Polarizing plate protective film

Abstract

Disclosed is a polarizing plate protective film containing a resin and a pigment compound, which is excellent in light resistance and has no bleeding, and which is capable of protecting a display element from outdoor light and causing no light emission loss to light emission of the display element when used in a display device, particularly an organic electroluminescent display device. The polarizing plate protective film of the present application is characterized by containing a compound having a structure represented by the following Formula 1.

Description

Technical Field

[0001] This invention relates to a polarizing protective film. More specifically, it relates to a polarizing protective film containing resin and pigment compounds, which, when used in display devices, particularly organic electroluminescent display devices, can protect display elements from outdoor light, does not cause light loss to the light emission of the display elements, has no leakage, and exhibits excellent light resistance. Background Technology

[0002] Generally, to impart light-blocking properties across a wide wavelength range, including the ultraviolet region and short-wavelength visible light, to optical films such as polarizer protective films, methods include adding ultraviolet absorbers to the substrate or depositing them as another layer on the substrate. In these cases, the ultraviolet absorber is sometimes contained at a high concentration to block short-wavelength visible light, or at a high concentration accompanying the thinning of the film. However, this high concentration sometimes results in undesirable coloring, whitening, or precipitation (exudation) on the long-wavelength side. To solve these problems, a material is needed that can absorb (block) short-wavelength visible light even at low concentrations.

[0003] On the other hand, in order to prevent light loss from the light emitted by the display element used in an organic electroluminescence (EL) display device, it is necessary to ensure the transmittance of the light-emitting region (relative to the long wavelength side of 430nm) of the display element. This requires the use of materials that can suppress light absorption in this region and ensure sufficient transmittance, as well as techniques that suppress the degradation of the display element caused by outdoor light.

[0004] For example, Patent Document 1 discloses a technique in which a resin contains a light-selective absorbing compound (such as a compound containing an anthocyanin structure) that has light absorption properties on the short wavelength side of visible light in order to adjust the light absorption properties in a specific wavelength region, but there is no record of the lightfastness of the light-selective absorbing compound.

[0005] Patent document 2 discloses a highly transparent optical film containing at least one light-absorbing material selected from resin, ultraviolet absorber, and visible light absorbing pigment. The film exhibits a transmittance of less than 10% for light wavelengths of 380–410 nm and a transmittance of more than 80% for light wavelengths of 440 nm. It shows no exudation during film formation and possesses excellent ultraviolet cutoff and sharp wavelength cutoff in the short wavelength region of visible light. However, this optical film containing the light-absorbing material also lacks information regarding the lightfastness of the ultraviolet absorber and visible light absorbing pigment.

[0006] Furthermore, Patent Document 3 discloses an optical film that, by containing a specific resin (a polymer with an alicyclic structure) and an ultraviolet absorber, and a pigment compound whose transmittance can be controlled at specific wavelengths, can improve the color tone when viewing an image display device from the front while protecting the device from ultraviolet radiation. However, there is no record of the exudation durability of this optical film, and with the further thinning of the film, there is an urgent need to improve its durability.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2019-8293

[0010] Patent Document 2: Japanese Patent Application Publication No. 2017-187619

[0011] Patent Document 3: International Publication No. 2020 / 158468 Summary of the Invention

[0012] The present invention was made in view of the above-mentioned problems and circumstances, and its solution is to provide a polarizing protective film containing resin and pigment compound, which is a polarizing protective film that can protect the display element from outdoor light when used in display devices, especially organic electroluminescent display devices, and does not cause light loss to the light emission of the display element, has no leakage, and has excellent light resistance.

[0013] In order to solve the above-mentioned problems, the inventors discovered during the research on the causes of the above problems that by making the polarizing protective film contain a compound having a specific structure as shown below, a polarizing protective film containing resin and pigment compounds can be obtained, which can protect the display element from outdoor light, does not cause light loss to the light emission of the display element, does not bleed out, and has excellent light resistance.

[0014] That is, the above-mentioned problems of the present invention are solved by the following means.

[0015] 1. A polarizing protective film, characterized in that it contains a compound having a structure represented by Formula 1 below.

[0016] Mode]

[0017]

[0018] According to the above-described manner of the present invention, a polarizing protective film containing resin and pigment compounds can be provided, which is a polarizing protective film that can protect the display element from outdoor light when used in a display device, especially an organic electroluminescent display device, and does not cause light loss to the light emission of the display element, has no leakage, and has excellent light resistance.

[0019] The mechanism or mechanism of action of the effects of this invention is not yet clear, but it is speculated as follows.

[0020] Compounds having the structure represented by Formula 1 above exhibit enhanced hydrophobicity by imparting specific substituents to the benzotriazole skeleton. This enhanced hydrophobicity strengthens interactions with resins and other additives, thereby suppressing photodegradation and improving lightfastness (also known as "photofastness"). Furthermore, from the viewpoint of the sp value (also known as "solubility parameter") of the resin and the compound, good compatibility is observed, and even when added in amounts required to form the desired absorption spectrum, no exudation or whitening occurs, resulting in improved durability. Attached Figure Description

[0021] Figure 1 This is a cross-sectional view showing an example of the configuration of a polarizer 10A using the polarizer protective film of the present invention.

[0022] Figure 2 This is a cross-sectional view showing an example of the configuration of a polarizer 10B as another aspect of the present invention.

[0023] Figure 3 This is a cross-sectional view showing an example of the configuration of an organic EL display device 20 using the polarizing protective film of the present invention.

[0024] Figure 4 This is a schematic diagram illustrating a method for manufacturing a thin-film polarizer protective film according to an embodiment of the present invention.

[0025] Figure 5 This is a top view schematically showing the simplified configuration of an apparatus for manufacturing an obliquely stretched membrane.

[0026] Figure 6 It is shown schematically. Figure 5 A top view of an example of the guide rail pattern of the stretching section in the apparatus for manufacturing obliquely stretched films. Detailed Implementation

[0027] The polarizer protective film of the present invention is characterized by containing a compound having the structure represented by Formula 1 above. This feature is the same as or corresponding to the technical features in the following embodiments.

[0028] The present invention, its constituent elements, and the methods and schemes for implementing the present invention will be described in detail below. It should be noted that in this application, "~" is used to encompass the numerical values ​​described before and after it as lower and upper limits.

[0029] Summary of the Polarizing Protective Film of the Invention

[0030] The polarizer protective film of the present invention is characterized in that it contains a compound having a structure represented by the following Formula 1.

[0031] Mode]

[0032]

[0033] The structure of the polarizer protective film of the present invention will be described in detail below. It should be noted that compounds having the structure represented by Formula 1 above are referred to as "pigment compounds" in the present invention.

[0034] [1] The structure of polarizers

[0035] Figure 1 This is a cross-sectional view showing a preferred configuration example of the polarizer 10A of the present invention, having the polarizer protective film 1, polarizer layer 2, and phase retardation film 3 sequentially from the viewing side. When the polarizer protective film 1, polarizer layer 2, and phase retardation film 3 are stacked, they are preferably bonded by an adhesive layer or bonding agent layer (not shown). The phase retardation film 3 is referred to as a polarizer protective film for adjusting phase difference, depending on the intended use of the polarizer.

[0036] The polarizer used in this invention preferably has various functional layers in addition to the polarizer protective film 1, polarizer layer 2 and phase difference film 3 mentioned above. Figure 2 From the viewpoint of improving the scratch resistance of the outermost surface when the polarizer is mounted on the display device, it is preferable to configure the hard coating 4 as a functional layer as the upper layer of the polarizer protective film 1. In addition, it is also preferable to adopt a configuration in which the polarizer 10B has an adhesive layer 5 with adhesive function to adhere to the display device as the lower layer of the phase retardation film.

[0037] When describing the polarizer used in this invention, for example using polarizer 10A, from the viewpoint of the desired effect exhibited by the polarizer protective film 1 of this invention, such as... Figure 3 The preferred arrangement is that, as shown in the cross-sectional view of the organic EL display device 20, the polarizer 10A is disposed adjacent to the phase difference film 3 and bonded to the viewing side of the organic EL element 11.

[0038] [2] Pigment compounds

[0039] The pigment compound of the present invention (hereinafter also referred to as "compound (D)") is a compound having the structure represented by Formula 1 above.

[0040] This pigment compound is a compound whose maximum absorption wavelength exists in the wavelength region of 365–430 nm within the absorption spectrum of the 300–460 nm wavelength region.

[0041] (Determination of maximum absorption wavelength)

[0042] The maximum absorption wavelength of the above-mentioned compounds was determined, for example, by measuring the absorption spectrum of the pigment compounds and ultraviolet absorbers in chloroform using a UV-2450 ultraviolet-visible spectrophotometer manufactured by Shimadzu Corporation.

[0043] It should be noted that the "maximum absorption wavelength" in this invention refers to the wavelength (nm) at which the absorption spectrum of the above-mentioned compound exhibits the maximum and extremely high absorbance (absorption intensity) when the absorption spectrum of the compound is measured.

[0044] The pigment compound protects the display element from outdoor light and inhibits degradation by having its maximum absorption wavelength located in the aforementioned wavelength range, and does not cause light emission loss to the display element. Preferably, the pigment compound has the aforementioned light absorption properties, but does not have fluorescence and phosphorescence properties (photoluminescence) that suppress the display performance of organic EL elements.

[0045] This pigment compound is a substance contained in polarizing protective films. It is useful from the viewpoint of maintaining the dispersibility and transparency of resin components such as the base polymer that form the film of the polarizing protective film. That is, the hydrophobicity of the compound is improved by substituting specific substituents into the benzotriazole skeleton. This hydrophobicity strengthens its interaction with the resin and other additives, thereby suppressing the photodegradation of the compound and improving lightfastness. From the viewpoint of the sp value of the resin and the compound, it has good compatibility. Even when the amount required to form the desired absorption spectrum is added, there is no exudation or whitening, thus improving durability.

[0046] <Synthesis example>

[0047] Synthesis of pigment compound (compound 1)

[0048]

[0049] A spherical condenser, thermometer, and stirrer were installed on a 300 mL four-necked flask. 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. The mixture was refluxed at 110–115 °C for 4 hours for dehydration. The mixture was washed twice with 100 mL of warm water, and 0.2 g of activated carbon was added. After decolorization by reflux stirring, the mixture was filtered while hot. The filtrate was cooled to 5 °C, and the precipitated crystals were filtered, washed with toluene, and dried at 60 °C to obtain 5.2 g (91% yield) of compound 1.

[0050] The content of the pigment compound of the present invention is preferably in the range of 0.01 to 10 parts by mass relative to 100% of the resin component, which is a film-forming component in the polarizing protective film, and more preferably in the range of 0.02 to 8 parts by mass.

[0051] By keeping the content of the pigment compound within the above-mentioned range, when the polarizer equipped with the polarizer protective film of the present invention is used in an organic EL display device, it can fully absorb light from the area that does not affect the light emission of the organic EL element, thereby suppressing the degradation of the organic EL element.

[0052] [3] Resin

[0053] The resin used in this invention is preferably a thermoplastic resin material, and there is no limitation as long as the resin can be used as a film after film formation. For example, as a thermoplastic resin used for polarizing protective film, cellulose ester resins such as triacetyl cellulose (TAC), cellulose acetate propionate (CAP), and cellulose diacetate (DAC), cyclic olefin resins such as cyclic olefin polymers (hereinafter also referred to as COP, cyclic olefin resins), polypropylene resins such as polypropylene (PP), acrylic resins such as polymethyl methacrylate (PMMA), and polyester resins such as polyethylene terephthalate (PET) can be used.

[0054] Among them, highly hydrophobic resins have high affinity for the pigment compounds of the present invention, enabling control over the waveform of light absorption wavelengths, exhibiting excellent ultraviolet cutoff and sharp wavelength cutoff in the short wavelength region of visible light, and improving the effect of reducing light emission loss in display devices. From this viewpoint, considering the polarity, hydrophilicity, and water content of the resin, cyclic olefin resins, acrylic resins, and cellulose ester resins can be preferred in that order.

[0055] [3.1] Cycloolefin resins

[0056] The cyclic olefin resin contained in the polarizer protective film of the present invention is preferably a polymer of cyclic olefin monomers or a copolymer of cyclic olefin monomers and other comonomers.

[0057] As a cyclic olefin monomer, a cyclic olefin monomer having a norbornene skeleton is preferred, and a cyclic olefin monomer having a structure represented by the following general formula (A-1) or (A-2) is more preferred.

[0058]

[0059] In general formula (A-1), R 1 ~R 4 Each can independently represent a hydrogen atom, a hydrocarbon group with 1 to 30 carbon atoms, or a polar group. p represents an integer from 0 to 2. Where R... 1 ~R4 Not all of them simultaneously represent hydrogen atoms, R 1 and R 2 R does not simultaneously represent hydrogen atoms 3 and R 4 They do not both represent hydrogen atoms.

[0060] As R in general formula (A-1) 1 ~R 4 The hydrocarbon group representing 1 to 30 carbon atoms is preferably a hydrocarbon group with 1 to 10 carbon atoms, and more preferably a hydrocarbon group with 1 to 5 carbon atoms. The hydrocarbon group with 1 to 30 carbon atoms may further have a linking group containing a halogen atom, an oxygen atom, a nitrogen atom, a sulfur atom, or a silicon atom. Examples of such linking groups include divalent polar groups such as carbonyl, imino, ether, silyl ether, and thioether. Examples of hydrocarbon groups with 1 to 30 carbon atoms include methyl, ethyl, propyl, and butyl.

[0061] In general formula (A-1), R 1 ~R 4 Examples of polar groups include carboxyl, hydroxyl, alkoxy, alkoxycarbonyl, aryloxycarbonyl, amino, amide, and cyano. Among these, carboxyl, hydroxyl, alkoxycarbonyl, and aryloxycarbonyl are preferred, and from the viewpoint of ensuring solubility during solution film formation, alkoxycarbonyl and aryloxycarbonyl are preferred.

[0062] From the perspective of improving the heat resistance of the polarizer protective film, p in the general formula (A-1) is preferably 1 or 2. This is because when p is 1 or 2, the polymer volume increases, and the glass transition temperature is more easily increased.

[0063]

[0064] 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 This indicates a carboxyl, hydroxyl, alkoxycarbonyl, aryloxycarbonyl, amino, amide, cyano, or halogen atom (fluorine, chlorine, bromine, or iodine). p represents an integer from 0 to 2.

[0065] R in general formula (A-2) 5 Preferably, the hydrocarbon group represents 1 to 5 carbon atoms, and more preferably, the hydrocarbon group represents 1 to 3 carbon atoms.

[0066] R in general formula (A-2) 6 The preferred groups are carboxyl, hydroxyl, alkoxycarbonyl, and aryloxycarbonyl. From the viewpoint of ensuring solubility during solution film formation, alkoxycarbonyl and aryloxycarbonyl are more preferred.

[0067] From the perspective of improving the heat resistance of the polarizer protective film, p in the general formula (A-2) preferably represents 1 or 2. This is because when p is 1 or 2, the volume of the polymer increases, and the glass transition temperature is more easily increased.

[0068] From the perspective of improving solubility in organic solvents, cyclic olefin monomers having the structure represented by general formula (A-2) are preferred. Generally, organic compounds reduce crystallinity by breaking symmetry, thus increasing their solubility in organic solvents. R in general formula (A-2) 5 and R 6 The symmetry of the molecule is low because it is substituted only on one side of the ring-forming carbon atom relative to the symmetry axis of the molecule. That is, the cycloolefin monomer with the structure represented by the general formula (A-2) has high solubility, making it suitable for manufacturing polarizing protective films by solution casting.

