviolet absorber. Examples of the additives include inorganic particles, heat resistant polymer particles, alkali metal compounds, alkaline earth metal compounds, phosphorus compounds, antistatic agents, light resistant agents, flame retardants, heat stabilizers, antioxidants, antigelling agents, surfactants, and the like. . Moreover, in order to show high transparency, it is also preferable that a polyethylene terephthalate type resin film does not contain particle | grains substantially. The term "substantially free of particles" means, for example, in the case of inorganic particles, a content of 50 ppm or less, preferably 10 ppm or less, particularly preferably below the detection limit when the inorganic element is quantified by fluorescence X-ray analysis. Means.

Moreover, as a method of mix | blending a ultraviolet absorber with the polyethylene terephthalate-type resin film in this invention, a well-known method can be combined and employ | adopted, For example, the ultraviolet absorber and the polymer raw material dried previously using the kneading extruder are used. And a master batch are produced, and it can mix | blend with the method etc. which mix this predetermined | prescribed masterbatch and a polymer raw material at the time of film forming.

At this time, it is preferable to make the ultraviolet absorber concentration of a masterbatch into the density | concentration of 5-30 mass% in order to disperse | distribute a ultraviolet absorber uniformly and to economically mix | blend. It is preferable to use a kneading extruder as conditions for producing a masterbatch, and to extrude 1-15 minutes at extrusion temperatures more than melting | fusing point of a polyethylene terephthalate-type raw material, and the temperature of 290 degreeC or less. At 290 degreeC or more, the weight loss of a ultraviolet absorber is large and the viscosity fall of a masterbatch becomes large. In 1 minute or less of extrusion time, uniform mixing of a ultraviolet absorber will become difficult. At this time, you may add a stabilizer, a color tone adjuster, and an antistatic agent as needed.

Moreover, in this invention, it is preferable to make a film into a multilayered structure of at least 3 layers or more, and to add a ultraviolet absorber to the intermediate | middle layer of a film. The film of the three-layer structure which contains a ultraviolet absorber in an intermediate | middle layer can be specifically produced as follows. The pellets of polyethylene terephthalate resin alone for the outer layer and the master batch containing the ultraviolet absorber for the intermediate layer and the pellets of the polyethylene terephthalate resin are mixed at a predetermined ratio, dried, and then supplied to a known melt laminating extruder. The sheet is extruded from the slit die into a sheet, and cooled and solidified on a casting roll to form an unstretched film. That is, using the two or more extruders, three layers of manifolds or a confluence block (for example, confluence block which has a rectangular confluence part), the film layer which comprises an outer layer and the film layer which comprises an intermediate layer are laminated | stacked. Then, three layers of sheets are extruded from the mold and cooled in a casting roll to form an unstretched film. Moreover, in this invention, in order to remove the foreign material contained in the polyethylene terephthalate-type resin of a raw material which causes an optical defect, it is preferable to perform high precision filtration at the time of melt extrusion. As for the filter particle size (95% of initial stage filtration efficiency) of the filter medium used for high precision filtration of molten resin, 15 micrometers or less are preferable. If the filter particle size of a media exceeds 15 micrometers, the removal of a foreign material of 20 micrometers or more will become inadequate easily.

In addition, the polyethylene terephthalate-based resin film of the present invention may be subjected to corona treatment, coating treatment, flame treatment or the like in order to improve adhesion to the polarizer.

In this invention, in order to improve adhesiveness with a polarizer, the easily bonding layer which has at least 1 sort (s) of a polyester resin, a polyurethane resin, or a polyacrylic resin on at least one side | surface of the film of this invention is a main component. It is preferable to have. Here, a "main component" means the component which is 50 mass% or more in the solid component which comprises an easily bonding layer. As for the coating liquid used for formation of the easily bonding layer of this invention, the aqueous coating liquid containing at least 1 sort (s) among water-soluble or water-dispersible co-polyester resin, an acrylic resin, and a polyurethane resin is preferable. As such a coating liquid, For example, Unexamined-Japanese-Patent No.3567927, Unexamined-Japanese-Patent No. 3589232, Unexamined-Japanese-Patent No.3589233, Unexamined-Japanese-Patent No. 3900191, Unexamined-Japanese-Patent No. 4150982, etc. are mentioned, for example. The disclosed water soluble or water dispersible copolyester resin solution, acrylic resin solution, polyurethane resin solution, and the like.

