Composite polarizing plate and image display device

Abstract

To suppress the occurrence of reddening in a polarizing plate.SOLUTION: A composite polarizing plate 10 includes a polarizing plate 30 having a polarizer 31 in which a dichroic dye is adsorbed and oriented in a polyvinyl alcohol-based resin film, a first protective film 33 laminated on one surface of the polarizer 31, and a second protective film 34 laminated on the other surface of the polarizer 31. The composite polarizing plate 10 further includes an ammonia gas blocking layer 50, having an ammonia gas transmission concentration of 500 ppm or less, laminated on a surface opposite to the polarizer 31 on the first protective film 33. The composite polarizing plate 10 further includes an adhesive layer 42 laminated on a surface opposite to the polarizer 31 on the second protective film 34.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a composite polarizing plate and an image display device. [Background technology]

[0002] As described in Patent Document 1, it is known that a phenomenon called red discoloration occurs when a polarizing plate is placed in a high-temperature environment. Red discoloration is a phenomenon in which the transmittance on the long wavelength side of approximately 700 nm increases, causing the polarizing plate to appear red when placed in a crossed Nicol configuration. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-152862 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention aims to suppress the occurrence of red discoloration in a polarizing plate. The present inventors have found a correlation between the occurrence of red discoloration and contact between ammonia gas that has entered the polarizing plate from the outside and a polarizer. [Means for solving the problem]

[0005] The present invention includes the following inventions. [1] A composite polarizing plate including a polarizer having a polarizer in which a dichroic dye is adsorbed and oriented in a polyvinyl alcohol-based resin film, a first protective film laminated on one surface of the polarizer, and a second protective film laminated on the other surface of the polarizer, an ammonia gas blocking layer having an ammonia gas permeation concentration of 500 ppm or less is further laminated on the surface of the first protective film opposite to the polarizer, a composite polarizing plate further comprising a pressure-sensitive adhesive layer laminated on the surface of the second protective film opposite to the polarizer;

[0006] [2] The composite polarizing plate according to [1], wherein the ammonia gas blocking layer is a layer containing at least one selected from the group consisting of a cyclic olefin resin film and an acrylic resin film.

[0007] [3] The composite polarizing plate according to [1] or [2], wherein the polarizer and the first protective film, and the polarizer and the second protective film are laminated via an adhesive layer containing at least one urea compound selected from the group consisting of urea, urea derivatives, thiourea, and thiourea derivatives.

[0008] [4] The moisture permeability of the first protective film is 200 g / (m 2 The composite polarizing plate according to any one of [1] to [3], wherein the temperature is 24 hours or less.

[0009] [5] The composite polarizing plate according to any one of [1] to [4], wherein the first protective film and the ammonia gas blocking layer are laminated via an adhesive layer having a thickness of 10 μm or less.

[0010] [6] An image display device in which the composite polarizing plate according to any one of [1] to [5] and an image display panel are laminated, The image display device has the image display panel laminated on the surface of the second protective film opposite to the polarizer, with the pressure-sensitive adhesive layer interposed therebetween. [Effects of the Invention]

[0011] According to the present invention, it is possible to prevent red discoloration from occurring in the polarizing plate. [Brief explanation of the drawings]

[0012] [Figure 1]FIG. 1 is a schematic cross-sectional view showing a composite polarizing plate including polarizing plates. [Figure 2] FIG. 2 is a schematic cross-sectional view showing an image display device equipped with a composite polarizing plate. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the composite polarizing plate and the image display device will be described. <Composite polarizing plate> 1, composite polarizing plate 10 includes polarizing plate 30, ammonia gas blocking layer 50, and adhesive layer 42. Ammonia gas blocking layer 50 is laminated on polarizing plate 30, for example, via adhesive layer 41. Hereinafter, the ammonia gas blocking layer may be simply referred to as a blocking layer. Adhesive layer 42 is laminated on the surface of polarizing plate 30 opposite to the surface on which blocking layer 50 is laminated.

[0014] As will be described later, the composite polarizing plate 10 can be used as an image display device 20 as shown in FIG. 2 by bonding the adhesive layer 42 to an image display panel 60. The composite polarizing plate 10 can be a composite polarizing plate that is placed on the viewing side of the image display panel 60. In the composite polarizing plate 10, the side closer to the adhesive layer 42 is called the panel side, and the side closer to the blocking layer 50 is called the viewing side.

[0015] <Polarizing plate> The polarizing plate 30 includes a polarizer 31. The polarizing plate 30 includes a protective film that protects the polarizer 31.

[0016] As shown in FIG. 1, the polarizing plate 30 has a first protective film 33 laminated on one surface of a polarizer 31 via an adhesive layer 32. As shown in FIG. 1, the polarizing plate 30 has a second protective film 34 laminated on the other surface of the polarizer 31 via an adhesive layer 32. The first protective film 33 is a protective film laminated on the viewing side. The second protective film 34 is a protective film laminated on the panel side. The first protective film 33 and the second protective film 34 can be laminated using, for example, a roll laminator.

[0017] <Polarizer> The polarizer is a uniaxially stretched polyvinyl alcohol resin film to which a dichroic dye is adsorbed and aligned. The polyvinyl alcohol resin may be, for example, a saponified polyvinyl acetate resin. The saponification degree of the polyvinyl acetate resin is preferably 85 mol% or more, more preferably 90 mol% or more, and even more preferably 99 mol% or more.

[0018] Examples of polyvinyl acetate resins that can be used include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate with other copolymerizable monomers. Examples of the copolymerizable other monomers include unsaturated carboxylic acids, olefins, vinyl ethers, and unsaturated sulfonic acids.

[0019] The degree of polymerization of the polyvinyl alcohol resin is preferably 1,000 or more and 10,000 or less, and more preferably 1,500 or more and 5,000 or less. The polyvinyl alcohol resin may be modified. Examples of the modified polyvinyl alcohol resin include polyvinyl formal, polyvinyl acetal, and polyvinyl butyral modified with aldehydes.

[0020] Examples of the dichroic dye include iodine and water-soluble dichroic dyes. The thickness of the polarizer is not particularly limited, but is, for example, 1 μm or more, preferably 5 μm or more, more preferably 8 μm or more, and 50 μm or less, preferably 30 μm or less.

