WO2020005041A1 - Polarizing plate, liquid crystal panel, and display device - Google Patents

Abstract

The present invention relates to a polarizing plate comprising: a polarizer; a hard coating layer formed on one side of the polarizer and having a thickness of 10um or less; and an optical laminate formed on the other side of the polarizer and including a light-transmissive substrate.

Description

Polarizers, Liquid Crystal Panels and Display Devices

Cross Citation with Related Application (s)

The present application is filed with Korean Patent Application No. 10-2018-0075899 dated June 29, 2018, Korean Patent Application No. 10-2018-0167778 dated December 21, 2018, and Korean Patent Application No. 10-2019 dated June 28, 2019. Claiming the benefit of priority based on -0078374, all contents disclosed in the literature of the corresponding Korean patent applications are incorporated as part of this specification.

The present invention relates to a polarizing plate, a liquid crystal panel and a display device.

The liquid crystal display is a display that visualizes the polarization due to the switching effect of the liquid crystal, and is used in various categories ranging from large-sized TVs as well as small and medium-sized displays such as computers, laptops, electronic watches, and portable terminals.

A large number of polarizing plates currently in mass production for display devices are dyed polyvinyl alcohol films with dichroic substances such as iodine or dichroic dyes, crosslinked with boron compounds, and then stretched and oriented to form polarizing films (polarizers). What bonded together the protective film which is optically transparent and mechanical strength on both surfaces or one side is used.

However, the stretched polyvinyl alcohol-based film has a problem that shrinkage deformation easily occurs under durability conditions such as high temperature and high humidity. When the polarizer is deformed, the stress affects the protective film and the liquid crystal cell, resulting in warpage. As a result, problems such as a change in physical properties of the polarizing plate including the same and a light leakage phenomenon in the liquid crystal display may occur.

The present invention is to provide a polarizing plate which can prevent cracks by implementing a stable internal structure while controlling the thermal contraction rate of the detailed constituent layer, etc. and having a good bending balance, and can prevent light leakage phenomenon of the liquid crystal display device. It is for.

Moreover, this invention is providing the liquid crystal panel and display apparatus which contain the said polarizing plate, respectively.

In the present specification, a polarizer; A hard coating layer having a thickness of 10 μm or less formed on one surface side of the polarizer; And an optical laminate including a light transmissive substrate formed on the other side of the polarizer.

In addition, in this specification, a polarizer; A hard coating layer having a thickness of 10 μm or less formed on one surface side of the polarizer; And an optical laminate including a light-transmissive substrate formed on the other side of the polarizer; and a second of the optical laminate perpendicular to the first direction with respect to the heat shrinkage strain value in the first direction of the optical laminate. The polarizing plate containing is provided with the ratio of the heat shrink deformation value of a specific range being a specific range.

In addition, in this specification, a polarizer; A hard coating layer having a thickness of 10 μm or less formed on one surface side of the polarizer; And an optical laminate including a light transmissive substrate formed on the other surface side of the polarizer, wherein the optical laminate is perpendicular to the first direction with respect to the heat shrinkage strain value in the first direction of the optical laminate. A polarizing plate having a ratio of heat shrinkage strain values in two directions of 0.8 to 1.2 is provided.

In addition, in the present specification, a liquid crystal panel in which the polarizing plate is formed on at least one surface of a liquid crystal cell is provided.

In addition, in the present specification, a display device including the polarizing plate is provided.

Hereinafter, a polarizing plate, a liquid crystal panel, and a display device according to specific embodiments of the present invention will be described in more detail.

In the present invention, terms such as first and second are used to describe various components, which terms are used only for the purpose of distinguishing one component from other components.

In addition, (meth) acryl [(meth) acryl] is meant to include both acryl and methacryl.

In addition, the inorganic nanoparticles of the hollow structure refers to particles having a form in which an empty space exists on the surface and / or inside of the inorganic nanoparticles.

In addition, (co) polymer is meant to include both co-polymers and homo-polymers.