An easily bonding layer can apply | coat the said coating liquid to the single side | surface or both surfaces of the uniaxial stretched film of a longitudinal direction, and then it can dry at 100-150 degreeC, and can extend | stretch to a horizontal direction and can obtain it. It is preferable to manage the application amount of a final easily bonding layer at 0.05-0.2 g / m <2>. If the coating amount is significantly less than 0.05 g / m 2, the adhesiveness with the polarizer obtained may be insufficient. On the other hand, when application amount remarkably exceeds 0.2 g / m <2>, blocking resistance may fall. When providing an easily bonding layer on both surfaces of a polyethylene terephthalate resin film, the application amount of the easily bonding layer of both surfaces may be same or different, and can be set independently within the said range, respectively.

It is preferable to add particle | grains to an easily bonding layer, in order to provide diactivation. As for the average particle diameter of microparticles | fine-particles, it is preferable to use the particle | grains of 2 micrometers or less. When the average particle diameter of particle | grains exceeds 2 micrometers remarkably, particle | grains will fall easily from a coating layer. Examples of the particles to be included in the adhesive layer include titanium oxide, barium sulfate, calcium carbonate, calcium sulfate, silica, alumina, talc, kaolin, clay, calcium phosphate, mica, hectorite, zirconia, tungsten oxide, and lithium fluoride. And inorganic particles such as calcium fluoride, and organic polymer particles such as styrene, acrylic, melamine, benzoguanamine, and silicone. These may be added to an easily bonding layer independently and can also be added in combination of 2 or more type.

Moreover, a well-known method can be used as a method of apply | coating a coating liquid. 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, and the like can be cited. It can carry out in combination.

In addition, the measurement of the average particle diameter of said particle | grains is performed by the following method. Take a picture of the particles with a scanning electron microscope (SEM), measure the maximum diameter (distance between the two points apart) of 300 to 500 particles at the same magnification such that the size of the smallest particle is 2 to 5 mm. Let the average value be the average particle diameter.

Although the thickness of the polyethylene terephthalate resin film of this invention is arbitrary, the range of 30-300 micrometers is preferable, More preferably, it is the range of 40-200 micrometers. Even with a film having a thickness of less than 30 μm, in principle, it is possible to obtain a retardation of 3000 nm or more. However, in that case, the anisotropy of the mechanical properties of the film becomes remarkable, tearing, cracking, etc. tend to occur, and the practicality as an industrial material falls remarkably. The minimum of especially preferable thickness is 45 micrometers. On the other hand, when the upper limit of the thickness of a polarizer protective film exceeds 300 micrometers, the thickness of a polarizing plate will become too thick and it is unpreferable. From the viewpoint of practicality as a polarizer protective film, the upper limit of the thickness is preferably 120 µm, more preferably 100 µm or less, even more preferably 80 µm or less, even more preferably 65 µm or less, even more preferably 60 Μm or less, even more preferably 55 µm or less. In general, from the viewpoint of thinning, the thickness of the polarizer protective film is preferably in the range of 30 to 65 µm.

In order to suppress the variation of retardation, it is preferable that the thickness variation of a film is small. Since extending | stretching temperature and a draw ratio have a big influence on the thickness variation of a film, it is necessary to optimize film forming conditions also from a viewpoint of thickness variation. In particular, when the vertical draw ratio is lowered to increase the retardation, the vertical thickness variation may worsen. Since there exists an area | region which becomes very bad in any specific range of a draw ratio in a vertical thickness deviation, it is preferable to set film forming conditions in the place except this range.

It is preferable that the thickness variation of the film of this invention is 5.0% or less, It is more preferable that it is 4.5% or less, It is further more preferable that it is 4.0% or less, It is especially preferable that it is 3.0% or less.

