Adhesive film for polarizing plate, polarizing plate, and display device

Abstract

To provide an adhesive film for a polarizing plate that has superior adhesion to a substrate.SOLUTION: An adhesive film for a polarizing plate includes a cured product of a composition containing a copolymer of a monomer mixture including an unsaturated monomer having an alkyl group, an unsaturated monomer having a hydroxyl group, and an unsaturated monomer having an amide group and a long-chain alkylene group or a long-chain alkyl group, and a curing agent. The adhesive film for a polarizing plate may have a substrate adhesion of 1.10 kgf / 25 mm or more to a substrate having a water contact angle of 70° or more. The substrate may be a liquid crystal layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an adhesive film for a polarizing plate, a polarizing plate, and a display device including the polarizing plate. [Background technology]

[0002] Light-emitting display devices, including organic light-emitting display devices, may not include a polarizer. However, incident external light may be totally reflected by the panel in the light-emitting display device, degrading the image quality. For this reason, light-emitting display devices generally include a polarizer on the upper surface of the panel. The polarizer is composed of a polarizer and a retardation film. The retardation film may be a polymer film, but in recent years, liquid crystal films have been used in line with the trend toward thinner displays.

[0003] A liquid crystal film can be produced by forming an alignment layer on a substrate film, coating the substrate with a liquid crystal layer composition, and curing the coating. The substrate film can be left on the polarizing plate to function as a protective layer, but is generally removed. After the substrate film is removed, the alignment layer is exposed. Therefore, it is preferable that the adhesive film used in the polarizing plate has excellent adhesion to both hydrophilic and hydrophobic surfaces.

[0004] In recent years, interest in flexible display devices has been increasing rapidly, and therefore, polarizing plates used in such display devices are also required to have excellent flexibility.

[0005] The background art of the present invention is disclosed in, for example, Patent Document 1. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Korean Patent Publication No. 2015-0010567 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide an adhesive film for polarizing plates that has excellent adhesion to a substrate.

[0008] Another object of the present invention is to provide an adhesive film for polarizing plates that can adhere with high adhesive strength to a liquid crystal retardation layer having a high surface water contact angle without surface treatment.

[0009] A further object of the present invention is to provide an adhesive film for polarizing plates that has excellent heat resistance reliability and moist heat resistance reliability when applied to a flat surface.

[0010] A further object of the present invention is to provide an adhesive film for polarizing plates that has excellent heat resistance reliability and moist heat resistance reliability even on curved surfaces. [Means for solving the problem]

[0011] According to one embodiment, there is provided an adhesive film for a polarizing plate.

[0012] The adhesive film for polarizing plates comprises a cured product of a composition comprising a copolymer of a monomer mixture containing an alkyl group-containing unsaturated monomer, a hydroxyl group-containing unsaturated monomer, and an unsaturated monomer having an amide group and a long-chain alkylene group or a long-chain alkyl group, and a curing agent.

[0013] According to one embodiment, a polarizer is provided.

[0014] The polarizing plate includes the above-mentioned pressure-sensitive adhesive film for polarizing plates.

[0015] According to one embodiment, a display device is provided.

[0016] A display device includes the polarizing plate. [Effects of the Invention]

[0017] The pressure-sensitive adhesive film for polarizing plates of the present invention has excellent adhesion to the substrate, and can prevent peeling from the substrate.

[0018] The pressure-sensitive adhesive film for polarizing plates of the present invention can adhere with high adhesive strength to a liquid crystal retardation layer having a high surface water contact angle without surface treatment of the liquid crystal retardation layer, thereby improving processability.

[0019] The pressure-sensitive adhesive film for polarizing plates of the present invention has excellent heat resistance reliability and moist heat resistance reliability on both flat and curved surfaces, and is applicable to non-flexible and flexible display devices, providing excellent reliability. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a cross-sectional view of a polarizing plate according to one embodiment of the present invention. [Figure 2] FIG. 10 is a cross-sectional view of a polarizing plate according to another embodiment of the present invention. [Figure 3] FIG. 10 is a cross-sectional view of a polarizing plate according to still another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] The present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. The present invention may be implemented in various different forms and is not limited to the embodiments described herein. In the drawings, parts that are not relevant to the description are omitted to clearly explain the present invention, and the same reference numerals are used throughout the specification to refer to the same or similar components. In the drawings, the length, thickness, etc. of each component are shown for the purpose of explaining the present invention, and the present invention is not limited to the length, thickness, etc. shown in the drawings.

[0022] The terms used herein are merely for the purpose of describing exemplary embodiments and are not intended to limit the present invention. The singular expressions include the plural expressions unless the context clearly dictates otherwise.

[0023] In this specification, "upper" and "lower" are based on the drawings and are not necessarily fixed to the upper and lower parts. Depending on the viewing angle, "upper" may be changed to "lower" and "lower" may be changed to "upper".

[0024] In this specification, the "in-plane retardation (Re)" is represented by the following formula A.

[0025] [Formula A] Re = (nx - ny) × d

[0026] In Formula A, nx and ny are the refractive indices in the slow axis direction and the fast axis direction of the optical element at the measurement wavelength, respectively, and d is the thickness of the optical element (unit: nm).

[0027] In this specification, "inverse wavelength dispersion" means that Re(450) < Re(550) < Re(650).

[0028] In this specification, "(meth)acryl" means acrylic and / or methacrylic.

