WO2022108205A1 - Polarizing plate and optical display device comprising same - Google Patents

Abstract

Provided are a polarizing plate and an optical display device comprising same, the polarizing plate comprising: a polarizer; a protective coating layer formed on the top surface of the polarizer; and a protective layer and an adhesive layer formed sequentially from the polarizer on the bottom surface of the polarizer, wherein the protective coating layer is formed from a thermosetting composition, and the modulus of the polarizing plate measured by a microindenter on the protective coating layer-side is approximately 10MPa or higher.

Description

Polarizing plate and optical display including same

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

An optical display device is provided with a polarizing plate for the purpose of improving light efficiency, improving screen quality, and the like. The polarizing plate includes a polarizer and a protective film formed on at least one surface of the polarizer. The polarizing plate may be laminated on an adherend after coating a pressure-sensitive adhesive composition on one surface of the protective film or laminating an adhesive film formed of the pressure-sensitive adhesive composition.

Recently, as the thinning trend of optical display devices continues, the polarizing plate also tends to be thinned. Various methods may be considered as a method of thinning the polarizing plate, but recently, a method of using a protective coating layer as a protective layer of a polarizer instead of a protective film is being considered. On the other hand, the polarizing plate, particularly the viewer-side polarizing plate, may be easily exposed to external ultraviolet light, and the ultraviolet rays entering the polarizing plate may damage an adherend of the polarizing plate, for example, a liquid crystal panel or an OLED panel. Therefore, it should be possible to obtain a thinning effect and a UV blocking effect at the same time.

The protective coating layer may provide a thinning effect of the polarizing plate. However, the polarizing plate may be warped due to a difference in thickness and a difference in physical properties of the protective layers stacked on the upper and lower surfaces of the polarizer, respectively. In addition, since the protective coating layer is directly formed on the polarizer, it should be able to prevent cracks in the polarizer under reliability conditions such as thermal shock.

Background art of the present invention is disclosed in Japanese Patent Application Laid-Open No. 2013-072951 and the like.

An object of the present invention is to provide a polarizing plate having a thinning effect.

Another object of the present invention is to provide a polarizing plate that can contain a relatively excessive amount of UV absorber in the protective coating layer, thereby minimizing damage to a polarizer and an adherend of the polarizing plate, for example, UV damage to a display panel.

Another object of the present invention is to provide a polarizing plate that provides a barrier effect to the polarizer and suppresses the bending of the polarizer.

One aspect of the present invention is a polarizing plate.

1. The polarizer is a polarizer; a protective coating layer formed on the upper surface of the polarizer; a protective layer and an adhesive layer sequentially formed from the polarizer on a lower surface of the polarizer; the protective coating layer is formed of a thermosetting composition; More than that.

In 2.1, the protective coating layer may be directly formed on the upper surface of the polarizer.

In 3.1-2, only the protective coating layer as a protective layer of the polarizer may be stacked on the upper surface of the polarizer.

In 4.1-3, the thermosetting composition may include an adhesive resin, an isocyanate-based curing agent, and a UV absorber.

In 5.4, the UV absorber may be included in an amount of about 0.1 parts by weight to about 10 parts by weight based on 100 parts by weight of the adhesive resin.

In 6.4, the UV absorber may have a maximum absorption wavelength of 390 nm or more.

In 7.4, the UV absorber may include at least one of indole-based and triazine-based.

In 8.1-7, the adhesive resin is a monomer mixture comprising a (meth)acrylic monomer having an alkyl group and a (meth)acrylic monomer having a hydroxyl group, and at least one or more of the monomers included in the monomer mixture is free of a homopolymer It may include a (meth)acrylic copolymer of a monomer mixture including a monomer having a transition temperature of about 50° C. or higher.

In 9.8, the monomer having a glass transition temperature of about 50° C. or higher of the homopolymer may be included in an amount of about 1 wt% to about 60 wt% of the monomer mixture.

In 10.8-9, the monomer having a glass transition temperature of about 50° C. or higher of the homopolymer is methyl methacrylate, t-butyl methacrylate, iso-propyl methacrylate, sec-butyl methacrylate, isobornyl methacrylic one or more of the rates.

In 11.8-10, the monomer mixture may include about 85 wt% to about 99.9 wt% of the (meth)acrylic monomer having the alkyl group, and about 0.1 wt% to about 15 wt% of the (meth)acrylic monomer having the hydroxyl group have.

In 12.8-11, the monomer mixture may further include a monomer having a carboxylic acid group.

In 13.8-12, the monomer mixture is about 70 wt% to about 98 wt% of the (meth)acrylic monomer having an alkyl group, about 0.1 wt% to about 15 wt% of the (meth)acrylic monomer having a hydroxyl group, and the carboxylic acid group It may include from about 0.1 wt% to about 15 wt% of a monomer having

In 14.1-13, the isocyanate-based curing agent may include a polyisocyanate-based curing agent including a urethane bond and a plurality of units containing an alkylene group having two or more carbon atoms.

In 15.1-14, the isocyanate-based curing agent may include a polyisocyanate curing agent having a plurality of units having the following formula (1):

[Formula 1]

*-R ¹ -O-(C=O)NH-R ² -NCO

(In Formula 1, * is a connection site,

R ¹ and R ² are the same or different and are a divalent aliphatic hydrocarbon group having 2 to 20 carbon atoms).

In 16.1-15, 100 parts by weight of the adhesive resin, about 10 parts by weight to about 40 parts by weight of the isocyanate-based curing agent, and about 0.1 parts by weight to about 10 parts by weight of the UV absorber may be included.