According to one embodiment of the invention, a polarizer; A hard coating layer having a thickness of 10 μm or less formed on one surface side of the polarizer; And an optical laminate including a light transmissive substrate formed on the other side of the polarizer, wherein the optical laminate is perpendicular to the first direction with respect to the heat shrinkage strain value in the first direction of the optical laminate. A polarizing plate may be provided in which the ratio of the heat shrinkage strain values in the two directions is 0.8 to 1.2.

Triacetyl cellulose (TAC) film, which is widely used as a polarizer protective film of a polarizing plate, is weak in water resistance and may be distorted in a high temperature / high humidity environment and causes defects such as light leakage. As a result of using the light-transmitting substrate having, the experiment confirmed that durability can be secured without a great change in physical properties or form even after long-term exposure under high temperature and high humidity conditions.

The polarizing plate of the embodiment has a ratio (R) of the heat shrinkage strain value in the second direction of the optical laminate perpendicular to the first direction to the heat shrinkage strain value in the first direction of the optical laminate is 0.8 to 1.2, or 0.85. To 1.1, whereby the heat shrinkage rate or heat shrinkage strain between layers is controlled even when a temperature of 60 ° C. or higher is applied in the manufacturing process, and the warpage balance of the polarizer is also good. Cracks can be prevented and light leakage of the liquid crystal display can be prevented.

The ratio R may be defined by the following general formula (1).

[Formula 1]

Ratio (R) of the heat shrinkage strain value in the second direction of the optical laminate perpendicular to the first direction with respect to the heat shrinkage strain value in the first direction of the optical laminate

= Heat shrink deformation value in the second direction of the optical laminate / heat shrink deformation value in the first direction of the optical laminate

Each of the heat shrinkage strain values in the first direction of the optical laminate and the heat shrinkage strain values in the second direction of the optical laminate are 80 ° C. to 120 ° C. with an initial length in each of the first and second directions of the optical laminate. The difference in length measured after 80 to 120 hours of exposure to temperature. More specifically, it may be a difference between an initial length of the first and second directions of the optical laminate and a length measured after 96 hours of exposure to a temperature of 100 ° C.

The heat shrinkage strain value in the first direction of the optical laminate and the heat shrinkage strain value in the second direction of the optical laminate may be defined by the following general formulas (2) and (3).

[Formula 2]

Heat shrinkage strain value in the first direction of the optical laminate

= Initial length of the first direction of the optical laminate (MD direction of PET)-first direction of the optical laminate measured after 80 to 120 hours exposure to a temperature of 80 ° C to 120 ° C (MD direction of PET) ) Length

[Formula 3]

Heat shrinkage deformation value in the second direction of the optical laminate

= Initial length of the second direction (TD direction of the PET) of the optical laminate-second length (TD direction of the PET) of the optical laminate measured after 80 to 120 hours exposure to a temperature of 80 ℃ to 120 ℃

The optical laminate may have the largest deformation in a temperature range of about 80 ° C., specifically, in a temperature range of 80 ° C. to 120 ° C., and includes a light-transmitting substrate on one side of the polarizer and less than 10 μm on the other side. With the hard coating layer having a thickness, the ratio of the heat shrinkage strain value in the second direction of the optical laminate perpendicular to the first direction to the heat shrinkage strain value in the first direction of the optical laminate is 0.8 to 1.2, Or 0.85 to 1.1.

In particular, when the optically transparent substrate included in the optical laminate is a polymer film, for example, TAC, PET, acrylic resin, cycloolefin polymer (COP), polycarbonate, polymethyl methacrylate (PMMA) and the like, 80 The temperature-dependent change or heat shrinkage deformation may be greater than the previous temperature range in the temperature range of about ℃, the polarizing plate is the first confirmed after 80 to 120 hours exposure to a temperature of 80 ℃ to 120 ℃ The ratio of the heat shrinkage strain value in the second direction of the optical laminate perpendicular to the first direction to the heat shrinkage strain value in the direction may be 0.8 to 1.2, thereby realizing better durability against heat deformation or heat shrinkage, It is possible to obtain structural stability that is difficult to achieve in the polarizer of the other structure previously run.

In addition, the polarizing plate of the embodiment includes the optical laminate and at the same time, including a hard coating layer having a thickness of less than 10um formed on one side of the polarizer, while achieving a thinner thickness, the heat shrinkage and heat between the detailed layers The contracting force can be properly adjusted, and a solid internal structure can be realized.

