Optical stack

Abstract

This invention provides an optical laminate capable of suppressing the yellowing of PVA-based polarizers in high-temperature environments. [Solution] The optical laminate comprises a surface protective film, a first protective layer, a PVA-based polarizer, a second protective layer, an adhesive layer α, and a separator film, in this order. At least one of the surface protective film and the separator film has a moisture-impermeable layer and a moisture-absorbing layer positioned closer to the PVA-based polarizer than the moisture-impermeable layer.

Description

TECHNICAL FIELD

[0001] The present invention relates to an optical layered product. BACKGROUND ART

[0002] Conventionally, in a polarizing plate including a PVA-based polarizer and a pair of protective layers sandwiching the polarizer, it is known to provide a moisture-proof layer from the viewpoint of improving high temperature resistance. PRIOR ART DOCUMENTS PATENT DOCUMENTS

[0003] PATENT DOCUMENT 1 Japanese Unexamined Patent Publication No. 03-148603 SUMMARY OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION

[0004] In some applications, a member such as an image display panel is attached to one surface side of a polarizing plate including a PVA-based polarizer, and a member such as a front panel / touch panel is attached to the other surface side of the polarizing plate. Members such as the image display panel and the front panel / touch panel have low moisture permeability. When the polarizing plate is sandwiched between such members including the image display panel and the front panel / touch panel in a state where the PVA-based polarizer contains a large amount of moisture, it becomes difficult to remove moisture from the PVA-based polarizer thereafter. When the polarizing plate in this laminated state is exposed to a high temperature environment, yellowing of the PVA-based polarizer is likely to occur due to the moisture.

[0005] Therefore, conventionally, after attaching a member such as an image display panel to one surface side of the polarizing plate and before attaching a member such as a front panel / touch panel to the other surface side of the polarizing plate, the polarizing plate has been heat-treated in advance to remove moisture from the optical layered product.

[0006] The present invention has been made in view of the above problems, and aims to provide an optical laminate that can suppress yellowing of PVA-based polarizers in image display devices in high-temperature environments, even when components such as image display cells are attached to one side of the polarizing plate, and then components such as a front plate / touch panel are attached to the other side of the polarizing plate without prior heat treatment of the polarizing plate. [Means for solving the problem]

[0007] [1] An optical laminate comprising a surface protective film, a first protective layer, a PVA-based polarizer, a second protective layer, an adhesive layer α, and a separator film in this order, An optical laminate in which at least one of the surface protective film and the separator film has a moisture-impermeable layer and a moisture-absorbing layer positioned closer to the PVA-based polarizer than the moisture-impermeable layer. [2] The surface protective film has the impermeable layer and the moisture-absorbing layer, The optical laminate according to [1], wherein the second protective layer is a moisture-impermeable layer. [3] The surface protective film has an impermeable layer and a moisture-absorbing layer, The optical laminate according to [1] or [2], wherein the separator film has an impermeable layer. [4] The optical laminate according to [3], wherein the separator film further comprises a moisture-absorbing layer positioned closer to the PVA polarizer than the moisture-impermeable layer. [5] The separator film has the impermeable layer and the moisture-absorbing layer, The optical laminate according to any one of [1] to [4], wherein the first protective layer is a moisture-impermeable layer. [6] The separator film has the impermeable layer and the moisture-absorbing layer, The optical laminate according to any one of [1] to [4], wherein the surface protective film comprises an impermeable layer. [7] The optical laminate according to any one of [1] to [6], wherein at least one selected from the group consisting of the PVA polarizer, the adhesive layer between the first protective layer and the PVA polarizer, the adhesive layer between the second protective layer and the PVA polarizer, and the adhesive layer α comprises at least one selected from the group consisting of urea compounds, amide compounds, and hindered amine compounds. [Effects of the Invention]

[0008] According to the present invention, an optical laminate is provided that can suppress yellowing of PVA-based polarizers in image display devices in high-temperature environments, even when components such as image display cells are attached to one side of the polarizing plate, and then components such as a front plate / touch panel are attached to the other side of the polarizing plate without prior heat treatment of the polarizing plate. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic cross-sectional view of the optical laminate according to the first embodiment. [Figure 2] Figure 2 is a schematic cross-sectional view of the optical laminate according to the second embodiment. [Figure 3] Figure 3 is a schematic cross-sectional view of the optical laminate according to the third embodiment. [Figure 4] Figure 4 is a schematic cross-sectional view of the optical laminate according to the fourth embodiment. [Figure 5] Figure 5 is a schematic cross-sectional view of the optical laminate according to the fifth embodiment. [Modes for carrying out the invention]

[0010] An optical laminate according to one embodiment of the present invention comprises, in this order, a surface protective film, a first protective layer, a PVA-based polarizer, a second protective layer, an adhesive layer, and a separator film. At least one of the surface protective film and the separator film has a moisture-impermeable layer and a moisture-absorbing layer positioned closer to the PVA-based polarizer than the moisture-impermeable layer. Each embodiment of the optical laminate will be described in more detail below with reference to the drawings.

[0011] (First Embodiment) As shown in Figure 1, the optical laminate 1000 according to the first embodiment comprises a surface protective film 100, a first protective layer 220, a PVA-based polarizer 210, a second protective layer 230, an adhesive layer α(500), and a separator film 600 in this order. In this embodiment, the surface protective film 100 has an impermeable layer 150 and a moisture-absorbing layer 140 positioned closer to the PVA-based polarizer 210 than the impermeable layer 150. The first protective layer 220, the PVA-based polarizer 210, and the second protective layer 230 constitute a polarizing plate 200.

[0012] (PVA-based polarizer 210) PVA polarizers are films that selectively transmit direct polarization from natural light in a specific direction. PVA polarizers consist of a polyvinyl alcohol-based resin film in which dichroic dyes are oriented. Examples of dichroic dyes include iodine and dichroic dyes.

[0013] The polyvinyl alcohol-based resin that constitutes the polyvinyl alcohol-based resin film is obtained by saponifying a polyvinyl acetate-based resin. As the polyvinyl acetate-based resin, polyvinyl acetate, which is a homopolymer of vinyl acetate, is used, as well as copolymers of vinyl acetate with other monomers copolymerizable thereto. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acid compounds, olefin compounds, vinyl ether compounds, unsaturated sulfone compounds, and (meth)acrylamide compounds having an ammonium group.

[0014] In this specification, "(meth)acrylic" means either acrylic or methacrylic, and the "(meth)" in words like (meth)acrylate has the same meaning.

[0015] The degree of saponification of polyvinyl alcohol-based resins is typically around 85 mol% to 100 mol%, preferably 99 mol% or higher. Polyvinyl alcohol-based resins may be modified; polyvinyl formal, polyvinyl acetal, etc., modified with aldehydes can also be used. The average degree of polymerization of polyvinyl alcohol-based resins is typically 1000 to 10000, preferably 1500 to 5000. The average degree of polymerization of PVA-based resins can be determined in accordance with JIS K 6726 (1994). If the average degree of polymerization is less than 100, it is difficult to obtain desirable polarization performance, and if it exceeds 10000, film processability may be poor.

[0016] The method for producing a PVA-based polarizer in which a dichroic dye is oriented on a polyvinyl alcohol-based resin film is not particularly limited, but examples include a dyeing step in which the polyvinyl alcohol-based resin film is dyed with a dichroic dye such as iodine or a dichroic dye, a crosslinking step in which the polyvinyl alcohol-based resin film after the dyeing step is treated with a crosslinking solution containing a crosslinking agent (e.g., boric acid), and a stretching step in which the polyvinyl alcohol-based resin film is uniaxially stretched.

[0017] The thickness of a PVA polarizer is usually 1 to 30 μm, preferably 2 to 25 μm, and more preferably 2 to 20 μm.

[0018] (Urea compounds, amide compounds, and hindered amine compounds) PVA polarizers may contain at least one compound selected from urea compounds, amide compounds, and hindered amine compounds. Urea compounds include urea, urea derivatives, thiourea, and thiourea derivatives.

[0019] (Urea or urea derivatives) A urea derivative is a compound having a molecular structure in which a portion of the urea molecule is substituted with substituents. Preferably, a urea derivative is a compound in which at least one of the four hydrogen atoms in the urea molecule is substituted with a substituent. In this case, there are no particular restrictions on the substituent, but it is preferable that the substituent consists of carbon atoms, hydrogen atoms, and oxygen atoms.

[0020] Specific examples of urea derivatives include monosubstituted 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. 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, and 1-acetyl-3-methylurea. Examples of 4-substituted ureas include tetramethylurea, 1,1,3,3-tetraethylurea, 1,1,3,3-tetrabutylurea, and 1,3-dimethoxy-1,3-dimethylurea.

