JP6182858B2 - Liquid crystal display device, polarizing plate and polarizer protective film - Google Patents

Description

  The present invention relates to a liquid crystal display device, a polarizing plate, and a polarizer protective film. Specifically, the present invention relates to a liquid crystal display device, a polarizing plate, and a polarizer protective film that have good visibility and are suitable for thinning.

  A polarizing plate used in a liquid crystal display (LCD) usually has a configuration in which a polarizer in which iodine is dyed on polyvinyl alcohol (PVA) or the like is sandwiched between two polarizer protective films. As the film, a triacetyl cellulose (TAC) film is usually used. In recent years, with the thinning of LCDs, there has been a demand for thinner polarizing plates. However, if the thickness of the TAC film used as the protective film is reduced for this purpose, sufficient mechanical strength cannot be obtained, and the moisture permeability becomes high and the polarizer is likely to deteriorate. Further, TAC films are very expensive, and there is a strong demand for inexpensive alternative materials.

  Therefore, it has been proposed to use a polyester film instead of the TAC film so that the polarizing plate can be made thin so that high durability can be maintained even if the thickness is small as a polarizer protective film (Patent Documents 1 to 3). ).

JP 2002-116320 A JP 2004-219620 A JP 2004-205773 A

  The polyester film is superior to the TAC film in durability, but unlike the TAC film, the polyester film has birefringence. Therefore, when the polyester film is used as a polarizer protective film, there is a problem that the image quality is deteriorated due to optical distortion. That is, since the polyester film having birefringence has a predetermined optical anisotropy (retardation), when used as a polarizer protective film, a rainbow-like color spot is generated when observed from an oblique direction, and the image quality is deteriorated. . Therefore, in patent documents 1-3, the countermeasure which makes retardation small is made by using copolyester as polyester. However, even in that case, the iridescent color spots could not be completely eliminated.

  The present invention is to solve such a problem, and the object thereof is to cope with the thinning of the liquid crystal display device (that is, has sufficient mechanical strength) and is visually recognized by rainbow-like color spots. It is to provide a liquid crystal display device and a polarizer protective film that do not cause deterioration in properties. The present invention also provides a polarizer protective film that suppresses iris-like colors under a fluorescent lamp and is excellent in adhesion with a hard coat layer, particularly adhesion under high temperature and high humidity (moisture and heat resistance). For the purpose.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that on a polyester film having a specific retardation, an aqueous polyester resin (A), a water-soluble titanium chelate compound, a water-soluble titanium acylate compound, a water-soluble A laminated film provided with a coating layer mainly composed of one or more types (B) selected from the group consisting of a zirconium chelate compound and a water-soluble zirconium acylate compound is used as a polarizer protective film and specified. The present inventors have found that the above problem can be solved by using in combination with the backlight light source. More specifically, the inventors pay attention to the refractive index of the coating layer so that the refractive index difference between the polyester film of the base material and the coating layer and the refractive index difference between the coating layer and the hard coat layer are reduced. By controlling the refractive index of the coating layer with the type and content of the resin and additives that make up the coating layer, the adhesion with the hard coat layer and the adhesion under high temperature and high humidity (wet heat resistance) are maintained. However, it has been found that the iris-like color under a fluorescent lamp can be suppressed. The present invention has been completed based on this finding.

That is, a typical present invention is as follows.
Item 1.
A group consisting of an aqueous polyester resin (A) and a water-soluble titanium chelate compound, a water-soluble titanium acylate compound, a water-soluble zirconium chelate compound, and a water-soluble zirconium acylate compound on at least one side of a polyester film having a retardation of 3000 to 30000 nm. For a liquid crystal display device in which a white light source having a continuous emission spectrum, in which a coating layer formed from an aqueous coating solution containing at least one selected from (B) as a main constituent is laminated, is used as a backlight source. Polarizer protective film.
Item 2.
Item 2. The polarizer protective film according to Item 1, wherein a mixing ratio (A / B) of (A) and (B) is from 10/90 to 95/5 in terms of mass.
Item 3.
Item 3. The aqueous polyester resin (A) is a copolymerized polyester resin containing 1 to 10 mol% of an aromatic dicarboxylic acid component containing a sulfonic acid metal base with respect to the total dicarboxylic acid component of the polyester. Polarizer protective film.
Item 4.
Item 4. The polarizer protective film according to any one of Items 1 to 3, wherein the glass transition temperature of the aqueous polyester resin (A) is 40 ° C. or higher.
Item 5.
Item 5. The polarizer protective film according to any one of Items 1 to 4, wherein the ratio of the retardation of the polyester film to the retardation in the thickness direction (Re / Rth) is 0.2 or more.
Item 6.
Item 6. The polarizer protective film according to any one of Items 1 to 5, wherein the polyester film comprises three or more layers, and an ultraviolet absorber is contained in a layer other than the outermost layer, and the light transmittance at 380 nm is 20% or less.
Item 7.
Item 7. The polarizer protective film according to any one of Items 1 to 6, wherein a hard coat layer made of an electron beam or an ultraviolet curable acrylic resin or a siloxane-based thermosetting resin is further laminated on the coating layer.
Item 8.
Item 1-6, wherein the coating layer has one or more layers selected from the group consisting of an antiglare layer, an antireflection layer, a low reflection layer, a low reflection antiglare layer, an antireflection antiglare layer, and an antistatic layer. The polarizer protective film in any one of.
Item 9.
The polarizing plate for liquid crystal display devices which makes the backlight light source the white light source which has the continuous emission spectrum by which the polarizer protective film in any one of claim | item 1 -8 was laminated | stacked on the at least one side of the polarizer.
Item 10.
Item 10. The polarizing plate for a liquid crystal display device according to item 9, wherein the polarizer protective film is laminated on the polarizer via an ultraviolet curable, electron beam curable, or thermosetting adhesive.
Item 11.
Item 11. A liquid crystal display device comprising the polarizing plate according to Item 9 or 10, wherein the backlight source is a white light source having a continuous emission spectrum.
Item 12.
Item 11. The liquid crystal display device according to item 11, wherein the polarizing plate disposed on the emission light side with respect to the liquid crystal is the polarizing plate according to item 9 or 10.
Item 13.
Item 13. The liquid crystal display device according to item 11 or 12, wherein the white light source having the continuous emission spectrum is a white light emitting diode.

  The liquid crystal display device, the polarizing plate and the polarizer protective film of the present invention have good visibility in which no noticeable rainbow-like color spots are observed at any viewing angle. Further, the polarizer protective film of the present invention is excellent in antireflection property to suppress reflection of external light, glare, iris color, etc. when a hard coat layer is laminated on the coating layer, and the hard coat layer And adhesion under high temperature and high humidity (wet heat resistance). In a preferred embodiment, the polarizer protective film of the present invention has a mechanical strength suitable for thinning.

  In general, the liquid crystal panel includes a rear module, a liquid crystal cell, and a front module in order from the backlight source side toward the image display side (viewing side or emission light side). 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, and a polarizing plate disposed on the opposite side. Here, the polarizing plate is disposed on the backlight source side in the rear module, and is disposed on the image display side (viewing side or emission light side) in the front module.

  The liquid crystal display device of the present invention comprises at least a backlight source and a liquid crystal cell disposed between two polarizing plates. Moreover, you may have suitably other structures other than these, for example, a color filter, a lens film, a diffusion sheet, an antireflection film etc. suitably.

  The configuration of the backlight light source may be an edge light method using a light guide plate, a reflection plate, or the like, or a direct type, but in the present invention, as a backlight light source of a liquid crystal display device, It is preferable to use a white light source having a continuous and broad emission spectrum. Here, the continuous and broad emission spectrum means an emission spectrum in which there is no wavelength at which light intensity becomes zero in a wavelength region of at least 450 nm to 650 nm, preferably in a visible light region. Examples of such a white light source having a continuous and broad emission spectrum include a white light emitting diode (white LED). The white LED includes a phosphor type, that is, an element that emits white light by combining a light emitting diode that emits blue light or ultraviolet light using a compound semiconductor and a phosphor, or an organic light emitting diode (OLED). Etc. are included. Examples of the phosphor include yttrium / aluminum / garnet yellow phosphor and terbium / aluminum / garnet yellow phosphor. Among white LEDs, white light-emitting diodes consisting of a light-emitting element that combines a blue light-emitting diode using a compound semiconductor and a yttrium, aluminum, and garnet yellow phosphor have a continuous and broad emission spectrum and luminous efficiency. Therefore, it is suitable as the backlight light source of the present invention. The method of the present invention is also effective for energy saving by using a light source such as a white LED with low power consumption.

  Fluorescent tubes such as cold cathode tubes and hot cathode tubes that have been widely used as backlight light sources conventionally have only a discontinuous emission spectrum whose emission spectrum has a peak at a specific wavelength. It is difficult to obtain the effects of the present invention.

  The polarizing plate has a configuration in which both sides of a polarizer in which iodine is dyed on PVA or the like are sandwiched between two polarizer protective films. In the present invention, at least one of the polarizer protective films constituting the polarizing plate is used. A polyester film having a specific range of retardation is used.

The mechanism for suppressing the occurrence of rainbow-like color spots according to the above aspect is considered as follows.
When a polyester film having birefringence is disposed on one side of the polarizer, the linearly polarized light emitted from the polarizer is disturbed when passing through the polyester film. The transmitted light shows an interference color peculiar to retardation which is the product of birefringence and thickness of the polyester film. Therefore, if a discontinuous emission spectrum such as a cold cathode tube or a hot cathode tube is used as the light source, the transmitted light intensity varies depending on the wavelength, and a rainbow-like color spot is generated (see: 15th Micro Optical Conference Proceedings, No. 1). 30-31).

  In contrast, white light emitting diodes usually have a continuous and broad emission spectrum in a wavelength region of at least 450 nm to 650 nm, preferably in the visible light region. And since the interference color spectrum by the transmitted light which permeate | transmitted the birefringent body becomes an envelope shape, it becomes possible to obtain the spectrum similar to the light emission spectrum of a light source by controlling the retardation of a polyester film. In this way, by making the emission spectrum of the light source similar to the envelope shape of the interference color spectrum by the transmitted light that has passed through the birefringent body, visibility is not noticeable without rainbow-like color spots. It is thought to improve.