In particular, the previously known polarizing plates have a structure in which a triacetyl cellulose (TAC) film or the like is positioned on both sides of the polarizer, whereas the polarizing plate of the embodiment has an optical stack having the above-described characteristics on one side and 10 μm on the other side. A hard coating layer having a thickness below may be positioned to block water transfer to the PVA film, and to lower the overall thickness of the polarizing film.

In this case, a first direction of the optical laminate may be an MD direction of the light transmissive substrate, and a second direction of the optical laminate may be a TD direction of the light transmissive substrate.

When the ratio of the heat shrinkage strain value in the second direction of the optical laminate perpendicular to the first direction to the heat shrinkage strain value in the first direction of the optical laminate is too small or large, the stress transfer at high temperature and high humidity is uneven. In this case, the adhesion between the sublayers may be lowered, the polarizer may be lifted between the optical stack, or cracks may be generated in the polarizer, and light leakage of the liquid crystal display may occur.

The light transmissive substrate may have a transmittance of 50% or more at a wavelength of 300 nm or more.

On the other hand, an example of the polarizing plate 100 of the embodiment is shown in FIG. The polarizer 100 shown in FIG. 1 includes a polarizer 20 and a hard coating layer 30 having a thickness of 10 μm or less positioned to face each other with the polarizer centered thereon and a light transmissive substrate 10.

Meanwhile, the light transmissive substrate may have a retardation (Rth) in the thickness direction measured at a wavelength of 400 nm to 800 nm of 3,000 nm or more.

By controlling the retardation of the light-transmitting substrate to 3,000 nm or more, 4,000 to 15,000 nm, or 5,000 to 10,000 nm, the rainbow phenomenon due to destructive interference is suppressed, and the visibility of the image display device is improved in accordance with the cellulose ester-based film. You can.

The retardation is a refractive index in the slow axis direction (n _x ) which is the direction of the largest refractive index in the plane of the light transmissive substrate, a refractive index (n _y ) in the fast axis direction which is a direction orthogonal to the slow axis direction, and the light transmittance The thickness d (unit: nm) of the substrate may be calculated by substituting the following Equation 1.

[Equation 1]

Re = (n _x -n _y ) * d

In addition, this retardation may be, for example, a value measured using an automatic birefringence meter (KOBRA-WR, measuring angle: 0 °, measuring wavelength: 548.2 nm). Alternatively, the retardation can also be obtained by the following method. First, two axial refractive indices (n _x , n _y ) which are provided in the alignment axis direction of the light-transmitting substrate using two polarizing plates and orthogonal to the orientation axis direction are made by an Abbe type refractive index meter (NAR-4T). Obtain At this time, the axis showing a larger refractive index is defined as the slow axis. In addition, the thickness of the light transmissive substrate is measured using an electric micrometer, for example, and the refractive index difference n _x -n _y (hereinafter, n _x -n _y is referred to as Δn) is calculated using the refractive index obtained above. And the retardation can be calculated | required by the product of this refractive index difference (DELTA) n and the thickness d (nm) of a transparent base material.

Since the retardation of the light transmissive substrate is 3000 nm or more, the refractive index difference Δn may be 0.05 or more, 0.05 to 0.20, or 0.08 to 0.13. When the refractive index difference Δn is less than 0.05, the thickness of the light transmissive substrate required to obtain the retardation value described above may be increased. On the other hand, when the refractive index difference Δn exceeds 0.20, it is necessary to excessively increase the draw ratio, so that the light-transmitting base material is easily torn and broken, and the practicality as an industrial material may be remarkably lowered, and the heat and moisture resistance is lowered. Can be.

The refractive index (n _x ) in the slow axis direction of the light transmissive substrate may be 1.60 to 1.80 or 1.65 to 1.75. Meanwhile, the refractive index n _y in the fast axis direction of the light transmissive substrate having the birefringence in the plane may be 1.50 to 1.70, or 1.55 to 1.65.

