KR20230148725A - Polarizing Plate and Display Device Comprising the Same - Google Patents

Abstract

The present invention relates to an anti-reflection polarizing plate in which a substrate, a polarizer, a coated retardation layer, and an adhesive layer are sequentially stacked. Provided is the polarizing plate satisfying a specific mathematical formula 1 and an image display device including the same. The polarizing plate according to the present invention has excellent impact resistance despite being a thin film, and thus can suppress the occurrence of cracks in the polarizing plate even when subjected to external impact, and also has good cutting workability.

Description

Polarizing plate and image display device including the same {Polarizing Plate and Display Device Comprising the Same}

The present invention relates to a polarizing plate and an image display device including the same. More specifically, the present invention relates to a polarizing plate and an image display device including the same, which are thin and have excellent impact resistance, so that cracks in the polarizing plate can be suppressed even when subjected to external impact, and at the same time have good cutting processability, and an image display device including the same. It's about.

Organic light-emitting diode (OLED) panels may reflect external light such as sunlight and lighting due to electrode exposure, and the reflected external light may reduce visibility and contrast ratio, resulting in poor display quality.

Accordingly, as disclosed in Republic of Korea Patent Publication No. 2009-0122138, in order to block external light reflection on the surface and have black vision in the power-off state, a circular polarizer combining a linear polarizer and a λ/4 phase difference layer is used as an anti-reflection polarizer. It can be used by attaching it to the viewing side of the OLED panel.

Meanwhile, as interest in thinning image display devices has recently increased, there has been a demand for thinner related components, such as polarizers. Methods for thinning the polarizer include, for example, a method of thinning the polarizer itself or the protective film of the polarizer, a method of removing the protective film disposed between the polarizer and the OLED panel, and a method of using a liquid crystal compound in the retardation layer. I can hear it. However, in this case, there was a problem that cracks easily occurred in the polarizer due to external impact.

In addition, the polarizing plate must have good cutting processability so that it can be easily cut as needed when manufacturing or applying.

Republic of Korea Patent Publication No. 2009-0122138

One object of the present invention is to provide a polarizing plate that is thin and yet has excellent impact resistance, so that cracks in the polarizing plate can be suppressed even after external impact, and at the same time, has good cutting processability.

Another object of the present invention is to provide an image display device including the polarizing plate.

On the other hand, the present invention provides a polarizing plate in which a substrate, a polarizer, a coated retardation layer, and an adhesive layer are sequentially laminated, and satisfies the following equation 1.

[Equation 1]

610 ≤ A/B ≤ 730

In the above equation,

A is the elastic recovery rate (%) measured using a nano indenter when a load of 10 mN is applied to the polarizer for 20 seconds,

B is the shock absorption (gf·s) measured using an impact tester when a pen with a tip diameter of 1 mm and a weight of 5 g is dropped from a height of 50 mm on a polarizing plate.

In one embodiment of the present invention, the substrate is an acrylic substrate and may have a thickness of 15 to 25 μm.

In one embodiment of the present invention, the Martens hardness of the substrate may be 160 to 250 MPa when measured using a nano indenter by applying a load of 10 mN.

In one embodiment of the present invention, the coated retardation layer may include a λ/4 retardation layer.

In one embodiment of the present invention, the coated retardation layer is a λ/4 retardation layer, a retardation layer in which a λ/2 retardation layer and a λ/4 retardation layer are sequentially stacked from the viewing side, or a λ/4 retardation layer from the viewing side. 4 The phase contrast layer and the positive C plate layer may be sequentially laminated.

In one embodiment of the present invention, the adhesive layer is formed from a thermosetting acrylic adhesive composition and may have a thickness of 20 to 100 ㎛.

In one embodiment of the present invention, the storage modulus (G') of the adhesive layer may be 0.070 MPa or less at 25°C.

In one embodiment of the present invention, the Martens hardness of the polarizing plate may be 30 to 37 MPa when measured using a nano indenter by applying a load of 10 mN.

The polarizing plate according to an embodiment of the present invention may be used for flexible use.

On the other hand, the present invention provides an image display device including the polarizing plate.

Although the polarizing plate according to the present invention is a thin film, it has excellent impact resistance. The occurrence of cracks in the polarizing plate can be suppressed even after external impact, and at the same time, it has good cutting processability.

1 is a schematic cross-sectional view of a polarizer according to an embodiment of the present invention.
Figure 2 is a schematic cross-sectional view of an image display device according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail.

The present invention relates to a polarizing plate in which a substrate, a polarizer, a coated retardation layer, and an adhesive layer are sequentially laminated, and satisfies the following equation (1).

[Equation 1]

610 ≤ A/B ≤ 730

In the above equation,

A is the elastic recovery rate (%) measured using a nano indenter when a load of 10 mN is applied to the polarizer for 20 seconds,

B is the shock absorption (gf·s) measured using an impact tester when a pen with a tip diameter of 1 mm and a weight of 5 g is dropped from a height of 50 mm on a polarizing plate.

A nano indenter is a device that measures mechanical properties such as hardness and elastic recovery rate by analyzing the load-displacement curve obtained in the process of applying and removing a certain load to the surface of a material.

The elastic recovery rate (%) is a value (nIT, elastic work ratio) measured with a nano indenter by applying a load of 10 mN for 20 seconds.

The shock absorption amount (gf·s) is a value measured using an impact tester, and is the product of the force (gf) transmitted to the lower part during impact and the contact time (s).

In the present invention, if the A/B value is less than 610, it may be vulnerable to damage from external impact, and if the A/B value is more than 730, cutting processing may be difficult.

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

Referring to FIG. 1, the polarizing plate 100 according to an embodiment of the present invention includes a substrate 110, a polarizer 120, a coated retardation layer 130, and an adhesive layer 140 that are sequentially stacked. . At this time, the substrate 110 is located on the viewing side.

In one embodiment of the present invention, the substrate 110 is a layer that serves as a support layer for the polarizer 120, the coated retardation layer 130, and the adhesive layer 140.

In one embodiment of the present invention, it is preferable to use an acrylic base material in order to satisfy the above-mentioned A/B values.

The acrylic substrate may be formed of an acrylic resin such as polymethyl (meth)acrylate or polyethyl (meth)acrylate.

In one embodiment of the present invention, the thickness of the substrate may be 15 to 25 μm. If the thickness of the substrate is less than 15㎛, impact resistance may be reduced, and if it is more than 25㎛, bending resistance may deteriorate.

The Martens hardness of the substrate may be 160 to 250 MPa when measured using a nano indenter by applying a load of 10 mN. If the Martens hardness of the substrate is less than 160 MPa, impact resistance may be reduced, and if it is more than 250 MPa, bending resistance may deteriorate.

In one embodiment of the present invention, the polarizer 120 is manufactured by dyeing and aligning a hydrophilic polymer film with iodine or a dichroic dye. Examples of the hydrophilic polymer film include polyvinyl alcohol-based film and partially saponified polyvinyl alcohol-based film. etc. are used.