In 17.1-16, the polarizing plate may have a light transmittance of about 3% or less at a wavelength of 380 nm or 405 nm, respectively.

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

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

In 19.18, the optical display device may include the polarizing plate, a transparent adhesive film laminated on an upper surface of the polarizing plate, and an OLED panel formed on a lower surface of the polarizing plate.

In 20.19, a cover glass may be further laminated on the upper surface of the transparent adhesive film.

The present invention provides a polarizing plate having a thinning effect.

The present invention provides a polarizing plate that can contain a relatively excessive amount of UV absorber in the protective coating layer, thereby minimizing damage to a polarizer and an adherend of the polarizing plate, for example, UV damage to a display panel.

The present invention provides a polarizing plate that provides a barrier effect to the polarizer and suppresses the bending of the polarizer.

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

Hereinafter, embodiments of the present application will be described in more detail with reference to the accompanying drawings. However, the technology disclosed in the present application is not limited to the embodiments described herein and may be embodied in other forms. However, the embodiments introduced herein are provided so that the disclosed content may be thorough and complete, and the spirit of the present application may be sufficiently conveyed to those skilled in the art.

In order to clearly express the components of each device in the drawings, the sizes such as widths and thicknesses of the components are somewhat enlarged, and the sizes of the widths and thicknesses of the components are limited to the scope of the present invention. it's not going to be In a plurality of drawings, the same reference numerals refer to substantially the same components.

In this specification, "upper" and "lower" are defined based on the drawings, and depending on the perspective of the city, "upper" may be changed to "lower" and "lower" to "upper", and "on" or What is referred to as “on” may include cases where other structures are interposed in the middle as well as immediately above. On the other hand, reference to "directly on" or "immediately on" or "directly forming" refers to no intervening other structures such as intermediates.

As used herein, "modulus" measured in terms of a protective coating layer with respect to a polarizing plate means an elastic modulus.

As used herein, “(meth)acryl” means acrylic and/or methacrylic.

In the present specification, "weight average molecular weight" may be a value obtained by polystyrene conversion in gel permeation chromatography.

In the present specification, "substituted" in "substituted or unsubstituted" means an ester group in which at least one hydrogen atom of the functional group has an alkyl group having 1 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, and 2 carbon atoms. It means substituted with an alkynyl group of 10 to 10, a hydroxyl group, or the like.

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

The polarizing plate of the present invention provided a thinning effect of the polarizing plate by forming a protective coating layer instead of a protective layer on one surface of the polarizer. The polarizing plate of the present invention may contain a relatively excessive amount of UV absorber compared to the photocurable composition by forming the protective coating layer with a thermosetting composition and forming a protective coating layer on the outermost side where external light is incident on the polarizer. It is possible to minimize damage to the adherend, for example, by UV of the display panel. The polarizing plate of the present invention provided a barrier effect to the polarizer and at the same time suppressing the curvature of the polarizing plate by having a modulus measured by a micro-indenter on the protective coating layer of about 10 MPa or more.

The polarizing plate of the present invention is a polarizer; a protective coating layer formed on the upper surface of the polarizer; a protective layer and an adhesive layer sequentially formed from the polarizer on a lower surface of the polarizer; the protective coating layer is formed of a thermosetting composition; to be.

Hereinafter, a polarizing plate according to an embodiment of the present invention will be described with reference to FIG. 1 .

Referring to FIG. 1 , the polarizing plate includes a polarizer 100 , a protective coating layer 200 formed on the upper surface of the polarizer 100 , a protective layer 300 and an adhesive layer 400 formed on the lower surface of the polarizer 100 . do.

The polarizing plate has a modulus of about 10 MPa or more measured with a micro-indenter in terms of the protective coating layer. In the above range, it is possible to suppress the occurrence of cracks in the polarizer due to thermal shock by providing a barrier effect to the polarizer, and to suppress warpage. The present invention suppresses cracks in the polarizer due to thermal shock by forming the protective coating layer directly on the polarizer and controlling the modulus measured with a micro indenter to about 10 MPa or more on the surface of the protective coating layer, and dichroism containing iodine in the polarizer It was possible to reduce the possibility of discoloration of the dye and to suppress the bending of the polarizer caused by the difference in thickness between the protective coating layer formed on the upper surface of the polarizer and the protective layer and the adhesive layer formed on the lower surface of the polarizer.

Specifically, the modulus is, for example, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40 MPa, from about 10 MPa to about 40 MPa, more specifically from about 10 MPa to about 30 MPa.

protective coating layer

The protective coating layer 200 may be positioned on a portion of the polarizing plate to which external light is initially incident. That is, only the protective coating layer 200 as a protective layer may be stacked on the upper surface of the polarizer 100 . Therefore, as will be described in detail below, the protective coating layer can block UV damage to the adherend of the polarizer and the polarizing plate by effectively blocking UV of external light by containing a UV absorber.

The protective coating layer 200 may be directly formed on the upper surface of the polarizer 100 . The "directly formed" means that any adhesive layer or adhesive layer is not interposed between the protective coating layer and the polarizer.

The protective coating layer 200 may have a thickness of about 15 μm or less, specifically greater than about 0 μm and about 15 μm or less. In the above range, it is possible to obtain a thinning effect of the polarizing plate.

The protective coating layer 200 is optically transparent, so that the total light transmittance in a visible light region, for example, a wavelength of 550 nm, may be about 90% or more, specifically, about 90% to about 100%. In the above range, it can be used for the polarizing plate without affecting the light emitted from the polarizing plate.

