KR20230126327A - Polarizing plate and optical display apparatus comprising the same - Google Patents

Abstract

Provided are a polarizing plate and an optical display device comprising the same. The polarizing plate includes a polarizer and a first retardation layer, a second retardation layer, and an adhesive layer sequentially stacked on a lower surface of the polarizer from the polarizer, wherein the adhesive layer includes a mixture of a first compound having a maximum absorption wavelength of 400 to 430 nm, a second compound having a maximum absorption wavelength of 430 to 450 nm, and a third compound having a maximum absorption wavelength of 350 to 400 nm. Therefore, the polarizing plate which provides excellent black visibility is provided.

Description

Polarizing plate and optical display device including the same {POLARIZING PLATE AND OPTICAL DISPLAY APPARATUS COMPRISING THE SAME}

The present invention relates to a polarizing plate and an optical display device including the same.

The organic light emitting display device has excellent screen quality display in a driving state, but has problems in that visibility and contrast are lowered due to reflection of external light in a non-driving state. In order to solve the above problem, a polarizing plate may be used. The polarizing plate may provide an antireflection function by preventing the reflected external light from escaping from the polarizing plate after external light is incident thereon.

The antireflection function can be evaluated by the reflective visibility for external light from the side surface. The reflective visibility on the side surface may be implemented by lowering the reflectance on the side surface. However, there is a problem in that black visibility on the front side may be deteriorated when the reflective visibility on the side is improved. The deterioration of the black luminous feeling means that when light such as a fluorescent lamp is illuminated from the front of the display device panel in a state in which the display device is not driven, the panel screen does not become completely black and stains or mura occur.

The background art of the present invention is disclosed in Japanese Laid-Open Patent Publication No. 2015-010192 and the like.

An object of the present invention is to provide a polarizing plate providing excellent black luminous feeling.

Another object of the present invention is to provide a polarizing plate without precipitation of a light absorbing compound from an adhesive film after being left for a long time in a wide range of environments.

One aspect of the present invention is a polarizing plate.

1. The polarizing plate includes a polarizer and a first retardation layer, a second retardation layer, and an adhesive layer sequentially stacked from the polarizer on a lower surface of the polarizer, and the adhesive layer has a first compound having a maximum absorption wavelength of 400 nm or more and less than 430 nm , a mixture of a second compound having a maximum absorption wavelength of 430 nm or more and less than 450 nm, and a third compound having a maximum absorption wavelength of 350 nm or more and less than 400 nm.

In 2.1, the third compound may have a maximum absorption wavelength of 360 nm to 370 nm.

In 3.1-2, the third compound may be a triazine-based compound.

In 4.1-3, the third compound may be included in an excess amount relative to each of the first compound and the second compound in the adhesive layer.

In 5.1-4, the third compound may be included in an amount of 1% to 10% by weight in the adhesive layer.

In 6.1-5, the first compound may be contained in an amount of 0.01% to 0.5% by weight of the adhesive layer.

In 7.1-6, the first compound may be merocyanine-based.

In 8.1-7, the second compound may be contained in an amount of 0.001% to 0.2% by weight of the adhesive layer.

In 9.1-8, the second compound may be a merocyanine-based compound.

In 10.1-9, all of the first compound, the second compound, and the third compound may be included in an amount of 3% to 15% by weight of the adhesive layer.

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

The optical display device includes the polarizing plate of the present invention.

The present invention provides a polarizing plate providing excellent black visibility.

The present invention provides a polarizing plate without precipitation of a light absorbing compound from an adhesive film after being left in a wide range of environments for a long period of time.

With reference to the accompanying examples, the present invention will be described in detail so that those skilled in the art can easily practice it. This invention may be embodied in many different forms and is not limited to the embodiments set forth herein.

In the present specification, "in-plane retardation (Re)" is represented by the following formula A, "thickness direction retardation (Rth)" is represented by the following formula B, and "biaxiality (NZ)" can be represented by the following formula C there is:

[Equation A]

Re = (nx - ny) x d

[Equation B]

Rth = ((nx + ny)/2 - nz) x d

[Equation C]

NZ = (nx - nz)/(nx - ny)

(In the above formulas A to C, nx, ny, nz are the refractive indices in the slow axis direction, the fast axis direction, and the thickness direction of the optical element at the measurement wavelength, respectively, and d is the thickness of the optical element (unit: nm)). In Formulas A to C, the measurement wavelength may be 450 nm, 550 nm or 650 nm.

In this specification, "short wavelength dispersion" is Re (450) / Re (550), and "long wavelength dispersion" is Re (650) / Re (550). Re(450), Re(550), and Re(650) mean in-plane retardation (Re) at wavelengths of 450 nm, 550 nm, and 650 nm of the retardation layer alone or the retardation layer stack, respectively.