In the polyethylene terephthalate resin film used for the polarizer protective film, the Nz coefficient represented by | ny-nz | / | ny-nx | is preferably 1.7 or less. Nz coefficient can be calculated | required as follows. The orientation axis direction of a film is calculated | required using a molecular orientation system (Oji Keisuku Instruments Co., Ltd. make, MOA-6004 type molecular orientation system), and the biaxial refractive index (ny, nx, of an orientation axis direction and the direction orthogonal to this) is obtained. However, ny> nx) and the refractive index nz of the thickness direction are calculated | required with an Abbe refractometer (the Atago company make, NAR-4T, measurement wavelength 589nm). The Nz coefficients can be obtained by substituting nx, ny, and nz obtained in this way into an equation represented by | ny-nz | / | ny-nx |. Nz coefficient is more preferably 1.65 or less, still more preferably 1.63 or less. The lower limit of the Nz coefficient is 1.2. In addition, in order to maintain the mechanical strength of the film, the lower limit of the Nz coefficient is preferably 1.3 or more, more preferably 1.4 or more, and still more preferably 1.45 or more.

As for the polyethylene terephthalate resin film, the ratio (Re / Rth) of the retardation (Re) and thickness direction retardation (Rth) becomes like this. Preferably it is 0.2 or more, More preferably, it is 0.5 or more, More preferably, it is 0.6 or more to be. It is more preferable that the said ratio (Re / Rth) is large. 2.0 or less are preferable and, as for an upper limit, 1.8 or less are more preferable. In addition, with thickness direction retardation, the retardation obtained by multiplying two birefringence (DELTA) Nxz (= | nx-nz |) and (DELTA) Nyz (= | ny-nz |) by the film thickness d, respectively, when seen from the film thickness direction cross section, This parameter represents the average of. Thickness direction retardation (Rth) can be calculated | required by calculating | requiring nx, ny, nz, and film thickness d (nm), calculating the average value of ((DELTA) Nxzxd) and (DELTA) Nyzxd. In addition, nx, ny, and nz are calculated | required with an Abbe refractometer (the Atago company make, NAR-4T, measurement wavelength 589 nm).

２．Polarizing plate

The polarizing plate of the present invention has a structure in which a polarizer protective film is pasted onto at least one surface of a polarizer in which iodine is dyed in polyvinyl alcohol (PVA) or the like, and it is one of the polarizer protective films of the present invention. desirable. As another polarizer protective film, it is preferable to use the film without birefringence like typified by a TAC film, an acrylic film, and a norbornene-type film. Moreover, the other polarizer protective film does not necessarily need to exist. It is also a preferable aspect to apply | coat various hard coats to the surface for the purpose of anti-glare, glare suppression, flaw suppression, etc. to the polarizing plate used for this invention.

３．Liquid crystal display device

Generally, a liquid crystal panel consists of a back module, a liquid crystal cell, and a front module in the order which goes to the side (viewing side) which displays an image from the side which opposes a backlight light source. The rear module and the front module are generally composed of a transparent substrate, a transparent conductive film formed on the liquid crystal cell side surface thereof, and a polarizing plate disposed on the opposite side thereof. Here, the polarizing plate is disposed on the side opposite to the backlight light source in the rear module, and is disposed on the side (viewing side) displaying an image in the front module.

In the liquid crystal display device of the present invention, at least, the liquid crystal cell disposed between the backlight light source and the two polarizing plates is a constituent member. Moreover, you may have other structures other than these, for example, a color filter, a lens film, a diffusion sheet, an antireflection film, etc. suitably. It is preferable that at least one polarizing plate is the polarizing plate of this invention mentioned above among the said two polarizing plates.

As a structure of a backlight, the edge light system which uses a light guide plate, a reflecting plate, etc. as a structural member, or a direct type system may be sufficient.

Although it does not specifically limit as a backlight light source of a liquid crystal display device, The white LED of fluorescent substance system is preferable. That is, the device emits white light by combining a light emitting diode emitting blue light or ultraviolet light using a compound semiconductor and a phosphor. Examples of the phosphor include a yellow phosphor of yttrium aluminum garnet and a yellow phosphor of terbium aluminum garnet.