[0021] A known method can be used to manufacture a polarizer. For example, this manufacturing method involves sequentially performing a swelling step, a dyeing step, a crosslinking step, a washing step, and a drying step using a polyvinyl alcohol-based resin film as a raw film. The swelling step is a treatment step in which the raw film is immersed in a swelling liquid to swell it. The dyeing step is a treatment step in which the film after the swelling step is immersed in a dyeing liquid containing a dichroic dye to adsorb and align the dichroic dye in the film. The crosslinking step is a treatment step in which a crosslinking treatment is performed by bringing the film into contact with a crosslinking liquid. Between each step, i.e., before, after, or during any one or more of the treatment steps, a uniaxial stretching treatment can be performed as a stretching step.

[0022] The crosslinking step is a treatment step carried out for the purposes of imparting water resistance through crosslinking, adjusting hue (complementary color), etc. The crosslinking treatment may be carried out multiple times. When the crosslinking treatment is carried out multiple times, the crosslinking treatment for the purpose of imparting water resistance through crosslinking may be carried out multiple times, or the crosslinking treatment for the purpose of adjusting hue may be carried out multiple times. However, it is preferable to carry out the crosslinking treatment for the purpose of imparting water resistance through crosslinking at least once and the crosslinking treatment for the purpose of adjusting hue at least once, and it is more preferable to carry out the crosslinking step for the purpose of imparting water resistance through crosslinking after the crosslinking step for the purpose of adjusting hue.

[0023] The expression "at least one" used in this specification means "one or more" of the desired options. For example, when the number of options is three or more, the expression "at least one" used in this specification means "only one option" or "any combination of two or more options."

[0024] <Protective film> The protective film is not particularly limited, and various transparent protective films that can be used in polarizing plates can be employed. Examples of materials that can be used to form the protective film include thermoplastic resins that are excellent in transparency, mechanical strength, thermal stability, moisture barrier properties, and isotropy. Examples of the thermoplastic resins include cellulose ester resins such as triacetyl cellulose, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins such as nylon and aromatic polyamide, polyimide resins, polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymers, (meth)acrylic resins, cyclic polyolefin resins (norbornene resins) having a cyclo- or norbornene structure, polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. The protective film can also be a cured layer formed from a thermosetting resin or ultraviolet-curable resin, such as a (meth)acrylic, urethane, acrylic urethane, epoxy, or silicone resin. Among these, cellulose ester resins, polycarbonate resins, (meth)acrylic resins, cyclic polyolefin resins, and polyester resins are preferred.

[0025] The surface of the protective film to which the polarizer is not attached may be provided with a functional layer such as a hard coat layer, an antireflection layer, an antisticking layer, a diffusion layer, an antiglare layer, etc. The functional layer such as the hard coat layer, the antireflection layer, the antisticking layer, the diffusion layer, or the antiglare layer may be provided in the protective film itself, or may be provided separately as a layer separate from the protective film.

[0026] Either or both of the surface of the protective film to which the polarizer is attached and the surface of the polarizer to which the protective film is attached may be subjected to a surface treatment, such as a corona treatment, a plasma treatment, a primer treatment, or a saponification treatment.

[0027] The thickness of the protective film is not particularly limited, but from the viewpoint of ease of handling in the manufacturing process, it is 1 μm or more, preferably 10 μm or more, and more preferably 30 μm or more, and from the viewpoint of thinning the polarizing plate, it is 200 μm or less, preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 60 μm or less.

[0028] The moisture permeability of the protective film is not particularly limited, but the first protective film 33 on the viewing side of the protective film has a moisture permeability of, for example, 350 g / (m 2 The moisture permeability is, for example, 50 g / (m 2 The moisture permeability can be measured in accordance with the moisture permeability test (cup method) of JIS Z0208.

[0029] The moisture permeability is 50g / (m 2 ·24 hours) or more 350g / (m 2 24 hours) or less, and 80g / (m 2 ·24 hours) or more 300g / (m 2 24 hours) or less is more preferable, and 100g / (m 2 ·24 hours) or more 200g / (m 2 It is even more preferable that the time is 24 hours or less.

[0030] The ammonia gas permeation concentration of the protective film is not particularly limited, but the first protective film 33 on the viewing side of the protective films can have an ammonia gas permeation concentration of 1000 ppm or less. The ammonia gas permeation concentration of the first protective film 33 may be 800 ppm or less, 100 ppm or more, or 300 ppm or more. The ammonia gas permeation concentration related to the gas permeability of the first protective film 33 can be measured by the measurement method described below.

[0031] <Laminating layer> The attachment layer 32 may be a pressure-sensitive adhesive layer or an adhesive layer, and is preferably an adhesive layer.

[0032] As the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer, any conventionally known pressure-sensitive adhesive composition having excellent optical transparency can be used without particular limitation, and for example, a pressure-sensitive adhesive composition having a base polymer such as an acrylic resin, a urethane resin, a silicone resin, or a polyvinyl ether resin can be used. Among these, a pressure-sensitive adhesive composition having an acrylic resin as a base polymer is preferred, as it is excellent in transparency, adhesive strength, removability, weather resistance, heat resistance, etc. The pressure-sensitive adhesive composition may further contain a crosslinking agent, a silane compound, an antistatic agent, etc.

[0033] The adhesive composition forming the adhesive layer can be any of various adhesive compositions that can be used in polarizing plates, including aqueous adhesive compositions in which a curable adhesive component is dissolved or dispersed in water, and active energy ray-curable adhesive compositions containing an active energy ray-curable compound. Examples of aqueous adhesive compositions include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl latex-based adhesives, and aqueous polyesters. The adhesive composition is preferably an aqueous solution in which the adhesive component is dissolved in water, and the solids concentration of the adhesive composition is preferably 0.5 to 20% by mass, more preferably 1 to 15% by mass.

[0034] When a polyvinyl alcohol resin is used as the main component of the adhesive composition, the polyvinyl alcohol resin may be a polyvinyl alcohol resin such as a partially saponified polyvinyl alcohol or a fully saponified polyvinyl alcohol, or a modified polyvinyl alcohol resin. Examples of the modified polyvinyl alcohol resin include a carboxyl group-modified polyvinyl alcohol resin and an acetoacetyl group-modified polyvinyl alcohol resin.

[0035] The average degree of polymerization of the polyvinyl alcohol resin (preferably an acetoacetyl-modified polyvinyl alcohol resin) is preferably from 100 to 5,500, more preferably from 500 to 4,500, from the viewpoint of adhesiveness.