The protective coating layer 200 may be formed of a thermosetting composition including an adhesive resin, an isocyanate-based curing agent, and a UV absorber. Since the protective coating layer is formed of the thermosetting composition, the protective coating layer may include a relatively excessive amount of UV absorber, thereby minimizing damage to the polarizer and the adherend of the polarizing plate, for example, UV damage to the display panel.

The adhesive resin may increase the modulus measured by the micro-indenter in terms of the protective coating layer with respect to the polarizing plate, and may improve adhesion to the polarizer.

The adhesive resin is a monomer mixture including a (meth)acrylic monomer having an alkyl group and a (meth)acrylic monomer having a hydroxyl group, and at least one of the monomers included in the monomer mixture has a glass transition temperature of 50° C. or higher. It may be a more preferable (meth)acrylic copolymer to include a monomer.

At least one of the monomers included in the monomer mixture contains a monomer having a glass transition temperature of about 50° C. or higher of the homopolymer, so that the modulus of the present invention measured by a micro indenter in terms of the protective coating layer with respect to the polarizing plate will be reached. can Specifically, the monomer mixture has a glass transition temperature of, for example, about 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125 of the homopolymer. , 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, 200 °C, about 50 °C to about 200 °C, more specifically about 80 °C to about 150 °C It may contain a phosphorus monomer.

The monomer having a glass transition temperature of about 50° C. or higher of the homopolymer is about 1% to about 60% by weight of the monomer mixture, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 , 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35 , 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60 % by weight, specifically from about 10% to about 60% by weight, from about 20% to about 60% by weight, from about 30% to about 60% by weight, more specifically from about 40% to about 50% by weight have. In the above range, it can help to reach the modulus measured by the micro-indenter in terms of the protective coating layer for the polarizer.

The (meth)acrylic monomer having an alkyl group may include at least one of (meth)acrylic acid esters having an alkyl group having 1 to 20 carbon atoms that is substituted or unsubstituted. For example, the (meth)acrylic monomer having an alkyl group is methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, iso-propyl (meth)acrylate, n-butyl (meth)acrylate ) acrylate, t-butyl (meth) acrylate, iso-butyl (meth) acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl ( Meth) acrylate, heptyl (meth) acrylate, n-octyl (meth) acrylate, iso-octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylic and one or more of isobornyl (meth)acrylate, but is not limited thereto.

Among the (meth)acrylic monomers having an alkyl group, monomers having a glass transition temperature of about 50° C. or higher of the homopolymer may be selected by referring to product catalogs and the like. For example, among the (meth)acrylic monomers having an alkyl group, the monomer having a glass transition temperature of about 50° C. or higher of the homopolymer is methyl methacrylate, t-butyl methacrylate, iso-propyl methacrylate, sec-butyl methacrylic rate, isobornyl methacrylate, and may include, but is not limited to, one or more of.

The (meth)acrylic monomer having a hydroxyl group is a (meth)acrylic monomer having a hydroxyl group and a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a (meth)acrylic monomer having a hydroxyl group and a substituted or unsubstituted alicyclic group having 3 to 20 carbon atoms (meth) ) may include one or more of an acrylic monomer, a (meth)acrylic monomer having a hydroxyl group and a substituted or unsubstituted aromatic group having 6 to 20 carbon atoms. For example, the (meth)acrylic monomer having a hydroxyl group is 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxy Butyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 1,4-cyclohexanedimethanol mono (meth) acrylate, 1-chloro-2-hydroxypropyl (meth) acrylate, diethylene One of glycol mono (meth) acrylate, 2-hydroxy-3-phenyloxypropyl (meth) acrylate, 4-hydroxycyclopentyl (meth) acrylate, and 4-hydroxycyclohexyl (meth) acrylate may include more than one.

For example, among monomers having a hydroxyl group, the homopolymer may include one or more monomers having a glass transition temperature of about 20° C. or higher, but is not limited thereto. For example, the monomer having a hydroxyl group has a glass transition temperature of about 20° C. or higher of the homopolymer, for example, about 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, It may include at least one monomer having a temperature of 80°C, specifically, about 20°C to about 80°C. Among monomers having a hydroxyl group, the homopolymer having a glass transition temperature of about 20° C. or higher may include, but is not limited to, 2-hydroxyethyl methacrylate.

The monomer mixture may further include a monomer having a carboxylic acid group. The monomer having a carboxylic acid group may include, but is not limited to, (meth)acrylic acid, fumaric acid, itaconic acid, and the like.

In one embodiment, the monomer mixture is about 85% to about 99.9% by weight of a (meth)acrylic monomer having an alkyl group, for example, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 99.9 wt%, specifically about 90 wt% to about 95 wt%, about 0.1 wt% to about 15 wt% of a (meth)acrylic monomer having a hydroxyl group, for example 0.1, 0.5 , 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15% by weight, specifically about 1% to about 10% by weight may be included. In the above range, it is possible to control the modulus of the barrier properties and the degree of curing.

In another embodiment, the monomer mixture is about 70% to about 98% by weight of a (meth)acrylic monomer having an alkyl group, for example, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79 , 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98 wt%, specifically about 85 wt% to about 90 wt% wt%, about 0.1 wt% to about 15 wt% of a (meth)acrylic monomer having a hydroxyl group For example, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 , 13, 14, 15% by weight, specifically about 1% to about 10% by weight, about 0.1% to about 15% by weight of a monomer having a carboxylic acid group For example 0.1, 0.5, 1, 2, 3, 4, 5 , 6, 7, 8, 9, 10, 11, 12, 13, 14, 15% by weight, specifically about 1% to about 10% by weight may be included. It may be possible to improve the modulus properties by providing additional curing properties in the above range.