  From the above principle, in the present invention, a white light emitting diode having a broad emission spectrum is used as a light source, so that the envelope shape of the spectrum of transmitted light can be approximated to the emission spectrum of the light source with only a relatively simple configuration, and as a result, liquid crystal It is thought that it is possible to suppress rainbow spots on the display.

(Polyester film: base film)
The polyester film used as the base film of the polarizer protective film of the present invention is preferably an oriented polyester film having a retardation of 3000 to 30000 nm. When the retardation is less than 3000 nm, when used as a polarizer protective film, it exhibits a strong interference color when observed from an oblique direction, so the envelope shape is different from the emission spectrum of the light source, and good visibility cannot be ensured. . The lower limit of the preferable retardation is 4500 nm or more, next preferably 5000 nm or more, more preferably 6000 nm or more, still more preferably 8000 nm or more, and still more preferably 10,000 nm or more.

  On the other hand, the upper limit of retardation is 30000 nm. Even if a polyester film having a retardation of more than that is used, it is not only possible to substantially improve the visibility, but also because the film thickness becomes considerably thick and the handling property as an industrial material is reduced, it is preferable. Absent.

  The retardation of the polyester film can be obtained by measuring the biaxial refractive index and thickness, or can be obtained by using a commercially available automatic birefringence measuring device such as KOBRA-21ADH (Oji Scientific Instruments). . In this document, retardation means in-plane retardation.

  In the present invention, at least one of the polarizer protective films is a polarizer protective film having the specific retardation. The arrangement of the polarizer protective film having the specific retardation is not particularly limited, but the polarizer protective film on the incident light side of the polarizing plate arranged on the incident light side of the liquid crystal display device, or the polarized light arranged on the emission light side It is preferable that the polarizer protective film on the emission light side of the plate is a polarizer protective film made of a polyester film having the specific retardation. A particularly preferred embodiment is an embodiment in which the polarizer protective film on the exit light side of the polarizing plate disposed on the exit light side is a polyester film having the specific retardation. When the polyester film is disposed at a position other than the above, the polarization characteristics of the liquid crystal cell may be changed.

  The polarizing plate of the present invention has a structure in which both sides of a polarizer in which iodine is dyed on polyvinyl alcohol (PVA) or the like are sandwiched between two polarizer protective films, and any one of the polarizer protective films is specified above. It is a polarizing plate protective film which has this retardation. As the other polarizer protective film, it is preferable to use a film having no birefringence such as a TAC film, an acrylic film, and a norbornene-based film.

The polyester film can be obtained by condensing a dicarboxylic acid and a diol.
Examples of the dicarboxylic acid component that can be used for producing the polyester film include terephthalic acid, isophthalic acid, orthophthalic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1 , 5-Naphthalenedicarboxylic acid, diphenylcarboxylic acid, diphenoxyethanedicarboxylic acid, diphenylsulfonecarboxylic acid, anthracenedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid , Hexahydroterephthalic acid, hexahydroisophthalic acid, malonic acid, dimethylmalonic acid, succinic acid, 3,3-diethylsuccinic acid, glutaric acid, 2,2-dimethylglutaric acid, adipic acid, 2-methyladipic acid, trimethyl Horse mackerel Phosphate, pimelic acid, azelaic acid, dimer acid, sebacic acid, suberic acid, dodecamethylene dicarboxylic acid and the like.

  Examples of the diol component that can be used for producing the polyester film include ethylene glycol, propylene glycol, hexamethylene glycol, neopentyl glycol, 1,2-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, decamethylene glycol, 1 , 3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexadiol, 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) sulfone, etc. Can be mentioned.

  Each of the dicarboxylic acid component and the diol component constituting the polyester film may be used alone or in combination of two or more. Specific polyester resins constituting the polyester film include, for example, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and preferably polyethylene terephthalate and polyethylene naphthalate. These resins are excellent in transparency and excellent in thermal and mechanical properties, and the retardation can be easily controlled by stretching. In particular, polyethylene terephthalate is the most suitable material because it has a large intrinsic birefringence and a large retardation can be obtained relatively easily even if the film is thin.

  Moreover, in order to suppress deterioration of optical functional pigments such as iodine pigments, it is desirable that the protective film of the present invention has a light transmittance of 20% or less at a wavelength of 380 nm. The light transmittance at 380 nm is more preferably 15% or less, further preferably 10% or less, and particularly preferably 5% or less. If the light transmittance is 20% or less, the optical functional dye can be prevented from being deteriorated by ultraviolet rays. In addition, the transmittance | permeability in this invention is measured by the perpendicular | vertical method with respect to the plane of a film, and can be measured using a spectrophotometer (for example, Hitachi U-3500 type).

  Setting the transmittance at a wavelength of 380 nm of the protective film of the present invention to 20% or less includes adding an ultraviolet absorber in the film, applying a coating solution containing the ultraviolet absorber to the film surface, and an ultraviolet absorber. This can be achieved by appropriately adjusting the type, concentration, and thickness of the film. The ultraviolet absorber used in the present invention is a known substance. Examples of the ultraviolet absorber include an organic ultraviolet absorber and an inorganic ultraviolet absorber, and an organic ultraviolet absorber is preferable from the viewpoint of transparency.

  Examples of the organic ultraviolet absorber include benzotriazole, benzophenone, cyclic imino ester, and combinations thereof, but are not particularly limited as long as the absorbance is within the range defined by the present invention. From the viewpoint of durability, benzotoazole and cyclic imino ester are particularly preferable. When two or more kinds of ultraviolet absorbers are used in combination, ultraviolet rays having different wavelengths can be absorbed simultaneously, so that the ultraviolet absorption effect can be further improved. When the ultraviolet absorber is blended with the polyester film, the polyester film is preferably composed of three or more layers, and the ultraviolet absorber is blended with a layer other than the outermost layer (that is, the intermediate layer).

  Examples of the benzophenone ultraviolet absorber, benzotriazole ultraviolet absorber, and acrylonitrile ultraviolet absorber include 2- [2′-hydroxy-5 ′-(methacryloyloxymethyl) phenyl] -2H-benzotriazole, 2- [2′-hydroxy-5 ′-(methacryloyloxyethyl) phenyl] -2H-benzotriazole, 2- [2′-hydroxy-5 ′-(methacryloyloxypropyl) phenyl] -2H-benzotriazole, 2,2 ′ -Dihydroxy-4,4'-dimethoxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 2,4-di-tert-butyl-6- (5-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. Examples of the cyclic imino ester UV absorber include 2,2 ′-(1,4 -Phenylene) bis (4H-3,1-benzoxazinon-4-one), 2-methyl-3,1-benzoxazin-4-one, 2-butyl-3,1-benzoxazin-4-one, Examples thereof include 2-phenyl-3,1-benzoxazin-4-one, but are not particularly limited thereto.

  Moreover, it is also a preferable aspect to contain various additives in the range which does not prevent the effect of this invention other than an ultraviolet absorber. Examples of additives include inorganic particles, heat resistant polymer particles, alkali metal compounds, alkaline earth metal compounds, phosphorus compounds, antistatic agents, light proofing agents, flame retardants, thermal stabilizers, antioxidants, and antigelling agents. And surfactants. Moreover, in order to show high transparency, it is also preferable that a polyester film does not contain a particle | grain substantially. “Substantially free of particles” means, for example, in the case of inorganic particles, when the inorganic element is quantified by fluorescent X-ray analysis, the content is 50 ppm or less, preferably 10 ppm or less, particularly preferably the detection limit or less. Means quantity.

(Coating layer)
The polarizer protective film of the present invention has an aqueous polyester resin (A), a water-soluble titanium chelate compound, a water-soluble titanium acylate compound, a water-soluble zirconium chelate compound, and a water-soluble zirconium acyl compound on at least one surface. It has a coating layer made of a resin composition whose main constituent is at least one (B) selected from the group consisting of rate compounds. The composition preferably has a mixing ratio (mass ratio) of (A) / (B) of 10/90 to 95/5.

  This resin composition is heated with heat during the stretching process of the base film, so that at least one of a titanium chelate compound, a titanium acylate compound, a zirconium chelate compound, or a zirconium acylate compound (B) is a polyester resin. A uniform film is formed by the crosslinking reaction. That is, since the metal chelate compound or metal acylate compound is decomposed by heat treatment, it does not exist in the coating layer in a state where it is added to the coating solution.

Therefore, the content of the metal chelate compound or metal acylate compound in the coating solution is calculated from the content of the metal element (Ti or Zr) in the coating layer after the heat treatment as follows.
(1) First, the type of chelate or acylate contained in the coating solution is identified from the chelate or acylate residue in the coating layer.
(2) Next, the content of the metal chelate compound or metal acylate compound in the coating solution is calculated from the content of the metal element (Ti or Zr) in the coating layer.

  The refractive index of the coating layer is higher than that of the polyester resin (A) alone by increasing the composition ratio of at least one of the titanium chelate compound, the titanium acylate compound, the zirconium chelate compound, or the zirconium acylate compound (B). Can also be high.

  Increasing the refractive index of the coating layer can also be achieved by including metal fine particles, but by including the metal fine particles, the stretchability of the coating layer and the adhesion between the hard coat layer and the base film are descend.

  In the polyester resin (A) used in the present invention, an active site such as a hydroxyl group or a carboxyl group may be introduced into the molecular chain. A cross-linking reaction takes place in this place, resulting in a dense film.

  Moreover, in order to give the same crosslinkability with an acrylic resin, it is necessary to introduce a crosslinkable functional group. However, since the refractive index of the acrylic resin itself is low, even when a titanium chelate compound, a titanium acylate compound, a zirconium chelate compound, or a zirconium acylate compound is used in combination, the refractive index is controlled to be the same as that of the coating layer of the present invention. It is difficult.

  Furthermore, the polyester resin (A) which is a constituent component of the coating layer is involved in adhesion to the base polyester film. That is, when the composition ratio (A / B) between the water-based polyester resin (A) and the compound (B) is less than 10/90 in terms of mass, the adhesion with the base film is lowered, and the coating layer is Stretchability is reduced and does not become uniform during stretching. Therefore, the transparency required for optical applications is lowered, and the adhesion with the hard coat layer formed on the coating layer becomes a problem.