[0036] The degree of saponification of the polyvinyl alcohol resin (preferably an acetoacetyl-modified polyvinyl alcohol resin) is usually 80 mol % to 100 mol %, and preferably 85 mol % or more.

[0037] The degree of modification (amount of modification) with acetoacetyl groups in the acetoacetyl group-modified polyvinyl alcohol resin is usually 0.1 mol % to 40 mol %, preferably 0.5 mol % to 20 mol %, from the viewpoint of adhesiveness.

[0038] Among aqueous adhesive compositions, polyvinyl alcohol-based adhesive compositions are preferred, and acetoacetyl-modified polyvinyl alcohol-based adhesive compositions are more preferred. That is, the attachment layer 32 is preferably a cured layer of an aqueous adhesive composition containing a polyvinyl alcohol-based resin.

[0039] Examples of adhesive compositions include the aqueous adhesive compositions described above, as well as active energy ray-curable adhesive compositions such as ultraviolet-curable adhesive compositions and electron beam-curable adhesive compositions. Examples of active energy ray-curable adhesive compositions include (meth)acrylate adhesives. Examples of curable components in (meth)acrylate adhesives include compounds having a (meth)acryloyl group and compounds having a vinyl group. Examples of compounds having a (meth)acryloyl group include alkyl (meth)acrylates such as linear alkyl (meth)acrylates, alicyclic alkyl (meth)acrylates, and polycyclic alkyl (meth)acrylates having 1 to 20 carbon atoms; hydroxyl group-containing (meth)acrylates; and epoxy group-containing (meth)acrylates such as glycidyl (meth)acrylate. The (meth)acrylate adhesive may contain a nitrogen-containing monomer such as hydroxyethyl (meth)acrylamide, N-methylol (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, (meth)acrylamide, or (meth)acryloylmorpholine. The (meth)acrylate adhesive may contain a polyfunctional monomer as a crosslinking component, such as tripropylene glycol diacrylate, 1,9-nonanediol diacrylate, tricyclodecane dimethanol diacrylate, cyclic trimethylolpropane formal acrylate, dioxane glycol diacrylate, or EO-modified diglycerin tetraacrylate. Furthermore, compounds containing epoxy groups or oxetanyl groups can also be used as cationic polymerization-curable adhesives. The epoxy group-containing compound is not particularly limited as long as it has at least two epoxy groups in the molecule, and various commonly known curable epoxy compounds can be used.

[0040] The active energy ray-curable adhesive composition may contain appropriate additives as needed, such as coupling agents (e.g., silane coupling agents, titanium coupling agents), adhesion promoters (e.g., ethylene oxide), ultraviolet absorbers, antidegradants, dyes, processing aids, ion trapping agents, antioxidants, tackifiers, fillers, plasticizers, leveling agents, foam inhibitors, antistatic agents, heat stabilizers, and hydrolysis stabilizers.

[0041] The adhesive composition may be applied to either the protective film side or the polarizer side, or to both. After lamination, a drying step is performed to form an adhesive layer consisting of a dried coated layer. After the drying step, ultraviolet light or electron beams may be irradiated as necessary.

[0042] The adhesive composition forming the laminating layer 32 may contain a urea compound. The urea compound and other components that may be contained in the adhesive composition will be described below. [Urea compound] The urea compound is, for example, at least one selected from the group consisting of urea, urea derivatives, thiourea, and thiourea derivatives. One urea compound can be used alone, or two or more can be used in combination. Urea compounds include water-soluble and poorly water-soluble urea compounds, and either type can be used. When a poorly water-soluble urea compound is used in a water-soluble adhesive, it is preferable to devise a dispersion method to prevent an increase in haze after forming the adhesive layer. Urea is preferred as the urea compound.

[0043] (urea derivative) A urea derivative is a compound in which at least one of the four hydrogen atoms of a urea molecule is substituted with a substituent. In this case, the substituent is not particularly limited, but is preferably a substituent consisting of carbon, hydrogen, and oxygen atoms.

[0044] Specific examples of the urea derivatives include mono-substituted ureas such as methylurea, ethylurea, propylurea, butylurea, isobutylurea, N-octadecylurea, 2-hydroxyethylurea, hydroxyurea, acetylurea, allylurea, 2-propynylurea, cyclohexylurea, phenylurea, 3-hydroxyphenylurea, (4-methoxyphenyl)urea, benzylurea, benzoylurea, o-tolylurea, and p-tolylurea.

[0045] Examples of disubstituted ureas include 1,1-dimethylurea, 1,3-dimethylurea, 1,1-diethylurea, 1,3-diethylurea, 1,3-bis(hydroxymethyl)urea, 1,3-tert-butylurea, 1,3-dicyclohexylurea, 1,3-diphenylurea, 1,3-bis(4-methoxyphenyl)urea, 1-acetyl-3-methylurea, 2-imidazolidinone (ethyleneurea), and tetrahydro-2-pyrimidinone (propyleneurea).

[0046] Examples of 4-substituted ureas include tetramethylurea, 1,1,3,3-tetraethylurea, 1,1,3,3-tetrabutylurea, 1,3-dimethoxy-1,3-dimethylurea, 1,3-dimethyl-2-imidazolidinone, and 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone.

[0047] (thiourea derivatives) A thiourea derivative is a compound in which at least one of the four hydrogen atoms of a thiourea molecule is substituted with a substituent. In this case, the substituent is not particularly limited, but is preferably a substituent consisting of a carbon atom, a hydrogen atom, and an oxygen atom.

[0048] Specific examples of the thiourea derivatives include mono-substituted thioureas such as N-methylthiourea, ethylthiourea, propylthiourea, isopropylthiourea, 1-butylthiourea, cyclohexylthiourea, N-acetylthiourea, N-allylthiourea, (2-methoxyethyl)thiourea, N-phenylthiourea, (4-methoxyphenyl)thiourea, N-(2-methoxyphenyl)thiourea, N-(1-naphthyl)thiourea, (2-pyridyl)thiourea, o-tolylthiourea, and p-tolylthiourea.

[0049] Examples of disubstituted thioureas include 1,1-dimethylthiourea, 1,3-dimethylthiourea, 1,1-diethylthiourea, 1,3-diethylthiourea, 1,3-dibutylthiourea, 1,3-diisopropylthiourea, 1,3-dicyclohexylthiourea, N,N-diphenylthiourea, N,N′-diphenylthiourea, 1,3-di(o-tolyl)thiourea, 1,3-di(p-tolyl)thiourea, 1-benzyl-3-phenylthiourea, 1-methyl-3-phenylthiourea, N-allyl-N′-(2-hydroxyethyl)thiourea, and ethylenethiourea.