Moreover, as a backlight light source, the white light source which has the peak top of an emission spectrum in each wavelength region of 400 nm or more and less than 495 nm, 495 nm or more and less than 600 nm, and 600 nm or more and 780 nm or less is also preferable. For example, a white light source using quantum dot technology, a phosphor having an emission peak in the regions of R (red) and G (green) by excitation light, and a white LED light source of a phosphor type using a blue LED, and a white of 3 wavelength type LED light source, a combination of a red laser white LED light source, and other, for example, the composition formula is K ₂ SiF _6: and the like Mn ⁴ + a fluoride phosphor (also referred to as "KSF") as a white LED light source using a blue LED have. These are attracting attention as a backlight light source of the liquid crystal display device corresponding to a wide color gamut.

Although arrangement | positioning in the liquid crystal display device of the polarizer protective film of this invention which has the said specific retardation is not specifically limited, On the polarizing plate arrange | positioned at the incident light side (light source side), a liquid crystal cell, and an exit light side (viewing side) In the case of the liquid crystal display device in which the polarizing plates are arranged, the polarizer protective film on the incident light side of the polarizing plate disposed on the incident light side and / or the polarizer protective film on the outgoing light side of the polarizing plate arranged on the outgoing light side has the specific retardation. It is preferable that it is a polarizer protective film which consists of a terephthalate type resin film. An especially preferable aspect is an aspect which uses the polarizer protective film of the light exit side of the polarizing plate arrange | positioned at the light exit side as the polyethylene terephthalate-type resin film which has the said specific retardation. When arrange | positioning a polyethylene terephthalate-type resin film in the position of that excepting the above, the polarization characteristic of a liquid crystal cell may be changed. Since it is not preferable to use the polymer film of this invention in the place where polarization characteristic is needed, it is preferable to be used as a protective film of the polarizing plate of such a specific position.

EXAMPLE

Hereinafter, although an Example is given and this invention is demonstrated more concretely, this invention is not restrict | limited by the following example, It is also possible to add suitably and to implement in the range which may be suitable for the meaning of this invention, They are all included in the technical scope of this invention. In addition, the evaluation method of the physical property in a following example is as follows.

(1) Retardation (Re)

Retardation is a parameter defined by the product (△ Nxy × d) of the biaxial refractive index orthogonal (△ Nxy = | nx-ny |) on the film and the film thickness d (nm), and shows optical isotropy and anisotropy It is a measure. Anisotropy (ΔNxy) of biaxial refractive index was obtained by the following method. Using a molecular orientation system (Oji Keisoku Instruments Co., Ltd., MOA-6004 type molecular orientation system), the slow axis direction of the film was obtained, and the slow axis direction was 4 cm x 2 cm so as to be parallel to the long side of the sample for measurement. The rectangle was cut out and it was set as the sample for a measurement. Regarding this sample, the biaxial orthogonal refractive index (refractive index in the ground axis direction: ny, the refractive index in the direction orthogonal to the slow axis direction: nx), and the refractive index nz in the thickness direction were measured by the Abbe refractometer (manufactured by Atago, NAR). The absolute value (| nx-ny |) of the said biaxial refractive index difference was made into the anisotropy ((DELTA) Nxy) of a refractive index. The thickness d (nm) of the film was measured using the electric micrometer (Millitron 1245D by Pineryuf Co., Ltd.), and the unit was converted into nm. Retardation Re was calculated | required from the product ((DELTA) Nxyxd) of the refractive index anisotropy ((DELTA) Nxy) and the film thickness d (nm).

(2) rigid amorphous fraction

The rigid amorphous fraction is represented by the above formula (1) and is indirectly calculated from the values of the operating amorphous fraction and the mass fraction crystallinity.

The movable amorphous fraction was obtained by using the reversible heat capacity difference ΔCp (J / (g · K)) at Tg of the reversible heat capacity curve obtained by temperature-modulated DSC measurement using a differential scanning calorimeter (manufactured by TA Instrument, Q100). A parameter defined by an expression.