[0029] In this specification, the "glass transition temperature of the homopolymer" may be the glass transition temperature (Tg) measured using TA Instrument's DSC Discovery for the homopolymer of the monomer to be measured. Specifically, after raising the temperature of the homopolymer of the monomer to be measured to 180°C at a rate of 20°C / min, cooling it to -100°C while gradually cooling, and then heating it to 100°C at a rate of 10°C / min, an endothermic transition curve can be obtained as data, and the inflection point of the endothermic transition curve can be determined as the glass transition temperature.

[0030] In this specification, when describing a numerical range, "X to Y" means X or more and Y or less (X~Y).

[0031] The pressure-sensitive adhesive film for polarizing plates according to one embodiment can provide excellent adhesion to the substrate.

[0032] Here, the "substrate" can include a hydrophilic substrate and a hydrophobic substrate. That is, the adhesive film for a polarizing plate has excellent adhesion to both the hydrophilic substrate and the hydrophobic substrate. According to one embodiment, in a laminated structure of hydrophilic substrate-adhesive film for a polarizing plate-hydrophobic substrate, the adhesive film for a polarizing plate has excellent adhesion to both the hydrophilic substrate and the hydrophobic substrate, thereby preventing peeling between the hydrophilic substrate and the hydrophobic substrate and improving durability and reliability.

[0033] In an embodiment, the hydrophilic substrate may be a polarizer, a hydrophilic protective layer, a hydrophilic protective film, a hydrophilic retardation layer, a hydrophilic retardation film, or a hydrophilic alignment film.

[0034] In one embodiment, the hydrophobic substrate may be a hydrophobic protective layer, a hydrophobic protective film, a hydrophobic retardation layer, a hydrophobic retardation film, or a hydrophobic alignment film.

[0035] In one embodiment, the adhesive film for polarizing plates may have a substrate adhesion strength of 1.10 kgf / 25 mm or more, for example, 1.10 kgf / 25 mm to 3.0 kgf / 25 mm, to a liquid crystal retardation layer having a water contact angle of 70° or more, for example, 80° to 90°. Within this range, no delamination occurs, and the film has excellent reliability on both flat and curved surfaces.

[0036] The pressure-sensitive adhesive film for polarizing plates according to one embodiment can adhere with high adhesion to a liquid crystal retardation layer having a high surface water contact angle without surface treatment of the liquid crystal retardation layer, thereby improving processability. Specifically, the liquid crystal retardation layer may have a water contact angle of 70° or more, for example, 80° to 90°. In order for a conventional pressure-sensitive adhesive film for polarizing plates to be bonded with high adhesion to a liquid crystal retardation layer, surface treatment (e.g., corona treatment) of the liquid crystal retardation layer is required. However, the pressure-sensitive adhesive film for polarizing plates according to one embodiment can adhere with high adhesion to a liquid crystal retardation layer without surface treatment of the liquid crystal retardation layer. Here, the "water contact angle" is a value measured at 25°C and can be measured using a conventional method known to those skilled in the art.

[0037] The adhesive film for polarizers according to an embodiment has excellent heat resistance and humidity resistance reliability on both flat and curved surfaces, and therefore can be applied to non-flexible and flexible display devices to provide excellent reliability.

[0038] According to one embodiment, the pressure-sensitive adhesive film for polarizing plates includes a cured product of a composition including a copolymer of a monomer mixture including an alkyl group-containing unsaturated monomer, a hydroxyl group-containing unsaturated monomer, and an unsaturated monomer having an amide group and a long-chain alkylene group or a long-chain alkyl group, and a curing agent. By using the unsaturated monomer having an amide group and a long-chain alkylene group or a long-chain alkyl group, the pressure-sensitive adhesive film for polarizing plates can provide high adhesion to the above-mentioned substrate, and excellent heat resistance and humidity and heat resistance reliability on both flat and curved surfaces.

[0039] The PSA film may have a haze of 1% or less, specifically 0% to 1%, in the visible light region, for example, at a wavelength of 550 nm. If the haze is within the above range, the PSA film can be used in a display device.

[0040] The adhesive film may have a thickness of 5 μm to 50 μm, specifically 5 μm to 35 μm. If the thickness is within this range, the adhesive film can be used for a polarizing plate.

[0041] The adhesive film for polarizing plates can be used to adhere a polarizer to a liquid crystal retardation layer, to adhere a protective layer of a polarizer to a liquid crystal retardation layer, or to adhere liquid crystal retardation layers to each other.

[0042] Hereinafter, an adhesive film for polarizing plates according to one embodiment will be described.

[0043] The pressure-sensitive adhesive film for polarizing plates contains a cured product of the composition.

[0044] In one embodiment, the pressure-sensitive adhesive film for polarizing plates may be a thermoset product.

[0045] In one embodiment, the pressure-sensitive adhesive film for polarizing plates can include a copolymer containing an alkyl group-containing unsaturated monomer, a hydroxyl group-containing unsaturated monomer, and an unsaturated monomer having an amide group and a long-chain alkylene group or a long-chain alkyl group, and a curing agent. These can be derived from the above-mentioned composition.

[0046] <Copolymer> Copolymers include copolymers of a monomer mixture containing an alkyl group-containing unsaturated monomer, a hydroxyl group-containing unsaturated monomer, and an unsaturated monomer having an amide group and a long-chain alkylene group or a long-chain alkyl group.

[0047] In one embodiment, the total content of the alkyl group-containing unsaturated monomer, the hydroxyl group-containing unsaturated monomer, and the unsaturated monomer having an amide group and a long-chain alkylene group or a long-chain alkyl group in the monomer mixture may be 95% by weight or more, for example, 99% by weight to 100% by weight, or 100% by weight. If the content is within the above range, it may be easy to provide the effects of an adhesive film.

