Polarizing plate protective film

Abstract

The present invention addresses the problem of providing a polarizing plate protective film containing a resin and a pigment compound, the polarizing plate protective film being capable of protecting a display element from outside light and not causing light emission loss with respect to light emission by the display element when used in a display device and in particular in an organic electroluminescence display device, and the polarizing plate protective film additionally being free from bleed out and having excellent lightfastness.　A polarizing plate protective film according to the present invention is characterized by containing a compound that has a structure represented by formula 1.

Description

[Technical Field]

[0001] The present invention relates to a polarizing plate protective film. More specifically, the present invention relates to a polarizing plate protective film containing a resin and a dye compound, which, when used in a display device, particularly an organic electroluminescent display device, can protect the display element from ambient light, does not cause light emission loss to the display element, does not bleed out, and has excellent light resistance. [Background technology]

[0002] Generally, to impart the ability to cut light across a wide wavelength range, including ultraviolet light and short-wavelength visible light, to optical films such as polarizer protective films, methods include adding ultraviolet absorbers to the substrate or providing them as a separate layer on the substrate. In such cases, high concentrations of ultraviolet absorbers may be used to cut short-wavelength visible light, or the concentration may be increased as the film becomes thinner. However, high concentrations can cause undesirable discoloration on the longer wavelength side, as well as whitening and precipitation (bleed-out). To solve these problems, there is a need for materials that can absorb (cut) short-wavelength visible light even at low concentrations.

[0003] On the other hand, in order to prevent light loss from occurring in the light emission of display elements used in organic electroluminescence (EL) display devices, it is necessary to ensure sufficient transmittance in the light emission region of the display element (wavelengths longer than 430 nm). Therefore, it is necessary to use materials that can suppress light absorption in this region and ensure sufficient light transmittance, and to use technology that suppresses degradation of the display element due to ambient light.

[0004] For example, Patent Document 1 discloses a technique for adjusting light absorption in a specific wavelength region by incorporating a photoselective absorption compound (such as a compound containing a merocyanine structure in its molecule) that possesses light absorption properties on the short wavelength side of visible light into a resin. However, there is no description regarding the light resistance of the photoselective absorption compound.

[0005] Patent Document 2 discloses a highly transparent optical film containing at least one light-absorbing material, such as a resin, an ultraviolet absorber, and a visible light-absorbing dye, which has a light transmittance of 10% or less at a wavelength of 380-410 nm and a light transmittance of 80% or more at a wavelength of 440 nm, does not exhibit bleed-out during film formation, and has excellent ultraviolet cut properties and sharp wavelength cut properties in the short wavelength region of visible light. However, similarly, there is no description regarding the light resistance of the ultraviolet absorber and the visible light-absorbing dye in the optical film containing the light-absorbing material.

[0006] Furthermore, Patent Document 3 discloses an optical film that contains a specific resin (a polymer containing an alicyclic structure) and an ultraviolet absorber, and also contains a dye compound capable of controlling the light transmittance of a specific wavelength, thereby protecting an image display device from ultraviolet light and improving the hue when the image display device is viewed from the front. However, there is no description regarding the durability of this optical film in terms of bleed-out, and there is a great need for improved durability as the film becomes thinner. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2019-8293 [Patent Document 2] Japanese Patent Publication No. 2017-187619 [Patent Document 3] International Publication No. 2020 / 158468 [Overview of the project] [Problems that the invention aims to solve]

[0008] The present invention has been made in view of the above problems and situations, and the problem to be solved is to provide a polarizing plate protective film containing a resin and a dye compound, which can protect a display element from external light when used in a display device, particularly an organic electroluminescence display device, and does not cause light emission loss with respect to the light emission of the display element, and has no bleed-out and excellent light resistance.

Means for Solving the Problems

[0009] In order to solve the above problems, the present inventor has found that by incorporating a compound having a specific structure shown below into a polarizing plate protective film in the process of examining the causes of the above problems, etc., the display element can be protected from external light, and there is no light emission loss with respect to the light emission of the display element, and there is no bleed-out, and a polarizing plate protective film containing a resin and a dye compound with excellent light resistance can be obtained.

[0010] That is, the above problems according to the present invention are solved by the following means.

[0011] 1. A polarizing plate protective film characterized by containing a compound having a structure represented by the following formula 1.

Chemical formula

Effects of the Invention

[0012] By the above means of the present invention, a polarizing plate protective film containing a resin and a dye compound can be provided, which can protect a display element from external light when used in a display device, particularly an organic electroluminescence display device, and does not cause light emission loss with respect to the light emission of the display element, and has no bleed-out and excellent light resistance.

[0013] Although the mechanism or action mechanism of the expression of the effects of the present invention is not clear, it is speculated as follows.

[0014] By adding a specific substituent structure to the benzotriazole skeleton, which is a compound having the structure represented by Formula 1, the hydrophobicity of the compound is increased. This hydrophobicity strengthens its interaction with resins and other additives, and this enhanced interaction suppresses the degradation of the compound by light, thereby improving its lightfastness (also called "photofastness"). Furthermore, the compound has good compatibility with the resin in terms of sp value (also called "solubility parameter"), and even when the amount necessary to form a desired absorption spectrum is added, it does not cause bleed-out or whitening, thus improving durability. [Brief explanation of the drawing]

[0015] [Figure 1] Cross-sectional view showing an example of the configuration of a polarizing plate 10A using the polarizing plate protective film of the present invention. [Figure 2] Cross-sectional view showing an example of the configuration of polarizing plate 10B, which is another aspect of the present invention. [Figure 3] Cross-sectional view showing an example configuration of an organic EL display device 20 using the polarizing plate protective film of the present invention. [Figure 4] A schematic diagram showing a method for manufacturing a thin-film polarizing plate protective film according to one embodiment of the present invention. [Figure 5] A schematic plan view showing the general configuration of a manufacturing apparatus for diagonally stretched film. [Figure 6] Figure 5 shows a schematic plan view illustrating an example of the rail pattern of the stretching section of the diagonally stretched film manufacturing apparatus. [Modes for carrying out the invention]

[0016] The polarizing plate protective film of the present invention is characterized by containing a compound having the structure represented by the above formula 1. This feature is a technical feature common to or corresponding to the following embodiments.

[0017] The present invention, its components, and embodiments and models for carrying out the present invention will be described in detail below. In this application, "~" is used to mean that the numerical values ​​before and after it are included as the lower limit and upper limit.

[0018] ≪Overview of the Polarizing Plate Protective Film of the Present Invention≫ The polarizing plate protective film of the present invention is characterized by containing a compound having a structure represented by the following formula 1.

[0019] [ka]

[0020] The structure of the polarizing plate protective film of the present invention will be described in detail below. In this invention, a compound having the structure represented by Formula 1 is referred to as a "dye compound".

[0021] [1] Polarizing plate configuration Figure 1 is a cross-sectional view showing a preferred configuration example of a polarizer 10A of the present invention, having a polarizer protective film 1, a polarizer layer 2, and a phase difference film 3 in that order from the viewing side. When the polarizer protective film 1, polarizer layer 2, and phase difference film 3 are laminated, it is preferable that they are bonded together by an adhesive layer or bonding agent (not shown). The phase difference film 3 refers to a polarizer protective film that adjusts the phase difference depending on the purpose of use of the polarizer.

[0022] In the present invention, it is preferable that the polarizing plate used has various functional layers in addition to the polarizing plate protective film 1, polarizer layer 2, and phase difference film 3. As shown in Figure 2, it is also preferable to arrange a hard coat layer 4 as an upper layer of the polarizing plate protective film 1 as a functional layer, from the viewpoint of improving the scratch resistance of the outermost surface when the polarizing plate is attached to a display device. It is also a preferred embodiment to have a polarizing plate 10B with an adhesive layer 5 having an adhesive function to adhere to the display device as a lower layer of the phase difference film.

[0023] In the present invention, for example, using polarizing plate 10A as an example, as shown in the cross-sectional view of the organic EL display device 20 in Figure 3, an adhesive layer 5 is arranged adjacent to the phase difference film 3 of the polarizing plate 10A and adhered to the viewing side surface of the organic EL element 11. This is a preferred configuration from the viewpoint of exhibiting the effects expected of the polarizing plate protective film 1 of the present invention.

[0024] [2] Dye compounds The dye compound according to the present invention (hereinafter also referred to as "compound (D)") is a compound having the structure represented by Formula 1.

[0025] The dye compound in question is a compound whose maximum absorption wavelength in the 300-460 nm wavelength range is located in the 365-430 nm wavelength range within its absorption spectrum.

[0026] (Measurement of maximum absorption wavelength) The maximum absorption wavelength of the above-mentioned compounds can be determined, for example, by measuring the absorption spectrum of the dye compound or ultraviolet absorber in chloroform using a UV-2450 ultraviolet-visible spectrophotometer manufactured by Shimadzu Corporation.

[0027] In this invention, "maximum absorption wavelength" refers to the wavelength (nm) that exhibits the maximum and highest absorbance (absorption intensity) in the absorption spectrum of the compound obtained when the absorption spectrum of the above compound is measured.

[0028] The maximum absorption wavelength of the dye compound is located within the aforementioned wavelength range, thereby protecting the display element from ambient light and suppressing degradation, while also preventing luminescence loss from occurring in the display element's light emission. It is preferable that the dye compound, while possessing the above-mentioned absorption characteristics, does not exhibit fluorescence or phosphorescence (photoluminescence) that would impair the display performance of the organic EL element.

[0029] The dye compound is contained in a polarizing plate protective film and is useful in terms of dispersibility in resin components such as the base polymer, which are film-forming components of the polarizing plate protective film, and in maintaining transparency. Specifically, the hydrophobicity of the compound is increased by a particular substituent structure substituted on the benzotriazole skeleton, and this hydrophobicity enhances the interaction with resins and other additives, thereby suppressing the degradation of the compound by light and improving light resistance. Furthermore, it has good compatibility with the resin and the compound in terms of sp value, and even when the amount required to form the desired absorption spectrum is added, it does not cause bleed-out or whitening phenomena, thus improving durability.

[0030] <Example of synthesis> Synthesis of dye compound (compound 1)

[0031] [ka]

[0032] A 300 mL four-necked flask was fitted with a ball-type condenser, thermometer, and stirrer. 4.0 g (0.0134 mol) of (a1), 200 mL of toluene, 7.67 g (0.0532 mol) of octanoic acid, and 0.2 g (0.002 mol) of methanesulfonic acid were added, and the mixture was refluxed at 110-115 °C for 4 hours. The mixture was washed twice with 100 mL of warm water, 0.2 g of activated carbon was added, and the mixture was decolorized by refluxing and stirring. The mixture was then filtered while still hot, the filtrate was cooled to 5 °C, the precipitated crystals were filtered, washed with toluene, and dried at 60 °C to obtain 5.2 g of compound 1 (yield 91%).

[0033] The content of the dye compound according to the present invention is preferably in the range of 0.01 to 10 parts by mass, and more preferably in the range of 0.02 to 8 parts by mass, based on 100% by mass of the resin component which is a film-forming component in the polarizing plate protective film.

[0034] By setting the content of the dye compound within the above range, when a polarizing plate equipped with the polarizing plate protective film of the present invention is used in an organic EL display device, it is possible to sufficiently absorb light in a region that does not affect the light emission of the organic EL element, thereby suppressing the degradation of the organic EL element.

[0035] [3] Resin The resin used in the present invention is preferably a thermoplastic resin material, and is not limited as long as it can be handled as a film after film formation. For example, thermoplastic resins used for polarizing plate protective films include cellulose ester resins such as triacetylcellulose (TAC), cellulose acetate propionate (CAP), and diacetylcellulose (DAC), cyclic olefin resins such as cycloolefin polymers (hereinafter also called COP or cycloolefin resins), polypropylene resins such as polypropylene (PP), acrylic resins such as polymethyl methacrylate (PMMA), and polyester resins such as polyethylene terefterate (PET).

[0036] In particular, resins with high hydrophobicity have a high affinity with the dye compounds according to the present invention, allowing for control of the waveform of light absorption wavelengths, excellent UV cut properties and sharp wavelength cuts in the short-wavelength region of visible light, and enhancing the effect of reducing light emission loss in display devices. From this viewpoint, considering the polarity, hydrophilicity, and water content of the resins, cyclic olefin resins (cycloolefin resins), acrylic resins, and cellulose ester resins can be used in that order.

[0037] [3.1] Cycloolefin resins The cycloolefin resin contained in the polarizing plate protective film of the present invention is preferably a polymer of cycloolefin monomers, or a copolymer of cycloolefin monomers and other copolymerizable monomers.

[0038] The cycloolefin monomer is preferably a cycloolefin monomer having a norbornene skeleton, and more preferably a cycloolefin monomer having a structure represented by the following general formula (A-1) or (A-2).

[0039] [ka]

[0040] In general formula (A-1), R ,

[0041] , , 4 ,

[0043] , 4 , 1 ,

[0042] , , , , , 1 ~R 4 each independently represents a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms, or a polar group. p represents an integer of 0 to 2. However, it is assumed that all of R 1 ~R 4 do not simultaneously represent hydrogen atoms, and R 1 and R 2 do not simultaneously represent hydrogen atoms, and R 3 and R 4 do not simultaneously represent hydrogen atoms.

[0041] In general formula (A-1), as the hydrocarbon group having 1 to 30 carbon atoms represented by R 1 ~R 4 for example, a hydrocarbon group having 1 to 10 carbon atoms is preferable, and a hydrocarbon group having 1 to 5 carbon atoms is more preferable. The hydrocarbon group having 1 to 30 carbon atoms may further have a linking group containing, for example, a halogen atom, an oxygen atom, a nitrogen atom, a sulfur atom or a silicon atom. Examples of such a linking group include divalent polar groups such as a carbonyl group, an imino group, an ether bond, a silyl ether bond, and a thioether bond. Examples of the hydrocarbon group having 1 to 30 carbon atoms include a methyl group, an ethyl group, a propyl group, and a butyl group.

[0042] In general formula (A-1), examples of the polar group represented by R 1 ~R 4 include a carboxy group, a hydroxy group, an alkoxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an amide group, and a cyano group. Among them, a carboxy group, a hydroxy group, an alkoxycarbonyl group, and an aryloxycarbonyl group are preferable, and from the viewpoint of ensuring solubility during solution film formation, an alkoxycarbonyl group and an aryloxycarbonyl group are preferable.

[0043] In general formula (A-1), p is preferably 1 or 2 from the viewpoint of improving the heat resistance of the polarizing plate protective film. This is because when p is 1 or 2, the resulting polymer becomes bulkier, and the glass transition temperature tends to improve.

[0044] [ka]

[0045] In general formula (A-2), R 5 R represents a hydrogen atom, a hydrocarbon group having 1 to 5 carbon atoms, or an alkylsilyl group having 1 to 5 carbon atoms. 6 represents a carboxyl group, hydroxyl group, alkoxycarbonyl group, aryloxycarbonyl group, amino group, amide group, cyano group, or halogen atom (fluorine atom, chlorine atom, bromine atom, or iodine atom). p represents an integer from 0 to 2.

[0046] R in general formula (A-2) 5 It is preferable that this represents a hydrocarbon group having 1 to 5 carbon atoms, and more preferably a hydrocarbon group having 1 to 3 carbon atoms.

[0047] R in general formula (A-2) 6 Preferably, this represents a carboxyl group, a hydroxyl group, an alkoxycarbonyl group, or an aryloxycarbonyl group, and from the viewpoint of ensuring solubility during solution film formation, an alkoxycarbonyl group and an aryloxycarbonyl group are more preferred.

[0048] In general formula (A-2), p is preferably 1 or 2 from the viewpoint of improving the heat resistance of the polarizing plate protective film. This is because when p is 1 or 2, the resulting polymer becomes bulkier, and the glass transition temperature tends to improve.

[0049] Cycloolefin monomers having the structure represented by general formula (A-2) are preferred because they improve solubility in organic solvents. Generally, organic compounds lose their crystallinity by disrupting their symmetry, thus improving their solubility in organic solvents. In general formula (A-2), R 5 and R 6 Because the substitution occurs only on one side of the ring-forming carbon atoms relative to the molecular axis of symmetry, the molecular symmetry is low. In other words, cycloolefin monomers having the structure represented by general formula (A-2) have high solubility, making them suitable for the production of polarizing plate protective films by solution casting.

[0050] The content of cycloolefin monomers having the structure represented by general formula (A-2) in a polymer of cycloolefin monomers can be, for example, 70 mol% or more, preferably 80 mol% or more, and more preferably 100 mol% of the total amount of cycloolefin monomers constituting the cycloolefin resin. When a certain amount of cycloolefin monomers having the structure represented by general formula (A-2) is included, the orientation of the resin increases, and the phase difference (retardation) value tends to rise.