[0069] The proportion of cyclic olefin monomers having the structure represented by general formula (A-2) in the polymer of cyclic olefin monomers relative to the total of all cyclic olefin monomers constituting the cyclic olefin resin can be, for example, 70 mol% or more, preferably 80 mol% or more, and more preferably 100 mol%. If a certain amount or more of cyclic olefin monomers having the structure represented by general formula (A-2) is contained, the orientation of the resin is improved, and therefore the phase difference (retardation) value tends to increase.

[0070] Hereinafter, specific examples of cyclic olefin monomers having the structure represented by general formula (A-1) are shown in structural formulas 1 to 14, and specific examples of cyclic olefin monomers having the structure represented by general formula (A-2) are shown in structural formulas 15 to 34.

[0071]

[0072] Examples of comonomers that can copolymerize with cyclic olefin monomers include comonomers that can undergo ring-opening copolymerization with cyclic olefin monomers and comonomers that can undergo addition copolymerization with cyclic olefin monomers.

[0073] Examples of ring-opening copolymerizable comonomers include cycloolefins such as cyclobutene, cyclopentene, cycloheptene, cyclooctene, and dicyclopentadiene.

[0074] Examples of addition copolymerizable comonomers include compounds containing unsaturated double bonds, vinyl cyclic hydrocarbon monomers, and (meth)acrylates. Examples of compounds containing unsaturated double bonds include olefinic compounds with 2 to 12 carbon atoms (preferably 2 to 8), 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 with 1 to 20 carbon atoms, such as methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and cyclohexyl (meth)acrylate.

[0075] The proportion of cyclic olefin monomers in the copolymer of cyclic olefin monomers and comonomers relative to the total of all monomers constituting the copolymer can be, for example, 20 to 80 mol%, preferably 30 to 70 mol%.

[0076] As previously mentioned, cyclic olefin resins are polymers obtained by polymerizing or copolymerizing cyclic olefin monomers having a norbornene backbone, preferably cyclic olefin monomers having a structure represented by general formula (A-1) or (A-2), and examples include the following polymers.

[0077] (1) Ring-opening polymers of cyclic olefin monomers

[0078] (2) Ring-opening copolymers of cyclic olefin monomers and comonomers that can undergo ring-opening copolymerization with them

[0079] (3) The hydride of the ring-opening (co)polymer of (1) or (2) above

[0080] (4) Hydrogenated (copolymer) formed by cyclizing the ring-opening (co)polymer of (1) or (2) above via Friedel-Crafts reaction.

[0081] (5) Saturated copolymers of cyclic olefin monomers and compounds containing unsaturated double bonds

[0082] (6) Addition copolymers of cyclic olefin monomers and vinyl cyclic hydrocarbon monomers and their hydrides

[0083] (7) Alternating copolymers of cyclic olefin monomers and (meth)acrylates

[0084] The polymers described in (1) to (7) above can all be obtained by known methods, such as those described in Japanese Patent Application Publication No. 2008-107534 and Japanese Patent Application Publication No. 2005-227606. For example, the catalyst and solvent used in the ring-opening copolymerization in (2) above can be those described in paragraphs 0019 to 0024 of Japanese Patent Application Publication No. 2008-107534. The catalyst used in the hydrogenation in (3) and (6) above above can be those described in paragraphs 0025 to 0028 of Japanese Patent Application Publication No. 2008-107534. The acidic compound used in the Friedel-Crafts reaction in (4) above above can be that described in paragraph 0029 of Japanese Patent Application Publication No. 2008-107534. The catalyst used in the addition polymerization of (5) to (7) above can be, for example, the catalyst described in paragraphs 0058 to 0063 of Japanese Patent Application Publication No. 2005-227606. The alternating copolymerization reaction of (7) above can be carried out, for example, using the method described in paragraphs 0071 and 0072 of Japanese Patent Application Publication No. 2005-227606.

[0085] Among these, polymers of (1) to (3) and (5) are preferred, and polymers of (3) and (5) are more preferred. That is, in terms of increasing the glass transition temperature and light transmittance of the obtained cyclic olefin resin, the cyclic olefin 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), more preferably it contains only the structural unit represented by general formula (B-2), or it contains both the structural units represented by general formula (B-1) and the structural units represented by general formula (B-2). The structural unit represented by general formula (B-1) is a structural unit derived from the cyclic olefin 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 cyclic olefin monomer represented by the aforementioned general formula (A-2).

[0086]

[0087] In general formula (B-1), X represents -CH=CH- or -CH2CH2-. 1 ~R 4 And p are respectively related to R in general formula (A-1) 1 ~R 4 It has the same meaning as p.

[0088]

[0089] In general formula (B-2), X represents -CH=CH- or -CH2CH2-. 5 ~R 6And p are respectively related to R in general formula (A-2) 5 ~R 6 It has the same meaning as p.

[0090] The cyclic olefin resins used in this invention can be commercially available. Examples of commercially available cyclic olefin resins include Arton G (e.g., G7810, etc.), Arton F, Arton R (e.g., R4500, R4900, and R5000, etc.) and Arton RX manufactured by JSR Corporation.

[0091] The intrinsic viscosity [η]inh of cycloolefin resins is preferably 0.2–5 cm⁻¹ when measured at 30°C. 3 The range of / g is more preferably 0.3 to 3 cm. 3 The range of / g is further preferably 0.4–1.5 cm. 3 The range of / g.

[0092] The number-average molecular weight (Mn) of the cyclic olefin 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 cyclic olefin 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 cyclic olefin resin can be determined by gel permeation chromatography (GPC) using polystyrene conversion.

[0093] <Gel Permeation Chromatography>

[0094] Solvent: dichloromethane

[0095] Columns: Shodex K806, K805, K803G (manufactured by Showa Denko Co., Ltd., for use with 3 columns)

[0096] Column temperature: 25℃

[0097] Sample concentration: 0.1% by mass

[0098] Detector: RI Model 504 (manufactured by GL Sciences)

[0099] Pump: L6000 (manufactured by Hitachi, Ltd.)

[0100] Flow rate: 1.0 mL / min

[0101] Standard curve: A standard curve based on 13 samples of standard polystyrene (STK standard polystyrene manufactured by Tosoh Corporation) with Mw values ​​ranging from 500 to 2,800,000 was used. The 13 samples were preferably used at nearly equal intervals.

[0102] If the intrinsic viscosity [η]inh, number-average molecular weight, and weight-average molecular weight are within the above ranges, the cyclic olefin resin exhibits good heat resistance, water resistance, reagent resistance, mechanical properties, and processability as a film.

[0103] The glass transition temperature (Tg) of cycloolefin resins is typically 110°C or higher, preferably in the range of 110–350°C, more preferably in the range of 120–250°C, and even more preferably in the range of 120–220°C. If the Tg is 110°C or higher, deformation under high-temperature conditions is easily suppressed. On the other hand, if the Tg is 350°C or lower, molding and processing become easier, and resin degradation caused by heat during molding and processing is also easily suppressed.

[0104] The content of cycloolefin resin relative to the membrane is preferably 70% by mass or more, and more preferably 80% by mass or more.

[0105] [3.2] Acrylic resins

[0106] The acrylic resins used in this invention are polymers of acrylates or methacrylates, and also include copolymers with other monomers.

[0107] Therefore, the acrylic resins used in this invention also include methacrylic resins. There are no particular limitations on the resin, but acrylic resins composed of methyl methacrylate units in the range of 50 to 99% by mass and other monomer units that can be copolymerized therewith in the range of 1 to 50% by mass are preferred.

[0108] Other units constituting acrylic resins formed by copolymerization include alkyl methacrylates with 2 to 18 carbon atoms, alkyl acrylates with 1 to 18 carbon atoms, isobornyl methacrylate, 2-hydroxyethyl acrylate and other hydroxyalkyl acrylates, acrylic acid, methacrylic acid and other α,β-unsaturated acids, acrylamide, N-hydroxyphenylmethylacrylamide and other acrylamides, N-vinylpyrrolidone, maleic acid, fumaric acid, itaconic acid and other dicarboxylic acids containing unsaturated groups, styrene, α-methylstyrene and other aromatic vinyl compounds, acrylonitrile, methacrylonitrile and other α,β-unsaturated nitriles, maleic anhydride, maleimide, N-substituted maleimide, glutarimide, glutaric anhydride, etc.

[0109] As monomers capable of copolymerization forming units other than glutarimide and glutaric anhydride from the above-mentioned units, monomers corresponding to the above-mentioned units can be cited. Specifically, examples include alkyl methacrylates with 2 to 18 carbon atoms in the alkyl group, alkyl acrylates with 1 to 18 carbon atoms in the alkyl group, isobornyl methacrylate, 2-hydroxyethyl acrylate and other hydroxyalkyl acrylates, acrylic acid, methacrylic acid and other α,β-unsaturated acids, acrylamide, N-hydroxyphenylmethylacrylamide and other acrylamides, N-vinylpyrrolidone, maleic acid, fumaric acid, itaconic acid and other dicarboxylic acids containing unsaturated groups, styrene, α-methylstyrene and other aromatic vinyl compounds, acrylonitrile, methacrylonitrile and other α,β-unsaturated nitriles, maleic anhydride, maleimide, N-substituted maleimide and other monomers.

[0110] Alternatively, the glutarimide unit can be formed, for example, by reacting a primary amine (imidizing agent) with an intermediate polymer having a (meth)acrylate unit (see Japanese Patent Application Publication No. 2011-26563).

[0111] Glutaric anhydride units can be formed, for example, by heating an intermediate polymer having (meth)acrylate units (see Japanese Patent No. 4961164).

[0112] From the viewpoint of mechanical strength, the acrylic resin used in this invention preferably contains isobornyl methacrylate, acrylmorpholine, N-hydroxyphenylmethacrylamide, N-vinylpyrrolidone, styrene, hydroxyethyl methacrylate, maleic anhydride, maleimide, N-substituted maleimide, glutaric anhydride, or glutarimide in the above-mentioned constituent units.

[0113] From the viewpoints of controlling dimensional changes relative to changes in ambient temperature and humidity, peelability from the metal support during membrane production, drying properties of organic solvents, heat resistance, and improved mechanical strength, the weight-average molecular weight (Mw) of the acrylic resin used in this invention is preferably 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.

[0114] If the value is above 50,000, the heat resistance and mechanical strength are excellent; if the value is below 1 million, the peelability from the metal support and the drying properties of the organic solvent are excellent.

[0115] There are no particular limitations on the method for manufacturing the acrylic resin used in this invention; any known method such as suspension polymerization, emulsion polymerization, bulk polymerization, or solution polymerization can be used. Here, common peroxide-based and azo-based polymerization initiators can be used as polymerization initiators, and redox-based initiators are also possible. For polymerization temperature, suspension or emulsion polymerization can be carried out in the range of 30–100°C, while bulk or solution polymerization can be carried out in the range of 80–160°C. To control the reduced viscosity of the resulting copolymer, alkyl thiols or the like can be used as chain transfer agents to carry out the polymerization.

[0116] From the viewpoint of maintaining the mechanical strength of the film, the glass transition temperature Tg of the acrylic resin is preferably in the range of 80 to 120°C.

[0117] Commercially available acrylic resins can also be used as the acrylic resins used in this invention. Examples include Delpet 60N, 80N, 980N, SR8200 (all manufactured by Asahi Kasei Chemicals Co., Ltd.), 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, and IPX012 (all manufactured by Denki Kagaku Kogyo Co., Ltd.). Two or more acrylic resins may also be used in combination.

[0118] The acrylic resin used in this invention preferably contains additives. As an example of an additive, it preferably contains acrylic particles (rubber elastomer particles) as described in International Publication No. 2010 / 001668 to improve the mechanical strength of the film and adjust the dimensional change rate. Examples of commercially available multilayer acrylic granular composites include, for example, "METABLEN W-341" manufactured by Mitsubishi Rayon Co., Ltd., "Kane Ace" manufactured by Kaneka Co., Ltd., "PARALOID" manufactured by Kureha Co., Ltd., "Acryloid" manufactured by Rohm and Haas Co., Ltd., "Stafiloid" manufactured by Aica Co., Ltd., Chemisnow MR-2G, MS-300X (all of which are manufactured by Soken Chemical Co., Ltd.), and "PARAPET SA" manufactured by Kuraray Co., Ltd. These can be used alone or in combination with two or more of them.

[0119] 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 value, the film can be easily stretched under heating; if the particle size is below a certain value, the transparency of the obtained film is not easily damaged.

[0120] From the viewpoint of flexibility, the flexural modulus (JIS K7171) of the polarizing protective film of the present invention is preferably 1.5 GPa or less. More preferably, it 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 elastomer particles in the film; for example, the higher the content of rubber elastomer particles, the lower the flexural modulus generally is. Furthermore, compared to using a homopolymer of alkyl methacrylate, using a copolymer of alkyl methacrylate and alkyl acrylate as the acrylic resin generally results in a lower flexural modulus.

[0121] [3.3] Cellulose ester resins

[0122] Examples of cellulose ester resins used in this invention include triacetyl cellulose (TAC), cellulose acetate propionate, cellulose diacetate, and cellulose acetate butyrate. Alternatively, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polycarbonate resins, polyolefin resins such as polyethylene and polypropylene, norbornene resins, fluoropolymers, and cycloolefin resins may be used in combination with the cellulose ester resin.

[0123] The cellulose ester used in the polarizer protective film of the present invention is preferably a carboxylic acid ester with about 2 to 22 carbon atoms, or an ester of an aromatic carboxylic acid, and preferably a lower fatty acid ester of cellulose. Here, "lower fatty acids" in lower fatty acid esters of cellulose refers to fatty acids with 6 or fewer carbon atoms.

[0124] Furthermore, the acyl group bonded to the hydroxyl group of the glucose unit constituting the cellulose ester can be a straight-chain hydrocarbon group, a branched hydrocarbon group, or a cyclic hydrocarbon group, and may also have other substituents. When the degree of substitution of the 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.

[0125] In this invention, cellulose esters may also use acyl groups derived from mixed acids. Acyl groups with 2 or 3 carbon atoms, or acyl groups with 2 or 4 carbon atoms, are preferred. Specific examples of such cellulose esters include mixed fatty acid esters of cellulose bonded with propionate or butyrate groups, in addition to acetyl groups such as cellulose acetate propionate, cellulose acetate butyrate, or cellulose acetate propionate butyrate. It should be noted that the butyryl group forming the butyrate ester can be linear or branched. Cellulose esters are preferably cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, or cellulose acetate phthalate.

[0126] The delay value of the aforementioned protective film can be appropriately controlled by the type of acyl group contained in the cellulose ester and the degree of substitution of the acyl group on the pyranose ring of the cellulose resin backbone.

[0127] The substituents bonded to the hydroxyl groups of the glucose units of the cellulose ester used in the protective film preferably satisfy both formula (a) and formula (b) below.

