KR20230135888A - Adhesive composition for polarizing plate, polarizing plate and optical display apparatus - Google Patents

Abstract

A polarizing plate comprising an epoxy-based compound, a (meth)acrylate-based compound, a photocationic initiator, and a photosensitizer, wherein the photosensitizer includes a mixture of a thioxanthone-based photosensitizer and an anthracene-based photosensitizer. Adhesive compositions, polarizers, and optical display devices are provided.

Description

Adhesive composition for polarizing plate, polarizing plate and optical display device {ADHESIVE COMPOSITION FOR POLARIZING PLATE, POLARIZING PLATE AND OPTICAL DISPLAY APPARATUS}

The present invention relates to an adhesive composition for a polarizing plate, a polarizing plate, and an optical display device.

The organic light emitting display device is a self-emitting display device and does not need to be provided with a separate polarizer like a liquid crystal display device. However, by providing a retardation film having a retardation within a predetermined range between the polarizer and the organic light emitting device panel, it is possible to improve screen quality by preventing reflection of external light by circularly polarizing linearly polarized light incident from the polarizer.

The polarizer includes a polarizer, a protective layer laminated on the upper surface of the polarizer, and a retardation film laminated on the lower surface of the polarizer. The retardation film may be a film obtained by stretching an unstretched film formed of a composition containing a polymer resin or a liquid crystal retardation film. Generally, in order to increase the anti-reflection effect, the retardation film has reverse wavelength dispersion.

The liquid crystal retardation film with reverse wavelength dispersion is thin, so it is advantageous for thinning compared to the retardation film made of polymer resin. However, some of the liquid crystal retardation films with reverse wavelength dispersion have low UV transmission characteristics that block most UV compared to liquid crystal retardation films with forward wavelength dispersion. Due to this, UV is not properly transmitted to the adhesive layer coating film through the liquid crystal retardation film with reverse wavelength dispersion, and the adhesive layer coating film is not properly cured, which may result in poor adhesion between the polarizer and the liquid crystal retardation film. However, when UV is irradiated through the protective layer laminated on the upper surface of the polarizer, the UV reaching the adhesive layer coating inevitably becomes lower due to the UV absorber contained in the protective layer.

On the other hand, since the polarizer is manufactured by dyeing iodine, etc., if the polarizer is left at high temperature and high humidity for a long period of time, the iodine, etc. may discolor from the polarizer and iodine may escape from the polarizer. Iodine released in this way can seep into the liquid crystal retardation film and cause problems with the entire function of the polarizer.

The background technology of the present invention is described in Japanese Patent Publication No. 2014-032270.

The purpose of the present invention is to provide an adhesive composition for a polarizing plate that implements an adhesive layer with excellent adhesion between a polarizer and a liquid crystal retardation film in a wide range of environments.

Another object of the present invention is to provide an adhesive composition for a polarizing plate that implements an adhesive layer that prevents discoloration from the polarizer after being left at high temperature and high humidity for a long period of time.

Another object of the present invention is to provide a polarizer that has excellent adhesion between a polarizer and a liquid crystal retardation film in a wide range of environments and prevents discoloration from the polarizer after being left for a long period of time at high temperature and high humidity, and an optical display device including the same.

One aspect of the present invention is an adhesive composition for a polarizing plate.

The adhesive composition for a polarizing plate includes an epoxy-based compound, a (meth)acrylate-based compound, a photocationic initiator, and a photosensitizer, and the photosensitizer includes a mixture of a thioxanthone-based photosensitizer and an anthracene-based photosensitizer. do.

Another aspect of the present invention is a polarizer.

The polarizing plate includes a polarizer and a liquid crystal retardation film laminated on a lower surface of the polarizer, the polarizer and the liquid crystal retardation film are laminated by an adhesive layer, and the adhesive layer includes a thioxanthone-based photosensitizer and an anthracene-based photosensitizer. Contains mixtures.

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 an adhesive composition for a polarizing plate that implements an adhesive layer with excellent adhesion between a polarizer and a liquid crystal retardation film in a wide range of environments.

The present invention provides an adhesive composition for a polarizing plate that implements an adhesive layer that prevents discoloration from the polarizer after being left for a long period of time at high temperature and high humidity.

The present invention provides a polarizer that has excellent adhesion between a polarizer and a liquid crystal retardation film in a wide range of environments and prevents discoloration from the polarizer after being left for a long period of time at high temperature and high humidity, and an optical display device including the same.

1 is a cross-sectional view of a polarizer according to an embodiment of the present invention.
Figure 2 is a schematic diagram showing a schematic explanation for evaluating decolorization (iodine loss) of a polarizer.

With reference to the attached drawings, the embodiments will be described in detail so that those skilled in the art can easily implement the present invention. The present invention may be implemented in many different forms and is not limited to the embodiments described herein. In order to clearly explain the present invention in the drawings, parts not related to the description are omitted, and identical or similar components are given the same reference numerals throughout the specification. The length and thickness of each component in the drawings are shown to explain the present invention, and the present invention is not limited to the lengths and thicknesses shown in the drawings.

In this specification, “upper” and “lower” are based on the drawings, and are not necessarily fixed as upper and lower, and “upper” may change to “lower” and “lower” to “upper” depending on the viewing angle. You can.

In this specification, “in-plane retardation (Re)” can be expressed by the following formula A:

<Formula A>

Re = (nx - ny) x d

(In the above formula A, nx and ny are the refractive index in the slow axis direction and the fast axis direction of the liquid crystal retardation film at a wavelength of 550 nm, respectively, and d is the thickness of the liquid crystal retardation film (unit: nm) )).

In this specification, “light emitting device” includes an organic or inorganic light emitting device, and includes light emitting materials such as LED (light emitting diode), OLED (organic light emitting diode), QLED (quantum dot light emitting diode), and phosphor. It may mean a device.

The inventor of the present invention provided an adhesive composition for a polarizer that has excellent adhesion between a polarizer and a liquid crystal retardation film in a wide range of environments and implements an adhesive layer that prevents discoloration from the polarizer after being left for a long period of time at high temperature and high humidity. The adhesive composition for a polarizing plate of the present invention is used to bond a polarizer and a liquid crystal retardation film.