[0051] Specific examples of cycloolefin monomers having the structure represented by general formula (A-1) are shown in structural formulas 1 to 14, and specific examples of cycloolefin monomers having the structure represented by general formula (A-2) are shown in structural formulas 15 to 34.

[0052] [ka]

[0053] Examples of copolymerizable monomers that can copolymerize with cycloolefin monomers include copolymerizable monomers that can copolymerize with cycloolefin monomers through ring opening, and copolymerizable monomers that can copolymerize with cycloolefin monomers through addition copolymerization.

[0054] Examples of ring-opening copolymerizable monomers include cycloolefins such as cyclobutene, cyclopentene, cycloheptene, cyclooctene, and dicyclopentadiene.

[0055] Examples of copolymerizable monomers that can be added copolymerized include unsaturated double bond-containing compounds, vinyl cyclic hydrocarbon monomers, and (meth)acrylates. Examples of unsaturated double bond-containing compounds include olefin compounds having 2 to 12 (preferably 2 to 8) carbon atoms, such as ethylene, propylene, and butene. Examples of vinyl cyclic hydrocarbon monomers include vinylcyclopentene monomers such as 4-vinylcyclopentene and 2-methyl-4-isopropenylcyclopentene. Examples of (meth)acrylates include alkyl (meth)acrylates having 1 to 20 carbon atoms, such as methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and cyclohexyl (meth)acrylate.

[0056] The content of the cycloolefin monomer in a copolymer of a cycloolefin monomer and a copolymerizable monomer can be, for example, 20 to 80 mol%, preferably 30 to 70 mol%, relative to the total amount of all monomers constituting the copolymer.

[0057] As mentioned above, cycloolefin resins are polymers obtained by polymerizing or copolymerizing cycloolefin monomers having a norbornene skeleton, preferably cycloolefin monomers having a structure represented by general formula (A-1) or (A-2), and examples include the following.

[0058] (1) Cycloolefin monomer ring-opening polymer (2) A ring-opening copolymer of a cycloolefin monomer and a copolymerizable monomer that can be ring-opened therewith. (3) Hydrogenated ring-opening (co) polymers of (1) or (2) above (4) The ring-opened (co)polymer of (1) or (2) above is cyclized by a Friedel-Crafts reaction, and then the (co)polymer is hydrogenated. (5) Saturated copolymer of a cycloolefin monomer and an unsaturated double bond-containing compound (6) Addition copolymers of cycloolefin monomers with vinyl cyclic hydrocarbon monomers and hydrogenated versions thereof (7) Alternating copolymer of cycloolefin monomer and (meth)acrylate The polymers described in (1) to (7) above can all be obtained by known methods, for example, by the methods described in Japanese Patent Publication No. 2008-107534 and Japanese Patent Publication No. 2005-227606. For example, the catalyst and solvent used in the ring-opening copolymerization described in (2) above can be those described in paragraphs 0019 to 0024 of Japanese Patent Publication No. 2008-107534. The catalysts used in the hydrogenation described in (3) and (6) above can be those described in paragraphs 0025 to 0028 of Japanese Patent Publication No. 2008-107534. The acidic compound used in the Friedel-Crafts reaction described in (4) above can be those described in paragraph 0029 of Japanese Patent Publication No. 2008-107534. The catalyst used in the addition polymerization described in (5) to (7) above can be, for example, one described in paragraphs 0058 to 0063 of Japanese Patent Application Publication No. 2005-227606. The alternating copolymerization reaction described in (7) above can be carried out, for example, by the method described in paragraphs 0071 and 0072 of Japanese Patent Application Publication No. 2005-227606.

[0059] Among these, the polymers of (1) to (3) and (5) above are preferred, and the polymers of (3) and (5) above are more preferred. That is, the cycloolefin resin preferably contains at least one of the structural units represented by the following general formula (B-1) and the following general formula (B-2), and more preferably contains only the structural unit represented by general formula (B-2), or both the structural unit represented by general formula (B-1) and the structural unit represented by general formula (B-2), in order to increase the glass transition temperature and light transmittance of the resulting cycloolefin resin. The structural unit represented by general formula (B-1) is a structural unit derived from the cycloolefin monomer represented by the aforementioned general formula (A-1), and the structural unit represented by general formula (B-2) is a structural unit derived from the cycloolefin monomer represented by the aforementioned general formula (A-2).

[0060] [ka]

[0061] In general formula (B-1), X represents -CH=CH- or -CH2CH2-. 1 ~R 4 and p are R in general formula (A-1), respectively. 1 ~R 4 It is synonymous with p.

[0062] [ka]

[0063] In general formula (B-2), X represents -CH=CH- or -CH2CH2-. 5 ~R 6 and p are R in general formula (A-2), respectively. 5 ~R 6 It is synonymous with p.

[0064] The cycloolefin resin used in the present invention may be a commercially available product. Examples of commercially available cycloolefin resins include Arton G (e.g., G7810), Arton F, Arton R (e.g., R4500, R4900, and R5000), and Arton RX, all manufactured by JSR Corporation.

[0065] The intrinsic viscosity [η]inh of cycloolefin resins is 0.2 to 5 cm³ when measured at 30°C. 3 It is preferable that the range is in the range of / g, and 0.3 to 3cm 3 It is more preferable that the range is in the range of / g, and 0.4 to 1.5 cm. 3 It is even more preferable that the range is within / g.

[0066] The number-average molecular weight (Mn) of the cycloolefin resin is preferably in the range of 8,000 to 100,000, more preferably in the range of 10,000 to 80,000, and even more preferably in the range of 12,000 to 50,000. The weight-average molecular weight (Mw) of the cycloolefin resin is preferably in the range of 20,000 to 300,000, more preferably in the range of 30,000 to 250,000, and even more preferably in the range of 40,000 to 200,000. The number-average molecular weight and weight-average molecular weight of the cycloolefin resin can be measured in polystyrene equivalent by gel permeation chromatography (GPC).

[0067] <Gel Permeation Chromatography> Solvent: Methylene chloride Columns: Shodex K806, K805, K803G (three columns manufactured by Showa Denko Corporation were connected together and used) Column temperature: 25℃ Sample concentration: 0.1% by mass Detector: RI Model 504 (manufactured by GL Sciences) Pump: L6000 (manufactured by Hitachi, Ltd.) Flow rate: 1.0mL / min Calibration curve: A calibration curve was used for 13 samples of standard polystyrene (STK standard polystyrene, manufactured by Tosoh Corporation) with a Mw value in the range of 500 to 2,800,000. It is preferable to use the 13 samples at approximately equal intervals.

[0068] When the intrinsic viscosity [η]inh, number-average molecular weight, and weight-average molecular weight are within the above range, the cycloolefin resin exhibits good heat resistance, water resistance, chemical resistance, mechanical properties, and moldability as a film.

[0069] The glass transition temperature (Tg) of cycloolefin resins is typically 110°C or higher, preferably in the range of 110 to 350°C, more preferably in the range of 120 to 250°C, and even more preferably in the range of 120 to 220°C. A Tg of 110°C or higher makes it easier to suppress deformation under high-temperature conditions. On the other hand, a Tg of 350°C or lower facilitates molding and also helps to suppress resin degradation due to heat during molding.

[0070] The content of the cycloolefin resin is preferably 70% by mass or more, and more preferably 80% by mass or more, relative to the film.

[0071] [3.2] Acrylic resins The acrylic resin used in the present invention is a polymer of acrylic acid ester or methacrylic acid ester, and also includes copolymers with other monomers.

[0072] Therefore, the acrylic resin used in the present invention also includes methacrylic resin. The resin is not particularly limited, but it is preferable that it consists of methyl methacrylate units in the range of 50 to 99% by mass and other monomer units copolymerizable thereto in the range of 1 to 50% by mass.

[0073] Other units that constitute acrylic resins formed by copolymerization include alkyl methacrylates with 2 to 18 C1 of the alkyl group, alkyl acrylates with 1 to 18 C1 of the alkyl group, hydroxyalkyl acrylates such as isobornyl methacrylate and 2-hydroxyethyl acrylate, α,β-unsaturated acids such as acrylic acid and methacrylic acid, acrylamides such as acryloylmorpholine and N-hydroxyphenylmethacrylamide, divalent carboxylic acids containing unsaturated groups such as N-vinylpyrrolidone, maleic acid, fumaric acid, and itaconic acid, aromatic vinyl compounds such as styrene and α-methylstyrene, α,β-unsaturated nitriles such as acrylonitrile and methacrylonitrile, maleic anhydride, maleimide, N-substituted maleimide, glutarimide, and glutaric anhydride.

[0074] Examples of copolymerizable monomers that form units excluding glutarimide and glutaric anhydride from the above units include monomers corresponding to the above units. Specifically, examples include alkyl methacrylates with 2 to 18 C1 of the alkyl group, alkyl acrylates with 1 to 18 C1 of the alkyl group, hydroxyalkyl acrylates such as isobornyl methacrylate and 2-hydroxyethyl acrylate, α,β-unsaturated acids such as acrylic acid and methacrylic acid, acrylamides such as acryloylmorpholine and N-hydroxyphenylmethacrylamide, divalent carboxylic acids containing unsaturated groups such as N-vinylpyrrolidone, maleic acid, fumaric acid, and itaconic acid, aromatic vinyl compounds such as styrene and α-methylstyrene, α,β-unsaturated nitriles such as acrylonitrile and methacrylonitrile, maleic anhydride, maleimide, and N-substituted maleimide monomers.

[0075] Furthermore, glutarimide units can be formed, for example, by imidizing an intermediate polymer having (meth)acrylic acid ester units with a primary amine (imidizing agent) (see Japanese Patent Publication No. 2011-26563).

[0076] Glutaric anhydride units can be formed, for example, by heating an intermediate polymer having (meth)acrylic acid ester units (see Japanese Patent Publication No. 4961164).

[0077] In the present invention, the acrylic resin used is particularly preferably, from the viewpoint of mechanical strength, contains isobornyl methacrylate, acryloylmorpholine, N-hydroxyphenylmethacrylamide, N-vinylpyrrolidone, styrene, hydroxyethyl methacrylate, maleic anhydride, maleimide, N-substituted maleimide, glutaric acid anhydride, or glutarimide, among the above-mentioned constituent units.

[0078] The acrylic resin used in the present invention preferably has a weight-average molecular weight (Mw) in the range of 50,000 to 1,000,000, more preferably in the range of 100,000 to 1,000,000, and particularly preferably in the range of 200,000 to 800,000, from the viewpoint of controlling dimensional changes in response to changes in ambient temperature and humidity, and improving peelability from metal supports during film production, drying properties of organic solvents, heat resistance, and mechanical strength.

[0079] If the value is 50,000 or higher, it exhibits excellent heat resistance and mechanical strength; if it is 1,000,000 or lower, it exhibits excellent peelability from metal supports and drying properties for organic solvents.

[0080] There are no particular limitations on the method for producing the acrylic resin used in the present invention, and any known method such as suspension polymerization, emulsion polymerization, bulk polymerization, or solution polymerization may be used. Here, ordinary peroxide-based and azo-based polymer initiators can be used, and redox-based polymers can also be used. The polymerization temperature can be within the range of 30 to 100°C for suspension or emulsion polymerization, and within the range of 80 to 160°C for bulk or solution polymerization. To control the reduced viscosity of the obtained copolymer, polymerization can also be carried out using alkyl mercaptans or the like as chain transfer agents.

[0081] From the viewpoint of maintaining the mechanical strength of the film, it is preferable that the glass transition temperature (Tg) of the acrylic resin be in the range of 80 to 120°C.

[0082] Commercially available acrylic resins can also be used in this invention. Examples include Delpet 60N, 80N, 980N, SR8200 (all manufactured by Asahi Kasei Chemicals Corporation), Dianaal BR52, BR80, BR83, BR85, BR88, EMB-143, EMB-159, EMB-160, EMB-161, EMB-218, EMB-229, EMB-270, EMB-273 (all manufactured by Mitsubishi Rayon Co., Ltd.), KT75, TX400S, IPX012 (all manufactured by Denki Kagaku Kogyo Co., Ltd.), and others. Two or more types of acrylic resins can also be used in combination.

[0083] The acrylic resin used in the present invention preferably contains additives. As an example of additives, it is preferable to include acrylic particles (rubber elastic particles) described in International Publication No. 2010 / 001668 to improve the mechanical strength of the film and adjust the rate of dimensional change. Examples of commercially available multilayer acrylic granular composites include, for example, "Metablen W-341" from Mitsubishi Rayon, "Kaneace" from Kaneka Corporation, "Paraloid" from Kureha Corporation, "Acryloid" from Rohm & Haas Corporation, "Stafloid" from Aica Corporation, Chemisnow MR-2G, MS-300X (all manufactured by Soken Chemical Co., Ltd.), and "Parapet SA" from Kuraray Corporation. These can be used individually or in combination of two or more.

[0084] The volume-average particle size of the acrylic particles is 0.35 μm or less, preferably in the range of 0.01 to 0.35 μm, and more preferably in the range of 0.05 to 0.30 μm. If the particle size is above a certain level, the film can be easily stretched under heat, and if the particle size is below a certain level, the transparency of the resulting film is less likely to be impaired.

[0085] From the viewpoint of flexibility, the polarizing plate protective film of the present invention preferably has a flexural modulus (JIS K7171) of 1.5 GPa or less. More preferably, this flexural modulus is 1.3 GPa or less, and even more preferably 1.2 GPa or less. This flexural modulus varies depending on the type and amount of acrylic resin and rubber elastic particles in the film; for example, the higher the content of rubber elastic particles, the lower the flexural modulus generally becomes. Furthermore, using a copolymer of alkyl methacrylate and alkyl acrylate, etc., as the acrylic resin generally results in a lower flexural modulus than using a homopolymer of alkyl methacrylate.

[0086] [3.3] Cellulose ester resins Examples of cellulose ester resins used in the present invention include triacetylcellulose (TAC), cellulose acetate propionate, cellulose diacetate, and cellulose acetate butyrate. In addition, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polycarbonate resins, polyolefin resins such as polyethylene and polypropylene, norbornene resins, fluororesins, and cycloolefin resins may be used in combination with the cellulose ester resin.

[0087] The cellulose ester used in the polarizing plate protective film of the present invention is preferably a carboxylic acid ester having about 2 to 22 carbon atoms, and may also be an aromatic carboxylic acid ester, or preferably a lower fatty acid ester of cellulose. Here, "lower fatty acid" in "lower fatty acid ester of cellulose" means a fatty acid with 6 or fewer carbon atoms.

[0088] Furthermore, the acyl group bonded to the hydroxyl group of the glucose unit constituting the cellulose ester may be a linear hydrocarbon group, a branched hydrocarbon group, a cyclic hydrocarbon group, or the acyl group may be substituted with another substituent. When the degree of substitution of substituents bonded to the hydroxyl group of the cellulose ester is the same, if the number of carbon atoms in the lower fatty acid exceeds 7, the birefringence decreases. Therefore, the number of carbon atoms in the acyl group bonded to the hydroxyl group of the glucose unit constituting the cellulose ester is preferably 2 to 6, more preferably 2 to 4, and even more preferably 2 to 3.

[0089] In the present invention, the cellulose ester may also be an acyl group derived from a mixed acid. Preferably, an acyl group having 2 and 3 carbon atoms, or an acyl group having 2 and 4 carbon atoms, is used. Specific examples of such cellulose esters include cellulose acetate propionate, cellulose acetate butyrate, or cellulose acetate propionate butyrate, which are mixed fatty acid esters of cellulose in which propionate groups or butyrate groups are bonded in addition to acetyl groups. The butyryl groups forming the butyrate may be linear or branched. The cellulose ester is preferably cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, or cellulose acetate phthalate.

[0090] The retardation value of the protective film described above can be appropriately controlled by the type of acyl group contained in the cellulose ester and the degree of substitution of the acyl group with the pyranose ring of the cellulose resin skeleton.

[0091] The substituents bonded to the hydroxyl group of the glucose unit constituting the cellulose ester used in the protective film are preferably those that simultaneously satisfy formulas (a) and (b) below.

[0092] Formula (a): 2.0≦X+Y≦3.0 Formula (b): 0≦Y≦2.0 In formula (a) above, X is the degree of substitution of the acetyl group, and in formulas (a) and (b), Y is the degree of substitution of the propionyl group or the butyryl group. By satisfying the above two formulas, a polarizing plate protective film exhibiting excellent optical properties can be produced. Among the above cellulose esters, triacetylcellulose and cellulose acetate propionate are preferably used. For cellulose acetate propionate, it is preferable that the degree of substitution X of the acetyl group is 1.0 ≤ X ≤ 2.5, and 0.1 ≤ Y ≤ 1.5 and 2.0 ≤ X + Y ≤ 3.0.