On the other hand, as the light-transmitting substrate is excellent in water resistance, there is little possibility of causing a light leakage phenomenon, it is possible to use a polyethylene terephthalate (PET) film excellent mechanical properties.

On the other hand, the light-transmitting substrate has a retardation (Rth) of the thickness direction measured at a wavelength of 400nm to 800nm while the 3,000nm or more It may have low water permeation characteristics. More specifically, the light transmissive substrate may be 100 g / m 2 or less, or 10 to 100 g / m 2 when the moisture permeation amount is measured for 24 hours at 40 ° C. and 100% humidity.

On the other hand, the thickness of the light transmissive substrate is not particularly limited, but may be 10 to 150㎛, 20 to 120㎛, or 30 to 100㎛. When the thickness of the light transmissive substrate is less than 10 μm, the thickness of the hard coating layer is too thin, so that warpage occurs, and the flexibility of the light transmissive substrate may be difficult to control the process. In addition, when the light transmissive substrate is excessively thick, the transmittance of the light transmissive substrate may decrease, resulting in a decrease in optical properties, and it is difficult to thin the image display apparatus including the same.

The ratio of the thickness of the hard coating layer to the thickness of the light transmissive substrate may be 0.02 to 0.25 in order to prevent the phenomenon that the internal structure of the polarizing plate is more robust and warpage occurs even when exposed to high temperature conditions.

As described above, if the thickness of the light transmissive substrate does not have a proper range compared to the thickness of the hard coating layer, warpage may occur in the polarizing plate, and the flexibility of the light transmissive substrate may be difficult to control the process.

On the other hand, the polarizing plate of the embodiment can implement a rigid structure even through a thinner thickness than other polarizing plate structures previously known, and can also have a characteristic that the durable structure or physical properties do not significantly change by external heat.

More specifically, the polarizer; The hard coating layer; And the light transmissive substrate; the combined thickness may be 200 μm or less. For example, the polarizer may have a thickness of 40 μm or less, or 1 to 40 μm, the hard coating layer may have a thickness of 10 μm or less, or 1 to 10 μm, and the light transmissive substrate may be 150 μm. It may have the following thickness.

On the other hand, the hard coating layer is not particularly limited in specific composition, for example, the hard coating layer is a binder resin; And inorganic fine particles dispersed in the binder resin and having organic particles having a particle size of 0.5 μm to 10 μm or having a particle size of 1 nm to 500 nm.

The binder resin included in the hard coating layer may include a photocurable resin. The photocurable resin refers to a polymer of a photopolymerizable compound that can cause a polymerization reaction when light such as ultraviolet rays is irradiated.

Examples of the photocurable resin include urethane acrylate oligomers, epoxide acrylate oligomers, reactive acrylate oligomer groups consisting of polyester acrylates and polyether acrylates; And dipentaerythritol hexaacrylate, dipentaerythritol pentaacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, glycerin propoxylate triacrylate, trimethylpropane ethoxylate triacrylate , A group consisting of a polyfunctional acrylate monomer composed of trimethylpropyl triacrylate, 1,6-hexanediol diacrylate, tripropylene glycol diacrylate and ethylene glycol diacrylate ; The epoxy resin containing the polymer or copolymer formed from these, and the epoxy group containing an epoxy group, an alicyclic epoxy group, a glycidyl group epoxy group, or an oxetane group, etc. are mentioned.

The binder resin may further include a (co) polymer (hereinafter, referred to as a high molecular weight (co) polymer) having a weight average molecular weight of 10,000 g / mol or more together with the photocurable resin described above. The high molecular weight (co) polymer is, for example, at least one polymer selected from the group consisting of cellulose polymers, acrylic polymers, styrene polymers, epoxide polymers, nylon polymers, urethane polymers and polyolefin polymers. It may include.

The organic or inorganic fine particles are not particularly limited in particle size, but for example, the organic fine particles may have a particle size of 1 to 10 μm, and the inorganic particles may have a particle size of 1 nm to 500 nm, or 1 nm to 300 nm. Can have

In addition, specific examples of the organic or inorganic fine particles included in the hard coating layer are not limited. For example, the organic or inorganic fine particles may be organic fine particles or silicon oxide composed of acrylic resin, styrene resin, epoxide resin, and nylon resin. It may be an inorganic fine particle consisting of titanium dioxide, indium oxide, tin oxide, zirconium oxide and zinc oxide.

