Polarizing plate and optical display device

Abstract

To provide a polarizing plate that sufficiently prevents permeation of iodine eluted from a polarizer into a retardation layer after the polarizing plate is left under high temperature and high humidity for a long time.SOLUTION: A polarizing plate includes a polarizer, and a first adhesive layer and a first retardation layer that are sequentially stacked on a lower surface of the polarizer. The first retardation layer has a light transmittance of 1.0% or less in a UVA wavelength region. The first adhesive layer includes a cured substance of a non(meth)acrylic composition including a curable compound and a photo-initiator. The curable compound includes (A) an epoxy compound. The epoxy compound includes a mixture of a bifunctional alicyclic epoxy compound, a bifunctional aromatic epoxy compound, and a bifunctional aliphatic epoxy compound. The photo-initiator includes a mixture of a iodonium photo-acid generator and an anthracene light increasing-decreasing agent. The anthracene light increasing-decreasing agent is contained by 0.5 parts by weight or more per 100 parts by weight of the curable compound.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Light-emitting element display devices such as OLEDs do not require a polarizing plate. However, light-emitting element display devices have a problem in that visibility and contrast are reduced due to reflection of external light caused by exposed electrodes. Therefore, it is preferable to provide an anti-reflection polarizing plate on the panel. A known example of an anti-reflection polarizing plate is a circular polarizing plate composed of a polarizer and a retardation layer. The retardation layer may be manufactured by stretching a resin, or a liquid crystal retardation layer may be used to thin the polarizing plate.

[0003] The liquid crystal retardation layer may be attached to the polarizer by an adhesive layer. It is preferable that the liquid crystal retardation layer is attached to the polarizer with a high peel strength. Furthermore, it is preferable that iodine eluted from the polarizer does not cause color change and corrosion of the liquid crystal retardation layer and / or the panel for optical display devices after the polarizing plate is left at high temperature and high humidity for a long period of time.

[0004] The background art of the present invention is described in Japanese Patent Application Laid-Open No. 2014-032270. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-032270 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a polarizing plate that can sufficiently prevent iodine eluted from a polarizer from penetrating into a retardation layer after being left at high temperature and high humidity for a long period of time.

[0007] Another object of the present invention is to provide a polarizing plate having a light transmittance of 1.0% or less in the UVA wavelength region and a high peel strength between a retardation layer and a polarizer or a protective layer. [Means for solving the problem]

[0008] One aspect of the present invention is a polarizing plate.

[0009] The polarizing plate includes a polarizer, and a first adhesive layer and a first retardation layer sequentially stacked on a lower surface of the polarizer. The first retardation layer has a light transmittance of 1.0% or less in the UVA wavelength region. The first adhesive layer includes a cured product of a non-(meth)acrylic composition including a curable compound and a photoinitiator. The curable compound includes an epoxy-based compound. The epoxy-based compound includes a mixture of a bifunctional alicyclic epoxy-based compound, a bifunctional aromatic epoxy-based compound, and a bifunctional aliphatic epoxy-based compound. The photoinitiator includes a mixture of an iodonium-based photoacid generator and an anthracene-based photoacid generator. The anthracene-based photoacid generator is included in an amount of 0.5 parts by weight or more based on 100 parts by weight of the curable compound.

[0010] Another aspect of the present invention is an optical display device.

[0011] An optical display device includes the polarizing plate of the present invention. [Effects of the Invention]

[0012] The present invention can provide a polarizing plate that can sufficiently prevent iodine eluted from a polarizer from penetrating into a retardation layer after being left at high temperature and high humidity for a long period of time.

[0013] The present invention can provide a polarizing plate having a light transmittance of 1.0% or less in the UVA wavelength region and a high peel strength between a retardation layer and a polarizer or a protective layer. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a cross-sectional view of a polarizing plate according to an 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. 1 is a schematic diagram showing a general explanation for evaluating iodine eluted from a polarizer (iodine discoloration phenomenon). DETAILED DESCRIPTION OF THE INVENTION

[0015] With reference to the accompanying drawings, the present invention will be described in detail with respect to the embodiments so that those skilled in the art can easily carry out the invention. The present invention may be realized 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.

[0016] In this specification, "upper" and "lower" are based on the drawings and are not necessarily fixed as upper and lower, and "upper" may be changed to "lower" and "lower" to "upper" depending on the viewpoint.

[0017] The terms used herein are merely used to describe exemplary embodiments and are not intended to limit the present invention. The singular expressions include the plural expressions unless the context clearly indicates otherwise.

[0018] In this specification, the "in-plane retardation (Re)" and the "thickness direction retardation" are represented by the following formula A and formula B, respectively:

[0019] [Formula A] Re=(nx-ny)×d

[0020] [Formula B] Rth=((nx+ny) / 2-nz)×d (In the mathematical formula A, nx, ny, and nz are the refractive indices in the slow axis direction of the optical element, the refractive index in the fast axis direction of the optical element, and the refractive index in the thickness direction at the measurement wavelength, respectively, and d is the thickness of the optical element (unit: nm).)

[0021] In this specification, "short wavelength dispersibility" is Re(450) / Re(550), "long wavelength dispersibility" is Re(650) / Re(550), and Re(450), Re(550), and Re(650) are the in-plane retardations of the optical element at wavelengths of 450 nm, 550 nm, and 650 nm, respectively.

[0022] In this specification, "reverse wavelength dispersibility" means that Re(450) < Re(550) < Re(650).

[0023] In this specification, the "UVA wavelength region" means the region with wavelengths from 320 nm to 390 nm.

[0024] In this specification, the "degree of polarization" means the value measured at wavelengths from 400 nm to 800 nm, specifically at a wavelength of 550 nm.

[0025] In this specification, "(meth)acrylic" means acrylic and / or methacrylic.

[0026] In this specification, when describing a numerical range, "X to Y" means "X or more and Y or less" (X ≤ and ≤ Y).

[0027] The polarizing plate of the present invention can sufficiently prevent the penetration of iodine decolorized or eluted from the polarizer into the retardation layer after being left for a long time at high temperature and high humidity. The present invention provides a polarizing plate having a high peeling force between the retardation layer with a light transmittance of 1.0% or less in the UVA wavelength region and the polarizer or the protective layer.

[0028] The polarizing plate according to one embodiment may be used as an anti-reflection polarizing plate in an organic light emitting device display device, etc. The polarizing plate according to one embodiment may be used in a flexible, foldable, or bendable optical display device that requires bending reliability.

[0029] In one embodiment, the polarizing plate includes a polarizer, and a first adhesive layer and a first retardation layer sequentially stacked on a lower surface of the polarizer. In one embodiment, the first adhesive layer and the first liquid crystal retardation layer may be located between the polarizer and a panel of an optical display device. In one embodiment, the first retardation layer may be adhered to the polarizer by the first adhesive layer.