The monomer mixture includes (meth)acrylamide, acrylonitrile, benzyl methacrylate, cyclohexyl methacrylate, N,N-dimethylacrylamide, styrene, and dihydro It may further include one or more of dicyclopentadienyl acrylate (Dihydrodicyclopentadienyl Acrylate, DCPA), but is not limited thereto.

The (meth)acrylic copolymer may be prepared by polymerizing the monomer mixture by a conventional polymerization method. Polymerization methods may include conventional methods known to those skilled in the art. For example, the (meth)acrylic copolymer may be prepared by adding an initiator to the monomer mixture, and then performing general copolymer polymerization, for example, suspension polymerization, emulsion polymerization, solution polymerization, and the like. The polymerization temperature may be 60° C. to 70° C., and the polymerization time may be 6 hours to 8 hours. As the initiator, a conventional one including an azo polymerization initiator and/or a peroxide such as benzoyl peroxide or acetyl peroxide may be used.

Adhesive resin Specifically, the (meth)acrylic copolymer has a weight average molecular weight of about 200,000 or more, for example, 200,000, 250,000, 300,000, 350,000, 400,000, 450,000, 500,000, 550,000, 600,000 , 650,000, 700,000, 750,000, 800,000, 850,000, 900,000, 950,000, 1 million, specifically 200,000 to 1,000,000, more specifically 100,000 to 300,000. In the above range, it may be easy to reach the effect of the present invention.

The isocyanate-based curing agent may cure the adhesive resin to improve the degree of crosslinking of the protective coating layer and increase adhesion to the polarizer. The isocyanate-based curing agent may be a thermal curing agent to thermally cure the adhesive resin to form a protective coating layer. As described above, since the protective coating layer of the present invention is formed of a thermosetting composition, it is possible to implement a protective coating layer without problems in the degree of crosslinking of the protective coating layer even if it contains an excessive amount of the UV absorber described below.

The isocyanate-based curing agent is about 10 parts by weight to about 40 parts by weight based on 100 parts by weight of the adhesive resin, for example, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22 , 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40 parts by weight, specifically about 15 parts by weight to about 30 parts by weight may be included. Within the above range, the degree of crosslinking and adhesion of the protective coating layer may be improved, and flexibility may be improved.

The isocyanate-based curing agent may include a polyisocyanate-based curing agent including a urethane bond and a plurality of units containing an alkylene group having 2 or more carbon atoms. The polyisocyanate-based curing agent may help to reach the modulus by curing the adhesive resin. The "alkylene group" is a linear alkylene group having 6 to 20 carbon atoms, and may mean, for example, a hexamethylene group, a dodecamethylene group, or a trimethylhexamethylene group, but is not limited thereto.

In one embodiment, the isocyanate-based curing agent may include an adduct of a polyisocyanate curing agent having a plurality of urethane-modified linear alkylene group-containing units having two or more carbon atoms. For example, the polyisocyanate-based curing agent may be an aliphatic polyisocyanate containing urethane. In this case, the aliphatic polyisocyanate curing agent is a C4 to C20 diisocyanate, and includes trimethylhexamethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and the like. isocyanate, and the like. A urethane-modified polyisocyanate-based curing agent can be used as a commercially available product.

In one embodiment, the isocyanate-based curing agent may include a polyisocyanate curing agent having a unit represented by Formula 1 below. The curing agent preferably has a plurality of structural units represented by the following formula (1):

[Formula 1]

*-R ¹ -O-(C=O)NH-R ² -NCO

(In Formula 1, * is a connection site,

R ¹ and R ² are the same or different and are a divalent aliphatic hydrocarbon group having 2 to 20 carbon atoms). The aliphatic hydrocarbon group may be a linear alkylene group.

The curing agent may be synthesized by a method known to those skilled in the art or used as a commercially available product, for example, AE 700-100 (Asahi Kasehi).

The UV absorber is included in the protective coating layer to lower the content of ultraviolet rays incident on the polarizing plate among external light, thereby blocking UV damage to the polarizer and the adherend of the polarizing plate (eg, a display panel).

The UV absorber may have a maximum absorption wavelength of about 390 nm or more, specifically about 390 nm or more and about 400 nm or less, and more specifically about 390 nm or more and less than about 400 nm. In the above range, it is possible to prevent damage to the polarizer and the adherend of the polarizing plate by sufficiently absorbing light at a wavelength of 420 nm or less, a wavelength of 400 nm to 420 nm, and a wavelength of 405 nm or less of external light to lower the UV transmittance.

The 'maximum absorption wavelength' refers to a wavelength showing a maximum absorption peak, that is, a wavelength having maximum absorbance in an absorbance curve according to wavelength. The 'absorbance' may be measured by a conventional method known to those skilled in the art.

Through this, the polarizing plate has a light transmittance of about 3% or less at a wavelength of 380 nm, specifically about 0% to about 3%, or a light transmittance of about 3% or less at a wavelength of 405 nm, specifically about 0% to about 3%. have. In particular, the polarizing plate of the present invention can block even UV damage of the polarizer by making the light transmittance at a wavelength of 380 nm or less about 3%.

In one embodiment, the UV absorber may include an absorbent that has a melting point of about 100° C. or higher, specifically about 140° C. to about 220° C., and is in a solid phase at room temperature.