[0050] An example of the 3-substituted thiourea is trimethylthiourea, and an example of the 4-substituted thiourea is tetramethylthiourea or 1,1,3,3-tetraethylthiourea. The content of the urea compound in the adhesive composition is preferably within the following range, for example. For example, when the adhesive composition is an aqueous adhesive containing a polyvinyl alcohol-based resin, the content of the urea compound is preferably 0.1 to 400 parts by mass, more preferably 1 to 200 parts by mass, and even more preferably 3 to 100 parts by mass, per 100 parts by mass of the polyvinyl alcohol-based resin. The addition of the urea compound provides an effect of inhibiting polyenization in high-temperature environments, but if the amount of the urea compound is less than 0.1 part by mass per 100 parts by mass of the polyvinyl alcohol-based resin, this effect may be insufficient. If the amount of the urea compound is more than 400 parts by mass per 100 parts by mass of the polyvinyl alcohol-based resin, the urea compound may precipitate, causing problems such as increased haze.

[0051] [Other ingredients] The adhesive composition may contain an organic solvent. Alcohols are preferred as the organic solvent because they are miscible with water, and among alcohols, methanol or ethanol is more preferred. The concentration of the organic solvent in the aqueous adhesive is preferably 10% by mass or more and 70% by mass or less, more preferably 15% by mass or more and 60% by mass or less, and even more preferably 20% by mass or more and 60% by mass or less. Having an organic solvent concentration of 10% by mass or more makes it easier to suppress polyenation of the PVA resin in a high-temperature environment. Furthermore, having an organic solvent content of 70% by mass or less can suppress deterioration of color. Some of the urea derivatives described above have low solubility in water, but sufficient solubility in alcohol. In this case, one preferred embodiment is to dissolve a urea compound in alcohol to prepare an alcohol solution of the urea compound, and then add the alcohol solution of the urea compound to an aqueous PVA solution to prepare the adhesive.

[0052] The aqueous adhesive composition may contain a crosslinking agent. The crosslinking agent is typically a compound having at least two functional groups per molecule that are reactive with the polymer or other components that make up the adhesive. Examples of such crosslinking agents include alkylenediamines, isocyanates, epoxies, aldehydes, amino-formaldehydes such as methylol urea and methylol melamine, glyoxal, and glyoxal derivatives. The amount of crosslinking agent in the adhesive is typically about 5 to 60 parts by mass per 100 parts by mass of the polymer or other components that make up the adhesive.

[0053] The thickness of the attachment layer 32 is not particularly limited. For example, when an aqueous adhesive composition or the like is used, the thickness is preferably about 1 to 5,000 nm, and more preferably about 10 to 1,000 nm. For example, when an active energy ray-curable adhesive composition or the like is used, the thickness is preferably about 0.1 to 10 μm, and more preferably about 0.5 to 5 μm. For example, when a pressure-sensitive adhesive composition is used, the thickness is generally preferably 0.1 to 30 μm, more preferably 3 to 30 μm, and even more preferably 5 to 25 μm.

[0054] <Ammonia gas blocking layer> The ammonia gas blocking layer 50 is laminated on the surface of the first protective film 33 opposite to the polarizer 31 side.

[0055] The blocking layer 50 has an ammonia gas permeation concentration of 500 ppm or less. The ammonia gas permeation concentration of the blocking layer 50 is preferably 220 ppm or less, and more preferably 140 ppm or less. The lower the ammonia gas permeation concentration of the blocking layer 50, the more the red discoloration of the polarizing plate can be suppressed. The ammonia gas permeation concentration, which is related to the gas permeability of the blocking layer 50, can be measured by the measurement method described below.

[0056] The blocking layer 50 is not limited in other configuration as long as it is a layer whose ammonia gas permeation concentration is within the above-mentioned specific range. Examples of the blocking layer 50 include a layer made of a film such as a triacetyl cellulose film, an acrylic resin film, or a cyclic olefin resin film. The triacetyl cellulose film may have a hard coat layer. One or both surfaces of the film may be subjected to a surface treatment. Examples of surface treatments include corona treatment, plasma treatment, primer treatment, and saponification treatment.

[0057] The block layer 50 may have a single layer structure or a multi-layer structure of two or more layers. For example, when the multi-layer block layer 50 is formed of two or more films, the block layer 50 may include a pressure-sensitive adhesive layer interposed between the films. For example, the pressure-sensitive adhesive layer may be the same as the pressure-sensitive adhesive layer or adhesive layer exemplified in this specification. When the multi-layer block layer 50 is formed of films, only one type of film may be used, or two or more types of films may be used in combination.

[0058] The blocking layer 50 is preferably a layer containing at least one selected from the group consisting of a cyclic olefin resin film and an acrylic resin film. There are no particular limitations on the thickness of the blocking layer 50. The thickness of the blocking layer 50 is, for example, 5 μm or more and 100 μm or less, preferably 20 μm or more and 80 μm or less, and more preferably 13 μm or more and 50 μm or less.

[0059] The moisture permeability of the blocking layer 50 is not particularly limited. For example, the moisture permeability of the blocking layer 50 is 2 g / (m) in an environment of a temperature of 40°C and a relative humidity of 90%. 2 ·24 hours) or more 450g / (m 2 24 hours) or less, preferably 2 g / (m 2 ·24 hours) or more 350g / (m 2 24 hours) or less, and more preferably 2 g / (m 2 ·24 hours) or more 100g / (m 2 The moisture permeability of the blocking layer 50 is 5 g / (m 2The moisture permeability can be measured in accordance with the moisture permeability test (cup method) of JIS Z0208.

[0060] <Adhesive layer> The adhesive layer 41 is in direct contact with the first protective film 33 and the ammonia gas blocking layer 50, for example.

[0061] The adhesive layer 41 may be a pressure-sensitive adhesive layer or an adhesive layer. The pressure-sensitive adhesive layer or adhesive layer constituting the adhesive layer 41 can be appropriately selected from those described as the attaching layer 32. The thickness of the adhesive layer 41 is not particularly limited, but is preferably 0.015 μm or more and 25 μm or less, for example. The thickness of the adhesive layer 41 is preferably 0.015 μm or more and 15 μm or less, more preferably 0.015 μm or more and 10 μm or less, and most preferably 3 μm or more and 8 μm or less.