[0030] 1st retardation layer The first retardation layer is located between the polarizer and the panel of the optical display device, and prevents reflection of external light by circularly polarizing the linearly polarized light emitted after external light passes through the polarizer, thereby achieving an anti-reflection function and improving the appearance and screen quality.

[0031] In one embodiment, the first retardation layer may have an in-plane retardation of 100 nm to 220 nm, specifically 100 nm to 180 nm, for example, λ / 4, at a wavelength of 550 nm. Within this range, the reflectance to external light can be reduced, and the effect of improving screen quality can be obtained.

[0032] In another specific example, the first retardation layer may have an in-plane retardation of 225 nm to 350 nm, specifically 225 nm to 300 nm, for example, λ / 2, at a wavelength of 550 nm. Within this range, the reflectance to external light can be reduced, and the effect of improving screen quality can be obtained.

[0033] In one embodiment, the first retardation layer can exhibit reverse wavelength dispersion, which enables the polarizer to provide improved anti-reflection function.

[0034] The first retardation layer has a light transmittance of 1.0% or less in the UVA wavelength range. For example, the first retardation layer may have a light transmittance of 0.0% to 0.8% in the UVA wavelength range. The light transmittance may be adjusted by the material forming the first retardation layer, the wavelength dispersion value of the first retardation layer, and the method of forming the first retardation layer with the material.

[0035] Although the present invention includes a first retardation layer having a light transmittance of 1.0% or less in the UVA wavelength region, the first adhesive layer is sufficiently cured to provide a high peel strength between the first retardation layer and the polarizer, and can sufficiently prevent iodine discolored or eluted from the polarizer from penetrating into the retardation layer after long-term storage at high temperature and humidity.

[0036] In one embodiment, the first retardation layer is a reverse wavelength dispersion liquid crystal retardation layer and may be formed from a composition for the first retardation layer containing a liquid crystal compound having at least one of an aromatic functional group and an alicyclic functional group. 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 to increase the strength of the liquid crystal retardation layer.

[0037] The composition for the first retardation layer 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 detailed types thereof may be referred to those known to those skilled in the art.

[0038] The first retardation layer may be transferred from the film for the first retardation layer to a polarizer or a protective layer. The film for the first retardation layer may include a first retardation layer and a substrate film located on one surface of the first retardation layer. The film for the first retardation layer may be formed by coating a composition for the first retardation layer to a predetermined thickness on one surface of the substrate film and then curing it. The substrate film may be a conventional film known to those skilled in the art, such as a polyethylene terephthalate or triacetyl cellulose film.

[0039] The first retardation layer may further include an alignment layer formed on a lower surface, i.e., a surface facing the first adhesive layer. When the first retardation layer is made of liquid crystal, the alignment layer controls the degree and / or direction of alignment of the liquid crystal, thereby enabling the first retardation layer to have desired wavelength dispersion and in-plane retardation.

[0040] The alignment film may be formed by coating and curing an alignment film-forming composition. According to one embodiment, the alignment film may be a rubbed film made of an organic compound such as a polymer, an obliquely evaporated film made of an inorganic compound, a film with microgrooves, or a film formed by stacking LB films made of organic compounds such as tricosanoic acid, dioctadecylmethylammonium chloride, or methyl stearate. Alternatively, the alignment film may be an alignment film that exhibits alignment function upon light irradiation. The alignment film-forming composition may include polyimide, polyvinyl alcohol, modified polyvinyl alcohol, or a polymer having a polymerizable group. The alignment treatment may be performed by rubbing the surface of a polymer layer, irradiating a photo-alignable material with polarized or unpolarized light, or heating a coating of the alignment film-forming composition.

[0041] In one embodiment, the first 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 in-plane retardation can be achieved.

[0042] 1st adhesive layer The first adhesive layer can bond the polarizer or the protective layer to the first retardation layer. The first adhesive layer can sufficiently prevent iodine bleached or eluted from the polarizer from penetrating into the retardation layer after the polarizing plate is left at high temperature and high humidity for a long period of time. The first adhesive layer can also increase the peel strength between the retardation layer having a light transmittance of 1.0% or less in the UVA wavelength range and the polarizer or the protective layer. The present invention is characterized in that the first adhesive layer includes, among the adhesive layers that suppress the penetration of bleached or eluted iodine into the retardation layer, an adhesive layer that increases the peel strength between the retardation layer having a light transmittance of 1.0% or less in the UVA wavelength range and the polarizer or the protective layer.

[0043] The first adhesive layer includes a cured product of a non-(meth)acrylic composition including a curable compound and a photoinitiator, the curable compound including an epoxy-based compound, the epoxy-based compound including a mixture of a bifunctional alicyclic epoxy-based compound, a bifunctional aromatic epoxy-based compound, and a bifunctional aliphatic epoxy-based compound, the photoinitiator including a mixture of an iodonium-based photoacid generator and an anthracene-based photoacid generator, and the anthracene-based photoacid generator is included in an amount of 0.5 parts by weight or more relative to 100 parts by weight of the curable compound.

[0044] The first adhesive layer includes a cured product of a non-(meth)acrylic composition including a curable compound and a photoinitiator, and the cured product may be a photocured product.

[0045] In one embodiment, the first adhesive layer can include a curable compound and a photoinitiator, wherein the curable compound and the photoinitiator are derived from the non-(meth)acrylic composition.

[0046] The composition is a non-(meth)acrylic composition. Here, "non-(meth)acrylic composition" means that the composition does not contain a (meth)acrylic component. It was confirmed that even when a mixture of an iodonium-based photoacid generator and an anthracene-based photosensitizer is used as a photoinitiator, a first adhesive layer formed from a composition using both an epoxy type and a (meth)acrylic type has a limit in increasing the peel strength between a retardation layer having a light transmittance of 1.0% or less in the UVA wavelength range and a polarizer or a protective layer.

[0047] The curable compound includes an epoxy compound (A), and the epoxy compound (A) includes a mixture of a difunctional alicyclic epoxy compound, a difunctional aromatic epoxy compound, and a difunctional aliphatic epoxy compound.

[0048] By satisfying the above-mentioned configuration, the curable compound in the first adhesive layer can easily increase the peel strength between the retardation layer having a light transmittance of 1.0% or less in the UVA wavelength region and the polarizer or protective layer.

[0049] The curable compound will be described in detail below.

[0050] In one embodiment, the curable compound may be a photocurable compound in an amount of 90 wt % or more, preferably 95 wt % to 100 wt %, based on the solid content of the composition, which may provide excellent effects in improving adhesive strength, reliability, and compatibility.

