Optical laminate

Abstract

Provided is an optical laminate capable of inhibiting yellowing of a PVA-based polarizing plate in a high-temperature environment. The optical laminate has, in order, a surface protective film, a first protective layer, a PVA-based polarizing plate, a second protective layer, an adhesive layer α, and a separator. At least one of the surface protective film and the separator has a moisture-impermeable layer and a moisture-absorbing layer disposed closer to the PVA-based polarizing plate than the moisture-impermeable layer.

Description

Technical Field

[0001] This invention relates to optical laminates. Background Technology

[0002] It has long been known that, from the viewpoint of improving high-temperature resistance, a moisture-proof layer is imparted to a polarizing plate having a PVA-based polarizer and a pair of protective layers holding the PVA-based polarizer.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 03-148603 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] In some applications, an image display panel or similar component is attached to one side of a polarizing plate containing a PVA-based polarizer, while a front panel / touch panel or similar component is attached to the other side. The image display panel and front panel / touch panel have low moisture permeability. If the polarizing plate is sandwiched between such components while the PVA-based polarizer contains a large amount of water, it becomes difficult to remove the moisture from the PVA-based polarizer afterward. Furthermore, if the polarizing plate is exposed to a high-temperature environment in this laminated state, yellowing of the PVA-based polarizer is easily caused by moisture.

[0008] Therefore, in the past, after attaching components such as an image display panel to one side of the polarizing plate and before attaching components such as a front panel / touch panel to the other side of the polarizing plate, the polarizing plate was preheated to remove moisture from the optical laminate.

[0009] The present invention was made in view of the above-mentioned problems, and its object is to provide an optical laminate that can suppress yellowing of PVA polarizers in image display devices under high temperature environments, even after attaching components such as image display units to one side of the polarizer and attaching components such as front panels / touch panels to the other side of the polarizer without performing pre-heat treatment of the polarizer.

[0010] Methods for solving problems

[0011] [1] An optical laminate, comprising sequentially a surface protective film, a first protective layer, a PVA-based polarizer, a second protective layer, an adhesive layer α, and a separator,

[0012] At least one of the aforementioned surface protective film and the aforementioned separator has a moisture-impermeable layer and a moisture-absorbing layer disposed closer to the aforementioned PVA-based polarizer than the aforementioned moisture-impermeable layer.

[0013] [2] According to the optical laminate described in [1], the surface protective film has the aforementioned moisture-impermeable layer and the aforementioned moisture-absorbing layer.

[0014] The aforementioned second protective layer is a moisture-proof layer.

[0015] [3] According to the optical laminate described in [1] or [2], wherein the aforementioned surface protective film has a moisture-impermeable layer and a moisture-absorbing layer,

[0016] The aforementioned diaphragm has a moisture-impermeable layer.

[0017] [4] According to the optical laminate described in [3], the diaphragm further comprises a moisture-absorbing layer, which is disposed closer to the PVA polarizer than the moisture-impermeable layer.

[0018] [5] An optical laminate according to any one of [1] to [4], wherein the diaphragm has the aforementioned impermeable layer and the aforementioned moisture-absorbing layer.

[0019] The first protective layer mentioned above is a moisture-proof layer.

[0020] [6] An optical laminate according to any one of [1] to [4], wherein the diaphragm has the aforementioned impermeable layer and the aforementioned moisture-absorbing layer.

[0021] The aforementioned surface protective film includes a moisture-impermeable layer.

[0022] [7] An optical laminate according to any one of [1] to [6], wherein at least one 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 urea compounds, amide compounds and hindered amine compounds.

[0023] Invention Effects

[0024] According to the present invention, an optical laminate is provided that can suppress yellowing of PVA-based polarizers in image display devices under high-temperature environments, even after attaching components such as image display units to one side of the polarizer and attaching components such as front panels / touch panels to the other side of the polarizer without performing pre-heat treatment of the polarizer. Attached Figure Description

[0025] Figure 1 This is a cross-sectional schematic diagram of the optical laminate of the first embodiment.

[0026] Figure 2 This is a cross-sectional schematic diagram of the optical laminate according to the second embodiment.

[0027] Figure 3This is a cross-sectional schematic diagram of the optical laminate according to the third embodiment.

[0028] Figure 4 This is a cross-sectional schematic diagram of the optical laminate according to the fourth embodiment.

[0029] Figure 5 This is a cross-sectional schematic diagram of the optical laminate according to the fifth embodiment. Detailed Implementation

[0030] An optical laminate according to one embodiment of the present invention comprises, in sequence, a surface protective film, a first protective layer, a PVA-based polarizer, a second protective layer, an adhesive layer, and a separator. At least one of the surface protective film and the separator has a moisture-impermeable layer and a moisture-absorbing layer disposed closer to the PVA-based polarizer than the moisture-impermeable layer.

[0031] Hereinafter, various embodiments of the optical laminate will be described in more detail with reference to the accompanying drawings.

[0032] (First Implementation)

[0033] like Figure 1 As shown, the optical laminate 1000 of the first embodiment sequentially includes 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 600. Furthermore, in this embodiment, the surface protective film 100 has a moisture-impermeable layer 150 and a moisture-absorbing layer 140 disposed closer to the PVA-based polarizer 210 than the moisture-impermeable layer 150. It should be noted that the first protective layer 220, the PVA-based polarizer 210, and the second protective layer 230 constitute a polarizing plate 200.

[0034] (PVA polarizer 210)

[0035] PVA-based polarizers are films that selectively transmit linearly polarized light in a specific direction from natural light. PVA-based polarizers are formed by orienting dichroic pigments within a polyvinyl alcohol-based resin film. Examples of dichroic pigments include iodine and dichroic dyes.

[0036] The polyvinyl alcohol (PVA) resin constituting the polyvinyl alcohol (PVA) resin film is obtained by saponifying a polyvinyl acetate (PVC) resin. Besides PVC as a homopolymer of PVC, copolymers of PVC and other monomers capable of copolymerizing with PVC can also be used as PVC resins. Examples of other monomers capable of copolymerizing with PVC include unsaturated carboxylic acid compounds, olefin compounds, vinyl ether compounds, unsaturated sulfone compounds, and (meth)acrylamide compounds with ammonium groups.

[0037] It should be noted that in this specification, "(meth)acrylic acid" can refer to either acrylic acid or methacrylic acid, and "(meth)" in (meth)acrylates, etc., has the same meaning.

[0038] The degree of saponification of polyvinyl alcohol (PVA) resins is typically between 85 mol% and 100 mol%, preferably 99 mol% or higher. PVA resins can be modified, and aldehyde-modified PVA formal, PVA acetal, etc., can also be used. The average degree of polymerization of PVA resins is typically between 1000 and 10000, preferably between 1500 and 5000. The average degree of polymerization of PVA resins can be determined according to JIS K 6726 (1994). If the average degree of polymerization is less than 100, it is difficult to obtain optimal polarization properties; if it exceeds 10000, the film processability is sometimes poor.

[0039] There is no particular limitation on the manufacturing method of PVA polarizers formed by orienting dichroic pigments on polyvinyl alcohol-based resin films. For example, a manufacturing method can be described by the following steps: a dyeing step of dyeing the polyvinyl alcohol-based resin film with dichroic pigments such as iodine or dichroic dyes; a crosslinking step of treating the dyed polyvinyl alcohol-based resin film with a crosslinking solution containing a crosslinking agent (e.g., boric acid); and a stretching step of uniaxially stretching the polyvinyl alcohol-based resin film.

[0040] The thickness of PVA polarizers is typically 1–30 μm, preferably 2–25 μm, and more preferably 2–20 μm.

[0041] (Urea compounds, amide compounds, and hindered amine compounds)

[0042] PVA-based polarizers may contain at least one compound selected from urea compounds, amide compounds, and hindered amine compounds. Urea compounds refer to urea, urea derivatives, thiourea, and thiourea derivatives.

[0043] (Urea or urea derivatives)

[0044] Urea derivatives are compounds having a molecular structure in which a portion of the urea molecules are substituted with substituents. Preferably, as urea derivatives, compounds in which at least one of the four hydrogen atoms in the urea molecule is substituted with a substituent are preferred. In this case, there are no particular limitations on the substituents, but substituents containing carbon, hydrogen, and oxygen atoms are preferred.

[0045] Specific examples of urea derivatives, as monosubstituted ureas, include 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.

[0046] 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.