In one embodiment, the peeling force (initial peeling force) between the polarizer and the liquid crystal retardation film in the polarizer-adhesive layer-liquid crystal retardation film laminate may be 100gf/25mm or more, for example, 100gf/25mm to 500gf/25mm. Within the above range, the reliability and durability of the polarizer may be excellent.

In one embodiment, after the polarizer-adhesive layer-liquid crystal retardation film laminate is left at 60° C. and 95% relative humidity for 3 days, the peeling force between the polarizer and the liquid crystal retardation film is 100 gf/25mm or more, for example, 100 gf/25mm. It can be from 500gf/25mm. Within the above range, the reliability and durability of the polarizer may be excellent.

The adhesive composition for a polarizing plate includes an epoxy-based compound, a (meth)acrylate-based compound, a photocationic initiator, and a photosensitizer, and the photosensitizer includes a mixture of a thioxanthone-based photosensitizer and an anthracene-based photosensitizer. do.

As will be explained below, the photosensitizer is contained in the adhesive composition in a relatively small amount compared to the epoxy-based compound and (meth)acrylate-based compound, which are photocurable components. However, the photosensitizer can provide excellent adhesion between the polarizer and the liquid crystal retardation film in a wide range of environments by containing both a thioxanthone-based photosensitizer and an anthracene-based photosensitizer. In particular, a mixture of a thioxanthone-based photosensitizer and an anthracene-based photosensitizer is contained in an adhesive composition used to bond a liquid crystal retardation film with low UV transmission properties and a polarizer, allowing it to be used in a wide range of environments between the polarizer and the liquid crystal retardation film. was selected for its excellent adhesion. In addition, the photosensitizer can prevent iodine from discoloring from the polarizer after the polarizer is left at high temperature and humidity for a long period of time, or prevent iodine discolored from the polarizer from seeping into the liquid crystal retardation film.

Hereinafter, the composition of one embodiment of the present invention will be described in detail.

photosensitizer

The photosensitizer essentially includes a mixture of a thioxanthone-based photosensitizer and an anthracene-based photosensitizer. Adhesive compositions in which the photosensitizer is a thioxanthone-based photosensitizer alone or a thioxanthone-based photosensitizer containing a photosensitizer other than an anthracene-based photosensitizer have poor sensitization effect with a photocationic initiator and are not effective in sensitizing the anthracene-based photosensitizer. There may be a problem in that the adhesion between the polarizer and the liquid crystal retardation film is lowered after high temperature and high humidity due to the lack of post-curing ability due to the absence of the film. Adhesive compositions containing an anthracene-based photosensitizer alone or an anthracene-based photosensitizer plus a photosensitizer other than a thioxanthone-based photosensitizer lack direct sensitizing effect on the photocationic initiator, resulting in insufficient adhesion and high temperature and humidity. There may be a problem in preventing iodine decolorization.

In one embodiment, a mixture of a thioxanthone-based photosensitizer and an anthracene-based photosensitizer is a combination of an epoxy-based compound and a (meth)acrylate-based compound described below, and it is easy to implement the effect of the present invention. The effect can be further improved.

The mixture of thioxanthone-based photosensitizer and anthracene-based photosensitizer may be included in 90% by weight to 100% by weight, preferably 100% by weight, of the photosensitizer. Within the above range, the effect of the present invention can be effectively achieved.

The photosensitizer may be included in an amount of 0.5 parts by weight to 10 parts by weight, preferably 1 part by weight to 5 parts by weight, based on a total of 100 parts by weight of the following epoxy compounds and the following (meth)acrylate compounds. Within the above range, the effect of the present invention can be easily implemented and the effect of the present invention can be further improved.

The weight ratio of thioxanthone-based photosensitizer:anthracene-based photosensitizer in the mixture may be 1:0.1 to 1:10. Within the above range, the above-described effects of the present invention can be achieved. Preferably, the weight ratio may be 1:0.2 to 1:5, more preferably 1:0.3 to 1:3, and within this range, the above-described effect of the present invention can be significantly improved, and the high It can be effective in suppressing adhesion and discoloration of iodine at high temperature and high humidity.

Preferably, the anthracene-based photosensitizer may include an alkoxy group-containing anthracene-based photosensitizer. For example, the anthracene-based photosensitizer may be an anthracene-based compound represented by the following formula (1):

[Formula 1]

(In Formula 1 above,

R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , R ₈ , R ₉ , R ₁₀ are each independently hydrogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, substituted or unsubstituted Ringed alkoxy group having 1 to 20 carbon atoms, substituted or unsubstituted mono or polyalkyleneoxy group having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, substituted or unsubstituted 6 to 20 carbon atoms Aryl group, substituted or unsubstituted arylalkyl group having 7 to 20 carbon atoms, halogen, hydroxyl group, amino group (-NH ₂ ) or thiol group (-SH),

At least one of R ₁ , R ₂ , R ₃ , R ₄ , R 5 , R ₆ , R ₇ , R ₈ , R ₉ , and R ₁₀ is _a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms).

Preferably, at least two of R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , R ₈ , R ₉ , and R ₁₀ are substituted or unsubstituted alkoxy groups having 1 to 5 carbon atoms. You can.

In the present specification, 'substituted' in 'substituted or unsubstituted' means that the hydrogen atom of one or more functional groups is an alkyl group with 1 to 5 carbon atoms, an alkoxy group with 1 to 5 carbon atoms, an aryl group with 6 to 10 carbon atoms, or a cyclo with 3 to 10 carbon atoms. It means substitution with an alkyl group, halogen, hydroxyl group, amino group, etc.

For example, anthracene-based photosensitizers include 9,10-dimethoxyanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, 9,10-diisopropoxyanthracene, and 9,10-dibu. Toxyanthracene, 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-butoxypropoxy)anthracene, 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, etc. You can.

Preferably, the anthracene-based photosensitizer is 9,10-dimethoxyanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, 9,10-diisopropoxyanthracene, 9,10-dibu. It may be oxyanthracene, 9,10-dipentyloxyanthracene, 9,10-dihexyloxyanthracene, and more preferably 9,10-dibutoxyanthracene.