The polarizing plate of the embodiment includes a polarizer.

The polarizer may use a film made of polyvinyl alcohol (PVA) including a polarizer well known in the art, for example, iodine or dichroic dye. In this case, the polarizer may be prepared by dyeing and stretching an iodine or a dichroic dye on a polyvinyl alcohol film, but a method of manufacturing the same is not particularly limited.

On the other hand, when the polarizer is a polyvinyl alcohol film, the polyvinyl alcohol film may be used without particular limitation as long as it contains a polyvinyl alcohol resin or a derivative thereof. In this case, examples of the derivative of the polyvinyl alcohol resin include, but are not limited to, polyvinyl formal resin, polyvinyl acetal resin, and the like. Alternatively, the polyvinyl alcohol film may be a commercially available polyvinyl alcohol film generally used in the manufacture of polarizers in the art, for example, P30, PE30, PE60 manufactured by Kureray, M3000, M6000 manufactured by Nippon Synthetic, and the like. have.

On the other hand, the polyvinyl alcohol film is not limited thereto, but the polymerization degree may be 1000 to 10000 or 1500 to 5000. When the degree of polymerization satisfies the above range, the molecular motion is free and can be mixed flexibly with iodine or dichroic dye. In addition, the polarizer may have a thickness of 40 μm or less, 30 μm or less, 20 μm or less, 1 to 20 μm, or 1 μm to 10 μm. In this case, thin weight reduction of devices, such as a polarizing plate and an image display apparatus containing the said polarizer, is possible.

On the other hand, the optical laminate may further include a second hard coating layer having a thickness of 1 to 100㎛ formed on one surface of the light transmissive substrate to face the polarizer.

As the second hard coating layer is formed, the optical laminate may implement a predetermined optical characteristic or functionality on one surface of the polarizing layer. For example, the second hard coating layer may serve as an antiglare layer, a high refractive index layer, a medium refractive layer, or a conventional hard coating layer.

Although a specific example of the second hard coating layer is not limited, the second hard coating layer may also be a binder resin such as "hard coating layer having a thickness of 10 μm or less formed on one side of the polarizer"; And inorganic fine particles dispersed in the binder resin and having organic particles having a particle size of 0.5 μm to 10 μm or having a particle size of 1 nm to 500 nm.

The optical laminate may further include a low refractive index layer having a refractive index of 1.20 to 1.60 in a wavelength region of 380 nm to 780 nm formed on the other surface of the second hard coating layer.

The polarizing plate may further include an antireflection film formed on one surface of the light transmissive substrate so as to face the polarizer.

Another example of the polarizing plate 100 of the above embodiment is shown in FIG. 2. The polarizing plate 100 shown in FIG. 2 includes a polarizer 20 and a hard coating layer 30 and a light transmissive substrate 10 having a thickness of 10 μm or less positioned to face each other with the polarizer as the center. It includes an antireflection film 40 formed on one surface of the (10).

The antireflection film may have an average reflectance of 2% or less in a wavelength range of 380 nm to 780 nm.

The anti-reflection film may include a hard coating layer having a thickness of 1 to 100 μm and a low refractive layer having a refractive index of 1.20 to 1.60 in a wavelength region of 380 nm to 780 nm.

Specific examples of the hard coating layer included in the anti-radiation film are not limited, but the hard coating layer included in the anti-radiation film may also be a binder such as "hard coating layer having a thickness of 10 μm or less positioned to face the polarizer." Suzy; And organic fine particles dispersed in the binder resin and having a particle size of 0.5 μm to 10 μm and / or inorganic fine particles having a particle size of 1 nm to 500 nm.

The binder resin and the organic fine particles having a particle size of 0.5 μm to 10 μm or the inorganic fine particles having a particle size of 1 nm to 500 nm include the above-mentioned contents included in the hard coat layer included in the anti-radiation film.