[0047] Examples of tetrasubstituted ureas include tetramethylurea, 1,1,3,3-tetraethylurea, 1,1,3,3-tetrabutylurea, and 1,3-dimethoxy-1,3-dimethylurea.

[0048] (Thiourea or thiourea derivatives)

[0049] Thiourea derivatives are compounds having a molecular structure in which a portion of the thiourea molecules are substituted with substituents. Preferably, thiourea derivatives are compounds in which at least one of the four hydrogen atoms of the thiourea molecule is substituted with a substituent.

[0050] In this case, there are no particular restrictions on the substituents, but substituents containing carbon, hydrogen and oxygen atoms are preferred.

[0051] Specific examples of thiourea derivatives, as monosubstituted thioureas, include 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.

[0052] 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.

[0053] Examples of trisubstituted ureas include trimethylthiourea, and examples of tetrasubstituted ureas include tetramethylthiourea and 1,1,3,3-tetraethylthiourea.

[0054] Among the aforementioned urea compounds, urea derivatives or thiourea derivatives are preferred, and urea derivatives are more preferred. Among the 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, and 1,3-substituted ureas are more preferred.

[0055] It should be noted that in this specification, urea, urea derivatives, thiourea, and thiourea derivatives are referred to as urea compounds.

[0056] As a method for containing urea compounds in PVA polarizers, the method described in Japanese Patent Application Publication No. 2020-204641 can be applied.

[0057] Examples of amide compounds are as follows.

[0058] (Amide compounds)

[0059] Examples of amide compounds are those shown in formula (1) below.

[0060] [Chemical Formula 1]

[0061]

[0062] In equation (1), R 1A R 2A and R 3A Each of these elements independently represents a hydrogen atom, a hydroxyl group, an alkyl group with 1 to 5 carbon atoms, or an alkyl group with 1 to 5 carbon atoms in which one or more hydrogen atoms are replaced by a hydroxyl group. From the viewpoint of further suppressing the decrease in transmittance and polarization degree of the polarizer under high-temperature conditions, R... 1A R 2A and R 3A Preferably, it is a hydrogen atom, a hydroxyl group, or an alkyl group having 1 to 5 carbon atoms and R 1A R 2A and R 3A The total number of carbon atoms is 1 to 5, more preferably hydrogen atoms, hydroxyl groups, or alkyl groups having 1 to 3 carbon atoms and R 1A R 2A and R 3A The total number of carbon atoms is 1 to 3. Furthermore, from the viewpoint of further suppressing the decrease in transmittance and polarization degree of the polarizer under high-temperature conditions, R... 3A Preferably, hydrogen atoms, more preferably R 1A Alkyl groups having 1 to 5 carbon atoms, R 2A It is an alkyl group having 1 to 5 carbon atoms, and R 3A For hydrogen atoms, R is further preferred.1A Alkyl groups having 1 to 3 carbon atoms, R 2A It is an alkyl group having 1 to 3 carbon atoms, and R 3A For hydrogen atoms, R is particularly preferred. 1A Methyl or ethyl, R 2A It is a hydrogen atom, a methyl or ethyl atom, and R 3A It is a hydrogen atom.

[0063] Specific examples of amide compounds include acetamide, propionamide, butyramide, valerate amide, hexanoamide, heptaanoamide, isobutyramide, 2-methylbutyramide, isovaleramide, neovalerate amide, 2-methylvalerate amide, 2-ethylvalerate amide, 3-methylvalerate amide, 2-ethylbutyramide, 2,2-dimethylbutyramide, hydroxyacetamide, lactamide, gluconic acid amide, glyceryl amide, 2-hydroxypropionamide, 2-hydroxybutyramide, 3-hydroxybutyramide, γ-hydroxybutyramide, mevalerate amide, pantothenic acid amide, etc. Amide compounds can be used alone or in combination of two or more.

[0064] (Hindered amine compounds)

[0065] Hindered amine compounds are secondary or tertiary amines in which an alkyl group is sterically protected on the carbon adjacent to the amino group. Examples of such compounds include those with the following structures. R 1 R represents an oxygen free 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 ~R 5 Independently representing hydrogen atoms or alkyl groups having 1 to 10 carbon atoms, n represents 0 or 1, 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).

[0066] [Chemical Formula 2]

[0067]

[0068] From the perspective of ease of acquisition and water solubility, R 2 ~R 5 Preferably, it is an alkyl group having 1 to 6 carbon atoms, and more preferably an alkyl group having 1 to 3 carbon atoms.

[0069] An example of a hindered amine compound is the following compound.

[0070] [Chemical Formula 3]

[0071]

[0072] [Chemical Formula 4]

[0073]

[0074] [Chemical Formula 5]

[0075]

[0076] [Chemical Formula 6]

[0077]

[0078] (First protective layer 220 and second protective layer 230)

[0079] The first protective layer 220 and the second protective layer 230 each function to protect the surface of the PVA-based polarizer 210. The PVA-based polarizer 210 and the first protective layer 220, and the PVA-based polarizer 210 and the second protective layer 230, can be directly laminated to each other. Here, "direct lamination" includes lamination onto the PVA-based polarizer 210 using the self-adhesive properties of the first protective layer 220 and the second protective layer 230, and lamination via an adhesive layer or bonding agent layer. To improve the adhesion to the PVA-based polarizer 210, the first protective layer 220 and the second protective layer 230 can be surface-treated (e.g., corona treatment), or a thin layer such as a primer layer (also called an easy-to-adhere layer) can be formed.

[0080] As a protective layer, resin films with excellent properties such as transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, and tensile strength can be used. The resin film can be a thermoplastic resin film. Specific examples of such resins include cellulose-based resins such as triacetyl cellulose; polyester-based resins such as polyethylene terephthalate and polyethylene naphthalate; polyethersulfone-based resins; polysulfone-based resins; polycarbonate-based resins; polyamide-based resins such as nylon and aromatic polyamides; polyimide-based resins; polyolefin-based resins such as polyethylene, polypropylene, and ethylene-propylene copolymers; cyclic polyolefin-based resins with cyclic and norbornene structures (also known as norbornene-based resins); (meth)acrylic resins such as polymethyl methacrylate; polyarylate-based resins; polystyrene-based resins; polyvinyl alcohol-based resins; and mixtures thereof. Protective films made of the above materials are readily available on the market. In addition, thermosetting or UV-curing resins such as (meth)acrylic acid resins, urethane resins, (meth)acrylate urethane resins, epoxy resins, and silicone resins can also be cited. In this specification, (meth)acrylic acid can refer to either acrylic acid or methacrylic acid.

[0081] 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.

[0082] The protective layer may contain any appropriate additives depending on the purpose. Examples of additives include, but are not limited to, hindered phenolic, phosphorus-based, and sulfur-based antioxidants; light stabilizers, UV absorbers, weather stabilizers, and heat stabilizers; reinforcing materials such as glass fiber and carbon fiber; 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 these additives can be appropriately determined based on the purpose and desired properties.

[0083] In addition, to impart desired surface optical properties or other characteristics, a coating layer (surface treatment layer) may be provided on the outer surface of the protective layer. Specific examples of surface treatment layers include hard coatings, anti-glare layers, anti-reflective layers, antistatic layers, and antifouling layers. There are no particular limitations on the method of forming the surface treatment layer, and known methods can be used. The surface treatment layer may be formed on one side or both sides of the protective film.

[0084] The second protective layer 230 is suitable as an impermeable layer, as described later.

[0085] (The adhesive layer that bonds the PVA polarizer to the protective layer)

[0086] PVA polarizers and their protective layers can be stacked separately via adhesive layers.

[0087] As an adhesive, any suitable adhesive composition (hereinafter also simply referred to as "adhesive") can be used to form it. Specifically, as an adhesive, water-based adhesives, solvent-based adhesives, active energy radiation-curable adhesives, etc., can be used, preferably water-based adhesives, and more preferably water-based adhesives containing polyvinyl alcohol resin and crosslinking agents. When adhesive layers are provided on both sides of the PVA-based polarizer 210, the same adhesive can be used to form it, or different adhesives can be used to form it.

[0088] The thickness of the adhesive layer during application can be set to any suitable value. For example, it can be set in such a way that an adhesive layer with 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.