Polyvinyl alcohol-based films typically have a degree of polymerization of 500 to 10,000, preferably 1,000 to 6,000, and more preferably 1,400 to 4,000. In the case of saponified polyvinyl alcohol-based films, the degree of saponification is determined by the solubility of the polyvinyl alcohol-based film. In terms of use, preferably 95.0 mol% or more, more preferably 99.0 mol% or more, and even more preferably 99.9 mol% or more can be used.

The types of hydrophilic polymer films are not particularly limited as long as they are films that can be dyed with iodine or dichroic dyes, in addition to polyvinyl alcohol-based films. For example, hydrophilic polymer films such as polyethylene terephthalate film, ethylene-vinyl acetate copolymer film, ethylene-vinyl alcohol copolymer film, cellulose film and partially saponified films thereof, and dehydrated polyvinyl alcohol-based film. and polyene oriented films such as polyvinyl chloride treated with dehydrochloric acid can be used.

The thickness of the polarizer 120 is not particularly limited, but is, for example, in the range of 2 to 40 μm, preferably in the range of 2 to 30 μm, and more preferably in the range of 5 to 10 μm. If the thickness of the polarizer 120 is within the above range, the polarizer can be thinned and the shrinkage force due to contraction/expansion of the polarizer in a dry/humid environment can be reduced, thereby minimizing the occurrence of curl.

The polarizer 120 may be bonded to the substrate 110 via an adhesive layer (not shown).

The surface of the substrate 110 that is bonded to the polarizer may be treated for bonding. Treatments that facilitate bonding include dry treatments such as primer treatment, plasma treatment, and corona treatment, chemical treatments such as alkali treatment (saponification treatment), and coating treatments that easily form an adhesive layer.

Any suitable adhesive may be used as the adhesive, and materials having excellent transparency, thermal stability, low birefringence, etc. are preferred. Specific examples include water-based adhesives, thermoplastic adhesives, hot-melt adhesives, rubber-based adhesives, thermoset adhesives, monomer-reactive adhesives, inorganic adhesives, and natural adhesives. Preferred examples include, from the viewpoint of excellent optical transparency, weather resistance, and heat resistance, monomer reactive adhesive "Takenate 631" (trade name, manufactured by Mitsui Takeda Chemicals) containing aliphatic isocyanate as a main component; and a water-based adhesive "GOHSEFIMER Z Series" (trade name, manufactured by Nippon Synthetic Chemical Industry) containing denatured polyvinyl alcohol having an acetoacetyl group as a main component.

The thickness of the adhesive layer may be appropriately determined depending on the type of resin acting as an adhesive, adhesive strength, environment in which the adhesive is used, etc. The adhesive layer preferably has a thickness of 0.01 μm to 50 μm, more preferably 0.05 μm to 20 μm, and even more preferably 0.1 μm to 10 μm.

The bonding method may be a conventional method in the field, for example, bonding of a polarizer or protective layer using a flexible method, Meyer bar coating method, gravure coating method, die coating method, dip coating method, spray coating method, etc. A method of applying an adhesive composition to a surface and then joining them is an example. The stretching method is a method of applying the adhesive composition to the bonding surface while moving the polarizer or the protective layer generally vertically, horizontally, or in an inclined direction between the two. After applying the adhesive composition, the polarizer or protective layer is sandwiched between the niprolls and the like to bond them.

After bonding, drying treatment may be performed. The drying treatment after bonding can be performed, for example, by spraying hot air.

After drying, it is preferable to cure for about 12 to 600 hours at room temperature or a slightly higher temperature, for example, 20 to 50°C.

In one embodiment of the present invention, the polarizer 120 and the coated retardation layer 130 may be bonded by an adhesive layer (not shown).

The adhesive layer between the polarizer 120 and the coated retardation layer 130 may be preferably formed from a thermosetting acrylic adhesive composition in terms of impact resistance and cutting processability.

The adhesive layer between the polarizer 120 and the coated retardation layer 130 may have a thickness of 2 to 10 ㎛. If the thickness of the adhesive layer between the polarizer 120 and the coated retardation layer 130 is less than 2 ㎛, adhesive strength may be reduced, and if it is more than 10 ㎛, bending resistance may be reduced.

In one embodiment of the present invention, the coated retardation layer 130 may include a λ/4 retardation layer.

The λ/4 phase contrast layer can convert incident linearly polarized light into elliptically polarized light or circularly polarized light, and conversely convert incident elliptically polarized light or circularly polarized light into linearly polarized light. Accordingly, the λ/4 phase difference layer can be applied to the OLED panel to prevent reflection of external light, thereby creating a black visual experience in a power-off state.

The λ/4 retardation layer may have an in-plane retardation value (Re) of 120 nm to 170 nm at a wavelength of 550 nm.

The λ/4 phase difference layer may have a thickness direction retardation value (Rth) of -150 nm to 150 nm, preferably -100 nm to 100 nm.

The thickness of the λ/4 phase difference layer may be 0.5 to 10 μm, preferably 0.5 to 5 μm. When the thickness of the λ/4 phase difference layer is within the above range, it is possible to reduce the thickness along with improving anti-reflection performance.

The phase difference layer 130 may have a single-layer structure or a multi-layer structure in which two or more layers are stacked. When the phase difference layer has a single-layer structure, the phase difference layer may be made of a λ/4 phase difference layer. When the retardation layer has a multi-layer structure, the retardation layer essentially includes a λ/4 retardation layer, and may additionally include one or more of a λ/2 retardation layer and a positive C plate layer. At this time, each layer may be attached via an adhesive layer (not shown).

The adhesive layer may preferably be formed from a UV-curable epoxy-based adhesive or a UV-curable acrylic adhesive composition in terms of impact resistance and cutting processability.

The adhesive layer may have a thickness of 2 to 10 ㎛. If the thickness of the adhesive layer is less than 2 ㎛, adhesive strength may be reduced, and if it is more than 10 ㎛, bending resistance may be reduced.

The λ/2 retardation layer and the positive C plate layer can be used to improve the black visibility of the reflected color.

For example, the coated retardation layer has a structure in which a λ/2 retardation layer and a λ/4 retardation layer are sequentially stacked from the viewing side, or a λ/4 retardation layer and a positive C plate layer are formed from the viewing side. It may have a sequentially stacked structure.

The λ/2 phase difference layer provides a phase difference of π (=λ/2) in the electric field oscillation direction (polarization plane) of the incident light, and can be used to improve the black visibility of the reflected color.

The λ/2 retardation layer may have an in-plane retardation value (Re) of 210 nm to 300 nm, preferably 220 nm to 290 nm, at a wavelength of 550 nm.

The λ/2 phase difference layer may have a thickness direction retardation value (Rth) of -150 nm to 150 nm, preferably -100 nm to 100 nm.