[0128] Equation (a): 2.0 ≤ X + Y ≤ 3.0

[0129] Equation (b): 0 ≤ Y ≤ 2.0

[0130] In formula (a) above, X represents the degree of substitution of the acetyl group, and in formulas (a) and (b), Y represents the degree of substitution of the propionyl or butyryl group. By satisfying the above two formulas, a polarizing protective film exhibiting excellent optical properties can be manufactured. Among the above cellulose esters, triacetylcellulose and cellulose acetate propionate are preferred. For cellulose acetate propionate, the degree of substitution X of the acetyl group is preferably 1.0 ≤ X ≤ 2.5 and 0.1 ≤ Y ≤ 1.5, and 2.0 ≤ X + Y ≤ 3.0.

[0131] The degree of substitution of the acyl group can be determined according to ASTM-D817-96. If the acyl group substitution is too low, there will be too much unreacted portion relative to the hydroxyl groups of the pyranose ring that constitute the backbone of the cellulose resin, resulting in a large amount of residual hydroxyl groups. Therefore, the retardation value of the polarizer protective film will vary depending on humidity, which is undesirable, and its ability to protect the polarizer layer as a polarizer protective film is reduced, which is also undesirable.

[0132] The number-average molecular weight of the aforementioned cellulose ester is preferably 60,000 to 300,000, more preferably 70,000 to 200,000. Using a cellulose ester with such a number-average molecular weight improves the mechanical strength of the polarizer protective film. The number-average molecular weight of this cellulose ester is a value determined using high-performance liquid chromatography under the following conditions.

[0133] Solvent: Acetone

[0134] Pillar: MPW x 1 (Made by Tosoh Corporation)

[0135] Sample concentration: 0.2% (mass / volume)

[0136] Flow rate: 1.0 mL / min

[0137] Injection volume: 300 μL

[0138] Standard sample: Standard polystyrene

[0139] Temperature: 23℃

[0140] The above-mentioned cellulose esters can be prepared using conventional methods.

[0141] For example, there are no particular limitations on the cellulose used as a raw material for cellulose esters; examples include cotton linters, wood pulp, and kenaf. Furthermore, cellulose esters obtained from these materials can be mixed and used in any proportion.

[0142] When acetic anhydride, propionic anhydride, butyric anhydride, or other acid anhydrides are used as acylation agents for the above-mentioned cellulose raw materials, the reaction is carried out by organic acids such as acetic acid or organic solvents such as dichloromethane and protic catalysts such as sulfuric acid. When acyl chlorides (CH3COCl, C2H5COCl, C3H7COCl) are used as acylation 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 Application Publication No. 10-45804.

[0143] [4] Other additives

[0144] The polarizing protective film of the present invention may further contain antioxidants, plasticizers, microparticles, antistatic agents, release agents, tackifiers and other additives.

[0145] From the viewpoint of further improving the effectiveness of the present invention, antioxidants and microparticles are preferred.

[0146] Antioxidants

[0147] The polarizer protective film of the present invention preferably contains an antioxidant. Antioxidants, also known as deterioration inhibitors, for example, have the function of delaying or preventing film decomposition due to residual solvents in the film, such as halogens or phosphoric acid (a phosphoric acid plasticizer).

[0148] In this invention, the light absorption waveform of the pigment compound becomes sharper by using the pigment compound and antioxidant of this invention together. As the antioxidant, hindered phenolic compounds are particularly preferred, as they have a high affinity for the pigment compound of this invention and can easily make the light absorption waveform sharper through their interaction, suppressing light absorption on the long wavelength side and thus having the effect of suppressing luminescence loss.

[0149] Examples of hindered phenolic antioxidants include, for instance, 2,6-di-tert-butyl-p-cresol, pentaerythritol tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], triethylene glycol bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and 2,4-bis-(n-octylthio)-6-(4-hydroxy-3,5-di-tert-butylaniline)-1, 3,5-triazine, 2,2-thio-diethylidene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxy-hydrogenated cinnamamide), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tris-(3,5-di-tert-butyl-4-hydroxybenzyl)-isocyanurate, etc.

[0150] Particularly preferred are 2,6-di-tert-butyl-p-cresol, pentaerythritol tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and triethylene glycol bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate]. Alternatively, hydrazine-based metal passivators such as N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine and phosphorus-based processing stabilizers such as tris(2,4-di-tert-butylphenyl)phosphite may also be used in combination.

[0151] As preferred hindered phenolic antioxidants, commercially available products can be used, such as BASF Japan's Irganox 1076 and Irganox 1010.

[0152]

[0153] The amount of these compounds added is in the range of 5% by mass or less, preferably 2% by mass or less, and more preferably 0.5% to 1% by mass relative to 100% by mass of the resin.

[0154] <particle>

[0155] The polarizer protective film of the present invention preferably contains microparticles.

[0156] Examples of inorganic compounds used in this invention include silica, titanium dioxide, alumina, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate. Alternatively, particles of organic compounds may be preferred. Examples of organic compounds include pulverized and graded products of organic polymers such as polytetrafluoroethylene, cellulose acetate, polystyrene, polymethyl methacrylate, polypropyl methacrylate, polymethyl acrylate, polyethylene carbonate, styrene-based acrylic resins, silicone resins, polycarbonate resins, benzoguanamine resins, melamine resins, polyolefin powders, polyester resins, polyamide resins, polyimide resins, or polyvinyl fluoride resins, and starch. Alternatively, polymers synthesized by suspension polymerization, polymers formed into spherical shapes by spray drying or dispersion, or inorganic compounds may be used.

[0157] The average particle size of the primary particles is preferably in the range of 5 to 400 nm, and more preferably in the range of 10 to 300 nm.

[0158] These can be mainly contained in the form of secondary aggregates with a particle size in the range of 0.05 to 0.3 μm, or preferably in the form of primary particles without agglomeration if the particles have an average particle size in the range of 100 to 400 nm.

[0159] The microparticles preferably contain silicon, and more particularly silicon dioxide, in order to reduce the turbidity of the membrane. For example, commercially available products using the silicon dioxide microparticles under the trade names AEROSIL R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, and TT600 (all manufactured by AEROSIL Co., Ltd. of Japan) can be used.

[0160] In particular, the silicon-containing particles have a high affinity for the pigment compounds involved in this invention. By using them in combination, the light absorption waveform becomes sharper, and light absorption on the long wavelength side is suppressed, thereby suppressing the light emission loss of the display device. Among the silicon-containing particles, the aforementioned R812 or R972 are preferred. Silicon-containing particles with higher hydrophobicity have a high affinity for the pigment compounds of this invention, and the effect of reducing the aforementioned light emission loss is obtained through their interaction.

[0161] These microparticles can be used alone or in combination with two or more. The content of the microparticles is used in a range of 10% by mass or less, preferably 5% by mass or less, and more preferably 0.5% to 2% by mass or less relative to 100% by mass of the resin.

[0162] In this invention, in order to add microparticles during the manufacturing process, it is preferable to use online addition for mixing. For example, it is preferable to use an online mixer such as a static mixer (Toray Engineering) or SWJ (Toray Hi-Mixer static in-tube mixer).

[0163] <Ultraviolet absorber>

[0164] The polarizing protective film of the present invention may also contain ultraviolet absorbers as other pigment compounds as needed.

[0165] The aforementioned "ultraviolet absorber" is preferably a compound whose maximum absorption wavelength exists in the range of 300-359 nm in the absorption spectrum of the wavelength region of 300-460 nm. There is no particular limitation as long as the maximum absorption wavelength exists in the wavelength region of 300-359 nm.

[0166] Examples of UV absorbers used include triazine-based UV absorbers, benzotriazole-based UV absorbers, benzophenone-based UV absorbers, oxybenzophenone-based UV absorbers, salicylates-based UV absorbers, and cyanoacrylate-based UV absorbers. One of these absorbers can be used alone or in combination of two or more.

[0167] Among these, triazine-based UV absorbers and benzotriazole-based UV absorbers are preferred, with at least one UV absorber selected from 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 exhibit good solubility in resin components, such as the base polymer, which forms the film of the optical film containing the UV absorber. Furthermore, these UV absorbers are preferred because they have high UV absorption capacity around a wavelength of 380 nm.

[0168] As triazine-based ultraviolet absorbers having two or fewer hydroxyl groups per molecule, examples include 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 with [(C10-C16 (mainly C12-C13)alkyloxy)methyl]ethylene oxide (TINUVIN). 400 (BASF), 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-[3-(dodecyloxy)-2-hydroxypropoxy]phenol, the reaction product of 2-(2,4-dihydroxyphenyl)-4,6-bis-(2,4-dimethylphenyl)-1,3,5-triazine with (2-ethylhexyl)-glycidyl 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) 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), 6,6',6”-(1,3,5-triazine-2,4,6-triyl)tris(3-hexyloxy-2-methylphenol) (LA-F70, manufactured by ADEKA Corporation), etc.

[0169] In addition, examples of benzotriazole-based UV absorbers having one benzotriazole skeleton per 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), ester compounds of phenylpropionic acid and 3-(2H-benzotriazole-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy (C7-9 side chain and straight-chain alkyl) (TINUVIN 384-2, manufactured by BASF), and 2-(2H-benzotriazole-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (TINUVIN). 900 (BASF), the reaction product of methyl-3-(3-(2H-benzotriazol-2-yl)-5-tert-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 (BASF), 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (TINUVIN 329, BASF), the reaction product of methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate with polyethylene glycol 300 (TINUVIN 213, BASF), 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol (TINUVIN) 571 (manufactured by BASF), 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimide-methyl)-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 Shipro Chemical Co., Ltd., or KEMISORB 73, manufactured by Shipro Chemical Co., Ltd.), etc.

[0170] In addition, examples of benzophenone-based ultraviolet absorbers (benzophenone compounds) and oxybenzophenone-based ultraviolet absorbers (oxybenzophenone compounds) include, for example, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (anhydrous salt and trihydrate salt), 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 Shipro Chemical Co., Ltd.), and 2,2'-dihydroxy-4-methoxybenzophenone (KEMISORB 111, manufactured by CHEMIPRO Chemical Co., Ltd.).

[0171] In addition, examples of salicylate-based ultraviolet absorbers (salicylate compounds) include, for example, 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).

[0172] Examples of cyanoacrylate-based ultraviolet absorbers (cyanoacrylate compounds) include, for example, alkyl-2-cyanoacrylates, cycloalkyl-2-cyanoacrylates, alkoxyalkyl-2-cyanoacrylates, alkenyl-2-cyanoacrylates, and alkynyl-2-cyanoacrylates.

[0173] Ultraviolet absorbers can be used alone or in combination of two or more. The content of ultraviolet absorbers is expressed as the mass parts of the ultraviolet absorber relative to 100 parts by mass of the resin component, which is a film-forming component of the optical film.

[0174] For example, when the optical film contains an ultraviolet absorber, the content of the ultraviolet absorber relative to 100 parts by weight of the resin constituting the optical film is preferably in the range of 0.1 to 8 parts by weight, and more preferably in the range of 0.5 to 5 parts by weight.

[0175] By ensuring the content of the ultraviolet absorber is within the aforementioned range, the layer containing the ultraviolet absorber can fully exert its ultraviolet absorption function, which is therefore preferable. Furthermore, when the polarizer used in this invention is applied to an organic EL display device, by containing the aforementioned compound (D) and further containing the ultraviolet absorber, the organic EL display device can maintain its quality over a long period by utilizing its function of protecting the organic EL display element from outdoor light.

[0176] [5] Manufacturing of polarizing protective film

[0177] As a method for manufacturing the polarizer protective film of the present invention, conventional manufacturing methods such as blow molding, T-die molding, calendering, cutting, casting, emulsion molding, and hot pressing can be used. However, from the viewpoint of suppressing coloration, foreign matter defects, and optical defects such as mold lines, the film-forming method is preferably solution casting and melt casting. In particular, from the viewpoint of low temperature in the processing steps, and thus high functionality can be imparted by using various additives, solution casting is more preferred. Hereinafter, the preferred "solution casting method" in the present invention will be described.

[0178] When manufacturing a polarizing protective film using solution casting, a manufacturing method comprising the steps (1) to (3) is specifically used. Furthermore, this manufacturing method preferably includes step (4).

[0179] (1) A process for obtaining a coating comprising a film-forming component containing a thermoplastic resin, an added compound (D) and any additives, and a solvent.

[0180] (2) The process of casting the obtained coating onto the support, drying and peeling it to obtain a film.

[0181] (3) The process of stretching and drying the obtained film as needed.

[0182] (4) The process of winding the obtained polarizing protective film to obtain a roll body.

[0183] (1) process

[0184] Coatings are prepared by dissolving or dispersing film-forming components containing thermoplastic resins, added compounds (D), antioxidants, microparticles, and other additives in a solvent.

[0185] The solvents used in the coatings include organic solvents (good solvents) capable of dissolving at least thermoplastic resins. When compound (D) is present, the organic solvent preferably 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.

[0186] The solvent used in the coating may further include a solvent-poor component. Examples of solvent-poor components include straight-chain or branched aliphatic alcohols with 1 to 4 carbon atoms. If the proportion of alcohols in the coating increases, the film is more likely to gel and peel off from the metal support. Examples of straight-chain or branched aliphatic alcohols with 1 to 4 carbon atoms include methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, and tert-butanol. Among these, ethanol is preferred due to its stability, low boiling point, and good drying properties.

[0187] (2) process

[0188] The resulting coating is cast onto a support. The coating can be cast by spraying it from a casting die.

[0189] Next, the solvent in the coating cast onto the support is evaporated, and the coating is dried. The dried coating is then peeled off the support, thus obtaining a film.

[0190] The amount of residual solvent in the coating when peeled off from the support (the amount of residual solvent in the film at the time of peeling) is preferably 20% by mass or more, 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 easy to suppress excessive stretching of the film caused by peeling.

[0191] The amount of residual solvent in the coating during stripping is defined by the following formula. The same applies below.

[0192] Residual solvent content of coating (mass%) = (mass of coating before heat treatment - mass of coating after heat treatment) / mass of coating after heat treatment × 100

[0193] It should be noted that the heat treatment for determining the residual solvent amount refers to a heat treatment at 140°C for 30 minutes.

[0194] The amount of residual solvent during peeling can be adjusted according to the drying temperature and time of the coating on the support, the temperature of the support, etc.

[0195] (3) process

[0196] The resulting film is then dried. Drying can be done in one step or in multiple steps. Alternatively, drying can be performed while stretching the film as needed.

[0197] For example, the drying process of a film may include: a process for pre-drying the film (pre-drying process), a process for stretching the film (stretching process), and a process for drying the stretched film (main drying process).

[0198] (Preparatory drying process)

[0199] 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 set to Tg, it is preferably (Tg-50)~(Tg+50)℃. If the pre-drying temperature is above (Tg-50)℃, the solvent is more likely to evaporate appropriately, thus improving the conveyability (processability). If it is below (Tg+50)℃, the solvent will not evaporate excessively, thus minimizing damage to the stretchability in the subsequent stretching process. The initial drying temperature can be measured as the temperature inside the stretching machine or the atmosphere temperature, such as the hot air temperature, when drying is performed using a non-contact heating type while being conveyed by a stretching machine and rollers in (a) on the other hand.

[0200] (Stretching process)

[0201] Stretching can be performed according to the required optical properties, such as the retardation value. It is preferred to stretch in at least one direction, but stretching can be performed in two mutually orthogonal directions (e.g., biaxial stretching in the width direction (TD direction) and the transport direction (MD direction) orthogonal to it of the film).

[0202] The stretching ratio during the manufacture of the polarizing protective film is preferably 5 to 100%, more preferably 20 to 100%. When performing biaxial stretching, the stretching ratio in each direction is preferably within the above range.