The anthracene-based photosensitizer may be included in an amount of 0.1 to 5 parts by weight, preferably 0.5 to 2 parts by weight, based on 100 parts by weight of the epoxy compound. The anthracene-based photosensitizer may be included in an amount of 0.5 parts by weight to 10 parts by weight, preferably 1 part by weight to 8 parts by weight, based on 100 parts by weight of the (meth)acrylate-based compound. Within the above range, the initial reaction of thioxanthone can be appropriately suppressed to effectively delay curing and subsequently increase final curing.

Preferably, the thioxanthone-based photosensitizer may be a thioxanthone-based photosensitizer containing an alkyl group or halogen. For example, the thioxanthone-based photosensitizer may include a compound represented by the following formula (2):

[Formula 2]

(In Formula 2, R ₁ and R ₂ are each independently hydrogen, halogen, or an alkyl group having 1 to 5 carbon atoms).

Specifically, the thioxanthone-based photosensitizer may be one or more of diethyl thioxanthone, isopropyl thioxanthone, chlorothioxanthone, and chloropropoxy thioxanthone. Preferably, the thioxanthone-based photosensitizer may be diethyl thioxanthone.

The thioxanthone-based photosensitizer may be included in an amount of 0.1 to 5 parts by weight, preferably 0.5 to 2 parts by weight, based on 100 parts by weight of the epoxy compound. The anthracene-based photosensitizer may be included in an amount of 0.5 parts by weight to 10 parts by weight, preferably 1 part by weight to 8 parts by weight, based on 100 parts by weight of the (meth)acrylate-based compound. In the above range, UV of a limited wavelength can be effectively absorbed to form an effective three-dimensional polymer structure of epoxy and acrylate through indirect activation of diaryliodide salt.

Photocationic initiator

The photo cationic initiator can photocure the epoxy-based compound and (meth)acrylate-based compound described below along with the above-mentioned photosensitizer.

The photo cationic initiator may include an onium salt of a cation and an anion, which are onium ions. Specific examples of onium ions include diphenyliodonium, 4-methoxydiphenyliodonium, bis(4-methylphenyl)iodonium, bis(4-tert-butylphenyl)iodonium, bis(dodecylphenyl)iodonium, (4) -methylphenyl)[(4-(2-methylpropyl)phenyl)iodonium, such as diaryliodonium, triphenylsulfonium, diphenyl-4-thiophenoxyphenylsulfonium, diphenyl-4-(phenylthio) )Triarylsulfonium such as phenylsulfonium, bis[4-(diphenylsulfonio)-phenyl]sulfide, bis[4-(di(4-(2-hydroxyethyl)phenyl)sulfonio) -phenyl] sulfide, 5-2,4-(cyclopentadienyl)[1,2,3,4,5,6-η]-(methylethyl)-benzene]-iron (1+), etc. You can. Specific examples of anions include tetrafluoroborate (BF ₄ ^- ), hexafluorophosphate (PF ₆ ^- ), hexafluoroantimonate (SbF ₆ ^- ), hexafluoroarsenate (AsF ₆ ^- ), and hexafluoroborate (BF 4 - ). Chloroantimonate (SbCl ₆ ^- ) and the like can be mentioned.

Preferably, the photocationic initiator is diphenyliodonium, 4-methoxydiphenyliodonium, bis(4-methylphenyl)iodonium, bis(4-tert-butylphenyl)iodonium, or bis(dodecylphenyl)iodonium. , (4-methylphenyl)[(4-(2-methylpropyl)phenyl)iodonium, and other onium salts having diaryliodonium or triarylsulfonium, most preferably diaryliodonium salts. The effect of the present invention can be further improved when a photo cationic initiator having a diaryliodonium salt is combined with the photosensitizer.

The photo cationic initiator may be included in an amount of 0.5 parts by weight to 10 parts by weight, for example, 1 part by weight to 6 parts by weight, based on a total of 100 parts by weight of the epoxy compound and the (meth)acrylate compound. Within the above range, the composition for an adhesive layer can be sufficiently cured and there may be no problems such as a decrease in adhesion force or bleed-out of the photo cationic initiator.

Epoxy-based compounds

Epoxy-based compounds can increase adhesion by reacting with a photo-cationic initiator and a photosensitizer initiated by light energy.

The epoxy-based compound may include a mixture of a bifunctional alicyclic epoxy-based compound and an aromatic group-containing glycidyl ether-based compound. The mixture, when combined with the mixture of the thioxanthone-based photosensitizer and anthracene-based photosensitizer of the present invention, has excellent adhesion in a wide range of environments between the polarizer and the liquid crystal retardation film, and forms an adhesive layer that prevents discoloration from the polarizer at high temperature and high humidity. can be implemented. In particular, the mixture was selected to be contained in an adhesive composition used to bond a liquid crystal retardation film with low UV transmission properties and a polarizer, and to provide excellent adhesion between the polarizer and the liquid crystal retardation film in a wide range of environments.

The aromatic group-containing glycidyl ether compound may be included in an amount of 70 to 150 parts by weight, preferably 90 to 130 parts by weight, based on 100 parts by weight of the bifunctional alicyclic epoxy compound. Within the above range, it can be easy to implement the effects of the present invention.

The mixture of the bifunctional alicyclic epoxy compound and the aromatic group-containing bifunctional glycidyl ether compound is 90% to 100% by weight, preferably 95% to 100% by weight, more preferably 95% by weight to 100% by weight of the epoxy compound in the composition. Can be included at 100% by weight. Within the above range, it can be easy to implement the effects of the present invention.

A bifunctional alicyclic epoxy compound may refer to a compound having two epoxidized alicyclic groups. For example, bifunctional alicyclic epoxy compounds include 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexane carboxylate, 3,4-epoxy-6-methylcyclohexylmethyl-3', 4'-epoxy-6'-methylcyclohexanecarboxylate, bis(3,4-epoxy-6-methylcyclohexyl) adipate, bicyclohexyl diepoxide (3,4,3',4'-di It may include, but is not limited to, one or more of epoxy-bicyclohexane), 3,4-Epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate modified epsilon-caprolactone.