The UV absorber may include at least one of an indole-based absorbent and a triazine-based absorbent having the maximum absorption wavelength. In one embodiment, the indole-based absorbent may include a compound of Formula 2 below:

[Formula 2]

(In Formula 2, R ¹ is hydrogen or a substituted or unsubstituted C1 to C10 alkyl group,

R ² is hydrogen or a substituted or unsubstituted C6 to C20 aryl group,

R ³ is hydrogen or a substituted or unsubstituted C1 to C10 alkyl group,

R ⁴ is hydrogen, a cyano group (CN) or a substituted or unsubstituted C1 to C10 alkyl group,

R ⁵ is a cyano group or -(C=O)OR ⁶ (in this case, R ⁶ is a substituted or unsubstituted C1 to C10 alkyl group or a substituted or unsubstituted C6 to C20 aryl group).

Specifically, R ¹ is a C1 to C5 alkyl group, specifically a methyl group, R ² is a C6 to C10 aryl group, specifically a phenyl group, R ³ is hydrogen or a C1 to C5 alkyl group, specifically hydrogen, R ⁴ is a cyano group , R ⁵ is a cyano group or -(C=O)-OR ⁶ (in this case, R ⁶ is a substituted or unsubstituted C1 to C5 alkyl group). More specifically, the compound of Formula 2 may include a compound of Formula 2-1 or 2-2 below:

[Formula 2-1]

[Formula 2-2]

In one embodiment, the triazine-based absorbent may include a compound of Formula 3 below:

[Formula 3]

(In Formula 3,

R ¹ , R ² , and R ³ are each independently a substituted or unsubstituted hydroxyphenyl group).

The UV absorber is from about 0.1 parts by weight to about 10 parts by weight based on 100 parts by weight of the adhesive resin, for example, 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10 parts by weight, specifically about 1 part by weight to about 5 parts by weight may be included. In the above range, there may be no problems such as UV blocking effect, elution of the UV absorber from the protective coating layer.

The composition may further include a conventional thermosetting agent known to those skilled in the art in addition to the isocyanate-based curing agent.

For example, the thermosetting agent may further include one or more of a carbodiimide-based curing agent, a metal chelate-based curing agent, an aziridine-based curing agent, and an epoxy-based curing agent. The curing agent may be included in an amount of about 0.001 parts by weight to about 5 parts by weight, for example, about 0.01 parts by weight to about 1 part by weight based on 100 parts by weight of the adhesive resin. Within the above range, it may help to form a protective coating layer.

The composition may further include a silane coupling agent.

The silane coupling agent may increase the adhesion of the protective coating layer to the polarizer. The silane coupling agent may include a conventional silane coupling agent known to those skilled in the art. For example, the silane coupling agent may include, but is not limited to, an epoxy group-containing silane coupling agent such as glycidoxypropyltrimethoxysilane and glycidoxypropylmethyldimethoxysilane.

The silane coupling agent may be included in an amount of about 0.01 parts by weight to about 5 parts by weight, for example, about 0.1 parts by weight to about 2.5 parts by weight based on 100 parts by weight of the adhesive resin. In the above range, the adhesion to the polarizer may be higher.

The composition may further include a crosslinking catalyst. The crosslinking catalyst may increase the degree of crosslinking of the protective coating layer prepared from the composition. The crosslinking catalyst may include one or more of a metal or a metal containing compound. Specifically, the crosslinking catalyst may include at least one of a tin-containing compound, a zinc-containing compound, a titanium compound, and a bismuth compound. More specifically, the crosslinking catalyst may include at least one of dibutyltindilaurate and tin dimaleate.

The crosslinking catalyst may be included in an amount of 0.01 parts by weight to 1.5 parts by weight based on 100 parts by weight of the adhesive resin. In the above range, the degree of crosslinking may be increased and moisture penetration may be suppressed.

The composition may further include an additive. Additives may provide additional functionality to the protective coating layer. Specifically, the additive may include, but is not limited to, at least one of a reaction inhibitor, an adhesion enhancer, a thixotropic agent, a conductivity imparting agent, a color adjuster, a stabilizer, an antioxidant, and a leveling agent.

The composition may further increase the usual solvent in order to increase the coatability. For example, the solvent may include a ketone-based solvent such as methyl ethyl ketone and isobutyl ketone, but is not limited thereto.

The protective coating layer 200 may be formed by coating the composition on a polarizer or a release film to a predetermined thickness and then thermally curing the composition at 90° C. to 100° C. for 1 minute to 3 minutes.

polarizer

The polarizer 100 may include a polarizer made of a polyvinyl alcohol-based resin film. Specifically, the polarizer may be a polyvinyl alcohol-based polarizer in which at least one of iodine and a dichroic dye is adsorbed to a polyvinyl alcohol-based resin film, or a polyene-based polarizer manufactured by dehydrating a polyvinyl alcohol-based resin film.

The polarizer 100 may have a thickness of about 5 μm to about 30 μm, specifically, about 5 μm to about 20 μm. In the above range, it may be used for a polarizing plate, and a thinning effect of the polarizing plate may be implemented.

protective layer

The protective layer 300 may be formed on the lower surface of the polarizer 100 to protect the polarizer. The protective layer may include an optically transparent polymer film or a liquid crystal layer.

In one embodiment, the protective layer 300 is an optically transparent resin film, including a cellulose ester-based resin including triacetyl cellulose (TAC), an amorphous cyclic polyolefin (cyclic olefin polymer, COP), and the like. Polyolefin-based resin, (meth)acrylic-based resin, poly(meth)acrylate-based resin, polycarbonate (PC)-based resin, polyester-based resin including polyethylene terephthalate (PET), polyethersulfone-based resin, polysulfone Containing at least one of a phone-based resin, polyamide-based resin, polyimide-based resin, acyclic polyolefin-based resin, polyarylate-based resin, polyvinyl alcohol-based resin, polyvinyl chloride-based resin, polyvinylidene chloride-based resin, and acrylic resin can do.