[0021] (Thiourea or thiourea derivatives) A thiourea derivative is a compound having a molecular structure in which a portion of thiourea is substituted by substituents. Preferably, a thiourea derivative is a compound in which at least one of the four hydrogen atoms of the thiourea molecule is substituted by a substituent. In this case, there are no particular restrictions on the substituents, but they are preferably substituents consisting of carbon atoms, hydrogen atoms, and oxygen atoms.

[0022] Specific examples of thiourea derivatives include monosubstituted 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. 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, and N-allyl-N'-(2-hydroxyethyl)thiourea. Examples of 3-substituted ureas include trimethylthiourea, and examples of 4-substituted ureas include tetramethylthiourea and 1,1,3,3-tetraethylthiourea.

[0023] Among the above urea compounds, urea derivatives or thiourea derivatives are preferred, and urea derivatives are more preferred. Among urea derivatives, monosubstituted ureas or disubstituted ureas are preferred, and monosubstituted derivatives are more preferred. Disubstituted ureas include 1,1-substituted ureas and 1,3-substituted ureas, but 1,3-substituted ureas are more preferred. In this specification, urea, urea derivatives, thiourea, and thiourea derivatives are referred to as urea-based compounds. As a method for incorporating a urea-based compound into a PVA-based polarizer, the method described in Japanese Patent Application Publication No. 2020-204641 can be applied. Examples of amide compounds are as follows:

[0024] (Amide compounds) An example of an amide compound is the amide compound represented by the following formula (1). [Chem.]]

[0025] In formula (1), R 1A , R 2A and R 3A each independently represent a hydrogen atom, a hydroxy group, an alkyl group having 1 to 5 carbon atoms, or an alkyl group having 1 to 5 carbon atoms in which one or more hydrogen atoms are substituted with a hydroxy group. From the viewpoint of further suppressing a decrease in transmittance and degree of polarization of a polarizing plate under a high temperature environment, R 1A , R 2A and R 3A are each a hydrogen atom, a hydroxy group, or an alkyl group having 1 to 5 carbon atoms, and the total number of carbon atoms of R 1A , R 2A and R 3A is preferably 1 to 5; more preferably, R 1A , R 2A and R 3A are each a hydrogen atom, a hydroxy group, or an alkyl group having 1 to 3 carbon atoms, and the total number of carbon atoms thereof is 1 to 3. Further, from the viewpoint of further suppressing a decrease in transmittance and degree of polarization of a polarizing plate under a high temperature environment, R 3A is preferably a hydrogen atom; more preferably, R 1A is an alkyl group having 1 to 5 carbon atoms, R 2A is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R 3A is a hydrogen atom; still more preferably, R 1A is an alkyl group having 1 to 3 carbon atoms, R 2A is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R 3A is a hydrogen atom; particularly preferably, R 1A is a methyl group or an ethyl group, R 2A is a hydrogen atom, a methyl group or an ethyl group, and R 3A is a hydrogen atom.

[0026] Specific examples of amide compounds include acetamide, propionamide, butyrate amide, valeramide, caproamide, enanthamide, isobutyrate amide, 2-methylbutyrate amide, isovaleramide, pivalamide, 2-methylvaleramide, 2-ethylvaleramide, 3-methylvaleramide, 2-ethylbutyrate amide, 2,2-dimethylbutyrate amide, glycolamide, lactamide, gluconamide, glyceramide, 2-hydroxypropanamide, 2-hydroxybutyrate amide, 3-hydroxybutyrate amide, γ-hydroxybutyrate amide, mevalonamide, pantoinamide, and the like. Amide compounds can be used individually or in combination of two or more.

[0027] (Hindered amine compounds) Hindered amine compounds are secondary or tertiary amines in which an alkyl group is substituted on the carbon adjacent to the amino group, thereby sterically protecting the amino group. Examples include compounds with the following structure: R 1 R represents an oxy radical, a hydrogen atom, a hydroxyl group, or an alkyl group, hydroxyalkyl group, hydroxyalkoxy group, or alkoxy group having 1 to 30 carbon atoms. 2 From R 5 R independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, n represents 0 or 1, and R 6 R represents any organic group. 6 Examples include hydrogen atoms, hydroxyl groups, carboxyl groups, alkyl groups with 1 to 30 carbon atoms, alkoxy groups, acyloxy groups, aryloxy groups, unsubstituted amino groups, and substituted amino groups (e.g., dialkylamino groups). [ka] R 2 From R 5 From the viewpoint of availability and water solubility, it is preferably an alkyl group having 1 to 6 carbon atoms, and more preferably an alkyl group having 1 to 3 carbon atoms. Examples of hindered amine compounds include the following compounds: [ka] [ka] [ka] [ka]

[0028] (First protective layer 220 and second protective layer 230) The first protective layer 220 and the second protective layer 230 each have the function of protecting the surface of the PVA polarizer 210. The PVA polarizer 210 and the first protective layer 220, and the PVA polarizer 210 and the second protective layer 230, may each be directly laminated to each other. Here, "directly laminated" includes embodiments in which the first protective layer 220 and the second protective layer 230 are laminated to the PVA polarizer 210 by their self-adhesion, and embodiments in which they are laminated via an adhesive layer or tack layer. The first protective layer 220 and the second protective layer 230 may be surface-treated (e.g., corona treatment) to improve adhesion with the PVA polarizer 210, and a thin layer such as a primer layer (also called an easy-adhesion layer) may be formed on them.

[0029] As a protective layer, for example, a resin film with excellent transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, and stretchability can be used. The resin film may also be a thermoplastic resin film. Specific examples of such resins include cellulosic resins such as triacetylcellulose; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyethersulfone resins; polysulfone resins; polycarbonate resins; polyamide resins such as nylon and aromatic polyamides; polyimide resins; polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymers; cyclic polyolefin resins having cyclo and norbornene structures (also called norbornene resins); (meth)acrylic resins such as polymethyl methacrylate; polyarylate resins; polystyrene resins; polyvinyl alcohol resins; and mixtures thereof. Protective films of such materials are readily available on the market. Thermosetting resins or UV-curing resins such as (meth)acrylic, urethane, (meth)acrylic-urethane, epoxy, and silicone resins can also be used. In this specification, (meth)acrylic means either acrylic or methacrylic.

[0030] The thickness of the protective layer is preferably 0.1 μm to 60 μm, more preferably 0.5 μm to 40 μm, and even more preferably 1 μm to 30 μm.

[0031] The protective layer may contain any suitable additives depending on the purpose. Examples of additives include: antioxidants such as hindered phenols, phosphorus, and sulfur; stabilizers such as light stabilizers, UV absorbers, weather stabilizers, and heat stabilizers; reinforcing materials such as glass fibers and carbon fibers; near-infrared absorbers; flame retardants such as tris(dibromopropyl) phosphate, triallyl phosphate, and antimony oxide; antistatic agents such as anionic, cationic, and nonionic surfactants; colorants such as inorganic pigments, organic pigments, and dyes; organic and inorganic fillers; resin modifiers; plasticizers; lubricants; and phase difference reducers. The types, combinations, and amounts of additives included can be appropriately set according to the purpose and desired properties.

[0032] Furthermore, a coating layer (surface treatment layer) can be provided on the outer surface of the protective layer to impart desired surface optical properties or other characteristics. Specific examples of surface treatment layers include hard coat layers, anti-glare layers, anti-reflective layers, anti-static layers, and anti-fouling layers. The method for forming the surface treatment layer is not particularly limited, and known methods can be used. The surface treatment layer may be formed on one side of the protective film or on both sides.

[0033] The second protective layer 230 is preferably an impermeable layer, as described later.

[0034] (An adhesive layer that bonds the PVA-based polarizer to the protective layer.) The PVA polarizer and each protective layer may be laminated with an adhesive layer in between. The adhesive can be any suitable adhesive composition (hereinafter also simply referred to as "adhesive"). Specifically, water-based adhesives, solvent-based adhesives, active energy ray-curing adhesives, etc., can be used as the adhesive, but a water-based adhesive is preferred, and a water-based adhesive containing a polyvinyl alcohol resin and a crosslinking agent is more preferred. When adhesive layers are provided on both sides of the PVA polarizer 210, the same adhesive may be used for both sides, or different adhesives may be used for both sides.

[0035] The thickness of the adhesive applied can be set to any appropriate value. For example, it can be set so that an adhesive layer of the desired thickness is obtained after curing or heating (drying). The thickness of the adhesive layer is preferably 0.01 μm to 7 μm, more preferably 0.01 μm to 5 μm, even more preferably 0.01 μm to 2 μm, and most preferably 0.01 μm to 1 μm.