The low refractive index layer having a refractive index of 1.20 to 1.60 in the wavelength region of 380 nm to 780 nm may include a binder resin and organic fine particles or organic fine particles dispersed in the binder resin, and optionally include a fluorine-containing compound having a photoreactive functional group, and / Or a silicon compound having a photoreactive functional group.

The binder resin comprises a (co) polymer comprising a polyfunctional (meth) acrylate-based repeating unit, such repeating unit being, for example, trimethylolpropane triacrylate (TMPTA), trimethylolpropaneethoxy tri From polyfunctional (meth) acrylate type compounds, such as acrylate (TMPEOTA), glycerin propoxylated triacrylate (GPTA), pentaerythritol tetraacrylate (PETA), or dipentaerythritol hexaacrylate (DPHA) It may be derived.

The photoreactive functional group included in the fluorine-containing compound or silicon-based compound may include one or more functional groups selected from the group consisting of (meth) acrylate groups, epoxide groups, vinyl groups (Vinyl), and thiol groups (Thiol). .

The fluorine-containing compound including the photoreactive functional group may include: i) an aliphatic compound or an aliphatic ring compound in which one or more photoreactive functional groups are substituted and at least one fluorine is substituted for at least one carbon; ii) a heteroaliphatic compound or a heteroaliphatic ring compound substituted with one or more photoreactive functional groups, at least one hydrogen substituted with fluorine, and one or more carbons substituted with silicon; iii) at least one photoreactive functional group and a polydialkylsiloxane polymer substituted with at least one fluorine in at least one silicon; And iv) a polyether compound substituted with at least one photoreactive functional group and at least one hydrogen is substituted with fluorine.

The low refractive layer may include hollow inorganic nanoparticles, solid inorganic nanoparticles, and / or porous inorganic nanoparticles.

The hollow inorganic nanoparticles refer to particles having a maximum diameter of less than 200 nm and having a void space on the surface and / or inside thereof. The hollow inorganic nanoparticles may include one or more selected from the group consisting of inorganic fine particles having a number average particle diameter of 1 to 200 nm, or 10 to 100 nm. In addition, the hollow inorganic nanoparticles may have a density of 1.50 g / cm 3 to 3.50 g / cm 3.

The hollow inorganic nanoparticles may contain at least one reactive functional group selected from the group consisting of a (meth) acrylate group, an epoxide group, a vinyl group (Vinyl), and a thiol group (Thiol) on the surface. By containing the reactive functional group described above on the surface of the hollow inorganic nanoparticles, it may have a higher degree of crosslinking.

The solid inorganic nanoparticles may include at least one selected from the group consisting of solid inorganic fine particles having a number average particle diameter of 0.5 to 100 nm.

The porous inorganic nanoparticles may include one or more selected from the group consisting of inorganic fine particles having a number average particle diameter of 0.5 to 100nm.

The low reflection layer is 10 to 400 parts by weight of the inorganic nanoparticles relative to 100 parts by weight of the (co) polymer; And 20 to 300 parts by weight of a fluorine-containing compound and / or a silicon-based compound including the photoreactive functional group.

The polarizing plate may further include an adhesive layer disposed between the polarizer and the light transmissive substrate and having a thickness of 0.1 μm to 5 μm.

As the adhesive, various adhesives for polarizing plates used in the art, for example, polyvinyl alcohol-based adhesives, polyurethane-based adhesives, acrylic adhesives, cationic or radical adhesives, and the like may be used as the adhesive.

On the other hand, the polarizing plate may further include an adhesive layer formed on the other surface of the hard coating film in contact with the polarizer.

The adhesive layer may enable attachment of the polarizing plate of the embodiment and the image panel of the image display device. The adhesive layer may be formed using various adhesives well known in the art, and the kind thereof is not particularly limited. For example, the pressure-sensitive adhesive layer may be a rubber pressure sensitive adhesive, an acrylic pressure sensitive adhesive, a silicone pressure sensitive adhesive, a urethane pressure sensitive adhesive, a polyvinyl alcohol pressure sensitive adhesive, a polyvinylpyrrolidone pressure sensitive adhesive, a polyacrylamide pressure sensitive adhesive, a cellulose pressure sensitive adhesive, a vinyl alkyl ether pressure sensitive adhesive, or the like. It can be formed using.