The thickness of the λ/2 phase difference layer may be 0.5 to 10 μm, preferably 0.5 to 5 μm. When the thickness of the λ/2 phase difference layer is within the above range, it is possible to reduce the thickness along with improving anti-reflection performance.

The positive C plate layer ideally includes a case where the refractive index ratio (Nz) is negative and infinite, but is substantially -6 or less. Accordingly, the positive C plate layer may have a thickness direction retardation value (Rth) of -190 to -10 nm. If the thickness direction retardation value is less than -190 nm or more than -10 nm, the effect of improving the reflected color may be minimal. In addition, the front phase difference value (Ro) should ideally be 0 nm, but is included in the present invention to the extent that it can be considered as 0 nm in practice. For example, the front phase difference value (Ro) may be -1 to 1 nm.

The thickness of the positive C plate layer may be 0.5 to 20 μm, preferably 0.5 to 5 μm. When the thickness of the positive C plate layer is within the above range, it is possible to reduce the thickness along with improving anti-reflection performance.

The λ/4 retardation layer, λ/2 retardation layer, and positive C plate layer may have reverse wavelength, forward wavelength, or flat wavelength dispersion, respectively.

The reverse wavelength dispersion means that the in-plane retardation increases as the wavelength increases from 450 nm to 650 nm.

The constant wavelength dispersion means that the in-plane retardation decreases as the wavelength increases from 450 nm to 650 nm.

The flat wavelength dispersion means that the in-plane retardation does not substantially increase or decrease as the wavelength increases from 450 nm to 650 nm.

The thickness of the coated retardation layer 130 may be 0.5 to 40 μm, preferably 1.5 to 15 μm, and more preferably 1.5 to 10 μm. If the sum of the thicknesses is less than 0.5㎛, the retardation value cannot be sufficiently expressed or there is a risk of cracks occurring due to external shock. On the other hand, if it is more than 40㎛, thinning of the entire polarizer may be limited.

The coated retardation layer 130 includes a liquid crystal compound.

For example, the liquid crystal compound may have optical anisotropy and may be reactive to light or heat.

The type of the liquid crystal compound is not particularly limited, but can be classified into rod-shaped type (rod-shaped liquid crystal compound) and disk-shaped type (disk-shaped liquid crystal compound, discotic liquid crystal compound) based on its shape. Additionally, there are low molecule type and high molecule type. In the present invention, any liquid crystal compound can be used. Two or more types of rod-shaped liquid crystal compounds, two or more types of disc-shaped liquid crystal compounds, or a mixture of a rod-shaped liquid crystal compound and a disc-shaped liquid crystal compound may be used.

In particular, the liquid crystal compound is more preferably formed using a liquid crystal compound having a polymerizable group (rod-shaped liquid crystal compound or disc-shaped liquid crystal compound) because it can reduce temperature and/or humidity changes in optical properties. The liquid crystal compound may be a mixture of two or more types, and in that case, it is preferable that at least one has two or more polymerizable groups.

That is, the coated retardation layer 130 is preferably a layer formed by fixing a rod-shaped liquid crystal compound having a polymerizable group or a disk-shaped liquid crystal compound having a polymerizable group by polymerization. In this case, after becoming a layer, the liquid crystal no longer forms. There is no need to indicate your last name.

The type of polymerizable group contained in the rod-shaped liquid crystal compound or disk-shaped liquid crystal compound is not particularly limited, and a functional group capable of addition polymerization is preferred, and a polymerizable ethylenically unsaturated group or ring-polymerizable group is preferred. More specifically, (meth)acryloyl group, vinyl group, styryl group, and allyl group are preferably used, and (meth)acryloyl group is more preferable. The (meth)acryloyl group is a concept that includes both methacryloyl group and acryloyl group.

The coated retardation layer 130 may be formed from a composition for forming a retardation layer containing the liquid crystal compound.

The composition for forming a phase contrast layer may contain components other than the liquid crystal compound described above.

For example, the composition may contain a polymerization initiator. The polymerization initiator used is selected depending on the type of polymerization reaction, and examples include a thermal polymerization initiator and a photopolymerization initiator. For example, photopolymerization initiators include α-carbonyl compounds, acyloinethers, α-hydrocarbon substituted aromatic acyloin compounds, polynuclear quinone compounds, and combinations of triarylimidazole dimer and p-aminophenyl ketone. etc. can be mentioned.

The amount of the polymerization initiator used is preferably 0.01 to 20% by weight, more preferably 0.5 to 5% by weight, based on the total solid content of the composition.

Additionally, the composition may include a polymerizable monomer in terms of uniformity and strength of the coating film.

Polymerizable monomers include radically polymerizable or cationically polymerizable compounds, preferably polyfunctional radically polymerizable monomers. Additionally, the polymerizable monomer is preferably copolymerizable with the liquid crystal compound containing the polymerizable group.

The amount of polymerizable monomer used is preferably 1 to 50% by weight, more preferably 2 to 30% by weight, based on the total weight of the liquid crystal compound.

In addition, the composition may include a surfactant in terms of uniformity and strength of the coating film.

Although known compounds can be used as the surfactant, fluorine-based compounds are particularly preferable.

Additionally, the composition may contain a solvent, and an organic solvent is preferably used. Organic solvents include, for example, amides (e.g., N,N-dimethylformamide), sulfoxides (e.g., dimethyl sulfoxide), heterocyclic compounds (e.g., pyridine), hydrocarbons (e.g., benzene, hexane), Alkyl halides (e.g. chloroform, dichloromethane), esters (e.g. methyl acetate, ethyl acetate, butyl acetate), ketones (e.g. acetone, methyl ethyl ketone), ethers (e.g. tetrahydrofuran, 1,2-dimethoxy) ethane) can be mentioned. Among them, alkyl halides and ketones are preferable. You may use two or more types of organic solvents together.

The coated retardation layer 130 can be formed by applying the composition for forming a retardation layer to form a coating film and performing a curing treatment (irradiation of ultraviolet rays (light irradiation treatment) or heat treatment) on the obtained coating film.

The composition can be applied by known methods, such as wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, and die coating.

In one embodiment of the present invention, the adhesive layer 140 located on the side opposite to the viewing side of the coated retardation layer 130 serves to attach the polarizer 100 to the OLED panel 10. Alternatively, the adhesive layer 140 may attach the polarizer 100 to a touch panel (not shown).

The adhesive layer 140 may be formed from a thermosetting acrylic adhesive composition.

The thermosetting acrylic adhesive composition may include a (meth)acrylic copolymer having a crosslinkable functional group and a crosslinking agent.

The (meth)acrylic copolymer having a crosslinkable functional group is a component that plays a role in controlling the viscosity-elasticity balance of the adhesive composition, and is composed of a (meth)acrylic monomer having an alkyl group of 1 to 14 carbon atoms and a monomer having a crosslinkable functional group. It may be a copolymer. Here, (meth)acrylic means acrylic and/or methacrylic.