[0093] The degree of substitution of the acyl group can be measured according to ASTM-D817-96. If the degree of substitution of the acyl group is too low, there will be many unreacted portions of the hydroxyl groups of the pyranose rings that constitute the backbone of the cellulose resin, and many of these hydroxyl groups will remain. This is undesirable because the retardation value of the polarizer protective film will change with humidity, and the ability of the polarizer protective film to protect the polarizer layer will decrease.

[0094] The number-average molecular weight of the above cellulose ester is preferably 60,000 to 300,000, and more preferably 70,000 to 200,000. By using a cellulose ester with such a number-average molecular weight, the mechanical strength of the polarizing plate protective film can be increased. The number-average molecular weight of this cellulose ester shall be the value measured by high-performance liquid chromatography under the following conditions.

[0095] Solvent: Acetone Column: MPW x 1 (manufactured by Tosoh Corporation) Sample concentration: 0.2 (mass / volume)% Flow rate: 1.0mL / min Sample injection volume: 300 μL Standard sample: Standard polystyrene Temperature: 23℃

[0096] The above-mentioned cellulose esters can be prepared by conventional methods. For example, the cellulose used as a raw material for cellulose esters is not particularly limited, but examples include cotton linters, wood pulp, and kenaf. Furthermore, the cellulose esters obtained from these materials may be mixed and used in any proportion.

[0097] When acid anhydrides such as acetic anhydride, propionic anhydride, or butyric anhydride are used as acylating agents for the above-mentioned cellulose raw materials, the reaction is carried out by an organic acid such as acetic acid or an organic solvent such as dichloromethane and a protic catalyst such as sulfuric acid. When acid chlorides (CH3COCl, C2H5COCl, C3H7COCl) are used as acylating agents, basic compounds such as amines are used as catalysts. The acylation of cellulose raw materials can be synthesized by the method described in Japanese Patent Publication No. 10-45804.

[0098] [4] Other additives The polarizing plate protective film of the present invention may further contain other additives such as antioxidants, plasticizers, fine particles, antistatic agents, release agents, and thickeners. In particular, from the viewpoint of further enhancing the effects of the present invention, it is preferable to use antioxidants and fine particles.

[0099] <Antioxidant> The polarizing plate protective film of the present invention preferably contains an antioxidant. Antioxidants, also known as degradation inhibitors, play a role in delaying or preventing the decomposition of the film by, for example, halogens in the residual solvent amount in the film or phosphoric acid from phosphoric acid-based plasticizers.

[0100] In the present invention, by using the dye compound according to the present invention in combination with an antioxidant, the effect of sharpening the light absorption waveform of the dye compound can be obtained. As the antioxidant, a hindered phenol compound is particularly preferred, and the hindered phenol compound and the dye compound according to the present invention have a high affinity for each other. Due to their interaction, the light absorption waveform tends to become sharper, light absorption on the long wavelength side is suppressed, and the effect of suppressing luminescence loss can be obtained.

[0101] Examples of such hindered phenol-based antioxidants include 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], and 2,4-bis-(n-octylthio)-6-(4-hydroxy-3,5-di-t-butylanilino). Examples include -1,3,5-triazine, 2,2-thio-diethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, N,N′-hexamethylenebis(3,5-di-t-butyl-4-hydroxyhydrocinnamamide), 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, and tris-(3,5-di-t-butyl-4-hydroxybenzyl)-isocyanurate.

[0102] In particular, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], and triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate] are preferred. In addition, hydrazine-based metal deactivators such as N,N'-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl]hydrazine or phosphorus-based processing stabilizers such as tris(2,4-di-t-butylphenyl)phosphite may be used in combination.

[0103] As preferred hindered phenol antioxidants, commercially available products can be used, and examples include Irganox 1076 and Irganox 1010 from BASF Japan Ltd.

[0104] [ka]

[0105] The amount of these compounds added is 5% by mass or less, preferably 2% by mass or less, and more preferably 0.5 to 1% by mass, based on 100% by mass of the resin.

[0106] <Fine particles> The polarizing plate protective film of the present invention preferably contains fine particles.

[0107] Examples of inorganic compounds used in the present invention include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate. Fine particles of organic compounds can also be preferably used. Examples of organic compounds include polytetrafluoroethylene, cellulose acetate, polystyrene, polymethyl methacrylate, polypropyl methacrylate, polymethyl acrylate, polyethylene carbonate, acrylic styrene resin, silicone resin, polycarbonate resin, benzoguanamine resin, melamine resin, polyolefin powder, polyester resin, polyamide resin, polyimide resin, or polyfluoroethylene resin, starch, and pulverized and classified organic polymer compounds. Alternatively, polymer compounds synthesized by suspension polymerization, polymer compounds formed into spheres by spray drying or dispersion methods, or inorganic compounds can be used.

[0108] The average particle size of the primary particles of the fine particles is preferably in the range of 5 to 400 nm, and more preferably in the range of 10 to 300 nm.

[0109] These may be contained mainly as secondary aggregates with a particle size in the range of 0.05 to 0.3 μm, but it is also preferable that particles with an average particle size in the range of 100 to 400 nm be contained as primary particles without aggregation.

[0110] Fine particles containing silicon are preferred in that they reduce the turbidity of the film, and silicon dioxide is particularly preferred. Fine silicon dioxide particles are commercially available and can be used, for example, under the trade names Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, and TT600 (all manufactured by Nippon Aerosil Co., Ltd.).

[0111] In particular, silicon-containing fine particles have a high affinity for the dye compound according to the present invention, and when used in combination, the light absorption waveform becomes sharper, light absorption on the longer wavelength side is suppressed, and the light emission loss of the display device can be reduced. Among the silicon-containing particles, R812 or R972 are preferred, and silicon-containing particles with higher hydrophobicity have a high affinity for the dye compound according to the present invention, and the effect of reducing the light emission loss is obtained through their interaction.

[0112] These fine particles may be used individually or in combination of two or more types. The content of the fine particles should be 10% by mass or less, preferably 5% by mass or less, and more preferably 0.5 to 2% by mass or less, based on 100% by mass of the resin.

[0113] In the present invention, when adding fine particles during the manufacturing process, it is preferable to mix them by in-line addition. For example, in-line mixers such as a static mixer (manufactured by Toray Engineering) or SWJ (Toray Hi-Mixer static in-tube mixer) are preferably used.

[0114] <UV absorbers> The polarizing plate protective film of the present invention may also contain an ultraviolet absorber as another dye compound, if necessary.

[0115] The aforementioned "ultraviolet absorber" is preferably a compound whose maximum absorption wavelength is within the range of 300 to 359 nm in the absorption spectrum of the 300 to 460 nm wavelength range, but is not particularly limited as long as its maximum absorption wavelength is in the wavelength range of 300 to 359 nm.

[0116] Examples of UV absorbers that can be used include triazine-based UV absorbers, benzotriazole-based UV absorbers, benzophenone-based UV absorbers, oxybenzophenone-based UV absorbers, salicylate-based UV absorbers, and cyanoacrylate-based UV absorbers. These can be used individually or in combination of two or more.

[0117] Among these, triazine-based UV absorbers and benzotriazole-based UV absorbers are preferred, and it is preferable that the UV absorber be at least one selected from the group consisting of triazine-based UV absorbers having two or fewer hydroxyl groups per molecule and benzotriazole-based UV absorbers having one benzotriazole skeleton per molecule. These UV absorbers are preferred because they have good solubility in resin components such as base polymers, which are film-forming components of optical films containing the UV absorber. Furthermore, these UV absorbers are preferred because they have high UV absorption capacity around a wavelength of 380 nm.

[0118] Triazine-based UV absorbers having two or fewer hydroxyl groups in one molecule include, specifically, 2,4-bis-[{4-(4-ethylhexyloxy)-4-hydroxy}-phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine (Tinosorb S, manufactured by BASF), 2,4-bis[2-hydroxy-4-butoxyphenyl]-6-(2,4-dibutoxyphenyl)-1,3,5-triazine (TINUVIN 460, manufactured by BASF), and the reaction product of 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl)-5-hydroxyphenyl and [(C10-C16 (mainly C12-C13) alkyloxy)methyl]oxirane (TINUVIN TINUVIN 405 (BASF), 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-[3-(dodecyloxy)-2-hydroxypropoxy]phenol), reaction product of 2-(2,4-dihydroxyphenyl)-4,6-bis-(2,4-dimethylphenyl)-1,3,5-triazine and (2-ethylhexyl)-glycidic acid ester (TINUVIN 405, BASF), 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]-phenol (TINUVIN 1577, BASF), 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]-phenol (ADK STAB Examples include LA46 (manufactured by ADEKA Corporation), 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine (TINUVIN 479, manufactured by BASF), and 6,6′,6′′-(1,3,5-triazine-2,4,6-triyl)tris(3-hexyloxy-2-methylphenol) (LA-F70, manufactured by ADEKA Corporation).

[0119] Furthermore, examples of benzotriazole-based UV absorbers having one benzotriazole skeleton in one molecule include 2-(2H-benzotriazole-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (TINUVIN 928, manufactured by BASF), 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole (TINUVIN PS, manufactured by BASF), benzenepropanoic acid and 3-(2H-benzotriazole-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy(C7-9 side chain and linear alkyl) ester compounds (TINUVIN 384-2, manufactured by BASF), and 2-(2H-benzotriazole-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (TINUVIN Reaction product of methyl-3-(3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl)propionate / polyethylene glycol 300 (TINUVIN 1130, BASF), 2-(2H-benzotriazol-2-yl)-p-cresol (TINUVIN P, BASF), 2(2H-benzotriazol-2-yl)-4-6-bis(1-methyl-1-phenylethyl)phenol (TINUVIN 234, BASF), 2-[5-chloro(2H)-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol (TINUVIN 326, BASF), 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (TINUVIN 328 (manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (TINUVIN 329, manufactured by BASF), reaction product of methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate and polyethylene glycol 300 (TINUVIN 213, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol (TINUVIN 571, manufactured by BASF), 2-[2-hydroxy-3-(3,4,5,Examples include 6-tetrahydrophthalimidomethyl)-5-methylphenyl]benzotriazole (Sumisorb 250, manufactured by Sumitomo Chemical Co., Ltd.), 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole (SeeSorb 703, manufactured by Cipro Chemical Co., Ltd., or KEMISORB 73, manufactured by Cipro Chemical Co., Ltd.).

[0120] Furthermore, examples of the above-mentioned benzophenone-based ultraviolet absorbers (benzophenone compounds) and oxybenzophenone-based ultraviolet absorbers (oxybenzophenone compounds) include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (anhydrous and trihydrate), 2-hydroxy-4-octyloxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 4-benzyloxy-2-hydroxybenzophenone, 2,2′,4,4′-tetrahydroxybenzophenone, 2,2′-dihydroxy-4,4-dimethoxybenzophenone, 2,2′,4,4′-tetrahydroxybenzophenone (SeeSorb 106, manufactured by Cipro Chemical Co., Ltd.), and 2,2′-dihydroxy-4-methoxybenzophenone (KEMISORB 111, manufactured by Chemipro Chemical Co., Ltd.).

[0121] Furthermore, examples of the above-mentioned salicylic acid ester-based ultraviolet absorbers (salicylic acid ester compounds) include phenyl-2-acryloyloxybenzoate, phenyl-2-acryloyloxy-3-methylbenzoate, phenyl-2-acryloyloxy-4-methylbenzoate, phenyl-2-acryloyloxy-5-methylbenzoate, phenyl-2-acryloyloxy-3-methoxybenzoate, phenyl-2-hydroxybenzoate, phenyl-2-hydroxy-3-methylbenzoate, phenyl-2-hydroxy-4-methylbenzoate, phenyl-2-hydroxy-5-methylbenzoate, phenyl-2-hydroxy-3-methoxybenzoate, and 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate (TINUVIN120, manufactured by BASF).

[0122] Examples of the above-mentioned cyanoacrylate-based ultraviolet absorbers (cyanoacrylate compounds) include alkyl-2-cyanoacrylate, cycloalkyl-2-cyanoacrylate, alkoxyalkyl-2-cyanoacrylate, alkenyl-2-cyanoacrylate, and alkynyl-2-cyanoacrylate.

[0123] UV absorbers may be used alone or in mixtures of two or more types. The UV absorber content is expressed as parts by mass of UV absorber per 100 parts by mass of resin components, which are film-forming components of the optical film.

[0124] For example, when an ultraviolet absorber is contained in an optical film, the amount of ultraviolet absorber per 100 parts by mass of the constituent resin of the optical film is preferably in the range of 0.1 to 8 parts by mass, and more preferably in the range of 0.5 to 5 parts by mass.

[0125] By setting the content of the ultraviolet absorber within the above range, the ultraviolet absorber-containing layer can fully exhibit its ultraviolet absorption function, which is preferable. Furthermore, when the polarizing plate used in the present invention is used in an organic EL display device, the inclusion of the above compound (D) and the ultraviolet absorber provides a function to protect the organic EL display element from ambient light, thereby maintaining the quality of the organic EL display device over a long period of time.

[0126] [5] Manufacturing of polarizing plate protective film As a method for manufacturing the polarizing plate protective film of the present invention, conventional methods such as the inflation method, T-die method, calendering method, cutting method, casting method, emulsion method, and hot pressing method can be used. However, from the viewpoint of suppressing discoloration, suppressing foreign matter defects, and suppressing optical defects such as die lines, solution casting and molten casting are preferred as film formation methods. Solution casting is particularly preferred because the temperature during the processing step is low, and therefore it is more preferable from the viewpoint of imparting high functionality by using various additives. The "solution casting method" preferred for the present invention will be described below.

[0127] Specifically, to manufacture a polarizing plate protective film by solution casting, a manufacturing method including the following steps (1) to (3) is used. Furthermore, the manufacturing method preferably includes step (4). (1) A step to obtain a dope comprising a film-forming component containing a thermoplastic resin, the compound to be added (D), and an optional additive and solvent. (2) A process in which the obtained dope is cast onto a support, dried, and peeled off to obtain a film-like material. (3) A process of drying the obtained film-like material while stretching it as needed. (4) A process of winding up the obtained polarizing plate protective film to obtain a roll body.

[0128] Regarding step (1) A dope is prepared by dissolving or dispersing a film-forming component containing a thermoplastic resin, the compound (D) to be added, and additives such as antioxidants and fine particles in a solvent.

[0129] The solvent used for doping includes at least an organic solvent (good solvent) capable of dissolving the thermoplastic resin. If compound (D) is included, it is preferable that the organic solvent also has high solubility for these additives. Examples of good solvents include chlorinated organic solvents such as dichloromethane and non-chlorinated organic solvents such as methyl acetate, ethyl acetate, acetone, and tetrahydrofuran. Among these, dichloromethane is preferred.

[0130] The solvent used for doping may further contain a poor solvent. Examples of poor solvents include linear or branched aliphatic alcohols having 1 to 4 carbon atoms. When the proportion of alcohol in the dope increases, the film-like material is more likely to gel, and peeling from the metal support is easier. Examples of linear or branched aliphatic alcohols having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Of these, ethanol is preferred due to its dope stability, relatively low boiling point, and good drying properties.

[0131] Regarding step (2) The resulting dope is cast onto a support. Doping can be performed by extruding it from a casting die.

[0132] Next, the solvent in the dope cast onto the support is evaporated and dried. The dried dope is peeled off the support to obtain a film-like material.

[0133] The amount of residual solvent in the dope when peeling it from the support (the amount of residual solvent in the film-like material at the time of peeling) is preferably 20% by mass or more, and more preferably 20 to 30% by mass. If the amount of residual solvent at the time of peeling is 30% by mass or less, it is easier to suppress excessive stretching of the film-like material due to peeling.

[0134] The amount of residual solvent in the dope after stripping is defined by the following formula. The same applies below.

[0135] Residual solvent content of dope (mass %) = (mass of dope before heat treatment - mass of dope after heat treatment) / mass of dope after heat treatment × 100 Note that the heat treatment used to measure the amount of residual solvent refers to a heat treatment at 140°C for 30 minutes.

[0136] The amount of residual solvent during peeling can be adjusted by the drying temperature and time of the dope on the support, the temperature of the support, and other factors.

[0137] Regarding step (3) The resulting film-like material is dried. Drying may be carried out in one step or in multiple steps. Furthermore, drying may be performed while stretching the material as needed.

[0138] For example, the drying process for a film-like material may include a step of pre-drying the film-like material (pre-drying step), a step of stretching the film-like material (stretching step), and a step of drying the stretched film-like material (main drying step).

[0139] (Pre-drying process) The pre-drying temperature (drying temperature before stretching) can be higher than the stretching temperature. Specifically, when the glass transition temperature of the thermoplastic resin is Tg, it is preferably (Tg-50) to (Tg+50)°C. If the pre-drying temperature is (Tg-50)°C or higher, the solvent is easily evaporated to an appropriate degree, making it easier to transport (handling), and if it is (Tg+50)°C or lower, the solvent does not evaporate too much, so the stretchability in the subsequent stretching process is less likely to be impaired. The initial drying temperature can be measured as the ambient temperature, such as the temperature inside the stretcher or the hot air temperature, when drying is performed by a non-contact heating type while transporting with a tenter stretcher or rollers.