[0089] (Water-based adhesive)

[0090] As a water-based adhesive, any suitable water-based adhesive can be used. Among these, a water-based adhesive containing polyvinyl alcohol (PVA) resin (PVA-based adhesive) is preferred. The water-based adhesive can be formed by dissolving the PVA-based resin with at least one selected from urea compounds, amide compounds, and hindered amine compounds in water (e.g., pure water). From the viewpoint of adhesion, the average degree of polymerization of the PVA-based resin contained in the water-based adhesive is preferably about 100 to 5500, more preferably 1000 to 4500. From the viewpoint of adhesion, the average degree of saponification is preferably about 85 mol% to 100 mol%, more preferably 90 mol% to 100 mol%.

[0091] As the PVA-based resin contained in the aforementioned water-based adhesive, a PVA-based resin containing acetyl groups is preferred because it exhibits excellent adhesion and durability to the protective film. The acetyl group-containing PVA-based resin can be obtained, for example, by reacting a PVA-based resin with a diene using any method. The degree of acetyl group modification in the acetyl group-containing PVA-based resin is typically 0.1 mol% or more, preferably around 0.1 mol% to 20 mol%.

[0092] 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.

[0093] Regarding the content of PVA-based resin in the water-based adhesive (the proportion of PVA-based resin in the total resin contained in the adhesive), it is preferably 80% by mass or more, more preferably 90% by mass or more, and may also be 100% by mass, based on the total amount of resin in the water-based adhesive.

[0094] (Cross-linking agent, solvent)

[0095] In addition to the PVA-based resins described above, the water-soluble PVA-based adhesives preferably used in this invention may also contain a crosslinking agent as needed. Known crosslinking agents can be used as crosslinking agents. Examples include water-soluble epoxy compounds, dialdehydes, and isocyanates.

[0096] When the PVA resin is a PVA-based resin containing acetyl groups, the crosslinking agent is preferably any one of glyoxal, glyoxylate, and hydroxymethyl melamine, preferably any one of glyoxal and glyoxylate, and particularly preferably glyoxal.

[0097] Furthermore, water-soluble PVA-based adhesives may contain organic solvents. In this case, from the viewpoint of being miscible with water, alcohols are preferred, and among alcohols, methanol or ethanol are more preferred.

[0098] When the aqueous adhesive contains at least one selected from urea compounds, amide compounds, and hindered amine compounds, the content of at least one selected from urea 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 amount of solid components of the aqueous adhesive.

[0099] (Active energy radiation curing adhesive)

[0100] As an active energy ray-cured adhesive, any suitable adhesive can be used as long as it can be cured by irradiation with active energy rays. Examples of active energy ray-cured adhesives include ultraviolet-cured adhesives and electron beam-cured adhesives. Specific examples of curing types of active energy ray-cured adhesives include free radical curing types, cationic curing types, anionic curing types, and combinations thereof (e.g., mixtures of free radical curing types and cationic curing types).

[0101] Examples of the above-mentioned active energy ray-curable adhesives include adhesives containing compounds (e.g., monomers and / or oligomers) with free radical polymerizable groups such as (meth)acrylate groups and (meth)acrylamide groups as curing components. Specific examples of the above-mentioned active energy ray-curable adhesives and their curing methods are described in Japanese Patent Application Publication No. 2012-144690.

[0102] At least one of the adhesive layers between the first protective layer 220 and the PVA-based polarizer 210, and between the second protective layer 230 and the PVA-based polarizer 210, may contain at least one selected from the aforementioned urea compounds, amide compounds, and hindered amine compounds. Only one pair of adhesive layers may contain at least one selected from the urea compounds, amide compounds, and hindered amine compounds, but preferably both contain at least one selected from the urea compounds, amide compounds, and hindered amine compounds.

[0103] (Adhesive layer α (500))

[0104] As the adhesive composition forming the adhesive layer α (500), conventionally known adhesive compositions with excellent optical transparency can be used without particular limitation. For example, adhesive compositions with base polymers such as acrylic resins, urethane resins, silicone resins, and polyvinyl ether resins can be used. Alternatively, active energy radiation-curable adhesive compositions, thermosetting adhesive compositions, etc., can also be used. Among these, adhesive compositions based on acrylic resins with excellent transparency, adhesion, re-peelability, weather resistance, and heat resistance are particularly suitable.

[0105] The adhesive composition may further include crosslinking agents, silane compounds, antistatic agents, etc.

[0106] [(Meth)acrylic resins]

[0107] The (meth)acrylate resin contained in the adhesive composition is preferably a polymer (hereinafter also referred to as "(meth)acrylate polymer") with structural units derived from alkyl methacrylates of the following formula (I) as the main component (e.g., containing 50 parts by mass or more relative to 100 parts by mass of the structural units of the (meth)acrylate resin).

[0108] It should be noted that in this specification, (meth)acrylic resin can refer to either acrylic resin or methacrylic resin, and the "(meth)" in (meth)acrylate, etc., has the same meaning.

[0109] [Chemical Formula 7]

[0110]

[0111] [In the formula, R] 10 R represents a hydrogen atom or a methyl group. 20 The alkyl group represents an alkyl group having 1 to 20 carbon atoms. This alkyl group can have any of the following structures: straight-chain, branched, or cyclic. The hydrogen atoms of this alkyl group can be substituted with alkoxy groups having 1 to 10 carbon atoms.

[0112] Examples of (meth)acrylates represented by formula (I) include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-nonyl (meth)acrylate, and isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, n-dodecyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, stearyl (meth)acrylate, and tert-butyl (meth)acrylate. Specific examples of alkyl acrylates containing alkoxy groups include 2-methoxyethyl (meth)acrylate and ethoxymethyl (meth)acrylate. Preferably, it contains n-butyl (meth)acrylate or 2-ethylhexyl (meth)acrylate, and particularly preferably contains n-butyl (meth)acrylate.

[0113] (Meth)acrylate polymers may contain structural units derived from other monomers besides structural unit (I). There may be one or more structural units derived from other monomers. Examples of other monomers that may be included in (meth)acrylate polymers include monomers with polar functional groups, monomers with aromatic groups, and acrylamide monomers.

[0114] Examples of monomers with polar functional groups include (meth)acrylates. Examples of polar functional groups include hydroxyl groups; carboxyl groups; substituted or unsubstituted amino groups substituted with alkyl groups having 1 to 6 carbon atoms; and heterocyclic groups such as epoxy groups. Monomers with polar functional groups can be monomers containing carboxyl groups, such as acrylic acid and maleic acid.

[0115] Relative to all 100 parts by mass of the (meth)acrylate polymer, the content of structural units derived from monomers having polar functional groups in the (meth)acrylate 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.

[0116] Examples of monomers containing aromatic groups include (meth)acrylates that have one (meth)acryloyl group and one or more aromatic rings (e.g., benzene ring, naphthalene ring, etc.) within the molecule, and that contain phenyl, phenoxyethyl, or benzyl groups. By including these structural units, the whitening phenomenon of polarizers that occurs under high temperature and high humidity conditions can be suppressed.

[0117] Relative to all 100 parts by mass of the (meth)acrylate polymer, the content of structural units derived from monomers having aromatic groups in the (meth)acrylate 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.

[0118] Examples of acrylamide monomers include N-(methoxymethyl)acrylamide, N-(ethoxymethyl)acrylamide, N-(propoxymethyl)acrylamide, N-(butoxymethyl)acrylamide, and N-(2-methylpropoxymethyl)acrylamide. By incorporating these structural units, the exudation of additives such as antistatic agents described later can be suppressed.

[0119] In addition, structural units derived from other monomers besides structural unit (I) may also include structural units derived from styrene monomers, structural units derived from vinyl monomers, structural units derived from monomers having multiple (meth)acryloyl groups within the molecule, etc.

[0120] The weight-average molecular weight (hereinafter also referred to as "Mw") of the (meth)acrylic resin (1) is preferably 500,000 to 2,500,000. If the weight-average molecular weight is 500,000 or more, the durability of the adhesive layer under high temperature and high humidity conditions can be improved. If the weight-average molecular weight is 2,500,000 or less, the workability when applying a coating liquid containing the adhesive composition becomes good. The molecular weight distribution (Mw / Mn) shown by the ratio of weight-average molecular weight (Mw) to number-average molecular weight (hereinafter also referred to as "Mn") is usually 2 to 10. In this specification, "weight-average molecular weight" and "number-average molecular weight" are polystyrene conversion values ​​determined by gel permeation chromatography (GPC).