  On the other hand, when the composition ratio (A / B) between the aqueous polyester resin (A) and the compound (B) exceeds 95/5 in terms of mass, a water-soluble titanium acylate compound, a water-soluble zirconium chelate compound, or Crosslinking by the water-soluble zirconium acylate compound (B) becomes poor, and the refractive index also decreases. For this reason, the adhesion (humidity and heat resistance) under high temperature and high humidity is lowered, and the effect of suppressing iris-like colors under a fluorescent lamp is insufficient.

  The aqueous polyester resin (A) of the present invention can be dissolved or dispersed in water or a water-soluble organic solvent (for example, an aqueous solution containing less than 50% by mass of alcohol, alkyl cellosolve, ketone, or ether). Meaning polyester resin. It is possible to impart water resistance to the polyester resin by introducing a hydrophilic group such as a hydroxyl group, a carboxyl group, a sulfonic acid group, a phosphoric acid group, or an ether group into the molecular chain of the polyester resin. Among the hydrophilic groups, sulfonic acid groups are preferable from the viewpoint of coating film properties and adhesion.

  When the sulfonic acid group is introduced into the polyester, the sulfonic acid compound is more preferably 1 to 10 mol% in the total acid component of the polyester. When the amount of the sulfonic acid group is less than 1 mol%, the polyester resin does not exhibit water, and a water-soluble titanium chelate compound, a water-soluble titanium acylate compound, a water-soluble zirconium chelate compound, or a water-soluble zirconium acylate compound Since the compatibility with at least one of (B) also decreases, it becomes difficult to obtain a uniform and transparent coating layer. Moreover, when the amount of sulfonic acid groups exceeds 10 mol%, it becomes easy to be inferior to the adhesiveness (humidity heat resistance) under high temperature and high humidity.

  Furthermore, the glass transition temperature of the aqueous polyester resin (A) is preferably 40 ° C. or higher. For this reason, the acid component of the polyester resin (A) is preferably composed mainly of an aromatic group such as terephthalic acid, isophthalic acid, or naphthalenedicarboxylic acid. The glycol component is preferably a glycol having a relatively small carbon number such as ethylene glycol, propane glycol, 1,4-butanediol, or neopentyl glycol, or an aromatic system such as an ethylene oxide adduct of bisphenol A. Further, as a raw material for the polyester resin (A), a rigid component such as biphenyl, or a dicarboxylic acid component or diol component having a high refractive index atom such as bromine or sulfur may be used as long as the physical properties of the film do not deteriorate. Good. When the glass transition temperature of the polyester resin (A) is less than 40 ° C., the adhesiveness (humidity heat resistance) under high temperature and high humidity tends to be insufficient. Furthermore, since the refractive index of the polyester resin (A) also decreases, the refractive index of the coating layer also decreases. As a result, the suppression of the iris color under the fluorescent lamp tends to be insufficient.

  The other main component of the coating layer is at least one (B) of a water-soluble titanium chelate compound, a water-soluble titanium acylate compound, a water-soluble zirconium chelate compound, or a water-soluble zirconium acylate compound. The above water-soluble means to dissolve in an aqueous solution containing less than 50% by mass of water or a water-soluble organic solvent.

  Examples of water-soluble titanium chelate compounds include diisopropoxybis (acetylacetonato) titanium, isopropoxy (2-ethyl-1,3-hexanediolato) titanium, diisopropoxybis (triethanolaminato) titanium, di -N-butoxybis (triethanolaminato) titanium, hydroxybis (lactato) titanium, ammonium salt of hydroxybis (lactato) titanium, titanium beloxocitrate ammonium salt and the like.

  Examples of the water-soluble titanium acylate compound include oxotitanium bis (monoammonium oxalate), and examples of the water-soluble zirconium compound include zirconium tetraacetylacetonate and zirconium acetate.

  In the coating layer, a resin other than the main component, for example, an acrylic resin, a polyurethane resin, a polyester resin, an alkyd resin, a vinyl resin such as polyvinyl alcohol, etc. is used in a range that does not affect the effect of the present invention. It doesn't matter. Further, the combined use of the crosslinking agent is not particularly limited as long as the effect of the present invention is not affected. Examples of crosslinking agents that can be used include adducts of urea, melamine, benzoguanamine, and the like with formaldehyde, amino resins such as alkyl ether compounds composed of these adducts and alcohols having 1 to 6 carbon atoms, polyfunctional epoxy compounds, A polyfunctional isocyanate compound, a block isocyanate compound, a polyfunctional aziridine compound, an oxazoline compound, etc. are mentioned.

  In the present invention, the coating liquid used for forming the coating layer includes an aqueous polyester resin (A), a water-soluble titanium chelate compound, a water-soluble titanium acylate compound, a water-soluble zirconium chelate compound, and a water-soluble An aqueous coating solution mainly comprising at least one type (B) selected from the group consisting of zirconium acylate compounds and an aqueous solvent. When applying the above aqueous coating solution to the surface of the polyester film, an appropriate amount of a known anionic surfactant or nonionic surfactant is added to improve the wettability of the film and coat the coating solution uniformly. It is preferable to do.

  In addition, in the aqueous coating solution, inorganic and / or heat-resistant polymer particles, antistatic agents, ultraviolet absorbers, etc. in order to impart other functions such as handling properties, antistatic properties and antibacterial properties to the film. Additives such as organic lubricants, antibacterial agents, and photo-oxidation catalysts can be included.

As the solvent used in the coating solution, alcohols such as ethanol, isopropyl alcohol, and benzyl alcohol may be mixed in addition to water in a range of less than 50% by mass with respect to the total coating solution.
Furthermore, if it is less than 10 mass%, you may mix in the range which can melt | dissolve organic solvents other than alcohol. However, the total amount of alcohols and other organic solvents in the coating solution is preferably less than 50% by mass.

  In a preferred embodiment, the polarizer protective film has a hard coat layer made of an electron beam, an ultraviolet curable acrylic resin, or a siloxane thermosetting resin on at least one surface of the coating layer.

  Resin that is cured by electron beam or ultraviolet ray, has acrylate functional group, for example, relatively low molecular weight polyester resin, polyether resin, acrylic resin, epoxy resin, urethane resin, alkyd resin, spiroacetal resin , Oligomers or prepolymers of polyfunctional compounds such as polybutadiene resins, polythiol polyene resins, polyhydric alcohols, etc., and reactive diluents such as ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, methylstyrene, Monofunctional monomers such as N-vinylpyrrolidone and polyfunctional monomers such as trimethylolpropane tri (meth) acrylate, hexanediol (meth) acrylate, tripropylene glycol di (meth) acrylate , Diethylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, etc. Things can be used.

  In the case of an ultraviolet curable resin, acetophenones, benzophenones, Michler benzoyl benzoate, α-amyloxime ester, tetramethyltyrium monosulfide, thioxanthones, photopolymerization initiators, As a sensitizer, n-butylamine, triethylamine, tri-n-butylphosphine and the like can be mixed and used.

  In any stage of the film production process, the aqueous coating solution is applied to at least one surface of a polyester film (for example, PET film). The solid content concentration of the resin composition in the aqueous coating solution is preferably 2 to 35% by mass, particularly preferably 4 to 15% by mass.

  As a method for applying this aqueous coating solution to a PET film, any known method can be used. For example, reverse roll coating method, gravure coating method, kiss coating method, die coater method, roll brush method, spray coating method, air knife coating method, wire bar coating method, pipe doctor method, impregnation coating method, curtain coating method, etc. These methods are applied alone or in combination.

  In the present invention, the coating layer is preferably formed by applying the aqueous coating solution to an unstretched or uniaxially stretched PET film, drying it, stretching it at least in the uniaxial direction, and then performing a heat treatment. The film coated with the coating solution is guided to a tenter and heated for transverse stretching and heat treatment. At that time, the chelate compound or the acylate compound can form a stable crosslinked coating layer by a thermal crosslinking reaction. On the other hand, in the case of a coating layer obtained by applying and drying the above-mentioned coating solution on a biaxially stretched PET film, the amount of heat is suppressed in order to reduce the deterioration of the transparency of the substrate film due to heat treatment and the change in physical properties. I have to. Therefore, the amount of heat is insufficient to perform the thermal crosslinking reaction, and a uniform crosslinked coating layer cannot be formed.

In the present invention, the coating amount of the finally obtained coating layer is preferably 0.02 to 0.5 g / m ² . If the coating amount of the coating layer is less than 0.02 g / m ² , not only the effect on adhesiveness is almost lost, but also the effect of suppressing iris-like colors under a fluorescent lamp tends to be insufficient. On the other hand, when the coating amount exceeds 0.5 g / m ² , the effect of suppressing the iris color under a fluorescent lamp tends to be insufficient.

(Manufacture of polarizer protective film with hard coat layer)
A hard coat layer can be laminated and used on at least one surface of the polarizer protective film. The hard coat layer is not particularly limited, and a resin compound that polymerizes and / or reacts by drying, heat, chemical reaction, or irradiation with electron beam, radiation, or ultraviolet light can be used. Examples of such curable resins include melamine-based, acrylic-based, silicon-based, and polyvinyl alcohol-based curable resins. These hard coat layers can be obtained by applying a coating liquid for forming a hard coat layer containing the electron beam, the ultraviolet curable acrylic resin or the siloxane thermosetting resin. The coating solution need not be diluted, but may be diluted with an organic solvent according to the viscosity, wettability, coating layer thickness, etc. of the coating solution. The hard coat layer is coated with a coating liquid for forming a hard coat layer on at least one surface of the polarizer protective film, dried as necessary, and then in accordance with the curing conditions of the curable resin. The hard coat layer is formed by curing the coating layer by irradiating with rays or ultraviolet rays and heating.

  In the present invention, the thickness of the hard coat layer is preferably 1 to 15 μm. When the thickness of the hard coat layer is less than 1 μm, the effects on the chemical resistance, scratch resistance, antifouling property and the like as the hard coat layer are almost lost. On the other hand, if the thickness exceeds 15 μm, the flexibility of the hard coat layer is reduced, and the possibility of cracks and the like increases.