In this specification, “regular wavelength dispersion” means that Re(450)/Re(550) > Re(650)/Re(550).

In the present specification, the "maximum absorption wavelength (λmax)" of a compound means a wavelength at which the maximum absorbance appears when the absorbance is measured for a solution of the compound having a concentration of 10 ppm in methyl ethyl ketone. The maximum absorbance can be measured according to methods known to those skilled in the art.

In this specification, “(meth)acryl” means an acryl and/or methacrylic.

In the present specification, when describing a numerical range, "X to Y" means "X or more and Y or less" (X ≤ and ≤ Y).

The present invention provides a polarizing plate that provides excellent black visibility and provides an effect of preventing precipitation of a light absorbing compound from an adhesive layer after being left for a long time under a wide range of conditions. The polarizing plate may be laminated on a panel for a light emitting display device and used as a polarizing plate for antireflection. The polarizing plate may provide the aforementioned effect while providing an antireflection effect by lowering the reflectance at the side surface.

As will be described below, the polarizer may have a first retardation layer and a second retardation layer, thereby reducing reflectance of external light on the side surface. The polarizing plate may provide an excellent appearance by preventing black luminous deterioration when external light is irradiated from the front side without precipitation of a light absorbing compound after being left for a long period of time without affecting reflectance on the side surface. In particular, the polarizing plate of the present invention provides an adhesive layer that is laminated on the lower surfaces of the first retardation layer and the second retardation layer described below and provides the above effects. To this end, the polarizing plate includes a mixture of a first compound, a second compound, and a third compound having a maximum absorption wavelength in a specific range described below in the adhesive layer.

The polarizing plate of the present invention includes a polarizer and a first retardation layer, a second retardation layer, and an adhesive layer sequentially stacked from the polarizer on a lower surface of the polarizer, and the adhesive layer has a maximum absorption wavelength of 400 nm or more. A mixture of a first compound having a maximum absorption wavelength of less than 430 nm, a second compound having a maximum absorption wavelength of 430 nm or more and less than 450 nm, and a third compound having a maximum absorption wavelength of 350 nm or more and less than 400 nm.

The 'lower surface of the polarizer' is an initial emission surface on which external light is incident on the polarizer and then emitted from the polarizer, or a surface on which light emitted from the light emitting element of the light emitting display device is incident on the polarizer.

A protective film may be further laminated on the upper surface and the lower surface of the polarizer, respectively. The protective film may have a different retardation or material than that of the first retardation layer and the second retardation layer.

Hereinafter, a polarizing plate according to an embodiment of the present invention will be described.

adhesive layer

The adhesive layer has a function of adhering the polarizing plate of the present invention to a panel for a light emitting display device, but contains the first compound, the second compound, and the third compound described below, so that the front surface without affecting the reduction of reflectance on the side surface. It can provide an excellent appearance by preventing black luminous deterioration caused by external light.

Both the first compound and the second compound are included in the adhesive layer to block blue light, thereby improving screen quality, and using a relatively small amount of them can improve black visibility.

The first compound is a light absorbing compound and has a maximum absorption wavelength of 400 nm or more and less than 430 nm, and the second compound is a light absorbing compound and has a maximum absorption wavelength of 430 nm or more and less than 450 nm. In the maximum absorption wavelength range, it is possible to improve screen quality by blocking blue light, and to solve the problem of precipitation and provide an effect of improving black luminous feeling by using them in parallel.

The first compound may be included in an amount of 0.01 wt % to 0.5 wt %, preferably 0.05 wt % to 0.3 wt %, in the adhesive layer. Within the above range, it may not be precipitated from the adhesive layer or interfere with light transmission, and screen quality may be improved.

The first compound may be a solid light absorbing compound at room temperature (eg, 23° C.).

The type of the first compound is not limited as long as it can produce the maximum absorption wavelength range. For example, the first compound may be a dye, pigment, or light absorber having the maximum absorption wavelength range. Specifically, the first compound may include one or more of merocyanine, cyanine, azo, and porphyrin compounds. Preferably, the first compound may be a merocyanine-based dye. In this case, the black luminous feeling can be increased without affecting light transmittance in other wavelength ranges.

The second compound may be included in an amount of 0.001 wt % to 0.2 wt %, preferably 0.005 wt % to 0.1 wt %, in the adhesive layer. Within the above range, it may not be precipitated from the adhesive layer or interfere with light transmission, and screen quality may be improved.

The second compound may be a solid light absorbing compound at room temperature (eg, 23° C.).