[0051] In one embodiment, the mixture may be included in an amount of 95 parts by weight or more, for example, 99 to 100 parts by weight, more preferably 100 parts by weight, based on 100 parts by weight of the curable compound. Within this range, excellent effects of improving adhesive strength, reliability, and compatibility may be achieved.

[0052] The epoxy-based compound includes a mixture of a difunctional alicyclic epoxy-based compound, a difunctional aromatic epoxy-based compound, and a difunctional aliphatic epoxy-based compound.

[0053] A polarizing plate including a first adhesive layer formed from a composition that does not contain the bifunctional alicyclic epoxy compound has a slow initial reaction rate, and therefore may have insufficient adhesive strength after UV curing, which may cause defects such as edge lifting during processing.

[0054] A polarizer including a first adhesive layer formed from a composition that does not contain the bifunctional aromatic epoxy compound may have reduced adhesion between the adhesive layer and the liquid crystal, and may easily peel off even with a small impact after curing, resulting in reduced processability and reliability issues.

[0055] A polarizing plate including a first adhesive layer formed from a composition that does not contain the bifunctional aliphatic epoxy compound has a high viscosity of 200 cps or more, which may cause coating problems and process defects of the adhesive.

[0056] In one embodiment, the total amount of the bifunctional alicyclic epoxy compound, the bifunctional aromatic epoxy compound, and the bifunctional aliphatic epoxy compound may be 95 parts by weight or more, preferably 99 to 100 parts by weight, and more preferably 100 parts by weight, per 100 parts by weight of the epoxy compound (A). Within this range, the effects of the present invention may be easily achieved.

[0057] The bifunctional alicyclic epoxy compound may include a compound having a carbon chain between two alicyclic epoxy groups. For example, the bifunctional alicyclic epoxy compound may include one or more of 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, 1,2-epoxy-4-vinylcyclohexane, 1,2-epoxy-1-methyl-4-(1-methylepoxyethyl)cyclohexane, 4-(1,2-epoxyethyl)-1,2-epoxycyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol, ethylene bis(3,4-epoxycyclohexanecarboxylate), oxydiethylene bis(3,4-epoxycyclohexanecarboxylate), 1,4-cyclohexanedimethyl bis(3,4-epoxycyclohexanecarboxylate), and 3-(3,4-epoxycyclohexylmethoxycarbonyl)propyl 3,4-epoxycyclohexanecarboxylate. One or more of the compounds may be included, or two or more of the compounds may be included. Among the difunctional alicyclic epoxy compounds, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate may be used.

[0058] The bifunctional alicyclic epoxy compound may be included in an amount of 5 to 30 parts by weight, for example, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, 20 parts by weight, 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight, or 30 parts by weight, 5 parts by weight to 25 parts by weight, or 10 parts by weight to 20 parts by weight, based on 100 parts by weight of the curable compound. Within this range, initial adhesion is achieved through a fast initial curing reaction, and defects are not caused even during high-speed processing. Furthermore, the reaction heat generated by the curing can also promote the reaction of the difunctional aromatic epoxy compound and the difunctional aliphatic epoxy compound, which can make it easier to achieve the above-mentioned effects of the present invention.

[0059] The difunctional aromatic epoxy compound may be more effective in increasing the peel strength between a retardation layer having a light transmittance of 1.0% or less in the UVA wavelength region and a polarizer or protective layer than a monofunctional aromatic epoxy compound.

[0060] In one embodiment, the difunctional aromatic epoxy compound may be a diglycidyl ether compound, which may facilitate the adhesive composition of the present invention to provide the effects of the present invention.

[0061] For example, the difunctional aromatic epoxy compound may include one or more of diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and propylene oxide of bisphenol A.

[0062] For example, the bifunctional aromatic epoxy compound is used in an amount of 5 to 60 parts by weight, preferably 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, 20 parts by weight, 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight, 30 parts by weight, 31 parts by weight, 32 parts by weight, 33 parts by weight, 34 parts by weight, 35 parts by weight, 36 parts by weight, 37 parts by weight, 38 parts by weight, 39 parts by weight, 40 parts by weight, 41 parts by weight, 42 parts by weight, 43 parts by weight, 44 parts by weight, 45 parts by weight, 46 parts by weight, 47 parts by weight, 48 parts by weight, 49 parts by weight, 50 parts by weight, 51 parts by weight, 52 parts by weight, 53 parts by weight, 54 parts by weight, 55 parts by weight, 56 parts by weight, 57 parts by weight, 58 parts by weight, 59 parts by weight, 60 parts by weight, 61 parts by weight, 62 parts by weight, 63 parts by weight, 64 parts by weight, 65 parts by weight, 66 parts by weight, 67 parts by weight, 68 parts by weight, 69 parts by weight, 70 parts by weight, 71 parts by weight, 72 parts by weight, 73 parts by weight, 74 parts by weight, 75 parts by weight It may be included in an amount of 1 part by weight, 32 parts by weight, 33 parts by weight, 34 parts by weight, 35 parts by weight, 36 parts by weight, 37 parts by weight, 38 parts by weight, 39 parts by weight, 40 parts by weight, 41 parts by weight, 42 parts by weight, 43 parts by weight, 44 parts by weight, 45 parts by weight, 46 parts by weight, 47 parts by weight, 48 parts by weight, 49 parts by weight, 50 parts by weight, 51 parts by weight, 52 parts by weight, 53 parts by weight, 54 parts by weight, 55 parts by weight, 56 parts by weight, 57 parts by weight, 58 parts by weight, 59 parts by weight, or 60 parts by weight, 10 parts by weight to 60 parts by weight, more preferably 15 parts by weight to 50 parts by weight. In this range, it may be easy to increase the peel strength between the retardation layer having a light transmittance of 1.0% or less in the UVA wavelength region and the polarizer or protective layer.

[0063] The bifunctional aliphatic epoxy compound has the characteristic of having a long induction period due to stabilization caused by hydrogen bonding with adjacent oxygen atoms after the epoxy ring is protonated by a cation. The bifunctional aliphatic epoxy compound undergoes post-reaction after the long induction period. This can provide benefits such as increased peel strength and improved reliability at high temperatures and humidity.

[0064] The difunctional aliphatic epoxy compound may be more effective in increasing the peel strength between a retardation layer having a light transmittance of 1.0% or less in the UVA wavelength region and a polarizer or protective layer than a monofunctional aliphatic epoxy compound.

[0065] In one embodiment, the bifunctional aliphatic epoxy compound may be a diglycidyl ether compound, which makes it easier for the adhesive composition to exhibit the effects of the present invention.

[0066] For example, the bifunctional aliphatic epoxy compound may include one or more of a substituted or unsubstituted, linear or branched diglycidyl ether compound having a main chain of an alkylene group having 3 or more carbon atoms, and a substituted or unsubstituted diglycidyl ether compound having ethylene oxide or propylene oxide in the molecule. Here, "substituted" means that one or more hydrogen atoms of the functional group are substituted with an alkyl group having 1 to 5 carbon atoms. Here, "number of carbon atoms" refers only to the number of carbon atoms contained in the main chain of the linear or branched alkylene group.