[0036] (Water-based adhesive) Any suitable water-based adhesive can be used. Among them, water-based adhesives containing polyvinyl alcohol (PVA) resin (PVA adhesives) are preferably used. The water-based adhesive may be prepared by dissolving a PVA resin and at least one selected from the group consisting of urea compounds, amide compounds, and hindered amine compounds in water (e.g., pure water). From the viewpoint of adhesiveness, the average degree of polymerization of the PVA resin contained in the water-based adhesive is preferably about 100 to 5500, and more preferably about 1000 to 4500. From the viewpoint of adhesiveness, the average degree of saponification is preferably about 85 mol% to 100 mol%, and more preferably about 90 mol% to 100 mol%.

[0037] The PVA resin included in the above-mentioned water-based adhesive is preferably one containing acetoacetyl groups, because it exhibits excellent adhesion between the PVA resin layer and the protective film, as well as superior durability. The acetoacetyl group-containing PVA resin can be obtained, for example, by reacting a PVA resin with diketene in any way. The degree of acetoacetyl group modification in the acetoacetyl group-containing PVA resin is typically 0.1 mol% or more, and preferably around 0.1 mol% to 20 mol%.

[0038] The resin concentration of the above-mentioned water-based adhesive is preferably 0.1% to 15% by mass, and more preferably 0.5% to 10% by mass.

[0039] The content of PVA-based resin in the water-based adhesive (the proportion of PVA-based resin in the total amount of resin in the adhesive) is preferably 80% by mass or more, more preferably 90% by mass or more, and may be 100% by mass, based on the total amount of resin in the water-based adhesive.

[0040] (Crosslinking agent, solvent) In addition to the PVA resin described above, the water-soluble PVA-based adhesive that can be preferably used in the present invention may also contain a crosslinking agent as needed. Known crosslinking agents can be used. Examples include water-soluble epoxy compounds, dialdehydes, and isocyanates.

[0041] When the PVA resin is an acetoacetyl group-containing PVA-based resin, the crosslinking agent is preferably one of glyoxal, glyoxylate, or methylolmelamine, preferably glyoxal or glyoxylate, and particularly preferably glyoxal.

[0042] Furthermore, water-soluble PVA adhesives may contain organic solvents. In that case, alcohols are preferred because they are miscible with water, and methanol or ethanol are more preferred among alcohols.

[0043] When the water-based adhesive contains at least one selected from the group consisting of urea-based compounds, amide compounds, and hindered amine compounds, the content of at least one selected from the group consisting of urea-based compounds, amide compounds, and hindered amine compounds is preferably 5 to 90% by mass, more preferably 10 to 80% by mass, and even more preferably 30 to 80% by mass, based on the total solid content of the water-based adhesive.

[0044] (Active energy ray curing adhesive) Any suitable adhesive can be used as an active energy ray curing adhesive, as long as it can be cured by irradiation with active energy rays. Examples of active energy ray curing adhesives include ultraviolet curing adhesives and electron beam curing adhesives. Specific examples of curing types for active energy ray curing adhesives include radical curing, cationic curing, anionic curing, and combinations thereof (for example, a hybrid of radical curing and cationic curing).

[0045] Examples of the active energy ray curing adhesives mentioned above include adhesives containing compounds having radical polymerizable groups such as (meth)acrylate groups and (meth)acrylamide groups (e.g., monomers and / or oligomers) as curing components. Specific examples of the active energy ray curing adhesives and their curing methods are described, for example, in Japanese Patent Application Publication No. 2012-144690.

[0046] At least one of the adhesive layers between the first protective layer 220 and the PVA polarizer 210, and the adhesive layer between the second protective layer 230 and the PVA polarizer 210, may contain at least one selected from the group consisting of urea-based compounds, amide compounds, and hindered amine compounds. Only one of the pair of adhesive layers may contain at least one selected from the group consisting of urea-based compounds, amide compounds, and hindered amine compounds, but it is preferable that both contain at least one selected from the group consisting of urea-based compounds, amide compounds, and hindered amine compounds.

[0047] (Adhesive layer α(500)) The adhesive composition forming the adhesive layer α(500) can be any conventionally known adhesive composition with excellent optical transparency, without any particular limitations. For example, adhesive compositions having a base polymer such as acrylic resin, urethane resin, silicone resin, or polyvinyl ether resin can be used. Alternatively, active energy ray curable adhesive compositions or thermosetting adhesive compositions may also be used. Among these, adhesive compositions using acrylic resin as the base polymer, which have excellent transparency, adhesive strength, re-peelability, weather resistance, and heat resistance, are preferred.

[0048] The adhesive composition may further contain a crosslinking agent, a silane compound, an antistatic agent, and the like.

[0049] [(meth)acrylic resin] The (meth)acrylic resin contained in the adhesive composition is preferably a polymer (hereinafter also referred to as "(meth)acrylic ester polymer") whose main component is a structural unit derived from an alkyl (meth)acrylate ester represented by the following formula (I) (hereinafter also referred to as "structural unit (I)"). (For example, containing 50 parts by mass or more per 100 parts by mass of structural units of the (meth)acrylic resin.

[0050] In this specification, (meth)acrylic resin means either acrylic resin or methacrylic resin, and the "(meth)" in (meth)acrylate, etc., has the same meaning. [ka] [In the formula, R 10 R represents a hydrogen atom or a methyl group. 20 [wherein is an alkyl group having 1 to 20 carbon atoms, and the alkyl group may have a linear, branched, or cyclic structure, and the hydrogen atoms of the alkyl group may be replaced by alkoxy groups having 1 to 10 carbon atoms.]

[0051] Examples of (meth)acrylic acid esters represented by formula (I) include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, i-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n- Examples include octyl (meth)acrylate, i-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n- and i-nonyl (meth)acrylate, n-decyl (meth)acrylate, i-decyl (meth)acrylate, n-dodecyl (meth)acrylate, cyclohexyl (meth)acrylate, isobolonyl (meth)acrylate, stearyl (meth)acrylate, and t-butyl (meth)acrylate. Specific examples of alkoxy group-containing alkyl acrylates include 2-methoxyethyl (meth)acrylate and ethoxymethyl (meth)acrylate. Among these, it is preferable to include n-butyl (meth)acrylate or 2-ethylhexyl (meth)acrylate, and particularly preferable to include n-butyl (meth)acrylate.

[0052] (Meth)acrylic acid ester polymers may contain structural units derived from monomers other than structural unit (I). The structural units derived from other monomers may be one type or two or more types. Other monomers that (meth)acrylic acid ester polymers may contain include monomers having polar functional groups, monomers having aromatic groups, and acrylamide monomers.

[0053] Examples of monomers having polar functional groups include (meth)acrylates having polar functional groups. Examples of polar functional groups include hydroxyl groups, carboxyl groups, substituted amino groups or unsubstituted amino groups substituted with alkyl groups having 1 to 6 carbon atoms, and heterocyclic groups such as epoxy groups. Monomers having polar functional groups may also be carboxyl group-containing monomers such as acrylic acid and maleic acid.

[0054] The content of structural units derived from monomers having polar functional groups in the (meth)acrylic acid ester polymer is preferably 10 parts by mass or less, more preferably 0.5 parts by mass or more and 10 parts by mass or less, even more preferably 0.5 parts by mass or more and 5 parts by mass or less, and particularly preferably 1 part by mass or more and 5 parts by mass or less, per 100 parts by mass of the total structural units of the (meth)acrylic acid ester polymer.

[0055] Examples of monomers containing aromatic groups include (meth)acrylic acid esters that have one (meth)acryloyl group and one or more aromatic rings (e.g., a benzene ring, a naphthalene ring, etc.) in the molecule, and that contain a phenyl group, a phenoxyethyl group, or a benzyl group. By including these structural units, it is possible to suppress the whitening phenomenon of polarizing plates that occurs in high temperature and high humidity environments.

[0056] The content of structural units derived from monomers having aromatic groups in the (meth)acrylic acid polymer is preferably 20 parts by mass or less, more preferably 4 parts by mass or more and 20 parts by mass or less, and even more preferably 4 parts by mass or more and 15 parts by mass or less, per 100 parts by mass of the total structural units of the (meth)acrylic acid polymer.

[0057] Examples of acrylamide monomers include N-(methoxymethyl)acrylamide, N-(ethoxymethyl)acrylamide, N-(propoxymethyl)acrylamide, N-(butoxymethyl)acrylamide, and N-(2-methylpropoxymethyl)acrylamide. By including these structural units, the bleed-out of additives such as antistatic agents, which will be discussed later, can be suppressed.