The type of the second compound is not limited as long as it can produce the maximum absorption wavelength range. For example, the second compound may be a dye, pigment, or light absorber having the maximum absorption wavelength range. For example, the second compound may include one or more of merocyanine, cyanine, azo, and porphyrin compounds. Preferably, the second compound may be a merocyanine-based dye. In this case, the black luminous feeling can be increased without affecting light transmittance in other wavelength ranges.

The pressure-sensitive adhesive layer includes the first compound and the second compound, but further contains a third compound to be described below in a wide range of environments, for example, at room temperature (eg, 23° C.); high temperature (eg 85° C.); high temperature and high humidity (eg 60° C. and 95% relative humidity); Even if left at low temperature (eg, -20 ° C) for a long period of time, there is no precipitation of the compound alone or a mixture of the compounds, and furthermore, excellent black visibility can be provided from the front. The third compound described below may also provide the above-described color values a* value and b* value, but must be included in excess, and in this case, the polarizer or the adhesive layer is used in a wide range of environments, for example, room temperature (eg, 23 ° C); high temperature (eg 85° C.); high temperature and high humidity (eg 60° C. and 95% relative humidity); There may be a problem that precipitation may occur when left for a long time at low temperature (eg -20 ° C). In order to provide excellent black visibility from the front, the polarizer has an absolute value of a* value of 0 to 2 (ie, -2 ≤ a* value ≤ 2) and an absolute value of b* value of 0 to 2 (ie, -2 ≤ a* value ≤ 2). -2 ≤ b* value ≤ 2).

The third compound is a light absorbing compound and has a maximum absorption wavelength of 350 nm or more and less than 400 nm. The maximum absorption wavelength of the third compound was selected for the purpose of improving black visibility in the front when the first compound and the second compound each having the above maximum absorption wavelength range were used. In the range of the maximum absorption wavelength, it may be easy to improve black luminous sensation from the front side. Preferably, the third compound may have a maximum absorption wavelength of 360 nm to 380 nm, more preferably 360 nm to 370 nm.

In embodiments, the third compound is included in an excess amount relative to each of the first compound and the second compound in the adhesive layer, and may be included in an amount of 1% to 10% by weight, preferably 3% to 8% by weight in the adhesive layer. . Within this range, it may not be precipitated from the adhesive layer or interfere with light transmission, and the light transmittance at 380 nm of the adhesive layer may be maintained at 0.2% or less, thereby preventing the OLED device from being affected by ultraviolet rays.

The third compound may be a liquid or solid light absorbing compound at room temperature.

The type of the third compound is not limited as long as it can produce the maximum absorption wavelength range. For example, the third compound may be a dye, pigment, or light absorber having the maximum absorption wavelength range. Specifically, the third compound may be a triazine-based compound, a hydroxyphenyl triazine-based compound, a triazole-based compound, or a benzotriazole-based compound. Preferably, the third compound may be a triazine-based compound.

The total amount of the first compound, the second compound, and the third compound may be included in an amount of 3 wt% to 15 wt%, preferably 3.5 wt% to 10 wt%, in the adhesive layer. Within the above range, the effects of the present invention can be obtained without problems due to excessive use, and adhesion to the retardation layer described below can be secured.

The adhesive layer may be formed of a composition for an adhesive layer including a first compound, a second compound, a third compound, and an adhesive resin.

The adhesive resin may include a (meth)acrylic copolymer in consideration of compatibility with the first compound, the second compound, and the third compound, ease of manufacture, and the like. In the following, the (meth)acrylic copolymer is described, but the present invention is not limited thereto.

The (meth)acrylic copolymer may have a glass transition temperature of -80°C to -30°C. Within the above range, adhesion between the polarizing plate and the light emitting device panel may be excellent.

The (meth)acrylic copolymer may have a weight average molecular weight of 500,000 to 2,000,000, preferably 500,000 to 1,500,000. Within this range, formation of the adhesive layer may be facilitated.

The (meth)acrylic copolymer may include a (meth)acrylic copolymer of a monomer mixture containing 60% by weight or more of a (meth)acrylic monomer having a glass transition temperature of -70°C to 0°C. Within this range, it may be easy to secure the glass transition temperature of the (meth)acrylic copolymer. Preferably, the monomer mixture may include 60% to 99% by weight of a (meth)acrylic monomer having a homopolymer glass transition temperature of -70°C to 0°C. The (meth)acrylic monomer having a homopolymer having a glass transition temperature of -70°C to 0°C preferably has a glass transition temperature of -70°C to -10°C of the homopolymer, and is preferably 90% by weight in the monomer mixture. % to 99% by weight.

The (meth)acrylic monomer having a homopolymer glass transition temperature of -70℃ to 0℃ is selected from among mono(meth)acrylates having an alkyl group, mono(meth)acrylates having a hydroxyl group, and mono(meth)acrylates having a carboxylic acid group. There may be more than one species. Preferably, mono(meth)acrylate having an alkyl group may be used for ease of supply and demand and easy securing of glass transition temperature.