[0121] When dissolving a (meth)acrylic resin in ethyl acetate to prepare a 20% by mass solution, the viscosity at 25°C is preferably 20 Pa·s or less, more preferably 0.1 to 15 Pa·s. If the viscosity of the (meth)acrylic resin at 25°C is within the above range, it helps to improve the durability and reprocessability of the polarizing plate containing the adhesive layer formed from the above resin. The above viscosity can be measured using a Brookfield viscometer.

[0122] The glass transition temperature (Tg) of the (meth)acrylic resin 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. It should be noted that the glass transition temperature can be determined using a differential scanning calorimeter (DSC).

[0123] (Meth)acrylic resins may contain two or more (meth)acrylate polymers. Examples of such (meth)acrylate polymers include (meth)acrylate polymers with low molecular weights, where the structural unit (I) derived from the above-mentioned (meth)acrylate is the main component and the weight-average molecular weight is in the range of 50,000 to 300,000.

[0124] (Meth)acrylic resins are typically manufactured using known polymerization methods such as solution polymerization, bulk polymerization, suspension polymerization, and emulsion polymerization. In the manufacture of (meth)acrylic resins, polymerization is usually carried out in the presence of a polymerization initiator. The amount of polymerization initiator used is typically 0.001 to 5 parts by mass relative to 100 parts by mass of all monomers constituting the (meth)acrylic resin. (Meth)acrylic resins can also be manufactured by polymerization using active energy rays such as ultraviolet light.

[0125] [Cross-linking agent]

[0126] The adhesive composition preferably includes a crosslinking agent. Commonly used crosslinking agents include isocyanate compounds, epoxy compounds, aziridine compounds, metal chelate compounds, peroxides, etc., and isocyanate compounds are preferred, especially from the viewpoints of the pot life of the adhesive composition, the crosslinking rate and the durability of the polarizer.

[0127] Isocyanate compounds are compounds having at least two isocyanate groups (-NCO) within their molecules. Specifically, examples include toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, phenylenediamine diisocyanate, hydrogenated phenylenediamine diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, naphthalene diisocyanate, and triphenylmethane triisocyanate. Additionally, examples include adducts, dimers, and trimers of these isocyanate compounds obtained by reacting these isocyanate compounds with polyols such as glycerol and trimethylolpropane. Combinations of two or more isocyanate compounds can also be used.

[0128] The proportion of crosslinking agent relative to 100 parts by weight of (meth)acrylic resin is, for example, 0.01 to 10 parts by weight, preferably 0.05 to 5 parts by weight, and more preferably 0.1 to 1 parts by weight.

[0129] [Silane compounds]

[0130] The adhesive composition may further contain silane compounds.

[0131] Examples of silane compounds include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(2-methoxyethoxy)silane, 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropyltriethoxysilane, 3-epoxypropoxypropylmethyldimethoxysilane, 3-epoxypropoxypropylethoxydimethylsilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane.

[0132] In addition, silane compounds may include oligomers derived from the aforementioned silane compounds.

[0133] The content of silane compound in the adhesive composition is typically 0.01 to 10 parts by weight relative to 100 parts by weight of (meth)acrylic resin, preferably 0.05 to 5 parts by weight. If the content of silane compound is 0.01 parts by weight or more, there is a tendency to improve the adhesion between the adhesive layer and the adherend; if the content is 10 parts by weight or less, there is a tendency to suppress the seepage of silane compound from the adhesive layer.

[0134] <Antistatic Agent>

[0135] The adhesive composition may further include an antistatic agent. Known antistatic agents are examples, and ionic antistatic agents are suitable. As the cationic component constituting the ionic antistatic agent, organic and inorganic cations are examples. As organic cations, pyridinium cations, imidazolium cations, ammonium cations, sulfonium cations, phosphonium cations, etc., are examples. As inorganic cations, alkali metal cations such as lithium cations, potassium cations, sodium cations, cesium cations, etc., and alkaline earth metal cations such as magnesium cations, calcium cations, etc., are examples. As the anionic component constituting the ionic antistatic agent, it can be any of inorganic and organic anions; from the perspective of superior antistatic performance, anionic components containing fluorine atoms are preferred. As an anionic component containing fluorine atoms, hexafluorophosphate anion (PF6) is an example. - ), bis(trifluoromethanesulfonyl)imide anion [(CF3SO2)2N] - ], bis(fluorosulfonyl)imide anion [(FSO2)2N - Anions, etc.

[0136] From the perspective of excellent antistatic properties and long-term stability of the adhesive composition, ionic antistatic agents that are solid at room temperature are preferred.

[0137] The content of antistatic agent relative to 100 parts by weight of (meth)acrylic resin is, for example, 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight, and more preferably 1 to 7 parts by weight.

[0138] The adhesive composition may contain one or more UV absorbers, solvents, crosslinking catalysts, tackifying resins (tackifiers), plasticizers, and other additives. Additionally, incorporating UV-curable compounds into the adhesive composition to form an adhesive layer and then curing it under UV light is also useful for creating a harder adhesive layer.

[0139] The adhesive layer α (500) can be formed, for example, by dissolving or dispersing the above-mentioned adhesive composition in a solvent to prepare an adhesive composition containing a solvent, and then applying it to the surface of the layer on which the adhesive layer is disposed and drying it.

[0140] 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.

[0141] The adhesive layer α (500) may contain at least one selected from the above-mentioned urea compounds, amide compounds and hindered amine compounds.

[0142] Suitable is that the peel force between the adhesive layer α and the second protective layer 230 is greater than the peel force between the surface protective film 100 and the first protective layer, and the peel force between the surface protective film 100 and the first protective layer is greater than the peel force between the adhesive layer α and the diaphragm 600.

[0143] The peel force between the adhesive layer α and the diaphragm 600 can be greater than 0.02 N / 25 mm or less than 0.1 N / 25 mm. In this specification, the peel force is based on the "180-degree peel test method" of JIS Z0237:2009 (test method for adhesive tapes / sheets).

[0144] The peel force between the adhesive layer α and the second protective layer 230 can be 0.5N / 25mm or more.

[0145] (Surface protective film 100)

[0146] In this embodiment, the surface protective film 100 sequentially comprises an adhesive layer 110, a substrate layer 120, an adhesive layer 130, a moisture-absorbing layer 140, a moisture-impermeable layer 150, and a substrate layer 160, starting from the PVA-based polarizer 210 side. The surface protective film 100 can protect the surface of the polarizer 200 on the side of the first protective layer 220, and can be peeled off from the first protective layer 220 together with the adhesive layer 110 as needed.

[0147] (Substrate layers 120 and 160)

[0148] Substrate layers 120 and 160 function as substrates supporting the surface protective film 100.

[0149] The substrate layers 120 and 160 can be thermoplastic resin films, such as polyolefin resins like polyethylene resins and polypropylene resins; cyclic polyolefin resins; polyester resins like polyethylene terephthalate and polyethylene naphthalate; polycarbonate resins; and (meth)acrylic resins. Polyester resins such as polyethylene terephthalate are preferred. Each substrate layer can be a single-layer structure or a multilayer structure with two or more layers. The resin film for the protective film can be a film that has undergone stretching treatment such as uniaxial stretching or biaxial stretching.

[0150] The thickness of the substrate layers 160 and 120 can be, for example, 30 to 200 μm, preferably 30 to 150 μm, and more preferably 30 to 120 μm.

[0151] It is not necessary to have both substrate layer 120 and substrate layer 160. For example, only one of them may be present. In addition, if at least one of the moisture-impermeable layer 150 and the moisture-absorbing layer 140 has sufficient strength to function as a substrate layer, neither of the substrate layer 120 nor substrate layer 160 may be present.

[0152] (Adhesive layer 110 and adhesive layer 130)

[0153] Adhesive layer 110 is used to fix substrate layer 120 to first protective layer 220. Adhesive layer 130 is used to fix moisture-absorbing layer 140 and substrate layer 120. As adhesive layers 110 and 130, adhesive layers illustrated in adhesive layer α (500) can be used.

[0154] From the viewpoint of properly peeling the surface protective film 100 from the polarizing plate 200, the peel force between the adhesive layer 110 and the first protective layer 220 can be 0.05 N / 25 mm or more, or 0.2 N / 25 mm or less.

[0155] In the absence of substrate layer 120, adhesive layer 130 is not required.

[0156] The thickness of the adhesive layers 110 and 130 is preferably 5 μm or more, or 10 μm or more, or 15 μm or more. In addition, it is preferably 30 μm or less, or 25 μm or less, or 20 μm or less.