[0140] (Stretching process) The stretching may be performed according to the required optical properties, such as the retardation value, and it is preferable to stretch in at least one direction, but it may also be stretched in two mutually orthogonal directions (for example, biaxial stretching in the width direction of the film (TD direction) and the transport direction (MD direction) perpendicular to it).

[0141] The stretching ratio when manufacturing polarizing plate protective films is preferably 5 to 100%, and more preferably 20 to 100%. In the case of biaxial stretching, it is preferable that the stretching ratio in each direction is within the above range.

[0142] The stretching ratio (%) is defined as (stretched size of the film after stretching - stretched size of the film before stretching) / (stretched size of the film before stretching) × 100. When biaxial stretching is performed, it is preferable to use the above stretching ratio for both the TD direction and the MD direction.

[0143] The stretching temperature (drying temperature during stretching) is preferably above Tg(°C), and more preferably between (Tg+10) and (Tg+50)°C, where Tg is the glass transition temperature of the thermoplastic resin, as described above. When the stretching temperature is above Tg(°C), preferably above (Tg+10)°C, the solvent is easily evaporated to an appropriate degree, making it easier to adjust the stretching tension to an appropriate range. When the stretching temperature is below (Tg+50)°C, the solvent does not evaporate excessively, so the stretchability is not easily impaired. The stretching temperature during the manufacture of polarizing plate protective film can be, for example, 115°C or higher. As described above, it is preferable to measure the ambient temperature, such as the temperature inside the stretching machine, to determine the stretching temperature.

[0144] The amount of residual solvent in the film at the start of stretching is preferably about the same as the amount of residual solvent in the film at the time of peeling, for example, preferably 20 to 30% by mass, and more preferably 25 to 30% by mass.

[0145] Stretching of a film-like material in the TD direction (width direction) can be done, for example, by fixing both ends of the film-like material with clips or pins and widening the distance between the clips or pins in the direction of travel (tenter method). Stretching of a film-like material in the MD direction can be done, for example, by creating a difference in peripheral speed between multiple rolls and utilizing the difference in peripheral speed between them (roll method).

[0146] (Main drying process) From the viewpoint of further reducing the amount of residual solvent, it is preferable to further dry the film-like material obtained after stretching. For example, it is preferable to further dry the film-like material obtained after stretching while conveying it with rolls or the like.

[0147] The drying temperature (or drying temperature in the case of unstretched material) is preferably (Tg-50) to (Tg-30)°C, and more preferably (Tg-40) to (Tg-30)°C, where Tg is the glass transition temperature of the thermoplastic resin. If the post-drying temperature is (Tg-50)°C or higher, the solvent can be sufficiently volatilized and removed from the film-like material after stretching, and if it is (Tg-30)°C or lower, deformation of the film-like material can be highly suppressed. As described above, it is preferable to measure the ambient temperature, such as the temperature of hot air, to determine the drying temperature.

[0148] Regarding step (4) The resulting polarizing plate protective film is preferably in a long, rectangular shape. The long, rectangular polarizing plate protective film is wound into a roll to form a roll body.

[0149] The length of the elongated polarizing plate protective film is not particularly limited, but it can be, for example, around 100 to 10,000 meters. The width of the polarizing plate protective film is preferably 1 meter or more, and more preferably 1.3 to 4 meters.

[0150] The thickness of the polarizing plate protective film can be determined as appropriate, but generally it is preferable to be in the range of 1 to 500 μm from the standpoint of strength, workability such as handling, and thinness. The thickness of the polarizing plate protective film is more preferably in the range of 5 to 50 μm, and even more preferably in the range of 10 to 45 μm.

[0151] Furthermore, the dye compound according to the present invention has improved compatibility with resins, does not cause bleed-out or whitening phenomena, and has improved durability, so it can be preferably applied to thin polarizing plate protective films with a thickness of 1 μm or more and less than 10 μm. It is possible to manufacture thin polarizing plates using thin polarizing plate protective films (hereinafter also referred to as "thin polarizing plate protective films").

[0152] <Manufacturing of thin-film polarizing plate protective films> Another embodiment of the present invention is a method for manufacturing a thin film polarizing plate protective film, comprising the steps of: 1) obtaining a solution for a thin film polarizing plate protective film; 2) applying the obtained solution for a thin film polarizing plate protective film to the surface of a support; and 3) removing the solvent from the applied solution for a thin film polarizing plate protective film to form a thin film polarizing plate protective film.

[0153] 1) Steps to obtain a solution for a protective film for thin-film polarizing plates. The process for obtaining the solution for the thin-film polarizing plate protective film is the same as the process for preparing the "dope" described above, and can be referred to.

[0154] 2) Step of applying a solution for the protective film of the thin film polarizing plate. Next, the obtained thin-film polarizing protective film solution is applied to the surface of the support. Specifically, the obtained thin-film polarizing protective film solution is coated onto the surface of the support. The laminate of the support and the thin-film polarizing protective film is also called a "laminated film."

[0155] <Support> The support is used to support the thin-film polarizing plate protective film and usually includes a resin film. The thickness of the support is preferably 50 μm or less. Although the support is thin, it needs to have a certain degree of strength (stiffness and rigidity) as a support, so the thickness is preferably in the range of 15 to 45 μm, and more preferably in the range of 20 to 40 μm.

[0156] Examples of resins that can be used include cellulose ester resins, cyclic olefin resins, polypropylene resins, acrylic resins, polyester resins, polyarylate resins, and styrene resins or composite resins thereof. Among these, polyester resins are preferred because they offer excellent storage properties in high-humidity environments.

[0157] Examples of resin films include polyester resins (e.g., polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), etc.). Among these, polyester resin films containing polyethylene terephthalate (PET) or polyethylene naphthalate (PEN) are preferred from the viewpoint of ease of handling.

[0158] The resin film may be heat-treated (thermally relaxed) or stretched.

[0159] The heat treatment is performed to reduce residual stress in the resin film (for example, residual stress due to stretching), and is not particularly limited, but can be carried out in the range of (Tg+60) to (Tg+180)°C, where Tg is the glass transition temperature of the resin constituting the resin film.

[0160] The stretching process is performed to increase the residual stress of the resin film, and it is preferable to perform the stretching process in two axial directions of the resin film, for example. The stretching process can be performed under any conditions, for example, at a stretching ratio of approximately 120 to 900%. Whether the resin film is stretched can be confirmed, for example, by checking whether there is an in-plane slow layer axis (an axis extending in the direction in which the refractive index is maximum). The stretching process may be performed before or after lamination of the thin-film polarizing plate protective film, but it is preferable to stretch it before lamination.

[0161] Polyester resin films (also simply called polyester films) can be commercially available products, and for example, polyethylene terephthalate film TN100 (manufactured by Toyobo Co., Ltd.) and MELINEX ST504 (manufactured by Teijin DuPont Films Ltd.) can be suitably used.

[0162] The support may further have a release layer provided on the surface of the resin film. The release layer can facilitate the separation of the support from the thin-film polarizing plate protective film when manufacturing the polarizing plate.

[0163] The release layer may contain known release agents and is not particularly limited. Examples of release agents included in the release layer include silicone-based release agents and non-silicone-based release agents.

[0164] Examples of silicone-based release agents include known silicone resins. Examples of non-silicone-based release agents include long-chain alkyl pendant polymers obtained by reacting long-chain alkyl isocyanates with polyvinyl alcohol or ethylene-vinyl alcohol copolymers, olefin resins (e.g., copolymer polyethylene, cyclic polyolefins, polymethylpentene), polyarylate resins (e.g., polycondensates of aromatic dicarboxylic acid components and divalent phenol components), and fluororesins (e.g., polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), PFA (polymer of tetrafluoroethylene and perfluoroalkoxyethylene), FEP (polymer of tetrafluoroethylene and hexafluoropropylene), ETFE (polymer of tetrafluoroethylene and ethylene)).

[0165] The thickness of the release layer is not particularly limited, as long as it is sufficient to achieve the desired release properties, but it is preferably in the range of 0.1 to 1.0 μm.

[0166] The support may contain a plasticizer as an additive. The plasticizer is not particularly limited, but it is preferably selected from polyhydric alcohol ester plasticizers, phthalate ester plasticizers, citric acid plasticizers, fatty acid ester plasticizers, phosphate ester plasticizers, polyhydric carboxylic acid ester plasticizers, and polyester plasticizers.

[0167] Furthermore, the support can also contain the aforementioned ultraviolet absorbers and fine particles.

[0168] The support used in this invention can be manufactured using conventional methods such as inflation, T-die, calendering, cutting, casting, emulsion, and hot pressing. However, from the viewpoint of suppressing discoloration, foreign matter defects, and optical defects such as die lines, solution casting and molten casting are preferred as film formation methods. Furthermore, with solution casting, the temperature during the processing step is low, which allows for the use of various additives to enhance functionality.

[0169] It is preferable to form the thin-film polarizing plate protective film of the present invention using the support manufactured as described above by the following method.

[0170] The method for applying the solution for the thin-film polarizing plate protective film is not particularly limited and may be any known method such as the back roll coating method, gravure coating method, spin coating method, wire bar coating method, or roll coating method. Among these, the back coating method is preferred from the viewpoint of forming a coating film with a thin and uniform thickness.

[0171] 3) Process of forming a thin film polarizing plate protective film Next, the solvent is removed from the thin-film polarizing plate protective film solution applied to the support to form the thin-film polarizing plate protective film.

[0172] Specifically, the solution for the thin-film polarizing plate protective film applied to the support is dried. Drying can be done, for example, by blowing air or heating. Among these methods, drying by blowing air is preferable from the viewpoint of suppressing curling of the thin-film polarizing plate protective film.

[0173] 4) A process of winding up a thin film polarizing plate protective film to obtain a roll. The obtained strip-shaped thin film polarizing plate protective film is wound into a roll in a direction perpendicular to its width direction to form a roll body.

[0174] The length of the strip-shaped thin-film polarizing plate protective film is not particularly limited, but can be, for example, about 100 to 10,000 m. The width of the strip-shaped laminated film is preferably 1 m or more, and more preferably 1.1 to 4 m. From the viewpoint of improving the uniformity of the film, it is more preferably 1.3 to 2.5 m.

[0175] [Manufacturing equipment] The thin-film polarizing plate protective film used in the present invention can be manufactured, for example, by the manufacturing apparatus shown in Figure 4.

[0176] Figure 4 is a schematic diagram of a manufacturing apparatus B200 for carrying out the manufacturing method of a thin-film polarizing plate protective film according to this embodiment. The manufacturing apparatus B200 has a supply unit B210, a coating unit B220, a drying unit B230, a cooling unit B240, and a winding unit B250. Ba to Bd indicate conveying rolls for conveying the support B110.

[0177] The supply unit B210 has a feeding device (not shown) that feeds out a roll body B201 of a strip-shaped support B110 wound on a core.

[0178] The coating section B220 is a coating apparatus comprising a backup roll B221 that holds the support B110, a coating head B222 that applies a thin film polarizing plate protective film solution to the support B110 held by the backup roll B221, and a reduced pressure chamber B223 provided upstream of the coating head B222.

[0179] The flow rate of the thin-film polarizing plate protective film solution discharged from the coating head B222 can be adjusted by a pump (not shown). The flow rate of the thin-film polarizing plate protective film solution discharged from the coating head B222 is set to an amount that allows for the stable formation of a coating layer of a predetermined thickness when continuously coated under pre-adjusted conditions for the coating head B222.

[0180] The vacuum chamber B223 is a mechanism for stabilizing the bead (accumulation of coating liquid) formed between the thin film polarizing plate protective film solution from the coating head B222 and the support B110 during coating, and the degree of vacuum is adjustable. The vacuum chamber B223 is connected to a vacuum blower (not shown) and the inside is depressurized. The vacuum chamber B223 is kept free of air leaks, and the gap with the backup roll is also adjusted to be narrow, enabling the formation of a stable coating liquid bead.

[0181] The drying unit B230 is a drying apparatus for drying a coating applied to the surface of the support B110, and includes a drying chamber B231, a drying gas inlet B232, and an outlet B233. The temperature and airflow of the drying air are appropriately determined depending on the type of coating and the type of support B110. By setting conditions such as the temperature and airflow of the drying air and the drying time in the drying unit B230, the amount of residual solvent in the coating after drying can be adjusted. The amount of residual solvent in the coating after drying can be measured by comparing the unit mass of the coating after drying with the mass of the coating after it has been thoroughly dried.

[0182] (Amount of residual solvent) Since thin-film polarizing plate protective films are obtained by applying a solution for thin-film polarizing plate protective films, residual solvents originating from the solution may remain. The amount of residual solvent can be controlled by factors such as the concentration of the solvent and coating solution used, the air velocity applied to the drying of the thin-film polarizing plate protective film, the drying temperature and time, the conditions of the drying chamber (outside air or internal air circulation), and the heating temperature of the back roll during coating.

[0183] As mentioned earlier, high-speed drying creates a sparser film, allowing for control over the surface condition.

[0184] From the viewpoint of the curl balance of the thin film polarizing plate protective film, it is preferable that the amount of residual solvent in the thin film polarizing plate protective film satisfies the following inequality 1, where S1 is the amount of residual solvent in the thin film polarizing plate protective film.

[0185] formula 1 10 <S1<1000(ppm) Specifically, the residual solvent content of the thin-film polarizing protective film is more preferably less than 800 ppm, and more preferably between 500 and 700 ppm, considering the curl balance of the thin-film polarizing protective film. Furthermore, by selecting a solvent and coating process that leaves some solvent residue on the support, the adhesion between the support and the thin-film polarizing protective film is improved. The residual solvent content on the support is preferably in the range of 10 to 100 ppm.

[0186] The amount of residual solvent in the support and thin-film polarizing plate protective film can be measured by headspace gas chromatography. In headspace gas chromatography, the sample is sealed in a container, heated, and the container is filled with volatile components. The gas from the container is then quickly injected into a gas chromatograph, and the volatile components are quantified while identifying the compounds by mass spectrometry. The headspace method allows for the observation of all peaks of volatile components using a gas chromatograph, and by using an analytical method that utilizes electromagnetic interactions, it is possible to quantify volatile substances and monomers with high accuracy.

[0187] The cooling unit B240 cools the temperature of the support B110, which has a coating (thin-film polarizing protective film) obtained by drying in the drying unit B230, and adjusts it to an appropriate temperature. The cooling unit B240 has a cooling chamber B241, a cooling air inlet B242, and a cooling air outlet B243. The temperature and airflow of the cooling air can be appropriately determined depending on the type of coating and the type of support B110. Furthermore, if an appropriate cooling temperature can be achieved without the cooling unit B240, the cooling unit B240 may be omitted.

[0188] The winding section B250 is a winding device (not shown) for winding the support B110, on which a thin film polarizing plate protective film is formed, to obtain a roll body B251.

[0189] [6] Polarizer layer The polarizer layer is an element layer that allows only light with a specific polarization plane to pass through. Examples of polarizer layers include hydrophilic polymer films such as polyvinyl alcohol-based films, partially formalized polyvinyl alcohol-based films, and partially saponified ethylene-vinyl acetate copolymer films, which are uniaxially stretched after adsorbing dichroic substances such as iodine or dichroic dyes, as well as polyene-based oriented films such as dehydrated polyvinyl alcohol or dehydrochlorinated polyvinyl chloride. Among these, a polarizer layer consisting of a polyvinyl alcohol-based film and a dichroic substance such as iodine is preferred. The thickness of these polarizer layers is not particularly limited, but is generally around 5 to 80 μm.

[0190] A polarizer layer obtained by dyeing a polyvinyl alcohol-based film with iodine and uniaxially stretching it can be produced, for example, by dyeing the polyvinyl alcohol by immersing it in an aqueous solution of iodine and stretching it to 3 to 7 times its original length. If necessary, it can also be immersed in an aqueous solution of potassium iodide, which may contain boric acid, zinc sulfate, zinc chloride, etc. Furthermore, if necessary, the polyvinyl alcohol-based film may be immersed in water and washed before dyeing. Washing the polyvinyl alcohol-based film with water not only cleans away dirt and anti-blocking agents from the surface of the polyvinyl alcohol-based film, but also has the effect of preventing unevenness such as uneven dyeing by swelling the polyvinyl alcohol-based film. Stretching may be performed after dyeing with iodine, stretching while dyeing, or dyeing with iodine after stretching. Stretching can also be performed in aqueous solutions of boric acid or potassium iodide, or even in a water bath.