The monomer mixture may include a mono(meth)acrylate having an alkyl group. The mono(meth)acrylate having an alkyl group may include (meth)acrylic acid ester having an unsubstituted alkyl group having 1 to 10 carbon atoms. Specifically, the mono (meth) acrylate having an alkyl group is methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate rate, iso-butyl(meth)acrylate, pentyl(meth)acrylate, hexyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, heptyl(meth)acrylate, octyl(meth)acrylate, iso - It may include one or more of octyl (meth) acrylate, nonyl (meth) acrylate, and decyl (meth) acrylate, but is not limited thereto.

The monomer mixture may include a (meth)acrylic monomer having a crosslinkable functional group of at least one of a (meth)acrylic monomer having a hydroxyl group and a (meth)acrylic monomer having a carboxylic acid group. A (meth)acrylic monomer having a crosslinkable functional group may provide adhesive strength through a reaction with a crosslinking agent described below.

The (meth)acrylic monomer having a hydroxyl group is preferably a (meth)acrylic monomer having an alkyl group having 1 to 20 carbon atoms and having at least one hydroxyl group, and 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylic monomer )Acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 1-chloro-2-hydroxypropyl (meth)acrylate may include one or more of the rates. The (meth)acrylic monomer having a carboxylic acid group may include (meth)acrylic acid and the like, but is not limited thereto.

The (meth)acrylic monomer having a crosslinkable functional group may be included in an amount of 1 wt% to 40 wt%, preferably 1 wt% to 10 wt%, in the monomer mixture. Within the above range, it may be easy to secure the adhesive strength of the adhesive layer.

The monomer mixture may further include at least one of a (meth)acrylic monomer having an aromatic group, a (meth)acrylic monomer having an amino group, a (meth)acrylic monomer having an alicyclic group, and a (meth)acrylic monomer having a heteroalicyclic group. there is.

The composition for the adhesive layer may further include a crosslinking agent.

The crosslinking agent crosslinks the (meth)acrylic copolymer, and may include a conventional crosslinking agent. The crosslinking agent may include at least one of isocyanate-based, carbodiimide-based, epoxy-based, metal chelate-based, amine-based, and aziridine-based crosslinking agents. Preferably, a mixture of an isocyanate-based crosslinking agent and a carbodiimide-based crosslinking agent may be included as the crosslinking agent. Isocyanate-based crosslinking agents include toluene diisocyanate (TDI) including hexamethylene diisocyanate (HDI), 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, and the like, 4,4'-methylene diphenyl diisocyanate (MDI ), xylylene diisocyanate (XDI) including 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, etc., hydrogenated toluene diisocyanate, isophorone diisocyanate, 1,3-bisisocyanatomethyl 3 of cyclohexane, tetramethylxylene diisocyanate, 1,5-naphthalene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, trimethylolpropane/toluene diisocyanate trimethylolpropane toluene diisocyanate adducts including monomer adducts, xylylene diisocyanate adducts of trimethylolpropane, triphenylmethane triisocyanate, methylene bistriisocyanate, and the like.

The crosslinking agent may be included in an amount of 0.01 part by weight to 20 parts by weight, for example, 0.01 part by weight to 10 parts by weight, or 0.1 part by weight to 4 parts by weight, based on 100 parts by weight of the (meth)acrylic copolymer. Within the above range, the composition may be crosslinked to form an adhesive layer, and deterioration in transparency due to excessive use may be prevented.

The composition for the adhesive layer may further include a silane coupling agent, a tackifier, and various additives. The type and amount of the silane coupling agent, tackifier resin, and various additives may be appropriately selected within a range known to those skilled in the art. For example, the silane coupling agent is included in an amount of 0.001 part by weight to 1 part by weight based on 100 parts by weight of the (meth)acrylic copolymer, and the adhesive imparting resin is included in an amount of 5 parts by weight to 30 parts by weight based on 100 parts by weight of the (meth)acrylic copolymer. can

The adhesive layer is a pressure sensitive adhesive, and may be prepared by applying a composition for the adhesive layer to a predetermined release film to a predetermined thickness, followed by drying and aging. The adhesive layer may have a thickness of 1 μm to 40 μm, preferably 5 μm to 20 μm. Within this range, it can be used for a polarizing plate.

phase contrast layer

The retardation layer may be laminated on the lower surface of the polarizer to lower the reflectance when external light is incident from the side, thereby providing excellent reflective visibility for external light from the side. The retardation layer may be composed of a single layer, but may include two or more retardation layers having different in-plane retardation at a wavelength of 550 nm in order to increase the effect of improving reflective visibility.