[0203] The stretch ratio (%) is defined as (stretch magnitude of the film after stretching - stretch magnitude of the film before stretching) / (stretch magnitude of the film before stretching) × 100. It should be noted that, during biaxial stretching, the above stretch ratios are preferred for both the TD and MD directions.

[0204] As described above, the stretching temperature (drying temperature during stretching) is preferably above Tg (°C) when the glass transition temperature of the thermoplastic resin is set to Tg, and more preferably (Tg+10) to (Tg+50)°C. If the stretching temperature is above Tg (°C), preferably above (Tg+10)°C, the solvent is easily volatilized to a moderate degree, thus making it easy to adjust the stretching tension to an appropriate range. If it is below (Tg+50)°C, the solvent does not volatilize excessively, thus minimizing damage to the stretchability. The stretching temperature during the manufacture of the polarizing protective film can, for example, be above 115°C. As described above, the stretching temperature is preferably measured by measuring the ambient temperature, such as the temperature inside the stretching machine (a).

[0205] The amount of residual solvent in the film at the start of stretching is preferably the same as the amount of residual solvent in the film at the time of peeling, for example, preferably 20-30% by mass, more preferably 25-30% by mass.

[0206] Stretching of the film in the TD direction (width direction) can be achieved, for example, by fixing both ends of the film with clips or pins and widening the spacing between the clips or pins in the traveling direction (stretching method). Stretching of the film in the MD direction can be achieved, for example, by imparting a circumferential speed difference to multiple rollers and utilizing the roller circumferential speed difference between them (roller method).

[0207] (Main drying process)

[0208] From the viewpoint of further reducing the amount of residual solvent, it is preferable to further dry the film obtained after stretching. For example, it is preferable to further dry the film obtained after stretching while conveying it with rollers or the like.

[0209] When the glass transition temperature of the thermoplastic resin is set to Tg, the main drying temperature (the drying temperature before stretching) is preferably (Tg-50) to (Tg-30) °C, more preferably (Tg-40) to (Tg-30) °C. If the post-drying temperature is above (Tg-50) °C, the solvent can be easily evaporated and removed from the stretched film; if it is below (Tg-30) °C, deformation of the film can be highly suppressed. As described above, the main drying temperature is preferably measured by measuring the atmosphere temperature, such as (a) the hot air temperature.

[0210] (4) process

[0211] The obtained polarizing protective film is preferably in the form of a long strip. The long strip of polarizing protective film is wound into a roll to form a roll body.

[0212] There is no particular limitation on the length of the strip-shaped polarizing protective film; for example, it can be about 100 to 10,000 m. In addition, the width of the polarizing protective film is preferably more than 1 m, and more preferably 1.3 to 4 m.

[0213] The thickness of the polarizer protective film can be appropriately determined, generally considering factors such as strength, workability, and thinness, and is preferably in the range of 1 to 500 μm. More preferably, the thickness of the polarizer protective film is in the range of 5 to 50 μm, and even more preferably in the range of 10 to 45 μm.

[0214] Furthermore, the pigment compounds of the present invention exhibit improved compatibility with resins, do not cause exudation or whitening, and have improved durability. Therefore, they are also preferably used in thin-film polarizing protective films with a thickness of 1 μm or more and less than 10 μm. Thin-film polarizing films can be fabricated using thin-film polarizing protective films (hereinafter also referred to as "thin-film polarizing protective films").

[0215] <Manufacturing of Thin-Film Polarizing Protective Film>

[0216] Another embodiment of the present invention provides a method for manufacturing a thin-film polarizer protective film, comprising: 1) a step of obtaining a solution for a thin-film polarizer protective film, 2) a step of applying the obtained solution for a thin-film polarizer protective film to the surface of a support, and 3) a step of removing solvent from the applied solution for a thin-film polarizer protective film to form a thin-film polarizer protective film.

[0217] 1) Process for obtaining the solution for the protective film of the thin-film polarizer

[0218] The process for obtaining the solution for the protective film of the thin-film polarizer is the same as the process for preparing the aforementioned "coating" and can be referred to accordingly.

[0219] 2) Process of applying a protective film to a thin-film polarizer using a solution

[0220] Next, the obtained thin-film polarizer protective film is applied to the surface of the support using a solution. Specifically, the obtained thin-film polarizer protective film is coated onto the surface of the support using a solution. The laminate of the support and the thin-film polarizer protective film is also called a "laminated film".

[0221] <Support>

[0222] The support is used to support the thin-film polarizer protective film during its formation, and typically comprises a resin film. The film thickness of the support is preferably 50 μm or less. From the perspective of requiring a certain degree of strength (stiffness, rigidity) to function as a support despite being a thin film, the film thickness of the support is preferably in the range of 15–45 μm, and more preferably in the range of 20–40 μm.

[0223] Examples of resins 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 as they exhibit excellent preservation properties under high humidity conditions.

[0224] Examples of resin films include polyester resins (e.g., polyethylene terephthalate (PET), polypropylene 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.

[0225] The resin film can be a heat-treated (heat-mitigated) resin film or a stretch-treated resin film.

[0226] Heat treatment is used to reduce residual stress in the resin film (e.g., residual stress accompanied by tension). There are no particular limitations. When the glass transition temperature of the resin constituting the resin film is set as Tg, it can be carried out at (Tg+60) to (Tg+180) °C.

[0227] Stretching is used to increase the residual stress of the resin film. Stretching is preferably performed, for example, in two axes of the resin film. Stretching can be performed under any conditions, for example, at a stretching ratio of approximately 120 to 900%. Whether the resin film has been stretched can be confirmed, for example, by the presence of an in-plane slow axis (the axis along the direction of maximum refractive index). Stretching can be performed before or after the thin-film polarizer protective film is laminated, but it is preferred to perform stretching before lamination.

[0228] Polyester resin films (also known as polyester films) can be commercially available, such as polyethylene terephthalate film TN100 (manufactured by Toyobo Co., Ltd.) and MELINEX ST504 (manufactured by Teijin DuPont Film Co., Ltd.).

[0229] The support may further have a release layer disposed on the surface of the resin film. The release layer allows the support to be easily peeled off from the protective film of the thin-film polarizer during the fabrication of the polarizer.

[0230] The release layer may contain known release agents without particular limitation. Examples of release agents contained in the release layer include silicone-based and non-silicone-based release agents.

[0231] Examples of silicone-based release agents include known silicone resins. Examples of non-silicone-based release agents include: long-chain alkyl side-chain 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), polyaryl resins (e.g., condensation polymers of aromatic dicarboxylic acid components and divalent phenol components), fluoropolymers (e.g., polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), PFA (a copolymer of tetrafluoroethylene and perfluoroalkoxyethylene), FEP (a copolymer of tetrafluoroethylene and hexafluoropropylene), ETFE (a copolymer of tetrafluoroethylene and ethylene)), etc.

[0232] The thickness of the release layer is not particularly limited as long as it can exhibit the desired degree of peelability; for example, it is preferably in the range of 0.1 to 1.0 μm.

[0233] The support may contain a plasticizer as an additive. There are no particular limitations on the type of plasticizer, but it is preferably selected from polyol ester plasticizers, phthalate ester plasticizers, citric acid plasticizers, fatty acid ester plasticizers, phosphate ester plasticizers, polycarboxylic acid ester plasticizers, and polyester plasticizers, etc.

[0234] In addition, the support may also contain the aforementioned ultraviolet absorbers and microparticles.

[0235] As for the manufacturing method of the support used in this invention, conventional methods such as blow molding, T-die molding, calendering, cutting, casting, emulsion molding, and hot pressing can be used. From the viewpoint of suppressing coloration, foreign matter defects, and optical defects such as mold lines, solution casting and melt casting are preferred film-forming methods. Furthermore, if solution casting is used, the temperature in the processing steps is low, so high functionality can be imparted by using various additives.

[0236] Preferably, the support structure manufactured as described above is used to form the thin-film polarizer protective film of the present invention using the following method.

[0237] There are no particular limitations on the coating method for the solution used in the thin-film polarizer protective film. For example, known methods such as back roller coating, gravure coating, spin coating, wire rod coating, and roller coating can be used. Among these, the back roller coating method is preferred from the viewpoint of forming a thin and uniform film thickness.

[0238] 3) The process of forming the thin-film polarizer protective film

[0239] Next, the solvent is removed from the solution of the thin-film polarizer protective film applied to the support to form the thin-film polarizer protective film.

[0240] Specifically, the thin-film polarizer protective film applied to the support is dried with a solution. Drying can be carried out, for example, by air supply or heating. Among these methods, air supply is preferred for drying, as it is easier to suppress warping of the thin-film polarizer protective film.

[0241] 4) The process of winding the thin-film polarizing protective film to obtain a roll.

[0242] The obtained strip-shaped thin-film polarizer protective film is wound into a roll shape in a direction orthogonal to its width direction to form a roll body.

[0243] The length of the strip-shaped thin-film polarizer protective film is not particularly limited, and can be, for example, around 100 to 10,000 m. Furthermore, the width of the strip-shaped laminated film is preferably 1 m or more, more preferably 1.1 to 4 m. From the viewpoint of improving film uniformity, 1.3 to 2.5 m is more preferred.

[0244] [Manufacturing Equipment]

[0245] The thin-film polarizer protective film used in this invention can be manufactured, for example, by utilizing... Figure 4 The manufacturing process is carried out using the apparatus shown.

[0246] Figure 4 This is a schematic diagram of a manufacturing apparatus B200 used in the method for manufacturing a thin-film polarizing protective film according to this embodiment. The manufacturing apparatus B200 includes: a supply unit B210, a coating unit B220, a drying unit B230, a cooling unit B240, and a winding unit B250. Ba to Bd represent the conveyor rollers that convey the support body B110.

[0247] The supply unit B210 has a pull-out device (not shown) for pulling out the roll B201 of the strip support B110 that is wound into a core.

[0248] The coating section B220 is a coating apparatus, which includes a support roller B221 that holds the support body B110, a coating head B222 that coats the support body B110 held by the support roller B221 with a solution for coating a thin film polarizer protective film, and a decompression chamber B223 disposed on the upstream side of the coating head B222.

[0249] The flow rate of the thin-film polarizer protective film solution ejected from coating head B222 can be adjusted by a pump (not shown). The flow rate of the thin-film polarizer protective film solution ejected from coating head B222 is set to the amount that can stably form a coating layer of a specified thickness when continuous coating is performed under the pre-adjusted conditions of coating head B222.

[0250] The pressure-reducing chamber B223 is a mechanism used during coating to stabilize the droplets (retention of coating liquid) formed between the thin-film polarizer protective film solution from the coating head B222 and the support B110. It allows for adjustment of the pressure reduction. The pressure-reducing chamber B223 is connected to a pressure-reducing blower (not shown) to reduce internal pressure. The pressure-reducing chamber B223 is kept airtight, and the gap between it and the support roller is adjusted to be narrow, enabling the formation of stable coating liquid droplets.

[0251] The drying unit B230 is a drying apparatus for drying the coating film applied to the surface of the support B110. It includes a drying chamber B231, an inlet B232 for drying gas, and an outlet B233. The temperature and flow rate of the drying air are appropriately determined according to the type of coating film and the type of support B110. By setting the temperature, flow rate, and drying time of the drying air in the drying unit B230, the residual solvent content of the dried coating film can be adjusted. The residual solvent content of the dried coating film can be measured by comparing the unit mass of the dried coating film with the mass of the coating film after thorough drying.

[0252] (Residual solvent content)

[0253] Thin-film polarizer protective films are obtained by coating with a solution, and therefore sometimes residual solvent from that solution remains. The amount of residual solvent can be controlled by factors such as the concentration of the solvent and coating solution used, the air velocity during drying of the thin-film polarizer protective film, the drying temperature and time, the conditions of the drying chamber (external air or internal gas circulation), and the heating temperature of the support rollers during coating.

[0254] As mentioned earlier, if high-speed drying is used, the film becomes sparse, which allows for control of the surface state.

[0255] From the perspective of warpage balance of the thin-film polarizer protective film, the preferred residual solvent content of the thin-film polarizer protective film is such that when the residual solvent content of the thin-film polarizer protective film is set to S1, the following inequality 1 is satisfied.

[0256] Formula 1: 10 < S1 < 1000 (ppm)

[0257] Specifically, the residual solvent content of the thin-film polarizer protective film is more preferably less than 800 ppm, and more preferably less than 500 to 700 ppm, taking into account the warpage balance of the thin-film polarizer protective film. Furthermore, by selecting solvents that also leave residues on the support and by using appropriate coating processes, the adhesion between the support and the thin-film polarizer protective film is improved. The residual solvent content of the support is preferably in the range of 10 to 100 ppm.

[0258] The residual solvent content in the support and the thin-film polarizer protective film can be determined using headspace gas chromatography (HGC). In HGC, the sample is sealed in a container, heated, and the gas is rapidly injected into the gas chromatograph while the container is filled with volatile components. Mass spectrometry analysis is then performed, simultaneously identifying compounds and quantifying volatile components. In headspace chromatography, the total peak of volatile components can be observed using gas chromatography, and quantification of volatile substances and monomers can be achieved with high precision using analytical methods utilizing electromagnetic interactions.

[0259] The cooling section B240 cools the support B110, which has a coating (thin-film polarizer protective film) dried by the drying section B230, and adjusts it to an appropriate temperature. The cooling section B240 includes 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 according to the type of coating and the type of support B110. Alternatively, the cooling section B240 can be omitted if an appropriate cooling temperature is achieved.

[0260] The winding section B250 is a winding device (not shown) for winding a support B110 to obtain a roll B251 by winding the support B110 to which a thin-film polarizer protective film is formed.

[0261] [6] Polarizer layer

[0262] A polarizer layer is a component layer that allows light from a polarized surface in only a specific direction to pass through. Examples of polarizer layers include films formed by uniaxially stretching hydrophilic polymer films such as polyvinyl alcohol films (where dichroic substances like iodine or dichroic dyes are adsorbed onto the film), partially formaldehyde-modified polyvinyl alcohol films, or partially saponified ethylene-vinyl acetate copolymer films, as well as polyene-based oriented films such as dehydrated polyvinyl alcohol products and dehydrochlorinated polyvinyl chloride products. Among these, a polarizer layer composed of a polyvinyl alcohol film and dichroic substances such as iodine is preferred. The thickness of these polarizer layers is not particularly limited and is generally around 5–80 μm.

[0263] A polarizer layer, formed by dyeing a polyvinyl alcohol (PVA) film with iodine and then uniaxially stretching it, can be produced by dyeing PVA by immersing it in an aqueous solution of iodine and then stretching it to 3 to 7 times its original length. Alternatively, it can be immersed in an aqueous solution containing boric acid, zinc sulfate, zinc chloride, or potassium iodide, as needed. Furthermore, the PVA film can be washed with water before dyeing, as required. Besides cleaning the surface of the PVA film and removing anti-blocking agents by washing, washing also prevents uneven dyeing by causing the PVA film to swell. Stretching can be performed after dyeing with iodine, during dyeing, or after stretching followed by dyeing with iodine. Stretching can also be performed in aqueous solutions of boric acid, potassium iodide, etc., or in a water bath.

[0264] Alternatively, a thin polarizer layer with a thickness of 10 μm or less can be used in this invention. From the viewpoint of thinness, a thickness of 1 to 7 μm is preferred. Such a thin polarizer layer has excellent visibility due to its less thickness unevenness and less dimensional variation, and therefore has excellent durability, making it preferable in terms of achieving thinness as a polarizing film.