[0067] Preferably, a diglycidyl ether compound having a main chain of an alkylene group of 3 or more carbon atoms, which is substituted or unsubstituted, linear or branched, may be used as the bifunctional aliphatic epoxy compound, and this compound is more likely to exhibit the effects of the present invention than a diglycidyl ether compound having ethylene oxide or propylene oxide in the molecule.

[0068] The diglycidyl ether compound having a substituted or unsubstituted, linear or branched alkylene group main chain having 3 or more carbon atoms may have a linear or branched alkylene group main chain having 3 or more carbon atoms, preferably 3 to 10 carbon atoms, and more preferably 3 to 6 carbon atoms.

[0069] For example, the diglycidyl ether compound may be one or more of 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, and neopentyl glycol diglycidyl ether. Preferably, the diglycidyl ether compound may be neopentyl glycol diglycidyl ether.

[0070] Diglycidyl ether compounds having ethylene oxide or propylene oxide in the molecule are more likely to exhibit the effects of the present invention because 2 or more moles of ethylene oxide or propylene oxide in the molecule provide a reaction retarding effect.

[0071] The diglycidyl ether compound having 2 or more moles of ethylene oxide or propylene oxide in the molecule may be a diglycidyl ether compound having 2 to 10 moles of ethylene oxide or propylene oxide in the molecule, for example, one or more of polyethylene glycol diglycidyl ether and polypropylene glycol diglycidyl ether.

[0072] The bifunctional aliphatic epoxy compound may be contained in the curable compound in an excess amount relative to each of the bifunctional alicyclic epoxy compound and the bifunctional aromatic epoxy compound, which may facilitate the realization of the above-described effects of the present invention.

[0073] For example, the bifunctional aliphatic epoxy compound is used in an amount of 25 to 70 parts by weight, preferably 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight, 30 parts by weight, 31 parts by weight, 32 parts by weight, 33 parts by weight, 34 parts by weight, 35 parts by weight, 36 parts by weight, 37 parts by weight, 38 parts by weight, 39 parts by weight, 40 parts by weight, 41 parts by weight, 42 parts by weight, 43 parts by weight, 44 parts by weight, 45 parts by weight, 46 parts by weight, 47 parts by weight, 48 parts by weight, 49 parts by weight, 50 parts by weight, 51 parts by weight, 52 parts by weight, 53 parts by weight, 54 parts by weight, 55 parts by weight, 56 parts by weight, 57 parts by weight, 58 parts by weight, 59 parts by weight, 60 parts by weight, 61 parts by weight, 62 parts by weight, 63 parts by weight, 64 parts by weight, 65 parts by weight, 66 parts by weight, 67 parts by weight, 68 parts by weight, 69 parts by weight, 70 parts by weight, 71 parts by weight, 72 parts by weight, 73 parts by weight, 74 parts by weight, 75 parts by weight, 76 parts by weight, 77 parts by weight, 78 parts by weight, 79 parts by weight, 80 parts by weight, 81 parts by weight, 82 parts by weight, 83 parts by weight, 84 parts by weight, 85 parts by weight, 86 parts by weight, 87 parts by weight, 88 parts by weight, 89 parts by weight, 90 parts by weight, 91 parts by weight, 92 parts by weight, 93 parts by Parts by weight, 46 parts by weight, 47 parts by weight, 48 parts by weight, 49 parts by weight, 50 parts by weight, 51 parts by weight, 52 parts by weight, 53 parts by weight, 54 parts by weight, 55 parts by weight, 56 parts by weight, 57 parts by weight, 58 parts by weight, 59 parts by weight, 60 parts by weight, 61 parts by weight, 62 parts by weight, 63 parts by weight, 64 parts by weight, 65 parts by weight, 66 parts by weight, 67 parts by weight, 68 parts by weight, 69 parts by weight, or 70 parts by weight, 30 to 65 parts by weight, more preferably 35 to 60 parts by weight. Within this range, it may be easy to increase the peel strength between the retardation layer having a light transmittance of 1.0% or less in the UVA wavelength region and the polarizer or protective layer.

[0074] Photoinitiator The photoinitiator includes a mixture of an iodonium-based photoacid generator and an anthracene-based photosensitizer, and the anthracene-based photosensitizer is included in an amount of 0.5 parts by weight or more based on 100 parts by weight of the curable compound.

[0075] In the present invention, in order to provide a first retardation layer having a light transmittance of 1.0% or less in the UVA wavelength region, preferably a high peel strength between the liquid crystal retardation layer and the polarizer or protective layer, the curable compound contains the photoinitiator in an epoxy compound.

[0076] The combination of an iodonium-based photoacid generator with a thioxanthone-based photoacid generator, and the combination of a sulfonium-based photoacid generator with an anthracene-based photoacid generator, are each capable of ensuring peel strength and reliability at high temperatures and humidity under typical UV irradiation conditions. However, in environments where energy in the UVA region is blocked, such as with liquid crystal layers with reverse wavelength dispersion, performance declines, resulting in peeling after high temperatures and humidity, or the polarizer being severely decolorized by iodine.

[0077] It was confirmed that the combination of an iodonium-based photoacid generator and an anthracene-based photoacid generator exacerbates the problems of peeling and iodine discoloration at high temperatures and humidity. Analysis of the reaction rate revealed that an anthracene-based photoacid generator is unable to significantly increase the reaction conversion rate of (meth)acrylic compounds compared to a thioxanthone-based photoacid generator, and therefore does not undergo sufficient reaction in the final curing reaction.

[0078] However, in the case of the composition of the present invention containing only an epoxy compound without containing a (meth)acrylic compound as a curable compound, the anthracene-based photosensitizer, unlike the thioxanthone-based photosensitizer, minimizes the curing degradation caused by the reverse wavelength dispersion liquid crystal retardation layer, and as a result, it is thought that good results were achieved in the adhesion of the reverse wavelength dispersion liquid crystal retardation layer.

[0079] In one embodiment, the weight ratio of the iodonium-based photoacid generator to the anthracene-based photoacid generator may be 3:1 to 10:1, for example, 4:1 to 8:1. In this range, the peel strength between the first retardation layer and the polarizer may be increased.

[0080] Separately, it was confirmed that in the combination of a sulfonium-based photoacid generator having a relatively long wavelength absorption region and an anthracene-based photosensitizer, the curing level was rapidly reduced by the reverse wavelength liquid crystal retardation layer.

[0081] In one embodiment, the iodonium-based photoacid generator may be a diaryliodonium-based photoacid generator.