The polarizer protective film obtained by laminating the hard coat layer obtained in the present invention can be formed into a good antireflection film by forming an antireflection layer on the hard coat layer. For the formation of such an antireflection layer, a single layer of an inorganic material such as ZnO, TiO ₂ , CeO ₂ , SnO ₂ , ZrO ₂ or the like having a high refractive index or MgF ₂ or SiO ₂ having a low refractive index or a metal material is used. Alternatively, it is performed by providing multiple layers. These layers are formed as a single layer or multiple layers of an application layer made of a resin composition containing vapor deposition, sputtering, plasma CVD, or the like, or a high refractive index or low refractive index inorganic material or metal material.

  The hard coat layer may have an antiglare function (antiglare function) that scatters external light. The antiglare function (antiglare function) can be obtained by forming irregularities on the surface of the hard coat layer. At this time, the haze of the film is preferably 2 to 50%, more preferably 2 to 40%, and particularly preferably 2 to 30%.

  Coating layer used in the present invention (water polyester resin (A) and a water-soluble titanium chelate compound, a water-soluble titanium acylate compound, a water-soluble zirconium chelate compound, and a water-soluble zirconium acylate compound) The coating layer formed from an aqueous coating solution containing (B) as a main constituent) is not only a hard coat layer, but also an antiglare layer, an antireflection layer, a low reflection layer, a low reflection antiglare layer, and an antireflection layer. Excellent adhesion to antiglare layer or antistatic layer. This is because many of these layers are made of a curable resin that is polymerized and / or reacted by drying, heat, chemical reaction, or irradiation with electron beam, radiation, or ultraviolet light. From the viewpoint of preventing reflection from outside light such as LCD and touch panel, it is selected from the group consisting of an antiglare layer, an antireflection layer, a low reflection layer, a low reflection antiglare layer and an antireflection antiglare layer on the coating layer. It is also a preferred embodiment of the present invention to laminate one or more layers. In addition, it is also a preferred embodiment of the present invention that an antistatic layer is laminated from the viewpoint of antistatic. Of the hard coat layer, antiglare layer, antireflection layer, low reflection layer, low reflection antiglare layer, antireflection antiglare layer and antistatic layer, only one type may be provided on the polyester film, You may laminate | stack combining 2 or more types as needed. For example, the antiglare layer and the antistatic layer may be laminated in order, or the antiglare layer may be provided with an antistatic function and the antiglare function and the antistatic function may be combined in one layer. . By providing these layers, an effect of reducing iridescent color spots caused by the polarizing plate can be expected. As the antiglare layer, antireflection layer, low reflection layer, low reflection antiglare layer, antireflection antiglare layer and antistatic layer, known ones can be used. The antistatic layer may be a layer containing a known antistatic agent or a layer containing a conductive polymer such as polythiophene, polypyrrole or polyaniline.

  Further, the polyester film of the present invention can be subjected to corona treatment, coating treatment, flame treatment and the like in order to improve the adhesion to the polarizer.

(Easily adhesive layer with polarizer)
The oriented polyester film which is the polarizer protective film of the present invention has a polyester resin, a polyurethane resin or a polyacrylic resin on the surface opposite to the surface on which the coating layer is provided in order to improve the adhesion to the polarizer. It is preferable to have an easy-adhesion layer containing at least one of the above as a main component. Here, the “main component” refers to a component that is 50% by mass or more of the solid components constituting the easy-adhesion layer. The coating solution used for forming the easy-adhesion layer is preferably an aqueous coating solution containing at least one of a water-soluble or water-dispersible copolymerized polyester resin, an acrylic resin, and a polyurethane resin. Examples of these coating solutions include water-soluble or water-dispersible co-polymers disclosed in Japanese Patent No. 3567927, Japanese Patent No. 3589232, Japanese Patent No. 3589233, Japanese Patent No. 3900191, and Japanese Patent No. 4150982. Examples thereof include a polymerized polyester resin solution, an acrylic resin solution, and a polyurethane resin solution.

  In addition to the above-described embodiment, a polarizer may be laminated on the surface of the polarizer protective film of the present invention provided with the coating layer via an ultraviolet curable, electron beam curable, or thermosetting adhesive. This is a preferred embodiment. As described above, the coating layer of the polarizer protective film of the present invention is excellent in adhesiveness with a curable resin and excellent in adhesiveness with an adhesive such as an ultraviolet curable type, an electron beam curable type, and a thermosetting type. is there. As the ultraviolet curable adhesive, electron beam curable adhesive, and thermosetting adhesive, a conventionally known adhesive can be used for manufacturing a polarizing plate, and is not particularly limited. For example, curable resins disclosed in JP2011-219548, JP2011-186481, JP2011-175273, JP2011-127003, and the like can be used.

The easy-adhesion layer can be obtained by applying the coating solution on one or both sides of an unstretched or longitudinally uniaxially stretched film, drying at 100 to 150 ° C., and further stretching in the transverse direction. The final coating amount of the easy adhesion layer is preferably controlled to 0.05 to 0.20 g / m ² . If the coating amount is less than 0.05 g / m ² , the adhesion with the resulting polarizer may be insufficient. On the other hand, when the coating amount exceeds 0.20 g / m ² , blocking resistance may be lowered.

  It is preferable to add particles to the easy-adhesion layer in order to impart easy slipperiness. The average particle size of the fine particles is preferably 2 μm or less. When the average particle diameter of the particles exceeds 2 μm, the particles easily fall off from the easy adhesion layer. As particles to be included in the easy adhesion layer, for example, titanium oxide, barium sulfate, calcium carbonate, calcium sulfate, silica, alumina, talc, kaolin, clay, calcium phosphate, mica, hectorite, zirconia, tungsten oxide, lithium fluoride, Examples include inorganic particles such as calcium fluoride, and organic polymer particles such as styrene, acrylic, melamine, benzoguanamine, and silicone. These may be added alone to the easy-adhesion layer, or may be added in combination of two or more.

  Moreover, as a method for applying the coating solution, a known method can be used as in the case of the above-described coating layer. For example, reverse roll coating method, gravure coating method, kiss coating method, roll brush method, spray coating method, air knife coating method, wire bar coating method, pipe doctor method, etc. can be mentioned. Or it can carry out in combination.

  In addition, the measurement of the average particle diameter of said particle | grain can be performed with the following description method. Take a picture of the particles with a scanning electron microscope (SEM) and at a magnification such that the size of one smallest particle is 2-5 mm, the maximum diameter of 300-500 particles (between the two most distant points) Distance) is measured, and the average value is taken as the average particle diameter.

  The polyester film which is the polarizer protective film of the present invention can be produced according to a general method for producing a polyester film. For example, the polyester resin is melted and the non-oriented polyester extruded and formed into a sheet shape is stretched in the longitudinal direction by utilizing the speed difference of the roll at a temperature equal to or higher than the glass transition temperature, and then stretched in the transverse direction by a tenter. The method of performing heat processing is mentioned.

  The polyester film of the present invention may be a uniaxially stretched film or a biaxially stretched film, but when the biaxially stretched film is used as a polarizer protective film, it may be observed from directly above the film surface. Although rainbow-like color spots are not seen, caution is necessary because rainbow-like color spots may be observed when observed from an oblique direction.

  This phenomenon is that a biaxially stretched film is composed of refractive index ellipsoids having different refractive indexes in the running direction, width direction, and thickness direction, and the retardation becomes zero depending on the light transmission direction inside the film (refractive index ellipse). This is because there is a direction in which the body appears to be a perfect circle. Therefore, when the liquid crystal display screen is observed from a specific oblique direction, a point where the retardation becomes zero may be generated, and a rainbow-like color spot is generated concentrically around that point. When the angle from the position directly above the film surface (normal direction) to the position where the rainbow-like color spots are visible is θ, the angle θ increases as the birefringence in the film increases, and the rainbow-like color increases. Spots are difficult to see. The biaxially stretched film tends to reduce the angle θ, and therefore the uniaxially stretched film is more preferable because rainbow-like color spots are less visible.

  However, a perfect uniaxial (uniaxial symmetry) film is not preferable because the mechanical strength in the direction orthogonal to the orientation direction is significantly reduced. The present invention has biaxiality (biaxial symmetry) in a range that does not substantially cause rainbow-like color spots or a range that does not cause rainbow-like color spots in a viewing angle range required for a liquid crystal display screen. It is preferable.

  The present inventors specify the ratio of the retardation of the protective film (in-plane retardation) and the retardation in the thickness direction (Rth) as a means to suppress the occurrence of rainbow spots while maintaining the mechanical strength of the protective film. It was found that control was performed so as to be within the range. Thickness direction retardation means an average of retardation obtained by multiplying two birefringences ΔNxz and ΔNyz by film thickness d when the film is viewed from the cross section in the thickness direction. The smaller the difference between the in-plane retardation and the thickness direction retardation, the more isotropic the birefringence action due to the observation angle, and the smaller the change in retardation due to the observation angle. Therefore, it is considered that rainbow-like color spots due to the observation angle are less likely to occur.

  The ratio of the retardation of the polyester film of the present invention to the retardation in the thickness direction (Re / Rth) is preferably 0.2 or more, more preferably 0.5 or more, and still more preferably 0.6 or more. As the ratio of the retardation to the retardation in the thickness direction (Re / Rth) is larger, the birefringence action is more isotropic, and the occurrence of iridescent color spots due to the observation angle is less likely to occur. In a complete uniaxial (uniaxial symmetry) film, the ratio of the retardation to the retardation in the thickness direction (Re / Rth) is 2. However, as described above, the mechanical strength in the direction orthogonal to the orientation direction is significantly lowered as the film approaches a complete uniaxial (uniaxial symmetry) film.