The bifunctional alicyclic epoxy compound may be included in an amount of 10 parts by weight to 70 parts by weight, preferably 30 parts by weight to 50 parts by weight, based on a total of 100 parts by weight of the epoxy compound and the (meth)acrylate compound. Within the above range, high adhesion and durability at high temperature and high humidity can be achieved by having a high Tg and modulus after curing.

The aromatic group-containing glycidyl ether compound is a bifunctional diglycidyl ether compound and may contain an aromatic group and two glycidyl ether groups. The “glycidyl ether group” may mean, but is not limited to, a moiety of the following formula (3):

[Formula 3]

(In Formula 3, * is a connection site)

Specifically, the aromatic group-containing glycidyl ether-based compound is bisphenol-based diglycidyl ether, such as resorcinol diglycidyl ether, bisphenol A diglycidyl ether, bisphenol S diglycidyl ether, and bisphenol F diglycidyl ether. It may be a cidyl ether-based compound.

The aromatic group-containing glycidyl ether-based compound may be included in an amount of 10 to 70 parts by weight, preferably 30 to 50 parts by weight, based on a total of 100 parts by weight of the epoxy-based compound and the (meth)acrylate-based compound. In the above range, the characteristic that the reaction rate is relatively slow compared to the cycloaliphatic epoxy can be effectively expressed, thereby increasing the degree of polymerization through additional crosslinking reaction of the pre-polymerized cycloaliphatic epoxy and improving the peeling force through sufficient absorption into the adhered substrate. .

The epoxy-based compound may be included in an amount of 50 to 90 parts by weight, preferably 60 to 80 parts by weight, based on a total of 100 parts by weight of the epoxy-based compound and the (meth)acrylate-based compound. Within the above range, the polymerization of the epoxy can be effectively achieved, ensuring high adhesion, and the water resistance of the polarizer may not be deteriorated.

(meth)acrylate-based compounds

(Meth)acrylate-based compounds are polymerized by a photo cationic initiator and a photosensitizer initiated by light energy, and can react stably by light energy without being inhibited by moisture. The (meth)acrylate-based compound may include (meth)acrylate containing one or more hydroxyl groups.

(meth)acrylate containing one or more hydroxyl groups improves the adhesion at the interface between the polarizer and the liquid crystal retardation film during the curing process, and is capable of chain transfer bonding with the cation-activated epoxy compound, thereby providing excellent adhesion. can do.

(meth)acrylate containing one or more hydroxyl groups is a monofunctional (meth)acrylate, an alkyl group-containing (meth)acrylate having 1 to 20 carbon atoms having one or more hydroxyl groups, and (meth)acrylate containing 3 to 20 carbon atoms having one or more hydroxyl groups. It may include one or more of an alicyclic group-containing (meth)acrylate and an aromatic group-containing (meth)acrylate having 6 to 20 carbon atoms having one or more hydroxyl groups. For example, (meth)acrylates containing one or more hydroxyl groups include 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2- Hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 1,4-cyclohexanedimethanol mono (meth)acrylate, 1-chloro-2-hydroxypropyl (meth)acrylate, Diethylene glycol mono(meth)acrylate, 1,6-hexanediol mono(meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 4-hydroxycyclohexyl (meth)acrylate , 2-hydroxy-3-phenoxybutyl (meth)acrylate, and 4-hydroxycyclohexyl (meth)acrylate, but is not limited thereto.

The (meth)acrylate containing one or more hydroxyl groups is 5 to 80 parts by weight, for example, 5 to 20 parts by weight, 5 out of 100 parts by weight of the total of the epoxy compound and the (meth)acrylate compound. It may be included in an amount of more than 20 parts by weight, 5 to 18 parts by weight, and 10 to 18 parts by weight. In the above range, the curing structure of the adhesive through a fast initial reaction rate contributes to the formation, and the peeling force between the polarizer and the liquid crystal retardation film may not be reduced due to copolymerization through chain transfer bonding with the epoxy polymer.

Preferably, the (meth)acrylate-based compound may further contain an aromatic group-containing (meth)acrylate in addition to one or more hydroxyl group-containing (meth)acrylates. The aromatic group-containing (meth)acrylate does not contain one or more hydroxyl groups. The aromatic group-containing (meth)acrylate may improve the initial reactivity of the composition for an adhesive layer and may also contribute to improving the peeling power of the adhesive layer against the liquid crystal retardation film. The aromatic group-containing (meth)acrylate is a monofunctional or polyfunctional (meth)acrylate, for example, an aryloxy group (e.g., a phenoxy group) having 6 to 20 carbon atoms and an alkyl group having 1 to 5 carbon atoms (meth) ) May contain acrylate. Preferably, the aromatic group-containing (meth)acrylate may include phenoxy ethyl (meth)acrylate.

The aromatic group-containing (meth)acrylate is 20 parts by weight or less, for example, less than 20 parts by weight, 1 to 20 parts by weight, 1 out of 100 parts by weight of the total of the epoxy compound and the (meth)acrylate compound. It may be included in 15 parts by weight or 1 part by weight to 10 parts by weight. Within the above range, it may be easy to improve the adhesion between the polarizer and the liquid crystal retardation film.

The (meth)acrylate-based compound may be included in an amount of 10 to 50 parts by weight, preferably 20 to 40 parts by weight, based on a total of 100 parts by weight of the epoxy-based compound and the (meth)acrylate-based compound. In the above range, the curing balance between the slow-reacting epoxy and the fast acrylate can be effectively induced to achieve good adhesion between the polarizer and the liquid crystal retardation film.

The composition for the adhesive layer can be prepared by mixing the epoxy-based compound, (meth)acrylate-based compound, photocationic initiator, and photosensitizer. The composition for the adhesive layer may be a solvent-free type or may additionally contain a solvent to improve applicability (coating properties).

The composition for an adhesive layer may further include additives for imparting conductivity such as antioxidants, ultraviolet absorbers, ionic conductive agents, conductive metal oxide fine particles, additives for imparting light diffusion, viscosity modifiers, etc., to the extent that the effect of the present invention is not impaired. there is.