[0265] Examples of thin polarizer layers include the thin polarizing films described in Japanese Patent Application Publication No. 51-069644, Japanese Patent Application Publication No. 2000-338329, International Publication No. 2010 / 100917, International Publication No. 2010 / 100917, Japanese Patent No. 4751481, and Japanese Patent Application Publication No. 2012-073563. These thin polarizing films can be obtained by a manufacturing method comprising 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 dyeing process. With this manufacturing method, even if the PVA-based resin layer is thin, it can be stretched without defects such as breakage due to stretching by supporting it on the stretching resin substrate.

[0266] As for the aforementioned thin polarizing film, in a manufacturing method that includes a stretching process in a laminated state and a dyeing process, in terms of improving polarization performance by completing the stretching at a high magnification, it is preferable to obtain the film by a process involving stretching in a boric acid aqueous solution as described in International Publication No. 2010 / 100917, International Publication No. 2010 / 100917, or Japanese Patent No. 4751481 and Japanese Unexamined Patent Application Publication No. 2012-073563. In particular, it is preferable to obtain the film by a process involving auxiliary air stretching before stretching in a boric acid aqueous solution as described in Japanese Patent No. 4751481 and Japanese Unexamined Patent Application Publication No. 2012-073563.

[0267] [7] Phase difference film

[0268] Phase retardation films can be any type of film that has a phase retardation and can function as an optical compensation layer. When using a transparent film with a phase retardation, its phase retardation characteristics can be appropriately adjusted to the value required for optical compensation.

[0269] As a retardation film, for example, when the refractive index in the slow axis direction is set as nx, the refractive index in the fast axis direction is set as ny, and the refractive index in the thickness direction is set as nz, the following relationships are satisfied: nx = ny > nz, nx > ny > nz, nx > ny = nz, nx > nz > ny, nz = nx > ny, nz > nx > ny, nz > nx = ny, but the appropriate relationship is chosen according to various applications. It should be noted that nx = ny not only refers to the case where nx and ny are exactly the same, but also includes the case where nx and ny are substantially the same. Furthermore, ny = nz not only refers to the case where ny and nz are exactly the same, but also includes the case where ny and nz are substantially the same.

[0270] When a polarizer is used in an organic EL display device, the retardation film is preferably a quarter-wavelength plate with an in-plane retardation value of 1 / 4 wavelength (approximately 100–170 nm). It is therefore preferable to use a circular polarizer for anti-reflection in an organic EL display device by stacking a polarizer layer with the quarter-wavelength plate (retardation film).

[0271] That is, external light incident on the organic EL display device is transmitted only by the polarizer layer, allowing only the linearly polarized light component to pass through. This linearly polarized light is generally converted into elliptically polarized light by passing through the retardation film. In particular, the retardation film is a 1 / 4 wavelength plate, and when the angle between the retardation film and the polarization direction of the light is π / 4, it becomes circularly polarized light.

[0272] The circularly polarized light passes through the transparent substrate, transparent electrode, and organic thin film in the organic EL panel. Reflected by the metal electrode, it passes through the organic thin film, transparent electrode, and transparent substrate again, and then becomes linearly polarized light again through the retardation film. Furthermore, this linearly polarized light is orthogonal to the polarization direction of the polarizer layer, and therefore cannot pass through the polarizer layer. As a result, the mirror surface of the metal electrode can be completely blocked.

[0273] As the phase retardation film, a stretched film formed by stretching a film with a thermoplastic resin as the film-forming component is preferred. As the thermoplastic resin, the same thermoplastic resin described as the constituent material of the polarizer protective film described above can be used.

[0274] The phase difference film may contain microparticles, phase difference modifiers, antioxidants, plasticizers, antistatic agents, stripping agents, and other additives, within a range that does not impair the effects of this embodiment.

[0275] The retardation film can be a single-layer or multi-layer laminate. It should be noted that when the retardation film is a laminate, the thermoplastic resins used in the formation of each layer can be the same or different. Conventionally known methods can be used without particular limitation as the manufacturing method for the laminate.

[0276] In addition to the aforementioned cyclic olefin resins, cellulose ester resins, and acrylic resins, polycarbonate resins are preferably used as thermoplastic resins in the formation of the retardation film. In particular, polycarbonate resins are preferred when manufacturing the obliquely stretched film described later. When the retardation film is a laminated film, a combination of cellulose ester resin and polycarbonate resin layers is preferred, for example.

[0277] (Polycarbonate resin)

[0278] Various polycarbonate resins can be used without particular limitation as the polycarbonate resin. From the perspective of chemical properties and physical properties, aromatic polycarbonate resins are preferred, and polycarbonates with a fluorene backbone and bisphenol A-based polycarbonate resins are particularly preferred. Among these, polycarbonate resins containing bisphenol A derivatives obtained by introducing benzene rings, cyclohexane rings, and aliphatic hydrocarbon groups into bisphenol A are more preferred. Furthermore, polycarbonate resins with a structure that reduces intramolecular anisotropy, obtained by asymmetrically introducing derivatives of the aforementioned functional groups relative to the central carbon of bisphenol A, are particularly preferred.

[0279] As such polycarbonate resins, compounds in which the two methyl groups of the central carbon of bisphenol A are substituted into benzene rings are particularly preferred, as are compounds obtained by asymmetrically substituting the hydrogens at each position of the benzene ring of bisphenol A with methyl groups, phenyl groups, etc., relative to the central carbon. Specifically, these are compounds obtained by using the phosgene process or transesterification process from 4,4'-dihydroxydiphenylalkanes or their halogenated derivatives, such as 4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenylethane, and 4,4'-dihydroxydiphenylbutane. In addition, specific examples of polycarbonate resins can be given, such as those described in Japanese Patent Application Publication No. 2006-215465, Japanese Patent Application Publication No. 2006-91836, Japanese Patent Application Publication No. 2005-121813, Japanese Patent Application Publication No. 2003-167121, Japanese Patent Application Publication No. 2009-126128, Japanese Patent Application Publication No. 2012-67300, and International Publication No. 2000 / 026705.

[0280] (Fabrication of phase retardation film)

[0281] The phase retardation film can be manufactured using the same known forming methods as the polarizing protective film described above, such as melt casting, solution casting, and calendering. Melt casting and solution casting are preferred, with solution casting being particularly preferred.

[0282] The phase retardation film can be manufactured by using resin and any additives in the coating process of (1) of the solution casting method described in the polarizer protective film. Alternatively, the phase retardation film can be manufactured by further obliquely stretching the film substrate obtained in the process of (3) or (4) of the solution casting method described in the polarizer protective film.

[0283] To manufacture elongated, obliquely stretched membranes using membrane substrates, for example, using... Figure 5 and Figure 6 The diagram illustrates a simplified version of the device. Figure 5 This is a top view schematically showing the simplified configuration of the obliquely stretched film manufacturing apparatus 80. Figure 6 This is a top view schematically showing an example of the guide rail pattern of the stretching section of the manufacturing apparatus 80 for obliquely stretched film. The manufacturing apparatus 80 includes, in sequence from the upstream side of the conveying direction of the film substrate, a film extraction section 81, a conveying direction changing section 82, a guide roller 83, a stretching section 84, a guide roller 85, a conveying direction changing section 86, and a film winding section 87.

[0284] The membrane extraction section 81 extracts the membrane substrate produced as described above and supplies it to the stretching section 84. The conveying direction changing section 82 changes the conveying direction of the membrane substrate extracted from the membrane extraction section 81 to the direction towards the entrance of the stretching section 84, which serves as an oblique stretching tenter. To stabilize the trajectory of the membrane substrate during its travel, at least one guide roller 83 is provided on the upstream side of the stretching section 84. To stabilize the trajectory of the membrane after oblique stretching by the stretching section 84 during its travel, at least one guide roller 85 is provided on the downstream side of the stretching section 84. The conveying direction changing section 86 changes the conveying direction of the stretched membrane conveyed from the stretching section 84 to the direction towards the membrane winding section 87. The membrane winding section 87 winds the membrane conveyed from the stretching section 84 via the conveying direction changing section 86.

[0285] based on Figure 6 The details of the stretching section 84 are explained below. The manufacture of the obliquely stretched membrane can be achieved, for example, using... Figure 6 The tenter frame (oblique stretching machine) shown is used as the stretching section 84. This tenter frame is a device that heats a film substrate to an arbitrary stretchable temperature and performs oblique stretching. It includes: a heating zone Z, a pair of guide rails Ri and Ro (left and right), and multiple holding members Ci and Co (right and left) that transport the film along the guide rails Ri and Ro. Figure 6 (Only one set of holding parts is shown in the diagram). It should be noted that details of the heating zone Z will be described later. The guide rails Ri and Ro connect multiple guide rail sections via connecting parts. Figure 6 The white dot in the image is an example of a connecting part. The holding members Ci and Co are composed of clamps at both ends of the holding membrane in the width direction.

[0286] Figure 6 In this process, the extraction direction D1 of the membrane substrate differs from the winding direction D2 of the stretched obliquely stretched membrane, and forms an extraction angle θi with respect to the winding direction D2. The extraction angle θi can be arbitrarily set to the desired angle within a range greater than 0° and less than 90°.

[0287] Because the extraction direction D1 and the winding direction D2 are different, the guide rail pattern of the tenter frame is asymmetrical. Then, the guide rail pattern can be manually or automatically adjusted based on the orientation angle θ, stretch ratio, etc., provided for the 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 guide rail portion and guide rail connecting portion constituting guide rails Ri and Ro can be freely set, and the guide rail pattern can be arbitrarily changed. Therefore, the orientation angle of the film can be set arbitrarily.

[0288] In the stretching section 84, the membrane substrate is held at both ends by left and right gripping members Ci and Co, and is conveyed within the heating zone Z as the gripping members Ci and Co move. The left and right gripping members Ci and Co are positioned opposite each other at the inlet of the stretching section 84 (position A in the figure), in a direction approximately perpendicular to the membrane's travel direction (extraction direction D1), and travel on asymmetrical guide rails Ri and Ro respectively. At the outlet (position B in the figure) at the end of the stretching process, the held membrane is released. The membrane released from the gripping members Ci and Co is wound onto a core by the aforementioned membrane winding section 87.

[0289] Because guide rails Ri and Ro are asymmetrical, therefore... Figure 6 In the example, at position A in the figure, the left and right grips Ci and Co move along guide rails Ri and Ro, respectively, so that grip Ci, which moves on the inner side of guide rail Ri, is in a leading position relative to grip Co, which moves on the outer side of guide rail Ro.

[0290] That is, among the holding members Ci and Co at position A in the diagram, which are in directions approximately perpendicular to the film extraction direction D1, when one holding member Ci reaches position B where the film stretching is complete, the straight line connecting the holding members Ci and Co is tilted at an angle θL relative to the direction approximately perpendicular to the film winding direction D2. Through this action, the film substrate is stretched obliquely at an angle of θL relative to the width direction. Here, "approximately perpendicular" means within the range of 90±1°.

[0291] The heating zone Z of the stretching section 84 is composed of a preheating zone Z1, a stretching zone Z2, and a heat-fixing zone Z3. In the stretching section 84, the film held by the holding members Ci and Co passes sequentially through the preheating zone Z1, the stretching zone Z2, and the heat-fixing zone Z3. 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-fixing zone Z3 are also separated by a partition wall.

[0292] The preheating zone Z1 refers to the section in which the holding members Ci and Co at both ends of the membrane at the entrance of the heating zone Z move forward while maintaining a certain interval in the left and right (membrane width direction).

[0293] The stretching zone Z2 refers to the area where the spacing between the holding members Ci and Co at both ends of the film is opened to a specified interval. Oblique stretching, as described above, is then performed. Specifically, in the stretching zone Z2, an oblique stretching process is performed by stretching a long strip of film (film substrate) in an oblique direction relative to both the width and long side directions within the film surface to obtain an obliquely stretched film. It should be noted that longitudinal or transverse stretching can be performed before and after the oblique stretching, as needed.

[0294] The heat-fixing zone Z3 refers to the interval between the holding members Ci and Co after the stretching zone Z2, where the holding members Ci and Co at both ends move in a parallel manner. That is, in the heat-fixing zone Z3, a heat-fixing process is performed while conveying the obliquely stretched film with a constant width.

[0295] It should be noted that after the stretched film passes through the heat-fixing zone Z3, the temperature in the zone can be set to a range below the glass transition temperature Tg (°C) of the thermoplastic resin constituting the film (cooling zone). At this time, the guide pattern can be pre-set to narrow the gap between the opposing holding members Ci and Co, taking into account the shrinkage of the film due to cooling.

[0296] Relative to the glass transition temperature Tg of the thermoplastic resin, the temperature of the preheating zone Z1 is preferably set to Tg~Tg+30℃, the temperature of the stretching zone Z2 is preferably set to Tg~Tg+30℃, and the temperatures of the heat-fixing zone Z3 and the cooling zone are preferably set to Tg-30~Tg+20℃.

[0297] It should be noted that the lengths of the preheating zone Z1, the stretching zone Z2, and the heat-fixing zone Z3 can be appropriately selected. The length of the preheating zone Z1 is usually 100-150% of the length of the stretching zone Z2, and the length of the heat-fixing zone Z3 is usually 50-100%.

[0298] 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. If the stretching ratio is within this range, the thickness unevenness in the width direction of the film becomes smaller, which is therefore preferable. In the stretching zone Z2 of the oblique stretching tenter, if a difference in stretching temperature is imposed in the width direction, it is possible to make the thickness unevenness in the width direction more satisfactory. It should be noted that the stretching ratio R mentioned above is equal to the ratio (W / Wo) when the distance Wo between the two ends of the clamp held at the entrance of the tenter becomes the distance W at the exit of the tenter.

[0299] The thickness of the retardation film can be appropriately determined, generally considering factors such as optical properties, strength, workability, and thinness, and is preferably in the range of 1 to 500 μm. More preferably, the thickness of the retardation film is in the range of 5 to 100 μm, and even more preferably in the range of 15 to 80 μm.

[0300] [8] Manufacturing of polarizers

[0301] The polarizer layer and the polarizer protective film, as well as the polarizer layer and the retardation film, are preferably bonded, for example, by an adhesive layer described later. The adhesive layer can be a layer obtained by drying an aqueous adhesive, or a cured layer of an active linear curing adhesive. Additionally, the adhesive layer may contain a metallic compound filler.

[0302] [Adhesive layer]

[0303] An adhesive layer is arbitrarily disposed on the polarizer used in this invention. By having an adhesive layer, the workability of manufacturing an organic EL display device in which the polarizer is attached to the viewing side of the organic EL element is improved. Figure 3 The polarizer 10A shown in the cross-sectional view is an example of a polarizer having an adhesive layer. Polarizer 10A has an adhesive layer on the side of the retardation film opposite to the polarizer layer.

[0304] The type of adhesive used to form the adhesive layer is not particularly limited. Examples include rubber-based adhesives, acrylic adhesives, silicone adhesives, polyurethane adhesives, vinyl alkyl ether adhesives, polyvinyl alcohol adhesives, polyvinylpyrrolidone adhesives, polyacrylamide adhesives, and cellulose adhesives. Among these adhesives, acrylic adhesives are preferred due to their excellent optical transparency, suitable adhesion and cohesiveness, and superior durability and heat resistance. In this invention, acrylic adhesives containing a (meth)acrylic polymer as the base polymer are preferred.