  On the other hand, the ratio of the retardation of the polyester film of the present invention to the retardation in the thickness direction (Re / Rth) is preferably 1.2 or less, more preferably 1.0 or less. In order to completely suppress the occurrence of rainbow-like color spots due to the observation angle, the ratio of retardation to thickness direction retardation (Re / Rth) does not have to be 2, and 1.2 or less is sufficient. Further, even when the ratio is 1.0 or less, it is possible to satisfy the viewing angle characteristics (about 180 ° left and right and about 120 ° up and down) required for the liquid crystal display device.

  Describing specifically the film forming conditions of the polyester film of the present invention, the longitudinal stretching temperature and the transverse stretching temperature are preferably from 80 to 130 ° C, particularly preferably from 90 to 120 ° C. The longitudinal draw ratio is preferably 1.0 to 3.5 times, particularly preferably 1.0 to 3.0 times. The transverse draw ratio is preferably 2.5 to 6.0 times, and particularly preferably 3.0 to 5.5 times. In order to control the retardation within the above range, it is preferable to control the ratio of the longitudinal draw ratio and the transverse draw ratio. If the difference between the vertical and horizontal draw ratios is too small, it is difficult to increase the retardation, which is not preferable. Also, setting the stretching temperature low is a preferable measure for increasing the retardation. In the subsequent heat treatment, the treatment temperature is preferably from 100 to 250 ° C, particularly preferably from 180 to 245 ° C.

In order to suppress retardation fluctuation, it is preferable that the thickness unevenness of the film is small.
Since the stretching temperature and the stretching ratio greatly affect the thickness variation of the film, it is necessary to optimize the film forming conditions from the viewpoint of the thickness variation. In particular, when the longitudinal draw ratio is lowered to increase the retardation, the value of the longitudinal thickness unevenness may be increased. Since there is a region in which the value of the vertical thickness unevenness becomes very high in a specific range of the draw ratio, it is desirable to set the film forming conditions outside this range.

The thickness unevenness of the film of the present invention is preferably 5.0% or less, more preferably 4.5% or less, still more preferably 4.0% or less, and 3.0% or less. It is particularly preferred. The thickness unevenness of the film can be measured by any means. For example, a tape-like sample (length 3 m) continuous in the film flow direction is collected, and an electronic micrometer (Millitron) manufactured by Seiko EM Co., Ltd. 1240) or the like is used to measure the thickness at 100 points at a pitch of 1 cm, and the maximum thickness (dmax), minimum value (dmin), and average value (d) are determined. %) Can be calculated.
Thickness unevenness (%) = ((dmax−dmin) / d) × 100

  As described above, the retardation of the film can be controlled within a specific range by appropriately setting the stretching ratio, the stretching temperature, and the film thickness. For example, it becomes easier to obtain a higher retardation as the stretching ratio between the longitudinal stretching and the lateral stretching is higher, the stretching temperature is lower, and the film is thicker. On the contrary, it becomes easier to obtain a lower retardation as the stretching ratio between the longitudinal stretching and the lateral stretching is lower, the stretching temperature is higher, and the film thickness is thinner. Moreover, the higher the stretching temperature and the lower the total stretching ratio, the easier it is to obtain a film having a lower ratio of retardation to thickness direction (Re / Rth). Conversely, the lower the stretching temperature and the higher the total stretching ratio, the easier it is to obtain a film with a higher ratio of retardation to thickness direction retardation (Re / Rth). The final film forming conditions must be set in consideration of the physical properties necessary for processing in addition to the retardation control.

  Although the thickness of the polyester film of this invention is arbitrary, the range of 15-300 micrometers is preferable, More preferably, it is the range of 15-200 micrometers. In principle, it is possible to obtain a retardation of 3000 nm or more even with a film having a thickness of less than 15 μm. However, in that case, the anisotropy of the mechanical properties of the film becomes remarkable, and it becomes easy to cause tearing, tearing, etc., and the practicality as an industrial material is remarkably lowered. A particularly preferable lower limit of the thickness is 25 μm. On the other hand, if the upper limit of the thickness of the 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. A particularly preferable upper limit of the thickness is 100 μm, which is about the same as a general TAC film. Polyethylene terephthalate is preferable as the polyester used as the film substrate in order to control the retardation within the range of the present invention even in the above thickness range.

  In addition, as a method of blending the ultraviolet absorber with the polyester film in the present invention, a known method can be used in combination. For example, a preliminarily kneaded extruder is used to blend the dried ultraviolet absorber and the polymer raw material. A master batch can be prepared and blended by, for example, a method of mixing the predetermined master batch and a polymer raw material during film formation. The added weight of the ultraviolet absorber added to the film is preferably 0.3 to 1.5%, more preferably 0.4 to 1.0%.

  At this time, the concentration of the UV absorber in the master batch is preferably 5 to 30% by mass in order to uniformly disperse the UV absorber and economically blend it. As a condition for producing the master batch, it is preferable to use a kneading extruder and to extrude it at a temperature not lower than the melting point of the polyester raw material and not higher than 290 ° C. for 1 to 15 minutes. Above 290 ° C, the weight loss of the UV absorber is large, and the viscosity of the master batch is greatly reduced. When the residence time is 1 minute or less, uniform mixing of the ultraviolet absorber becomes difficult. At this time, if necessary, a stabilizer, a color tone adjusting agent, and an antistatic agent may be added.

  In the present invention, it is preferable that the film has a multilayer structure of at least three layers and an ultraviolet absorber is added to the intermediate layer of the film. A film having a three-layer structure containing an ultraviolet absorber in the intermediate layer can be specifically produced as follows. Polyester pellets alone for the outer layer, master batches containing UV absorbers for the intermediate layer and polyester pellets are mixed at a predetermined ratio, dried, and then supplied to a known melt laminating extruder, which is slit-shaped. Extruded into a sheet form from a die and cooled and solidified on a casting roll to make an unstretched film. That is, using two or more extruders, a three-layer manifold or a merge block (for example, a merge block having a square merge portion), a film layer constituting both outer layers and a film layer constituting an intermediate layer are laminated. Then, a three-layer sheet is extruded from the die and cooled with a casting roll to form an unstretched film. In the present invention, it is preferable to perform high-precision filtration during 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 the molten resin is preferably 15 μm or less. When the filter particle size of the filter medium exceeds 15 μm, removal of foreign matters of 20 μm or more tends to be insufficient.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, and is implemented with appropriate modifications within a range that can be adapted to the gist of the present invention. These are all included in the technical scope of the present invention. In addition, the evaluation method of the physical property in the following examples is as follows.

(1) Retardation (Re)
Retardation is a parameter defined by the product (ΔNxy × d) of the biaxial refractive index anisotropy (ΔNxy = | Nx−Ny |) and the film thickness d (nm) on the film. Yes, it is a scale showing optical isotropy and anisotropy. The biaxial refractive index anisotropy (ΔNxy) was determined by the following method. Using two polarizing plates, the orientation axis direction of the film was determined, and a 4 cm × 2 cm rectangle was cut out so that the orientation axis directions were perpendicular to each other, and used as a measurement sample. With respect to this sample, the biaxial refractive index (Nx, Ny) perpendicular to each other and the refractive index (Nz) in the thickness direction were determined by an Abbe refractometer (NAGO-4T, measurement wavelength 589 nm, manufactured by Atago Co., Ltd.). The absolute value (| Nx−Ny |) of the refractive index difference between the axes was defined as the refractive index anisotropy (ΔNxy). The thickness d (nm) of the film was measured using an electric micrometer (manufactured by Fine Reef, Millitron 1245D), and the unit was converted to nm. Retardation (Re) was determined from the product (ΔNxy × d) of refractive index anisotropy (ΔNxy) and film thickness d (nm).

(2) Thickness direction retardation (Rth)
Thickness direction retardation is obtained by multiplying two birefringences ΔNxz (= | Nx−Nz |) and ΔNyz (= | Ny−Nz |) by film thickness d when viewed from the cross section in the film thickness direction. It is a parameter which shows the average of retardation obtained. Thickness direction retardation (Rth) is obtained by calculating Nx, Ny, Nz and film thickness d (nm) in the same manner as the measurement of retardation, and calculating the average value of (ΔNxz × d) and (ΔNyz × d). )

(3) Light transmittance at a wavelength of 380 nm Using a spectrophotometer (manufactured by Hitachi, U-3500 type), the light transmittance in the wavelength region of 300 to 500 nm of each film is measured using the air layer as a standard, and the light beam at a wavelength of 380 nm. The transmittance was determined.

(4) Observation of rainbow spots A polyester film prepared by the method described later is attached to one side of a polarizer made of PVA and iodine so that the absorption axis of the polarizer and the orientation main axis of the film are perpendicular to each other, and TAC is attached to the opposite surface. A polarizing plate was prepared by attaching a film (manufactured by FUJIFILM Corporation, thickness 80 μm).
The resulting polarizing plate is made of polyester on the outgoing light side of a liquid crystal display device using a white LED composed of a light emitting element in which a blue light emitting diode and a yttrium / aluminum / garnet yellow phosphor are combined as a light source (Nichia Chemical, NSPW500CS). The film was installed so as to be on the viewing side (or the emission light side). This liquid crystal display device has a polarizing plate having two TAC films as polarizer protective films on the incident light side of the liquid crystal cell. Visual observation was performed from the front side and the oblique direction of the polarizing plate of the liquid crystal display device, and the presence or absence of the occurrence of iridescence was determined as follows. In Comparative Example 3, a backlight light source using a cold cathode tube as a light source instead of the white LED was used.
◎: No rainbow spots from any direction.
○: When observed from an oblique direction, a partly extremely thin rainbow can be observed.
X: When observing from an oblique direction, rainbow spots can be clearly observed.

(5) Tear strength The tear strength of each film was measured in accordance with JIS P-8116 using an Elmendorf tear tester manufactured by Toyo Seiki Seisakusho. The tearing direction was performed so as to be parallel to the orientation main axis direction of the film, and was determined as follows. In addition, the measurement of the orientation axis direction was measured with a molecular orientation meter (manufactured by Oji Scientific Instruments, MOA-6004 type molecular orientation meter).
○: Tear strength is 50 mN or more ×: Tear strength is less than 50 mN

(6) Glass transition temperature Based on JIS K7121, using a differential scanning calorimeter (Seiko Instruments Co., Ltd., DSC6200), the temperature was raised at a rate of 20 ° C / min over a temperature range of 25 to 300 ° C, and from the DSC curve The obtained extrapolated glass transition start temperature was defined as the glass transition temperature.