[0082] Meanwhile, the anthracene-based photosensitizer is included in an amount of 0.5 parts by weight or more relative to 100 parts by weight of the curable compound. When the anthracene-based photosensitizer is included in an amount of 0.5 parts by weight or more, it is believed that the epoxy compound is cured at a high cure rate and is more likely to exhibit high peel strength. For example, the anthracene-based photosensitizer may be included in an amount of 0.5 to 6 parts by weight, 0.5 parts by weight, 1 part by weight, 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 3.5 parts by weight, 4 parts by weight, 4.5 parts by weight, 5 parts by weight, 5.5 parts by weight, or 6 parts by weight, or 0.5 to 3 parts by weight, relative to 100 parts by weight of the curable compound.

[0083] The anthracene-based photosensitizer may include an alkoxy-containing anthracene-based photosensitizer, for example, the anthracene-based photosensitizer may be an anthracene-based compound represented by the following formula 1:

[0084] [ka] (In the above Chemical Formula 1, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 are each independently hydrogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted mono- or polyalkyleneoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, a substituted or unsubstituted arylalkyl group having 7 to 20 carbon atoms, a halogen atom, a hydroxyl group, an amino group (-NH2), or a thiol group (-SH); and R1, R2, R3, R4, R5, R6, R7, R8, R9, and R 10 wherein one or more of the groups is a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms.

[0085] Preferably, R1, R2, R3, R4, R5, R6, R7, R8, R9, and R 10At least two of the groups may be substituted or unsubstituted alkoxy groups having 1 to 5 carbon atoms, and the anthracene-based photosensitizer may be a dialkoxyanthracene-based photosensitizer. Here, in "substituted or unsubstituted," "substituted" means that a hydrogen atom in one or more functional groups is substituted with an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an aryl group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen, a hydroxyl group, an amino group, or the like.

[0086] For example, the anthracene-based photosensitizer may be 9,10-dimethoxyanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, 9,10-diisopropoxyanthracene, 9,10-dibutoxyanthracene, 9,10-dipentyloxyanthracene, 9,10-dihexyloxyanthracene, 9,10-bis(2-methoxyethoxy)anthracene, 9,10-bis(2-ethoxyethoxy)anthracene, 9,10-bis(2-butoxyethoxy)anthracene, 9,10-bis(3-butoxypropyl ... 2-methyl- or 2-ethyl-9,10-dipropoxyanthracene, 2-methyl- or 2-ethyl-9,10-dimethoxyanthracene, 2-methyl- or 2-ethyl-9,10-diethoxyanthracene, 2-methyl- or 2-ethyl-9,10-dipropoxyanthracene, 2-methyl- or 2-ethyl-9,10-diisopropoxyanthracene, 2-methyl- or 2-ethyl-9,10-dibutoxyanthracene, 2-methyl- or 2-ethyl-9,10-dipentyloxyanthracene, 2-methyl- or 2-ethyl-9,10-dihexyloxyanthracene, and the like.

[0087] Preferably, the anthracene-based photosensitizer may be 9,10-dimethoxyanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, 9,10-diisopropoxyanthracene, 9,10-dibutoxyanthracene, 9,10-dipentyloxyanthracene, 9,10-dihexyloxyanthracene, and more preferably 9,10-dibutoxyanthracene.

[0088] The iodonium-based photoacid generator may contain an onium salt of an iodonium cation and an anion. Specific examples of the iodonium cation include diaryliodonium salts such as diphenyliodonium, 4-methoxydiphenyliodonium, bis(4-methylphenyl)iodonium, bis(4-tert-butylphenyl)iodonium, bis(dodecylphenyl)iodonium, and (4-methylphenyl)[(4-(2-methylpropyl)phenyl)iodonium]. Specific examples of the anion include tetrafluoroborate (BF4 - ), hexafluorophosphate (PF6 - ), hexafluoroantimonate (SbF6 - ), hexafluoroarsenate (AsF6 - ), hexachloroantimonate (SbCl6 - Preferably, the iodonium-based photoacid generator may be (4-methylphenyl)[(4-(2-methylpropyl)phenyl)iodonium hexafluorophosphate.

[0089] The photoacid generator may be included in an amount of 0.5 to 10 parts by weight, for example, 1 to 6 parts by weight, based on 100 parts by weight of the curable compound. Within this range, the adhesive composition can be sufficiently cured, and problems such as a decrease in adhesive strength and bleeding out of the photocationic initiator can be avoided.

[0090] In one embodiment, the mixture of the iodonium-based photoacid generator and the anthracene-based photosensitizer may be included in the photoinitiator in an amount of 80 wt % or more, for example, 80 wt % to 100 wt %, or 100 wt %. This range may facilitate increasing the peel strength between the first retardation layer and the polarizer.

[0091] The composition may further comprise a naphthalene-based photosensitizer as a photosensitizer.

[0092] The naphthalene-based photosensitizer can compensate for the insufficient photoinitiation reaction caused by the anthracene-based photosensitizer. The naphthalene-based photosensitizer may be a conventional type known to those skilled in the art. The naphthalene-based photosensitizer may be included in an amount of 0.5 parts by weight or more, for example, 0.5 to 6 parts by weight, or 1 to 6 parts by weight, based on 100 parts by weight of the curable compound. This range may facilitate the compensation of the insufficient photoinitiation reaction.

[0093] In the composition, the total amount of the photoacid generator and the photosensitizer, i.e., the photoinitiator, may be 2 parts by weight or more, for example, 3 to 10 parts by weight, based on 100 parts by weight of the curable compound.

[0094] The composition may be prepared by mixing the curable compound and the photoinitiator, and may be a solvent-free composition or may further contain a solvent to improve coating properties.

[0095] The composition may further contain an antioxidant, an ultraviolet absorber, an ionic conductive agent, a conductivity-imparting additive such as conductive metal oxide fine particles, a light-diffusing additive, a viscosity adjuster, etc., within a range that does not impair the effects of the present invention.

[0096] The cured product of the composition, i.e., the first adhesive layer, may have a glass transition temperature of 30° C. to 150° C., preferably 50° C. to 120° C. This range may be effective in preventing layer separation during cutting and cracking under thermal shock conditions.

[0097] The first adhesive layer may be formed by photocuring the composition, which may be carried out by a conventional method known to those skilled in the art.

[0098] The first adhesive layer may have a thickness of 1.0 μm to 6.0 μm, for example, 2.0 μm to 5.0 μm. The first adhesive layer in this range can be used in a polarizing plate.

[0099] Polarizer A polarizer can polarize external or internal light.

[0100] 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.

[0101] The polarizer may have a thickness of 1 μm to 50 μm, which allows the polarizer to be used in optical display devices.

[0102] The polarizing plate may further include a protective layer on at least one surface of the polarizer, and the polarizing plate may include one or more protective layers.