The retardation layer includes a first retardation layer and a second retardation layer sequentially stacked from the polarizer. The first retardation layer and the second retardation layer have different in-plane retardation at a wavelength of 550 nm.

The first retardation layer may have an in-plane retardation of 180 nm to 240 nm at a wavelength of 550 nm. Through this, when combined with the second retardation layer having an in-plane retardation at a wavelength of 550 nm described in detail below, the reflectance at the side surface can be remarkably lowered. Preferably, the first retardation layer may have an in-plane retardation of 180 nm to 235 nm at a wavelength of 550 nm.

The first retardation layer may have a positive wavelength dispersion, a short wavelength dispersion of 1 to 1.1, and a long wavelength dispersion of 0.96 to 1. Within the above range, when used in a polarizing plate, the reflectance may be lowered and the ellipticity may be increased.

The first retardation layer may have a thickness direction retardation of 80 nm to 250 nm, preferably 95 nm to 200 nm, and more preferably 105 nm to 180 nm at a wavelength of 550 nm. Within the above range, there may be an effect of improving lateral reflectance.

The first retardation layer may have a degree of biaxiality of 1 to 1.5, preferably 1 to 1.3, and more preferably 1.1 to 1.3 at a wavelength of 550 nm. Within the above range, there may be an effect of improving lateral reflectance.

The first retardation layer may have a thickness of greater than 0 μm and less than or equal to 70 μm, for example, 20 μm to 70 μm. Within this range, it can be used for optical films.

The first retardation layer may be a non-liquid crystalline film or a liquid crystalline film, but preferably may include a stretched film formed of a non-liquid crystalline optically transparent resin. The "non-liquid crystal film" may refer to a film formed of a material that is not formed of at least one of a liquid crystal monomer, a liquid crystal oligomer, and a liquid crystal polymer, or is not converted into a liquid crystal monomer, liquid crystal oligomer, or liquid crystal polymer by light irradiation. .

For example, the first retardation layer may include a cellulose-based material including triacetyl cellulose, a polyester-based material including polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate, and a cyclic olefin Polymer (COC), cyclic polyolefin (COP), polycarbonate, polyethersulfone, polysulfone, polyamide, polyimide, polyolefin, polyarylate, polyvinyl alcohol, polyvinyl chloride It may be a film made of one or more types of resins among the resin-based and polyvinylidene chloride-based. Preferably, the first retardation layer may include a cyclic polyolefin (COP)-based film in that it is easy to secure the wavelength dispersion.

The second retardation layer may have an in-plane retardation of 70 nm to 120 nm at a wavelength of 550 nm. Through this, when combined with the first retardation layer, as an antireflection layer, it is possible to significantly lower the reflectance on the side surface and increase the ellipticity on the side surface. Preferably, the second retardation layer may have an in-plane retardation of 80 nm to 115 nm or 80 nm to 110 nm at a wavelength of 550 nm.

The second retardation layer may have a positive wavelength dispersion, a short wavelength dispersion of 1 to 1.15, and a long wavelength dispersion of 0.94 to 1. Within the above range, the difference in wavelength dispersion compared to the first retardation layer is reduced, and the degree of circular polarization for each wavelength is increased, thereby improving reflection performance.

The second retardation layer may have a thickness direction retardation of -250 nm to -50 nm at a wavelength of 550 nm, preferably -150 nm to -60 nm. Within the above range, the degree of circular polarization on the side surface may be increased, which may have an effect on reflectance on the side surface.

The second retardation layer may have a degree of biaxiality of -2 to -0.1, preferably -1.5 to -0.1 at a wavelength of 550 nm. Within the above range, the degree of circular polarization on the side surface is improved, so that the effect of lowering the reflectance on the side surface can be obtained.

The second retardation layer may have a thickness of greater than 0 μm and less than or equal to 10 μm, for example, 1 μm to 10 μm. Within the above range, the effect of thinning the optical film can be obtained.

The second retardation layer is a non-liquid crystalline retardation layer, and may include, as a main component, preferably at least one of a polystyrene-based polymer and a cellulose-based polymer. In the present invention, the second retardation layer is preferably formed of a composition containing at least one of a polystyrene-based polymer and a cellulose-based polymer. Preferably, the polymer has a halogen, and the halogen may be fluorine.

In this specification, 'polymer' is used as a meaning including an oligomer, polymer, or resin. The "main component" means a component included in 95% by weight or more, specifically, 95% by weight to 99% by weight based on weight% in the second retardation layer.