Specific examples of the (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms include n-butyl (meth)acrylate, 2-butyl (meth)acrylate, t-butyl (meth)acrylate, and 2-ethylhexyl. (meth)acrylate, ethyl (meth)acrylate, methyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, pentyl (meth)acrylate, n-octyl (meth) Acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, n-tridecyl (meth)acrylate, n-tetradecyl (meth) Acrylates and the like can be mentioned, and among these, n-butylacrylate is preferable in terms of controlling the A/B values described above. These can be used alone or in combination of two or more types.

The (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms is preferably contained in an amount of 80 to 99% by weight based on 100% by weight of the total monomer. If the content is less than 80% by weight, the adhesive strength may not be sufficient, and if the content is more than 99% by weight, the cohesion may be reduced.

The monomer having the crosslinkable functional group is a component for reinforcing the cohesion or adhesive strength of the adhesive composition through chemical bonding to provide durability and cutting properties, for example, a monomer with a carboxyl group, a monomer with a hydroxy group, and a monomer with an amide group. , a monomer having a tertiary amine group, etc. Among these, a mixture of a monomer having a carboxyl group and a monomer having a hydroxy group is preferable in terms of controlling the A/B value described above. These can be used individually or in combination of two or more types.

Monomers having the carboxyl group include monobasic acids such as (meth)acrylic acid, crotonic acid, and 2-carboxyethyl acrylate; Dibasic acids such as maleic acid, itaconic acid, and fumaric acid, and their monoalkyl esters; 3-(meth)acryloylpropionic acid; Succinic anhydride ring-opening adduct of 2-hydroxyalkyl (meth)acrylate where the alkyl group has 2-3 carbon atoms; Succinic anhydride ring-opening adduct of hydroxyalkylene glycol (meth)acrylate where the alkylene group has 2 to 4 carbon atoms; Examples include compounds obtained by ring-opening addition of succinic anhydride to the caprolactone adduct of 2-hydroxyalkyl (meth)acrylate having 2-3 carbon atoms in the alkyl group, and among these, (meth)acrylic acid has the A/B value described above. This is desirable in terms of control.

Monomers having the hydroxy group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. , 6-hydroxyhexyl (meth)acrylate, 2-hydroxyethylene glycol (meth)acrylate, 2-hydroxypropylene glycol (meth)acrylate, hydroxyalkylene glycol with 2-4 carbon atoms in the alkylene group. (meth)acrylate, 4-hydroxybutyl vinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, 7-hydroxyheptyl vinyl ether, 8-hydroxyoctyl vinyl ether, 9-hydroxy Examples include nonyl vinyl ether and 10-hydroxydecyl vinyl ether, and among these, 2-hydroxyethyl (meth)acrylate is preferable in terms of controlling the A/B value described above.

Monomers having the amide group include (meth)acrylamide, N-isopropylacrylamide, and N-tertiary butylacrylamide.

Monomers having the tertiary amine group include N,N-(dimethylamino)ethyl(meth)acrylate, N,N-(diethylamino)ethyl(meth)acrylate, and N,N-(dimethylamino)propyl ( Meta)acrylate, etc. can be mentioned.

The monomer having the crosslinkable functional group may be included in an amount of 0.05 to 15% by weight based on 100% by weight of the total monomer. If the content of the monomer having the crosslinkable functional group is less than 0.05% by weight, the cohesive force of the adhesive may decrease and the peeling force may increase, and if it is more than 15% by weight, the adhesive strength may decrease and durability may decrease due to the high gel fraction. You can.

The (meth)acrylic copolymer having the crosslinkable functional group further contains other polymerizable monomers in addition to the above monomers in a range that does not deteriorate physical properties such as adhesion, durability, and adhesion, for example, 10% by weight or less based on the total amount of monomers. can do.

The method for producing the (meth)acrylic copolymer is not particularly limited, and may be produced using methods commonly used in the field, such as bulk polymerization, solution polymerization, emulsion polymerization, or suspension polymerization, and solution polymerization is preferred. . Additionally, commonly used solvents, polymerization initiators, and chain transfer agents for molecular weight control can be used during polymerization.

The (meth)acrylic copolymer usually has a weight average molecular weight (polystyrene conversion, Mw) of 50,000 to 2 million, preferably 300,000 to 1.3 million, as measured by gel permeation chromatography (GPC). . If the weight average molecular weight is less than 50,000, cohesion between copolymers may be insufficient, which may cause problems with adhesive durability. If the weight average molecular weight is more than 2 million, a large amount of diluting solvent may be required to ensure fairness during coating.

The crosslinking agent is a component that can improve adhesion and durability, and maintain reliability and shape of the adhesive at high temperatures. Specifically, the crosslinking agent may be an isocyanate-based, epoxy-based, peroxide-based, metal chelate-based, oxazoline-based, etc., and one type or a mixture of two or more types may be used. Among these, isocyanate-based is preferable in terms of controlling the A/B values described above.

Specifically, the crosslinking agent includes tolylene diisocyanate, xylene diisocyanate, 2,4-diphenylmethane diisocyanate, 4,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and tetramethylxylene diisocyanate. , diisocyanate compounds such as naphthalene diisocyanate; An adduct obtained by reacting 3 moles of a diisocyanate compound with 1 mole of a polyhydric alcohol compound such as trimethylolpropane, an isocyanurate obtained by self-condensing 3 moles of a diisocyanate compound, and a diisocyanate obtained from 2 moles of 3 moles of a diisocyanate compound. Polyfunctional isocyanate compounds containing three functional groups such as biuret, triphenylmethane triisocyanate, and methylene bistriisocyanate, in which the remaining 1 mole of diisocyanate is condensed with urea, can be used. Polyfunctional isocyanate compounds containing three functional groups can be used. An isocyanate compound, especially an isocyanurate obtained by self-condensing 3 moles of a diisocyanate compound, is preferable in terms of controlling the A/B value described above. These can be used individually or in combination of two or more types.

The crosslinking agent may be included in an amount of 0.1 to 0.5 parts by weight, preferably 0.3 to 0.5 parts by weight, based on 100 parts by weight of the (meth)acrylic copolymer having the crosslinkable functional group. If the content of the crosslinking agent is less than 0.1 part by weight, adhesive strength or cohesion may be reduced, and if it exceeds 0.5 part by weight, the storage modulus of the adhesive may increase and may deviate from the above-mentioned A/B value range.

In addition to the components mentioned above, the thermosetting acrylic adhesive composition contains a plasticizer, a silane coupling agent, a tackifying resin, an antioxidant, and a corrosion inhibitor in order to control the adhesion, cohesion, viscosity, modulus of elasticity, glass transition temperature, etc. required depending on the application. , leveling agents, surface lubricants, dyes, pigments, anti-foaming agents, fillers, light stabilizers, etc. may be further included.