[0191] Furthermore, in the present invention, a thin polarizer layer with a thickness of 10 μm or less can also be used. From the viewpoint of thinning, a thickness of 1 to 7 μm is preferable. Such a thin polarizer layer is preferable because it has little thickness variation, excellent visibility, excellent durability due to little dimensional change, and furthermore, the thickness of the polarizing film can be reduced.

[0192] Examples of thin polarizer layers include the thin polarizing films described in Japanese Patent Publication No. 51-069644, Japanese Patent Publication No. 2000-338329, International Publication No. 2010 / 100917, Japanese Patent Publication No. 4751481, and Japanese Patent Publication No. 2012-073563. These thin polarizing films can be obtained by a manufacturing method that includes a step of stretching a polyvinyl alcohol-based resin (hereinafter also referred to as PVA-based resin) layer and a stretching resin substrate in a laminated state, and a step of dyeing. With this manufacturing method, even if the PVA-based resin layer is thin, it can be stretched without problems such as breakage due to stretching because it is supported by the stretching resin substrate.

[0193] As for the thin polarizing film, among manufacturing methods that include a step of stretching in a laminated state and a step of dyeing, it is preferable to obtain one that includes a step of stretching in an aqueous boric acid solution, as described in International Publication No. 2010 / 100917, International Publication No. 2010 / 100917, or Japanese Patent Publication No. 4751481 or Japanese Patent Publication No. 2012-073563, in that it can be stretched to a high magnification and its polarization performance can be improved. In particular, it is preferable to obtain one that includes a step of auxiliary air stretching before stretching in an aqueous boric acid solution, as described in Japanese Patent Publication No. 4751481 or Japanese Patent Publication No. 2012-073563.

[0194] [7] Phase difference film Any phase difference film that has a phase difference and can function as an optical compensation layer can be used. When using a transparent film with a phase difference, its phase difference characteristics can be appropriately adjusted to the value required for optical compensation.

[0195] As a phase difference film, for example, if the refractive index in the slow phase axis direction within the plane is nx, the refractive index in the fast phase axis direction within the plane is ny, and the refractive index in the thickness direction is nz, then a film that satisfies the following relationships is selected and used according to various applications: nx=ny>nz, nx>ny>nz, nx>ny=nz, nx>nz>ny, nz=nx>ny, nz>nx>ny, and nz>nx=ny. Note that nx=ny includes not only the case where nx and ny are completely identical, but also the case where nx and ny are substantially the same. Similarly, ny=nz includes not only the case where ny and nz are completely identical, but also the case where ny and nz are substantially the same.

[0196] When polarizers are used in organic EL display devices, the phase difference film is preferably a quarter-wave plate with an in-plane retardation of 1 / 4 wavelength (approximately 100-170 nm). This is preferable because laminating the polarizer layer and the quarter-wave plate (phase difference film) allows it to function as an anti-reflective circular polarizer for organic EL display devices.

[0197] In other words, when external light incident on this organic EL display device, only the linearly polarized component is transmitted by the polarizer layer. This linearly polarized light is generally converted to elliptically polarized light by the phase difference film, but in particular, when the phase difference film is a quarter-wave plate and the angle between the phase difference film and the polarization direction is π / 4, it becomes circularly polarized light.

[0198] This circularly polarized light passes through the transparent substrate, transparent electrodes, and organic thin film in the organic EL panel, is reflected by the metal electrodes, and then passes through the organic thin film, transparent electrodes, and transparent substrate again, becoming linearly polarized again by the phase difference film. Since this linearly polarized light is perpendicular to the polarization direction of the polarizer layer, it cannot pass through the polarizer layer. As a result, the mirror surface of the metal electrodes can be completely shielded.

[0199] As the phase difference film, a stretched film obtained by stretching a film in which a thermoplastic resin is used as the film-forming component can be suitably used. As the thermoplastic resin, the same thermoplastic resin as described for the constituent material of the polarizing plate protective film can be used.

[0200] The phase difference film may also contain other additives such as fine particles, phase difference adjusters, antioxidants, plasticizers, antistatic agents, release agents, and thickeners, to the extent that they do not impair the effects of this embodiment.

[0201] The phase difference film may be a single-layer or a laminated film of two or more layers. If the phase difference film is a laminated film, the thermoplastic resins used to form each layer may be the same or different. Conventional known methods can be applied without particular limitation as the manufacturing method for the laminated film.

[0202] In addition to the cycloolefin resin, cellulose ester resin, and acrylic resin mentioned above, polycarbonate resin is preferably used as the thermoplastic resin for forming the phase difference film. In particular, polycarbonate resin is preferred when manufacturing the obliquely stretched film described later. When the phase difference film is made into a laminated film, for example, a combination of cellulose ester resin and a polycarbonate resin layer is preferred.

[0203] (Polycarbonate resin) Various polycarbonate resins can be used without particular limitations, but aromatic polycarbonate resins are preferred in terms of chemical properties and physical properties, and polycarbonates having a fluorene skeleton and bisphenol A-based polycarbonate resins are particularly preferred. Among these, those using bisphenol A derivatives obtained by introducing a benzene ring, a cyclohexane ring, and an aliphatic hydrocarbon group to bisphenol A are more preferred. Furthermore, polycarbonate resins with a structure that reduces intramolecular anisotropy, obtained using derivatives in which the above functional groups are introduced asymmetrically to the central carbon of bisphenol A, are particularly preferred.

[0204] Such polycarbonate resins are particularly preferred if they are obtained by replacing the two methyl groups on the central carbon of bisphenol A with benzene rings, or by asymmetrically substituting the hydrogen atoms at the positions of each benzene ring of bisphenol A with methyl groups, phenyl groups, etc. with respect to the central carbon. Specifically, these are obtained from 4,4′-dihydroxydiphenylalkanes or halogen-substituted derivatives thereof by the phosgene method or transesterification method, and examples include 4,4′-dihydroxydiphenylmethane, 4,4′-dihydroxydiphenylethane, and 4,4′-dihydroxydiphenylbutane. Furthermore, to give specific examples of polycarbonate resins, for instance, those described in Japanese Patent Publication No. 2006-215465, Japanese Patent Publication No. 2006-91836, Japanese Patent Publication No. 2005-121813, Japanese Patent Publication No. 2003-167121, Japanese Patent Publication No. 2009-126128, Japanese Patent Publication No. 2012-67300, and International Publication No. 2000 / 026705 are also examples.

[0205] (Manufacturing of phase difference films) Phase difference films can be manufactured by known molding methods such as molten casting, solution casting, and calendering, similar to the polarizing plate protective films described above. Molten casting and solution casting are preferred, with solution casting being particularly preferred.

[0206] Phase difference films can be manufactured using a resin and any additive in the solution casting method described for polarizing plate protective films, specifically in the step of obtaining the dope in (1). Furthermore, in the solution casting method described for polarizing plate protective films, the film substrate obtained in step (3) or (4) can be further obliquely stretched to produce a phase difference film using the following method.

[0207] To manufacture a long, obliquely stretched film using a film substrate, for example, an apparatus whose general configuration is schematically shown in Figures 5 and 6 is used. Figure 5 is a schematic plan view showing the general configuration of the obliquely stretched film manufacturing apparatus 80. Figure 6 is a schematic plan view showing an example of the rail pattern of the stretching section of the obliquely stretched film manufacturing apparatus 80. The manufacturing apparatus 80 comprises, in order from the upstream side in the conveying direction of the film substrate, a film feeding section 81, a conveying direction changing section 82, a guide roll 83, a stretching section 84, a guide roll 85, a conveying direction changing section 86, and a film winding section 87.

[0208] The film feeding unit 81 feeds the film substrate prepared as described above and supplies it to the stretching unit 84. The transport direction changing unit 82 changes the transport direction of the film substrate fed from the film feeding unit 81 toward the entrance of the stretching unit 84, which acts as an oblique stretching tenter. At least one guide roll 83 is provided upstream of the stretching unit 84 to stabilize the trajectory of the film substrate as it travels. At least one guide roll 85 is provided downstream of the stretching unit 84 to stabilize the trajectory of the film that has been obliquely stretched in the stretching unit 84 as it travels. The transport direction changing unit 86 changes the transport direction of the stretched film transported from the stretching unit 84 toward the film winding unit 87. The film winding unit 87 winds up the film transported from the stretching unit 84 via the transport direction changing unit 86.

[0209] Details of the stretching section 84 will be explained with reference to Figure 6. The manufacture of obliquely stretched film can be carried out, for example, using an obliquely stretchable tenter (oblique stretching machine) as shown in Figure 6, as the stretching section 84. This tenter is a device that heats the film substrate to any stretchable temperature and obliquely stretches it, and comprises a heating zone Z, a pair of rails Ri·Ro on the left and right, and a number of gripping devices Ci·Co (only one set of gripping devices is shown in Figure 6) that travel along the rails Ri·Ro to transport the film. Details of the heating zone Z will be described later. Each rail Ri·Ro is composed of multiple rail sections connected by connecting parts (white circles in Figure 6 are examples of connecting parts). The gripping devices Ci·Co consist of clips that grip both ends of the film in the width direction.

[0210] In Figure 6, the feeding direction D1 of the film substrate differs from the winding direction D2 of the long diagonally stretched film after stretching, forming a feeding angle θi between them. The feeding angle θi can be arbitrarily set to a desired angle within the range of greater than 0° and less than 90°.

[0211] Because the feed direction D1 and the winding direction D2 are different, the tenter's rail pattern has an asymmetrical shape on the left and right sides. Furthermore, the rail pattern can be adjusted manually or automatically according to the orientation angle θ and stretching ratio to be applied to the long obliquely stretched film to be manufactured. In the oblique stretching machine used in the manufacturing method of this embodiment, it is preferable that the positions of each rail section and rail connection section constituting the rails Ri and Ro can be freely set, and the rail pattern can be arbitrarily changed. This allows the orientation angle of the film to be freely set.

[0212] In the stretching section 84, the film substrate is gripped at both ends by left and right grippers Ci and Co, and is transported within the heating zone Z as the grippers Ci and Co move. The left and right grippers Ci and Co are positioned at the entrance of the stretching section 84 (position A in the figure) in a direction approximately perpendicular to the direction of film travel (feed-out direction D1), and travel on asymmetrical rails Ri and Ro, respectively, releasing the gripped film at the exit (position B in the figure) when stretching is complete. The film released from the grippers Ci and Co is wound onto a core in the film winding section 87 described above.

[0213] Because rails Ri and Ro are asymmetrical, in the example shown in Figure 6, the left and right grippers Ci and Co, which were facing each other at position A in the figure, will move in a positional relationship where the gripper Ci traveling on the Ri side (inner course side) will lead the gripper Co traveling on the Ro side (outer course side) as they travel along rails Ri and Ro.

[0214] In other words, at position A in the diagram, of the grippers Ci and Co which were facing each other in a direction approximately perpendicular to the film unwinding direction D1, when one gripper Ci reaches position B at the end of film stretching first, the line connecting grippers Ci and Co is inclined by an angle θL with respect to a direction approximately perpendicular to the film winding direction D2. Through this action, the film substrate is stretched obliquely at an angle of θL with respect to the width direction. Here, "approximately perpendicular" means within the range of 90 ± 1°.

[0215] The heating zone Z of the stretching section 84 consists of a preheating zone Z1, a stretching zone Z2, and a heat-setting zone Z3. In the stretching section 84, the film gripped by the gripping device Ci·Co passes through the preheating zone Z1, the stretching zone Z2, and the heat-setting zone Z3 in that order. In this embodiment, the preheating zone Z1 and the stretching zone Z2 are separated by a partition wall, and the stretching zone Z2 and the heat-setting zone Z3 are separated by a partition wall.

[0216] The preheating zone Z1 refers to the section at the entrance of the heating zone Z in which the gripping devices Ci·Co, which grip both ends of the film, travel while maintaining a constant distance between them (in the film width direction).

[0217] The stretching zone Z2 refers to the section where the distance between the gripping devices Ci·Co, which hold both ends of the film, begins to widen until it reaches a predetermined distance. This is how the diagonal stretching described above is performed. In other words, in stretching zone Z2, a diagonal stretching process is performed to obtain a diagonally stretched film by stretching a long film (film substrate) in a diagonal direction that is inclined with respect to both the width direction and the length direction within the film surface. Note that stretching in the longitudinal or transverse direction may be performed before or after the diagonal stretching as needed.

[0218] The heat-setting zone Z3 is the section after the stretching zone Z2 where the spacing between the gripping devices Ci and Co becomes constant again, and where the gripping devices Ci and Co at both ends remain parallel to each other as they travel. In other words, in the heat-setting zone Z3, a heat-setting process is performed in which the diagonally stretched film is conveyed while maintaining a constant width.

[0219] Furthermore, after the stretched film has passed through the heat-fixing zone Z3, it may also pass through a section (cooling zone) where the temperature within the zone is set to be below the glass transition temperature Tg (°C) of the thermoplastic resin constituting the film. In this case, considering the shrinkage of the film due to cooling, the rail pattern may be designed to narrow the distance between opposing grippers Ci·Co in advance.

[0220] It is preferable to set the temperature of the preheating zone Z1 to Tg to Tg+30°C, the temperature of the stretching zone Z2 to Tg to Tg+30°C, and the temperatures of the heat-fixing zone Z3 and the cooling zone to Tg-30 to Tg+20°C, relative to the glass transition temperature Tg of the thermoplastic resin.

[0221] The lengths of the preheating zone Z1, stretching zone Z2, and heat setting zone Z3 can be selected as appropriate. Typically, the length of the preheating zone Z1 is 100-150% of the length of the stretching zone Z2, and the length of the heat setting zone Z3 is typically 50-100%.

[0222] Furthermore, if the width of the film before stretching is Wo (mm) and the width of the film after stretching is W (mm), the stretching ratio R (W / Wo) in the stretching process is preferably 1.3 to 3.0, more preferably 1.5 to 2.8. A stretching ratio within this range is preferable because it reduces thickness unevenness in the width direction of the film. In the stretching zone Z2 of the oblique stretching tenter, if the stretching temperature is varied in the width direction, it is possible to further improve the thickness unevenness in the width direction. Note that the above stretching ratio R is equal to the ratio (W / Wo) when the distance Wo between the ends of the clips gripped at the tenter inlet becomes the distance W at the tenter outlet.

[0223] The thickness of the phase difference film can be determined as appropriate, but generally it is preferable to be in the range of 1 to 500 μm from the viewpoint of optical properties, strength, workability such as handling, and thin film properties. The thickness of the phase difference film is more preferably in the range of 5 to 100 μm, and even more preferably in the range of 15 to 80 μm.

[0224] [8] Manufacturing of polarizing plates The polarizer layer and the polarizer protective film, and the polarizer layer and the phase difference film are preferably bonded together, for example, via an adhesive layer described later. The adhesive layer may be a layer obtained by drying a water-based adhesive, or it may be a cured layer of an active-ray curable adhesive. Furthermore, the adhesive layer may contain a metal compound filler.

[0225] [Adhesive layer] The adhesive layer is optionally provided on the polarizing plate used in the present invention. Having an adhesive layer improves workability when manufacturing an organic EL display device in which the polarizing plate is bonded to the viewing side of an organic EL element. Figure 3 shows a cross-sectional view of the polarizing plate 10A, which is an example of a case where the polarizing plate has an adhesive layer. The polarizing plate 10A has the adhesive layer on the side opposite to the polarizer layer of the phase difference film.

[0226] The type of adhesive used to form the adhesive layer is not particularly limited, and examples include rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, and cellulose-based adhesives. Among these adhesives, acrylic-based adhesives are preferred because they exhibit excellent optical transparency, appropriate adhesion, cohesiveness, and bonding properties, and have excellent weather resistance and heat resistance. In the present invention, it is preferable to use an acrylic-based adhesive containing a (meth)acrylic polymer as the base polymer.

[0227] The method for forming the adhesive layer is not particularly limited and can be formed by methods commonly used in this field. Specifically, the adhesive layer can be formed by coating at least one side of a substrate with the adhesive or an adhesive composition containing its raw materials and a solvent, drying the coating film formed from the adhesive composition, or by irradiating with an active ray such as ultraviolet light. In the case of acrylic adhesives, the adhesive composition contains monomers that form the structural units of the polymer, polymerization initiators, and solvents.

[0228] The substrate to which the adhesive composition is applied is, for example, a release film or a phase difference film. When forming an adhesive layer on a release film, the formed adhesive layer is transferred to the phase difference film, and the release film is peeled off. The adhesive layer may be protected with a release film until the polarizing plate 10B is put into practical use.

[0229] The thickness of the adhesive layer is not particularly limited, but it is preferably about 10 to 75 μm, and more preferably about 12 to 50 μm.

[0230] [Adhesive layer] The polarizer layer and the polarizer protective film, and the polarizer layer and the phase difference film can be bonded together, for example, via an adhesive layer. The adhesive layer may be a layer obtained by drying a water-based adhesive, or it may be a cured layer of an active-ray curable adhesive. The adhesive layer may also contain a metal compound filler.