The polystyrene-based polymer may include repeating units represented by Formula 1 below:

[Formula 1]

(In Formula 1,

is the connection site,

R ¹ , R ² , R ³ are each independently a hydrogen atom, an alkyl group, a substituted alkyl group, or a halogen;

each R is independently an alkyl, substituted alkyl, halogen, hydroxy, carboxy, nitro, alkoxy, amino, sulfonate, phosphate, acyl, acyloxy, phenyl, alkoxycarbonyl, cyano group;

n is an integer from 0 to 5).

In one embodiment, in Formula 1, at least one of R ¹ , R ² , and R ³ may be halogen and/or at least one R may be halogen. Halogen means fluorine (F), Cl, Br or I, preferably F.

The halogen-containing polystyrene-based polymer includes, for example, at least one of 1-(2,2-difluoroethenyl)-2-fluorobenzene and 1', 2', 2'-trifluorostyrene. It can be formed by polymerizing a mixture. The mixture may further include styrene.

The cellulose-based polymer may include at least a unit in which at least some of the hydroxyl groups [C2 hydroxyl group, C3 hydroxyl group, or C6 hydroxyl group] of sugar monomers constituting cellulose are substituted with acyl groups or ether groups. That is, the cellulose-based polymer may include at least one of a cellulose ester-based polymer and a cellulose ether-based polymer.

For example, a cellulose-based polymer is cellulose containing at least a unit in which at least some of the hydroxyl groups [C2 hydroxyl group, C3 hydroxyl group, or C6 hydroxyl group] of sugar monomers constituting cellulose are substituted with acyl groups, as shown in Formula 2 below. An ester-based polymer may be included: In this case, the acyl group may be substituted or unsubstituted.

[Formula 2]

(In Formula 2, n is an integer of 1 or more)

Substituents for cellulose esters or acyl groups are halogen, nitro, alkyl (e.g., alkyl groups having 1 to 20 carbon atoms), alkenyl (e.g., alkenyl groups having 2 to 20 carbon atoms), cycloalkyl (e.g., 3 to 20 carbon atoms), respectively. cycloalkyl group of 10), aryl (eg, aryl group of 6 to 20 carbon atoms), heteroaryl (eg, aryl group of 3 to 10 carbon atoms), alkoxy (eg, alkoxy group of 1 to 20 carbon atoms), acyl , It may include one or more of halogen-containing functional groups. Substituents may be the same or different.

As known to those skilled in the art, the "acyl" means R-C(=0)-*(* is a linking symbol, R is an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl having 6 to 20 carbon atoms, or arylalkyl having 7 to 20 carbon atoms). The "acyl" is attached to the ring of cellulose via an ester linkage (through an oxygen atom) in cellulose.

Each of the above "alkyl", "alkenyl", "cycloalkyl", "aryl", "heteroaryl", "alkoxy", and "acyl" is a halogen-free non-halogen type for convenience. The composition for the second retardation layer may include the cellulose ester-based alone or a mixture of the cellulose ester-based.

The "halogen" means fluorine (F), Cl, Br or I, preferably F.

The "halogen-containing functional group" is an organic functional group containing one or more halogens, and may include an aromatic, aliphatic or alicyclic functional group. For example, the halogen-containing functional group is a halogen-substituted C1-C20 alkyl group, a halogen-substituted C2-C20 alkenyl group, a halogen-substituted C2-C20 alkynyl group, a halogen-substituted C3-C10 A cycloalkyl group, a halogen-substituted C1-C20 alkoxy group, a halogen-substituted acyl group, a halogen-substituted C6-C20 aryl group, or a halogen-substituted C7-C20 arylalkyl group, but , but not limited thereto.

The "halogen substituted acyl group" is R'-C(=O)-*(* is a linking symbol, R' is a halogen-substituted C 1 to C 20 alkyl group, a halogen-substituted C 3 to C 20 cycloalkyl , halogen-substituted aryl having 6 to 20 carbon atoms or halogen-substituted arylalkyl having 7 to 20 carbon atoms). The "halogen substituted acyl group" is bonded to the ring of cellulose via an ester bond (through an oxygen atom) in cellulose.

The cellulose ester-based polymer may be prepared by a conventional method known to those skilled in the art or purchased and used as a commercially available product. For example, a cellulose ester-based polymer having acyl as a substituent is obtained by reacting trifluoroacetic acid or trifluoroacetic anhydride with a sugar monomer or a polymer of sugar monomers constituting cellulose of the above formula (2), or trifluoroacetic acid or trifluoroacetic acid. Reacting fluoroacetic anhydride followed by further reaction of an acylating agent (e.g., an anhydride of a carboxylic acid, or carboxylic acid), or reacting trifluoroacetic acid or trifluoroacetic anhydride and an acylating agent together It can then be prepared by polymerization.