[0062] <Adhesive layer> The pressure-sensitive adhesive layer 42 is in direct contact with, for example, the second protective film 34. The pressure-sensitive adhesive layer 42 may be laminated via another layer that is laminated on the surface of the second protective film 34 opposite to the polarizer 31.

[0063] The adhesive composition forming the adhesive layer 42 can be appropriately selected from those described as the attachment layer 32. The thickness of the adhesive layer 42 is not particularly limited and is, for example, about 1 to 100 μm, and preferably about 2 to 50 μm.

[0064] <Image display device> FIG. 2 shows an example of the image display device 20. As shown in FIG. As shown in FIG. 2, the composite polarizing plate 10 can be used in an image display device 20.

[0065] The image display device 20 includes, for example, an image display panel 60. In the image display device 20, the image display panel 60 is laminated on the surface of the second protective film 34 opposite to the polarizer 31, with a pressure-sensitive adhesive layer 42 interposed therebetween.

[0066] Before being bonded to the image display panel 60, the composite polarizing plate 10 may have a film having a release treatment layer laminated on the pressure-sensitive adhesive layer 42 of the composite polarizing plate 10. The film having the release treatment layer is peeled off and removed when manufacturing the image display device 20. The pressure-sensitive adhesive layer 42 exposed by removing the film having the release treatment layer can be bonded to the image display panel 60. The release treatment layer may be any known release treatment layer, and examples thereof include a layer formed by coating a base film with a release agent such as a fluorine compound or a silicone compound.

[0067] The image display device 20 includes, for example, a transparent member 70. In the image display device 20, for example, the transparent member 70 is laminated on the blocking layer 50 of the composite polarizing plate 10 via the front bonding layer 43.

[0068] The front surface laminating layer 43 is, for example, a pressure-sensitive adhesive layer. The pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer can be appropriately selected from those described as the laminating layer 32. Examples of the transparent member 70 include a front transparent plate (window layer) and a touch panel. The front transparent plate is a transparent plate having appropriate mechanical strength and thickness. Examples of such transparent plates include transparent resin plates such as acrylic resins and polycarbonate resins, glass plates, and laminates thereof. Examples of touch panels include various types of touch panels such as resistive, capacitive, optical, and ultrasonic touch panels, as well as glass or transparent resin plates equipped with touch sensor functions.

[0069] The image display panel 60 is not particularly limited, and examples thereof include a liquid crystal display panel, an organic electroluminescence (organic EL) display panel, an inorganic electroluminescence (inorganic EL) display panel, a plasma display panel, and a field emission display panel.

[0070] Examples of applications of image display devices include televisions, personal computers, mobile devices such as mobile phones and tablet terminals, and in-vehicle applications, etc. Specific examples of in-vehicle applications include car navigation devices, speedometers, touch panels for air conditioners, back monitors, and rear monitors.

[0071] <Effects of this embodiment> When polarizing plates are placed in a high-temperature environment, red discoloration occurs, which is a problem. The more easily external ammonia gas penetrates the polarizing plate, the more likely the red discoloration occurs.

[0072] The composite polarizing plate and image display device of this embodiment include an ammonia gas blocking layer with an ammonia gas permeation concentration of 500 ppm or less on the viewing side of the polarizing plate. This prevents ammonia gas present or generated from the outside, i.e., on the viewing side of the polarizing plate, from penetrating the polarizing plate. This prevents red discoloration from occurring. The composite polarizing plate and image display device of this embodiment are less likely to cause red discoloration in the polarizing plate even when placed in a high-temperature environment.

[0073] The composite polarizing plate and image display device, which are resistant to red discoloration even in a high-temperature environment, can be suitably used in applications where they are exposed to a high-temperature environment for a long period of time. For example, image display devices for in-vehicle applications such as car navigation systems and rearview monitors are sometimes exposed to a high-temperature environment for a long period of time. The composite polarizing plate and image display device of this embodiment can also be suitably used in in-vehicle applications.

[0074] In this embodiment, "high temperature environment" means an environment of 100°C or higher, for example, 105°C or higher. Furthermore, "long period of time" means 100 hours or longer, for example, 120 hours.

[0075] The source of the external ammonia gas is not particularly limited, and examples of the external ammonia gas include ammonia gas present in the air and ammonia gas generated during storage, transportation, and use of the composite polarizing plate and the image display device. [Example]

[0076] The composite polarizing plate and the image display device will be described in more detail based on the following examples. Note that the composite polarizing plate and the image display device are not limited to the configurations described in the examples.

[0077] <Measurement of moisture permeability of film and film laminate> The moisture permeability of the film and film laminate used in the production of the composite polarizing plate was measured at a temperature of 40° C. and a relative humidity of 90% in accordance with the moisture permeability test (cup method) of JIS Z0208.

[0078] <Measurement of ammonia gas permeation concentration of film and film laminate> The ammonia gas permeation concentration of the film used in the production of the composite polarizing plate was measured by the following measurement method. The ammonia gas permeation concentration of the laminate of the films used in the production of the composite polarizing plate was measured by replacing the film in the following measurement method with the laminate.

[0079] 0.07 ml of 10% ammonia solution was placed in a cup conforming to the JIS L1099 moisture permeability test (cup method), and the permeable ammonia gas area was measured to be 28.26 cm 2 The cup was covered with a film processed to the desired shape. Next, the film was held down with an O-ring, and a wing nut was tightened to secure the cup and ring. Next, the cup was inserted into an aluminum-coated bag (capacity 1 liter), and the opening of the aluminum-coated bag was sealed with a heat seal. After leaving it at a temperature of 23°C for 2 hours, a gas detector tube manufactured by Gastec Corporation was inserted into the aluminum-coated bag to measure the ammonia gas concentration inside the aluminum-coated bag. The ammonia gas concentration inside the aluminum-coated bag is the concentration of ammonia gas that has leaked out of the cup through the film.