[0231] Examples of water-based adhesives include isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latex adhesives, water-based polyurethanes, and water-based polyesters. A specific example of a polyvinyl alcohol adhesive is a fully saponifiable polyvinyl alcohol aqueous solution (water glue). Examples of active-beam-curable adhesives include ultraviolet-curable adhesives and electron beam-curable adhesives.

[0232] [Other functional layers of polarizing plates] Another embodiment of the polarizing plate, as shown in polarizing plate 10B in Figure 2, has a hard coat layer, and is obtained by laminating the layers such that the hard coat layer 4, polarizing plate protective film 1, polarizer layer 2, and phase difference film 3 are arranged from the viewing side.

[0233] (Hard coat layer) The hard coat layer 4 preferably exhibits a hardness of "HB" or higher in the pencil hardness test specified in JIS K5600-2014, and it is preferable that it contains a cured product of an active-ray curable resin to obtain this hardness. As the active-ray curable resin, a component containing a monomer having an ethylenically unsaturated double bond is preferably used. Examples of active-ray curable resins include ultraviolet-curable resins and electron-beam-curable resins, but resins that harden by ultraviolet irradiation are preferred because they have excellent mechanical film strength (scratch resistance, pencil hardness).

[0234] Acrylic materials are preferably used as the active-ray curable resin. Suitable acrylic materials include monofunctional or polyfunctional (meth)acrylate compounds such as (meth)acrylic acid esters of polyhydric alcohols, and polyfunctional urethane (meth)acrylate compounds synthesized from diisocyanates and hydroxyesters of polyhydric alcohols and (meth)acrylic acid. In addition, polyether resins, polyester resins, epoxy resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, and others having acrylate-based functional groups can also be used.

[0235] In particular, UV-curable acrylate resins, UV-curable urethane acrylate resins, UV-curable polyester acrylate resins, UV-curable epoxy acrylate resins, UV-curable polyol acrylate resins, or UV-curable epoxy resins are preferably used, with UV-curable acrylate resins being the most preferred among them.

[0236] The hard coat layer is formed using, for example, a hard coat layer forming composition containing an active-ray curable resin, a polymerization initiator, and a solvent. The solvent included in the hard coat layer forming composition is preferably one that dissolves or swells the polarizing plate protective film or, if the polarizing plate protective film has a primer layer described later, the primer layer. By dissolving or swelling the polarizing plate protective film or primer layer with the solvent, the hard coat layer forming composition can easily penetrate from the surface into the interior of the polarizing plate protective film or primer layer, thereby improving the adhesion between the polarizing plate protective film or primer layer and the hard coat layer.

[0237] Furthermore, a layer is formed near the surface of the polarizing plate protective film or primer layer in which the resin components of the polarizing plate protective film or primer layer and the resin components of the hard coat layer are mixed. The action of this layer makes it possible to tilt the refractive index between the polarizing plate protective film or primer layer and the hard coat layer, thereby preventing interference unevenness.

[0238] Alternatively, for the composition for forming a hard coat layer, depending on the purposes such as increasing the hardness of the hard coat layer, suppressing curing shrinkage, preventing blocking, controlling the refractive index, imparting antiglare properties, and controlling the properties of the surface of the hard coat layer, conventionally known fine particles, dispersants, surfactants, antistatic agents, silane coupling agents, thickeners, anti-coloring agents, coloring agents (pigments, dyes), defoaming agents, leveling agents, flame retardants, adhesion imparting agents, polymerization inhibitors, antioxidants, surface modifiers, etc. may be added. Further, the composition for forming the hard coat layer may contain a photosensitizer, and specific examples thereof include n-butylamine, triethylamine, poly-n-butylphosphine, etc.

[0239] In particular, it is preferable that the hard coat layer contains fine particles. The content of the fine particles is preferably such that fine particles:actinic ray-curable resin = 100:100 to 400:100. By containing fine particles in such a content, dimensional fluctuations of the hard coat layer can be reduced. The fine particles here are not particularly limited, but are preferably fine particles composed of a metal oxide (hereinafter also referred to as "metal oxide particles"). Examples of the metal oxide here include silica, alumina, zirconia, titanium oxide, antimony pentoxide, etc. Among these, the metal oxide particles are preferably composed of silica. The silica fine particles may be hollow particles having cavities formed inside.

[0240] It is preferable that the above fine particles are coated with a polymer silane coupling agent. By coating the surface of the fine particles with a polymer silane coupling agent, the fine particles can be uniformly dispersed in the composition for forming a hard coat layer. The average particle diameter of the fine particles coated with the polymer silane coupling agent is preferably 5 to 500 nm, more preferably 10 to 200 nm. By using fine particles having such an average particle diameter, the optical properties of the hard coat layer can be enhanced.

[0241] The polymer silane coupling agent described above is prepared by reacting a polymerizable monomer with a silane coupling agent (reactive silane compound). Examples of polymerizable monomers include monomers having an ethylenically unsaturated double bond, and monomers selected from (meth)acrylic acid and its derivatives are preferred. As the reactive silane compound, hydrolyzable silane compounds in which three alkoxy groups and one functional group are bonded to a silicon atom are preferred. Examples of functional groups bonded to the silicon atom include groups having one or more groups selected from (meth)acryloxy groups, epoxy groups (glycide groups), urethane groups, amino groups, fluoro groups, and mercapto groups.

[0242] Polymer silane coupling agents can be prepared, for example, by following the method for producing a reaction product of a polymerizable monomer and a reactive silane compound disclosed in Japanese Patent Application Publication No. 11-116240. The number-average molecular weight of the polymer silane coupling agent is preferably 2,500 to 150,000 in terms of polystyrene, and more preferably 2,000 to 100,000.

[0243] A method for coating the surface of fine particles with a polymer silane coupling agent will be explained using silica fine particles as an example. First, a dispersion is prepared by dispersing silica fine particles and a polymer silane coupling agent in an organic solvent. Alkali is added to this dispersion to generate hydroxyl groups on the surface of the silica fine particles, and the polymer silane coupling agent is adsorbed onto these hydroxyl groups. Alternatively, the hydroxyl groups of the polymer silane coupling agent and the hydroxyl groups of the polymer silane coupling agent are bonded by a dehydration reaction. Finally, the silica fine particles to which the polymer silane coupling agent has been adsorbed or bonded are separated from the dispersion and dried to obtain silica fine particles coated with the polymer silane coupling agent.

[0244] The method for preparing the above-mentioned hard coat layer forming composition is not particularly limited, as long as the solid components contained in the hard coat layer can be uniformly mixed with the solvent. For example, the composition can be prepared by mixing or dissolving each of the solid components and the solvent using known equipment such as a paint shaker, bead mill, kneader, or mixer.

[0245] The hard coat layer forming composition is applied to the surface of a polarizing plate protective film or a primer layer, and a hard coat layer is formed by curing the active-ray curable resin in the coating film. Conventional known methods can be applied without particular limitation as the coating method for the hard coat layer forming composition. For example, when forming a uniform thin film layer, the microgravure coating method is preferred, and when it is necessary to form a thick film layer, the die coating method is preferred. After removing the solvent from the coating film as necessary, the hard coat layer is obtained by curing the active-ray curable resin by active-ray irradiation.

[0246] The thickness of the hard coat layer is preferably in the range of 0.01 to 20 μm as an average thickness, and preferably in the range of 0.5 to 10 μm.

[0247] (Primer layer) Any material that can improve the adhesion and bonding between the polarizing plate protective film and the hard coat layer or polarizer layer can be used as the material constituting the primer layer. In addition to adhesion and bonding, it is preferable that the material has excellent properties such as transparency and thermal stability. Examples of such materials include resins composed of polyurethane, polyolefin, polyester, polyvinylidene chloride, acrylic polymers, modified silicone polymers, styrene-butadiene rubber, carbodiimide compounds, isocyanates, etc.

[0248] The above-mentioned primer layer may also contain any additives as needed. Specific examples of additives include leveling agents, polymerization initiators, polymerization accelerators, viscosity modifiers, slip agents, dispersants, plasticizers, heat stabilizers, light stabilizers, lubricants, antioxidants, flame retardants, colorants, antistatic agents, compatibilizers, and crosslinking agents. The type and amount of additives used can be appropriately determined depending on the purpose. For example, the amount of additive used is preferably 30 parts by mass or less, and more preferably 20 parts by mass or less, per 100 parts by mass of total solids in the primer layer.

[0249] Among the resins mentioned above, those primarily composed of polyurethane are preferably used as the material constituting the primer layer. Specific examples of polyurethane include DIC Corporation's "Hydran Series" products AP-201, AP-40F, HW-140SF, and WLS-202; Daiichi Kogyo Seiyaku Co., Ltd.'s "Superflex Series" products SF-210, SF460, SF870, SF420, and SF-420NS; Mitsui Chemicals, Inc.'s "Takelac Series" products W-615, W6010, W-6020, W-6061, W-405, W-5030, W-5661, W-512A-6, W-635, WPB-6601, WS-6021, WS-5000, WS-5100, WS-4000, WSA-5920, and WF-764; and Adeka Corporation's development product "SPX-0882". Furthermore, resins such as polyurethanes that have carboxyl groups in their side chains can be crosslinked with crosslinking agents such as isocyanates, oxazolines, and carbodiimides to improve the strength of the primer layer.

[0250] [Optical properties of polarizing plates] In the polarizing plate used in the present invention, it is preferable that the light transmittance of the layer containing the dye compound (compound (D)) according to the present invention is within the following range.

[0251] (i) Light transmittance of the layer containing compound (D) The light transmittance of the layer containing compound (D) at a wavelength of 390 nm is preferably 9% or less, more preferably 7% or less, even more preferably 5% or less, and particularly preferably 3% or less. Having the light transmittance at 390 nm within this range is preferable because it allows for a higher degree of blocking of incident ultraviolet light, thereby significantly suppressing the degradation of the organic EL element.

[0252] Furthermore, the light transmittance of the layer containing compound (D) at a wavelength of 410 nm is preferably 60% or less, preferably 50% or less, and more preferably 40% or less. Having the light transmittance at a wavelength of 410 nm within the above range is preferable because it allows for a higher degree of blocking of incident ultraviolet light, thereby significantly suppressing the degradation of the organic EL element.

[0253] Furthermore, the light transmittance of the layer containing compound (D) at a wavelength of 430 nm is preferably 50% or more, preferably 60% or more, and more preferably 70% or more. Having the light transmittance at 430 nm within this range is preferable because it allows sufficient light emission from the organic EL element to be transmitted, ensuring sufficient display performance in the organic EL display device.

[0254] (ii) Light transmittance of polarizing plate In the polarizing plate used in the present invention, the light transmittance at a wavelength of 380 nm is preferably 9% or less, more preferably 7% or less, even more preferably 5% or less, and particularly preferably 3% or less. Furthermore, the light transmittance of the polarizing plate at a wavelength of 400 nm is preferably 20% or less, more preferably 15% or less, and more preferably 10% or less.

[0255] Because the light transmittance of the polarizing plate at a wavelength of 380 nm is within the above range, and the light transmittance at a wavelength of 400 nm is within the above range, incident ultraviolet light can be blocked to a higher degree. As a result, when the polarizing plate is used in an organic EL display device, incident ultraviolet light can be blocked to a higher degree.

[0256] In addition, the light transmittance of the polarizing plate used in the present invention at a wavelength of 450 nm is preferably 25% or more, more preferably 30% or more, and even more preferably 33% or more. When the light transmittance at a wavelength of 450 nm is within the above range, when used in an organic EL display device, the light emitted from the organic EL element can be sufficiently transmitted, and sufficient display performance can be ensured in the organic EL display device, which is preferable.

[0257] 〔9〕Organic EL display device The polarizing plate provided with the polarizing plate protection film of the present invention can be used in various display devices such as a liquid crystal display device (LCD), an organic EL display device (OLED), and a touch panel. In particular, it is preferable to use the polarizing plate according to the present invention as the circular polarizing plate of the organic EL display device.

[0258] A cross-sectional view of a configuration example of an organic EL display device provided with the polarizing plate protection film of the present invention is shown in FIG. 3. The organic EL display device 20 shown in FIG. 3 has an organic EL element 11 and the polarizing plate 10A or 10B according to the present invention on the viewing side thereof. The organic EL display element 11 has, for example, a light reflecting electrode, a light emitting layer, a transparent electrode layer, and a transparent plastic film substrate.

[0259] When the organic EL display device 20 is energized between the light reflecting electrode and the transparent electrode layer, the light emitting layer emits light and an image can be displayed. Further, since all the light incident from the outside to the organic EL display device is absorbed by the polarizer layer 2 of the polarizing plate 10A or 10B, even if it is reflected by the light reflecting electrode of the organic EL element 11, it does not exit to the outside, and the deterioration of the display characteristics due to the reflection of the background can be suppressed.

[0260] In the organic EL display device 20, it is preferable that the polarizing plate protection film contains the compound (D) and further contains an ultraviolet absorber.

[0261] In this way, by placing a polarizing plate equipped with a polarizing plate protective film containing a dye compound, antioxidant, and fine particles on the viewing side of the organic EL element, the polarizing plate can sufficiently absorb light with wavelengths shorter than the light-emitting region of the organic EL element (wavelengths longer than 430 nm), thereby protecting the organic EL element from external light. Furthermore, by arranging the polarizing plate protective film containing the dye compound, purple antioxidant, and fine particles in the specific order described above, the heat generated internally is more easily released to the outside from the surface of the polarizing plate protective film. This has the advantage of suppressing deterioration such as fluctuations in the optical value of the phase difference film and shrinkage of the polarizer layer due to the heat generated by compound (D) and the ultraviolet absorber. [Examples]

[0262] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the examples, the units "parts" or "%" are used, and unless otherwise specified, they represent "parts by mass" or "mass%".

[0263] Example 1 (Measurement of maximum absorption wavelength) The maximum absorption wavelength of the dye compound used in the examples (hereinafter referred to as compound (D)) was determined by measuring the absorption spectrum of the dye compound in chloroform using a UV-2450 ultraviolet-visible spectrophotometer manufactured by Shimadzu Corporation, and is shown in Table I. In the table, "compound 1" refers to the compound having the structure represented by Formula 1 according to the present invention.

[0264] In this invention, "maximum absorption wavelength" refers to the wavelength (nm) that exhibits the maximum and highest absorbance (absorption intensity) in the absorption spectrum of the compound obtained when the absorption spectrum of the above compound is measured.

[0265] [Table 1]

[0266] The structures of comparative compounds 1-3 listed in Table I are shown below.

[0267] [ka]

[0268] [1] Fabrication of polarizing plate protective film <Polarizing plate protective film 101: Fabrication of cycloolefin resin film> (Preparation of dope) A dope with the following composition was prepared. First, dichloromethane and ethanol were added to a pressurized dissolution tank. To the pressurized dissolution tank containing the mixed solution of dichloromethane and ethanol, a cycloolefin resin (COP): Arton G7810 (ARTON G7810, manufactured by JSR Corporation, Mw: 140,000, a cycloolefin resin having a carboxylic acid group) and compound 1 as compound (D) were added while stirring. Furthermore, 15 minutes after the start of solvent addition, the fine particle additive solution prepared below was added and heated to 80°C, and completely dissolved while stirring. At this time, the temperature was raised from room temperature by 5°C / min, dissolved in 30 minutes, and then cooled at 3°C / min. The obtained solution was filtered using Asaka Filter Paper No. 244 manufactured by Asaka Filter Paper Co., Ltd., and the dope was prepared.

[0269] (Composition of dope) COP(G7810) 100 parts by mass Dichloromethane 200 parts by mass 10 parts by mass of ethanol Compound (D): Compound 1 6 parts by mass

[0270] (Formation of polarizing plate protective film 101) The obtained dope was kept at 30°C and uniformly cast onto a stainless steel belt, which was a metal support maintained at 30°C. The cast dope was then dried until the residual solvent content reached 30% by mass, and then peeled off the stainless steel belt to obtain a film-like material.

[0271] Next, the obtained film was dried at 40°C until the residual solvent content was 10% by mass, and then stretched in the width direction at a stretching ratio of 1.4 times (40%). The obtained film was then further dried at 150°C while being transported by multiple rolls to obtain a polarizing plate protective film 101 with a length of 3000 m and a thickness of 20 μm.

[0272] <Preparation of polarizing plate protective film 102> Polarizing plate protective film 102 was prepared in the same manner as polarizing plate protective film 101, except that the following dope was used.

[0273] (Composition of dope) COP(G7810) 100 parts by mass Dichloromethane 200 parts by mass 10 parts by mass of ethanol Compound (D): Compound 1 6 parts by mass Antioxidant: Irganox 1076 (manufactured by BASF Japan Ltd.) 0.5 parts by mass

[0274] <Preparation of polarizing plate protective film 103> A polarizing plate protective film 103 was prepared in the same manner as the polarizing plate protective film 101, except that the following dope was used.