[0103] protective layer The protective layer may be formed on at least one surface of the polarizer to protect the polarizer or to provide an additional function to the polarizer.

[0104] The protective layer may include one or more of an optically transparent protective film and a protective coating layer.

[0105] 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, poly(meth)acrylate-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.

[0106] When the protective layer is a protective coating layer type, it can have good adhesion to the polarizer, transparency, mechanical strength, thermal stability, moisture blocking properties, 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.

[0107] 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.

[0108] In addition to the optically transparent resin or the active energy ray-curable compound, the protective layer may further contain additives known to those skilled in the art, such as antioxidants, UV absorbers, ionic conductive agents, conductivity-imparting additives such as conductive metal oxide particles, light-diffusing additives, and viscosity modifiers.

[0109] 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. The protective layer in this range can be used in an optical display device.

[0110] 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.

[0111] 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 photo-curable adhesive. The water-based adhesive and the photo-curable adhesive may be appropriately used in accordance with the contents known to those skilled in the art.

[0112] When the protective layer is laminated on the polarizer opposite the first adhesive layer, the protective layer may be called an upper protective layer. In this case, the upper protective layer may include a UV absorber. The UV absorber can prevent damage to optical elements, such as light-emitting elements, in an optical display panel due to external light.

[0113] In one embodiment, the upper protective layer may have a light transmittance of 50% or less, for example, 30% or less, in the 380 nm wavelength region, which may be sufficient to prevent damage to the light emitting device due to external light.

[0114] The polarizing plate may further include a second retardation layer, and the polarizing plate may include one or more second retardation layers.

[0115] Second retardation layer The second retardation layer circularly polarizes the linearly polarized light emitted from the external light after the external light passes through the polarizer, thereby preventing reflection of the external light and realizing an anti-reflection function, thereby improving the appearance and screen quality.

[0116] In one embodiment, the second retardation layer may have an in-plane retardation of 100 nm to 220 nm, specifically 100 nm to 180 nm, for example, λ / 4, at a wavelength of 550 nm. Within this range, the reflectance of external light can be reduced, thereby improving the image quality.

[0117] The second retardation layer may have a different in-plane retardation at a wavelength of 550 nm than the first retardation layer. A polarizing plate including two retardation layers having different in-plane retardations can have a more improved anti-reflection effect than a polarizing plate including a single retardation layer.

[0118] In another example, the second retardation layer may have an in-plane retardation of 225 nm to 350 nm, specifically 225 nm to 300 nm, for example, λ / 2, at a wavelength of 550 nm. Within this range, the reflectance to external light can be reduced, thereby improving the image quality.

[0119] In one embodiment, the second retardation layer may be a positive C retardation layer (nz>nx=ny). For example, the second retardation layer may have a negative thickness retardation at a wavelength of 550 nm, for example, −200 nm to −10 nm.

[0120] The second retardation layer may be a liquid crystal retardation layer or a non-liquid crystal retardation layer.

[0121] When the second retardation layer is a liquid crystal retardation layer, the second retardation layer may be formed of a composition substantially the same as or similar to the composition for the first liquid crystal retardation layer. When the second retardation layer is a non-liquid crystal retardation layer, the second retardation layer may be a coating layer or a film formed of an optically transparent non-liquid crystal material.

[0122] The second retardation layer may have a thickness of 0.1 μm to 40 μm, for example, 1 μm to 5 μm, or 10 μm to 30 μm. Within this range, the polarizing plate can be made thinner and a target retardation can be achieved.

[0123] The polarizing plate may further include a second adhesive layer.

[0124] 2nd adhesive layer The second adhesive layer may be located on the lower surface of the polarizer and may bond the first retardation layer and the second retardation layer to each other.

[0125] In one embodiment, the second adhesive layer may include a cured product of a water-based adhesive or a photo-curable adhesive known to those skilled in the art. The water-based adhesive may include an aqueous solvent, a polyvinyl alcohol-based resin, and a crosslinking agent. The photo-curable adhesive may include an epoxy-based compound, a (meth)acrylic compound, and a photoinitiator. The polyvinyl alcohol-based resin, the crosslinking agent, the epoxy-based compound, the (meth)acrylic compound, and the photoinitiator may be of the usual types known to those skilled in the art.

[0126] For example, the second adhesive layer may be formed of a composition including the curable compound and photoinitiator described for the first adhesive layer, in which case the polarizing plate according to the present invention may exhibit a low change in light transmittance after high temperature and humidity, excellent bending reliability after high temperature and humidity, no cracking of the polarizer after thermal shock, and minimized discoloration of iodine after high temperature and humidity may be even more excellent.

[0127] The description of the curable compound and the photoinitiator is substantially the same as that described above, and therefore, the description thereof will be omitted.

[0128] FIG. 1 is a cross-sectional view of a polarizing plate according to an embodiment of the present invention.

[0129] Referring to FIG. 1, the polarizing plate includes a polarizer 10, an upper protective layer 20 laminated on the upper surface of the polarizer 10, a first adhesive layer 30 and a first retardation layer 40 laminated in sequence on the lower surface of the polarizer 10, and the polarizer 10 and the first retardation layer 40 may be bonded to each other by the first adhesive layer 30.

[0130] FIG. 2 is a cross-sectional view of a polarizing plate according to another embodiment of the present invention.

[0131] 2, the polarizing plate may include a polarizer 10, an upper protective layer 20 laminated on an upper surface of the polarizer 10, a first adhesive layer 30, a first retardation layer 40, a second adhesive layer 50, and a second retardation layer 60 laminated in this order on a lower surface of the polarizer 10. The polarizer 10 and the first retardation layer 40 may be bonded together by the first adhesive layer 30, and the first retardation layer 40 and the second retardation layer 60 may be bonded together by the second adhesive layer 50.

[0132] Although not shown in FIGS. 1 and 2, a functional coating layer, such as a hard coating layer, an anti-fingerprint layer, or an anti-reflection layer, may be further formed on the upper surface of the upper protective layer 20.

[0133] Although not shown in FIGS. 1 and 2, when the upper protective layer 20 is a protective film type, an adhesive layer can be further formed between the protective layer and the polarizer.

[0134] Although not shown in Figures 1 and 2, 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.

[0135] A method for manufacturing a polarizing plate according to one embodiment will be described below.

[0136] The manufacturing method may include the steps of: preparing a laminate of an upper protective layer and a polarizer; preparing a coating for a first adhesive layer by applying the composition for a first adhesive layer to one surface of a film for a liquid crystal retardation layer; bonding the coating for the first adhesive layer to one surface of the laminate, preferably one surface of a polarizer; irradiating UV light from the film for a liquid crystal retardation layer side toward the laminate; and transferring the liquid crystal retardation layer by peeling off a substrate film of the film for a liquid crystal retardation layer.