(7) Adhesiveness A hard coat laminated polarizer protective film is determined in accordance with the description in 8.5.1 of JIS-K5400, and the adhesiveness between the hard coat layer and the substrate film is determined.

Specifically, 100 grid-like cuts that penetrate the hard coat layer and reach the base film are made on the hard coat layer surface using a cutter guide having a gap interval of 2 mm. Next, a cellophane adhesive tape (manufactured by Nichiban Co., Ltd., No. 405; 24 mm width) is attached to the grid-shaped cut surface and rubbed with an eraser to be completely attached. Then, the cellophane adhesive tape is peeled off from the hard coat layer surface of the hard coat laminated polarizer protective film vertically, and the number of squares peeled off from the hard coat layer surface of the hard coat laminate polarizer protective film is visually counted, and the following formula From the above, the adhesion between the hard coat layer and the substrate film is determined. In addition, what has peeled partially among squares is counted as a square which peeled.
Adhesiveness (%) = (1−number of peeled squares / 100) × 100

(8) Moisture and heat resistance The hard coat laminated polarizer protective film is allowed to stand in an environment of 60 ° C. and 95 RH% for 500 hours in a high-temperature and high humidity tank, and then the hard coat laminated polarizer protective film is taken out at room temperature. Left for hours. Thereafter, the adhesion between the hard coat layer and the substrate film was determined in the same manner as in (7) above, and ranked according to the following criteria.
A: 100%
○: 96% or more and less than 100% △: 80% or more and less than 96% ×: less than 80%

(9) Interference fringe improvement (iris color)
The hard coat laminated polarizer protective film was cut into an area of 10 cm (film width direction) × 15 cm (film longitudinal direction) to prepare a sample film. A black glossy tape (manufactured by Nitto Denko Corporation, vinyl tape No. 21; black) was bonded to the surface opposite to the hard coat layer surface of the obtained sample film. With the hard coat surface of the sample film as the top surface, the positional relationship where the reflection is the strongest visually observed from diagonally above using a three-wavelength daylight white color (National Palook, FL 15EX-N 15W) as a light source (distance 40 to distance from the light source) (60 cm, angle of 15 to 45 °).

The results of visual observation are ranked according to the following criteria. The observation is performed by five people who are familiar with the evaluation, and the highest rank is the evaluation rank. If two ranks have the same number, the center of the rank divided into three is adopted. For example, ◎ and ○ are 2 people each and △ is 1 person, ○ is ◎, ◎ is 1 person and ○ and △ are 2 people each, ○, ◎ and △ are 2 people each and ○ is 1 In the case of names, ○ is adopted.
◎: Iridescent colors are not observed even when observed from all angles. ○: Some iris colors are observed at some angles. △: Slightly iris colors are observed. X: Clear iris colors are observed. Be done

(Production Example 1-Polyester A)
When the temperature of the esterification reactor was raised to 200 ° C., 86.4 parts by mass of terephthalic acid and 64.6 parts by mass of ethylene glycol were charged and 0.017 parts by mass of antimony trioxide as a catalyst while stirring. 0.064 parts by mass of magnesium acetate tetrahydrate and 0.16 parts by mass of triethylamine were charged. Subsequently, the pressure was raised and the esterification reaction was performed under the conditions of a gauge pressure of 0.34 MPa and 240 ° C., and then the esterification reaction vessel was returned to normal pressure, and 0.014 parts by mass of phosphoric acid was added. Furthermore, it heated up to 260 degreeC over 15 minutes, and 0.012 mass part of trimethyl phosphate was added. Then, 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 reaction can and subjected to polycondensation reaction at 280 ° C. under reduced pressure.

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

(Production Example 2-Polyester B)
10 parts by weight of a dried UV absorber (2,2 ′-(1,4-phenylene) bis (4H-3,1-benzoxazinon-4-one), PET (A) containing no particles (inherent viscosity Was 0.62 dl / g) and 90 parts by mass were mixed, and a polyethylene terephthalate resin (B) containing an ultraviolet absorber was obtained using a kneading extruder (hereinafter abbreviated as PET (B)).

(Production Example 3-Preparation of coating solution for easily bonding layer formation with polarizer)
A transesterification reaction and a polycondensation reaction are carried out by a conventional method, and as a dicarboxylic acid component (based on the whole dicarboxylic acid component) 46 mol% terephthalic acid, 46 mol% isophthalic acid and 8 mol% sodium 5-sulfonatoisophthalate, A water-dispersible sulfonic acid metal base-containing copolymer polyester resin having a composition of 50 mol% ethylene glycol and 50 mol% neopentyl glycol as a glycol component (based on the entire glycol component) was prepared. Next, 51.4 parts by mass of water, 38 parts by mass of isopropyl alcohol, 5 parts by mass of n-butyl cellosolve, 0.06 parts by mass of nonionic surfactant were mixed and then heated and stirred. After adding 5 parts by mass of a water-dispersible sulfonic acid metal base-containing copolymer polyester resin and continuing to stir until the resin is no longer agglomerated, the resin water dispersion is cooled to room temperature to obtain a solid content concentration of 5.0% by mass. A uniform water-dispersible copolymerized polyester resin liquid was obtained. Furthermore, after dispersing 3 parts by mass of aggregated silica particles (Silicia 310, manufactured by Fuji Silysia Co., Ltd.) in 50 parts by mass of water, 99.46 parts by mass of the water-dispersible copolyester resin solution was mixed with 99.46 parts by mass of the silicia 310. 0.54 parts by mass of an aqueous dispersion was added, and 20 parts by mass of water was added with stirring to obtain a coating solution for forming an easily adhesive layer with a polarizer.

(Production Example 4-Production of polyester resin for coating layer)
In a stainless steel autoclave equipped with a stirrer, a thermometer, and a partial reflux condenser, 186 parts by mass of dimethyl terephthalate, 186 parts by mass of dimethyl isophthalate, 23.7 parts of dimethyl 5-sodium sulfoisophthalate, 137 of neopentyl glycol Mass parts, 191 parts by mass of ethylene glycol, and 0.5 parts by mass of tetra-n-butyl titanate were charged, and a transesterification reaction was performed from 160 ° C. to 220 ° C. over 4 hours. Next, the temperature was raised to 255 ° C., and the pressure of the reaction system was gradually reduced, followed by reaction for 1 hour 30 minutes under a reduced pressure of 29 Pa to obtain a copolymerized polyester resin (A-1). The obtained copolyester resin was light yellow and transparent.

  In the same manner, copolymer polyester resins (A-2, A-3, A-4) having different compositions were obtained. Table 1 shows the results of the composition and weight average molecular weight measured by NMR for these copolyester resins.

(Production Example 5-Production of polyester resin dispersion for coating layer and coating solution)
In a reactor equipped with a stirrer, a thermometer and a reflux device, 20 parts by mass of the polyester resin (A-1) produced above and 15 parts by mass of ethylene glycol monobutyl ether are added and heated and stirred at 100 ° C. Dissolved. After the resin was completely dissolved, 65 parts by mass of water was gradually added to the polyester solution while stirring. After the addition, the solution was cooled to room temperature while stirring to prepare an aqueous dispersion (B-1) of milky white polyester having a solid content of 20% by mass. Similarly, using the polyester resins (A-2) to (A-4) instead of the polyester resin (A-1), an aqueous dispersion was prepared, and the aqueous dispersions (B-2) to (B-) were respectively obtained. 4).

  40 parts by mass of the obtained polyester aqueous dispersion (B-1), 18 parts by mass of a 44% by mass solution of hydroxybis (lactato) titanium (manufactured by Matsumoto Pharmaceutical Co., Ltd., TC310), 150 parts by mass of water and 100 parts by mass of isopropyl alcohol 1 part by mass of anionic surfactant (Naopelex No6F powder, manufactured by Kao Corporation), colloidal silica fine particles (catalyst chemical industry, Cataloid SI80P; average particle size 80 nm) An aqueous dispersion was added in an amount of 2% by mass as silica with respect to the resin solid content to prepare a coating solution (hereinafter abbreviated as coating solution (C-1)).

Example 1
After drying 90 parts by mass of PET (A) resin pellets containing no particles as a raw material for the base film intermediate layer and 10 parts by mass of PET (B) resin pellets containing an ultraviolet absorber at 135 ° C. for 6 hours under reduced pressure (1 Torr) , And supplied to the extruder 2 (for the intermediate layer II layer). Also, the PET (A) was dried by an ordinary method and supplied to the extruder 1 (for the outer layer I layer and the outer layer III), and dissolved at 285 ° C. . After filtering these two kinds of polymers with a filter medium made of a sintered stainless steel (nominal filtration accuracy of 10 μm particles 95% cut), laminating them in a two-kind / three-layer confluence block, and extruding them into a sheet form from a die, The film was wound around a casting drum having a surface temperature of 30 ° C. using an electrostatic application casting method, and then cooled and solidified to produce an unstretched film. At this time, the discharge amount of each extruder was adjusted so that the thickness ratio of the I layer, the II layer, and the III layer was 10:80:10.

Next, the reverse roll method is used to easily adhere to both surfaces of the unstretched PET film so that one side is a coating solution for forming an easy-adhesion layer with the polarizer and the other side is the coating solution (C-1). The coating layer was applied and dried at 80 ° C. for 20 seconds. In addition, it adjusted so that the application quantity after the last (after extending | stretching) drying might be set to 0.15 g / m < ² >.

  The unstretched film on which this easy-adhesion layer was formed was guided to a tenter stretching machine, guided to a hot air zone at a temperature of 125 ° C. while being gripped by a clip, and stretched 4.0 times in the width direction. After drying, a polarizer that is a uniaxially oriented PET film with a film thickness of about 50 μm is processed with a temperature of 225 ° C. for 30 seconds while maintaining the width stretched in the width direction, and further with a 3% relaxation treatment in the width direction. A protective film was obtained.