The protective layer 300 may have a retardation within a predetermined range in consideration of the function of the polarizing plate. For example, the protective layer 300 may have an in-plane retardation (Re) of about 100 nm to about 350 nm at a wavelength of 550 nm. The protective layer 300 may be a laminate of two or more protective layers having the above-described in-plane retardation. In the present specification, the 'in-plane retardation (Re)' is Re = (nx - ny) x d (nx, ny is the refractive index in the slow axis direction and the fast axis direction of the passivation layer, respectively, and d is the passivation layer can be calculated as the thickness (unit: nm)).

The protective layer 300 may have a smaller or larger thickness than the protective coating layer. Specifically, the protective layer may have a thickness of about 0.1 μm to about 200 μm, specifically about 10 μm to about 150 μm, and more specifically about 20 μm to about 100 μm. Within the above range, it can be used for a polarizing plate.

Although not shown in FIG. 1 , the protective layer 300 may be adhered to the polarizer by an adhesive layer. For example, the adhesive layer may be formed by at least one of a water-based adhesive and a photocurable adhesive. The adhesive layer may have a thickness of about 30 μm or less, for example, greater than about 0 μm and about 30 μm or less.

adhesive layer

The adhesive layer 400 may be formed on the lower surface of the protective layer 300 to adhere the polarizing plate to the adherend.

The adhesive layer 400 may be formed of a composition for an adhesive layer including an adhesive resin such as a (meth)acrylic adhesive resin, a silicone adhesive resin, a urethane adhesive resin, or an epoxy adhesive resin. Preferably, the adhesive layer 400 may be formed of a (meth)acrylic adhesive resin in consideration of the ease of manufacture of the adhesive layer. The (meth)acrylic adhesive resin may include an adhesive resin applied in a conventional composition known to those skilled in the art.

The adhesive layer 400 may have a thickness of about 5 μm to about 200 μm, specifically about 10 μm to about 150 μm, and more specifically about 20 μm to about 100 μm. Within the above range, it can be used for a polarizing plate.

Hereinafter, an optical display device according to an embodiment of the present invention will be described.

The optical display device includes the polarizing plate of the present invention. The optical display device may be a liquid crystal display device, an organic light emitting display device, a flexible organic light emitting display device, or the like, but is not limited thereto.

In one embodiment, the optical display device includes a polarizing plate of the present invention, a transparent adhesive film (eg, OCA) laminated on the upper surface of the polarizing plate, and a panel for an optical display formed on the lower surface of the polarizing plate, specifically an OLED panel. can

In another embodiment, the optical display device includes the polarizing plate of the present invention, a transparent adhesive film (eg, OCA) laminated on the upper surface of the polarizing plate, a cover glass laminated on the upper surface of the transparent adhesive film, and an optical formed on the lower surface of the polarizing plate It may include a panel for a display device.

Hereinafter, the configuration and operation of the present invention will be described in more detail through embodiments of the present invention. However, the following examples are provided to aid understanding of the present invention, and the scope of the present invention is not limited thereto.

Preparation Example 1

40 parts by weight of n-butyl acrylate, 5 parts by weight of 2-hydroxyethyl methacrylate, 50 parts by weight of methyl methacrylate, and 5 parts by weight of acrylic acid in a 1L reactor in which nitrogen gas is refluxed and a cooling device is installed to facilitate temperature control 100 parts by weight of a monomer mixture containing parts by weight was added, and 100 parts by weight of ethyl acetate was added as a solvent. Thereafter, nitrogen gas was introduced for 1 hour to remove oxygen to replace the inside of the reactor with nitrogen gas, and then the temperature of the reactor was maintained at 62°C. After uniformly stirring the monomer mixture, 0.03 parts by weight of azobisisobutyronitrile (AIBN) as a reaction initiator was added and reacted for 8 hours to prepare a (meth)acrylic copolymer having a weight average molecular weight of 200,000.

Preparation 2

100 parts by weight of a monomer mixture comprising 90 parts by weight of n-butyl acrylate, 5 parts by weight of 4-hydroxybutyl acrylate, and 5 parts by weight of acrylic acid in a 1 L reactor in which nitrogen gas is refluxed and a cooling device is installed to facilitate temperature control and 100 parts by weight of ethyl acetate as a solvent. Thereafter, nitrogen gas was introduced for 1 hour to remove oxygen to replace the reactor with nitrogen gas, and then the temperature of the reactor was maintained at 62°C. After uniformly stirring the monomer mixture, 0.03 parts by weight of azobisisobutyronitrile (AIBN) as a reaction initiator was added and reacted for 8 hours to prepare a (meth)acrylic copolymer having a weight average molecular weight of 200,000.

Hereinafter, specific specifications of the components used in Examples and Comparative Examples are as follows.