[0137] The UV irradiation for forming the first adhesive layer was performed by irradiating light in the UVA wavelength range at 500 mJ / cm 2 ~1000mJ / cm 2 The process may include irradiating the area with a light intensity of 10 to 60 seconds.

[0138] An optical display device according to an embodiment of the present invention includes the polarizer of the present invention. For example, the optical display device may be a light emitting device display device having a light emitting element, a liquid crystal display device, or the like.

[0139] The structure and operation of the present invention will be described in more detail below through preferred examples of the present invention, which are presented as preferred examples of the present invention and should not be construed as limiting the present invention in any way. [Example]

[0140] Example 1 (1) Preparation of adhesive composition for first adhesive layer The epoxy compounds were a mixture of 12.5 parts by weight of a difunctional alicyclic epoxy compound (A), 37.5 parts by weight of a difunctional aromatic epoxy compound (B1), and 50 parts by weight of a difunctional aliphatic epoxy compound (D), for a total of 100 parts by weight. The epoxy compounds were mixed with 4 parts by weight of an iodonium-based photoacid generator (G) and 1 part by weight of an anthracene-based photoacid generator (I) to prepare a solventless composition. The composition did not contain a (meth)acrylate compound.

[0141] (2) Polarizing plate manufacturing A polyvinyl alcohol film (PE30, degree of polymerization: 2800, Mitsubishi Chemical Corporation, thickness before stretching: 30 μm) was dyed by immersion in a 0.3% iodine aqueous solution, and then stretched in the machine direction (MD) at a uniaxial stretching ratio of 5.0. The stretched polyvinyl alcohol film was immersed in an aqueous solution containing 3% boric acid and 2% potassium iodide to correct the hue, and then dried at 50°C for 4 minutes to produce a polarizer (light transmittance: 45%, thickness: 7 μm).

[0142] As the upper protective layer for the polarizer, a cyclic olefin polymer (COP) film (thickness: 25 μm, Zeon, containing a UV absorber) with a hard coating layer formed on one side was prepared, and the other side was subjected to surface treatment using a corona treatment machine (AFS) at a speed of 10 mpm and an output of 1000 W.

[0143] As a lower polarizer protective film, a triacetyl cellulose film (Normal TAC, thickness: 40 μm) was prepared without saponification treatment.

[0144] Mitsubishi Chemical's acetoacetyl-containing polyvinyl alcohol resin Z200 (average polymerization degree: 1200, saponification degree: 98.5 mol%, acetoacetylation degree: 5 mol%) was dissolved in 95°C water for 60 minutes and then allowed to cool completely to room temperature before use. Daiichi Kigenso Chemical Industry's Zircosol-ZN, a crosslinking agent, was added to the polyvinyl alcohol aqueous solution at 0.1 wt% and mixed to create a water-based adhesive.

[0145] The aqueous adhesive prepared above was applied to one surface and the other surface of the prepared polarizer to a predetermined thickness, and then the upper polarizer protective film was attached to one surface of the polarizer, and the lower polarizer protective film was attached to the other surface of the polarizer. The resulting mixture was dried at 80°C for 3 minutes, and then the lower polarizer protective film was removed to prepare a polarizing plate laminate.

[0146] As the first liquid crystal retardation layer film, a film was prepared in which an alignment film and a liquid crystal retardation layer (expressing 1 / 4 in-plane retardation at a wavelength of 550 nm, reverse wavelength dispersion, light transmittance in the UVA region: 0.5%, containing aromatic groups, thickness: 2 μm, DNP) were sequentially formed on the upper surface of a polyethylene terephthalate (PET) film (thickness: 80 μm, light transmittance in the UVA region: 80%). The surface of the liquid crystal retardation layer was subjected to surface treatment using a corona treatment machine (AFS) at a speed of 10 mpm and an output of 1000 W.

[0147] The adhesive composition for the first adhesive layer was applied to the corona-treated surface of the liquid crystal retardation layer to a thickness of about 3 μm, and the surface of the polarizing plate laminate from which the lower polarizer protective film had been removed was then bonded to the liquid crystal retardation layer. Then, a metal halide lamp was used to irradiate the liquid crystal retardation layer with about 1000 mJ / cm2 of UVA standard from the PET film side. 2 After photo-curing by irradiating with a light amount of 1000 W, the PET film was removed, and a polarizing plate having the upper polarizer protective film-adhesive layer-polarizer-first adhesive layer-first liquid crystal retardation layer-alignment film laminated in this order was manufactured.

[0148] Examples 2 to 4 In Example 1, when preparing a total of 100 parts by weight of the epoxy-based compounds in the adhesive composition for the first adhesive layer, the adhesive composition and polarizing plate were prepared in the same manner, except that the type and / or content of each component was changed as shown in Table 1 below, and the type and / or content of each component of the photoacid generator and photosensitizer was changed as shown in Table 1 below. In Table 1 below, "-" means that the corresponding component was not included.

[0149] Comparative Examples 1 to 9 In Example 1, when preparing a total of 100 parts by weight of the epoxy-based compounds in the adhesive composition for the first adhesive layer, the adhesive composition and polarizing plate were prepared in the same manner, except that the type and / or content of each component was changed as shown in Table 1 below, and the type and / or content of each component of the photoacid generator and photosensitizer was changed as shown in Table 1 below. In Table 1 below, "-" means that the corresponding component was not included.

[0150] The polarizing plates manufactured in the examples and comparative examples were evaluated for physical properties as shown in Table 2 below, and the results are shown in Table 2 below.

[0151] (1) Bleaching after high temperature and humidity The polarizing plates prepared in the Examples and Comparative Examples were cut into squares measuring 50mm x 50mm with the polarizer's light absorption axis angled at 45°, and attached to glass plates using an adhesive layer to prepare test specimens. The test specimens were placed in a chamber at 60°C and 95% relative humidity for 500 hours and then removed. As shown in Figure 3, the length 2 at which iodine discoloration occurred on test specimen 1 was measured diagonally from each of the four corners of the specimen, and the level was classified as follows:

[0152] ◎: Less than 0.5 mm ○: 0.5mm or more and less than 1mm △: 1mm or more and less than 3mm ×: 3mm or more

[0153] (2) Transfer rate of reverse wavelength dispersion liquid crystal retardation layer The adhesive composition for the first adhesive layer was applied to a thickness of approximately 3 μm on the surface of the liquid crystal retardation layer that had been corona-treated using the methods described in the Examples and Comparative Examples. The adhesive composition for the first adhesive layer was then attached to the surface of the polarizing plate laminate from which the lower polarizer protective film had been removed, to prepare a test specimen. The test specimen was placed in a curing machine and irradiated with UV light from the liquid crystal retardation layer side to cure the first adhesive layer. UV irradiation was performed using a metal halide lamp with UVA at the light intensity shown in Table 2 below. The time when the test specimen left the curing machine was set to 0 seconds. After the scheduled time had elapsed, the test specimen was removed, and the substrate film of the film for the liquid crystal retardation layer was manually removed in one go. The degree of transfer of the liquid crystal retardation layer was evaluated by evaluating whether the liquid crystal retardation layer was completely peeled off without remaining on the substrate film when the substrate film was removed.