[0048] In one embodiment, the copolymer may be a (meth)acrylic copolymer.

[0049] The alkyl group-containing unsaturated monomer may include a (meth)acrylic monomer having an alkyl group.

[0050] The (meth)acrylic monomer having an alkyl group may be a (meth)acrylic monomer having an alkyl group at the ester moiety. Here, the "alkyl group" may be a linear or branched alkyl group having 1 to 10 carbon atoms. Specifically, the alkyl group-containing (meth)acrylic monomer may include, but is not limited to, one or more of ethyl acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, iso-octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, and dodecyl (meth)acrylate.

[0051] The (meth)acrylic monomer having an alkyl group may have a homopolymer glass transition temperature of less than 0° C., for example, −80° C. to −10° C., or −70° C. to −10° C. If the glass transition temperature is within the above range, it may be easy to provide an effect of improving the processability and reliability of the polarizing plate according to an embodiment.

[0052] The alkyl group-containing (meth)acrylic monomer may be contained in the monomer mixture in an amount of 60 to 95% by weight, for example, 80 to 95% by weight, or 85 to 95% by weight, which may facilitate the improvement of peel strength and reliability of the polarizing plate.

[0053] The hydroxyl group-containing unsaturated monomer may include a (meth)acrylic monomer having a hydroxyl group.

[0054] The (meth)acrylic monomer having a hydroxyl group can include one or more of a (meth)acrylic monomer having an alkyl group having 1 to 20 carbon atoms and a hydroxyl group, a (meth)acrylic monomer having a cycloalkyl group having 3 to 20 carbon atoms and a hydroxyl group, and a (meth)acrylic monomer having an aromatic group having 6 to 20 carbon atoms and a hydroxyl group. Specifically, the (meth)acrylic monomer having a hydroxyl group is a (meth)acrylic acid ester having an alkyl group having 1 to 20 carbon atoms and a hydroxyl group, and can include one or more of 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate. These can be used alone or in combination.

[0055] The unsaturated monomer having a hydroxyl group may be contained in the monomer mixture in an amount of 0.1 to 10% by weight, specifically 0.1 to 5% by weight, specifically 0.1 to 3% by weight. Within this range, the peel strength of the PSA film can be ensured and the glass transition temperature can be easily adjusted.

[0056] The unsaturated monomer having an amide group and a long-chain alkylene group or a long-chain alkyl group has an amide group and a long-chain alkylene group or a long-chain alkyl group within the monomer. The amide group is hydrophilic, while the long-chain alkylene group or the long-chain alkyl group is hydrophobic. Therefore, the unsaturated monomer has excellent substrate adhesion to both hydrophilic and hydrophobic substrates.

[0057] Here, the long-chain alkylene group may be a linear or branched alkylene group having 8 to 20 carbon atoms, and preferably an alkylene group having 15 to 20 carbon atoms.

[0058] Here, the long-chain alkyl group may be a linear or branched alkyl group having 8 to 20 carbon atoms, and preferably an alkyl group having 15 to 20 carbon atoms.

[0059] In one embodiment, the unsaturated monomer may be represented by Formula 1 below:

[0060] [Chemical formula 1] [ka]

[0061] In Chemical Formula 1, R is hydrogen or an alkyl group having 1 to 5 carbon atoms; L 11 is a linear or branched alkylene group having 1 to 10 carbon atoms, L 12 is a linear or branched alkyl group having 8 to 20 carbon atoms.

[0062] In one embodiment, L in Formula 1 11 is a linear or branched alkylene group having 1 to 5 carbon atoms, and L 12 may be a linear or branched alkyl group having 10 to 20 carbon atoms, or 15 to 20 carbon atoms.

[0063] The unsaturated monomer may be contained in the monomer mixture in an amount of 1 to 30% by weight. This range ensures the adhesive strength of the PSA film and facilitates the control of the glass transition temperature. Specifically, the unsaturated monomer may be contained in the monomer mixture in an amount of 5 to 20% by weight. This range further improves the adhesive strength to the substrate, and further improves the heat resistance reliability and moist heat resistance reliability on flat and curved surfaces.

[0064] The copolymer may have a weight-average molecular weight (Mw) of 1,000,000 to 2,000,000 g / mol, for example, 1,500,000 to 2,000,000 g / mol. Within this range, the effects of the present invention can be easily achieved. Here, the "weight-average molecular weight" may be measured in terms of polystyrene using gel permeation chromatography.

[0065] The copolymer may have a glass transition temperature (Tg) of −35° C. or lower, for example, −35° C. to −10° C. Within this range, the effects of the present invention can be easily achieved. Here, the “glass transition temperature” may be measured using a differential scanning calorimeter (DSC).

[0066] In one embodiment, the copolymer may be produced by polymerizing a monomer mixture using a conventional polymerization method. The polymerization method may include conventional methods known to those skilled in the art. For example, a (meth)acrylic copolymer may be produced by adding an initiator to a monomer mixture and then performing conventional copolymer polymerization, such as suspension polymerization, emulsion polymerization, or solution polymerization. The polymerization temperature may be 65°C to 70°C, and the polymerization time may be 6 to 8 hours. Conventional initiators, including azo polymerization initiators and / or peroxides such as benzoyl peroxide or acetyl peroxide, may be used.

[0067] <Curing agent> The curing agent is a thermosetting curing agent and may include one or more of an isocyanate-based curing agent, an epoxy-based curing agent, an amine-based curing agent, a metal chelate-based curing agent, and an aziridine-based curing agent. Preferably, the curing agent includes an isocyanate-based curing agent.