On the coated surface formed with the obtained polarizer protective film coating solution (C-1), 5 parts by mass of methyl ethyl ketone and 5 parts by mass of hard coat agent (manufactured by Dainichi Seika, Seika Beam EXF01 (B); solid content: 100% by mass) The solution with the added portion was applied using a # 8 wire bar and dried at 70 ° C. for 1 minute to remove the solvent. Next, the hard coat layer surface was irradiated with ultraviolet rays under the conditions of irradiation energy of 200 mJ / cm ² and irradiation distance of 15 cm using a high pressure mercury lamp while the film coated with the hard coat layer was run at a feeding speed of 5 m / min. A hard coat laminated polarizer protective film having a hard coat layer of 3 μm was obtained. The evaluation results are shown in Table 2.

(Example 2)
A polarizer protective film, which is a uniaxially oriented PET film, was obtained in the same manner as in Example 1 except that the thickness of the unstretched film was changed to about 100 μm. A hard coat layer was provided on the obtained polarizer protective film in the same manner as in Example 1 to obtain a hard coat laminated polarizer protective film. The evaluation results are shown in Table 2.

(Example 3)
An unstretched film produced by the same method as in Example 1 is heated to 105 ° C. using a heated roll group and an infrared heater, and then stretched 1.5 times in the running direction with a roll group having a difference in peripheral speed. After that, the film was stretched 4.0 times in the width direction in the same manner as in Example 1 to obtain a polarizer protective film which is a biaxially oriented PET film having a film thickness of about 50 μm. A hard coat layer was provided on the obtained polarizer protective film in the same manner as in Example 1 to obtain a hard coat laminated polarizer protective film. The evaluation results are shown in Table 2.

Example 4
In the same manner as in Example 3, the film was stretched 2.0 times in the running direction and 4.0 times in the width direction to obtain a polarizer protective film which is a biaxially oriented PET film having a film thickness of about 50 μm. A hard coat layer was provided on the obtained polarizer protective film in the same manner as in Example 1 to obtain a hard coat laminated polarizer protective film. The evaluation results are shown in Table 2.

(Example 5)
In the same manner as in Example 3, the film was stretched 3.3 times in the running direction and 4.0 times in the width direction to obtain a polarizer protective film which is a biaxially oriented PET film having a film thickness of about 75 μm. A hard coat layer was provided on the obtained polarizer protective film in the same manner as in Example 1 to obtain a hard coat laminated polarizer protective film. The evaluation results are shown in Table 2.

(Example 6)
A polarizer protective film, which is a uniaxially oriented PET film having a film thickness of 50 μm, was obtained in the same manner as in Example 1 without using a PET resin (B) containing an ultraviolet absorber in the intermediate layer. Although the resulting film was free from iridescent color spots, it has a high light transmittance of 380 nm, and there is a concern of deteriorating the optical functional dye. A hard coat layer was provided on the obtained polarizer protective film in the same manner as in Example 1 to obtain a hard coat laminated polarizer protective film. The evaluation results are shown in Table 2.

(Example 7)
In the same manner as in Example 3, the film was stretched 4.0 times in the running direction and 1.0 times in the width direction to obtain a polarizer protective film which is a uniaxially oriented PET film having a film thickness of about 100 μm. The obtained film had Re of 3000 nm or more and good visibility, but the mechanical strength was slightly inferior. A hard coat layer was provided on the obtained polarizer protective film in the same manner as in Example 1 to obtain a hard coat laminated polarizer protective film. The evaluation results are shown in Table 2.

(Example 8)
In the same manner as in Example 3, the film was stretched 3.5 times in the running direction and 3.7 times in the width direction to obtain a polarizer protective film which is a biaxially oriented PET film having a film thickness of about 250 μm. The obtained film had Re of 4500 nm or more, but the Re / Rth ratio was less than 0.2. Therefore, an extremely thin rainbow was observed in an oblique direction. A hard coat layer was provided on the obtained polarizer protective film in the same manner as in Example 1 to obtain a hard coat laminated polarizer protective film. The evaluation results are shown in Table 2.

Example 9
In the same manner as in Example 1, the film was stretched 1.0 times in the running direction and 3.5 times in the width direction to obtain a polarizer protective film which is a uniaxially oriented PET film having a film thickness of about 75 μm. A hard coat layer was provided on the obtained polarizer protective film in the same manner as in Example 1 to obtain a hard coat laminated polarizer protective film. The evaluation results are shown in Table 2.

(Example 10)
A polarizer protective film, which is a uniaxially oriented PET film having a thickness of about 275 μm, was obtained by using the same method as in Example 1 and changing the thickness of the unstretched film. A hard coat layer was provided on the obtained polarizer protective film in the same manner as in Example 1 to obtain a hard coat laminated polarizer protective film. The evaluation results are shown in Table 2.

(Example 11)
48 parts by mass of polyester aqueous dispersion (B-2), 44 parts by mass of hydroxybis (lactato) titanium (manufactured by Matsumoto Pharmaceutical Co., Ltd., TC310) 15 parts by mass, 150 parts by mass of water and 100 parts by mass of isopropyl alcohol Further, an anionic surfactant (Kao Co., Ltd., Neopelex No6F powder) is added in an amount of 1% by mass with respect to the coating solution, colloidal silica fine particles (catalyst chemical industry, Cataloid SI80P; average particle size 80 nm) in water dispersion. Was added in an amount of 2% by mass as silica with respect to the resin solid content to prepare a coating solution (hereinafter abbreviated as coating solution (C-2)). A polarizer protective film, which is a uniaxially oriented PET film having a coating layer, was obtained in the same manner as in Example 1 except that this coating solution (C-2) was used. A hard coat layer was provided on the obtained polarizer protective film in the same manner as in Example 1 to obtain a hard coat laminated polarizer protective film. The evaluation results are shown in Table 2.

(Example 12)
Polyester aqueous dispersion (B-3) 12 parts by mass, diisopropoxybis (triethanolaminato) titanium 80% by mass solution (manufactured by Matsumoto Pharmaceutical Co., Ltd., TC400) 17 parts by mass, water 150 parts by mass and isopropyl alcohol 100 parts by mass were mixed, and anionic surfactant (Neopelex No6F powder, manufactured by Kao Corporation) was 1% by mass with respect to the coating liquid, colloidal silica fine particles (catalyst chemical industry, Cataloid SI80P; average particle size) 80 nm) An aqueous dispersion was added in an amount of 2% by mass as silica with respect to the resin solid content to prepare a coating solution (hereinafter abbreviated as coating solution (C-3)). A polarizer protective film, which is a uniaxially oriented PET film having a coating layer, was obtained in the same manner as in Example 1 except that this coating solution (C-3) was used. A hard coat layer was provided on the obtained polarizer protective film in the same manner as in Example 1 to obtain a hard coat laminated polarizer protective film. The evaluation results are shown in Table 2.

(Example 13)
24 parts by weight of polyester aqueous dispersion (B-4), 11 parts by weight of diisopropoxybis (acetylacetonate) titanium, 150 parts by weight of water and 100 parts by weight of isopropyl alcohol were mixed, respectively, and an anionic surfactant ( 1% by mass of Neoperex No6F powder made by Kao Corporation and 2% by weight of colloidal silica fine particles (catalyst chemical industry, Cataloid SI80P; average particle size of 80 nm) as a silica with respect to the resin solid content. % Was added to prepare a coating solution (hereinafter abbreviated as coating solution (C-4)). A polarizer protective film, which is a uniaxially oriented PET film having a coating layer, was obtained in the same manner as in Example 1 except that this coating solution (C-4) was used. A hard coat layer was provided on the obtained polarizer protective film in the same manner as in Example 1 to obtain a hard coat laminated polarizer protective film. The evaluation results are shown in Table 2.

(Example 14)
32 parts by mass of a polyester aqueous dispersion (B-4), 10 parts by mass of zirconium acetate, 150 parts by mass of water and 100 parts by mass of isopropyl alcohol were mixed, and an anionic surfactant (Neopelex No6F powder manufactured by Kao Corporation) was mixed. ) 1% by mass with respect to the coating solution, and 2% by mass of colloidal silica fine particles (catalyst chemical industry, Cataloid SI80P; average particle size 80 nm) aqueous dispersion as silica with respect to the resin solid content was prepared to prepare a coating solution. (Hereinafter abbreviated as coating solution (C-5)). A polarizer protective film, which is a uniaxially oriented PET film having a coating layer, was obtained in the same manner as in Example 1 except that this coating solution (C-5) was used. A hard coat layer was provided on the obtained polarizer protective film in the same manner as in Example 1 to obtain a hard coat laminated polarizer protective film. The evaluation results are shown in Table 2.

(Example 15)
Except that the light source of the liquid crystal display device was an organic light emitting diode (OLED), and rainbow spots were observed, and the evaluation was performed by adding particles to the hard coat layer to make the surface uneven and changing it to an antiglare layer. Was the same as in Example 1.

(Comparative Example 1)
In the same manner as in Example 3, the film was stretched 3.6 times in the running direction and 4.0 times in the width direction to obtain a polarizer protective film which is a biaxially oriented PET film having a film thickness of about 38 μm. The obtained film had low retardation, and rainbow-like color spots were observed when observed from an oblique direction. A hard coat layer was provided on the obtained polarizer protective film in the same manner as in Example 1 to obtain a hard coat laminated polarizer protective film. The evaluation results are shown in Table 2.

(Comparative Example 2)
A polarizer protective film, which is a uniaxially oriented PET film having a thickness of about 10 μm, was obtained by using the same method as in Example 1 and changing the thickness of the unstretched film. Since the obtained film was very easy to tear and there was no stiffness, it could not be used as a polarizer protective film. Moreover, the retardation was low and iridescent colored spots were observed. A hard coat layer was provided on the obtained polarizer protective film in the same manner as in Example 1 to obtain a hard coat laminated polarizer protective film. The evaluation results are shown in Table 2.

(Comparative Example 3)
The same procedure as in Example 1 was performed except that rainbow spots were observed using a cold cathode tube as the light source of the liquid crystal display device. A hard coat layer was provided on the obtained polarizer protective film in the same manner as in Example 1 to obtain a hard coat laminated polarizer protective film. The evaluation results are shown in Table 2.