[0157] (Impermeable layer 150)

[0158] The moisture-impermeable layer 150 is a layer that sufficiently impedes the permeability of moisture. In this specification, the moisture-impermeable layer refers to a layer with a permeability A of 1.5 g / m³, measured by the wet / dry sensor method (so-called Lyssy method) according to JIS K7129-1:2019 at 40°C and 90% relative humidity. 2 Layers below / day.

[0159] The moisture permeability (A) of the impermeable layer 150 can be 1.5 g / m². 2 For doses below 1 / day, 0.3g / m² is also acceptable. 2 Below / day, or even less than 0.2g / m 2 / sky.

[0160] The moisture permeability B of the impermeable layer 150, measured by the differential pressure sensor method (JIS K 7129-5:2016) at 40℃ and 90% relative humidity, can be less than 5.0 × 10⁻⁶. -4 g / m 2 / sky.

[0161] Examples of layers exhibiting such moisture permeability include cyclic olefin polymer films and aluminum layers (such as aluminum foil and aluminum vapor-deposited films).

[0162] A 150mm thick impermeable layer can maintain a moisture permeability of 1.5g / m². 2The appropriate setting should be made within the range of less than / day. Specifically, for cyclic olefin polymer films, the setting can be 10–100 μm, and for aluminum foil, it can be 5–100 μm.

[0163] (Moisture-absorbing layer 140)

[0164] The moisture-absorbing layer is a layer capable of fully absorbing water. In this specification, the water absorption rate is 0.3 g / m³ after storage at 23°C and 55% relative humidity for 14 days. 2 The above layers are called the moisture-absorbing layer. The moisture-absorbing layer can absorb up to 1.0 g / m³ of water. 2 The above can also be 3.0 g / m 2 above.

[0165] As materials constituting the moisture-absorbing layer, compositions comprising water-absorbing resins or desiccants can be used. As water-absorbing resins, polyvinylpyrrolidone-based resins, polyacrylic acid, sodium polyacrylate, polyvinylamine, sodium polyglutamate, polyvinyl alcohol-based resins, and cellulose derivatives can be used. As desiccants, chemical desiccants such as metal halides, metal oxides, and sulfates, and physical desiccants such as hydrophilic zeolites and silica gel can also be used. Desiccants can be used alone or in combination.

[0166] The composition comprising a hygroscopic agent may be, for example, a composition comprising a hygroscopic agent and a resin, wherein the hygroscopic agent may be dispersed in the resin. The resin used for dispersion may be, for example, a polyolefin resin, a polyester resin, a polyamide resin, or a vinyl polymer.

[0167] Examples of polyolefin resins include polyethylene resins and polypropylene resins.

[0168] Examples of metal oxides include calcium oxide and aluminum oxide. Examples of metal halides include calcium chloride. Examples of sulfates include magnesium sulfate.

[0169] As hydrophilic zeolites, for example, type A, type X, or type LSX zeolites can be used.

[0170] From the perspective of ensuring good moisture absorption capacity, the content of desiccant is preferably 1% by mass or more relative to the overall mass of the moisture-absorbing layer.

[0171] <Method for making the moisture-absorbing layer>

[0172] There are no particular limitations on the method for manufacturing the moisture-absorbing layer; well-known or conventional methods can be used. For example, it can be manufactured using wet lamination, dry lamination, solvent-free dry lamination, extrusion lamination, T-die co-extrusion molding, co-extrusion lamination, blow molding, or any other method. For instance, a moisture-absorbing film can be obtained by melt-blending 80 parts by weight of polyethylene resin and 20 parts by weight of calcium oxide.

[0173] At least one of the substrate layer 120, substrate layer 160, adhesive layer 110, and adhesive layer 130 of the surface protective film 100 may contain an antistatic agent. Alternatively, an antistatic layer containing an antistatic agent may be provided on the side of the substrate layer 120 opposite to the side where the adhesive layer 110 is laminated, or on the side of the substrate layer 160 opposite to the side where the moisture-impermeable layer 150 is provided.

[0174] Examples of antistatic agents include ionic compounds, ionic polymers, conductive polymers, conductive microparticles, surfactants, hydrolyzable organosilicon compounds, and their condensates. Ionic compounds are compounds containing inorganic or organic cations, as well as inorganic or organic anions. Examples of ionic polymers include polymers containing ammonium salts or sodium sulfonates. Examples of conductive polymers include polyacetylene, polyphenylene, and polystyrene sulfonic acid. Two or more of the aforementioned ionic compounds can be used as antistatic agents.

[0175] (Diaphragm 600)

[0176] The diaphragm 600 has a substrate layer 610. The diaphragm 600 can protect the surface of the adhesive layer α (500) and can be peeled off from the adhesive layer α (500) as needed.

[0177] (Substrate layer 610)

[0178] The substrate layer 610 is a layer that supports the diaphragm 600. The substrate layer 610 can be any of the substrate layers 120 and 160. The thickness of the substrate layer 610 can be, for example, 30–200 μm, preferably 30–150 μm, and more preferably 30–120 μm. The side of the substrate layer 610 that contacts the adhesive layer α can be subjected to a known demolding process.

[0179] The substrate layer 610 of the diaphragm 600 may contain an antistatic agent. Alternatively, an antistatic layer containing an antistatic agent may be provided on the surface of the substrate layer 610 opposite to the adhesive layer α (500).

[0180] Examples of antistatic agents include ionic compounds, ionic polymers, conductive polymers, conductive microparticles, surfactants, hydrolyzable organosilicon compounds, and their condensates. Ionic compounds are compounds containing inorganic or organic cations, as well as inorganic or organic anions. Examples of ionic polymers include polymers containing ammonium salts or sodium sulfonates. Examples of conductive polymers include polyacetylene, polyphenylene, and polystyrene sulfonic acid. Two or more of the aforementioned ionic compounds can be used as antistatic agents.

[0181] For the optical laminate, preferably at least one of the following: the PVA-based polarizer 210, the adhesive layer between the first protective layer 220 and the PVA-based polarizer 210 (not shown), the adhesive layer between the second protective layer and the PVA-based polarizer (not shown), and the adhesive layer α (500) comprises at least one selected from urea compounds, amide compounds, and hindered amine compounds. Multiple of these may comprise at least one selected from urea compounds, amide compounds, and hindered amine compounds. Regarding urea compounds, amide compounds, and hindered amine compounds, as described in the section on PVA-based polarizers.

[0182] When the optical laminate contains at least one selected from urea compounds, amide compounds, and hindered amine compounds, the content of at least one selected from urea compounds, amide compounds, and hindered amine compounds, based on the solid composition of the optical laminate, 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.

[0183] (Second Implementation)

[0184] Next, refer to Figure 2 The optical laminate of the second embodiment will be described. Hereinafter, repeated descriptions will be omitted, and only the differences will be explained.

[0185] The difference between this embodiment and the first embodiment is that, on the side of the substrate layer 610 opposite to the adhesive layer α (500), the diaphragm 600 sequentially comprises an adhesive layer 620, a moisture-impermeable layer 640, and a substrate layer 650, starting from the PVA polarizer side. That is, in the second embodiment, the surface protective film 100 has both a moisture-impermeable layer and a moisture-absorbing layer, and the diaphragm 600 has a moisture-impermeable layer. It should be noted that the first protective layer 220 or the second protective layer 230 may or may not be a moisture-impermeable layer.

[0186] The adhesive layer 620 is the same as the adhesive layer 130 described above.

[0187] The moisture-impermeable layer 640 is the same as the moisture-impermeable layer 150 mentioned above.

[0188] The substrate layer 650 is the same as the substrate layer 160 described above.

[0189] It should be noted that the substrate layer 650 is arbitrary. Furthermore, if the moisture-impermeable layer 640 or the substrate layer 650 has sufficient strength, the substrate layer 610 is not necessary, and in this case, the adhesive layer 620 is not required.

[0190] (Third implementation method)

[0191] Next, refer to Figure 3 The optical laminate of the third embodiment will be described.

[0192] The difference between this embodiment and the second embodiment is that the separator 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-based polarizer 210 than the moisture-impermeable layer 640. The moisture-absorbing layer 630 is the same as the moisture-absorbing layer 140 described above. That is, the third embodiment is one in which both the surface protective film 100 and the separator 600 have moisture-impermeable layers and moisture-absorbing layers.

[0193] (Fourth Implementation)

[0194] Next, refer to Figure 4 The optical laminate of the fourth embodiment will be described.