[0080] (Production Example 1: Preparation of polarizer) A 30 μm-thick polyvinyl alcohol resin film was immersed in pure water at 21.5°C for 79 seconds (swelling step), and then immersed in an aqueous solution at 23°C containing 1.0 mM iodine and having a potassium iodide / boric acid / water mass ratio of 2 / 2 / 100 for 151 seconds (dyeing step). The film was then removed from the aqueous solution and immersed in an aqueous solution at 68.5°C containing a potassium iodide / boric acid / water mass ratio of 2.5 / 4 / 100 for 76 seconds (first crosslinking step). The film was then removed from the aqueous solution and immersed in an aqueous solution at 45°C containing a potassium iodide / boric acid / zinc chloride / water mass ratio of 3 / 5.5 / 0.6 / 100 for 11 seconds (second crosslinking step, metal ion treatment step). The film was then removed from the aqueous solution and immersed in a cleaning solution for cleaning (cleaning step). The film was then removed from the cleaning solution and dried at 38°C (drying step) to obtain a 12µm thick polarizer in which iodine was adsorbed and oriented in the polyvinyl alcohol. Stretching was mainly performed in the dyeing step and the first crosslinking step, with a total stretching ratio of 5.85 times. The thickness of the obtained polarizer was measured using a digital micrometer "MH-15M" manufactured by Nikon Corporation.

[0081] (Production Example 2: Preparation of adhesive composition) 50 g of acetoacetyl group-modified polyvinyl alcohol resin (Mitsubishi Chemical Corporation: Gohsenex Z-410) was dissolved in 950 g of pure water, heated at 90°C for 2 hours, and then cooled to room temperature to obtain an acetoacetyl group-modified polyvinyl alcohol resin solution.

[0082] Maleic acid, a 40 mass% glyoxal solution, urea, and pure water were blended into the obtained acetoacetyl group-modified polyvinyl alcohol resin solution so as to have the contents shown in Table 1 below, to prepare adhesive composition 1. Furthermore, maleic acid, a 40 mass% glyoxal solution, and pure water were blended into the obtained acetoacetyl group-modified polyvinyl alcohol resin solution so as to have the contents shown in Table 1 below, to prepare adhesive composition 2.

[0083] [Table 1]

[0084] <Preparation of polarizing plate> The following films were prepared: Film F1: Saponified triacetyl cellulose film with a hard coat layer (manufactured by Toppan Printing Co., Ltd., product name "40FJCHCN-LMP", triacetyl cellulose film thickness: 40 μm, hard coat layer thickness: 7 μm). Moisture permeability is 200 g / (m 2 24 hours), the ammonia gas permeation concentration was 400 ppm. Film F2: A laminated retardation film described in WO 2022 / 158482

[0147] . This laminated retardation film comprises a liquid crystal layer (first retardation layer) and a cycloolefin polymer film (second retardation layer). Film F3: Acrylic resin film (manufactured by Toyo Kohan Co., Ltd.: product name "HX-40NE"). Thickness: 40 μm. Moisture permeability: 60 g / (m 2 24 hours), the ammonia gas permeation concentration was 10 ppm. Film F4: Cycloolefin polymer film (thickness 23 μm, manufactured by Zeon Corporation). Moisture permeability is 6 g / (m 2 24 hours), the ammonia gas permeation concentration was 220 ppm.

[0085] (Production Example 3: Preparation of Polarizing Plates 1 and 2) Film F1 was laminated to one side of the polarizer produced in Production Example 1 via adhesive composition 1 prepared in Production Example 2, with the side without the hard coat layer facing the polarizer. Film F2 was also laminated to the other side of the polarizer via adhesive composition 1 prepared in Production Example 2, with the first retardation layer facing the polarizer, so that the slow axis of the second retardation layer was parallel to the absorption axis of the polarizer, and the films were bonded using a roll laminator. This was then dried at 75°C for 8 minutes to obtain polarizing plate 1. Films F1 and F2 laminated to the polarizer corresponded to protective films protecting the polarizer. The adhesive layers made of adhesive composition 1 each had a thickness of 80 nm after drying.

[0086] Polarizing plate 2 was produced in the same manner as polarizing plate 1, except that adhesive composition 1 was replaced with adhesive composition 2. The adhesive layer made of adhesive composition 2 had a thickness of 80 nm after drying.

[0087] (Production Example 4: Preparation of adhesive sheet with adhesive layer) Adhesive sheet A: A sheet comprising a 38 μm polyethylene terephthalate (PET) film with a release agent on both sides of a commercially available sheet-like acrylic adhesive layer A. The thickness of adhesive layer A is 5 μm, and the storage modulus is 0.14 MPa. Adhesive sheet B: A sheet comprising a 38 μm PET film with a release agent on both sides of a commercially available sheet-shaped acrylic adhesive layer B. The thickness of adhesive layer B is 25 μm, and the storage modulus is 0.06 MPa.

[0088] (Example 1: Preparation of optical laminate 1) One of the release-agent-attached PET films in the pressure-sensitive adhesive sheet A was peeled off to expose the pressure-sensitive adhesive layer A, which was then bonded to the film F1 side of the polarizing plate 1 produced above, i.e., the surface on which the hard coat layer was exposed. Next, film F3 (acrylic resin film) was bonded to the pressure-sensitive adhesive layer A, which was exposed by peeling off the other release-agent-attached PET film in the pressure-sensitive adhesive sheet A. In this way, film F3 (acrylic resin film) was laminated on the film F1 side of the polarizing plate 1 via the pressure-sensitive adhesive layer A. Next, one of the release-agent-attached PET films in the pressure-sensitive adhesive sheet B was peeled off to expose the pressure-sensitive adhesive layer B, which was then bonded to the film F2 side of the polarizing plate 1, to produce an optical laminate 1 in which the pressure-sensitive adhesive layer B was laminated on the film F2 side of the polarizing plate 1. The obtained optical laminate 1 had a layer structure of "film F3 (acrylic resin film) / pressure-sensitive adhesive layer A / polarizing plate 1 / pressure-sensitive adhesive layer B / release-agent-attached PET film." In the notation of the above layer configuration and the following layer configuration, " / " indicates that the layers before and after " / " are in direct contact. The film laminated on the side opposite the polarizer of Film F1, which is the first protective film of Polarizing Plate 1, corresponds to the ammonia gas blocking layer. In other words, Film F3 corresponds to the ammonia gas blocking layer. A laminate obtained by peeling and removing the PET film with a release agent from the above Optical Laminate 1 and the following Optical Laminates 2 to 6 corresponds to a composite polarizing plate.

[0089] (Example 2: Preparation of optical laminate 2) Optical laminate 2 was produced in the same manner as above, except that film F3 of optical laminate 1 produced above was replaced with film F4 and the lamination surface of film F4 was subjected to corona treatment. In optical laminate 2, film F4 was an ammonia gas blocking layer.