[0305] There are no particular limitations on the method for forming the adhesive layer, and it can be formed using methods commonly used in the art. Specifically, an adhesive composition containing the above-mentioned adhesive or its raw materials and solvent can be coated onto at least one side of a substrate, and the coating formed by the adhesive composition can be dried, or it can be formed by irradiation with active rays such as ultraviolet light. In the case of an acrylic adhesive, the adhesive composition contains monomers, polymerization initiators, and solvents as structural units of the polymer.

[0306] The substrate for coating the adhesive composition is, for example, a release film or a retardation film. When forming the adhesive layer on the release film, the formed adhesive layer is transferred to the retardation film, and the release film is then peeled off. It should be noted that the release film can protect the adhesive layer until the polarizer 10B is made available for practical use.

[0307] The thickness of the adhesive layer is not particularly limited, but is preferably about 10 to 75 μm, and more preferably about 12 to 50 μm.

[0308] [Adhesive layer]

[0309] The polarizer layer and the polarizer protective film, as well as the polarizer layer and the phase retardation film, can also be bonded together, for example, via an adhesive layer. The adhesive layer can be a layer obtained by drying an aqueous adhesive, or a cured layer of an active radiation-curing adhesive. Furthermore, the adhesive layer may contain a metallic compound filler.

[0310] Examples of water-based adhesives include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl latex-based adhesives, water-based polyurethane adhesives, and water-based polyester adhesives. Specifically, examples of polyvinyl alcohol-based adhesives include fully saponified polyvinyl alcohol aqueous solutions (water paste). Examples of radiation-cured adhesives include ultraviolet-cured adhesives and electron beam-cured adhesives.

[0311] [Other functional layers of polarizers]

[0312] As another implementation of polarizers, such as Figure 2 The polarizer 10B shown has a hard coating layer, which is obtained by stacking the hard coating layer 4, the polarizer protective film 1, the polarizer layer 2, and the phase difference film 3 from the viewing side.

[0313] (Hard coating)

[0314] The hard coating 4 preferably exhibits a hardness of "HB" or higher in the pencil hardness test specified in JISK 5600-2014, and is preferably a cured product containing an active ray-curing resin to obtain this hardness. As the active ray-curing resin, it is preferable to use a component containing monomers having olefinic unsaturated double bonds. Examples of active ray-curing resins include ultraviolet-curing resins and electron beam-curing resins, but from the perspective of excellent film mechanical strength (scratch resistance, pencil hardness), a resin cured by ultraviolet irradiation is preferred.

[0315] Acrylic materials are preferred as the active radiation-curable resin. Among the acrylic materials, monofunctional or polyfunctional (meth)acrylate compounds such as (meth)acrylates of polyols, and polyfunctional urethane (meth)acrylate compounds synthesized from diisocyanates, polyols, and hydroxyl esters of (meth)acrylates can be used. In addition, polyether resins, polyester resins, epoxy resins, alkyd resins, spiroacetal resins, polybutadiene resins, and polythiol polyene resins having acrylate functional groups can also be used.

[0316] UV-curable acrylate resins, UV-curable polyurethane acrylate resins, UV-curable polyester acrylate resins, UV-curable epoxy acrylate resins, UV-curable polyol acrylate resins, or UV-curable epoxy resins are particularly preferred, with UV-curable acrylate resins being the most preferred.

[0317] Hard coatings are formed, for example, by using a hard coating forming composition containing an active radiation-curable resin, a polymerization initiator, and a solvent. Preferably, the solvent contained in the hard coating forming composition is a solvent that dissolves or swells the polarizer protective film or, in the case where the polarizer protective film has a primer layer described later. By dissolving or swelling the polarizer protective film or primer layer with the solvent, the hard coating forming composition can easily penetrate from the surface of the polarizer protective film or primer layer into the interior, thereby improving the adhesion between the polarizer protective film or primer layer and the hard coating.

[0318] In addition, a layer is formed near the surface of the polarizer protective film or primer layer, in which the resin components of the polarizer protective film or primer layer and the resin components of the hard coating layer are mixed. Through the action of this layer, a gradient in refractive index can be generated between the polarizer protective film or primer layer and the hard coating layer, which can prevent the generation of uneven interference.

[0319] Alternatively, the composition for forming a hard coating may contain conventionally known microparticles, dispersants, surfactants, antistatic agents, silane coupling agents, tackifiers, anti-coloring agents, colorants (pigments, dyes), defoamers, leveling agents, flame retardants, adhesive binders, polymerization inhibitors, antioxidants, surface modifiers, etc., to achieve purposes such as increasing the hardness of the hard coating, inhibiting curing shrinkage, preventing adhesion, controlling the refractive index, imparting anti-glare properties, and controlling the surface properties of the hard coating. Furthermore, the aforementioned composition for forming a hard coating may contain photosensitizers; specific examples include n-butylamine, triethylamine, and polyn-butylphosphine.

[0320] The hard coating is particularly preferably composed of microparticles. The preferred content of the microparticles is a microparticle:reactive radiation-curable resin ratio of 100:100 to 400:100. By including microparticles in this content, the dimensional variation of the hard coating can be reduced. There are no particular limitations on the microparticles, but microparticles composed of metal oxides (hereinafter also referred to as "metal oxide particles") are preferred. Examples of metal oxides include silicon dioxide, aluminum oxide, zirconium oxide, titanium oxide, and antimony pentoxide. Among these, the metal oxide particles are preferably composed of silicon dioxide. The silicon dioxide particles may also be hollow particles with internal cavities.

[0321] The aforementioned microparticles are preferably coated with a polymeric silane coupling agent. By coating the surface of the microparticles with a polymeric silane coupling agent, the microparticles can be uniformly dispersed in the composition for forming a hard coating. The average particle size of the microparticles coated with the polymeric silane coupling agent is preferably 5 to 500 nm, more preferably 10 to 200 nm. By using microparticles with such an average particle size, the optical properties of the hard coating can be improved.

[0322] The aforementioned polymeric silane coupling agent is prepared by reacting a polymerizable monomer with a silane coupling agent (a reactive silane compound). Examples of polymerizable monomers include monomers having an alkene-type unsaturated double bond, preferably monomers selected from (meth)acrylic acid and its derivatives. Examples of reactive silane compounds include hydrolyzable silane compounds having three alkoxy groups and one functional group bonded to the silicon atom. Examples of functional groups bonded to the silicon atom include groups having one or more groups selected from (meth)acryloyloxy, epoxy (glycidyl), carbamate, amino, fluorine, and mercapto.

[0323] Polymer silane coupling agents can be prepared, for example, according to the method for preparing a reactant of a polymeric 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, converted to polystyrene, is preferably 2,500 to 150,000, more preferably 2,000 to 100,000.

[0324] The method of coating the surface of silica particles with a polymer silane coupling agent will be described using silica microparticles as an example. First, a dispersion in which silica microparticles and a polymer silane coupling agent are dispersed in an organic solvent is prepared. An alkali is added to the dispersion to generate hydroxyl groups on the surface of the silica microparticles, allowing the polymer silane coupling agent to be adsorbed onto these hydroxyl groups. Alternatively, the hydroxyl groups can be bonded to the hydroxyl groups of the polymer silane coupling agent through a dehydration reaction. Finally, the silica microparticles adsorbed or bonded with the polymer silane coupling agent are separated from the dispersion and dried, thereby obtaining silica microparticles coated with the polymer silane coupling agent.

[0325] As for the preparation method of the above-mentioned hard coating forming composition, there is no particular limitation as long as the solid components contained in the hard coating can be uniformly mixed in the solvent. For example, the above-mentioned solid components and solvent can be mixed or dissolved using known devices such as paint shakers, bead mills, kneaders, and mixers.

[0326] The hard coating forming composition is applied to the surface of a polarizing protective film or a primer layer, and the active ray-curable resin in the coating film is cured to form a hard coating. Conventionally known methods can be used without particular limitation as the coating method for the hard coating forming composition. For example, microgravure coating is preferred when forming a uniform thin film layer, and mold coating is preferred when forming a thick film layer. After removing the solvent from the coating film as needed, the active ray-curable resin is cured by irradiation with active rays to obtain the hard coating.

[0327] The thickness of the hard coating is preferably in the range of 0.01 to 20 μm, and more preferably in the range of 0.5 to 10 μm, based on the average thickness.

[0328] (Primer layer)

[0329] As the material constituting the primer layer, any material capable of improving the adhesion and bonding between the polarizer protective film and the hard coating or polarizer layer can be used. Furthermore, in addition to adhesion and bonding properties, excellent transparency and thermal stability are preferred as characteristics of the material. Examples of such materials include resins composed of polyurethane, polyolefins, polyesters, polyvinylidene chloride, acrylic polymers, modified silicone polymers, styrene-butadiene rubber, carbodiimide compounds, and isocyanates.

[0330] The aforementioned 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 set according to the purpose. For example, the amount of additive used relative to 100 parts by weight of the total solids content in the primer layer is preferably 30 parts by weight or less, and more preferably 20 parts by weight or less.

[0331] As the material constituting the above-mentioned primer layer, the resin mentioned above is preferably a resin with polyurethane as the main component. Specific examples of polyurethane include: DIC Corporation's "HYDRAN Series" AP-201, AP-40F, HW-140SF, WLS-202; Daiichi Kogyo Pharmaceutical Co., Ltd.'s "SuperFlex Series" SF-210, SF460, SF870, SF420, SF-420NS; Mitsui Chemicals Co., Ltd.'s "TAKELAC Series" 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, WF-764; and ADEKA Corporation's "SPX-0882" product. It should be noted that resins such as polyurethanes with carboxyl groups on the side chains can be produced by isocyanate, Crosslinking agents such as zozoline and carbodiimide are used to crosslink the primer layer, thereby increasing its strength.

[0332] Optical properties of polarizers

[0333] In the polarizers used in this invention, the transmittance of the layer containing the pigment compound (compound (D)) of this invention is preferably within the following range.

[0334] (i) Transmittance of the layer containing compound (D)

[0335] The 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. Because the transmittance at a wavelength of 390 nm is within the above range, incident ultraviolet light can be blocked to a greater extent, thus significantly suppressing the degradation of the organic EL element, which is therefore preferred.

[0336] Furthermore, the transmittance of the layer containing compound (D) at a wavelength of 410 nm is preferably 60% or less, more preferably 50% or less, and even more preferably 40% or less. Since the transmittance at a wavelength of 410 nm is within the above-mentioned range, incident ultraviolet light can be blocked to a greater extent, thus significantly suppressing the degradation of the organic EL element, which is therefore preferable.

[0337] Furthermore, the transmittance of the layer containing compound (D) at a wavelength of 430 nm is preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more. Since the transmittance at a wavelength of 430 nm is within the above-mentioned range, sufficient light emission from the organic EL element can be transmitted, ensuring adequate display performance in the organic EL display device, and is therefore preferred.

[0338] (ii) Transmittance of polarizer

[0339] In the polarizer used in this invention, the 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 transmittance at a wavelength of 400 nm is preferably 20% or less, more preferably 15% or less, and more preferably 10% or less.

[0340] By using a polarizer with transmittance of 380 nm and 400 nm within the aforementioned range, incident ultraviolet light can be blocked to a greater extent. Therefore, when the polarizer is used in an organic EL display device, incident ultraviolet light can be blocked to a greater degree.

[0341] Furthermore, the transmittance of the polarizer used in this invention at a wavelength of 450 nm is preferably 25% or more, preferably 30% or more, and more preferably 33% or more. With a transmittance at a wavelength of 450 nm within the above range, when used in an organic EL display device, sufficient light emission from the organic EL element can be transmitted, ensuring adequate display performance in the organic EL display device, and is therefore preferred.

[0342] [9] Organic EL display device

[0343] The polarizer equipped with the polarizer protective film of the present invention can be used in various display devices such as liquid crystal display (LCD), organic EL display (OLED), and touch panel. The polarizer of the present invention is particularly preferred as a circular polarizer for organic EL display devices.

[0344] exist Figure 3 The diagram shows a cross-sectional view of an example configuration of an organic EL display device equipped with the polarizer protective film of the present invention. Figure 3 The illustrated organic EL display device 20 has an organic EL element 11 and a polarizer 10A or 10B of the present invention on its viewing side. 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.

[0345] The organic EL display device 20 can display an image by emitting light through the light-emitting layer when energized between the light-reflecting electrode and the transparent electrode layer. Furthermore, all light incident on the organic EL display device from the outside is absorbed by the polarizer layer 2 of the polarizer 10A or 10B, so even if it is reflected by the light-reflecting electrode of the organic EL element 11, it will not be emitted to the outside, thus suppressing the degradation of display characteristics caused by background reflection.

[0346] In the organic EL display device 20, the polarizing protective film preferably contains compound (D) and further contains an ultraviolet absorber.

[0347] Therefore, by placing a polarizer containing a polarizer protective film with pigment compounds, antioxidants, and microparticles on the viewing side of an organic EL element, the polarizer can fully absorb light with wavelengths shorter than the wavelength side of the emitting region of the organic EL element (the long wavelength side longer than 430 nm), protecting the organic EL element from outdoor light. Furthermore, by arranging the polarizer protective film containing pigment compounds, antioxidants, and microparticles in the specific order described above, internally generated heat is easily released from the surface of the polarizer protective film to the outside. This also has the advantage of suppressing degradation such as changes in the optical value of the retardation film caused by the heating of the compound (D) and the ultraviolet absorber, and degradation such as shrinkage of the polarizer layer.

[0348] Example

[0349] The present invention will be specifically described below with reference to specific embodiments, but the present invention is not limited thereto. It should be noted that the expressions "parts" or "%" used in the embodiments mean "parts by mass" or "% by mass" unless otherwise specified.

[0350] Example 1

[0351] (Determination of maximum absorption wavelength)

[0352] The maximum absorption wavelength of the pigment compound used in the examples (hereinafter referred to as compound (D)) was determined by measuring the absorption spectrum of the pigment compound in chloroform using a UV-2450 UV-Vis spectrophotometer manufactured by Shimadzu Corporation, and is recorded in Table I. In the table, "compound 1" refers to a compound having the structure represented by Formula 1 of the present invention.

[0353] It should be noted that the "maximum absorption wavelength" in this invention refers to the wavelength (nm) at which the absorption spectrum of the above-mentioned compound exhibits the maximum and highest absorbance (absorption intensity) when the absorption spectrum of the compound is measured.

[0354] Table I

[0355]

[0356] It should be noted that the structures of comparative compounds 1–3 as described in Table I are shown below.

[0357]

[0358] [1] Fabrication of polarizing protective film

[0359] <Polarizing Film 101: Fabrication of Cycloolefin Resin Film>

[0360] (Preparation of coatings)

[0361] A coating with the following composition was prepared. First, dichloromethane and ethanol were added to a pressure dissolving tank. While stirring, a cyclic olefin resin (COP), namely ARTON G7810 (manufactured by JSR Corporation, ARTON G7810, Mw: 140,000, a cyclic olefin resin with carboxylic acid groups), and compound 1 as compound (D) were added to the pressure dissolving tank containing the mixed solution of dichloromethane and ethanol. Then, 15 minutes after the solvent addition began, the particulate additive liquid prepared below was added, and the mixture was heated to 80°C and completely dissolved while stirring. At this point, the temperature was increased from room temperature at 5°C / min, dissolved for 30 minutes, and then cooled at 3°C / min. The resulting solution was filtered using Anji Filter Paper No. 244 manufactured by Anji Filter Paper Co., Ltd., to prepare the coating.