[0154] The degree of transfer of the liquid crystal retardation layer can be confirmed through reflective visual perception when the polarizer is applied to an optical display device. The polarizer was placed on a light-emitting device display device, and an upper protective layer was placed on top. The ratio of the area that appeared black due to the anti-reflection function when external light was irradiated to the entire area of ​​the polarizer was calculated. A higher ratio of the area indicates a higher degree of transfer of the liquid crystal retardation layer and a higher peel strength between the polarizer and the liquid crystal retardation layer.

[0155] (3) Reaction conversion rate The compositions for the first adhesive layer prepared in the examples and comparative examples were applied to a thickness of 3 μm between the polarizer and one side of the COP film. The other side of the COP film was partially covered with the film for the first liquid crystal retardation layer prepared in the examples and comparative examples. Then, UV was irradiated from the entire surface of the COP film under predetermined conditions (UVA standard light intensity 1000 mJ / cm2). 2 After the COP film was removed, the reaction conversion rate was measured using FT-IR.

[0156] [Table 1]

[0157] In Table 1, A) Multi-functional cycloaliphatic epoxy resin (Celloxide 2021P, Daicel) B1) Diglycidyl ether of bisphenol A (YD128, Kokuto Kagaku) B2) BPA-PO epoxy resin (EP-4000S, Adeka) B3) Diglycidyl ether of bisphenol F (YDF170, Kokuto Chemical) C) Dicyclopentadienyl dimethanol epoxy resin (EP-4088S, Adeka) D) Neopentyl glycol diglycidyl ether (LD203, Kokuto Kagaku) E)4-Hydroxy butyl acrylate (4-HBA, OSAKA ORGANIC CHEMICAL) F) Phenoxy ethyl acrylate (M140, Miwon Specialty Chemical) G)Iodonium, (4-methylphenyl)[4-(2-methylpropyl)phenyl]-, hexafluorophosphate(1-)(Irgacure 250, Basf) H)Diphenyl-4-(phenylthio)phenyl sulfonium hexafluoroantimonate (CPI-101A, San-Apro) I) Anthracene sensitizer (UVS-1331, Kawasaki Kasei) J) Naphthalene sensitizer (UVS-2171, Kawasaki Kasei) K)2,4-Diethylthioxanthone (DETX-S, Nipponkayaku) L) Phosphine oxide type PI (Omnirad 819, IGM)

[0158] [Table 2]

[0159] As shown in Table 2, the polarizing plates of the examples can sufficiently prevent iodine eluted from the polarizer from penetrating into the retardation layer after long-term storage at high temperature and humidity. The polarizing plates of the examples had high transfer rates and reaction conversion rates, and therefore had high peel strength between the retardation layer, which has a light transmittance of 1.0% or less in the UVA wavelength range, and the polarizer or protective layer.

[0160] 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]

[0161] 10 polarized photons 20 Upper protective layer 30 First layer 40 First phase difference layer

Claims

1. The polarizer includes a first adhesive layer and a first retardation layer sequentially stacked on a lower surface of the polarizer, The first retardation layer has a light transmittance of 1.0% or less in the UVA wavelength region, the first adhesive layer comprises a cured product of a non-(meth)acrylic composition comprising a curable compound and a photoinitiator; The curable compound contains (A) an epoxy compound, The epoxy compound (A) includes a mixture of a bifunctional alicyclic epoxy compound, a bifunctional aromatic epoxy compound, and a bifunctional aliphatic epoxy compound, The photoinitiator comprises a mixture of an iodonium-based photoacid generator and an anthracene-based photosensitizer, and the anthracene-based photosensitizer is contained in an amount of 0.5 parts by weight or more relative to 100 parts by weight of the curable compound.

2. The polarizing plate according to claim 1 , wherein the first retardation layer is a reverse wavelength dispersion liquid crystal retardation layer.

3. 2. The polarizing plate according to claim 1, wherein the total amount of the bifunctional alicyclic epoxy compound, the bifunctional aromatic epoxy compound, and the bifunctional aliphatic epoxy compound is 95 parts by weight or more per 100 parts by weight of the epoxy compound (A).

4. The polarizing plate according to claim 1 , wherein the bifunctional aliphatic epoxy compound is contained in the curable compound in an excess amount relative to each of the bifunctional alicyclic epoxy compound and the bifunctional aromatic epoxy compound.

5. The polarizing plate according to claim 1 , wherein the bifunctional aromatic epoxy compound comprises at least one of diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and propylene oxide of bisphenol A.

6. 2. The polarizing plate according to claim 1, wherein the bifunctional aliphatic epoxy compound comprises at least one of a substituted or unsubstituted, linear or branched diglycidyl ether compound having a main chain of an alkylene group having 3 or more carbon atoms, and a substituted or unsubstituted diglycidyl ether compound having ethylene oxide or propylene oxide in the molecule.

7. Of 100 parts by weight of the epoxy compound (A), 5 to 30 parts by weight of the bifunctional alicyclic epoxy compound, 5 to 60 parts by weight of the difunctional aromatic epoxy compound, 2. The polarizing plate of claim 1, wherein the bifunctional aliphatic epoxy compound is contained in an amount of 25 to 70 parts by weight.

8. 2. The polarizing plate of claim 1, wherein a weight ratio of the iodonium-based photoacid generator to the anthracene-based photoacid generator is 3:1 to 10:

1.

9. The polarizing plate according to claim 1 , wherein the iodonium-based photoacid generator is a diaryliodonium-based photoacid generator.

10. 2. The polarizing plate according to claim 1, wherein the anthracene-based photosensitizer is a dialkoxyanthracene-based photosensitizer.

11. The polarizing plate of claim 1 , wherein the mixture of the iodonium-based photoacid generator and the anthracene-based photosensitizer is contained in the photoinitiator in an amount of 80% by weight or more.

12. The polarizing plate according to claim 1 , wherein the non-(meth)acrylic composition further comprises a naphthalene-based photosensitizer.

13. The polarizing plate of claim 1 , further comprising a protective layer on the top surface of the polarizer.

14. 14. The polarizer of claim 13, wherein the protective layer comprises a UV absorber.

15. 15. The polarizing plate according to claim 14, wherein the protective layer has a light transmittance of 50% or less in the 380 nm region.

16. An optical display device comprising the polarizing plate according to any one of claims 1 to 15.

Images