[0068] The isocyanate curing agent may be a bifunctional to hexafunctional isocyanate curing agent. Specifically, the isocyanate curing agent may include one or more aromatic isocyanate curing agents selected from toluene diisocyanate, xylylene diisocyanate, halogen-substituted toluene diisocyanate, phenylene diisocyanate (e.g., m-phenylene diisocyanate), and tetramethyl-xylylene diisocyanate, one or more aliphatic isocyanate curing agents selected from hexamethylene diisocyanate and pentamethylene diisocyanate, alicyclic isocyanate curing agents such as cyclohexamethylene diisocyanate, or adducts thereof, for example, one or more adducts of a polyol such as trimethylolpropane (TMP) and the above-mentioned curing agents.

[0069] The curing agent, for example, an isocyanate-based curing agent, may be included in an amount of 0.05 to 2 parts by weight, for example, 0.25 to 1 part by weight, based on 100 parts by weight of the copolymer. Within this range, excellent adhesive strength and reliability can be achieved.

[0070] The composition may further contain a silane coupling agent, which can further increase the peel strength of the pressure-sensitive adhesive film for polarizing plates.

[0071] The silane coupling agent may be included in an amount of 0.001 to 5 parts by weight per 100 parts by weight of the copolymer. This range can provide an improved release force. Preferably, the silane coupling agent may be included in an amount of 0.01 to 1 part by weight.

[0072] The silane coupling agent can include one or more of an epoxy group-containing silane coupling agent, a mercapto group-containing silane coupling agent, an amine group-containing silane coupling agent, an alkyl group-containing silane coupling agent, and an isocyanate group-containing silane coupling agent.

[0073] Preferably, the silane coupling agent may include an amino group-containing silane coupling agent. The epoxy group-containing silane coupling agent can promote the development of the effects of the present invention. Specifically, as the amino group-containing silane coupling agent, an epoxy group-containing silane coupling agent such as glycidoxypropyltrimethoxysilane, glycidoxypropylmethyldimethoxysilane, or epoxycyclohexylpropyltrimethoxysilane can be used.

[0074] The composition may further contain conventional additives known to those skilled in the art, including, but not limited to, ultraviolet absorbers, antioxidants, surfactants, pigments, dyes, heat stabilizers, dispersants, inorganic particles, etc.

[0075] The composition may be a solvent-free type that does not contain a solvent, but the composition may contain a solvent to improve its applicability.

[0076] The adhesive film may be manufactured using the composition by conventional methods known to those skilled in the art.

[0077] A polarizing plate according to one embodiment includes an adhesive film for polarizing plates.

[0078] The polarizing plate includes a polarizer and an adhesive film for polarizing plates laminated on at least one surface of the polarizer.

[0079] The adhesive film for polarizing plates has been described above, and therefore its description will be omitted.

[0080] <Polarizer> A polarizer can polarize external or internal light.

[0081] The polarizer may include a polyvinyl alcohol-based polarizer obtained by dyeing a polyvinyl alcohol-based film with iodine or the like. For example, a polyvinyl alcohol-based polarizer is manufactured by dyeing a polyvinyl alcohol film with iodine or a dichroic dye and stretching the dye in a specific direction. Specifically, the polarizer is manufactured through a swelling process, a dyeing step, and a stretching step. Methods for performing each step are generally known to those skilled in the art.

[0082] The polarizer may have a thickness of 1 μm to 50 μm. If the thickness is within this range, the polarizer can be used in a display device.

[0083] The polarizing plate may further include a retardation layer on at least one surface of the polarizer.

[0084] <Retardation layer> The retardation layer prevents reflection of external light by circularly polarizing the linearly polarized light emitted after the external light passes through the polarizer, and by having an anti-reflection function, it is possible to improve the appearance and the screen quality.

[0085] In one embodiment, the retardation layer has a retardation in the in-plane direction at a wavelength of 550 nm of 100 nm to 220 nm, specifically 100 nm to 180 nm, for example, a retardation of λ / 4 (first retardation layer).Within this range, the reflectance to external light can be reduced, and the screen quality can be improved.

[0086] In another specific example, the retardation layer has a retardation in the in-plane direction at a wavelength of 550 nm of 225 nm to 350 nm, specifically 225 nm to 300 nm, for example, a retardation of λ / 2 (second retardation layer).Within the above range, the reflectance to external light can be reduced, and the screen quality can be improved.

[0087] In yet another specific example, the retardation layer may be a laminate of a first retardation layer and a second retardation layer.

[0088] In one embodiment, the retardation layer can exhibit reverse wavelength dispersion.

[0089] In one embodiment, the retardation layer may have a thickness of 0.1 μm to 10 μm, for example, 1 μm to 5 μm. Within this range, the polarizing plate can be made thinner and a target retardation can be achieved.

[0090] In one embodiment, the retardation layer may be a non-liquid crystal layer or a liquid crystal layer. Preferably, the retardation layer is a liquid crystal layer, which allows the polarizing plate to be made thinner.

[0091] For example, the liquid crystal retardation layer may be formed of a composition containing a liquid crystal compound having one or more of an aromatic functional group and an alicyclic functional group. In one embodiment, the liquid crystal compound may be a polymer, oligomer, or monomer containing a unit composed of an aromatic ring and a polymerizable functional group that can impart liquid crystallinity. The polymerizable functional group may be a (meth)acryloyl group, an epoxy group, a vinyl ether group, or the like, and may be cured by heat or light, thereby increasing the strength of the liquid crystal retardation layer.