[0362] (Composition of paint)

[0363]

[0364]

[0365] (Filming of polarizing protective film 101)

[0366] The obtained coating is kept at 30°C and uniformly cast onto a stainless steel strip, which is also kept at 30°C as a metal support. The cast coating is then dried until the residual solvent content is 30% by mass, and then peeled off from the stainless steel strip to obtain a film.

[0367] 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 by a stretching ratio of 1.4 times (40%). Then, the obtained film was further dried at 150°C while being conveyed by multiple rollers to obtain a polarizer protective film 101 with a length of 3000m and a thickness of 20μm.

[0368] <Fabrication of Polarizing Protective Film 102>

[0369] In the fabrication of polarizer protective film 101, the following coating is used; otherwise, polarizer protective film 102 is fabricated in the same manner.

[0370] (Composition of paint)

[0371]

[0372] <Fabrication of Polarizing Protective Film 103>

[0373] In the fabrication of polarizer protective film 101, the following coating is used; otherwise, polarizer protective film 103 is fabricated in the same manner.

[0374] (Composition of paint)

[0375]

[0376]

[0377] (Silica dispersion)

[0378] First, 10 parts by weight of AEROSIL R812 (trade name, manufactured by AEROSIL Co., Ltd., Japan) and 90 parts by weight of ethanol were mixed in a dissolver for 30 minutes. Then, silica was dispersed in the ethanol using a homogenizer (Manton Gaulin). While stirring, 88 parts by weight of dichloromethane were added to the dispersion, and the mixture was stirred in the dissolver for 30 minutes to dilute the dispersion. The diluted dispersion was then filtered through a microparticle dispersion diluent filter (ADVANTEC Toyo Co., Ltd.: Polypropylene wound cartridge filter TCW-PPS-1N) to obtain a silica dispersion.

[0379] <Fabrication of Polarizing Protective Film 104>

[0380] In the fabrication of polarizer protective film 101, the following coating is used; otherwise, polarizer protective film 104 is fabricated in the same manner.

[0381] (Composition of paint)

[0382]

[0383] <Fabrication of Polarizing Protective Film 105-107>

[0384] In the fabrication of polarizer protective films 102 to 104, the antioxidant listed in Table II was changed to Irganox 1010 (manufactured by BASF Japan Co., Ltd.), and the microparticles were changed to R972. Otherwise, polarizer protective films 105 to 107 were fabricated in the same manner.

[0385] <Fabrication of Polarizing Protective Film 108: Fabrication of Cellulose Ester Resin Film>

[0386] (Preparation of coatings)

[0387] The coating with the following composition was prepared by first adding dichloromethane and ethanol to a pressurized dissolving tank. Then, cellulose ester was added to the pressurized dissolving tank containing the solvent while stirring, and the mixture was heated and stirred until completely dissolved.

[0388] (Composition of paint)

[0389]

[0390] The above-mentioned additive components were further added to a sealed container and dissolved while stirring. The solution was then filtered using Anji Filter Paper No. 244 manufactured by Anji Filter Paper Co., Ltd. to prepare a coating.

[0391] It should be noted that polyester compound N and polyester compound M are prepared as follows.

[0392] (Ester compound N)

[0393] First, 251 g of 1,2-propanediol, 354 g of terephthalic acid, 680 g of p-methylbenzoic acid, and 0.191 g of tetraisopropyl titanate (as an esterification catalyst) were added to a 2 L four-necked flask equipped with a thermometer, stirrer, and slow cooling tube. Next, a nitrogen stream was blown into the flask, and the solution was slowly heated to 230 °C while stirring. The degree of polymerization was observed during the dehydration condensation reaction. After the reaction was complete, unreacted 1,2-propanediol was distilled off under reduced pressure at 200 °C to obtain polyester compound N. This ester compound N has an acid value of 0.30 and a number-average molecular weight of 400.

[0394] (Ester compound M)

[0395] First, 251 g of 1,2-propanediol, 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 added to a 2 L four-necked flask equipped with a thermometer, stirrer, and slow cooling tube. Next, a nitrogen stream was blown into the flask, and the solution was slowly heated to 230 °C while stirring. The degree of polymerization was observed during the dehydration condensation reaction. After the reaction was complete, unreacted 1,2-propanediol was distilled off under reduced pressure at 200 °C to obtain the polyester compound M. Compound M has an acid value of 0.10 and a number-average molecular weight of 450.

[0396] (Filming of polarizing protective film 108)

[0397] The prepared coating was uniformly cast onto a stainless steel strip support at a temperature of 22°C and a width of 1.8m using a strip casting apparatus. The solvent was evaporated on the stainless steel strip support until the residual solvent content was 20%, and then the coating film (wet film) was peeled off from the stainless steel strip support.

[0398] Next, the peeled wet film was evaporated at 35°C to remove the solvent, cut into 1.6m wide pieces, and then stretched at 160°C in the width direction (TD direction) by 1.1 times the original width using a tenter frame. At this point, the residual solvent content at the start of the stretching process was 4% by mass.

[0399] Then, the film is dried while being conveyed by multiple rollers in a drying zone at 120°C and 140°C. It is then cut into 1.3m wide pieces, and knurled at both ends with a width of 10mm and a height of 2.5μm before being wound onto a core to produce the polarizing protective film 108. The polarizing protective film 108 has a thickness of 25μm and a winding length of 6000m.

[0400] <Fabrication of Polarizing Protective Film 109>

[0401] In the fabrication of polarizing protective film 108, the following coating is used; otherwise, polarizing protective film 109 is fabricated in the same manner.

[0402] (Composition of paint)

[0403]

[0404] <Fabrication of Polarizing Protective Film 110>

[0405] In the fabrication of polarizing protective film 108, the following coating is used; otherwise, polarizing protective film 110 is fabricated in the same manner.

[0406] (Composition of paint)

[0407]

[0408]

[0409] <Fabrication of Polarizing Protective Film 111>

[0410] In the fabrication of polarizing protective film 108, the following coating is used; otherwise, polarizing protective film 111 is fabricated in the same manner.

[0411] (Composition of paint)

[0412]

[0413] <Polarizing Film 112: Fabrication of Acrylic Resin Film>

[0414] A coating with the following composition was prepared. First, dichloromethane and ethanol were added to a pressurized dissolving tank. Next, resin was added to the pressurized dissolving tank while stirring. Then, the prepared rubber particle dispersion was added and stirred until completely dissolved. The solution was filtered using an SHP150 filter manufactured by ROKI TECHNO Co., Ltd. to obtain the coating.

[0415] (Composition of paint)

[0416]

[0417] The (meth)acrylic resin used above is a copolymer of methyl methacrylate (MMA) / N-phenylmaleimide (PMI) / butyl acrylate (BA) (80 / 10 / 10 mass ratio), Tg: 120℃, Mw: 2 million.

[0418] It should be noted that the glass transition temperature (Tg) of the acrylic resin was determined using DSC (Differential Scanning Colorimetry) according to JIS K7121-2012.

[0419] In addition, the weight-average molecular weight (Mw) of the acrylic resin was determined using a gel permeation chromatography system (Tosoh HLC8220GPC) and a column (Tosoh TSK-GELG6000HXL-G5000HXL-G5000HXL-G4000HXL-G3000HXL tandem). 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 (temperature 40 °C), and the determination was performed at a detector RI temperature of 40 °C. The value was converted using styrene.

[0420] The rubber particle dispersion used above was obtained by mixing 10 parts by weight of acrylic rubber particles M-210 (a core-shell type rubber particle with a multi-layered acrylic rubber polymer core and a methacrylate polymer with methyl methacrylate as the main component, the Tg of the acrylic rubber polymer is about -10℃, and the average particle size is 220nm) and 190 parts by weight of dichloromethane in a dissolver for 50 minutes, and then dispersing it using a Milder disperser (manufactured by Taihei Kiko Co., Ltd.) at 1500 rpm.

[0421] It should be noted that 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 and particle size measurement system (ELSZ-2000ZS manufactured by Otsuka Electronics Co., Ltd.).

[0422] <Fabrication of Polarizing Protective Film 113>

[0423] In the fabrication of polarizing protective film 112, the following coating is used; otherwise, polarizing protective film 113 is fabricated in the same manner.

[0424] (Composition of paint)

[0425]

[0426] <Fabrication of Polarizing Protective Film 114>

[0427] In the fabrication of polarizing protective film 112, the following coating is used; otherwise, polarizing protective film 114 is fabricated in the same manner.

[0428] (Composition of paint)

[0429]

[0430] <Fabrication of Polarizing Protective Film 115>

[0431] In the fabrication of polarizing protective film 112, the following coating is used; similarly, polarizing protective film 115 is also fabricated.

[0432] (Composition of paint)

[0433]

[0434] <Fabrication of Polarizing Protective Film 116-127>

[0435] In the fabrication of polarizer protective films 101-104 and 108-115, compound (D), i.e., compound 1, is replaced with comparative compounds 1, 2 and 3. Otherwise, polarizer protective films 116-127 are fabricated in the same manner.

[0436] [2] Fabrication of polarizers

[0437] <Fabrication of the polarizer layer>

[0438] A 25 μm thick polyvinyl alcohol (PVA) membrane was swollen in water at 35 °C. The resulting membrane was then immersed in an aqueous solution of 0.075 g iodine, 5 g potassium iodide, and 100 g water for 60 seconds, followed by immersion in an aqueous solution of 3 g potassium iodide, 7.5 g boric acid, and 100 g water at 45 °C. The resulting membrane was then uniaxially stretched at a stretching temperature of 55 °C and a stretching ratio of 5. After washing with water, the uniaxially stretched membrane was dried to obtain a 12 μm thick polarizer layer.

[0439] <Fabrication of the Phase Contrast Coating>

[0440] Polycarbonate resin film (PC film) is manufactured using the following method (melt casting film production method).

[0441] Polymerization was carried out using a batch polymerization unit consisting of two vertical reactors equipped with stirring blades and a reflux cooler controlled at 100°C. The molar ratios were BHEPF / ISB / DEG / DPC / MgAcetate = 0.348 / 0.490 / 0.162 / 1.005 / 1.00 × 10⁻⁶ -5 9,9-[4-(2-hydroxyethoxy)phenyl]fluorene (BHEPF), isosorbide (ISB), diethylene glycol (DEG), diphenyl carbonate (DPC), and magnesium acetate tetrahydrate were introduced. After thorough nitrogen replacement (oxygen concentration 0.0005–0.001 vol%), the reactor was heated by a heat transfer medium, and stirring was initiated when the internal temperature reached 100°C. Forty minutes after the initial heating, the internal temperature was increased to 220°C. While maintaining this temperature, the pressure was reduced, and after reaching 220°C, the pressure was lowered to 13.3 kPa over 90 minutes. Phenol vapor, a byproduct of the polymerization reaction, was introduced into a 100°C reflux cooler, allowing a certain amount of monomer components to return to the reactor. The non-condensable phenol vapor was then introduced into a 45°C condenser for recovery.

[0442] After temporarily pressurizing the reactor to atmospheric pressure by introducing nitrogen into the first reactor, the oligomerized reaction liquid in the first reactor was transferred to the second reactor. Next, the temperature and pressure in the second reactor were increased and decreased, reaching an internal temperature of 240°C and a pressure of 0.2 kPa within 50 minutes. Polymerization was then carried out until the specified stirring motive force was reached. At the moment the specified motive force was reached, nitrogen was introduced into the reactor for pressurization, and the reaction liquid was extracted in the form of a stream and granulated using a rotary cutter to obtain polycarbonate resin A, a copolymer of BHEPF / ISB / DEG = 34.8 / 49.0 / 16.2 [mol%). The reduced viscosity of polycarbonate resin A was 0.430 dL / g, and the glass transition temperature was 138°C.

[0443] After the obtained polycarbonate resin A was vacuum dried at 80°C for 5 hours, a film forming device equipped with a single-shaft extruder (manufactured by Isuzu Chemical Machinery Co., Ltd., screw diameter 25mm, barrel set temperature: 220°C), T-die (width 900mm, set temperature: 220°C), cold hardening roll (set temperature: 120~130°C) and a winding machine was used to form a roll of long strip film (film roll) of polycarbonate resin film with a thickness of 130μm.

[0444] The roll of the PC film 1 prepared above is placed in the inclined stretching film manufacturing apparatus 80 (see reference). Figure 5 , Figure 6 PC film 1 is extracted from the stretching section. Then, PC film 1 is heated to the preheating temperature by passing it through the preheating zone Z1 of the stretching section. Next, it is obliquely stretched at a stretch ratio of 3 times by passing it through the stretching zone Z2. Then, it is obliquely stretched into a PC film (λ / 4 sheet) with a thickness of 50 μm, a width of 1500 mm, and an orientation angle θ = 45° (value at the center of the width) by passing it through the heat-fixing zone Z3. The resulting obliquely stretched PC film is wound into a roll. It should be noted that the temperature T1 (preheating temperature) of the preheating zone Z1 of the stretching section is (Tg+15) °C, the temperature T2 (stretching temperature) of the stretching zone Z2 is (Tg+11) °C, and the temperature T3 of the heat-fixing zone Z3 is (Tg+9) °C.

[0445] <Making of Polarizing Sheets>

[0446] Polarizers 101 to 127 are fabricated by sequentially stacking the aforementioned polarizer protective films 101 to 127, the polarizer layer, and the phase retardation film. It should be noted that the phase retardation film and the polarizer layer, and the polarizer protective film and the polarizer layer, are bonded using a fully saponified polyvinyl alcohol aqueous solution (water paste).

[0447] "evaluate"

[0448] <1> Lightfastness test

[0449] Lightfastness tests were conducted on the polarizing protective films 101-127 prepared above.

[0450] The fabricated polarizing protective film was continuously irradiated with a xenon lamp (60W / m) for 100 hours. 2 The absorbance of the film before irradiation (0 hours) and after irradiation (100 hours) was measured using a spectrophotometer, and the pigment residue rate of compound (D) was determined according to the following formula (R).

[0451] Formula (R) Pigment Residue Rate (%) = {(A)} 100 ) / (A0)}×100

[0452] (Where, A0 is the absorbance before xenon lamp illumination, A...) 100 (This represents the absorbance after illumination by a xenon lamp.)

[0453] It should be noted that "absorbance" refers to the absorbance at the maximum absorption wavelength of each compound. The higher the pigment residue rate, the less easily the compound is decomposed by light, indicating higher lightfastness. Lightfastness is evaluated according to the following criteria.

[0454] A: The pigment residue rate is over 65%.

[0455] B: Pigment residue rate is 40% or higher but less than 65%.

[0456] C: Pigment residue rate is 10% or more but less than 40%.

[0457] D: Pigment residue rate is less than 10%.

[0458] <2> Durability: Evaluation of exudation

[0459] After placing each polarizer protective film in a high-temperature and high-humidity atmosphere of 60°C and 90%RH for 1000 hours, the presence or absence of exudation (crystal precipitation) on the surface of the polarizer protective film was visually observed, and the exudation was evaluated according to the criteria described below.

[0460] ◎: No seepage is visible on the surface of the polarizer protective film.

[0461] ○: Slight seepage is visible on the surface of the polarizer protective film.

[0462] △: Slight seepage is visible across the entire surface of the polarizer protective film.