(A) Adhesive resin:

(A1) (meth)acrylic copolymer of Preparation Example 1

(A2) (meth)acrylic copolymer of Preparation Example 2

(B) isocyanate-based curing agent:

(B1) AE 700-100 (Asahi Kasehi, isocyanate-based curing agent)

(B2) Coronate L (Japanese polyurethane, trimethylolpropane adduct of toluene diisocyanate)

(C) UV absorber:

(C1) UV 3912 as a UV absorber (Orient Chemical, Indole-based)

(C2) Tinuvin 477 (BASF, triazine-based) as a UV absorber

(D) Silane coupling agent: KBM-403 (Shinyetsu, 3-glycidoxypropyl trimethoxysilane)

Example 1

A polyvinyl alcohol-based film washed with water (Kuraray, saponification degree: 99.5 mol%, degree of polymerization: 2000, thickness: 80 μm) was subjected to swelling treatment in a water swelling tank at 30°C. The polyvinyl alcohol-based film passed through the swelling tank was treated for 30 seconds to 200 seconds in a dyeing tank at 30° C. containing an aqueous solution containing 3% by weight of potassium iodide. The polyvinyl alcohol-based film passed through the dyeing tank was passed through a wet crosslinking tank containing 3 wt% of boric acid at 30 °C to 60 °C aqueous solution. A polarizer (thickness: 20 μm) was prepared by stretching the polyvinyl alcohol-based film passing through the crosslinking tank in an aqueous solution at 50° C. to 60° C. containing 3 wt% of boric acid, and stretching so that the total draw ratio was 6 times.

Based on the solid content, 100 parts by weight of the (meth)acrylic copolymer of Preparation Example 1, (B1) 30 parts by weight of an isocyanate-based curing agent, (C1) 1.5 parts by weight of a UV absorber, (D) 0.1 parts by weight of a silane coupling agent, solvent methylethyl A composition for a protective coating layer was prepared by mixing 20 parts by weight of ketone and stirring at 25° C. for 5 minutes.

On the upper surface of the prepared polarizer, the prepared composition for a protective coating layer was applied to a predetermined thickness, treated at 90° C. for 3 minutes to remove the solvent, and aged at 25° C. for 72 hours to form a protective coating layer on the upper surface of the polarizer (thickness: 7 μm) was formed.

After adhering a triacetylcellulose film (Fuji, n-TAC, thickness: 80㎛) to the lower surface of the polarizer with a water-based adhesive (including polyvinyl alcohol-based resin) as a protective film, on the other side of the triacetylcellulose film By forming an adhesive layer (thickness: 20 μm, (meth)acrylic adhesive layer), a polarizing plate laminated in the order of a protective coating layer-polarizer-adhesive layer-triacetyl cellulose film-adhesive layer was prepared. The adhesive layer was formed of a composition including a (meth)acrylic adhesive resin and an isocyanate-based curing agent.

Examples 2 to 5

A polarizing plate was manufactured in the same manner as in Example 1, except that each component and/or its content in the composition for a protective coating layer was changed as shown in Table 1 (unit: parts by weight) below. In Table 1 below, "-" means that the component is not included.

Comparative Examples 1 to 2

A pressure-sensitive adhesive composition for a polarizing plate was prepared in the same manner as in Example 1, except that each component and/or its content of the composition was changed as shown in Table 1 below.

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

(1) Modulus (unit: MPa): For the polarizing plates of Examples and Comparative Examples, the modulus was measured in terms of the protective coating layer. A specimen was prepared by cutting the polarizing plate in length x width (10 cm x 10 cm). The adhesive layer of the specimen is adhered to the glass plate to fix the specimen to the glass plate, and a micro indentor (Hysitron TI750 Ubi) is applied to the protective coating layer surface of the specimen at 25° C. with a constant force of 200 mN for 5 seconds, It was measured by holding for 2 seconds and calculating by relaxation for 5 seconds.

(2) Cracks of polarizer: The polarizing plates of Examples and Comparative Examples (no cracks in the polarizer) were cut to length x width (10 cm x 10 cm), the adhesive layer of the polarizer was laminated on a glass plate, and autoclaved at 50 ° C. and 1 atm. By processing, a specimen in which a polarizing plate is fixed to a glass plate was prepared. The specimen was left at -30°C for 30 minutes and left at 80°C for 30 minutes under a thermal shock chamber as one cycle, and 200 cycles were performed. After 200 cycles, the maximum length of cracks generated in the polarizer was measured. The crack is formed by the MD of the polarizer. If the crack length was 4 mm or less, it was evaluated as 'OK', and if the crack length was more than 4 mm, it was evaluated as 'NG'.

(3) Light transmittance of polarizing plate (unit: %): The polarizing plates of Examples and Comparative Examples were attached to a glass plate through an adhesive layer among the polarizing plates, and measured using a light transmittance measuring device V-7100 (JASCO). The light transmittance at double wavelengths of 380 nm and 405 nm was obtained.

(4) tackiness (unit: gf): a probe (cross-section is a cone-shaped curved surface with a radius of 2.5 mm and material is SUS) on the protective coating layer of the polarizing plates of Examples and Comparative Examples at 25°C for 10 seconds The force applied to the probe when the probe was detached from the surface of the protective coating layer was measured with a tack measuring device UTM (TA-Analyzer). It is preferable that the measured tackiness is 10 gf or less, for example, 0 gf to 10 gf.

(5) Warpage (unit: mm): The polarizing plates of Examples and Comparative Examples (MD of polarizer x TD of polarizer, 180mm x 110mm, rectangle) were mixed with a glass plate (width x length x thickness, 190mm x 120mm) through an adhesive layer among the polarizing plates. x 0.5T, rectangular) to prepare a specimen. The prepared specimen was put into an oven at 85° C. and taken out after 24 hours to measure the warpage of the specimen. The specimen was placed on a flat surface, a weight was placed above one edge, and the distance between the flat surface and the specimen was measured at a diagonal corner. If the distance between the flat place and the specimen was 0 mm or more and 2 mm or less, it was evaluated as ○, if it was more than 2 mm and less than 5 mm, △, if it was more than 5 mm, × was evaluated.