[0090] (Example 3: Preparation of optical laminate 3) Optical laminate 3 was produced in the same manner as above, except that film F3 of optical laminate 1 produced above was replaced with film F1, and the surface of film F1 not having a hard coat layer laminated thereon was used as the surface to be attached to pressure-sensitive adhesive layer A. In optical laminate 3, film F1 was an ammonia gas blocking layer.

[0091] (Example 4: Preparation of optical laminate 4) Optical laminate 4 was produced in the same manner as in the above-produced optical laminate 1, except that polarizing plate 1 was replaced with polarizing plate 2. In optical laminate 4, film F3 was an ammonia gas blocking layer.

[0092] (Preparation of laminated product of film F4) Two sheets of the above film F4 were laminated together via the adhesive sheet A to prepare a two-sheet laminate (film F4*2). Three sheets of the above film F4 were laminated together via the adhesive sheet A to prepare a three-sheet laminate (film F4*3). When laminating the films F4 together with the adhesive sheet A, corona treatment was performed on the surface of film F4 that was to be laminated with the adhesive sheet A. The two-sheet laminate (film F4*2) had a moisture permeability of 5 g / (m 2 24 hours), the ammonia gas permeation concentration was 100 ppm. For the three-layer laminate (Film F4*3), the moisture permeability was 3 g / (m 2 24 hours), the ammonia gas permeation concentration was 40 ppm.

[0093] (Example 5: Preparation of Optical Laminate 5) Optical laminate 5 was produced in the same manner as above, except that film F3 of optical laminate 1 produced above was replaced with a two-layer laminate (film F4*2) and a corona treatment was performed on the bonding surface of the two-layer laminate (film F4*2) with polarizing plate 1. In optical laminate 5, the multilayered two-layer laminate (film F4*2) is an ammonia gas blocking layer.

[0094] (Example 6: Preparation of optical laminate 6) Optical laminate 6 was produced in the same manner as above, except that Film F3 of the optical laminate 1 produced above was replaced with a three-layer laminate (Film F4*3) and a corona treatment was performed on the bonding surface of the three-layer laminate (Film F4*3) to the polarizing plate 1. In optical laminate 6, the multilayered three-layer laminate (Film F4*3) serves as an ammonia gas blocking layer.

[0095] (Comparative Example 1: Preparation of Optical Laminate 7) One of the release agent-attached PET films in the pressure-sensitive adhesive sheet B was peeled off to expose the pressure-sensitive adhesive layer B, which was then attached to the film F2 of the polarizing plate 1 prepared above, thereby producing an optical laminate 7 in which the pressure-sensitive adhesive layer B was laminated to the film F2 of the polarizing plate 1. The obtained optical laminate had a layer structure of "polarizing plate 1 / pressure-sensitive adhesive layer B / PET film with release agent."

[0096] <Ammonia gas exposure test> The optical laminate 1 was cut into a size of 40 mm × 35 mm so that the absorption axis was parallel to the long side. Next, the PET film with release agent was peeled off, and a 50 mm × 40 mm alkali-free glass ("EAGLE XG" manufactured by Corning) was attached to the surface of the adhesive layer B to obtain a laminate (1) with a glass plate for evaluation. The obtained laminate (1) with a glass plate for evaluation had a layer structure of "Film F3 (acrylic resin film) / adhesive layer A / polarizing plate 1 / adhesive layer B / glass plate." Laminates (2) to (7) with a glass plate for evaluation were obtained in the same manner as above, except that optical laminates 2 to 7 were used instead of the optical laminate 1.

[0097] The laminates (1) to (7) with glass plates were subjected to a temperature of 50°C and a pressure of 5 kgf / cm. 2 (490.3 kPa) for 15 minutes to prepare evaluation samples (A1) to (A7).

[0098] The cross transmittance of the evaluation samples (A1) to (A7) was measured at a wavelength of 700 nm using a spectrophotometer with an integrating sphere (manufactured by JASCO Corporation, V-7100). All of the cross transmittances were 0.01% or less.

[0099] Next, each evaluation sample and 0.07 ml of 10% aqueous ammonia solution were placed in a 500 ml sealed plastic bottle and placed in a 60°C environment for 120 hours. The evaluation sample was removed and the cross transmittance was measured using a spectrophotometer with an integrating sphere (JASCO Corporation, V-7100). The results are shown in Table 2. The ammonia concentration in the sealed plastic bottle in this test was 20,000 ppm.

[0100] [Table 2]

[0101] As shown in Table 2, it was confirmed that the lower the ammonia gas permeation concentration of the blocking layer, the more suppressed the increase in cross transmittance at a wavelength of 700 nm after the evaluation sample was exposed to ammonia gas. In other words, it was confirmed that the easier it is for ammonia gas to penetrate, the more likely red discoloration occurs.

[0102] <High temperature durability test> (Manufacture of pseudo image display device with front panel (1)) The optical laminate 1 obtained in Example 1 was cut into a size of 90 mm × 100 mm so that the absorption axis was parallel to the long side. Next, the PET film with the release agent was peeled off, and a 100 mm × 100 mm alkali-free glass ("EAGLE XG" manufactured by Corning) was attached to the surface of the pressure-sensitive adhesive layer B to obtain a laminate (1) with a glass plate.

[0103] Next, a 100 mm x 100 mm alkali-free glass ("EAGLE XG" manufactured by Corning) was laminated to the surface of the glass plate-attached laminate (1) on which the glass plate was not laminated, via a 250 μm thick adhesive layer, and the laminate was then heated at a temperature of 50°C and a pressure of 5 kgf / cm. 2 (490.3 kPa) for 15 minutes to produce a pseudo-image display device (1) with a front plate. The resulting pseudo-image display device (1) with a front plate had a layer structure of "glass plate / adhesive layer / film F3 (acrylic resin film) / adhesive layer A / polarizing plate 1 / adhesive layer B / glass plate."

[0104] The pseudo image display device means a laminate for high temperature durability testing that simulates an image display device, with the image display panel of the image display device replaced with a glass plate. (Manufacture of pseudo image display devices with front panels (2) to (7)) Pseudo image display devices (2) to (7) with a front plate were produced in the same manner as in the pseudo image display device (1) with a front plate, except that the optical laminate 1 was replaced with the optical laminates 2 to 7.