The adhesive layer can be formed by coating the above-described thermosetting acrylic adhesive composition on a single base film. The coating method is not particularly limited as long as it is a method known in the field, and for example, bar coater, air knife, gravure, reverse roll, kiss roll, spray, blade, die coater, casting, spin coating, etc. can be used. . Specifically, the adhesive layer can be formed by applying a thermosetting acrylic adhesive composition on one base film, drying and curing at 30 to 150°C for 1 second to 2 hours, preferably 5 seconds to 1 hour. .

The base film may include polyolefin-based film, polyester-based film, acrylic-based film, styrene-based film, amide-based film, polyvinyl chloride film, polyvinylidene chloride film, polycarbonate film, etc., and these include silicone-based, fluorine-based, and silica films. It may have been appropriately released using powder or the like.

The adhesive layer 140 may have a thickness of 20 to 100 ㎛. If the thickness of the adhesive layer 140 is less than 20 ㎛, impact resistance may be reduced, and if it is more than 100 ㎛, cutting processing may be difficult.

The storage modulus (G') of the adhesive layer 140 may be 0.070 MPa or less at 25°C. If the storage modulus (G') of the adhesive layer 140 at 25°C is greater than 0.070 MPa, impact resistance and bending resistance may deteriorate.

In one embodiment of the present invention, the Martens hardness of the polarizing plate may be 30 to 37 MPa, preferably 35 to 37 MPa, when measured using a nano indenter by applying a load of 10 mN. If the Martens hardness of the polarizer is less than 30 MPa, impact resistance may be reduced, and if it is more than 37 MPa, bending resistance may be deteriorated.

The polarizing plate according to the present invention satisfies Equation 1 above by controlling the type and thickness of the substrate 110 and the adhesive layer 140, so that not only can the polarizing plate be thinner and improve impact resistance, but also have good cutting processability. .

In particular, the polarizer according to one embodiment of the present invention can be advantageously applied to a flexible display and can be used to prevent reflection.

In the polarizing plate according to an embodiment of the present invention, a peelable protective film (not shown) may be laminated on the visible side of the substrate 110.

The peelable protective film includes a base film and an adhesive layer formed on one side of the base film.

Base films of the protective film include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; Alternatively, polyolefin films such as polypropylene or polyethylene may be mentioned. The adhesives exemplified above can be used as materials for the adhesive layer.

The thickness of the protective film may be 10 to 150 μm, preferably 25 to 130 μm. If the thickness of the protective film is less than 10㎛, peeling of the protective film may not be easy, and if it is more than 150㎛, adhesion to a polarizer provided with a protective layer may be reduced.

Additionally, in the polarizing plate according to an embodiment of the present invention, a release film may be further laminated on the surface opposite to the viewing side of the adhesive layer 140.

The release film is removed when attaching the polarizer to the OLED panel or touch panel.

Base materials for the release film include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; Alternatively, polyolefin films such as polypropylene or polyethylene may be mentioned.

The surface of the base material of the release film in contact with the adhesive layer 140 may be subjected to release treatment. The release treatment may use a release agent such as a silicone-based release agent, a fluorine-based release agent, or a long-chain alkyl graft polymer-based release agent, or a surface treatment method using plasma treatment.

The thickness of the release film may be 10 to 150 μm, preferably 25 to 130 μm. If the thickness of the release film is less than 10㎛, it may not be easy to peel, and if it is more than 150㎛, adhesion to the adhesive layer 140 may be reduced.

The total thickness of the polarizing plate according to an embodiment of the present invention may be 200 μm or less, for example, 20 to 150 μm, preferably 25 to 100 μm, and more preferably 30 to 90 μm. At this time, the total thickness of the polarizing plate is the thickness excluding the thickness of the peelable protective film and the peeling film.

One embodiment of the present invention relates to an image display device including the polarizing plate 100.

Referring to FIG. 2, an image display device according to an embodiment of the present invention includes the polarizing plate 100; and

It includes an OLED panel 10 laminated on a surface opposite to the viewing side of the polarizer 100.

In addition, the image display device according to an embodiment of the present invention may include a cover window 30 attached to the viewing side of the polarizing plate 100 via a transparent adhesive layer 20, as shown in FIG. 2. .

The transparent adhesive layer 20 may include, for example, an adhesive such as an optically clear adhesive (OCA) or an optically clear resin (OCR).

The cover window 30 may be made of a material that is durable against external impact and transparent enough for the user to see. For example, the cover window 30 may be glass or a flexible polymer film. The glass may include a glass material with flexible properties. For example, the flexible polymer film includes polyimide (PI), polyamideimide, polyethersulphone (PES), polyacrylate (PAR), and polyetherimide (PEI). , polyethylene napthalate (PEN), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyarylate, polycarbonate (PC), cellulose triacetate (cellulose triacetate, TAC), cellulose acetate propionate (CAP), etc. The flexible polymer film may have a hard coating layer formed on at least one side. The hard coating layer may be formed using a hard coating composition known in the art.

An image display device according to an embodiment of the present invention may be an organic EL display device and may be in the form of a typical flat panel display, flexible display, or foldable display.

Hereinafter, the present invention will be described in more detail through examples and experimental examples. These examples and experimental examples are only for illustrating the present invention, and it is obvious to those skilled in the art that the scope of the present invention is not limited thereto.

Preparation Example 1: Preparation of polarizer

A 30㎛ thick polyvinyl alcohol resin film (Kuraray) with an average degree of polymerization of about 2,400 and a degree of hydrolysis of 99.9 mol% or more was immersed in distilled water to swell, and then an aqueous solution containing potassium iodide/boric acid/water mixed at a weight ratio of 10/5/100. It was uniaxially stretched about 5 times while being immersed at 53°C for 1 minute. Then, it was washed with pure water at 15°C for 1.5 seconds and then dried at 50°C for 5 minutes to prepare a polarizer with a thickness of 8 μm in which iodine was adsorbed and oriented on polyvinyl alcohol.

Synthesis Example 1: Synthesis of acrylic copolymer

A 4-neck jacket reactor (1L) was equipped with a stirrer, thermometer, reflux cooling pipe, dropping lot, and nitrogen gas introduction pipe, and nitrogen gas was introduced into the reactor to replace it, and then 120 parts by weight of ethyl acetate, n -98.1 parts by weight of butylacrylate (n-BA), 0.5 parts by weight of acrylic acid (AA), and 1.4 parts by weight of 2-hydroxyethyl acrylate (2-HEA) were added, and the external temperature of the reactor was raised to 50°C. Next, a solution in which 0.1 parts by weight of 2,2'-azobisisobutyronitrile (AIBN) was completely dissolved in 10 parts by weight of ethyl acetate was added dropwise to the reactor. After reacting for an additional 5 hours while maintaining the external temperature of the jacket at 50°C, 90 parts by weight of ethyl acetate was slowly added dropwise using a dropping funnel over 1 hour. Subsequently, the reaction was performed for an additional 5 hours while maintaining the external temperature of the jacket at 50°C to obtain an acrylic copolymer with a weight average molecular weight of approximately 1,000,000.