[0275] (Composition of dope) COP(G7810) 100 parts by mass Dichloromethane 200 parts by mass 10 parts by mass of ethanol Compound (D): Compound 1 6 parts by mass Antioxidant: Irganox 1076 (manufactured by BASF Japan Ltd.) 0.5 parts by mass Fine particles: Silicon dioxide dispersion (based on solid content) 1 part by mass

[0276] (Silicon dioxide dispersion) First, 10 parts by mass of Aerosil R812 (trade name, manufactured by Nippon Aerosil Co., Ltd.) and 90 parts by mass of ethanol were mixed and stirred in a dissolver for 30 minutes, and then silicon dioxide was dispersed in the ethanol using a Manton Gorin. 88 parts by mass of methylene chloride was added to this dispersion while stirring, and the dispersion was diluted by mixing in a dissolver for 30 minutes. This diluted dispersion was filtered using a fine particle dispersion diluent filter (Advantec Toyo Co., Ltd.: polypropylene wind cartridge filter TCW-PPS-1N) to obtain a silicon dioxide dispersion.

[0277] <Fabrication of polarizing plate protective film 104> A polarizing plate protective film 104 was prepared in the same manner as the polarizing plate protective film 101, except that the following dope was used.

[0278] (Composition of dope) COP(G7810) 100 parts by mass Dichloromethane 200 parts by mass 10 parts by mass of ethanol Compound (D): Compound 1 6 parts by mass Fine particles: Silicon dioxide dispersion (based on solid content) 1 part by mass

[0279] <Preparation of polarizing plate protective films 105-107> Polarizing plate protective films 105 to 107 were prepared in the same manner as polarizing plate protective films 102 to 104, except that the antioxidant listed in Table II was changed to Irganox 1010 (manufactured by BASF Japan Ltd.) and the fine particles were changed to R972.

[0280] <Preparation of polarizing plate protective film 108: Preparation of cellulose ester resin film> (Preparation of dope) A dope with the following composition was prepared. First, dichloromethane and ethanol were added to a pressurized dissolution tank. Then, cellulose ester was added to the pressurized dissolution tank containing the solvent while stirring, and the mixture was heated and stirred until completely dissolved.

[0281] (Composition of dope) Triacetylcellulose (TAC: acetyl cellulose with 2.8 acetyl substitution degrees, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) 95 parts by mass Polycondensed ester compound N 2 parts by mass Polycondensed ester compound M: 7 parts by mass Dichloromethane 540 parts by mass Ethanol 35 parts by mass Compound (D): Compound 1 6 parts by mass

[0282] Furthermore, the above additive components were placed in a sealed container, dissolved while stirring, and filtered using Asaka Filter Paper No. 244 manufactured by Asaka Filter Paper Co., Ltd. to prepare the dope.

[0283] Polycondensed ester compound N and polycondensed ester compound M were prepared as follows.

[0284] (Ester compound N) First, 251 g of 1,2-propylene glycol, 354 g of terephthalic acid, 680 g of p-troylic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were placed in a 2 L four-necked flask equipped with a thermometer, stirrer, and condenser. Next, a stream of nitrogen gas was blown into the four-necked flask, and the solution was gradually heated while stirring until the solution temperature reached 230°C, allowing the dehydration condensation reaction to proceed while observing the degree of polymerization. After the reaction was complete, the unreacted 1,2-propylene glycol was removed by reduced-pressure distillation at 200°C to obtain the polycondensed ester compound N. This ester compound N had an acid value of 0.30 and a number-average molecular weight of 400.

[0285] (Ester compound M) First, 251 g of 1,2-propylene glycol, 244 g of phthalic anhydride, 103 g of adipic acid, 610 g of benzoic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were placed in a 2 L four-necked flask equipped with a thermometer, stirrer, and condenser. Next, a stream of nitrogen gas was blown into the four-necked flask, and the solution was gradually heated while stirring until the solution temperature reached 230°C, allowing the dehydration condensation reaction to proceed while observing the degree of polymerization. After the reaction was complete, the unreacted 1,2-propylene glycol was removed by distillation under reduced pressure at 200°C to obtain the polycondensed ester compound M. This ester compound M had an acid value of 0.10 and a number-average molecular weight of 450.

[0286] (Film formation of polarizing plate protective film 108) The dope prepared above was uniformly cast onto a stainless steel band support at a temperature of 22°C and a width of 1.8 m using a belt casting apparatus. The solvent was evaporated from the stainless steel band support until the residual solvent content was 20%, and the doped film (web) was peeled off from the stainless steel band support.

[0287] Next, the peeled web was desoldered at 35°C, slit into 1.6 m widths, and then stretched to 1.1 times its original width in the TD direction at 160°C using a tenter stretcher. At this time, the amount of residual solvent at the start of stretching with the tenter was 4% by mass.

[0288] Subsequently, the film was dried by transporting it through drying zones at 120°C and 140°C using numerous rollers. After that, it was slit to a width of 1.3m, knurling was applied to both ends of the film to a width of 10mm and a height of 2.5μm, and then it was wound onto a core to produce polarizing plate protective film 108. The film thickness of polarizing plate protective film 108 was 25μm, and the length of the winding was 6000m.

[0289] <Preparation of polarizing plate protective film 109> Polarizing plate protective film 109 was prepared in the same manner as polarizing plate protective film 108, except that the following dope was used.

[0290] (Composition of dope) Triacetylcellulose (TAC: acetylcellulose with 2.8 degrees of acetyl substitution, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) 95 parts by mass Polycondensed ester compound N 2 parts by mass Polycondensed ester compound M: 7 parts by mass Dichloromethane 540 parts by mass Ethanol 35 parts by mass Compound (D): Compound 1 6 parts by mass Antioxidant: Irganox 1076 (manufactured by BASF Japan Ltd.) 0.5 parts by mass

[0291] <Preparation of polarizing plate protective film 110> Polarizing plate protective film 110 was prepared in the same manner as polarizing plate protective film 108, except that the following dope was used.

[0292] (Composition of dope) Triacetylcellulose (TAC: acetylcellulose with 2.8 degrees of acetyl substitution, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) 95 parts by mass Polycondensed ester compound N 2 parts by mass Polycondensed ester compound M: 7 parts by mass Dichloromethane 540 parts by mass Ethanol 35 parts by mass Compound (D): Compound 1 6 parts by mass Antioxidant: Irganox 1076 (manufactured by BASF Japan Ltd.) 0.5 parts by mass Fine particles (R812): Silicon dioxide dispersion (based on solid content) 1 part by mass

[0293] <Preparation of polarizing plate protective film 111> Polarizing plate protective film 111 was prepared in the same manner as polarizing plate protective film 108, except that the following dope was used.

[0294] (Composition of dope) Triacetylcellulose (TAC: acetylcellulose with 2.8 degrees of acetyl substitution, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) 95 parts by mass Polycondensed ester compound N 2 parts by mass Polycondensed ester compound M: 7 parts by mass Dichloromethane 540 parts by mass Ethanol 35 parts by mass Compound (D): Compound 1 6 parts by mass Fine particles (R812): Silicon dioxide dispersion (based on solid content) 1 part by mass

[0295] <Polarizing plate protective film 112: Fabrication of acrylic resin film> A dope with the following composition was prepared. First, dichloromethane and ethanol were added to a pressurized dissolution tank. Next, the resin was added to the pressurized dissolution tank while stirring. Then, the rubber particle dispersion prepared below was added and dissolved completely while stirring. This was filtered using an SHP150 manufactured by Rokitechno Co., Ltd. to obtain the dope.

[0296] (Composition of dope) Resin ((meth)acrylic resin: Ac) 95 parts by mass Dichloromethane 200 parts by mass Compound (D): Compound 1 6 parts by mass Rubber particle dispersion 200 parts by mass

[0297] The (meth)acrylic resin used above is methyl methacrylate (MMA) / N-phenylmaleimide (PMI) / butyl acrylate (BA copolymer (80 / 10 / 10 mass ratio), Tg: 120°C, Mw: 2 million).

[0298] The glass transition temperature (Tg) of the acrylic resin was measured using DSC (Differential Scanning Colorimetry) in accordance with JIS K7121-2012.

[0299] Furthermore, the weight-average molecular weight (Mw) of the acrylic resin was measured using gel permeation chromatography (HLC8220GPC, Tosoh Corporation) and columns (TSK-GELG6000HXL-G5000HXL-G5000HXL-G4000HXL-G3000HXL in series, Tosoh Corporation). 20 mg ± 0.5 mg of the sample was dissolved in 10 mL of tetrahydrofuran and filtered through a 0.45 mm filter. 100 mL of this solution was injected into the column (at 40°C), and the value was measured at a detector RI temperature of 40°C, with the value converted to styrene equivalent being used.

[0300] The rubber particle dispersion used above was obtained by mixing 10 parts by mass of acrylic rubber particles M-210 (core: multilayer acrylic rubber polymer, shell: methacrylate ester polymer mainly composed of methyl methacrylate, Tg of acrylic rubber polymer: approximately -10°C, average particle diameter: 220 nm) and 190 parts by mass of dichloromethane in a dissolver for 50 minutes, and then dispersing them using a Milder disperser (manufactured by Taiheiyo Kiko Co., Ltd.) under conditions of 1500 rpm.

[0301] The average particle size of the rubber particles was obtained by measuring the dispersed particle size of the rubber particles in the dispersion using a zeta potential / particle size measurement system (ELSZ-2000ZS, manufactured by Otsuka Electronics Co., Ltd.).

[0302] <Preparation of polarizing plate protective film 113> A polarizing plate protective film 113 was prepared in the same manner as the polarizing plate protective film 112, except that the following dope was used.

[0303] (Composition of dope) Resin ((meth)acrylic resin: Ac) 95 parts by mass Dichloromethane 200 parts by mass Compound (D): Compound 1 6 parts by mass Rubber particle dispersion 200 parts by mass Antioxidant: Irganox 1076 (manufactured by BASF Japan Ltd.) 0.5 parts by mass

[0304] <Fabrication of polarizing plate protective film 114> A polarizing plate protective film 114 was prepared in the same manner as the polarizing plate protective film 112, except that the following dope was used.

[0305] (Composition of dope) Resin ((meth)acrylic resin: Ac) 95 parts by mass Dichloromethane 200 parts by mass Compound (D): Compound 1 6 parts by mass Rubber particle dispersion 200 parts by mass Antioxidant: Irganox 1076 (manufactured by BASF Japan Ltd.) 0.5 parts by mass Fine particles (R812): Silicon dioxide dispersion (based on solid content) 1 part by mass

[0306] <Preparation of polarizing plate protective film 115> A polarizing plate protective film 115 was prepared in the same manner as the polarizing plate protective film 112, except that the following dope was used.

[0307] (Composition of dope) Resin ((meth)acrylic resin: Ac) 95 parts by mass Dichloromethane 200 parts by mass Compound (D): Compound 1 6 parts by mass Rubber particle dispersion 200 parts by mass Fine particles (R812): Silicon dioxide dispersion (based on solid content) 1 part by mass

[0308] <Preparation of polarizing plate protective films 116-127> Polarizing plate protective films 101-104 and 108-115 were prepared in the same manner as above, except that compound (D): compound 1 was changed to comparative compounds 1, 2, and 3.

[0309] [2] Fabrication of polarizing plates <Fabrication of the polarizer layer> A 25 μm thick polyvinyl alcohol-based film was swollen with water at 35°C. The resulting film was immersed for 60 seconds in an aqueous solution consisting of 0.075 g of iodine, 5 g of potassium iodide, and 100 g of water, and then further immersed in an aqueous solution at 45°C consisting of 3 g of potassium iodide, 7.5 g of boric acid, and 100 g of water. The resulting film was uniaxially stretched at a stretching temperature of 55°C and a stretching ratio of 5 times. After washing the uniaxially stretched film with water, it was dried to obtain a polarizer layer with a thickness of 12 μm.

[0310] <Preparation of phase difference film> Polycarbonate resin film (PC film) was manufactured using the following manufacturing method (melt casting method).

[0311] Polymerization was carried out using a batch polymerization apparatus consisting of two vertical reactors equipped with stirring blades and reflux condensers controlled to 100°C. 9,9-[4-(2-hydroxyethoxy)phenyl]fluorene (BHEPF), isosorbide (ISB), diethylene glycol (DEG), diphenyl carbonate (DPC), and magnesium acetate tetrahydrate were combined in molar ratios of BHEPF / ISB / DEG / DPC / magnesium acetate = 0.348 / 0.490 / 0.162 / 1.005 / 1.00 × 10⁻¹⁰ -5 The reactor was prepared in the following manner. After thoroughly purging the reactor with nitrogen (oxygen concentration 0.0005-0.001 vol%), it was heated with a heat transfer medium, and stirring was started when the internal temperature reached 100°C. Forty minutes after the start of heating, the internal temperature was raised to 220°C, and while controlling the temperature to maintain this level, the pressure was reduced to 13.3 kPa 90 minutes after reaching 220°C. The phenol vapor produced as a by-product of the polymerization reaction was led to a reflux condenser at 100°C, the monomer components contained in small amounts in the phenol vapor were returned to the reactor, and the non-condensing phenol vapor was led to a condenser at 45°C for recovery.

[0312] Nitrogen was introduced into the first reactor to restore pressure to atmospheric pressure, and then the oligomerized reaction solution in the first reactor was transferred to the second reactor. Next, heating and depressurization were started in the second reactor, and the internal temperature was raised to 240°C and the pressure to 0.2 kPa in 50 minutes. Polymerization was then allowed to proceed until the predetermined stirring power was reached. Once the predetermined power was reached, nitrogen was introduced into the reactor to restore pressure, the reaction solution was extracted in strand form, and pelletized using a rotary cutter to obtain polycarbonate resin A with a copolymer composition of BHEPF / ISB / DEG = 34.8 / 49.0 / 16.2 [mol%]. The reduced viscosity of this polycarbonate resin A was 0.430 dL / g, and the glass transition temperature was 138°C.

[0313] The obtained polycarbonate resin A was vacuum-dried at 80°C for 5 hours. Then, a polycarbonate resin film (PC film 1) with a thickness of 130 μm was produced as a long film roll (film roll) using a film manufacturing apparatus equipped with a single-screw extruder (manufactured by Isuzu Chemical Machinery Co., Ltd., screw diameter 25 mm, cylinder setting temperature: 220°C), a T-die (width 900 mm, setting temperature: 220°C), a chill roll (setting temperature: 120~130°C), and a winding machine.

[0314] The roll of PC film 1 prepared as described above was set in the obliquely stretched film manufacturing apparatus 80 (see Figures 5 and 6) and the PC film 1 was unwound. Then, the PC film 1 was passed through the preheating zone Z1 of the stretching section to heat it to the preheating temperature, then passed through the stretching zone Z2 to be obliquely stretched at a stretching ratio of 3, and subsequently passed through the heat-setting zone Z3 to produce an obliquely stretched PC film (λ / 4 sheet) with a film thickness of 50 μm, a width of 1500 mm, and an orientation angle θ = 45° (value at the center of the width). The produced obliquely stretched PC film was wound up to form a film roll. The temperature T1 (preheating temperature) of the preheating zone Z1 in the stretching section was set to (Tg + 15) °C, the temperature T2 (stretching temperature) of the stretching zone Z2 was set to (Tg + 11) °C, and the temperature T3 of the heat-setting zone Z3 was set to (Tg + 9) °C.

[0315] <Fabrication of polarizing plates> Polarizing plates 101 to 127 were fabricated by laminating the polarizing plate protective films 101 to 127, the polarizer layer, and the phase difference film in the order described above. The gaps between the phase difference film and the polarizer layer, and between the polarizing plate protective film and the polarizer layer, were bonded using a fully saponifiable polyvinyl alcohol aqueous solution (water-based adhesive).

[0316] ≪Rating≫ <1> Lightfastness test Lightfastness tests were conducted on the polarizing plate protective films 101 to 127 prepared as described above.

[0317] The polarizing plate protective film that was fabricated was covered with a xenon lamp (60W / m 2 The thin film was continuously irradiated with light for 100 hours, and the absorbance of the thin film before irradiation (0 hours) and after irradiation (100 hours) was measured using a spectrophotometer. The remaining dye rate of compound (D) was then measured according to the following formula (R).

[0318] Formula (R) Dye residual rate (%)={(A 100 ) / (A0)}×100 (However, A0 is the absorbance before irradiation with a xenon lamp, A 100 (This is the absorbance after irradiation with a xenon lamp.)

[0319] "Absorbance" refers to the absorbance of each compound at its maximum absorption wavelength. A higher dye retention rate indicates that the compound is less susceptible to degradation by light and therefore has higher lightfastness. Lightfastness was evaluated according to the following criteria.