[0105] (Preparation of sample for cross transmittance measurement) Using a pressure-sensitive adhesive sheet with PET films with release agents on both sides of the pressure-sensitive adhesive layer, one of the PET films with release agents was peeled off to expose the pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer was then attached to Film F2 of the polarizing plate 1 prepared above to produce Laminate R, which was used to measure the crossed transmittance of the evaluation sample. The resulting Laminate R had a layer structure of "polarizing plate 1 / pressure-sensitive adhesive layer / PET film with release agent."

[0106] The obtained laminate R was cut into a size of 90 mm x 100 mm so that the absorption axis was parallel to the short side, to prepare a sample for measuring cross transmittance. [Evaluation of initial optical properties] The pseudo image display devices (1) to (7) with front panels obtained above were measured for their single transmittance using a spectrophotometer and colorimeter (Konica Minolta, Inc., "CM-3700A"). The obtained single transmittances were subjected to luminosity correction using a 2-degree visual field (illuminant C) in accordance with JIS Z 8701:1999 "Methods of displaying color - XYZ color system and X10Y10Z10 color system" to determine the luminosity-corrected single transmittance.

[0107] The release-agent-attached PET film of the laminate R was peeled off and removed to expose the adhesive layer. The adhesive layer of the laminate R was attached to a glass plate on the side of the pseudo image display device (1) with a front panel, which was laminated with adhesive layer B interposed between it and film F2, to obtain an evaluation sample (B1). The pseudo image display device (1) and the laminate R were attached so that the polarizer of the sample for measuring crossed transmittance was in a crossed Nicol position relative to the polarizer of the pseudo image display device (1). The evaluation sample (B1) had a layer structure of "glass plate / adhesive layer / film F3 (acrylic resin film) / adhesive layer A / polarizing plate 1 / adhesive layer B / glass plate / adhesive layer / polarizing plate 1."

[0108] Moreover, evaluation samples (B2) to (B7) were obtained in the same manner as evaluation sample (B1), except that the pseudo image display device (1) with a front panel was replaced with pseudo image display devices (2) to (7). The cross transmittance at a wavelength of 700 nm of the evaluation samples (B1) to (B7) was measured using a spectrophotometer / colorimeter (Konica Minolta, Inc. "CM-3700A") The cross transmittance was 0.01% or less for all samples.

[0109] [High temperature durability evaluation] After the initial optical property evaluation, each evaluation sample was left standing for 670 hours in an environment at a temperature of 105° C. After standing, the luminous efficiency-corrected single transmittance and the crossed transmittance at a wavelength of 700 nm were measured for each evaluation sample in the same manner as above.

[0110] Each evaluation sample was left standing in an environment at a temperature of 105°C for 670 hours, and the difference in luminous efficiency-corrected single transmittance between the initial value and the initial value was used to evaluate it into one of three levels according to the following criteria. Ratings A and B indicate that the change in luminous efficiency-corrected single transmittance is at an acceptable level. A: Visibility correction single unit transmittance change is less than 2.0% B: Visibility correction single unit transmittance change is 2.0% or more and less than 3.0% C: Visibility correction single unit transmittance change is 3.0% or more Table 3 shows the results of the three-level evaluation of the change in luminous efficiency corrected single unit transmittance and the results of the cross transmittance at a wavelength of 700 nm after the high-temperature durability test.

[0111] [Table 3]

[0112] As shown in Table 3, the changes in luminous efficiency-corrected single transmittance were all within the acceptable level, and it was confirmed that polyenization was also suppressed. In particular, in Examples 1 to 3, 5, and 6, in which adhesive composition 1 containing urea was used to bond the polarizer and the protective film, the changes in luminous efficiency-corrected single transmittance were smaller than in Example 4, in which adhesive composition 2 containing no urea was used.

[0113] As shown in Table 3, in evaluation sample (B7) using optical laminate 7 (polarizing plate) of Comparative Example 1, the cross transmittance at a wavelength of 700 nm increased to 1.50 after the high-temperature durability test. In contrast, in evaluation samples (B1) to (B6) using the composite polarizing plates of Examples 1 to 6, the cross transmittance at a wavelength of 700 nm after the high-temperature durability test was 0.13, 0.80, 1.00, 0.13, 0.78, and 0.79, respectively. From these results, it was confirmed that in all of Examples 1 to 6, the increase in the cross transmittance at a wavelength of 700 nm in a high-temperature environment was suppressed compared to Comparative Example 1. It was also found that the increase in the cross transmittance at a wavelength of 700 nm after the high-temperature durability test tended to be suppressed as the ammonia gas permeation concentration of the blocking layer decreased, regardless of the moisture permeability value. [Explanation of symbols]

[0114] 10...Composite polarizing plate 20...Image display device 30...Polarizing plate 31...Polarizer 32...Laminating layer 33...First protective film 34...Second protective film 41…Adhesive layer 42...Adhesive layer 43…Front lamination layer 50...Ammonia gas blocking layer 60...Image display panel 70...Transparent material

Claims

1. A composite polarizing plate including a polarizer having a polarizer in which a dichroic dye is adsorbed and oriented in a polyvinyl alcohol-based resin film, a first protective film laminated on one surface of the polarizer, and a second protective film laminated on the other surface of the polarizer, an ammonia gas blocking layer having an ammonia gas permeation concentration of 500 ppm or less is further laminated on a surface of the first protective film opposite to the polarizer, a composite polarizing plate further comprising a pressure-sensitive adhesive layer laminated on the surface of the second protective film opposite to the polarizer;

2. 2. The composite polarizing plate according to claim 1, wherein the ammonia gas blocking layer is a layer containing at least one selected from the group consisting of a cyclic olefin resin film and an acrylic resin film.

3. 3. A composite polarizing plate as described in claim 1 or 2, wherein the polarizer and the first protective film, and the polarizer and the second protective film are laminated via an adhesive layer containing at least one urea compound selected from the group consisting of urea, urea derivatives, thiourea, and thiourea derivatives.

4. The moisture permeability of the first protective film in an environment of a temperature of 40°C and a relative humidity of 90% is 200 g / (m ２ 3. The composite polarizing plate according to claim 1, wherein the temperature is 24 hours or less.

5. 3. The composite polarizing plate according to claim 1, wherein the first protective film and the ammonia gas blocking layer are laminated via an adhesive layer having a thickness of 10 [mu]m or less.

6. An image display device in which the composite polarizing plate according to claim 1 or 2 and an image display panel are laminated, The image display device further comprises the image display panel laminated on a surface of the second protective film opposite to the polarizer, with the pressure-sensitive adhesive layer interposed therebetween.

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