Preparation Example 2: Preparation of thermosetting acrylic adhesive sheet (A-1)

100 parts by weight of the acrylic copolymer prepared in Synthesis Example 1, 0.5 parts by weight of a trifunctional isocyanate compound (triglycidyl isocyanurate, I0428, manufactured by TCI) as a crosslinking agent, and 3-glycidoxypropyl tri as a silane coupling agent. 0.15 parts by weight of methoxysilane (KBM-403) was dissolved in ethyl acetate solvent to prepare an adhesive composition with a solid content of 40% by weight.

The prepared adhesive composition was applied to a PET film coated with a release agent using an applicator to a thickness of 50㎛ after drying, and dried in a forced circulation hot air dryer in a 100°C oven for 20 minutes to prepare an adhesive sheet.

Preparation Example 3: Preparation of thermosetting acrylic adhesive sheet (A-2)

100 parts by weight of the acrylic copolymer prepared in Synthesis Example 1, 0.6 parts by weight of a trifunctional isocyanate compound (triglycidyl isocyanurate, I0428, manufactured by TCI) as a crosslinking agent, and 3-glycidoxypropyl tri as a silane coupling agent. 0.15 parts by weight of methoxysilane (KBM-403) was dissolved in ethyl acetate solvent to prepare an adhesive composition with a solid content of 40% by weight.

The prepared adhesive composition was applied to a PET film coated with a release agent using an applicator to a thickness of 50㎛ after drying, and dried in a forced circulation hot air dryer in a 100°C oven for 20 minutes to prepare an adhesive sheet.

Preparation Example 4: Preparation of thermosetting acrylic adhesive sheet (A-3)

100 parts by weight of the acrylic copolymer prepared in Synthesis Example 1, 0.4 parts by weight of a trifunctional isocyanate compound (triglycidyl isocyanurate, I0428, manufactured by TCI) as a crosslinking agent, and 3-glycidoxypropyl tri as a silane coupling agent. 0.15 parts by weight of methoxysilane (KBM-403) was dissolved in ethyl acetate solvent to prepare an adhesive composition with a solid content of 40% by weight.

The prepared adhesive composition was applied to a PET film coated with a release agent using an applicator to a thickness of 50㎛ after drying, and dried in a forced circulation hot air dryer in a 100°C oven for 20 minutes to prepare an adhesive sheet.

Preparation Example 5: Preparation of thermosetting acrylic adhesive sheet (A-4)

100 parts by weight of the acrylic copolymer prepared in Synthesis Example 1, 0.4 parts by weight of a trifunctional isocyanate compound (triglycidyl isocyanurate, I0428, manufactured by TCI) as a crosslinking agent, and 3-glycidoxypropyl tri as a silane coupling agent. 0.15 parts by weight of methoxysilane (KBM-403) was dissolved in ethyl acetate solvent to prepare an adhesive composition with a solid content of 40% by weight.

The prepared adhesive composition was applied to a PET film coated with a release agent using an applicator to a thickness of 25㎛ after drying, and dried in a forced circulation hot air dryer in a 100°C oven for 10 minutes to prepare an adhesive sheet.

Example 1: Production of polarizer

A polarizing plate was manufactured with the same structure as the embodiment of FIG. 1 according to the following method.

An acrylic film with a thickness of 20 μm was bonded to the viewing side of the polarizer prepared in Preparation Example 1 as a substrate using a water-based adhesive. At this time, thermosetting water-based PVA adhesive was used as the water-based adhesive. The water-based adhesive was cured by drying in an oven at 60°C for 5 minutes. Afterwards, a λ/2 retardation layer (discotic liquid crystal layer) with a thickness of 2.0 μm was bonded to the polarizer equipped with the above substrate as a first retardation layer using a thermosetting acrylic adhesive (Lintec) with a thickness of 5 μm, and 2 As a phase contrast layer, a λ/4 phase contrast layer (nematic liquid crystal layer) with a thickness of 1.0 μm was bonded using a UV-curable epoxy adhesive (Daikin, UV-1100) with a thickness of 2 μm. An adhesive layer 140 was bonded to the opposite side of the λ/4 phase difference layer on the viewing side. At this time, the adhesive layer 140 was formed by bonding the thermosetting acrylic adhesive sheet (A-1) of Preparation Example 2 to the opposite side of the viewing side of the λ/4 phase difference layer and peeling off the PET film.

Example 2: Production of polarizer

A polarizing plate was manufactured with the same structure as the embodiment of FIG. 1 according to the following method.

An acrylic film with a thickness of 18 μm was bonded to the viewing side of the polarizer prepared in Preparation Example 1 as a substrate using a water-based adhesive. At this time, thermosetting water-based PVA adhesive was used as the water-based adhesive. The water-based adhesive was cured by drying in an oven at 60°C for 5 minutes. Afterwards, a λ/2 retardation layer (discotic liquid crystal layer) with a thickness of 2.0 μm was bonded to the polarizer equipped with the above substrate as a first retardation layer using a thermosetting acrylic adhesive (Lintec) with a thickness of 5 μm, and 2 As a phase contrast layer, a λ/4 phase contrast layer (nematic liquid crystal layer) with a thickness of 1.0 μm was bonded using a UV-curable epoxy adhesive (Daikin, UV-1100) with a thickness of 2 μm. An adhesive layer 140 was bonded to the opposite side of the λ/4 phase difference layer on the viewing side. At this time, the adhesive layer 140 was formed by bonding the thermosetting acrylic adhesive sheet (A-1) of Preparation Example 2 to the opposite side of the viewing side of the λ/4 phase difference layer and peeling off the PET film.

Example 3: Production of polarizer

A polarizing plate was manufactured with the same structure as the embodiment of FIG. 1 according to the following method.

An acrylic film with a thickness of 20 μm was bonded to the viewing side of the polarizer prepared in Preparation Example 1 as a substrate using a water-based adhesive. At this time, thermosetting water-based PVA adhesive was used as the water-based adhesive. The water-based adhesive was cured by drying in an oven at 60°C for 5 minutes. Afterwards, a λ/2 retardation layer (discotic liquid crystal layer) with a thickness of 2.0 μm was bonded to the polarizer equipped with the above substrate as a first retardation layer using a thermosetting acrylic adhesive (Lintec) with a thickness of 5 μm, and 2 As a phase contrast layer, a λ/4 phase contrast layer (nematic liquid crystal layer) with a thickness of 1.0 μm was bonded using a UV-curable epoxy adhesive (Daikin, UV-1100) with a thickness of 2 μm. An adhesive layer 140 was bonded to the opposite side of the λ/4 phase difference layer on the viewing side. At this time, the adhesive layer 140 was formed by bonding the thermosetting acrylic adhesive sheet (A-4) of Preparation Example 5 to the opposite side of the viewing side of the λ/4 retardation layer and peeling off the PET film.