		Example					comparative example
		One	2	3	4	5	One	2
(A)	(A1)	100	100	100	100	100	100	-
	(A2)	-	-	-	-	-	-	100
(B)	(B1)	30	25	20	15	15	-	30
	(B2)	-	-	-	-	-	30	-
(C)	(C1)	1.5	1.5	1.5	1.5	-	1.5	1.5
	(C2)	-	-	-	-	1.5	-	-
(D)		0.1	0.1	0.1	0.1	0.1	0.1	0.1
Modulus (MPa)		10	15	18	22	22	0.1	0.01
crack		OK	OK	OK	OK	OK	NG	NG
light transmittance	380nm	0.2	0.2	0.2	0.2	1.5	0.2	0.2
light transmittance	405nm	2.6	2.5	2.4	2.5	2.5	2.4	2.5
Taekseong		10	9	8	5	5	8	62
warp		○	○	○	○	○	×	○

As shown in Table 1, the polarizing plate of the present invention provided a barrier effect to the polarizer and suppressed the bending of the polarizing plate.

On the other hand, the polarizing plate of the comparative example out of the modulus range of the present invention had no barrier effect on the polarizer, the bending inhibitory effect was weak, and the tackiness was not good.

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

Claims (20)

1. polarizer; a protective coating layer formed on the upper surface of the polarizer; A polarizing plate comprising a protective layer and an adhesive layer sequentially formed from the polarizer on a lower surface of the polarizer,

   The protective coating layer is formed of a thermosetting composition,

   The polarizing plate has a modulus measured by a micro-indenter on the surface of the protective coating layer of about 10 MPa or more.
2. The polarizing plate according to claim 1, wherein the protective coating layer is formed directly on an upper surface of the polarizer.
3. The polarizing plate according to claim 1, wherein only the protective coating layer as a protective layer of the polarizer is laminated on the upper surface of the polarizer.
4. The polarizing plate of claim 1, wherein the thermosetting composition comprises an adhesive resin, an isocyanate-based curing agent, and a UV absorber.
5. The polarizing plate according to claim 4, wherein the UV absorber is included in an amount of about 0.1 parts by weight to about 10 parts by weight based on 100 parts by weight of the adhesive resin.
6. The polarizing plate according to claim 4, wherein the UV absorber has a maximum absorption wavelength of about 390 nm or more.
7. The polarizing plate according to claim 4, wherein the UV absorber includes at least one of indole-based and triazine-based agents.
8. The method of claim 1, wherein the adhesive resin is a monomer mixture comprising a (meth)acrylic monomer having an alkyl group and a (meth)acrylic monomer having a hydroxyl group, and at least one of the monomers included in the monomer mixture is a homopolymer. A polarizing plate comprising a (meth)acrylic copolymer of a monomer mixture comprising a monomer having a glass transition temperature of about 50° C. or higher.
9. The polarizing plate according to claim 8, wherein the monomer having a glass transition temperature of about 50° C. or higher of the homopolymer is included in about 1 wt% to about 60 wt% of the monomer mixture.
10. The method according to claim 8, wherein the monomer having a glass transition temperature of about 50° C. or higher of the homopolymer is methyl methacrylate, t-butyl methacrylate, iso-propyl methacrylate, sec-butyl methacrylate, isobornyl methacrylate A polarizing plate comprising at least one of acrylates.
11. The method according to claim 8, wherein the monomer mixture comprises about 85 wt% to about 99.9 wt% of the (meth)acrylic monomer having an alkyl group, and about 0.1 wt% to about 15 wt% of the (meth)acrylic monomer having a hydroxyl group that is, a polarizer.
12. The polarizing plate of claim 8, wherein the monomer mixture further comprises a monomer having a carboxylic acid group.
13. 13. The method of claim 12, wherein the monomer mixture is about 70 wt% to about 98 wt% of the (meth)acrylic monomer having an alkyl group, about 0.1 wt% to about 15 wt% of the (meth)acrylic monomer having a hydroxyl group, and the carboxylic acid A polarizing plate comprising from about 0.1% to about 15% by weight of a monomer having a group.
14. The polarizing plate according to claim 4, wherein the isocyanate-based curing agent includes a polyisocyanate-based curing agent including a urethane bond and a plurality of units containing an alkylene group having 2 or more carbon atoms.
15. The polarizing plate according to claim 14, wherein the isocyanate-based curing agent includes a polyisocyanate curing agent having a plurality of units having the following formula (1):

    [Formula 1]

    *-R ¹ -O-(C=O)NH-R ² -NCO

    (In Formula 1, * is a connection site,

    R ¹ and R ² are the same or different and are a divalent aliphatic hydrocarbon group having 2 to 20 carbon atoms).
16. According to claim 4, 100 parts by weight of the adhesive resin, about 10 parts by weight to about 40 parts by weight of the isocyanate-based curing agent, and about 0.1 parts by weight to about 10 parts by weight of the UV absorber, the polarizing plate.
17. The polarizing plate according to claim 1, wherein the polarizing plate has a light transmittance of about 3% or less at a wavelength of 380 nm or 405 nm, respectively.
18. An optical display device comprising the polarizing plate of any one of claims 1 to 17.
19. The optical display device of claim 18 , wherein the optical display device includes the polarizing plate, a transparent adhesive film laminated on an upper surface of the polarizing plate, and an OLED panel formed on a lower surface of the polarizing plate.
20. The optical display device of claim 19 , wherein a cover glass is further laminated on an upper surface of the transparent adhesive film.

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