Movable amorphous fraction = ((ΔCp of sample) / (ΔCp of complete amorphous)) × 100 (wt%)

In the case of polyethylene terephthalate, ΔCp of 0.4052 (J / (g · K)) is completely amorphous. The sample was weighed at 2.0 ± 0.2 mg in an aluminum pan, and measured at an average temperature rising rate of 5.0 ° C./min and a modulation cycle of 60 sec in MDSC (registered trademark) heat only mode. Measurement data was collected at a sampling frequency of 5 Hz. Indium and sapphire were used for the calibration of temperature and calorie, and for the calibration of specific heat.

Hereinafter, the calculation method of Tg and (DELTA) Cp is shown. First, by plotting the first derivative F '(T) of the temperature T of the reversible heat capacity curve F (T), taking a moving average for every 2401 points, performing a smoothing process, and then reading the value of the temperature at the peak top. Tg was calculated. Next, the straight line G (T) which passes two points of the point A (Tg-15, F (Tg-15)) and the point B (Tg + 15, F (Tg + 15)) was calculated | required. Subsequently, in the range of Tg-15 ≦ T ≦ Tg + 15, the temperature at which F (T) -G (T) became minimum was T1 and the maximum temperature was set at T2. Here, T1 was the point corresponding to the start temperature of the glass transition, and T2 corresponds to the end temperature of the glass transition, thereby obtaining a value of ΔCp by ΔCp = F (T2) -F (T1).

The mass fraction crystallinity degree χ was computed by the following formula using the value d (g / cm <^3> ) of the density obtained using the density gradient tube of the water / calcium nitrate system according to JISK7112.

χ = (dc / d) × ((d-da) / (d-dc)) × 100 (wt%)

Where dc is the density of the full crystal and da is the density of the full amorphous.

In the case of polyethylene terephthalate, dc = 1.498 (g / cm ³ ) and da = 1.335 (g / cm ³ ).

(3) Orientation degree to the film surface of the (100) plane

The orientation degree with respect to the film surface of the (100) plane uses the half width of the diffraction intensity profile of the (100) plane obtained by the wide-angle X-ray diffraction measurement using the X-ray diffraction apparatus (RINT2100PC by Rigaku Corporation). Is a parameter defined by the following formula.

Orientation degree with respect to the film surface of the (100) plane = (180-half-width) / 180

The measurement was performed by the Schultz reflection method by attaching the RINT2000 goniometer which can be attached to a RINT2100PC, and the versatile sample stand for poles. The sample was cut out in a circular shape having a diameter of 5 cm and attached to the sample stage so that the slow axis direction coincided with the β = 90 and 270 degree directions. The details of the measurement conditions are tube voltage = 40kV, tube current = 40mA, 2θ fixed angle = 25.830 degrees, divergence vertical limit = 1.2mm, diverging slit = 1 degree, scattering slit 1 degree, light receiving slit 0.30mm, β = 0 And in the state moved to each of 180 degrees, the control target is the reflection α, and the measurement method is FT, the starting position = 15.000 degrees, the ending position = 90.000 degrees, the step width = 0.500 degrees, and the counting time = 2.0 sec. did.

Hereinafter, the calculation method of the orientation degree with respect to the film surface of the (100) surface is shown. First, the diffraction intensity profile I (α) (15 ≦ α ≦ 90) at β = 0 and 180 degrees is corrected for absorption of incident X-rays by the following equation, and the diffraction intensity at each β A profile J (α) (15 ≦ α ≦ 90) was obtained.

J (α) = I (α) × (1-exp (-2μt / sinθ)) / (1-exp (-2μt / (sinθcos (90-α))))

Where μ is the linear absorption coefficient of the CuKα line, μ = 9.02 (/ cm) for polyethylene terephthalate, t is the sample thickness (cm), and θ is 12.915 degrees corresponding to half of the 2θ fixed angle at the time of measurement. For the obtained J (α) (15 ≦ α ≦ 90), the horizontal axis is α ′ (α ′ = α at β = 0 degrees, α ′ = 180-α at β = 180 degrees), and the vertical axis at each α ′. By setting the diffraction intensity to, the diffraction intensity profile at β = 0 and 180 degrees was connected to obtain a diffraction intensity profile J (α ′) (15 ≦ α ′ ≦ 165). However, the diffraction intensity at α '= 90 degrees was used as the average of the value at β = 0 degrees and the value at β = 180 degrees. Subsequently, fitting J (α ') (15 ≦ α ′ ≦ 165) with a pseudo fork function, the diffraction intensity profile K (α ′) for all α ′ was obtained. A straight line connecting the diffraction intensity at α '= 0 and 180 degrees from K (α') was subtracted as a baseline, and using the half width of the obtained diffraction intensity profile L (α '), (180-half width) / 180 By this, the degree of orientation with respect to the film surface of the (100) plane was calculated.