(Comparative Example 4)
80 parts by mass of polyester aqueous dispersion (B-1), 150 parts by mass of water and 100 parts by mass of isopropyl alcohol are mixed, and an anionic surfactant (Naopelex No6F powder, manufactured by Kao Corporation) is used as a coating liquid. On the other hand, 1% by mass of colloidal silica fine particles (catalyst chemical industry, Cataloid SI80P; average particle size of 80 nm) was added in an amount of 2% by mass as silica with respect to the resin solids to prepare a coating solution (hereinafter referred to as coating solution ( Abbreviated as C-6)). A polarizer protective film, which is a uniaxially oriented PET film having a coating layer, was obtained in the same manner as in Example 1 except that this coating solution (C-6) was used. A hard coat layer was provided on the obtained polarizer protective film in the same manner as in Example 1 to obtain a hard coat laminated polarizer protective film. The evaluation results are shown in Table 2.

(Comparative Example 5)
64 parts by mass of an aqueous polyester dispersion (B-1), 10 parts by mass of a self-crosslinking polyurethane resin having a blocked isocyanate group (Daiichi Kogyo Seiyaku Co., Ltd., Elastron H-3), an elastron catalyst (Daiichi Kogyo Seiyaku, Cat 64) ) 1 part by mass, further 1% by weight of anionic surfactant (Naopelex No6F powder, manufactured by Kao Corporation), and colloidal silica fine particles (catalyst chemical industry, Cataloid SI80P; average particle size 80 nm) water The dispersion was added in an amount of 2% by mass as silica with respect to the resin solids to prepare a coating solution (hereinafter abbreviated as coating solution (C-7)). Except having used this coating liquid (C-7), it carried out similarly to Example 1, and obtained the polarizer protective film which is a uniaxially oriented PET film which has a coating layer. A hard coat layer was provided on the obtained polarizer protective film in the same manner as in Example 1 to obtain a hard coat laminated polarizer protective film. The evaluation results are shown in Table 2.

(Comparative Example 6)
A 44% by mass solution of hydroxybis (lactato) titanium (manufactured by Matsumoto Pharmaceutical Co., Ltd., TC310) 40 parts by mass, 150 parts by mass of water and 100 parts by mass of isopropyl alcohol were mixed, respectively, and an anionic surfactant (Kao Corporation) 1% by mass of Neoperex No6F powder) and 2% by mass of colloidal silica fine particles (catalyst SI 80P; average particle size 80 nm) in water dispersion as silica with respect to the resin solids. Then, a coating solution was prepared (hereinafter abbreviated as coating solution (C-8)). A polarizer protective film, which is a uniaxially oriented PET film having a coating layer, was obtained in the same manner as in Example 1 except that this coating solution (C-8) was used. A hard coat layer was provided on the obtained polarizer protective film in the same manner as in Example 1 to obtain a hard coat laminated polarizer protective film. The evaluation results are shown in Table 2.

(Comparative Example 7)
32 parts by mass of a polyester aqueous dispersion (B-2), 5 parts by mass of a self-crosslinking polyurethane resin having a blocked isocyanate group (Daiichi Kogyo Seiyaku Co., Ltd., Elastoron H-3), an elastotron catalyst (Daiichi Kogyo Seiyaku Co., Ltd., Cat 64) ) 0.5 parts by weight, niobium oxide 10% by weight aqueous solution (manufactured by Taki Chemical Co., Ltd., SAM-0) 64 parts by weight, and further an anionic surfactant (Kao Corporation, Neopelex No6F powder). 1% by mass with respect to the liquid, and 2% by mass of an aqueous dispersion of colloidal silica fine particles (catalyst SI 80P; average particle size of 80 nm) as a silica with respect to the solid content of the resin was added to prepare a coating liquid (hereinafter referred to as coating). Liquid (C-9)). Except having used this coating liquid (C-9), it carried out similarly to Example 1, and obtained the polarizer protective film which is a uniaxially oriented PET film which has a coating layer. A hard coat layer was provided on the obtained polarizer protective film in the same manner as in Example 1 to obtain a hard coat laminated polarizer protective film. The evaluation results are shown in Table 2.

(Comparative Example 8)
Acrylic resin emulsion having a solid content of 20% by mass (methyl methacrylate / ethyl acrylate / acrylic acid / N-methylolacrylamide = 60/40/2/4; mass ratio), 80 parts by mass, di-n-butoxybis (triethanolaminato) ) 3.2 parts by weight of titanium, 150 parts by weight of water and 100 parts by weight of isopropyl alcohol were mixed, and an anionic surfactant (Naopelex No6F powder, manufactured by Kao Corporation) was added in an amount of 1% by weight, respectively. Colloidal silica fine particles (Catalyst Kasei Kogyo Co., Ltd., Cataloid SI80P; average particle size 80 nm) aqueous dispersion was added in an amount of 2% by mass as silica to the resin solids to prepare a coating solution (hereinafter referred to as coating solution (C-10)). Abbreviated). A polarizer protective film, which is a uniaxially oriented PET film having a coating layer, was obtained in the same manner as in Example 1 except that this coating solution (C-10) was used. The obtained polarizer protective film was provided with a hard coat layer in the same manner as in Example 1 to obtain a hard coat laminated polarizer protective film. The evaluation results are shown in Table 2.

(Comparative Example 9)
Acrylic resin emulsion having a solid content of 20% by mass (methyl methacrylate / ethyl acrylate / acrylic acid / N-methylolacrylamide = 25/75/4/2: mass ratio) 48 parts by mass, titanium-modified aqueous resin (Matsumoto Pharmaceutical Co., Ltd.) 6.4 parts by mass, ORGATICS WS680), 150 parts by mass of water and 100 parts by mass of isopropyl alcohol are mixed, and an anionic surfactant (manufactured by Kao Corporation, Neopelex No6F powder) is added to the coating solution. 1% by mass, colloidal silica fine particles (catalyst chemical industry, Cataloid SI80P; average particle size 80 nm) in water dispersion was added in an amount of 2% by mass as silica with respect to the resin solids to prepare a coating solution (hereinafter referred to as coating solution (C -11)). A polarizer protective film, which is a uniaxially oriented PET film having a coating layer, was obtained in the same manner as in Example 1 except that this coating solution (C-11) was used. The obtained polarizer protective film was provided with a hard coat layer in the same manner as in Example 1 to obtain a hard coat laminated polarizer protective film. The evaluation results are shown in Table 2.

(Comparative Example 10)
A polarizer protective film, which is an uncoated uniaxially oriented PET film, was obtained in the same manner as in Example 1 except that the coating layer forming coating solution was not used. A hard coat layer was provided on one side of the polarizer protective film in the same manner as in Example 1 to obtain a hard coat laminated polarizer protective film. The evaluation results are shown in Table 2.

(Comparative Example 11)
10 parts by mass of titanium oxide ultrafine particles (Ishihara Sangyo, TTO-S-1) having a particle diameter (width / length) of 0.01-0.02 μm / 0.05-0.1 μm as observed with an electron microscope 90 parts by mass of water was added to the mixture, and dispersed at 5000 rpm for 30 minutes with a disperser (AUTO CELL MASTER CM-200) to prepare an aqueous dispersion A of titanium oxide particles having a concentration of 10% by mass. Next, 30 parts by mass of a polyester aqueous dispersion (B-4), 150 parts by mass of water and 100 parts by mass of isopropyl alcohol are mixed, and an anionic surfactant (Neopelex No6F powder manufactured by Kao Corporation) is further applied as a coating solution. The polyester aqueous dispersion B was prepared by adding 1% by mass with respect to the aqueous solution. 30 parts by mass of the aqueous dispersion A of titanium oxide particles prepared as described above was added to the aqueous dispersion B of polyester to prepare a coating solution. However, since the titanium oxide fine particles became a gel and settled in the coating solution, application to the base film was stopped.

Table 2 below shows the results measured for the above examples and comparative examples.

Claims (11)

A group consisting of an aqueous polyester resin (A) and a water-soluble titanium chelate compound, a water-soluble titanium acylate compound, a water-soluble zirconium chelate compound, and a water-soluble zirconium acylate compound on at least one side of a polyester film having a retardation of 3000 to 30000 nm. A polarizing plate in which a polarizer protective film in which a coating layer formed from an aqueous coating solution mainly comprising one or more selected from (B) is laminated is laminated on at least one side of the polarizer, and continuous A liquid crystal display device including a white light source having a typical emission spectrum. The liquid crystal display device according to claim 1, wherein a mixing ratio (A / B) of the (A) and (B) is 10/90 to 95/5 in terms of mass. The aqueous polyester resin (A) is a copolymerized polyester resin containing 1 to 10 mol% of an aromatic dicarboxylic acid component containing a sulfonic acid metal base with respect to the total dicarboxylic acid component of the polyester. Liquid crystal display device. The liquid crystal display device in any one of Claims 1-3 whose glass transition temperature of water-based polyester resin (A) is 40 degreeC or more. The liquid crystal display device according to claim 1, wherein a ratio of the retardation of the polyester film to the retardation in the thickness direction (Re / Rth) is 0.2 or more. The liquid crystal display device according to any one of claims 1 to 5, wherein the polyester film comprises three or more layers, an ultraviolet absorber is contained in a layer other than the outermost layer, and the light transmittance at 380 nm is 20% or less. The liquid crystal display device according to claim 1, wherein a hard coat layer made of an electron beam, an ultraviolet curable acrylic resin, or a siloxane-based thermosetting resin is further laminated on the coating layer. The coating layer has one or more layers selected from the group consisting of an antiglare layer, an antireflection layer, a low reflection layer, a low reflection antiglare layer, an antireflection antiglare layer, and an antistatic layer. 8. A liquid crystal display device according to any one of 7 above. The liquid crystal display device according to claim 1, wherein the polarizer protective film is laminated on the polarizer via an ultraviolet curable, electron beam curable, or thermosetting adhesive. The liquid crystal display device according to claim 1 , wherein the polarizing plate is disposed on an emission light side with respect to the liquid crystal. The liquid crystal display device according to claim 1, wherein the white light source having the continuous emission spectrum is a white light emitting diode.