[0092] In one embodiment, the liquid crystal retardation layer may have a water contact angle of 70° or more, for example, 80° to 90°.

[0093] The composition may be formed from a composition containing the aromatic-containing liquid crystal compound described above. The composition may further contain additives such as a leveling agent, a polymerization initiator, an alignment aid, a heat stabilizer, a lubricant, a plasticizer, and an antistatic agent, and the details of these additives may be found in those known to those skilled in the art.

[0094] The polarizing plate may further include a protective layer on at least one surface of the polarizer.

[0095] <Protective layer> A protective layer is formed on at least one surface of the polarizer to protect the polarizer or to provide an additional function to the polarizing plate.

[0096] The protective layer may include one or more of an optically clear protective film and a protective coating layer.

[0097] When the protective layer is a protective film type, it may include a protective film formed of an optically transparent resin. The protective film may be formed by melting and extruding the resin. If necessary, a stretching process may be further added. The resin may include one or more of cellulose ester-based resins including triacetyl cellulose, cyclic polyolefin-based resins including cyclic olefin polymers (COP), polycarbonate-based resins, polyester-based resins including polyethylene terephthalate (PET), polyethersulfone-based resins, polysulfone-based resins, polyamide-based resins, polyimide-based resins, acyclic polyolefin-based resins, polyacrylate-based resins including polymethyl methacrylate resin, polyvinyl alcohol-based resins, polyvinyl chloride-based resins, and polyvinylidene chloride-based resins. Preferably, the protective film may be a film formed of a cyclic polyolefin-based resin including a cyclic polyolefin.

[0098] When the protective layer is a protective coating layer type, it can improve adhesion to the polarizer, transparency, mechanical strength, thermal stability, moisture blocking ability, and durability. In one embodiment, the protective coating layer for the protective layer may be formed of an active energy ray-curable resin composition including an active energy ray-curable compound and a polymerization initiator.

[0099] The active energy ray-curable compound may include one or more of a cationically polymerizable curable compound, a radically polymerizable curable compound, a urethane resin, and a silicone resin. The cationically polymerizable curable compound may be an epoxy-based compound having at least one epoxy group in the molecule, or an oxetane-based compound having at least one oxetane ring in the molecule. The radically polymerizable curable compound may be a (meth)acrylic-based compound having at least one (meth)acryloyloxy group in the molecule.

[0100] The thickness of the protective layer is 5 μm to 200 μm, specifically 30 μm to 120 μm, and may be 50 μm to 100 μm in the case of a protective film type, or 5 μm to 50 μm in the case of a protective coating layer type. If the thickness is within the above range, the protective layer can be used in an optical display device.

[0101] The protective layer may include a functional coating layer formed on at least one surface thereof or may be surface-treated. The functional coating layer may be, but is not limited to, a hard coating layer, an anti-fingerprint layer, an anti-reflection layer, a low-reflection layer, an ultra-low-reflection layer, an anti-glare layer, etc. The surface treatment may be, but is not limited to, a corona treatment.

[0102] The protective layer may be bonded to a polarizer or an adherend other than a polarizer by an adhesive layer. The adhesive layer may be formed of, but is not limited to, a water-based adhesive or a photocurable adhesive. The water-based adhesive and the photocurable adhesive may be used as appropriate, taking into account the details known to those skilled in the art.

[0103] The polarizing plate may include one or more adhesive layers, and the polarizing plate may include one or more adhesive layers, or two or more adhesive layers.

[0104] <Adhesive layer> The adhesive layer can adhere the barrier layer to the retardation layer or the barrier layer to the protective layer.

[0105] In one embodiment, the adhesive layer may be a pressure sensitive adhesive (PSA). For example, the pressure sensitive adhesive may include a cured product of a composition including an adhesive resin and a curing agent.

[0106] 1 to 3 are cross-sectional views of a polarizing plate according to an embodiment.

[0107] Referring to FIG. 1, the polarizing plate may include a polarizer 100, a protective layer 200 laminated on the upper surface of the polarizer 100, a first polarizing plate adhesive film 300 sequentially laminated on the lower surface of the polarizer, and a first retardation layer 400.

[0108] Referring to FIG. 2, the polarizing plate may include a polarizer 100, a protective layer 200 laminated on the upper surface of the polarizer, a first polarizing plate adhesive film 300, a second retardation layer 500, a second polarizing plate adhesive film 600, and a first retardation layer 400 sequentially laminated on the lower surface of the polarizer 100.

[0109] Referring to FIG. 3, the polarizing plate may include a polarizer 100, a protective layer 200 laminated on the upper surface of the polarizer, an adhesive film 300 for a first polarizing plate, a second retardation layer 500, an adhesive film 600 for a second polarizing plate, a first retardation layer 400, and an adhesive film 700 for a third polarizing plate, which are sequentially laminated on the lower surface of the polarizer.

[0110] At least one of the first adhesive film for polarizer 300 and the second adhesive film for polarizer 600 may be the adhesive film for polarizer of the above-mentioned embodiment. The first adhesive film for polarizer 300 and the second adhesive film for polarizer 600 may be manufactured using the same adhesive film composition for polarizer.

[0111] The third adhesive film 700 for a polarizing plate may be the adhesive film for a polarizing plate of the embodiment described above, or may be a commonly known adhesive film.

[0112] Although not shown in FIGS. 1 to 3, the polarizing plate may further include one or more of a polarizer protective film, an anti-reflection film, a retardation film (liquid crystal layer or non-liquid crystal layer), and an adhesive film, which are commonly used in polarizing plates.