[0195] The optical laminate 1000 of the fourth embodiment differs from that of 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 substrate layer 160, and the separator 600 has an adhesive layer 620, a moisture-absorbing layer 630, a moisture-impermeable layer 640, and a substrate layer 650 sequentially from the PVA polarizer 210 side on the side of the substrate layer 610 opposite to the PVA polarizer 210 side. That is, the fourth embodiment is characterized by the surface protective film 100 lacking both a moisture-absorbing and moisture-impermeable layer, while the separator 600 has both a moisture-impermeable and moisture-absorbing layer.

[0196] 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 substrate layer 650 is the same as the substrate layer 160 of the first embodiment.

[0197] It is not necessary to have both substrate layer 610 and substrate layer 650. For example, only one of them may be present. In addition, if at least one of the moisture-impermeable layer 640 and the moisture-absorbing layer 630 has sufficient strength to function as a substrate layer, both substrate layer 610 and substrate layer 650 may not be present.

[0198] In the absence of substrate layer 610, adhesive layer 620 is not required.

[0199] In this embodiment, the first protective layer 220 is suitable as a moisture-proof layer.

[0200] (Fifth Implementation)

[0201] Next, refer to Figure 5 The optical laminate of the fifth embodiment will be described.

[0202] The optical laminate 1000 of the fifth embodiment differs from that of the fourth embodiment in that, on the side of the substrate layer 120 opposite to the PVA polarizer 210, the surface protective film 100 sequentially comprises an adhesive layer 130, a moisture-impermeable layer 150, and a substrate layer 160, starting from the PVA polarizer 210 side. That is, in the fifth embodiment, the surface protective film 100 has a moisture-impermeable layer, and the separator 600 has a moisture-impermeable layer and a moisture-absorbing layer.

[0203] It should be noted that it is not necessary to have both substrate layer 120 and substrate layer 160. For example, only one of them may be present. In addition, if the moisture-impermeable layer 150 has sufficient strength to function as a substrate layer, both substrate layer 120 and substrate layer 160 may not be present.

[0204] In the absence of substrate layer 120, adhesive layer 130 is not required.

[0205] (How to use optical laminates)

[0206] Next, an example of a manufacturing method for an image display device using an optical laminate 1000 will be described.

[0207] First, the diaphragm 600 is peeled off from the optical laminate 1000, and the laminate of the surface protective film 100 and the polarizer 200 is attached to the image display unit via the adhesive layer α.

[0208] Next, peel the surface protective film 100 from the polarizing plate 200. Then, attach the front panel or touch panel to the peeled surface of the polarizing plate via an adhesive layer or the like.

[0209] This allows for the creation of an image display device with a layered structure consisting of an image display unit, a polarizing plate, a front panel, or a touch panel. It should be noted that no heat treatment of the polarizing plate is required from the time the polarizing plate is attached to one side of the image display unit until the front panel or touch panel is attached to the other side of the polarizing plate.

[0210] (Effects)

[0211] According to the optical laminate of this embodiment, yellowing of PVA-based polarizers in high-temperature environments in image display devices with layered structures such as image display units / polarizers / front panels or touch panels can be suppressed. The reason is not yet clear, but the mechanism is believed to be as follows.

[0212] In the above embodiments, at least one of the surface protective film 100 and the separator 600 has a combination of an impermeable layer 150 and a moisture-absorbing layer 140 disposed closer to the PVA-based polarizer 210 than the impermeable layer 150, or a combination of an impermeable layer 640 and a moisture-absorbing layer 630 disposed closer to the PVA-based polarizer 210 than the impermeable layer 640. Therefore, the impermeable layer can suppress the movement of moisture from the outside of the optical laminate to the moisture-absorbing layer, and the moisture-absorbing layer can absorb moisture within the PVA-based polarizer, thereby reducing the moisture content within the PVA-based polarizer. Therefore, it is believed that an image display device having an image display panel, a polarizer, and a front panel / touch panel laminated can be obtained with reduced moisture within the PVA-based polarizer. Therefore, even when exposed to high-temperature environments, the yellowing of the PVA-based polarizer in this image display device is minimal. It should be noted that if PVA polarizers contain moisture, the decomposition of iodine complexes under high temperature conditions is promoted, and free iodine becomes a catalyst for polyene formation, resulting in yellowing.

[0213] In the case where only one of the surface protective film 100 and the diaphragm 600 has a moisture-impermeable layer and a moisture-absorbing layer, as in the first embodiment ( Figure 1 In the case where the second protective layer 230 is a moisture-proof layer, or in the fourth embodiment ( Figure 4 As in the case where the first protective layer 220 is an impermeable layer, when the protective layer on the opposite side of the PVA polarizer 210 and the surface protective film 100 and the separator 600 is an impermeable layer, the moisture supply from the opposite side is also suppressed, resulting in a higher effect.

[0214] Furthermore, in the case where only one of the surface protective film 100 and the diaphragm 600 has a moisture-impermeable layer and a moisture-absorbing layer, as in the second embodiment ( Figure 2 ) or the 5th embodiment ( Figure 5 The effect is even greater when one of the surface protective film 100 and the diaphragm 600 has a moisture-proof layer.

[0215] Additionally, as in the third embodiment ( Figure 3 As shown in the figure, the surface protective film 100 and the diaphragm 600 have a moisture-impermeable layer and a moisture-absorbing layer, respectively, which results in a higher effect.

[0216] Furthermore, the effect is enhanced when at least one of the following selected from PVA-based polarizers, adhesive layers between the first protective layer and the PVA-based polarizer, adhesive layers between the second protective layer and the PVA-based polarizer, and adhesive layer α comprises at least one selected from urea compounds, amide compounds, and hindered amine compounds.

[0217] Example

[0218] (Preparation of each membrane)

[0219] The following films are prepared.

[0220] · Laminated film A: a laminated film comprising a PET film (PET1) / a moisture-impermeable layer (aluminum foil (AL1)) / a moisture-absorbent layer (obtained by cutting Kyusyu-kun (Japanese: 吸湿くん) (R) (trade name TO-A2) obtained from Maruto Sangyo Co., Ltd.).

[0221] The moisture vapor transmission rate A of the aluminum foil (AL1) as the moisture-impermeable layer is less than 0.2 g / m 2 / day, and the moisture vapor transmission rate B is less than 5.0×10 -4 g / m 2 / day.

[0222] The water absorption of the moisture-absorbent layer is 6.62 g / m 2 .

[0223] · Laminated film B: a laminated film comprising a PET film (PET2) / an adhesive layer A.

[0224] The peel strength between the adhesive layer A and TAC of a polarizing plate is 0.06 N / 25 mm.

[0225] The moisture vapor transmission rate A of the PET2 film is 15 g / m 2 / day.

[0226] · PET3: a film obtained by subjecting one surface of a PET film to release treatment

[0227] · AL2: aluminum foil (moisture vapor transmission rate A is less than 0.2 g / m 2 / day, and moisture vapor transmission rate B is less than 5.0×10 -4 g / m 2 / day.)

[0228] · COP: a cycloolefin resin film (thickness: 51 μm, moisture vapor transmission rate A: 1.5 g / m 2 / day.)

[0229] · TAC: a triacetyl cellulose film (thickness: 40 μm)

[0230] · Adhesive layer B: peel strength to TAC of a polarizing plate is 15 N / 25 mm

[0231] peel strength to PET3 is 0.04 N / 25 mm

[0232] · Adhesive layer C: an acrylic adhesive

[0233] Preparation method of water-based adhesives A to G

[0234] Z-200 (acetylacetyl-modified PVA manufactured by Mitsubishi Chemical Co., Ltd.) was dissolved in pure water to obtain a 5.7 wt% aqueous solution. Pure water, the above 5.7 wt% Z-200 aqueous solution, a 40 wt% glyoxal solution (manufactured by Fujifilm and Wako Pure Chemical Industries Co., Ltd.), and the additives shown in Table 1 were mixed in a weight ratio of water / Z-200 (solid component) / glyoxal (solid component) / additives of 100 / 3.0 / 0.15 / X to obtain aqueous 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.

[0235] For the obtained water-based adhesives A to G, the concentration of additives per 1 kg of adhesive can be calculated using the following formula.