(4) rainbow stain observation

A polyethylene terephthalate-based resin film made by the method described below was attached to one side of a polarizer made of PVA and iodine so that the absorption axis of the polarizer and the orientation major axis of the film were perpendicular to each other, and a commercially available TAC film was attached to the opposite side to form a polarizing plate. . The obtained polarizing plate was substituted with the polarizing plate of the emission light side which originally existed in the commercial liquid crystal display device (REGZA 43J10X by Toshiba Corporation). Moreover, the polarizing plate was substituted so that a polyethylene terephthalate-type resin film might become a visual recognition side so that the absorption axis of a polarizing plate might correspond with the absorption axis direction of the polarizing plate originally attached to the liquid crystal display device. The liquid crystal display device has a light source for emitting excitation light and a backlight light source including a KSF phosphor. When the emission spectrum of the backlight light source of this liquid crystal display device was measured using the Hamamatsu Photonics multichannel spectrometer PMA-12, the emission spectrum which has a peak top in 448 nm, 533 nm, and 630 nm is observed, and the half width of each peak top is observed. Was 2 nm to 49 nm. In addition, the exposure time at the time of spectrum measurement was 20 msec. A white image was displayed on the liquid crystal display device thus produced, visually observed from the front and inclined directions of the display, and the occurrence of rainbow spots was determined as follows. The observation angle was an angle formed by a line drawn in the normal direction (vertical) from the center of the screen of the display and a line connecting the center of the display and the eye position at the time of observation.

(Double-circle): A rainbow spot was not observed in the range of observation angle 0-60 degree | times.

(Circle): Some light rainbow stain was observed in the range of 0-60 degree of observation angles.

X: Rainbow spots were observed clearly in the range of observation angle 0-60 degree | times.

(Manufacture example 1-polyester A)

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

After completion of the polycondensation reaction, the filtration treatment was performed with a Naslon filter having a 95% cut diameter of 5 μm, extruded into a strand form from the nozzle, and cooled using a cooling water that had previously been subjected to filtration treatment (pore diameter: 1 μm or less). It solidified and cut into pellets. The intrinsic viscosity of the obtained polyethylene terephthalate resin (A) was 0.62 dl / g, and the inert particles and the internal precipitated particles were substantially not contained. (Hereinafter abbreviated as PET (A).)

(Production Example 2-Polyester B)

10 parts by mass of dried ultraviolet absorber (2,2 '-(1,4-phenylene) bis (4H-3,1-benzooxazin-4-one), PET (A) containing no particles (intrinsic viscosity (0.62 dl / g) 90 parts by mass were mixed and a polyethylene terephthalate resin (B) containing an ultraviolet absorbent was obtained using a kneading extruder. (Hereinafter abbreviated as PET (B).)

(Manufacture example 3-preparation of adhesive modification coating liquid)

The transesterification reaction and polycondensation reaction are performed by a conventional method, and 46 mol% of terephthalic acids, 46 mol% of isophthalic acids, and 5-sulfonatoisophthalate 8 as a dicarboxylic acid component (to the whole dicarboxylic acid component) The water-dispersible sulfonic-acid metal base containing copolymerized polyester resin of 50 mol% of ethylene glycol and 50 mol% of neopentylglycol was prepared as mol% and the glycol component (to the whole glycol component). Subsequently, after mixing 51.4 mass parts of water, 38 mass parts of isopropyl alcohol, 5 mass parts of n-butyl cellosolve, and 0.06 mass part of nonionic surfactants, it heat-stirring and when it reaches 77 degreeC, the said water-dispersible sulfonic acid After adding 5 parts by mass of the metal base-containing copolymerized polyester resin and continuing stirring until there is no lump of the resin, the aqueous resin dispersion is cooled to room temperature, and the uniform water dispersible copolymer polyester resin liquid having a solid concentration of 5.0% by mass. Got. Furthermore, after disperse | distributing 3 mass parts of aggregated silica particle (The Fuji Silysia Co., Ltd. product, Silysia 310) to 50 mass parts of water, the aqueous dispersion of silicone 310 is 99.46 mass parts of said water-dispersible copolymer polyester resin liquid. Mass part was added, 20 mass parts of water were added stirring, and the adhesive modification coating liquid was obtained.