[0113] An optical display device according to one embodiment of the present invention includes the polarizing plate of the present invention. For example, the optical display device may be a light-emitting device display device including a light-emitting element, a liquid crystal display device, or the like. [Example]

[0114] The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to these examples.

[0115] <Production Example: Production of a Monomer Having an Amide Group and a Long-Chain Alkyl Group> The monomer having an amide group and a long-chain alkyl group was prepared according to the following reaction scheme.

[0116] N-(3-hydroxypropyl)heptadecanamide (200 g), methacrylic anhydride (98 g), and 4-(dimethylamino)pyridine (DMAP, 0.73 g) were reacted at 60°C for 24 hours. After adding 10 mL of distilled water and reacting for 1 hour, the mixture was extracted with dichloromethane to obtain N-(methacryloyloxy)propyl heptadecanamide (MPHA).

[0117] [Reaction scheme] [ka]

[0118] Example 1 (1) Manufacturing of adhesive film for polarizing plates (first adhesive film = second adhesive film) A monomer mixture was prepared by mixing 89 parts by weight of n-butyl acrylate (n-BA), 1 part by weight of 4-hydroxybutyl acrylate (4-HBA), and 10 parts by weight of the monomer MPHA prepared in the above Preparation Example. The prepared monomer mixture was placed in a 1 L reactor equipped with a nitrogen gas reflux and a cooling device for easy temperature control, and 10 parts by weight of ethyl acetate was added as a solvent. Nitrogen gas was then introduced for 1 hour to purge the interior of the reactor, and the internal temperature of the reactor was maintained at 65°C. After uniformly stirring the monomer mixture, 0.03 parts by weight of azobisisobutyronitrile as a reaction initiator was added and the mixture was allowed to react for 8 hours to produce an acrylic copolymer (Mw: 1.57 million g / mol).

[0119] Based on the solid content, 0.5 parts by weight of Coronate L (an isocyanate-based curing agent, Polyurethanes Co., Ltd.) as a curing agent and 0.1 parts by weight of KBM-403 (Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent were added to 100 parts by weight of the prepared acrylic copolymer, and ethyl acetate was added to make the solid content concentration 20% by weight to prepare a composition for adhesive film.

[0120] The adhesive film composition thus prepared was applied to a PET release film at a predetermined thickness, dried, and then heated (baked) at 100°C for 4 minutes to prepare an adhesive film for a polarizing plate (thickness: 10 μm). The adhesive films thus prepared were used as the first adhesive film and the second adhesive film, respectively.

[0121] (2) Manufacturing of adhesive film for polarizing plates (third adhesive film) A monomer mixture was prepared by mixing 94 parts by weight of n-butyl acrylate (n-BA), 1 part by weight of 4-hydroxybutyl acrylate (4-HBA), and 5 parts by weight of acrylic acid. The prepared monomer mixture was placed in a 1 L reactor equipped with a nitrogen gas reflux and a cooling device for easy temperature control, and 10 parts by weight of ethyl acetate was added as a solvent. Nitrogen gas was then introduced for 1 hour to purge the interior of the reactor, and the internal temperature of the reactor was maintained at 65°C. After uniformly stirring the monomer mixture, 0.03 parts by weight of azobisisobutyronitrile was added as a reaction initiator and reacted for 8 hours to produce an acrylic copolymer (Mw: 1.68 million g / mol).

[0122] Based on the solid content, 0.5 parts by weight of Coronate L (an isocyanate-based curing agent, Polyurethanes Co., Ltd.) as a curing agent and 0.1 parts by weight of KBM-403 (Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent were added to 100 parts by weight of the prepared acrylic copolymer, and ethyl acetate was added to make the solid content concentration 20% by weight to prepare a composition for adhesive film.

[0123] The adhesive film composition thus prepared was applied to a PET release film at a predetermined thickness, dried, and then heated (baked) at 100°C for 4 minutes to prepare an adhesive film for a polarizing plate (thickness: 25 μm). The adhesive film thus prepared was used as the third adhesive film.

[0124] (3) Manufacture of polarizing plates A polyvinyl alcohol film (Mitsubishi Chemical Corporation, degree of polymerization: 2800, thickness: 20 μm) was dyed by immersing it in a 0.3% potassium iodide aqueous solution, and then stretched in the machine direction (MD) at a uniaxial stretching ratio of 5.0. The stretched polyvinyl alcohol film was then immersed in a 3% boric acid aqueous solution and a 2% potassium iodide aqueous solution to correct the hue, and dried at 50°C for 4 minutes to produce a polarizer (light transmittance: 45%, thickness: 7 μm).

[0125] A cyclic olefin polymer film (thickness: 25 μm, Zeon) with a hard coating layer formed on its upper surface was prepared as an upper polarizer protective film, and the lower surface of the film was subjected to corona treatment using a corona treatment device (AFS) at a speed of 10 mpm and an output of 1000 W.

[0126] As a lower polarizer protective film, a triacetyl cellulose film (thickness: 40 μm, Konica Corporation, normal TAC) was prepared without saponification treatment.

[0127] A polyvinyl alcohol resin (Z200, average degree of polymerization: 1200, degree of saponification: 98.5 mol%, contains acetoacetyl groups; degree of acetoacetylation: 5 mol%, Mitsubishi Chemical Corporation) was dissolved in water at 95°C for 60 minutes and then cooled completely to room temperature to produce a polyvinyl alcohol resin aqueous solution. Then, a water-based adhesive was produced by adding and mixing 0.1 parts by weight of a zirconium-containing crosslinker, Zircosol-ZN (Daiichi Kigenso Kagaku Kogyo Co., Ltd.), per 100 parts by weight of the produced polyvinyl alcohol resin aqueous solution.