The polarizing plate of the present invention has excellent adhesion between the polarizer and the liquid crystal retardation film in a wide range of environments, and discoloration of the polarizer is minimized at high temperature and high humidity. The polarizing plate of the present invention includes a polarizer and a liquid crystal retardation film laminated on a lower surface of the polarizer, the polarizer and the liquid crystal retardation film are laminated by an adhesive layer, and the adhesive layer is a thioxanthone-based photosensitizer and an anthracene-based light. Contains mixtures of sensitizers. The photosensitizer contains both a thioxanthone-based photosensitizer and an anthracene-based photosensitizer, so it has excellent adhesion between the polarizer and the liquid crystal retardation film in a wide range of environments, and can minimize discoloration of the polarizer at high temperature and high humidity.

Referring to Figure 1, the polarizing plate includes a polarizer (10); An adhesive layer 20 and a liquid crystal retardation film 30 sequentially formed on one surface of the polarizer 10; And it may include a protective layer 40 laminated on the other side of the polarizer 10.

adhesive layer

The adhesive layer 20 may be formed directly on the polarizer and the liquid crystal retardation film, preferably the liquid crystal retardation layer, to adhere the polarizer and the liquid crystal retardation film, preferably the liquid crystal retardation layer.

The adhesive layer 20 may be formed of the above-described adhesive layer composition. Specifically, the adhesive layer composition may be applied to one surface of the polarizer or liquid crystal retardation film to a predetermined thickness and then photo-cured to form the adhesive layer. Light curing is curing the composition by UV irradiation and can be performed by adjusting the amount of light and wavelength depending on the application thickness of the adhesive composition.

The adhesive layer 20 may have a thickness of 0.01 ㎛ to 10 ㎛, preferably 1 ㎛ to 5 ㎛. Within the above range, adhesion between the polarizer and the liquid crystal retardation film can be secured.

liquid crystal retardation film

The liquid crystal retardation film 30 can improve screen quality by preventing reflection of external light by circularly polarizing linearly polarized light emitted after external light passes through the polarizer.

The liquid crystal retardation film 30 may include a liquid crystal retardation layer formed of a (meth)acrylic-based liquid crystal compound containing an alicyclic group or a (meth)acrylic-based liquid crystal compound containing an aromatic group. The liquid crystal retardation layer may further include additives such as a leveling agent, polymerization initiator, alignment aid, heat stabilizer, lubricant, plasticizer, and antistatic agent. The adhesive layer formed from the composition for an adhesive layer containing a mixture of a thioxanthone-based photosensitizer and an anthracene-based photosensitizer of the present invention is a liquid crystal retardation film formed from the above-described alicyclic group-containing (meth)acrylic or aromatic group-containing (meth)acrylic liquid crystal compound. The adhesion between the layer and the polarizer can be significantly increased, and discoloration from the polarizer can be prevented after being left for a long period of time at high temperature and high humidity.

The liquid crystal retardation film 30 may have a light transmittance of 5% or less at a wavelength of 380 nm, for example, 0% to 1%. Within the above range, damage to the light emitting device due to external light can be prevented.

The liquid crystal retardation film 30 may have reverse wavelength dispersion. Inverse wavelength dispersion can be easily combined with a polarizer to significantly lower reflectance from the front and sides, improving black visibility and improving screen quality. Reverse wavelength dispersion means that the short wavelength dispersion of the liquid crystal retardation film has a lower value than the long wavelength dispersion. “Short wavelength dispersibility” is Re(450)/Re(550), and “long wavelength dispersion” is Re(650)/Re(550). Re(450), Re(550), and Re(650) are the in-plane retardation of the liquid crystal retardation film at wavelengths of 450 nm, 550 nm, and 650 nm, respectively.

The liquid crystal retardation film 30 may have an in-plane retardation of 100 nm to 220 nm, specifically 100 nm to 180 nm, at a wavelength of 550 nm. Within the above range, reflectance can be lowered from the front and sides and black visibility can be improved.

The liquid crystal retardation film 30 may have a thickness of 0.1 μm to 30 μm, for example, 1 μm to 10 μm. Within the above range, the polarizer can be made thinner and the target phase difference can be achieved.

In one embodiment, the liquid crystal retardation film may be composed of a single layer of liquid crystal retardation layer.

In another embodiment, the liquid crystal retardation film may be a laminate of a first liquid crystal retardation layer and a second liquid crystal retardation layer having different in-plane retardation at a wavelength of 550 nm. The first liquid crystal retardation layer may have an in-plane retardation of 100 nm to 220 nm, specifically 100 nm to 180 nm, at a wavelength of 550 nm. At this time, the second liquid crystal retardation layer may have an in-plane retardation of 225 nm to 350 nm, specifically 225 nm to 300 nm, at a wavelength of 550 nm. At this time, the first liquid crystal retardation layer and the second liquid crystal retardation layer may be laminated in that order from the polarizer, or the second liquid crystal retardation layer and the first liquid crystal retardation layer may be laminated in that order from the polarizer.

polarizer

The polarizer 10 is formed on the liquid crystal retardation film and can polarize external or internal light. When the liquid crystal retardation film is a liquid crystal retardation layer, the liquid crystal retardation film can be directly formed on the polarizer by coating and curing the composition to form the liquid crystal retardation layer on the polarizer.

The polarizer 10 may include a polyvinyl alcohol-based polarizer in which a polyvinyl alcohol-based film is dyed with iodine or the like. For example, polyvinyl alcohol-based polarizer is manufactured by dyeing a polyvinyl alcohol film with iodine or dichroic dye and stretching it in a certain direction. Specifically, it is manufactured through a swelling process, dyeing step, and stretching step. Methods for performing each step are commonly known to those skilled in the art.

The polarizer 10 may have a thickness of 1 μm to 50 μm. It can be used in a light emitting display device within the above range.

protective layer

The protective layer 40 may be formed on the upper surface of the polarizer to support the polarizer. The protective layer may include one or more of an optically transparent, protective film, or protective coating layer.

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, an additional stretching process may be added. The resin is a cellulose ester-based resin containing triacetylcellulose, a cyclic polyolefin-based resin containing cyclic polyolefin (cyclic olefin polymer, COP), a polycarbonate-based resin, a polyethylene terephthalate (PET), etc. Polyacrylate-based resins, including ester-based resins, polyethersulfone-based resins, polysulfone-based resins, polyamide-based resins, polyimide-based resins, acyclic-polyolefin-based resins, polymethyl methacrylate resins, and polyvinyl It may include one or more of alcohol-based resin, polyvinyl chloride-based resin, and polyvinylidene chloride-based resin. Preferably, the protective film may be a film formed of a cyclic polyolefin-based resin including cyclic polyolefin.