[0058] Furthermore, structural units derived from monomers other than structural unit (I) may include structural units derived from styrene monomers, structural units derived from vinyl monomers, structural units derived from monomers having multiple (meth)acryloyl groups in the molecule, and so on.

[0059] The weight-average molecular weight (hereinafter also simply referred to as "Mw") of the (meth)acrylic resin (1) is preferably 500,000 to 2,500,000. A weight-average molecular weight of 500,000 or more improves the durability of the adhesive layer in high-temperature, high-humidity environments. A weight-average molecular weight of 2,500,000 or less improves the operability when applying the coating liquid containing the adhesive composition. The molecular weight distribution (Mw / Mn), expressed as the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (hereinafter also simply referred to as "Mn"), is usually 2 to 10. In this specification, "weight-average molecular weight" and "number-average molecular weight" are polystyrene equivalent values ​​measured by gel permeation chromatography (GPC).

[0060] The (meth)acrylic resin, when dissolved in ethyl acetate to form a 20% by mass solution, preferably has a viscosity of 20 Pa·s or less at 25°C, and more preferably between 0.1 and 15 Pa·s. When the viscosity of the (meth)acrylic resin at 25°C is within the above range, it contributes to improved durability and reworkability of the polarizing plate containing the adhesive layer formed by the resin. The viscosity can be measured using a Brookfield viscometer.

[0061] The glass transition temperature (Tg) of (meth)acrylic resins is, for example, -60 to 20°C, preferably -50 to 15°C, more preferably -45 to 10°C, and even more preferably -40 to 0°C. The glass transition temperature can be measured by differential scanning calorimeter (DSC).

[0062] (Meth)acrylic resins may contain two or more (meth)acrylic acid ester polymers. Examples of such (meth)acrylic acid ester polymers include relatively low molecular weight (meth)acrylic acid ester polymers whose main component is structural unit (I) derived from the (meth)acrylic acid ester, and whose weight-average molecular weight is in the range of 50,000 to 300,000.

[0063] (Meth)acrylic resins can usually be produced by known polymerization methods such as solution polymerization, bulk polymerization, suspension polymerization, and emulsion polymerization. In the production of (meth)acrylic resins, polymerization is usually carried out in the presence of a polymerization initiator. The amount of polymerization initiator used is usually 0.001 to 5 parts by mass per 100 parts by mass of the total amount of all monomers constituting the (meth)acrylic resin. (Meth)acrylic resins can also be produced by polymerization using active energy rays such as ultraviolet light.

[0064] [Crosslinking agent] The adhesive composition preferably contains a crosslinking agent. Examples of crosslinking agents include conventional crosslinking agents (e.g., isocyanate compounds, epoxy compounds, aziridine compounds, metal chelate compounds, peroxides, etc.), and isocyanate compounds are particularly preferred from the viewpoint of the pot life of the adhesive composition, the crosslinking rate, and the durability of the polarizing plate.

[0065] Isocyanate compounds are compounds having at least two isocyanate groups (-NCO) in their molecule. Specifically, examples include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, naphthalene diisocyanate, and triphenylmethane triisocyanate. Adduct compounds obtained by reacting these isocyanate compounds with polyols such as glycerol and trimethylolprone, as well as dimers and trimers of these isocyanate compounds, are also examples. Two or more isocyanate compounds may be combined.

[0066] The proportion of the crosslinking agent is, for example, 0.01 to 10 parts by mass, preferably 0.05 to 5 parts by mass, and more preferably 0.1 to 1 part by mass, per 100 parts by mass of (meth)acrylic resin.

[0067] [Silane compounds] The adhesive composition may further contain a silane compound.

[0068] Examples of silane compounds include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylethoxydimethylsilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane.

[0069] Furthermore, the silane compound may contain oligomers derived from the above-mentioned silane compound.

[0070] The silane compound content in the adhesive composition is typically 0.01 to 10 parts by mass, preferably 0.05 to 5 parts by mass, per 100 parts by mass of (meth)acrylic resin. When the silane compound content is 0.01 parts by mass or more, the adhesion between the adhesive layer and the adherend tends to improve, and when the content is 10 parts by mass or less, the bleed-out of the silane compound from the adhesive layer tends to be suppressed.

[0071] <Antistatic agent> The adhesive composition may further contain an antistatic agent. Known antistatic agents are examples, with ionic antistatic agents being preferred. Examples of cationic components constituting the ionic antistatic agent include organic cations and inorganic cations. Examples of organic cations include pyridinium cations, imidazolium cations, ammonium cations, sulfonium cations, and phosphonium cations. Examples of inorganic cations include alkali metal cations such as lithium cations, potassium cations, sodium cations, and cesium cations, and alkaline earth metal cations such as magnesium cations and calcium cations. The anionic component constituting the ionic antistatic agent may be either an inorganic anion or an organic anion, but an anionic component containing a fluorine atom is preferred due to its superior antistatic performance. An anionic component containing a fluorine atom is the hexafluorophosphate anion (PF6). - ), bis(trifluoromethanesulfonyl)imide anion [(CF3SO2)2N - ], bis(fluorosulfonyl)imide anion [(FSO2)2N - Examples include anions.

[0072] Ionic antistatic agents that are solid at room temperature are preferred because they offer excellent long-term stability of the antistatic performance of the adhesive composition.

[0073] The amount of antistatic agent is, for example, 0.01 to 20 parts by mass, preferably 0.1 to 10 parts by mass, and more preferably 1 to 7 parts by mass, per 100 parts by mass of (meth)acrylic resin.

[0074] The adhesive composition may contain one or more additives such as UV absorbers, solvents, crosslinking catalysts, tackifiers, and plasticizers. It is also useful to incorporate UV-curable compounds into the adhesive composition, form an adhesive layer, and then cure it by irradiating it with UV light to create a harder adhesive layer.

[0075] The adhesive layer α(500) can be formed, for example, by dissolving or dispersing the adhesive composition in a solvent to obtain a solvent-containing adhesive composition, and then applying this to the surface of the layer on which the adhesive layer is to be provided, and drying it.

[0076] The thickness of the adhesive layer α(500) is typically 0.1 to 30 μm, preferably 3 to 30 μm, and more preferably 5 to 25 μm.

[0077] The adhesive layer α(500) may contain at least one selected from the group consisting of the urea-based compounds, amide compounds, and hindered amine compounds described above.

[0078] Preferably, the peeling force between the adhesive layer α and the second protective layer 230 is greater than the peeling force between the surface protective film 100 and the first protective layer, and the peeling force between the surface protective film 100 and the first protective layer is greater than the peeling force between the adhesive layer α and the separator film 600. The peel force between the adhesive layer α and the separator film 600 may be 0.02 N / 25 mm or more, and may be 0.1 N / 25 mm or less. In this specification, peel force is defined in accordance with the "180-degree peel test method" of JIS Z0237:2009 (Test methods for adhesive tapes and adhesive sheets).

[0079] The peeling force between the adhesive layer α and the second protective layer 230 may be 0.5 N / 25 mm or more.

[0080] (Surface protective film 100) In this embodiment, the surface protection film 100 has, in order from the PVA polarizer 210 side, an adhesive layer 110, a base layer 120, an adhesive layer 130, a moisture-absorbing layer 140, a moisture-impermeable layer 150, and a base layer 160. The surface protection film 100 can protect the surface of the polarizer 200 on the first protective layer 220 side, and can be peeled off from the first protective layer 220 together with the adhesive layer 110 as needed.

[0081] (Base layers 120 and 160) The base layers 120 and 160 function as base materials that support the surface protective film 100. The base layers 120 and 160 may be thermoplastic resin films, and examples include polyolefin resins such as polyethylene resins and polypropylene resins; cyclic polyolefin resins; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polycarbonate resins; (meth)acrylic resins, etc. Of these, polyester resins such as polyethylene terephthalate are preferred. Each base layer may have a single-layer structure, or it may have a multilayer structure of two or more layers. The resin film for the protective film may be a film that has undergone stretching treatment such as uniaxial stretching or biaxial stretching.

[0082] The thickness of the base layers 160 and 120 can be, for example, 30 to 200 μm, preferably 30 to 150 μm, and more preferably 30 to 120 μm.

[0083] It is not essential to have both the base layer 120 and the base layer 160; for example, only one of them may be present, and if at least one of the impermeable layer 150 and the moisture-absorbing layer 140 has sufficient strength to function as a base layer, then neither the base layer 120 nor the base layer 160 may be present.