[0128] The prepared aqueous adhesive was applied to both sides of the manufactured polarizer in a predetermined thickness, and an upper polarizer protective film was simultaneously attached to one side and a lower polarizer protective film to the other side. After drying at 80°C for 3 minutes, the triacetyl cellulose-based film was removed to expose the other side of the polarizer.

[0129] A λ / 2 liquid crystal retardation film (Fujifilm Corporation, hydrophobic, water contact angle 86° at 25°C, laminate of a λ / 2 liquid crystal retardation layer (thickness: 2 μm) and a substrate film) was prepared. The λ / 2 liquid crystal retardation layer side of the λ / 2 liquid crystal retardation film was not surface-treated with corona.

[0130] The other side of the manufactured polarizer and the λ / 2 liquid crystal retardation layer side of the λ / 2 liquid crystal retardation film were bonded to the manufactured first adhesive film, the base film was removed, and a laminate was manufactured in the following order: upper polarizer protective film - aqueous adhesive layer - polarizer - first adhesive film (thickness: 10 μm) - λ / 2 liquid crystal retardation layer.

[0131] A λ / 4 liquid crystal retardation film (FUJIFILM Corporation, hydrophobic, water contact angle 84° at 25°C, laminate of a λ / 4 liquid crystal retardation layer (thickness: 1 μm) and a substrate film) was prepared. The λ / 4 liquid crystal retardation layer side of the λ / 4 liquid crystal retardation film was not surface-treated with corona.

[0132] The λ / 2 liquid crystal retardation layer of the produced laminate and the λ / 4 liquid crystal retardation layer side of the λ / 4 liquid crystal retardation film were bonded to the produced first adhesive film, the base film was removed, and a polarizing plate was produced in the following order: upper polarizer protective film - aqueous adhesive layer - polarizer - first adhesive film (thickness: 10 μm) - λ / 2 liquid crystal retardation layer - second adhesive film (thickness: 10 μm) - λ / 4 liquid crystal retardation layer.

[0133] The prepared third adhesive film was attached to one side of the λ / 4 liquid crystal retardation layer of the manufactured polarizing plate, and a laminate for test specimens was manufactured by laminating the upper polarizer protective film-water-based adhesive layer-polarizer-first adhesive film (thickness: 10 μm)-λ / 2 liquid crystal retardation layer-second adhesive film (thickness: 10 μm)-λ / 4 liquid crystal retardation layer-third adhesive film (thickness: 25 μm). The physical properties shown in Table 1 below were evaluated.

[0134] <Examples 2 to 5 and Comparative Examples 1 to 4> A polarizing plate was manufactured in the same manner as in Example 1, except that the composition of the composition forming the first adhesive film in Example 1 was changed as shown in Table 1 below.

[0135] The physical properties of the first pressure-sensitive adhesive films, polarizing plates, and laminates for test pieces of the examples and comparative examples were evaluated in accordance with Table 1 below, and the results are shown in Table 1 below.

[0136] <Evaluation> (1) Adhesion to substrate (unit: kgf / 25 mm) The adhesion between the adhesive film and the adherend was measured according to the method specified in ASTM D3330. The upper polarizer protective film, aqueous adhesive layer, polarizer, first adhesive film (thickness: 10 μm), λ / 2 liquid crystal retardation layer, second adhesive film (thickness: 10 μm), λ / 4 liquid crystal retardation layer, and third adhesive film (thickness: 25 μm) prepared in the examples and comparative examples were laminated, and the laminate was cut into a polarizer TD × polarizer MD (25 mm × 200 mm) and attached to a glass surface. Using a texture analyzer with a 30 kgf load cell, the upper polarizer protective film, aqueous adhesive layer, polarizer, first adhesive film (thickness: 10 μm), and λ / 2 liquid crystal retardation layer laminate was peeled at 25°C and a pulling rate of 300 mm / min, and the peel load was measured.

[0137] (2) Reliability on a flat surface The upper polarizer protective film produced in the Examples and Comparative Examples - water-based adhesive layer - polarizer - first adhesive film (thickness: 10 μm) - λ / 2 liquid crystal retardation layer - second adhesive film (thickness: 10 μm) - λ / 4 liquid crystal retardation layer - third adhesive film (thickness: 25 μm) was laminated, and the laminate for test specimen was cut into polarizer MD × polarizer TD (120 mm × 80 mm), and then attached to a glass plate. A pressure of 4 kg / cm was applied. 2 ~5kg / cm 2 The test specimens were prepared while applying a pressure of 1000 kJ / cm.

[0138] The heat resistance of each manufactured test piece was evaluated by leaving it at a temperature of 85°C for 250 hours and then observing whether bubbles or peeling occurred. The humidity and heat resistance reliability was evaluated by leaving it at a relative humidity of 95% and a temperature of 60°C for 250 hours and then observing whether bubbles or peeling occurred. The evaluation criteria were as follows:

[0139] ○: No bubbles or peeling occurs. △: Some bubbles and peeling occurred. ×: A lot of bubbles and peeling occurs.