When the protective layer is a protective coating type, good adhesion to the polarizer, transparency, mechanical strength, thermal stability, moisture barrier, and durability can be improved. In one embodiment, the protective coating layer for the protective layer may be formed of an active energy ray curable resin composition containing an active energy ray curable compound and a polymerization initiator.

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 compound having at least one (meth)acryloyloxy group in the molecule.

The thickness of the protective layer 40 may be 5㎛ to 200㎛, specifically, 30㎛ to 120㎛, 50㎛ to 100㎛ for the protective film type, and 5㎛ to 50㎛ for the protective coating type. You can. It can be used in a light emitting display device within the above range.

Although not shown in FIG. 1, a functional coating layer, for example, a hard coating layer, an anti-fingerprint layer, an anti-reflection layer, etc. may be further formed on the upper surface of the protective layer 40.

Although not shown in FIG. 1, when the protective layer 40 is a protective film type, an adhesive layer may be further formed between the protective layer and the polarizer. The adhesive layer may be formed of a common adhesive for polarizing plates, for example, a water-based adhesive, a photocurable adhesive, or a pressure-sensitive adhesive.

The optical display device of one embodiment of the present invention includes the polarizing plate of the present invention. For example, the optical display device may be a light-emitting display device including a light-emitting device, and preferably an organic light-emitting display device.

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 should not be construed as limiting the present invention in any way.

Example 1

(1) Manufacturing adhesive composition for light-curable polarizer

As an epoxy compound, 40 parts by weight of a bifunctional alicyclic epoxy compound (2021P, Daicel) and 40 parts by weight of a bifunctional aromatic glycidyl ether compound (Bisphenol A diglycidyl ether, Kukdo Chemical), ( Mix 10 parts by weight of a meth)acrylate-based compound, 4-hydroxybutyl acrylate (Osaka Organic Co., Ltd.) and 10 parts by weight of a monofunctional aromatic (meth)acrylate-based compound (phenoxyethyl acrylate, Miwon Co., Ltd.) to form a mixture. Manufactured. In the mixture, 4 parts by weight of a photocationic initiator (Irgacure 250, diaryliodonium salt, 75% solid content, IGM Resin), and a thioxanthone-based photosensitizer (DETX-S, diethyl thioxanthone, A solvent-free adhesive composition for a photocurable polarizer was prepared by adding 0.5 parts by weight of Nipponkayaku and 0.5 parts by weight of an anthracene-based photosensitizer (9,10-dibutoxyanthracene, UVS-1331, Kawasaki Kasei Chemical).

(2) Polarizer manufacturing

A polyvinyl alcohol film (PE30, Kuraray, saponification: 99.5, thickness: 30㎛) was dyed by immersing it in a 0.3% iodine aqueous solution and then MD stretched at a stretching ratio of 5. The stretched polyvinyl alcohol film was immersed in a 3% boric acid solution and a 2% potassium iodide aqueous solution for color correction, and dried at 50°C for 4 minutes to prepare a polarizer (thickness: 7㎛).

A cyclic olefin-based film (Zeon, thickness: 28㎛) was prepared as a transparent protective film, and the film was corona treated with a corona processor (AFS) at a speed of 10mpm and an output of 1000W. As another transparent protective film, a triacetylcellulose film (Konica Minolta, Normal TAC, thickness: 40㎛) was prepared without saponification treatment.

Polyvinyl alcohol-based resin Z200 containing an acetoacetyl group (average degree of polymerization: 1200, degree of saponification: 98.5 mol%, degree of acetoacetylation: 5 mol%, Mitsubishi Chemical Co., Ltd.) was dissolved in water at 95°C for 60 minutes and then completely cooled at room temperature. used. As a crosslinking agent, Zircosol-ZN (Cheil Hee Element Chemical Co., Ltd.) was added to 100 parts by weight of polyvinyl alcohol aqueous solution at a 0.1% weight ratio and mixed to prepare an adhesive composition for an aqueous polarizer.

The adhesive composition for an aqueous polarizer was applied to the upper and lower surfaces of the polarizer to a predetermined thickness, and then a corona-treated cyclic olefin-based film was applied to the upper surface of the polarizer, and a saponified film was applied to the lower surface of the polarizer. The untreated triacetylcellulose films were each laminated, then dried at 80°C for 3 minutes, and the water-based adhesive layer and the unsaponifiable triacetylcellulose film on the lower side of the polarizer were removed.

A liquid crystal retardation layer (inverse wavelength dispersion, cyclic (aromatic group)) acrylate-based liquid crystal retardation layer on the upper surface of the polyethylene terephthalate (PET) film, which is a base film, has an in-plane retardation of about 116 nm at a wavelength of 550 nm, and a light transmittance of 1 at a wavelength of 380 nm. %, DNP Co.) prepared a liquid crystal retardation film formed. The surface of the liquid crystal retardation layer was surface treated by corona irradiation using a corona treatment machine (AFS) at a speed of 10 mpm and an output of 1000 W. The solvent-free adhesive composition for a light-curable polarizer prepared above is applied to the surface of the surface-treated liquid crystal retardation layer to a thickness of about 3㎛ to form a coating film, and the lower surface of the polarizer from which the triacetylcellulose film and aqueous adhesive layer have been removed. and the above coating film were laminated. Then, UV was irradiated from the PET film side of the liquid crystal retardation film toward the cyclic olefin-based polymer film using a metal halide lamp with a light amount of about 1000 mJ/cm ² based on UVA to photocure the coating film. Then, the PET film was removed to prepare a polarizer in which the cyclic olefin polymer film-aqueous adhesive layer (thickness: 0.1㎛)-polarizer-photocurable adhesive layer (thickness: 3㎛)-liquid crystal retardation layer were sequentially stacked.