Comparative Example 1: Production of polarizer

A polarizing plate was manufactured with the same structure as the embodiment of FIG. 1 according to the following method.

An acrylic film with a thickness of 20 μm was bonded to the viewing side of the polarizer prepared in Preparation Example 1 as a substrate using a water-based adhesive. At this time, thermosetting water-based PVA adhesive was used as the water-based adhesive. The water-based adhesive was cured by drying in an oven at 60°C for 5 minutes. Afterwards, a λ/2 retardation layer (discotic liquid crystal layer) with a thickness of 2.0 μm was bonded to the polarizer equipped with the above substrate as a first retardation layer using a thermosetting acrylic adhesive (Lintec) with a thickness of 5 μm, and 2 As a phase contrast layer, a λ/4 phase contrast layer (nematic liquid crystal layer) with a thickness of 1.0 μm was bonded using a UV-curable epoxy adhesive (Daikin, UV-1100) with a thickness of 2 μm. An adhesive layer 140 was bonded to the opposite side of the λ/4 phase difference layer on the viewing side. At this time, the adhesive layer 140 was formed by bonding the thermosetting acrylic adhesive sheet (A-3) of Preparation Example 4 to the opposite side of the viewing side of the λ/4 phase difference layer and peeling off the PET film.

Comparative Example 2: Production of polarizer

A polarizing plate was manufactured with the same structure as the embodiment of FIG. 1 according to the following method.

An acrylic film with a thickness of 20 μm was bonded to the viewing side of the polarizer prepared in Preparation Example 1 as a substrate using a water-based adhesive. At this time, thermosetting water-based PVA adhesive was used as the water-based adhesive. The water-based adhesive was cured by drying in an oven at 60°C for 5 minutes. Afterwards, a λ/2 retardation layer (discotic liquid crystal layer) with a thickness of 2.0 μm was bonded to the polarizer equipped with the above substrate as a first retardation layer using a thermosetting acrylic adhesive (Lintec) with a thickness of 5 μm, and 2 As a phase contrast layer, a λ/4 phase contrast layer (nematic liquid crystal layer) with a thickness of 1.0 μm was bonded using a UV-curable epoxy adhesive (Daikin, UV-1100) with a thickness of 2 μm. An adhesive layer 140 was bonded to the opposite side of the λ/4 phase difference layer on the viewing side. At this time, the adhesive layer 140 was formed by bonding the thermosetting acrylic adhesive sheet (A-2) of Preparation Example 3 to the opposite side of the viewing side of the λ/4 phase difference layer and peeling off the PET film.

Comparative Example 3: Production of polarizer

A polarizing plate was manufactured with the same structure as the embodiment of FIG. 1 according to the following method.

A cycloolefin polymer film with a thickness of 18 μm was bonded to the viewing side of the polarizer prepared in Preparation Example 1 as a substrate using a water-based adhesive. At this time, thermosetting water-based PVA adhesive was used as the water-based adhesive. The water-based adhesive was cured by drying in an oven at 60°C for 5 minutes. Afterwards, a λ/2 retardation layer (discotic liquid crystal layer) with a thickness of 2.0 μm was bonded to the polarizer equipped with the above substrate as a first retardation layer using a thermosetting acrylic adhesive (Lintec) with a thickness of 5 μm, and 2 As a phase contrast layer, a λ/4 phase contrast layer (nematic liquid crystal layer) with a thickness of 1.0 μm was bonded using a UV-curable epoxy adhesive (Daikin, UV-1100) with a thickness of 2 μm. An adhesive layer 140 was bonded to the opposite side of the λ/4 phase difference layer on the viewing side. At this time, the adhesive layer 140 was formed by bonding the thermosetting acrylic adhesive sheet (A-1) of Preparation Example 2 to the opposite side of the viewing side of the λ/4 phase difference layer and peeling off the PET film.

Comparative Example 4: Production of polarizer

A polarizing plate was manufactured with the same structure as the embodiment of FIG. 1 according to the following method.

A cycloolefin polymer film with a thickness of 18 μm was bonded to the viewing side of the polarizer prepared in Preparation Example 1 as a substrate using a water-based adhesive. At this time, thermosetting water-based PVA adhesive was used as the water-based adhesive. The water-based adhesive was cured by drying in an oven at 60°C for 5 minutes. Afterwards, a λ/2 retardation layer (discotic liquid crystal layer) with a thickness of 2.0 μm was bonded to the polarizer equipped with the above substrate as a first retardation layer using a thermosetting acrylic adhesive (Lintec) with a thickness of 5 μm, and 2 As a phase contrast layer, a λ/4 phase contrast layer (nematic liquid crystal layer) with a thickness of 1.0 μm was bonded using a UV-curable epoxy adhesive (Daikin, UV-1100) with a thickness of 2 μm. An adhesive layer 140 was bonded to the opposite side of the λ/4 phase difference layer on the viewing side. At this time, the adhesive layer 140 was formed by bonding the thermosetting acrylic adhesive sheet (A-2) of Preparation Example 3 to the opposite side of the viewing side of the λ/4 phase difference layer and peeling off the PET film.

Experiment example:

The physical properties of the polarizing plates manufactured in the examples and comparative examples were measured by the following method, and the results are shown in Tables 1 to 3 below.

(1) Elastic recovery rate

The elastic recovery rate (%) of the polarizing plates manufactured in the examples and comparative examples was measured, and the results are shown in Tables 1 and 2 below.

Specifically, the elastic recovery rate (%) when a load of 10 mN was applied to the substrate surface of the polarizing plate for 20 seconds with an indenter in the form of a triangular pyramid tip (Vickers tip) was measured using a nano indenter.

(2) Shock absorption amount

The shock absorption (gf·s) of the polarizers manufactured in the examples and comparative examples was measured, and the results are shown in Tables 1 and 2 below.

Specifically, a pen with a tip diameter of 1 mm and a weight of 5 g was dropped from a height of 50 mm on the substrate surface of the polarizer, and the impact absorption (gf·s) was measured using an impact tester (PP Tester, SurTA system). was measured.

Using the elastic recovery rate (%) value as A and the shock absorption (gf·s) value as B, the A/B value was obtained and shown in Tables 1 and 2 below.

(3) Martens hardness (HM)

The Martens hardness (MPa) of the polarizing plates manufactured in the above Examples and Comparative Examples and the substrate used here were measured using a nano indenter, and the results are shown in Tables 1 and 2 below.

Specifically, the Martens hardness (MPa) when a load of 10 mN was applied for 20 seconds with an indenter in the form of a triangular pyramid tip (Vickers tip) on the substrate surface of the polarizer or the surface of the substrate before manufacturing the polarizer. Measurements were made using a nano indenter.