The laminate of the first retardation layer and the second retardation layer may be obtained by manufacturing the first retardation layer and the second retardation layer and then combining them, or by applying a composition for the second retardation layer to an unstretched or partially stretched film for the first retardation layer. It may be prepared by forming a coating film and stretching the entire film and the coating film.

polarizer

The polarizer may provide an antireflection effect by polarizing incident light in one direction and emitting it.

The polarizer may include a conventional polarizer known to those skilled in the art. For example, the polarizer may include at least one of a polarizer obtained by dyeing polyvinyl alcohol with a dichroic dye such as iodine, and a polyene-based polarizer prepared by dehydrating polyvinyl alcohol. The polarizer may have a thickness of 0.5 μm to 30 μm, for example, 1 μm to 20 μm.

protective film

The protective film may include at least one of an optically transparent resin film and an optically transparent protective layer. The resin film and the protective layer may be used by adopting those commonly used in the field of polarizing plates, respectively.

Hereinafter, an optical display device according to an exemplary embodiment of the present invention will be described. The optical display device includes the adhesive layer of the present invention or the polarizing plate of the present invention.

The optical display device may be an organic light emitting device, an inorganic light emitting device, or a light emitting device display device including organic/inorganic light emitting devices.

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, this is presented as a preferred example of the present invention and cannot be construed as limiting the present invention by this in any sense.

Preparation Example: Preparation of (meth)acrylic copolymer

98 parts by weight of n-butyl acrylate, 2 parts by weight of acrylic acid, and 150 parts by weight of ethyl acetate were added to a 1L reactor in which nitrogen gas was refluxed and a cooling device was installed to facilitate temperature control, and nitrogen gas was added for 1 hour while stirring to react. After replacing oxygen in the plane, the temperature of the reactor was maintained at 70°C. 0.06 parts by weight of 2,2'-azobisisobutyronitrile was added as an initiator and reacted for 8 hours to prepare a (meth)acrylic copolymer-containing solution. The (meth)acrylic copolymer had a glass transition temperature of -42°C and a weight average molecular weight of 1,000,000. Ethyl acetate was further added to prepare a solution containing a (meth)acrylic copolymer having a solid content of 17% by weight.

Specific specifications of the dyes used in the Examples and Comparative Examples are as follows.

(A1) First compound: merocyanine-based dye (Yamada Chemical Co., FDB-001) with a maximum absorption wavelength (λmax) of 420 nm

(A2) 2nd compound: λmax 438 nm merocyanine dye (Yamada Chemical Co., FDB-003)

(A3) Third compound: λmax 360 nm triazine-based UV absorber (BASF, TINUVIN-477)

Example 1

A polyvinyl alcohol-based film (PS#60, Kuraray, Japan, thickness before stretching: 60 μm) was stretched 6 times in an aqueous iodine solution at 55° C. to prepare a polarizer (thickness: 12 μm) with a light transmittance of 43%.

A composition for forming a second retardation layer on the lower surface of a cyclic polyolefin (COP)-based film (Zeon Company, ZD film) stretched in a 45° direction based on MD [cellulose ester-based polymer (with trifluoroacetyl) A non-liquid crystalline composition containing] was applied to form a coating film for forming the second retardation layer. The cellulose ester-based polymer was prepared by adding trifluoroacetic acid and trifluoroacetic anhydride to unsubstituted cellulose, followed by reaction and polymerization. After drying the coating film, the laminate of the coating film and the COP-based film is stretched at a stretching ratio of 1.5 times at 135 ° C. based on the MD of the COP-based film, so that the first retardation layer (positive wavelength dispersion, in-plane retardation at a wavelength of 550 nm is 202 nm) ) and a second retardation layer (regular wavelength dispersion, in-plane retardation at a wavelength of 550 nm is 92 nm).

An adhesive for polarizing plate was applied to the upper surface of the prepared polarizer, and a TAC film (thickness: 27 μm, Konica Minolta Co., Ltd.) was laminated as a protective film on the upper surface of the polarizer, and an adhesive for polarizing plate was applied to the lower surface of the polarizer. The laminate of the first retardation layer and the second retardation layer was laminated on the lower surface of the , and UV was irradiated in the direction of the protective film from the lower surface of the second retardation layer.

Based on the solid content of 100 parts by weight of the (meth)acrylic copolymer prepared in Preparation Example, 2.118 parts by weight of NCO crosslinking agent (L-45, Soken, 45% solid content), 0.235 parts by weight of carbodiimide crosslinking agent (V05S), silane coupling agent (KBM) -403, Shinyetsu) 0.353 parts by weight, Tackifier (CK500L, NCI) 15 parts by weight, 0.1 parts by weight of the first compound, 0.05 parts by weight of the second compound, 3.9 parts by weight of the third compound, and 25 parts by weight of methyl ethyl ketone for the adhesive layer After preparing the composition and applying it to a PET release film, it was dried in an oven at 90° C. for 4 minutes to prepare an adhesive layer having a thickness of 13 μm. A polarizing plate was manufactured by laminating the prepared adhesive layer to the lower surface of the second retardation layer.