In a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer, and a stirring device, 100 parts by weight of n-butyl acrylate, 2 parts by weight of acrylic acid, 0.2 parts by weight of 2-hydroxyethyl acrylate, and 2,2'-azobis. A solution was prepared by adding 0.3 parts by weight of isobutyronitrile together with ethyl acetate. The solution was stirred under a nitrogen gas atmosphere and reacted at 60°C for 6 hours to obtain a solution containing an acrylic polymer with a weight average molecular weight of 1.7 million. Additionally, methyl ethyl ketone was added to the solution containing the acrylic polymer to obtain an acrylic polymer solution with a solid content of 20%. For 100 parts by weight of solid content of the acrylic polymer solution, 0.3 parts by weight of isocyanate crosslinking agent L-45 (Soken) was added, and 0.05 parts by weight of silane coupling agent KMB-403 (Shin-Etsu) was added to prepare a pressure-sensitive adhesive layer solution. manufactured. The pressure-sensitive adhesive solution was applied to the surface of a release sheet made of a peeled polyethylene terephthalate film (thickness 38 μm) to a thickness of 20 μm after drying, and dried to form a pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer was laminated with the liquid crystal retardation layer of the polarizing plate to prepare a polarizing plate with the pressure-sensitive adhesive layer formed thereon.

Examples 2 to 6

In preparing the solvent-free adhesive composition for a photo-curable polarizing plate of Example 1, the composition and polarizing plate were prepared in the same manner as in Example 1, except that the composition of the photo cationic initiator and the photosensitizer were changed as shown in Table 1 below. did. (In Table 1 below, '-' means that the corresponding ingredient is not included.)

Example 7

Except that 40 parts by weight of the bifunctional alicyclic epoxy compound (2021P, Daicel) was changed to 40 parts by weight (TTA800, Tetrachem), and the composition of the photocationic initiator and photosensitizer was changed as shown in Table 1 below. The composition and polarizer were prepared in the same manner as Example 1.

Example 8

40 parts by weight of a bifunctional aromatic glycidyl ether compound (bisphenol A diglycidyl ether, Kukdo Chemical Co., Ltd.) was changed to 40 parts by weight of EX-201 (resorcinol diglycidyl ether, Nagase Chemtex Co., Ltd.), and A composition and a polarizing plate were prepared in the same manner as in Example 1, except that the compositions of the cationic initiator and photosensitizer were changed as shown in Table 1 below.

Example 9

Change 40 parts by weight of the bifunctional alicyclic epoxy compound to 40 parts by weight of TTA800, and change 40 parts by weight of the bifunctional aromatic glycidyl ether compound to 40 parts by weight of EX-201 (resorcinol diglycidyl ether, Nagase Chemtex). A composition and a polarizing plate were prepared in the same manner as in Example 1, except that the compositions of the photo cationic initiator and the photosensitizer were changed as shown in Table 1 below.

Comparative Examples 1 to 5

In preparing the solvent-free adhesive composition for a photo-curable polarizing plate of Example 1, the composition and polarizing plate were prepared in the same manner as in Example 1, except that the composition of the photo cationic initiator and the photosensitizer were changed as shown in Table 1 below. did.

The physical properties in Table 1 below were evaluated for the polarizing plates manufactured in Examples and Comparative Examples, and the results are shown in Table 1 below.

(1) Adhesion at room temperature (initial adhesion): The polarizing plate with the adhesive layer prepared in the examples and comparative examples was cut into a rectangular shape of polarizer MD x TD (200 mm x 25 mm). Then, the polarizing plate was laminated to an alkali-free glass plate (thickness: 0.5t) through the adhesive layer and left at room temperature for more than 30 minutes to prepare a specimen. Then, when the polarizer is peeled from the alkali-free glass plate, the polarizer is peeled from the alkali-free glass plate without separation of the polarizer and the liquid crystal retardation layer, and the alkali-free glass plate with the separated polarizer and liquid crystal retardation layer attached is mounted at a 90° angle in the Texture Analyzer. Then, measure the peeling force (gf/25mm) between the polarizer and the liquid crystal retardation layer at a speed of 300mm per minute at 25°C. If the peeling force is 100gf/25mm or more, OK, the polarizer and the liquid crystal retardation layer are separated from each other and only the polarizer is peeled off. After mounting the alkali-free glass plate with the separated polarizer and liquid crystal retardation layer attached to the Texture Analyzer at a 90° angle, peeling is performed by measuring the peeling force (gf/25mm) between the polarizer and liquid crystal retardation layer measured at a speed of 300 mm per minute at 25°C. If the force was less than 100gf/25mm, it was considered NG.

(2) Adhesion after high temperature and high humidity: The specimen was manufactured in the same manner as (1). Then, the specimen was left in the chamber at 60°C and 95% relative humidity for 3 days, and then the specimen was taken out and left at room temperature for 30 minutes. Then, when the polarizer is peeled from the alkali-free glass plate, the polarizer is peeled from the alkali-free glass plate without separation of the polarizer and the liquid crystal retardation layer, and the alkali-free glass plate with the separated polarizer and liquid crystal retardation layer attached is mounted at a 90° angle in the Texture Analyzer. Then, measure the peeling force (gf/25mm) between the polarizer and the liquid crystal retardation layer at a speed of 300mm per minute at 25°C. If the peeling force is 100gf/25mm or more, OK, the polarizer and the liquid crystal retardation layer are separated from each other and only the polarizer is peeled off. After mounting the alkali-free glass plate with the separated polarizer and liquid crystal retardation layer attached to the Texture Analyzer at a 90° angle, peeling is performed by measuring the peeling force (gf/25mm) between the polarizer and liquid crystal retardation layer measured at a speed of 300 mm per minute at 25°C. If the force was less than 100gf/25mm, it was considered NG.

(3) Color loss of iodine: The polarizing plate prepared in the examples and comparative examples was cut into a 50 mm x 50 mm square with the absorption axis direction of the polarizer at an angle of 45° and attached to a glass plate to prepare a specimen. It was placed in a chamber at 60°C and 95% relative humidity, left for 500 hours, and then taken out. Thereafter, as shown in FIG. 2, the length (5) where the iodine color loss occurred in the specimen (1) is measured diagonally from the four corners of the specimen, and the level is classified as follows.