[0084] (Adhesive layer 110 and adhesive layer 130) The adhesive layer 110 is for fixing the base layer 120 to the first protective layer 220. The adhesive layer 130 is for fixing the moisture-absorbing layer 140 to the base layer 120. The adhesive layers 110 and 130 can be those exemplified in adhesive layer α(500).

[0085] From the viewpoint of suitably peeling the surface protective film 100 from the polarizing plate 200, the peeling force between the adhesive layer 110 and the first protective layer 220 may be 0.05 N / 25 mm or more, and may be 0.2 N / 25 mm or less.

[0086] If the base layer 120 is not present, the adhesive layer 130 is unnecessary.

[0087] The thickness of the adhesive layers 110 and 130 is preferably 5 μm or more, may be 10 μm or more, may be 15 μm or more, and is preferably 30 μm or less, may be 25 μm or less, or may be 20 μm or less.

[0088] (Impermeable layer 150) The moisture-impermeable layer 150 is a layer that sufficiently prevents moisture from permeating. In this specification, the moisture-impermeable layer is defined as a layer with a moisture permeability A of 1.5 g / m², measured at 40°C and 90% relative humidity using the dry-wet sensor method (so-called Lyssy method) in accordance with JIS K7129-1:2019. 2 This refers to layers that are less than or equal to / day. The moisture permeability A of the impermeable layer 150 is 1.5 g / m 2 It may be less than or equal to / day, and 0.3g / m 2 It may be less than or equal to / day, and 0.2g / m 2 It can be less than / day. The moisture permeability B of the impermeable layer 150 was measured at 40°C and 90% relative humidity using the differential pressure sensor method (JIS K 7129-5:2016) and was 5.0 × 10⁻⁶. -4 g / m 2 It can be less than / day.

[0089] Examples of layers that exhibit this type of moisture permeability include cycloolefin polymer films and aluminum layers (e.g., aluminum foil or aluminum vapor-deposited films).

[0090] The thickness of the impermeable layer 150 has a moisture permeability of 1.5 g / m². 2 It can be set appropriately within the range that satisfies the condition of / day or less. Specifically, it may be 10 to 100 μm for cycloolefin polymer film and 5 to 100 μm for aluminum foil.

[0091] (Moisture-absorbing layer 140) The moisture-absorbing layer is a layer that can absorb a sufficient amount of water. In this specification, the amount of water absorbed when stored for 14 days in an environment of 23°C and 55% relative humidity is 0.3 g / m². 2 The layer that meets the above criteria is called the moisture-absorbing layer. The water absorption capacity of the moisture-absorbing layer is 1.0 g / m². 2 It may be greater than or equal to 3.0 g / m 2 That's all.

[0092] The material used to constitute the moisture-absorbing layer can be a water-adsorbing resin or a composition containing a desiccant. Suitable water-adsorbing resins include polyvinylpyrrolidone resins, polyacrylic acid, sodium polyacrylate, polyvinylamine, sodium polyglutamate, polyvinyl alcohol resins, and cellulose derivatives. As desiccants, chemical desiccants such as metal halides, metal oxides, and sulfates, or physical desiccants such as hydrophilic zeolites and silica gel can be used. Desiccants may be used individually or in combination.

[0093] The composition containing the desiccant may, for example, be a composition containing the desiccant and a resin, and the desiccant may be dispersed in the resin. Examples of resins that can be used for dispersion include polyolefin resins, polyester resins, polyamide resins, and vinyl polymers.

[0094] Examples of polyolefin resins include polyethylene resins and polypropylene resins.

[0095] Examples of metal oxides include calcium oxide and aluminum oxide. Examples of metal halides include calcium chloride. Examples of sulfates include magnesium sulfate.

[0096] As hydrophilic zeolite, for example, type A, type X, or type LSX zeolite can be used.

[0097] From the viewpoint of ensuring good moisture absorption capacity, the content of the desiccant is preferably 1% by mass or more relative to the total mass of the moisture-absorbing layer.

[0098] <Method for creating a moisture-absorbing layer> The method for producing the moisture-absorbing layer is not particularly limited, and known or conventional methods can be applied. For example, it can be done by wet lamination, dry lamination, solvent-free dry lamination, extrusion lamination, T-die co-extrusion molding, co-extrusion lamination, inflation, or any other method. For example, a moisture-absorbing film can be obtained by melt-kneading 80 parts by mass of polyethylene resin and 20 parts by mass of calcium oxide.

[0099] At least one of the base layer 120, base layer 160, adhesive layer 110, and adhesive layer 130 of the surface protective film 100 may contain an antistatic agent. Furthermore, an antistatic layer containing an antistatic agent may be provided on the side of the base layer 120 opposite to the side on which the adhesive layer 110 is laminated, or on the side of the base layer 160 opposite to the side on which the moisture-impermeable layer 150 is provided. Examples of antistatic agents include ionic compounds, ionic polymers, conductive polymers, conductive fine particles, surfactants, hydrolyzable organosilicon compounds, and their condensates. Ionic compounds are compounds having an inorganic cation or organic cation and an inorganic anion or organic anion. Examples of ionic polymers include polymers containing ammonium salts or sodium sulfonate. Examples of conductive polymers include polyacetylene, polyphenylene, and polystyrene sulfonic acid. Two or more ionic compounds from the above antistatic agents may be used.

[0100] (Separate film 600) The separator film 600 has a base layer 610. The separator film 600 can protect the surface of the adhesive layer α(500) and can be peeled off from the adhesive layer α(500) as needed.

[0101] (Base material layer 610) The base layer 610 is a layer that supports the separator film 600. The base layer 610 can be one of those listed in base layers 120 and 160. The thickness of the base layer 610 can be, for example, 30 to 200 μm, preferably 30 to 150 μm, and more preferably 30 to 120 μm. The surface of the base layer 610 that contacts the adhesive layer α may be subjected to a known release treatment.

[0102] The base layer 610 of the separator film 600 may contain an antistatic agent. Furthermore, an antistatic layer containing an antistatic agent may be provided on the side of the base layer 610 opposite to the adhesive layer α(500). Examples of antistatic agents include ionic compounds, ionic polymers, conductive polymers, conductive fine particles, surfactants, hydrolyzable organosilicon compounds, and their condensates. Ionic compounds are compounds having an inorganic cation or organic cation and an inorganic anion or organic anion. Examples of ionic polymers include polymers containing ammonium salts or sodium sulfonate. Examples of conductive polymers include polyacetylene, polyphenylene, and polystyrene sulfonic acid. Two or more ionic compounds from the above antistatic agents may be used.

[0103] The optical laminate preferably includes at least one selected from the group consisting of a PVA-based polarizer 210, an adhesive layer between the first protective layer 220 and the PVA-based polarizer 210 (not shown), an adhesive layer between the second protective layer and the PVA-based polarizer (not shown), and an adhesive layer α(500), which includes at least one selected from the group consisting of urea-based compounds, amide compounds, and hindered amine compounds. Multiple of these may include at least one selected from the group consisting of urea-based compounds, amide compounds, and hindered amine compounds. The urea-based compounds, amide compounds, and hindered amine compounds are as described in the section on PVA-based polarizers.

[0104] When the optical laminate contains at least one selected from the group consisting of urea-based compounds, amide compounds, and hindered amine compounds, the content of at least one selected from the group consisting of urea-based compounds, amide compounds, and hindered amine compounds is preferably 0.001 to 0.2% by mass, more preferably 0.003 to 0.2% by mass, and even more preferably 0.007 to 0.2% by mass, based on the solid content of the optical laminate.

[0105] (Second embodiment) Next, with reference to Figure 2, the optical laminate according to the second embodiment will be described. From this point onward, redundant descriptions will be omitted, and only the differences will be explained. The difference between this embodiment and the first embodiment is that the separator film 600 has, in order from the PVA polarizer side, an adhesive layer 620, a moisture-impermeable layer 640, and a substrate layer 650 on the opposite side of the adhesive layer α(500) of the base layer 610. In other words, the second embodiment is a configuration in which the surface protective film 100 has a moisture-impermeable layer and a moisture-absorbing layer, and the separator film 600 has a moisture-impermeable layer. Note that the first protective layer 220 or the second protective layer 230 may or may not be a moisture-impermeable layer.

[0106] The adhesive layer 620 is the same as the adhesive layer 130 described above. The impermeable layer 640 is the same as the impermeable layer 150 described above. The base layer 650 is the same as the base layer 160 described above.

[0107] The base layer 650 is optional. Furthermore, if the impermeable layer 640 or the base layer 650 has sufficient strength, the base layer 610 is not required, and in this case, the adhesive layer 620 is unnecessary.