Examples 2 to 4

In Example 1, a polarizing plate was prepared in the same manner as in Example 1, except that the contents of the first compound, the second compound, and the third compound were changed as shown in Table 1 below. In Table 1 below, units are parts by weight, and '-' means that the corresponding component is not included.

Comparative Examples 1 to 5

In Example 1, a polarizing plate was prepared in the same manner as in Example 1, except that the contents of the first compound, the second compound, and the third compound were changed as shown in Table 1 below.

The physical properties of Table 1 below were evaluated for the polarizing plates prepared in Examples and Comparative Examples.

(1) Black luminosity (unit: none): An optical display module was manufactured by attaching the polarizing plate of Example or Comparative Example to the upper surface of the organic light emitting device panel via the adhesive layer. For the manufactured optical display module, light was irradiated from the polarizer side at a frontal angle of 0.05° using a spectrophotometer DMS 803 (Instrument Systems Co.), and then the light reflected from the optical display module and leaked out was measured and CIE 1976 The black luminous color value a* value and b* value at 0° front were measured according to the year a*b* standard.

(2) Whether or not to precipitate (unit: none): An adhesive layer was prepared in the same manner as in Examples and Comparative Examples, and the prepared adhesive layer was cut into a size of 20 cm x 20 cm in width x length, and then heated at 23 ° C; 85°C; 60° C. and 95% relative humidity; After storing for 2000 hours each in a total of four chambers at -20 ° C, it was visually confirmed whether or not the compound was crystallized and precipitated from the adhesive layer. In the above four conditions, when any one precipitated, it was evaluated as X, and when it did not precipitate at all, it was evaluated as ○.

Example comparative example One 2 3 4 One 2 3 4 5 (A1) 0.1 0.1 0.15 0.05 - - - 0.2 - (A2) 0.05 0.01 0.05 0.07 - - 0.05 - 0.1 (A3) 3.9 6.5 7.5 7.5 - 3.9 - 3.7 3.8 black time sense a* 0.2 0.2 0.1 0.1 2.5 2.5 2.2 0.2 0.2 b* -1.1 -1.8 -One -1.5 -5 -4.5 -2.5 -1.3 -1.1 Precipitation ○ ○ ○ ○ ○ ○ ○ X X

As shown in Table 1, the absolute values of the color value a* value and the color value b* value of the polarizer of the present invention are 0 to 2, respectively, so that although not shown in Table 1, it can provide excellent black visibility even from the front. can In addition, as shown in Table 1, the polarizing plate of the present invention did not precipitate the light absorbing compound from the adhesive film after being left for a long time in a wide range of environments.

On the other hand, Comparative Examples 1 to 5, which do not contain the first compound, the second compound, and the third compound, cannot obtain all of the effects of the present invention described above.

Simple modifications or changes of the present invention can be easily performed by those skilled in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

Claims (11)

A polarizer and a first retardation layer, a second retardation layer, and an adhesive layer sequentially stacked from the polarizer on a lower surface of the polarizer,
The adhesive layer includes a mixture of a first compound having a maximum absorption wavelength of 400 nm or more and less than 430 nm, a second compound having a maximum absorption wavelength of 430 nm or more and less than 450 nm, and a third compound having a maximum absorption wavelength of 350 nm or more and less than 400 nm. A polarizing plate.
The polarizing plate of claim 1, wherein the third compound has a maximum absorption wavelength of 360 nm to 370 nm.
The polarizing plate of claim 1, wherein the third compound is a triazine-based compound.
The polarizing plate of claim 1 , wherein the third compound is included in an excessive amount relative to each of the first compound and the second compound in the adhesive layer.
The polarizing plate of claim 1, wherein the third compound is included in an amount of 1 wt % to 10 wt % in the adhesive layer.
The polarizing plate of claim 1, wherein the first compound is contained in an amount of 0.01% to 0.5% by weight in the adhesive layer.
The polarizing plate of claim 1, wherein the first compound is merocyanine-based.
The polarizing plate of claim 1, wherein the second compound is contained in an amount of 0.001% to 0.2% by weight in the adhesive layer.
The polarizing plate of claim 1, wherein the second compound is a merocyanine-based compound.
The polarizing plate of claim 1, wherein the first compound, the second compound, and the third compound are all contained in an amount of 3% to 15% by weight in the adhesive layer.
An optical display device comprising the polarizing plate of any one of claims 1 to 10.