(4) Storage modulus (G')

The storage elastic modulus (G') of the adhesive layer 140 used in the examples and comparative examples was measured by the following method, and the results are shown in Table 3 below.

Specifically, the thermosetting acrylic adhesive used in the adhesive layer formed on the opposite side of the viewing side of the λ/4 retardation layer was produced in the form of a film with a thickness of 800 ㎛, and then measured with a rheometer (MCR-301, Anton Paar). The storage modulus (G') was measured at a frequency of 1 Hz and a strain of 1% under the conditions of -25℃ to 85℃ (5℃/min) using PP08 (8mm diameter).

(5) Impact resistance

The impact resistance of the polarizing plates manufactured in the above examples and comparative examples was evaluated, and the results are shown in Tables 1 and 2 below.

Specifically, the depth (㎛) and size (㎛) of the crack that occurred when a pen with a tip diameter of 1 mm and a weight of 5 g was dropped from a height of 50 mm on the substrate surface of the polarizer were measured in 3D. Measurements were made using a microscope, and visibility was observed with a foreign matter inspection device.

<Evaluation criteria>

○: Polarizer cracks are recognized

×: Polarizer cracks are not recognized

(6) bending resistance

The bending resistance of the polarizing plates manufactured in the above Examples and Comparative Examples was evaluated, and the results are shown in Tables 1 and 2 below.

Specifically, a sample of 20 mm Appearance defects such as discoloration were confirmed.

(7) Cutting processability

The cutting processability of the polarizing plates manufactured in the above Examples and Comparative Examples was evaluated as follows, and the results are shown in Tables 1 and 2 below.

Specifically, the polarizing plate was cut using a cutting machine (TMC-600, TOKO), and the cutting processability was evaluated according to the following evaluation criteria.

<Evaluation criteria>

OK: When cutting with a cutter, the sample does not stick to the knife.

NG: When cutting with a cutter, the sample adheres to the knife.

Example 1 Example 2 Example 3 Polarizer configuration write ACRYL (20㎛) ACRYL (18㎛) ACRYL (20㎛) 　G'(MPa) (@25℃) of adhesive layer 140 0.070 0.070 0.046 Thickness of the adhesive layer 140 50㎛ 50㎛ 25㎛ folding tester 85℃ / 1.5R In-folding 200,000 times OK 200,000 times OK 200,000 times OK 200,000 times No cracks or discoloration No cracks or discoloration No cracks or discoloration Impact resistance (whether or not there are cracks) X X X 3D microscope crack depth (㎛) 46 51 47 crack size (㎛) 270 410 290 nano indenter HM (MPa) write 225 202 225 polarizer 36.7 32.5 31.2 Elastic recovery rate (A) (%) 72.7 73.2 73 impact tester Shock absorption (B) (gf·s) 0.11 0.12 0.10 A/B 661 610 730 Cutting processability OK OK OK

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Polarizer configuration write ACRYL (20㎛) ACRYL (20㎛) COP (18㎛) COP (18㎛) G'(MPa) (@25℃) of adhesive layer 140 0.046 0.074 0.070 0.074 Thickness of adhesive layer 140 50㎛ 50㎛ 50㎛ 50㎛ folding tester 85℃ / 1.5R In-folding 200,000 times OK 130,000 times NG 200,000 times OK 130,000 times NG 200,000 times No cracks or discoloration crack occurs No cracks or discoloration crack occurs Impact resistance (whether or not there are cracks) X O O O 3D microscope crack depth (㎛) 40 52 52 60 crack size (㎛) 205 450 630 710 nano indenter HM (MPa) write 225 225 145 145 polarizer 28.5 37.2 26.9 28.4 Elastic recovery rate (A) (%) 73.7 71.2 72.5 71 impact tester Shock absorption (B) (gf·s) 0.10 0.12 0.12 0.13 A/B 737 593 604 546 Cutting processability NG OK OK OK

G' (MPa) -20℃ 25℃ 85℃ Production example 2 0.129 0.070 0.044 Production example 3 0.132 0.074 0.050 Production example 4 0.086 0.046 0.024

Through Tables 1 and 2, according to an embodiment of the present invention, the polarizer of the example having an A/B value of 610 to 730 has a thin film structure using a liquid crystal compound in the retardation layer and has excellent impact resistance, so it is resistant to external shocks. While the occurrence of cracks in the polarizing plate can be suppressed and at the same time has good cutting processability, it can be confirmed that the polarizing plate of the comparative example whose A/B value is outside the above range is poor in at least one of impact resistance and cutting processability.

As the specific parts of the present invention have been described in detail above, it is clear to those skilled in the art that these specific techniques are merely preferred embodiments and do not limit the scope of the present invention. do. Anyone skilled in the art to which the present invention pertains will be able to make various applications and modifications within the scope of the present invention based on the above contents.

Accordingly, the actual scope of the present invention will be defined by the appended claims and their equivalents.

10: OLED panel 20: Transparent adhesive layer
30: cover window 100: polarizer
110: substrate 120: polarizer
130: Coated retardation layer 140: Adhesive layer

Claims (10)

A polarizing plate in which a substrate, a polarizer, a coated retardation layer, and an adhesive layer are sequentially laminated, and satisfies the following equation 1:
[Equation 1]
610 ≤ A/B ≤ 730
In the above equation,
A is the elastic recovery rate (%) measured using a nano indenter when a load of 10 mN is applied to the polarizer for 20 seconds,
B is the shock absorption (gf·s) measured using an impact tester when a pen with a tip diameter of 1 mm and a weight of 5 g is dropped from a height of 50 mm on a polarizing plate. The polarizing plate of claim 1, wherein the substrate is an acrylic substrate and has a thickness of 15 to 25㎛. The polarizing plate of claim 1, wherein the Martens hardness of the substrate is 160 to 250 MPa when measured using a nano indenter by applying a load of 10 mN. The polarizing plate of claim 1, wherein the coated retardation layer includes a λ/4 retardation layer. The method of claim 4, wherein the coated phase difference layer is a λ/4 phase difference layer, a phase difference layer in which a λ/2 phase difference layer and a λ/4 phase difference layer are sequentially stacked from the viewer side, or a λ/4 phase difference layer from the viewer side. A polarizer in which a layer and a positive C plate layer are sequentially laminated. The polarizing plate of claim 1, wherein the adhesive layer is formed from a thermosetting acrylic adhesive composition and has a thickness of 20 to 100 ㎛. The polarizing plate of claim 1, wherein the storage modulus (G') of the adhesive layer is 0.070 MPa or less at 25°C. The polarizing plate of claim 1, wherein the Martens hardness of the polarizing plate is 30 to 37 MPa when measured using a nano indenter by applying a load of 10 mN. The polarizer according to claim 1, which is for flexible use. An image display device comprising the polarizing plate according to any one of claims 1 to 9.