[0108] (Third embodiment) Next, with reference to Figure 3, the optical laminate according to the third embodiment will be described. The difference between this embodiment and the second embodiment is that the separator film 600 has a moisture-absorbing layer 630 between the adhesive layer 620 and the moisture-impermeable layer 640. The moisture-absorbing layer 630 is positioned closer to the PVA polarizer 210 than the moisture-impermeable layer 640. The moisture-absorbing layer 630 is the same as the moisture-absorbing layer 140 described above. In other words, the third embodiment is a configuration in which both the surface protection film 100 and the separator film 600 have a moisture-impermeable layer and a moisture-absorbing layer.

[0109] (Fourth embodiment) Next, with reference to Figure 4, the optical laminate according to the fourth embodiment will be described. The optical laminate 1000 according to the fourth embodiment differs from the first embodiment in that the surface protective film 100 does not have an adhesive layer 130, a moisture-absorbing layer 140, a moisture-impermeable layer 150, and a base layer 160, and the separator film 600 has an adhesive layer 620, a moisture-absorbing layer 630, a moisture-impermeable layer 640, and a base layer 650 on the side of the base layer 610 opposite the PVA polarizer 210, in order from the PVA polarizer 210 side. In other words, the fourth embodiment is a configuration in which the surface protective film 100 does not have a moisture-absorbing layer and a moisture-impermeable layer, and the separator film 600 has a moisture-impermeable layer and a moisture-absorbing layer.

[0110] The adhesive layer 620 is the same as the adhesive layer 130 of the first embodiment, the moisture-absorbing layer 630 is the same as the moisture-absorbing layer 140 of the first embodiment, the moisture-impermeable layer 640 is the same as the moisture-impermeable layer 150 of the first embodiment, and the base layer 650 is the same as the base layer 160 of the first embodiment.

[0111] It is not essential to have both the base layer 610 and the base layer 650; for example, only one of them may be present, and if at least one of the impermeable layer 640 and the moisture-absorbing layer 630 has sufficient strength to function as a base layer, then neither the base layer 610 nor the base layer 650 may be present. If the base layer 610 is not present, the adhesive layer 620 is unnecessary. In this embodiment, the first protective layer 220 is preferably an impermeable layer.

[0112] (Fifth embodiment) Next, with reference to Figure 5, the optical laminate according to the fifth embodiment will be described. The optical laminate 1000 according to the fifth embodiment differs from that of the fourth embodiment in that the surface protective film 100 has an adhesive layer 130, a moisture-impermeable layer 150, and a base layer 160 on the side of the base layer 120 opposite to the PVA-based polarizer 210, in that order from the PVA-based polarizer 210 side. In other words, the fifth embodiment is a configuration in which the surface protective film 100 has a moisture-impermeable layer, and the separator film 600 has a moisture-impermeable layer and a moisture-absorbing layer.

[0113] It is not essential to have both the base layer 120 and the base layer 160; for example, only one of them may be present, and if the impermeable layer 150 has sufficient strength to function as a base layer, it is not necessary to have both the base layer 120 and the base layer 160. If the base layer 120 is not present, the adhesive layer 130 is unnecessary.

[0114] (How to use optical laminates) Next, an example of a method for manufacturing an image display device using the optical laminate 1000 will be described. First, the separator film 600 is peeled off from the optical laminate 1000, and the laminate of the surface protective film 100 and the polarizing plate 200 is attached to the image display cell via the adhesive layer α. Next, the surface protective film 100 is peeled off the polarizing plate 200. Then, the front plate or touch panel is attached to the peeled surface of the polarizing plate via an adhesive layer or the like. This allows for the creation of an image display device with a layered structure consisting of an image display cell, a polarizing plate, and a front panel or touch panel. Furthermore, heat treatment of the polarizing plate is not required between the time one side of the polarizing plate is attached to the image display cell and the time the front panel or touch panel is attached to the other side of the polarizing plate.

[0115] (Effects and Benefits) According to the optical laminate of this embodiment, yellowing of PVA-based polarizers in high-temperature environments can be suppressed in image display devices with layered structures such as image display cells / polarizing plates / front plates or touch panels. The reason for this is not clear, but the following mechanism of action is considered. In the above-described embodiment, at least one of the surface protective film 100 and the separator film 600 has a combination of an impermeable layer 150 and a moisture-absorbing layer 140 positioned closer to the PVA polarizer 210 than the impermeable layer 150, or a combination of an impermeable layer 640 and a moisture-absorbing layer 630 positioned closer to the PVA polarizer 210 than the impermeable layer 640. Therefore, the movement of moisture from the outside of the optical laminate to the moisture-absorbing layer can be suppressed by the impermeable layer, while moisture inside the PVA polarizer can be absorbed by the moisture-absorbing layer, thereby reducing the amount of moisture inside the PVA polarizer. Therefore, it is considered that an image display device can be obtained by laminating an image display panel, a polarizing plate, and a front plate / touch panel while reducing the amount of moisture inside the PVA polarizer. As a result, this image display device will experience less yellowing of the PVA polarizer even when exposed to high-temperature environments. Furthermore, it is thought that when moisture is present in PVA-based polarizers, the decomposition of the iodine complex is accelerated in high-temperature environments, and polyene formation occurs with the freed iodine acting as a catalyst, resulting in yellowing.

[0116] When only one of the surface protective film 100 and the separator film 600 has an impermeable layer and a moisture-absorbing layer, or when the second protective layer 230 in the first embodiment (Figure 1) is an impermeable layer, or when the first protective layer 220 in the fourth embodiment (Figure 4) is an impermeable layer, if the protective layer on the opposite side of the PVA polarizer 210 from the surface protective film 100 and the separator film 600 is an impermeable layer, the supply of moisture from the opposite side is also suppressed, resulting in an even greater effect.

[0117] Furthermore, if only one of the surface protection film 100 and the separator film 600 has an impermeable layer and a moisture-absorbing layer, the effect is even greater if the other of the surface protection film 100 and the separator film 600 also has an impermeable layer, as in the second embodiment (Figure 2) or the fifth embodiment (Figure 5).

[0118] Furthermore, as shown in the third embodiment (Figure 3), the effect is even greater if both the surface protective film 100 and the separator film 600 have an impermeable layer and a moisture-absorbing layer, respectively.

[0119] Furthermore, the effect is enhanced if at least one selected from the group consisting of a PVA-based polarizer, an adhesive layer between the first protective layer and the PVA-based polarizer, an adhesive layer between the second protective layer and the PVA-based polarizer, and an adhesive layer α contains at least one selected from the group consisting of urea-based compounds, amide compounds, and hindered amine compounds. [Examples]

[0120] (Preparing each film) The following films were prepared. • Laminated film A: A laminated film consisting of PET film (PET1), an impermeable layer (aluminum foil (AL1)), and a moisture-absorbing layer (obtained by cutting "Kyusyukun®" (product name TO-A2) obtained from Maruto Sangyo Co., Ltd.). The moisture permeability A of aluminum foil (AL1) used as an impermeable layer is 0.2 g / m². 2 Less than / day, moisture permeability B is 5.0 × 10 -4 g / m 2 It was less than / day. The water absorption capacity of the moisture-absorbing layer is 6.62 g / m². 2 That was the case.

[0121] • Laminated film B: A laminated film consisting of PET film (PET2) and adhesive layer A. The peeling force between adhesive layer A and the TAC of the polarizing plate was 0.06 N / 25 mm. The moisture permeability A of PET2 film is 15 g / m². 2 It was / day.

[0122] • PET3: A PET film in which one side has been treated with a release agent.

[0123] AL2: Aluminum foil (moisture permeability A is 0.2g / m²) 2Less than / day, moisture permeability B is 5.0 × 10 -4 g / m 2 It was less than / day.

[0124] • COP: Cycloolefin resin film (thickness 51 μm, moisture permeability A is 1.5 g / m²) 2 It was / day.