[0140] (3) Reliability on curved surfaces The upper polarizer protective film, water-based adhesive layer, polarizer, first adhesive film (thickness: 10 μm), λ / 2 liquid crystal retardation layer, second adhesive film (thickness: 10 μm), λ / 4 liquid crystal retardation layer, and third adhesive film (thickness: 25 μm) prepared in the examples and comparative examples were laminated. The laminates for test specimens were cut into polarizer MD × polarizer TD (120 mm × 80 mm) and fixed between two plates so that the curvature radius was 3 mm and 5 mm. The heat resistance properties of each test specimen in a bent state were evaluated by leaving it at a temperature of 85°C for 250 hours and observing for the occurrence of bubbles or peeling. The humidity and heat resistance reliability was evaluated by leaving it at a relative humidity of 95% and a temperature of 60°C for 250 hours and observing for the occurrence of bubbles or peeling. The evaluation criteria were as follows.

[0141] ○: No bubbles or peeling occurs. △: Some bubbles and peeling occurred. ×: A lot of bubbles and peeling occurs.

[0142] [Table 1]

[0143] The abbreviations in Table 1 are as follows: n-BA: n-butyl acrylate 4-HBA: 4-hydroxybutyl acrylate MPHA: N-(methacryloyloxy)propylheptadecanamide AM: acrylamide n-HDA: n-heptadecyl acrylate

[0144] As shown in Table 1, the polarizing plates of the examples have excellent adhesion to the substrate, preventing peeling from the substrate. Furthermore, the polarizing plates of the examples can adhere with high adhesion to a liquid crystal retardation layer with a high surface water contact angle without surface treatment, improving processability. Furthermore, the polarizing plates of the examples have excellent heat resistance reliability and humidity and heat resistance reliability on both flat and curved surfaces, making them applicable to both non-flexible and flexible display devices and providing excellent reliability.

[0145] On the other hand, the polarizing plate of the comparative example could not provide all of the effects of the polarizing plate of the example.

[0146] Simple variations and modifications of the present invention can be easily implemented by those skilled in the art, and all such variations and modifications can be considered to be included within the scope of the present invention. [Explanation of symbols]

[0147] 100: Polarizer 200: Protective layer 300: Adhesive film for first polarizing plate 400: 1st retardation layer

Claims

1. a copolymer of a monomer mixture containing an alkyl group-containing unsaturated monomer, a hydroxyl group-containing unsaturated monomer, and an unsaturated monomer having an amide group and a long-chain alkylene group or a long-chain alkyl group; An adhesive film for polarizing plates, comprising a cured product of a composition comprising a curing agent.

2. 2. The pressure-sensitive adhesive film for polarizing plates according to claim 1, wherein the pressure-sensitive adhesive film for polarizing plates has a substrate adhesion strength of 1.10 kgf / 25 mm or more to a substrate having a water contact angle of 70° or more.

3. The pressure-sensitive adhesive film for polarizing plates according to claim 2 , wherein the substrate is a liquid crystal layer.

4. the long-chain alkylene group is a linear or branched alkylene group having 8 to 20 carbon atoms, 2. The pressure-sensitive adhesive film for polarizing plates according to claim 1, wherein the long-chain alkyl group is a linear or branched alkyl group having 8 to 20 carbon atoms.

5. The pressure-sensitive adhesive film for polarizing plates according to claim 1 , wherein the unsaturated monomer having an amide group and a long-chain alkylene group or a long-chain alkyl group is represented by the following chemical formula 1: [Chemical formula 1] 【Chemistry 1】 (In the above Chemical Formula 1, R is hydrogen or an alkyl group having 1 to 5 carbon atoms; L １１ is a linear or branched alkylene group having 1 to 10 carbon atoms, L １２ is a linear or branched alkyl group having 8 to 20 carbon atoms.

6. The pressure-sensitive adhesive film for polarizing plates according to claim 1 , wherein the unsaturated monomer having an amide group and a long-chain alkylene group or a long-chain alkyl group is contained in the monomer mixture in an amount of 1 to 30% by weight.

7. 2. The adhesive film for polarizing plates according to claim 1, wherein the monomer mixture comprises 60% to 95% by weight of the alkyl group-containing unsaturated monomer, 0.1% to 10% by weight of the hydroxyl group-containing unsaturated monomer, and 1% to 30% by weight of the unsaturated monomer having an amide group and a long-chain alkylene group or a long-chain alkyl group.

8. 2. The adhesive film for polarizing plates according to claim 1, wherein the total amount of the alkyl group-containing unsaturated monomer, the hydroxyl group-containing unsaturated monomer, and the unsaturated monomer having an amide group and a long-chain alkylene group or a long-chain alkyl group is 95% by weight or more in the monomer mixture.

9. The pressure-sensitive adhesive film for polarizing plates according to claim 1 , wherein the curing agent includes an isocyanate-based curing agent.

10. A polarizer; A polarizing plate comprising: the adhesive film for a polarizing plate according to claim 1 laminated on a lower surface of the polarizer.

11. The polarizing plate according to claim 10 , wherein the polarizing plate is formed by sequentially stacking the polarizer, the adhesive film for a polarizing plate on one surface of the polarizer, and a liquid crystal retardation layer.

12. the polarizer is hydrophilic; The polarizer according to claim 11 , wherein the liquid crystal retardation layer is hydrophobic.

13. The polarizing plate according to claim 10, wherein the polarizing plate is formed by sequentially stacking the polarizer, the adhesive film for the polarizing plate on one surface of the polarizer, the first liquid crystal retardation layer, the adhesive film for the polarizing plate, and the second liquid crystal retardation layer.

14. the first liquid crystal retardation layer and the second liquid crystal retardation layer are each hydrophobic, The polarizing plate of claim 13 , wherein the polarizer is hydrophilic.

15. A display device comprising the polarizing plate of claim 10.

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