○: Less than 1mm

△: 1~3mm

×: greater than 3 mm

Photocationic initiator photosensitizer Adhesion at room temperature Adhesion after high temperature and humidity Color loss of iodine A B C D E weight ratio Example 1 4 - 0.5 0.5 - 1:1 OK OK ○ Example 2 4 - One 0.5 - 1:0.5 OK OK ○ Example 3 4 - 1.5 0.5 - 1:0.33 OK OK ○ Example 4 4 - 0.5 One - 1:2 OK OK ○ Example 5 4 - 0.5 1.5 - 1:3 OK OK △ Example 6 - 6 0.5 0.5 - 1:1 OK OK △ Example 7 4 - One 0.5 - 1:0.5 OK OK ○ Example 8 4 - One 0.5 - 1:0.5 OK OK ○ Example 9 4 - One 0.5 - 1:0.5 OK OK ○ Comparative Example 1 4 - 0.5 - - - OK NG △ Comparative example 2 4 - - 0.5 - - OK NG ⅹ Comparative Example 3 - 6 0.5 - - - NG NG ⅹ Comparative Example 4 - 6 - 0.5 - - OK NG ⅹ Comparative Example 5 4 - 0.5 - 0.5 - OK NG △

A: Photocationic initiator (Irgacure 250, Diaryliodonium Salt, 75% solid content, IGM Resins)

B: Photocationic initiator (CPI-100P, Triarylsulfonium Salt, 50% solid content, San Apro)

C: Light sensitizer: DETX-S, Diethyl Thioxthantone, Nipponkayaku Co., Ltd.

D: Light sensitizer: UVS-1331, 9,10-dibutoxy Anthrachene, Kawasaki Kasei Chemical

E: Light sensitizer: TR-PSS-202, 3 Benzoyl 7 diethylaminocoumarin, Tronly company

Weight ratio: Composition thioxanthone-based photosensitizer: solid content weight ratio of anthracene-based photosensitizer

As shown in Table 1, the adhesive composition for a polarizer of the present invention implements an adhesive layer with excellent adhesion between the polarizer and the liquid crystal retardation film in a wide range of environments and prevents discoloration from the polarizer after being left for a long period of time at high temperature and high humidity. .

On the other hand, the polarizing plate adhesive composition of the comparative example that did not satisfy the composition of the present invention failed to implement an adhesive layer that satisfied all the effects of the present invention.

Simple modifications or changes to the present invention can be easily implemented 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 (18)

Contains epoxy-based compounds, (meth)acrylate-based compounds, photocationic initiators and photosensitizers,
An adhesive composition for a polarizing plate, wherein the photosensitizer includes a mixture of a thioxanthone-based photosensitizer and an anthracene-based photosensitizer.
The adhesive composition for a polarizing plate according to claim 1, wherein the weight ratio of the thioxanthone-based photosensitizer to the anthracene-based photosensitizer is 1:0.1 to 1:10.
The adhesive composition for a polarizing plate according to claim 1, wherein the mixture is comprised in an amount of 90% to 100% by weight of the photosensitizer.
The adhesive composition for a polarizing plate according to claim 1, wherein the anthracene-based photosensitizer includes an alkoxy group-containing anthracene-based photosensitizer.
The adhesive composition for a polarizing plate according to claim 1, wherein the thioxanthone-based photosensitizer includes an alkyl group- or halogen-containing thioxanthone-based photosensitizer.
The adhesive composition for a polarizing plate according to claim 1, wherein the photo cationic initiator includes an onium salt having diaryliodonium or triarylsulfonium.
The adhesive composition for a polarizing plate according to claim 1, wherein the epoxy compound includes a mixture of a bifunctional alicyclic epoxy compound and an aromatic group-containing bifunctional glycidyl ether compound.
The adhesive composition for a polarizing plate according to claim 7, wherein the aromatic group-containing bifunctional glycidyl ether compound is contained in an amount of 70 to 150 parts by weight based on 100 parts by weight of the bifunctional alicyclic epoxy compound.
The adhesive for a polarizing plate according to claim 7, wherein the mixture of the bifunctional alicyclic epoxy compound and the aromatic group-containing bifunctional glycidyl ether compound is comprised in 90% by weight to 100% by weight of the epoxy compound. Composition.
The adhesive composition for a polarizing plate according to claim 1, wherein the (meth)acrylate-based compound includes a mixture of one or more hydroxyl group-containing (meth)acrylate and aromatic group-containing (meth)acrylate.
The method of claim 1, wherein the composition
60 to 80 parts by weight of the epoxy compound, 20 to 40 parts by weight of the (meth)acrylate compound, based on a total of 100 parts by weight of the epoxy compound and the (meth)acrylate compound,
A polarizing plate comprising 0.5 parts by weight to 10 parts by weight of the photo cationic initiator and 0.5 parts by weight to 10 parts by weight of the photosensitizer, based on a total of 100 parts by weight of the epoxy compound and the (meth)acrylate compound. Adhesive composition for use.
Comprising a polarizer and a liquid crystal retardation film laminated on a lower surface of the polarizer,
The polarizer and the liquid crystal retardation film are laminated by an adhesive layer,
The adhesive layer is a polarizing plate comprising a mixture of a thioxanthone-based photosensitizer and an anthracene-based photosensitizer.
The polarizing plate of claim 12, wherein the liquid crystal retardation film has a light transmittance of 5% or less at a wavelength of 380 nm.
The polarizing plate of claim 12, wherein the liquid crystal retardation film includes a liquid crystal retardation layer formed of an alicyclic group-containing (meth)acrylic-based liquid crystal compound or an aromatic group-containing (meth)acrylic-based liquid crystal compound.
The polarizing plate of claim 12, wherein the liquid crystal retardation film has reverse wavelength dispersion.
The method of claim 12, wherein the thioxanthone-based photosensitizer includes an alkyl group- or halogen-containing thioxanthone-based photosensitizer, and the anthracene-based photosensitizer includes an alkoxy group-containing anthracene-based photosensitizer. , polarizer.
The polarizing plate of claim 12, wherein the adhesive layer is formed of the adhesive composition for polarizing plates of any one of claims 1 to 11.
An optical display device comprising the polarizer of claim 12.