[0125] • TAC: Triacetylcellulose film (thickness 40 μm)

[0126] • Adhesive layer B: Peeling force from polarizing plate to TAC 15N / 25mm Peel strength with PET3: 0.04 N / 25 mm

[0127] • Adhesive layer C: Acrylic adhesive

[0128] Manufacturing methods for water-based adhesives A-G Z-200 (acetoacetyl-modified PVA manufactured by Mitsubishi Chemical Corporation) was dissolved in pure water to obtain a 5.7 wt% aqueous solution. Pure water, the 5.7 wt% Z-200 aqueous solution, a 40 wt% glyoxal solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and the additives shown in Table 1 were mixed so that the weight ratio of water / Z-200 (solids) / glyoxal (solids) / additives in the adhesive was 100 / 3.0 / 0.15 / X to obtain water-based adhesives A to G. Here, the amount of additives was adjusted so that the mass ratio X was the value shown in Table 1 below. For the obtained water-based adhesives A to G, the concentration of additives per 1 kg of adhesive was determined using the following formula. Additive concentration (mol / kg) = Amount of additive added (kg) / Molecular weight of additive (kg / mol) × 1 / Amount of adhesive prepared (kg) [Table 1]

[0129] Method for manufacturing PVA polarizers A long polyvinyl alcohol film with a thickness of 30 μm (VF-PE#3000 manufactured by Kuraray Co., Ltd.) was continuously transported and immersed in a swelling bath consisting of pure water at 20°C for a residence time of 31 seconds (swelling process). Subsequently, the film removed from the swelling bath was immersed in a 30°C staining bath containing iodine in a potassium iodide / water ratio of 2 / 100 (by weight) for a residence time of 122 seconds (staining process). Next, the film removed from the staining bath was immersed in a 56°C crosslinking bath in a potassium iodide / boric acid / water ratio of 12 / 4.1 / 100 (by weight) for a residence time of 70 seconds, and then immersed in a 40°C crosslinking bath in a potassium iodide / boric acid / water ratio of 9 / 2.9 / 100 (by weight) for a residence time of 13 seconds (crosslinking process). In the dyeing and crosslinking processes, axial stretching in the MD direction was performed by stretching between rolls in the bath. The total stretching ratio relative to the original film was 5.5 times. Next, the film removed from the crosslinking bath was immersed in a washing bath consisting of 5°C pure water for a residence time of 3 seconds (washing process), and then introduced into an 80°C drying oven for a residence time of 190 seconds to dry (drying process) to obtain a polarizer. The thickness of the polarizer obtained in this example was 12 μm.

[0130] Fabrication of polarizing plates A to G Using a roll-type laminator, a 40 μm thick triacetylcellulose film, treated with saponification, was bonded to both sides of a PVA-based polarizer via the aqueous adhesive described in Table 1. The resulting laminate was dried at 80°C for 3 minutes to obtain polarizers A to G. The polarizers were composed of TAC / PVA-based polarizer / TAC.

[0131] Preparation of surface protective film A A surface protective film A was obtained by laminating the moisture-absorbing layer side of laminated film A onto the PET2 side of laminated film B via an adhesive layer C. The surface protection film A consists of laminated film A (PET1 / impermeable layer (AL1) / moisture-absorbing layer) / adhesive layer C / laminated film B (PET2 / adhesive layer A).

[0132] Preparation of surface protective film B A surface protective film B was obtained by laminating COP onto the PET2 surface of laminated film B via an adhesive layer C. The surface protective film B consists of COP / adhesive layer C / laminated film B (PET2 / adhesive layer A).

[0133] Fabrication of surface protective film C A surface protective film C was obtained by laminating AL2 onto the PET2 surface of laminated film B via an adhesive layer C. The surface protective film C consists of AL2 / adhesive layer C / laminated film B (PET2 / adhesive layer A).

[0134] Preparation of Separator Film A • Separator film A was obtained by laminating COP on the side of PET3 opposite to the release treatment surface via an adhesive layer C. The composition of separator film A is PET3 / adhesive layer C / COP.

[0135] Preparation of Separator Film B • Separator film B was obtained by laminating AL2 on the side of PET3 opposite to the release treatment surface via an adhesive layer C. The composition of separator film B is PET3 / adhesive layer C / AL2.

[0136] Fabrication of Separator Film C • Separator film C was obtained by laminating the moisture-absorbing layer side of laminated film A to the opposite side of the release-treated surface of PET3 via an adhesive layer C. The composition of the separator film C is PET3 / adhesive layer C / laminated film A (moisture-absorbing layer / impermeable layer (AL1) / PET1).

[0137] Manufacturing of optical laminates (polarizing plates with moisture-absorbing layers) <Example 1> One TAC surface of polarizing plate A was subjected to corona treatment, and adhesive B and separator film A (PET3 / adhesive layer C / COP) were laminated to the corona-treated surface in that order using a roll laminator. Next, surface protective film A was laminated to the outside of the other TAC of polarizing plate A using a roll-type laminator to obtain an optical laminate (polarizing plate with moisture-absorbing layer). The optical laminate was stored for 14 days under controlled conditions of 23°C and 55% relative humidity. The optical laminate consists of a surface protective film A (PET1 / impermeable layer (AL1) / moisture-absorbing layer / adhesive C / PET2 / adhesive A) / polarizing plate A (TAC / polarizer / TAC) / adhesive layer B / separator film A (PET3 / adhesive layer C / COP).

[0138] <Examples 2-15, Comparative Examples 1-2> An optical laminate was obtained in the same manner as in Example 1, except that the separator film, surface protection film, and polarizing plate were changed to the separator film and surface protection film listed in Table 2. Separator films A to C were laminated so that PET3 was on the polarizing plate side, and the surface protection film was laminated so that adhesive layer A was on the polarizing plate side. The optical laminates of Examples 1 to 2 are the second embodiment in this specification, the optical laminates of Examples 3 to 8 are the fifth embodiment, and the laminates of Examples 9 to 15 are the third embodiment. In Comparative Examples 1 and 2, laminated film B was used as the surface protective film, and PET3 was used as the separator film.

[0139] Preparation of samples for durability evaluation <Examples 1-15 and Comparative Example 1> The obtained optical laminate (polarizing plate with moisture-absorbing layer) was cut to 30 mm in the MD direction (polarizer absorption axis direction) and 30 mm in the TD direction (direction perpendicular to the polarizer absorption axis direction). The separator film was peeled off, and adhesive layer B was bonded to the center of a 40 mm x 40 mm x 0.7 mm thick alkali-free glass. The laminate configuration at this time was surface protective film / polarizing plate / adhesive layer B / alkali-free glass. After leaving this laminate at 23°C and 55% relative humidity for 7 days, the surface protective film was peeled off, and a 30 mm x 30 mm x 0.15 mm thick cover glass was bonded to the surface of the polarizing plate via a 25 μm thick acrylic adhesive to obtain a sample for durability evaluation. The sample for durability evaluation consists of a cover glass, adhesive, polarizer (TAC / polarizer / TAC), adhesive layer B, and alkali-free glass.

[0140] Preparation of samples for durability evaluation <Comparative Example 2> The obtained optical laminate (polarizing plate with moisture-absorbing layer) was cut to 30 mm in the MD direction (polarizer absorption axis direction) and 30 mm in the TD direction (direction perpendicular to the polarizer absorption axis direction). The separator film was peeled off, and adhesive layer B was bonded to the center of a 40 mm x 40 mm x 0.7 mm thick alkali-free glass. The laminate configuration at this time was surface protective film / polarizing plate / adhesive layer B / alkali-free glass. This laminate was heated in a 95°C oven for 3 hours, stored for 24 hours under controlled humidity of 23°C and 55% relative humidity, then the surface protective film was peeled off, and a 30 mm x 30 mm x 0.15 mm thick cover glass was bonded to the surface of the polarizing plate via a 25 μm thick acrylic adhesive to obtain a sample for durability evaluation. The sample for durability evaluation consists of a cover glass, adhesive, polarizer (TAC / polarizer / TAC), adhesive layer B, and alkali-free glass.