[0463] ×: Clear seepage was observed across the entire surface of the polarizer protective film.

[0464] <3> Evaluation of light transmittance

[0465] The transmittance of the polarizing protective film prepared above was measured using a spectrophotometer (Hitachi High Technology U-3300) with varying measurement wavelengths (390 nm, 410 nm, and 430 nm). The results are shown in Table II.

[0466] The composition and evaluation results of the above polarizer protective films are shown in Table II.

[0467] Table II

[0468]

[0469] According to the evaluation results of the polarizing protective films shown in Table II, the polarizing protective films 101-115 using the pigment compounds of the present invention have excellent light resistance and exudation, and excellent cutoff of transmittance on the short wavelength side of visible light.

[0470] Furthermore, it is known that by adding antioxidants and microparticles in addition to pigment compounds, the light transmittance control of the polarizer protective film of the present invention is further improved.

[0471] Example 2

[0472] Using the polarizer protective film 101-127 prepared in Example 1, a primer layer is formed, a hard coating layer is formed, and an adhesive layer is provided on the side of the phase difference film opposite to the polarizer layer, and the organic EL element is bonded together to produce an organic EL display device.

[0473] (1) Formation of the primer layer

[0474] (Preparation of the primer coating liquid for the hard coating layer)

[0475] 100 parts by weight of thermosetting waterborne polyolefin resin (ArrowBase SB-1200 (trade name), 25% solids, manufactured by Uniqlo Co., Ltd.) and Eight parts by weight of a zopyridine crosslinking agent (WS-700, manufactured by Nippon Catalyst Co., Ltd.) were diluted with a diluent (water / methanol = 30 / 70 (by weight)) to a solid content concentration of 5%, and then stirred at room temperature to prepare primer coating solution 1.

[0476] (Formation of the hard coating side primer layer)

[0477] Using a bar coater, the prepared primer coating liquid 1 is applied to the side of the polarizer protective film 101-127 opposite to the polarizer layer side. The film is then dried in an oven at 80°C for 40 seconds to form a hard coating side primer layer with a dry film thickness of 0.4 μm.

[0478] (2) Formation of hard coating

[0479] (Formulation of compositions for hard coating)

[0480] Hard coating resin:

[0481] Pentaerythritol tri / tetraacrylate (NKESTER A-TMM-3L, trade name, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) 100 parts by weight

[0482] Photopolymerization initiator:

[0483] Irgacure 184 (trade name, manufactured by BASF Japan Co., Ltd.) 9 parts by weight

[0484] Solvent:

[0485] 20 parts by weight of propylene glycol monomethyl ether

[0486] 30 parts by weight of methyl acetate

[0487] 70 parts by weight of methyl ethyl ketone

[0488] additive:

[0489] Surfactant: KF-351A (trade name, polyether-modified silicone oil, manufactured by Shin-Etsu Chemical Co., Ltd.) 2 parts by weight

[0490] Microparticles: 100 parts by weight of polymer silane coupling agent coated silica

[0491] (Preparation of microparticles)

[0492] The above-mentioned polymeric silane coupling agent coated with silica was prepared as follows: 30 mL of methyl methacrylate (Kyoeisha Chemical Co., Ltd.: Lightester M), 1 mL of 3-mercaptopropyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd.: KBM-803), 100 mL of tetrahydrofuran as a solvent, and 50 mg of azoisobutyronitrile (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 polymeric silane coupling agent. The molecular weight of the obtained polymeric silane coupling agent was 16000. It should be noted that the molecular weight was determined by gel permeation chromatography.

[0493] Next, 100g of an ethanol dispersion of silica microparticles (SiO2 concentration 30% by mass) was prepared by ion exchange of silica sol (manufactured by Nichiki Catalyst Chemical Industry Co., Ltd.: Si-45P, trade name, SiO2 concentration 30% by mass, average particle size 45nm, dispersion medium: water) with ion exchange resin and by ultrafiltration membrane method to replace the solvent from water to ethanol.

[0494] 100g of the silica microparticle ethanol dispersion and 1.5g of the polymer silane coupling agent were dispersed in 20g (25mL) of acetone, and 20mg of ammonia water with a concentration of 29.8% by mass was added. The mixture was stirred at room temperature for 30 hours to allow the polymer silane coupling agent to be adsorbed onto the silica microparticles.

[0495] Then, silica particles with an average particle size of 5 μm were added, and the mixture was stirred for 2 hours to allow the unadsorbed polymer silane coupling agent in the solution to be adsorbed onto the silica particles. Next, the silica particles with an average particle size of 5 μm and adsorbed unadsorbed polymer silane coupling agent were removed by centrifugation. 1000 g of ethanol was added to the silica particle dispersion containing the adsorbed polymer silane coupling agent, causing the silica particles to settle and separate. The particles were then dried under reduced pressure and then 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.

[0496] (Formation of a hard coating)

[0497] The prepared hard coating composition was applied to the hard coating side primer layer of the polarizer protective film with a primer layer using a bar coater to achieve a dry film thickness of 2.5 μm. The mixture was then dried in a drying oven at 50°C for 40 seconds to evaporate the solvent. Following this, nitrogen purging was performed to create an atmosphere with an oxygen concentration of 1.0% by volume or less, and an ultraviolet lamp was used to irradiate the irradiated area at an illuminance of 100 mW / cm². 2 Set the irradiation dose to 0.2 J / cm². 2 The coating layer is then cured, thereby creating a polarizing protective film with a hard coating.

[0498] (3) Fabrication of organic EL display devices

[0499] The polarizer was fabricated using the polarizer protective film with hard coating, polarizer layer and phase difference film as described in Example 1. The polarizer was then bonded to the organic EL element by the adhesive layer after the release film was peeled off. Organic EL display devices 201 to 227 were fabricated and evaluated.

[0500] Specifically, the SAMSUNG GALAXY S10 (trade name) equipped with an organic EL panel is disassembled, and the circular polarizer is peeled off from the organic EL element. The polarizers 101 to 127 are then bonded to the peeled surface with the hard coating side as the viewing side and the phase difference film side as the organic EL element side, respectively, through an adhesive layer, to create an organic EL display device.

[0501] (Preparation of the adhesive composition)

[0502] In 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), 0.035 parts by mass of 1-hydroxycyclohexylphenyl ketone (trade name: Irgacure 184, manufactured by BASF Japan) and 0.035 parts by mass of 2,2-dimethoxy-1,2-diphenylethane-1-one (trade name: Irgacure 651, manufactured by BASF Japan) were added as photopolymerization initiators. After irradiation with ultraviolet light until the viscosity (measurement conditions: BH viscometer No.5 rotor, 10 rpm, measurement temperature 30°C) was approximately 20 Pa·s, a prepolymer composition (polymerization rate: 8%) was obtained by polymerizing a portion of the above monomer components. Next, 0.15 parts by weight of hexanediol diacrylate (HDDA) and 0.3 parts by weight of silane coupling agent (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) were added to the prepolymer composition and mixed to obtain an acrylic adhesive composition (a).

[0503] The adhesive composition was obtained by adding 0.2 parts by weight of phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (trade name: Irgacure 819, manufactured by BASF Japan Co., Ltd.) to the obtained acrylic adhesive composition (a) (with the monomer component forming the acrylic polymer set as 100 parts by weight), and stirring.

[0504] (Formation of the adhesive layer)

[0505] An adhesive composition was applied to the phase retardation film to a thickness of 150 μm after the adhesive layer was formed. Next, a release film was adhered to the surface of this adhesive composition layer. Then, an illumination of 6.5 mW / cm² was applied. 2 Light intensity: 1500 mJ / cm 2 The adhesive composition layer is photocured by ultraviolet irradiation under conditions of peak wavelength of 350nm to form an adhesive layer.

[0506] "evaluate"

[0507] <4> Evaluation of luminous loss

[0508] The transmittance was measured using a spectrophotometer (Hitachi High Technology U-3300) according to JIS K7375:2008 "Plastics - Method for determining total light transmittance and total light reflectance". It should be noted that a transmittance of 85% or higher is rated as "◎", 80% or higher but less than 85% is rated as "〇", and less than 80% is rated as "△". A transmittance of 80% or higher indicates low luminous loss.

[0509] <5> Lightfastness test

[0510] The lightfastness test was conducted on the organic EL display device fabricated above.

[0511] The fabricated organic EL display device was continuously irradiated with a xenon lamp (60W / m²) for 100 hours. 2 The luminescence intensity was measured before (0 hours) and after (100 hours) irradiation using light, and the change in luminescence intensity was measured according to the following formula 2.

[0512] The luminous intensity was measured as follows: at room temperature (25℃) at 2.5 mA / cm². 2 The luminance of each organic EL display device was measured using a CS-2000 spectroradiometer (manufactured by Konica Minolta Corporation) under constant current density conditions.

[0513] Equation 2: Luminous intensity change rate (%) = {(A)} 100 ) / (A0)}×100

[0514] (Where, A0 is the luminous intensity before xenon lamp illumination, A...) 100 (This refers to the luminous intensity after being illuminated by a xenon lamp.)

[0515] It should be noted that a higher value for the "luminance variation rate" indicates higher lightfastness of the display element. Lightfastness is evaluated according to the following criteria.

[0516] A: The rate of change in luminous intensity is over 90%.

[0517] B: The rate of change in luminous intensity is above 80% and less than 90%.

[0518] C: The rate of change in luminous intensity is greater than 70% and less than 80%.

[0519] D: The rate of change in luminous intensity is less than 70%.

[0520] The above layer composition and evaluation results are shown in Table III below.

[0521] Table I

[0522]

[0523] According to the evaluation results shown in Table III, the organic EL display devices 201-215 using the polarizing protective film of the present invention do not produce light loss, and the display elements have excellent light resistance.

[0524] Furthermore, based on the evaluation results shown in Tables II and III, it is confirmed that the polarizing protective film of the present invention is a polarizing protective film that can protect the display element from outdoor light, does not cause light loss to the light emission of the display element, has no leakage, and has excellent light resistance. It can provide polarizing films and organic EL display devices with excellent functionality and durability.

[0525] Example 3

[0526] <Fabrication of Polarizing Protective Film 301>

[0527] (Support structure)

[0528] As a support, a polyethylene terephthalate (PET) film is used: (TN100 manufactured by Toyobo Co., Ltd., with a release layer containing a non-silicone release agent, 38μm thick).

[0529] (Preparation of coating solution for polarizing protective film 301)

[0530] The following components are mixed to obtain a coating solution for substrate film 301.

[0531] First, dichloromethane and ethanol are added to a pressure dissolving tank. Cycloolefin resin (COP) is added to the pressure dissolving tank containing the dichloromethane and ethanol mixture while stirring. Then, 15 minutes after the solvent addition begins, the prepared particulate dispersion and compound (D), i.e., compound 1, are added, and the mixture is heated to 80°C while stirring until completely dissolved. The temperature is then increased from room temperature at 5°C / min, and after dissolving for 30 minutes, the temperature is decreased at 3°C / min. The resulting solution is filtered using Anji Filter Paper No. 244 manufactured by Anji Filter Paper Co., Ltd., to prepare a coating solution for polarizing protective film 301.

[0532] (Composition of the coating solution)

[0533]

[0534] (Fabrication of Polarizing Protective Film 301)

[0535] use Figure 4 The coating apparatus shown in the figure uses a support roller coating method to coat the polarizer protective film 301 with a coating solution onto the release layer of the support body using a die head. Then, the substrate film is dried in the following drying step to form a polarizer protective film with a thickness of 5 μm, thus obtaining the polarizer protective film 301.

[0536] Step 1: 1 minute at 40℃

[0537] Step 2: 1 minute at 70℃

[0538] Step 3: 1 minute at 100℃

[0539] Step 4: 2 minutes at 130℃

[0540] <Fabrication of Polarizing Protective Film 302>

[0541] In the fabrication of the polarizer protective film 301, after applying the coating solution of the polarizer protective film 301 using a die using a support roller coating method, the substrate film is dried in the above-mentioned drying step to prepare a polarizer protective film with a thickness of 10 μm.

[0542] <Fabrication of Polarizing Protective Film 303>

[0543] A resin composition was obtained by mixing 100 parts by mass of a cyclic olefin resin (ZEONOR, manufactured by Zeon Corporation of Japan, with a glass transition temperature Tg = 126°C) and 6 parts by mass of the following compound (a2) using a twin-screw extruder.

[0544] Next, a uniaxial extruder equipped with a gear pump and a filter is prepared, and the above-mentioned resin composition is fed into the uniaxial extruder to melt it. The molten resin composition is then passed through the gear pump and then through the filter, extruded from the T-die, and passed through the cooling roller to obtain a polarizing protective film 303 with a thickness of 10 μm.

[0545] (Synthesis of compound (a2): 6-(5-methylcarbonyloxyethyl-2H-benzotriazol-2-yl)benzo[1,3]dioxolane-5-ol)

[0546]

[0547] A 200 mL four-necked flask was fitted with a spherical condenser, thermometer, and stirrer. 2.0 g (0.0067 mol) of 6-(5-hydroxyethyl-2H-benzotriazol-2-yl)benzo[1,3]dioxolane-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. The mixture was refluxed at 110–115 °C for 4 hours to remove water. The mixture was washed three times with 50 mL of warm water, and 0.1 g of activated carbon was added. The mixture was then refluxed and stirred to remove color. The mixture was filtered while hot. The precipitated crystals were 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-benzotriazol-2-yl)benzo[1,3]dioxolane-5-ol was 96%.

[0548] In addition, the ultraviolet-visible absorption spectrum of compound (a2) was measured, and the maximum absorption wavelength was found to be 368 nm.

[0549] Using the obtained polarizing protective films, lightfastness, durability, and efflorescence were evaluated in the same manner as in Example 1. During the evaluation, polarizing protective films 301 and 302 were performed with the aforementioned support removed.

[0550] It can be seen that thin-film polarizer protective films 301 and 302 exhibit excellent lightfastness (“A”) and durability (exudation: “◎”), and the effects of the present invention can also be obtained in thin-film polarizer protective films. On the other hand, although polarizer protective film 303 has excellent lightfastness, an evaluation of 10 film samples showed that the exudation evaluation was in the range of “△~○”, and the durability was slightly worse.

[0551] Industrial availability

[0552] The polarizer protective film of the present invention is a polarizer protective film containing resin and pigment compounds. Since it can protect the display element from outdoor light, does not cause light loss to the light emission of the display element, has no leakage, and has excellent light resistance, it can be preferably used in display devices, especially organic electroluminescent display devices.

[0553] Symbol Explanation

[0554] 10A and 10B polarizers

[0555] 1. Polarizing film

[0556] 2 polarizer layers

[0557] 3 phase difference film

[0558] 4 Hard coating

[0559] 5 adhesive layers

[0560] 20 Organic EL Display Devices

[0561] 11 Organic EL Components

[0562] Manufacturing apparatus for 80-degree oblique stretched film

[0563] 81 Membrane Extraction Section

[0564] 82, 86 Conveyor Direction Change Section

[0565] 83 and 85 guide rollers

[0566] 84 stretching section

[0567] 87 Membrane winding section

[0568] B200 Manufacturing Facility

[0569] B210 Supply Department

[0570] B220 Coating Department

[0571] B230 Drying Section

[0572] B240 Cooling Section

[0573] B250 winding section

Claims

1. A polarizing protective film, characterized in that, Compounds containing the structure represented by Formula 1 below, Formula 1

Images