(Example 1)

90 parts by mass of PET (A) resin pellets containing no particles and 10 parts by mass of PET (B) resin pellets containing an ultraviolet absorber as a raw material for the base film intermediate layer were dried under reduced pressure (1 Torr) for 6 hours at 135 ° C. Then, it supplied to Extruder 2 (for intermediate | middle layer II layers), PET (A) was dried by the conventional method, and was supplied to Extruder 1 (for outer layer I layer and outer layer III layer), respectively, and it melt | dissolved at 285 degreeC. After filtering these 2 types of polymers by the medium (95% cut of 10 micrometers of nominal filtration) of a stainless sintered compact, respectively, it laminated | stacked in 2 types of three-layer joining blocks, and extruded into a sheet form from detention, The electrostatically applied cast method was wound around a casting drum having a surface temperature of 30 ° C. to solidify and cooled to prepare an unstretched film. At this time, the discharge amount of each extruder was adjusted so that ratio of thickness of I layer, II layer, and III layer might be set to 10:80:10.

Subsequently, after apply | coating the said adhesive modification coating liquid so that the application amount after drying may be set to 0.08 g / m <2> on both surfaces of this unstretched PET film by the reverse roll method, it dried at 80 degreeC for 20 second.

The unstretched film on which this coating layer was formed was guided by a tenter stretching machine, guided to the hot air zone at a temperature of 130 ° C. while holding the end of the film with a clip, and stretched at a distortion rate of 13.8% / sec so as to be 5.5 times in the width direction. did. Next, while maintaining the width drawn in the width direction, heat treatment was performed in a hot air zone having a temperature of 180 ° C., and further 3% relaxation treatment was performed in the width direction to obtain a monoaxially oriented PET film having a film thickness of about 60 μm. .

(Example 2)

The unstretched film produced by the same method as Example 1 was guide | induced with a tenter drawing machine, guide | induced to the hot-air zone of 120 degreeC temperature, holding the edge part of a film with a clip, and distortion rate 18.3% / so that it may become 5.5 times in the width direction. stretched to sec. Next, while maintaining the width drawn in the width direction, heat treatment was performed in a hot air zone having a temperature of 180 ° C., and further 3% relaxation treatment was performed in the width direction to obtain a monoaxially oriented PET film having a film thickness of about 60 μm. .

(Example 3)

The unstretched film produced by the same method as Example 1 was guide | induced with a tenter drawing machine, guide | induced to the hot air zone of temperature 118 degreeC, holding | gripping the edge part of a film with a clip, and distortion rate 34.6% / so that it may become 5.0 times in the width direction. stretched to sec. Next, while maintaining the width drawn in the width direction, heat treatment was performed in a hot air zone having a temperature of 180 ° C., and further 3% relaxation treatment was performed in the width direction to obtain a monoaxially oriented PET film having a film thickness of about 60 μm. .

(Example 4)

The unstretched film produced by the same method as Example 1 was guide | induced with a tenter drawing machine, guide | induced to the hot-air zone of temperature 107 degreeC, holding | gripping the edge part of a film with a clip, and distortion rate 34.6% / so that it may become 5.0 times in the width direction. stretched to sec. Next, while maintaining the width drawn in the width direction, heat treatment was performed in a hot air zone having a temperature of 180 ° C., and further 3% relaxation treatment was performed in the width direction to obtain a monoaxially oriented PET film having a film thickness of about 60 μm. .