[0141] (moisture permeability measurement) (Measurement of moisture permeability A (Lyssy method)) • Detection method: Humidity sensor method (compliant with JIS K7129-1:2019) • Measuring device: Lyssy L80 series water vapor transmission rate Measurement conditions: 40°C, 90% relative humidity ·Measurement area: 5.0×10 -3 m 2 • Lower limit of detection: 0.2 g / m 2 / day ·method: (1) The sample was inserted and fixed between the upper chamber, which had a humidity sensor attached, and the lower chamber (saturated water vapor). (2) The upper chamber was dried to a predetermined level (lower humidity limit). (3) The upper chamber was humidified by the permeation of water vapor from the sample, and the time it took for the humidity in the upper chamber to change from 9.9% to 10.1% was measured, and the transmittance A was calculated using the following formula. FVTR sample (g / m 2 / day)=WVTR std .×T std . / T sample FVTR std .: Water vapor transmission rate (g / m³) of a standard sample 2 / day) T std .: Time it takes for humidity to change from 9.9% to 10.1% in a standard sample. T sample Time taken for the humidity in the test sample to change from 9.9% to 10.1%

[0142] (Measurement of moisture permeability B (Delta Palm)) • Detection method: Differential pressure sensor method (compliant with JIS K 7129-5:2016) ·Model: Standard 1-chamber manual type DP-ST1 CM Measurement conditions: 40°C, 90% relative humidity ·method: (1) The sample was inserted and fixed between the upper chamber, which had a steam supply tank, and the lower chamber, which had a pressure sensor. (2) The constant temperature chamber was set to 40°C, and both the upper and lower chambers were subjected to reduced-pressure drying by vacuum evacuation. (3) With the upper and lower chambers sealed, water vapor at 40°C and 90% relative humidity was introduced from the supply side, and the WVTR was calculated from the pressure change in the lower chamber over time. • Lower limit of measurement: 5.0 × 10 -4 g / m 2 / day

[0143] (Regulations on the amount of water absorbed by the moisture-absorbing layer) The amount of water absorbed by the moisture-absorbing layer was determined by the following method. A 100 x 100 mm moisture-absorbing layer was vacuum-dried at 23°C for 8 hours, and its initial weight was measured. Next, the weight was measured after storage for 2 weeks under controlled conditions of 23°C and 55% relative humidity, and the amount of water absorbed was calculated using the following formula. Water absorption [g / m 2] = (Weight after storage at 23℃ and 55% relative humidity - Initial weight) × 100

[0144] (Measurement of water absorption amount in the moisture-absorbing layer within laminated film A (Moisture-absorbing-kun(R))) A piece of moisture-absorbing film (product name TO-A2) was cut to 100mm x 100mm, vacuum-dried at 23°C for 8 hours, and its weight (initial weight) was measured. Next, this film was stored for 2 weeks in an environment of 23°C and 55% relative humidity, and its weight (weight after storage) was measured. The amount of water absorbed by moisture-absorbing film (Kyussukukun) was calculated using the following formula. Water absorption [g / m 2 ] = (Weight after storage - Initial weight) × 100 The amount of water absorbed by the moisture-absorbing layer of the moisture-absorbing material was calculated by subtracting the amount of water absorbed by the PET film (PET1) and the impermeable layer (AL1), which are layers other than the moisture-absorbing layer within the moisture-absorbing material, from the amount of water absorbed by the moisture-absorbing material obtained from the moisture-absorbing material.

[0145] (Measurement of peeling force) • Peeling force between the surface protective film (adhesive layer A) and the polarizing plate TAC A laminate was prepared consisting of laminated film B (PET film (PET2) / adhesive layer A) / polarizing plate A / adhesive layer (thickness 25 μm). This laminate was cut to a size of 25 mm × 120 mm, the adhesive layer and glass were bonded together, and then autoclaved at a temperature of 50°C and a pressure of 0.49 MPa to obtain test pieces for evaluating peel strength. After storing the test specimens for evaluating peel strength at a temperature of 23°C and a relative humidity of 60% for 24 hours, the PET film and adhesive layer A were peeled from the TAC of polarizing plate A using an Autograph (manufactured by Shimadzu Corporation, product name "AGS-X(50N)") at a peel angle of 180° and a peel speed of 300 mm / min. The test force at which the film was peeled was averaged over the peeled section to obtain the peel strength between the surface protective film (adhesive layer A) and the polarizing plate. • Peeling force between adhesive layer α (adhesive layer B) and the TAC of the polarizing plate Except for preparing a laminate consisting of a PET film (PET3), adhesive layer B, polarizing plate A, and adhesive layer (thickness 25 μm), the PET film and adhesive layer B were peeled from the TAC of polarizing plate A in the same manner as the peeling force between adhesive layer A and the polarizing plate A, and the peeling force between adhesive layer α (adhesive layer B) and the polarizing plate was obtained. • Peeling force between adhesive layer α (adhesive layer B) and separator film (PET3) A PET film (PET3) measuring 25 mm x 120 mm was prepared. After laminating PET3 to glass via adhesive layer B, it was autoclaved at a temperature of 50°C and a pressure of 0.49 MPa to obtain a test specimen for evaluating peel strength. In this test specimen, the release-treated side of PET3 was positioned on the side of adhesive layer B. After storing the test specimens for evaluating peel strength at a temperature of 23°C and a relative humidity of 60% for 24 hours, the PET film was peeled from adhesive layer B using an Autograph (manufactured by Shimadzu Corporation, product name "AGS-X(50N)") at a peel angle of 180° and a peel speed of 300 mm / min. The test force at which the film was peeled was averaged over the peeled section to obtain the peel strength between adhesive layer α (adhesive layer B) and the separator film. The measurement results showed that, in the examples, the peeling force when peeling the surface protective film from the polarizing plate was greater than the peeling force when peeling the separator film from the adhesive layer. Furthermore, the peeling force when peeling the surface protective film from the polarizing plate was less than the peeling force when peeling the polarizing plate from adhesive α.

[0146] (Initial measurement of Ty, Py, and individual b values) For the durability evaluation samples obtained in each example and comparative example, the MD transmittance and TD transmittance in the wavelength range of 380 to 780 nm were measured using a spectrophotometer with an integrating sphere (manufactured by JASCO Corporation, product name: V7100). Subsequently, the single-element transmittance and polarization degree at each wavelength were calculated using the following formula: Single element transmittance (%) = (MD transmittance + TD transmittance) / 2 Polarization degree (%) = {(MD transmittance - TD transmittance) / (MD transmittance + TD transmittance)} × 100 It was calculated based on the following. Here, MD transmittance is the transmittance when the direction of polarization emitted from the Grant-Thomson prism is parallel to the transmission axis of the durability evaluation sample. TD transmittance is the transmittance when the direction of polarization emitted from the Grant-Thomson prism is perpendicular to the transmission axis of the durability evaluation sample. The obtained individual transmittance and polarization degree are referred to JIS Z8701:1999 "Methods of color representation - XYZ color system and X 10 Y 10 Z 10 The luminous efficiency was corrected using a 2-degree field of view (C light source) of the "color system," and the luminous efficiency corrected single transmittance (Ty), luminous efficiency corrected polarization degree (Py), and single b value were determined. These were taken as the initial Ty, Py, and single b values. The results are shown in Table 2.

[0147] (Measurement of Ty and Py after high-temperature durability test) A high-temperature durability test was conducted by storing the durability evaluation sample in a heated environment at 105°C for 500 hours. After the high-temperature durability test, the transmittance and polarization degree of the durability evaluation sample were measured using the same method as described above, and Ty and Py were determined. From the obtained Ty and Py values ​​after the high-temperature durability test, the effect of suppressing the decrease in transmittance and polarization degree under high-temperature conditions was evaluated based on the following criteria. The results are shown in Table 2. The yellowing was judged according to the following criteria. A: Ty > 36% B: 36% ≥ Ty > 28% C: 28% ≥ Ty > 15% D: 15% ≥ Ty > 5% E: Ty ≤ 5%

[0148] [Table 2] [Table 3] [Explanation of symbols]

[0149] 100...Surface protective film, 140, 630...Moisture-absorbing layer, 150, 640...Moisture-impermeable layer, 200...Polarizing plate, 210...PVA-based polarizer, 220...First protective layer, 230...Second protective layer, 500...Adhesive layer α, 600...Separator film, 1000...Optical laminate.

Claims

1. An optical laminate comprising, in this order, a surface protective film, a first protective layer, a PVA-based polarizer, a second protective layer, an adhesive layer α, and a separator film, An optical laminate in which at least one of the surface protective film and the separator film has a moisture-impermeable layer and a moisture-absorbing layer positioned closer to the PVA polarizer than the moisture-impermeable layer.

2. The surface protective film has the impermeable layer and the moisture-absorbing layer, The optical laminate according to claim 1, wherein the second protective layer is a moisture-impermeable layer.

3. The surface protective film has a moisture-impermeable layer and a moisture-absorbing layer, The optical laminate according to claim 1, wherein the separator film has a moisture-impermeable layer.

4. The optical laminate according to claim 3, wherein the separator film further comprises a moisture-absorbing layer positioned closer to the PVA polarizer than the impermeable layer.

5. The separator film has the impermeable layer and the moisture-absorbing layer, The optical laminate according to claim 1, wherein the first protective layer is a moisture-impermeable layer.

6. The separator film has the impermeable layer and the moisture-absorbing layer, The optical laminate according to claim 1, wherein the surface protective film includes a moisture-impermeable layer.

7. The optical laminate according to any one of claims 1 to 6, wherein at least one selected from the group consisting of the PVA polarizer, the adhesive layer between the first protective layer and the PVA polarizer, the adhesive layer between the second protective layer and the PVA polarizer, and the adhesive layer α comprises at least one selected from the group consisting of urea compounds, amide compounds, and hindered amine compounds.

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