[0236] Additive concentration (mol / kg) = Additive dosage (kg) / Additive molecular weight (kg / mol) × 1 / Adhesive preparation amount (kg)

[0237] [Table 1]

[0238]

[0239] Manufacturing method of PVA polarizer

[0240] A 30 μm thick strip of polyvinyl alcohol film (VF-PE #3000 manufactured by Kuraray Co., Ltd.) is continuously conveyed and immersed in a swelling bath containing pure water at 20°C for a residence time of 31 seconds (swelling process). Then, the film pulled from the swelling bath is immersed in a dyeing bath containing iodine at 30°C with a potassium iodide / water ratio of 2 / 100 (by weight) for a residence time of 122 seconds (dyeing process). Next, the film pulled from the dyeing bath is immersed in a crosslinking bath at 56°C with a potassium iodide / boric acid / water ratio of 12 / 4.1 / 100 (by weight) for a residence time of 70 seconds, followed by an immersion in a crosslinking bath at 40°C with a potassium iodide / boric acid / water ratio of 9 / 2.9 / 100 (by weight) for a residence time of 13 seconds (crosslinking process).

[0241] In the dyeing and crosslinking processes, axial stretching in the MD direction is performed by roller stretching in a bath. The total stretching ratio based on the raw film is set to 5.5 times. Next, the film drawn from the crosslinking bath is immersed in a cleaning bath containing pure water at 5°C for a residence time of 3 seconds (cleaning process), and then introduced into a drying oven at 80°C for drying for a residence time of 190 seconds (drying process) to obtain a polarizing film. In this embodiment, the thickness of the polarizing film is 12 μm.

[0242] Fabrication of polarizing plates A to G

[0243] Using a roller laminator, a 40 μm thick triacetyl cellulose membrane that had undergone saponification was bonded to both sides of a PVA-based polarizer using an aqueous adhesive as described in Table 1. The resulting laminate was dried at 80°C for 3 minutes to obtain polarizers A to G. The polarizers are configured as TAC / PVA-based polarizer / TAC.

[0244] Fabrication of surface protective film A

[0245] • A surface protective film A is obtained by laminating the moisture-absorbing layer side of the laminated film A on the PET2 surface of the laminated film B via the adhesive layer C.

[0246] The surface protective film A is composed of laminated film A (PET1 / impermeable layer (AL1) / moisture-absorbing layer) / adhesive layer C / laminated film B (PET2 / adhesive layer A).

[0247] Fabrication of surface protective film B

[0248] • A surface protective film B is obtained by laminating COP onto the PET2 surface of laminated film B via adhesive layer C.

[0249] The surface protective film B is composed of COP / adhesive layer C / laminated film B (PET2 / adhesive layer A).

[0250] Fabrication of surface protective film C

[0251] • AL2 is laminated onto the surface of PET2 of laminated film B via adhesive layer C to obtain surface protective film C.

[0252] The surface protective film C is composed of AL2 / adhesive layer C / laminated film B (PET2 / adhesive layer A).

[0253] Production of diaphragm A

[0254] • A separator A is obtained by laminating COP through adhesive layer C on the side of PET3 opposite to the demolding surface.

[0255] The diaphragm A is composed of PET3 / adhesive layer C / COP.

[0256] Production of diaphragm B

[0257] • AL2 was laminated on the side of PET3 opposite to the demolding surface to obtain diaphragm B.

[0258] The membrane B is composed of PET3 / adhesive layer C / AL2.

[0259] Preparation of diaphragm C

[0260] • A diaphragm C is obtained by laminating the moisture-absorbing layer side of film A with adhesive layer C on the side of PET3 opposite to the demolding treatment surface.

[0261] The membrane C is composed of PET3 / adhesive layer C / laminated membrane A (moisture-absorbing layer / impermeable layer (AL1) / PET1).

[0262] Fabrication of optical laminates (polarizing plates with moisture-absorbing layers)

[0263] <Example 1>

[0264] A TAC surface of polarizing plate A is corona treated. On the corona-treated surface, adhesive B and diaphragm A (PET3 / adhesive layer C / COP) are sequentially laminated using a roller laminator.

[0265] Next, using a roller laminator, a surface protective film A was laminated onto the outside of another TAC of polarizing plate A to obtain an optical laminate (polarizing plate with a moisture-absorbing layer). The optical laminate was stored for 14 days under conditioned conditions of 23°C and 55% relative humidity.

[0266] The optical laminate is composed of a surface protective film A (PET1 / impermeable layer (AL1) / moisture-absorbing layer / adhesive C / PET2 / adhesive A) / polarizer A (TAC / polarizer / TAC) / adhesive layer B / separator A (PET3 / adhesive layer C / COP).

[0267] <Examples 2-15, Comparative Examples 1-2>

[0268] By replacing the diaphragm, surface protective film, and polarizing plate with the diaphragm and surface protective film listed in Table 2, and otherwise operating in the same manner as in Example 1, an optical laminate was obtained. Diaphragms A to C were laminated with PET3 as the polarizing plate side, and the surface protective film was laminated with adhesive layer A as the polarizing plate side. The optical laminates of Examples 1 and 2 are the second embodiments in this specification, the optical laminates of Examples 3 to 8 are the fifth embodiments, and the laminates of Examples 9 to 15 are the third embodiments.

[0269] It should be noted that in Comparative Examples 1 and 2, laminated film B was used as the surface protective film, and PET3 was used as the separator.

[0270] Preparation of samples for durability evaluation <Examples 1-15 and Comparative Example 1>

[0271] The obtained optical laminate (polarizer with moisture-absorbing layer) was cut into 30mm sections along the MD direction (absorption axis of the polarizer) and 30mm sections along the TD direction (orthogonal to the absorption axis of the polarizer). The diaphragm was peeled off, and adhesive layer B was bonded to the center of a 40mm × 40mm × 0.7mm thick alkali-free glass. The laminate at this point consisted of a surface protective film / polarizer / adhesive layer B / alkali-free glass. After placing the laminate at 23°C and 55% relative humidity for 7 days, the surface protective film was peeled off, and a 30mm × 30mm × 0.15mm thick cover glass was bonded to the surface of the polarizer using a 25μm thick acrylic adhesive, yielding a sample for durability evaluation.

[0272] The sample used for durability evaluation consists of cover glass / adhesive / polarizing plate (TAC / polarizing film / TAC) / adhesive layer B / alkali-free glass.

[0273] Preparation of samples for durability evaluation <Comparative Example 2>

[0274] The obtained optical laminate (polarizer with moisture-absorbing layer) was cut into 30mm sections along the MD direction (absorption axis of the polarizer) and 30mm sections along the TD direction (orthogonal to the absorption axis of the polarizer). The diaphragm was peeled off, and adhesive layer B was bonded to the center of a 40mm × 40mm × 0.7mm thick alkali-free glass. The laminate at this point consisted of a surface protective film / polarizer / adhesive layer B / alkali-free glass. The laminate was heated in an oven at 95°C for 3 hours and stored at 23°C and 55% relative humidity for 24 hours. The surface protective film was then peeled off, and a 30mm × 30mm × 0.15mm thick cover glass was bonded to the surface of the polarizer using an acrylic adhesive with a thickness of 25μm, yielding a sample for durability evaluation.

[0275] The sample used for durability evaluation consists of cover glass / adhesive / polarizing plate (TAC / polarizing film / TAC) / adhesive layer B / alkali-free glass.

[0276] (Moisture permeability measurement)

[0277] (Determination of water permeability A (Lyssy method))

[0278] • Detection method: Humidity sensor method (based on JIS K7129-1:2019)

[0279] • Measuring apparatus: Lyssy L80 series water vapor transmission meter

[0280] • Measurement conditions: 40℃, 90% relative humidity

[0281] • Measurement area: 5.0 × 10 -3 m 2

[0282] • Limit of determination: 0.2 g / m 2 / sky

[0283] ·method:

[0284] (1) Insert and fix the sample between the upper chamber and the lower chamber (saturated water vapor) where the humidity sensor is installed.

[0285] (2) Dry the upper chamber to the predetermined level (lower humidity limit).

[0286] (3) Humidify the upper chamber by passing water vapor through the sample, and measure the time it takes for the humidity of the upper chamber to change from 9.9% to 10.1%. Calculate the transmittance A according to the following formula.

[0287] WVTR sample (g / m 2 / day) = WVTR std .×T std . / T sample

[0288] WVTR std .: Water vapor transmission rate of standard sample (g / m 2 / sky)

[0289] T std .: The time it takes for the standard sample to change from 9.9% humidity to 10.1%

[0290] T sample The time it takes for the humidity of the test sample to change from 9.9% to 10.1%.