[0320] A: Pigment retention rate of 65% or more B: Pigment retention rate is 40% or more, but less than 65%. C: Pigment retention rate is 10% or more, but less than 40%. D: Pigment retention rate is less than 10%

[0321] <2> Durability: Bleed-out evaluation Each polarizing plate protective film was left in a high-temperature, high-humidity atmosphere of 60°C and 90%RH for 1000 hours. After that, the presence or absence of bleed-out (crystal deposition) on the surface of the polarizing plate protective film was visually observed, and the bleed-out was evaluated according to the criteria described below.

[0322] ◎: No bleed-out is observed on the surface of the polarizing plate protective film. ○: Slight partial bleed-out is observed on the surface of the polarizing plate protective film. △: Slight bleed-out is observed across the entire surface of the polarizing plate protective film. ×: Clear bleed-out is observed across the entire surface of the polarizing plate protective film.

[0323] <3> Evaluation of light transmittance The light transmittance of the polarizing plate protective film prepared as described above was measured at different wavelengths (390 nm, 410 nm, and 430 nm) using a spectrophotometer (Hitachi High-Tech Science U-3300). The results are shown in Table II.

[0324] The configuration and evaluation results of the polarizing plate protective film are shown in Table II.

[0325] [Table 2]

[0326] From the evaluation results of the fabricated polarizer protective films shown in Table II, it can be seen that the polarizer protective films 101 to 115 using the dye compound according to the present invention have excellent light resistance and bleed-out properties, as well as excellent light transmittance reduction on the short wavelength side of visible light.

[0327] Furthermore, it was found that adding antioxidants and fine particles in addition to the dye compound further improves the light transmittance controllability of the polarizing plate protective film of the present invention.

[0328] Example 2 Using the polarizing plate protective films 101 to 127 prepared in Example 1, a primer layer was formed, a hard coat layer was formed, and an adhesive layer was applied to the side of the phase difference film opposite to the polarizer layer. An organic EL display device was then fabricated by laminating it with an organic EL element.

[0329] (1) Formation of the primer layer (Preparation of the primer coating solution for the hard coat layer) 100 parts by mass of a thermosetting water-based polyolefin resin (Arrowbase SB-1200 (product name), solids content 25%, manufactured by Unitika Ltd.) and 8 parts by mass of an oxazoline crosslinking agent (WS-700, manufactured by Nippon Shokubai Co., Ltd.) were diluted with a diluent (water / methanol = 30 / 70 (mass%)) until the solids content concentration was 5%, and then stirred at room temperature to prepare primer layer coating solution 1.

[0330] (Formation of primer layer on the hard coat side) The primer layer coating solution 1 prepared above was applied to the side of the polarizer protective films 101-127 opposite to the polarizer layer using a bar coater, and the film was formed by drying in an 80°C drying oven for 40 seconds, thereby forming a hard coat layer-side primer layer with a dry film thickness of 0.4 μm.

[0331] (2) Formation of the hard coat layer (Preparation of a composition for forming a hard coat layer) Hard coat resin; Pentaerythritol tri / tetraacrylate (NK Ester A-TMM-3L, trade name, manufactured by Shin Nakamura Chemical Industry Co., Ltd.) 100 parts by mass Photopolymerization initiator; Irgacure 184 (product name, manufactured by BASF Japan Ltd.) 9 parts by mass solvent; 20 parts by mass of propylene glycol monomethyl ether 30 parts by mass of methyl acetate Methyl ethyl ketone 70 parts by mass Additives; Surfactant; KF-351A (product name, polyether-modified silicone oil, manufactured by Shin-Etsu Chemical Co., Ltd.) 2 parts by mass Fine particles; 100 parts by mass of polymer silane coupling agent-coated silica

[0332] (Preparation of fine particles) The polymer silane coupling agent-coated silica described above was prepared as follows: 30 mL of methyl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd.: Light Ester M), 1 mL of 3-mercaptopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.: KBM-803), 100 mL of tetrahydrofuran as a solvent, and 50 mg of azoisobutyronitrile (manufactured by Kanto Chemical Co., Ltd.: AIBN) as a polymerization initiator were added to a container. After purging with N2 gas, the mixture was heated at 80°C for 3 hours to prepare the polymer silane coupling agent. The molecular weight of the obtained polymer silane coupling agent was 16000. The molecular weight was measured using a gel permeation chromatography apparatus.

[0333] Next, silica sol (manufactured by JGC Catalysts & Chemicals Co., Ltd.: Si-45P, trade name, SiO2 concentration 30% by mass, average particle size 45 nm, dispersion medium: water) was ion-exchanged using an ion-exchange resin, and the water was replaced with ethanol by ultrafiltration to prepare 100 g of an ethanol dispersion of silica fine particles (SiO2 concentration 30% by mass).

[0334] 100 g of this silica microparticle ethanol dispersion and 1.5 g of polymer silane coupling agent were dispersed in 20 g (25 mL) of acetone. 20 mg of 29.8% by mass aqueous ammonia was added to this mixture, and the mixture was stirred at room temperature for 30 hours to adsorb the polymer silane coupling agent onto the silica microparticles.

[0335] Subsequently, silica particles with an average particle size of 5 μm were added and stirred for 2 hours to adsorb any unadsorbed polymer silane coupling agent in the solution onto the silica particles. Then, the silica particles with an average particle size of 5 μm that had adsorbed the unadsorbed polymer silane coupling agent were removed by centrifugation. 1000 g of ethanol was added to the silica microparticle dispersion containing the adsorbed polymer silane coupling agent to allow the silica microparticles to settle. These were then separated, dried under reduced pressure, and dried at 25°C for 8 hours to obtain polymer silane coupling agent-coated silica. The average particle size of the obtained polymer silane coupling agent-coated silica was 57 nm. The average particle size was measured using a laser particle size analyzer.

[0336] (Formation of the hard coat layer) On the primer layer of the polarizing plate protective film with the primer layer prepared above, the hard coat layer forming composition prepared above was applied using a bar coater to a dry film thickness of 2.5 μm, and the solvent was evaporated by drying in a 50°C drying oven for 40 seconds. Then, while purging with nitrogen to maintain an oxygen concentration of 1.0 volume or less, an irradiation intensity of 100 mW / cm² was achieved using a UV lamp. 2 The irradiation dose is 0.2 J / cm². 2 The coating layer was then cured to produce a polarizing plate protective film with a hard coat layer.

[0337] (3) Fabrication of organic EL display devices In the same manner as in Example 1, polarizers were fabricated using the above-mentioned hard-coat polarizer protective film, polarizer layer, and phase difference film. The polarizers and organic EL elements were then bonded to each other via an adhesive layer obtained by peeling off the following release films, and organic EL display devices 201 to 227 were fabricated and evaluated.

[0338] Specifically, a Samsung GALAXY S10 (product name) equipped with an organic EL panel was disassembled, the circular polarizer was peeled off from the organic EL element, and polarizers 101 to 127 were bonded to the peeled surface via an adhesive layer, with the hard coat layer side facing the viewing side and the phase difference film side facing the organic EL element, thereby fabricating an organic EL display device.

[0339] (Preparation of adhesive composition) A monomer mixture consisting of 78 parts by mass of 2-ethylhexyl acrylate (2EHA), 18 parts by mass of N-vinyl-2-pyrrolidone (NVP), and 15 parts by mass of 2-hydroxyethyl acrylate (HEA) was mixed with 0.035 parts by mass of 1-hydroxycyclohexyl phenyl ketone (trade name: Irgacure 184, manufactured by BASF Japan Ltd.) and 0.035 parts by mass of 2,2-dimethoxy-1,2-diphenylethane-1-one (trade name: Irgacure 651, manufactured by BASF Japan Ltd.) as photopolymerization initiators. The mixture was then irradiated with ultraviolet light until the viscosity (measurement conditions: BH viscometer No. 5 rotor, 10 rpm, measurement temperature 30°C) reached approximately 20 Pa·s, thereby obtaining a prepolymer composition (polymerization rate: 8%) in which a portion of the above monomer components had polymerized. Next, 0.15 parts by mass of hexanediol diacrylate (HDDA) and 0.3 parts by mass of a silane coupling agent (product name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) were added to the prepolymer composition and mixed to obtain acrylic adhesive composition (a).

[0340] To the obtained acrylic adhesive composition (a), 0.2 parts by mass of bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (trade name: Irgacure 819, manufactured by BASF Japan Ltd.) was added (100 parts by mass of monomer components that form an acrylic polymer) and stirred to obtain an adhesive composition.

[0341] (Formation of the adhesive layer) An adhesive composition was applied to a phase difference film so that the thickness of the adhesive layer after formation was 150 μm. Then, a release film was bonded to the surface of the adhesive composition layer. After that, the illuminance was 6.5 mW / cm². 2 , Light amount: 1500mJ / cm 2 The adhesive composition layer was photocured by UV irradiation at a peak wavelength of 350 nm to form an adhesive layer.

[0342] ≪Rating≫ <4> Evaluation of luminescence loss Light transmittance was measured using a spectrophotometer (Hitachi High-Tech Science U-3300) in accordance with JIS K 7375:2008 "Plastics - Method for determining total light transmittance and total light reflectance". A value of 85% or higher was marked with "◎", 80% or higher but less than 85% was marked with "〇", and less than 80% was marked with "△". A light transmittance of 80% or higher indicates low luminescence loss.

[0343] <5> Lightfastness Test A lightfastness test was conducted on the organic EL display device fabricated as described above.

[0344] The fabricated organic EL display device was equipped with a xenon lamp (60W / m²). 2 The light from () was continuously irradiated for 100 hours, and the luminescence intensity before irradiation (0 hours) and after irradiation (100 hours) was measured. The change in luminescence intensity was then measured according to Equation 2 below.

[0345] Luminous intensity was measured at room temperature (25°C) at 2.5 mA / cm². 2 The luminescence of each organic EL display device was measured using a spectroradiometer CS-2000 (manufactured by Konica Minolta, Inc.) after the devices were lit under constant current density conditions.

[0346] Equation 2: Rate of change in luminous intensity (%) = {(A 100 ) / (A0)}×100 (However, A0 is the luminescence before irradiation with a xenon lamp, A 100 This represents the luminescence after irradiation with a xenon lamp. Furthermore, a higher value for "luminous intensity change rate" indicates greater light resistance of the display element. Light resistance was evaluated according to the following criteria.

[0347] A: Luminous intensity change rate is 90% or more B: Luminous intensity change rate is 80% or more, but less than 90%. C: Luminous intensity change rate is 70% or more, but less than 80%. D: Luminous intensity change rate is less than 70% The above layer configuration and evaluation results are shown in Table III below.

[0348] [Table 3]

[0349] The evaluation results shown in Table III indicate that the organic EL display devices 201-215 using the polarizing plate protective film of the present invention do not experience light loss and exhibit excellent light resistance of the display elements.

[0350] Furthermore, considering the evaluation results shown in Tables II and III, it was confirmed that the polarizing plate protective film of the present invention can protect the display element from external light, does not cause light emission loss to the display element, does not bleed out, and is a polarizing plate protective film with excellent light resistance, thus providing a polarizing plate and organic EL display device with excellent functionality and durability.

[0351] Example 3 <Preparation of polarizing plate protective film 301> (Support) A polyethylene terephthalate film (PET film): (TN100 manufactured by Toyobo Co., Ltd., with a release layer containing a non-silicone release agent, thickness 38 μm) was used as the support.

[0352] (Preparation of coating solution for polarizing plate protective film 301) The following components were mixed to obtain a coating solution for the base film 301.

[0353] First, dichloromethane and ethanol were added to a pressurized dissolution tank. Cycloolefin resin (COP) was added to the pressurized dissolution tank containing the mixed solution of dichloromethane and ethanol while stirring. Furthermore, 15 minutes after the start of solvent addition, the fine particle dispersion prepared above and compound (D): compound 1 were added, and the mixture was heated to 80°C and stirred until completely dissolved. At this time, the temperature was raised from room temperature by 5°C / min, dissolved in 30 minutes, and then cooled by 3°C / min. The obtained solution was filtered using Asaka Filter Paper No. 244 manufactured by Asaka Filter Paper Co., Ltd. to prepare a coating solution for polarizing plate protective film 301.

[0354] (Composition of the coating solution) COP(G7810) 100 parts by mass Dichloromethane 200 parts by mass 10 parts by mass of ethanol Compound (D): Compound 1 6 parts by mass Antioxidant: Irganox 1076 (manufactured by BASF Japan Ltd.) 0.5 parts by mass Fine particles (R812): Silicon dioxide dispersion, 1 part by mass

[0355] (Preparation of polarizing plate protective film 301) Using the coating apparatus shown in Figure 4, the coating solution for the polarizing plate protective film 301 was applied to the release layer of the support using a die by the backcoat method. Then, the base film was dried in the drying steps described below to form a polarizing plate protective film with a thickness of 5 μm, thereby obtaining the polarizing plate protective film 301.

[0356] Step 1: 1 minute at 40°C Step 2: Bake at 70°C for 1 minute Step 3: Bake at 100°C for 1 minute Step 4: Bake at 130°C for 2 minutes

[0357] <Preparation of polarizing plate protective film 302> In the preparation of the polarizing plate protective film 301, a coating solution for the polarizing plate protective film 301 was applied using a die by the backcoat method, and then the base film was dried in the drying step to produce a polarizing plate protective film with a thickness of 10 μm.

[0358] <Fabrication of polarizing plate protective film 303> A resin composition was obtained by mixing 100 parts by mass of cycloolefin resin (Zeonor, manufactured by Nippon Zeon Co., Ltd., with a glass transition temperature Tg = 126°C) and 6 parts by mass of the following compound (a2) using a twin-screw extruder.

[0359] Next, a single-screw extruder equipped with a gear pump and a filter was prepared, and the resin composition was fed into this single-screw extruder and melted. The molten resin composition was passed through the gear pump and then the filter, extruded from the T-die, and passed through a cooling roll to obtain a polarizing plate protective film 303 with a thickness of 10 μm.

[0360] (Synthesis of compound (a2): 6-(5-methylcarbonyloxyethyl-2H-benzotriazol-2-yl)benzo[1,3]dioxol-5-ol)

[0361] [ka]

[0362] A 200 mL four-necked flask was fitted with a ball-type condenser, thermometer, and stirrer. 2.0 g (0.0067 mol) of 6-(5-hydroxyethyl-2H-benzotriazole-2-yl)benzo[1,3]dioxol-5-ol, 50 mL of toluene, 1.6 g (0.0266 mol) of acetic acid, and 0.1 g (0.0010 mol) of methanesulfonic acid were added, and the mixture was refluxed at 110-115°C for 4 hours. The mixture was washed three times with 50 mL of warm water, 0.1 g of activated carbon was added, and the mixture was decolorized by refluxing and stirring. The mixture was filtered while still hot, the precipitated crystals were filtered, washed with 10 mL of toluene, and dried at 60°C to obtain 2.2 g of compound (a2). The yield from 6-(5-hydroxyethyl-2H-benzotriazole-2-yl)benzo[1,3]dioxol-5-ol was 96%.

[0363] Furthermore, when the ultraviolet-visible absorption spectrum of compound (a2) was measured, the maximum absorption wavelength was found to be 368 nm.

[0364] The obtained polarizing plate protective films were used to evaluate light resistance and durability (bleed-out) in the same manner as in Example 1. For the evaluation, the polarizing plate protective films 301 and 302 were used with the support removed.

[0365] Thin polarizer protective films 301 and 302 exhibited excellent light resistance ("A") and durability (bleed-out: "◎"), indicating that the effects of the present invention can be obtained even with thin polarizer protective films. On the other hand, polarizer protective film 303 had excellent light resistance, but when 10 film samples were evaluated, the bleed-out evaluation was in the range of "△~○", indicating somewhat inferior durability. [Industrial applicability]

[0366] The polarizing plate protective film of the present invention is a polarizing plate protective film containing a resin and a dye compound, which can protect the display element from external light, does not cause light emission loss to the display element, does not bleed out, and has excellent light resistance, making it suitable for use in display devices, particularly organic electroluminescent display devices. [Explanation of Symbols]

[0367] 10A, 10B polarizing plate 1. Polarizing plate protective film 2 Polarizer layer 3 Phase difference film 4. Hard court layer 5. Adhesive layer 20 Organic EL display device 11 Organic EL elements 80. Manufacturing equipment for obliquely stretched film 81 Film advance mechanism 82, 86 Conveying direction changing section 83, 85 Guide Roll 84 Stretching section 87 Film winding section B200 manufacturing equipment B210 Supply section B220 Coating area B230 Drying section B240 Cooling section B250 Winding section

Claims

[Claim 1] A polarizing plate protective film characterized by containing a compound having a structure represented by the following formula 1. 【Chemistry 1】

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