(Example 5)

Except for changing the thickness, the unstretched film produced in the same manner as in Example 1 was guided by a tenter stretching machine, guided to the hot air zone at a temperature of 125 ° C. while holding the end of the film with a clip, and 5.5 times in the width direction, It extended | stretched at the distortion rate 18.3% / sec. Next, while maintaining the width drawn in the width direction, heat treatment was performed in a hot air zone at a temperature of 180 ° C., and further 3% relaxation treatment was performed in the width direction to obtain a monoaxially oriented PET film having a film thickness of about 50 μm. .

(Example 6)

The unstretched film produced by the same method as Example 1 was guide | induced with a tenter drawing machine, guide | induced to the hot-air zone of temperature 130 degreeC, holding | gripping the edge part of a film with a clip, and distortion rate 13.8% / so that it may become 5.5 times in the width direction. stretched to sec. Next, while maintaining the width drawn in the width direction, heat treatment was performed in a hot air zone having a temperature of 200 ° C., and further 3% relaxation treatment was performed in the width direction to obtain a monoaxially oriented PET film having a film thickness of about 60 μm. .

(Example 7)

The unstretched film produced by the same method as Example 1 was guide | induced with a tenter drawing machine, guide | induced to the hot-air zone of temperature 120 degreeC, holding | gripping the edge part of a film with a clip, and twisting speed 20.8% / so that it may become 6.0 times in the width direction. stretched to sec. Next, while maintaining the width drawn in the width direction, heat treatment was performed in a hot air zone at a temperature of 180 ° C., and further 3% relaxation treatment was performed in the width direction to obtain a monoaxially oriented PET film having a film thickness of about 50 μm. .

(Comparative Example 1)

The unstretched film produced by the same method as Example 1 was guide | induced with a tenter drawing machine, guide | induced to the hot-air zone of temperature 90 degreeC, holding | gripping the edge part of a film with a clip, and distortion rate 12.5% / so that it may become 4.0 times in the width direction. stretched to sec. Next, while maintaining the width drawn in the width direction, heat treatment was performed in a hot air zone having a temperature of 180 ° C., and further 3% relaxation treatment was performed in the width direction to obtain a monoaxially oriented PET film having a film thickness of about 60 μm. .

(Comparative Example 2)

The unstretched film produced by the same method as Example 1 was guide | induced with a tenter drawing machine, guide | induced to the hot-air zone of temperature 130 degreeC, holding | gripping the edge part of a film with a clip, and distortion rate 13.8% / so that it may become 5.5 times in the width direction. stretched to sec. Next, while maintaining the width | stretched width | variety in the width direction, it heat-processed in the hot-air zone of the temperature of 240 degreeC, and further performed 3% relaxation treatment in the width direction, and obtained the uniaxially-oriented PET film with a film thickness of about 60 micrometers. .

Table 1 shows the results measured on the PET films obtained in Examples and Comparative Examples.

TABLE 1

Industrial availability

If it is a liquid crystal display device, a polarizing plate, and a polarizer protective film of this invention, even if it diversifies the wavelength spectrum of the backlight light source by the wide color gamut of a liquid crystal display device, and thins a polarizer protective film, rainbow spots can be suppressed.

Claims (4)

Light polarizer protective film which consists of a polyethylene terephthalate resin film which satisfy | fills following (1) and (2):
(1) Retardation is 3000 nm or more and 30000 nm or less
(2) The rigid amorphous fraction represented by the following formula is 33 wt% or more.
(Rigid amorphous fraction (wt%)) = 100- (movable amorphous fraction (wt%))-(mass fraction crystallinity (wt%)). The method of claim 1,
A polarizer protective film, wherein the polyethylene terephthalate resin film further satisfies the following (3):
(3) The orientation degree with respect to the film surface of the (100) plane measured by X-ray diffraction is 0.7 or less. The polarizing plate in which the polarizer protective film of Claim 1 or 2 was laminated | stacked on at least one surface of polarizer. A liquid crystal display device having a backlight light source, two polarizing plates, and a liquid crystal cell disposed between the two polarizing plates,
The liquid crystal display device of at least one of the said two polarizing plates is a polarizing plate of Claim 3.