[0291] (Determination of moisture permeability B (DELTAPERM))

[0292] • Detection method: Differential pressure sensor method (based on JIS K 7129-5:2016)

[0293] Model: Standard 1-chamber manual type DP-ST1 CM

[0294] • Measurement conditions: 40℃, 90% relative humidity

[0295] ·method:

[0296] (1) Insert and fix the sample between the upper chamber equipped with a steam supply tank and the lower chamber equipped with a pressure sensor.

[0297] (2) Set the constant temperature bath to 40°C and dry the upper and lower chambers by vacuum exhaust.

[0298] (3) Make the upper and lower chambers sealed, introduce water vapor at 40°C and 90% relative humidity from the supply side, and calculate WVTR based on the pressure change of the lower chamber relative to time.

[0299] • Limit of determination: 5.0 × 10 -4 g / m 2 / sky

[0300] (Specifications for the water absorption capacity of the moisture-absorbing layer)

[0301] The amount of water absorbed by the moisture-absorbing layer is determined by the following method.

[0302] The absorbent layer, cut into 100×100mm pieces, was vacuum dried at 23°C for 8 hours, and its initial weight was measured. Next, the weight was measured after 2 weeks of storage at 23°C and 55% relative humidity, and the water absorption was calculated using the following formula.

[0303] Water absorption rate [g / m] 2 [] = (Weight after storage at 23℃ and 55% relative humidity - Initial weight) × 100

[0304] (Determination of the water absorption capacity of the moisture-absorbing layer in laminated membrane A (Moisture Absorber (R)))

[0305] The moisture absorber (R) (trade name TO-A2) was cut into 100mm × 100mm pieces and vacuum dried at 23°C for 8 hours. The initial weight was measured. Next, the film was stored at 23°C and 55% relative humidity for 2 weeks, and the weight after storage was measured. The water absorption capacity of the moisture absorber (R) was calculated using the following formula.

[0306] Water absorption rate [g / m] 2 = (Saved weight - Initial weight) × 100

[0307] The water absorption of the moisture-absorbing layer monomers of the moisture-absorbing agent (R) is calculated by subtracting the water absorption of each monomer in the layers other than the moisture-absorbing layer of the moisture-absorbing agent (R), namely the PET film (PET1) and the impermeable layer (AL1).

[0308] (Determination of peel strength)

[0309] • Peel force between the surface protective film (adhesive layer A) and the TAC of the polarizing plate

[0310] A laminate containing laminate B (PET film (PET2) / adhesive layer A) / polarizer A / adhesive layer (thickness 25 μm) was prepared. The laminate was cut into 25 mm × 120 mm pieces. After the adhesive layer was bonded to the glass, it was subjected to autoclave treatment at 50 °C and 0.49 MPa to obtain test pieces for peel strength evaluation.

[0311] After storing the test piece for peel strength evaluation at 23°C and 60% relative humidity for 24 hours, the PET film and adhesive layer A were peeled from the TAC of polarizing plate A using Autograph (manufactured by Shimadzu Corporation, trade name "AGS-X (50N)") at a peel angle of 180° and a peel speed of 300 mm / min. The test force during peeling was averaged within the peeling range to obtain the peel strength between the surface protective film (adhesive layer A) and the polarizing plate.

[0312] • Peel force between adhesive layer α (adhesive layer B) and the TAC of the polarizing plate

[0313] Prepare a laminate containing PET film (PET3) / adhesive layer B / polarizer A / adhesive layer (thickness 25μm). Otherwise, in the same manner as the peel force of adhesive layer A and the TAC of polarizer A, peel the PET film and adhesive layer B from the TAC of polarizer A to obtain the peel force of adhesive layer α (adhesive layer B) to polarizer.

[0314] • Peel force between adhesive layer α (adhesive layer B) and the separator (PET3)

[0315] Prepare a PET film (PET3) measuring 25mm × 120mm. After laminating the PET3 onto glass via adhesive layer B, it is subjected to autoclave treatment at 50°C and 0.49MPa to obtain a test piece for peel strength evaluation. In this test piece, the release surface of the PET3 is positioned so that the adhesive layer B side is the release treatment side.

[0316] After storing the test piece used for peel force evaluation at 23°C and 60% relative humidity for 24 hours, the PET film was peeled from the adhesive layer B using an Autograph (manufactured by Shimadzu Corporation, trade name "AGS-X (50N)") at a peel angle of 180° and a peel speed of 300 mm / min. The test force during peeling was averaged within the peeling range to obtain the peel force between the adhesive layer α (adhesive layer B) and the separator.

[0317] The results of the measurements show that, in the embodiments, the peel force when peeling the surface protective film from the polarizing plate is greater than the peel force when peeling the separator from the adhesive layer. Furthermore, the peel force when peeling the surface protective film from the polarizing plate is less than the peel force when peeling the polarizing plate from the adhesive α.

[0318] (Initial determination of Ty, Py and monomer b values)

[0319] For the durability evaluation samples obtained in each embodiment and comparative example, the MD transmittance and TD transmittance in the wavelength range of 380–780 nm were measured using a spectrophotometer with an integrating sphere (manufactured by Nippon Spectrophotometer Co., Ltd., trade name: V7100). Then, the monomer transmittance and degree of polarization at each wavelength were calculated based on the following formula.

[0320] Monomer transmittance (%) = (MD transmittance + TD transmittance) / 2

[0321] Degree of polarization (%) = {(MD transmittance - TD transmittance) / (MD transmittance + TD transmittance)} × 100.

[0322] Here, MD transmittance refers to the transmittance when the direction of polarized light emitted from the Gran Thompson prism is parallel to the transmission axis of the durability evaluation sample. TD transmittance refers to the transmittance when the direction of polarized light emitted from the Gran Thompson prism is orthogonal to the transmission axis of the durability evaluation sample. The obtained monomer transmittance and degree of polarization are determined according to JIS Z 8701:1999 "Methods for representing colors - XYZ color system and X..." 10 Y 10 Z 10 Visibility correction was performed on a 2-degree field of view (C light source) of the "color system" to calculate the visibility-corrected single-cell transmittance (Ty), visibility-corrected polarization degree (Py), and single-cell b value. These were used as the initial Ty, Py, and single-cell b values. The results are shown in Table 2.

[0323] (Determination of Ty and Py after high-temperature durability test)

[0324] The samples used for durability evaluation were stored at a heating environment of 105°C for 500 hours to conduct a high-temperature durability test. For the samples after the high-temperature durability test, the monomer transmittance and polarization degree were measured using the same method as described above, and Ty and Py were calculated. Based on the obtained Ty and Py values ​​after the high-temperature durability test, the suppression effect of transmittance and polarization degree reduction under high-temperature conditions was evaluated according to the following criteria. The results are shown in Table 2.

[0325] It should be noted that the following criteria are used to determine yellowing.

[0326] A: Ty > 36%

[0327] B: 36% ≥ Ty > 28%

[0328] C: 28% ≥ Ty > 15%

[0329] D: 15% ≥ Ty > 5%

[0330] E: Ty≤5%

[0331] [Table 2]

[0332]

[0333] [Table 3]

[0334]

[0335] Explanation of reference numerals in the attached figures

[0336] 100… Surface protective film, 140, 630… Moisture-absorbing layer, 150, 640… Impermeable layer, 200… Polarizing plate, 210… PVA-based polarizing film, 220… First protective layer, 230… Second protective layer, 500… Adhesive layer α, 600… Separator, 1000… Optical laminate.

Claims

1. An optical laminate, comprising sequentially a surface protective film, a first protective layer, a PVA-based polarizer, a second protective layer, an adhesive layer α, and a separator, At least one of the surface protective film and the separator has a moisture-impermeable layer and a moisture-absorbing layer disposed closer to the PVA-based polarizer than the moisture-impermeable layer.

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

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

4. The optical laminate according to claim 3, wherein, The diaphragm also includes a moisture-absorbing layer, which is positioned closer to the PVA-based polarizer than the impermeable layer.

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

6. The optical laminate according to claim 1, wherein, The diaphragm has the moisture-impermeable layer and the moisture-absorbing layer. 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 of the following is selected from the PVA-based polarizer, the adhesive layer between the first protective layer and the PVA-based polarizer, the adhesive layer between the second protective layer and the PVA-based polarizer, and the adhesive layer α, comprising at least one selected from urea compounds, amide compounds, and hindered amine compounds.

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