Another example of the polarizing plate 100 of the above embodiment is shown in FIG. 3. The polarizer 100 shown in FIG. 3 includes a polarizer 20 and a hard coating layer 30 and a light transmissive substrate 10 having a thickness of 10 μm or less positioned to face each other with the polarizer as the center. An anti-reflection film 40 formed on one surface of the (10), and the adhesive layer 60 formed between the polarizer and the light transmissive substrate and the adhesive layer 60 formed on the other surface of the hard coating film in contact with the polarizer It includes.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, for example, may have a thickness of 1 to 50um.

According to another embodiment of the invention, a liquid crystal panel in which a polarizing plate is formed on at least one surface of the liquid crystal cell may be provided.

An example of the liquid crystal panel 200 of the above embodiment is illustrated in FIG. 4. The liquid crystal panel 200 illustrated in FIG. 4 has a structure in which the polarizer 100 is formed on one surface of the liquid crystal panel.

In addition, another example of the liquid crystal panel 200 of the above embodiment is illustrated in FIG. 5. The liquid crystal panel 200 shown in FIG. 5 has a structure in which the polarizer 100 is formed on both surfaces of the liquid crystal panel.

In the liquid crystal panel, polarizers of claim 1 may be formed on both surfaces of the liquid crystal cell, and the two polarizers may be formed on one surface different from the MD direction of the polarizer of the polarizer formed on one surface of the liquid crystal cell. The MD direction of the may be positioned to be perpendicular to each other.

According to another embodiment of the invention, a display device including the polarizing plate described above may be provided.

Specific examples of the display device are not limited, and may be, for example, a device such as a liquid crystal display, a plasma display device, or an organic light emitting diode device.

As one example, the display device includes a pair of polarizing plates facing each other; A thin film transistor, a color filter, and a liquid crystal cell sequentially stacked between the pair of polarizing plates; And a liquid crystal display device including a backlight unit.

In the display device, the anti-reflection film may be provided on the outermost surface of the observer side or the backlight side of the display panel.

In the display device including the anti-reflection film, the anti-reflection film may be positioned on one surface of the polarizing plate relatively far from the backlight unit among the pair of polarizing plates.

In another example, the display apparatus may include a display panel; And the polarizing plate disposed on at least one surface of the display panel.

The display device may be a liquid crystal display device including a liquid crystal panel and an optical laminate provided on both surfaces of the liquid crystal panel, wherein at least one of the polarizers includes a polarizer according to one embodiment of the present specification. It may be a polarizing plate. At this time, the type of liquid crystal panel included in the liquid crystal display device is not particularly limited, but, for example, twisted nematic (TN) type, super twisted nematic (STN) type, F (ferroelectic) type or PD (polymer dispersed) type A passive matrix panel such as; Active matrix panels such as two-terminal or three-terminal; All known panels, such as an In Plane Switching (IPS) panel and a Vertical Alignment (VA) panel, can be applied.

According to the present invention, a polarizing plate capable of preventing cracks by implementing a stable internal structure while controlling the thermal contraction rate of the detailed constituent layers and having a good bending balance, and the light leakage phenomenon of the liquid crystal display device and the A liquid crystal panel and display device including a polarizing plate can be provided.

Figure 1 shows an example of a polarizing plate of an embodiment of the invention.

2 shows another example of a polarizing plate of an embodiment of the invention.

Figure 3 shows another example of a polarizing plate of an embodiment of the invention.

4 shows an example of a liquid crystal panel of an embodiment of the invention.

5 shows another example of a liquid crystal panel of an embodiment of the invention.

Embodiments of the invention are described in more detail in the following examples. However, the following examples are merely to illustrate the invention, but the content of the present invention is not limited by the following examples.

[Production example]

Preparation Example 1 Preparation of Optical Laminate

(1) Preparation of Coating Liquid for Hard Coating Layer Formation

The components shown in Table 1 were mixed and mixed to prepare hard coat layer-forming coating liquids (B1, B2) of the optical laminate.

TMPTA: Trimethylolpropane triacrylate

PETA: pentaerythritol triacrylate

UA-306T: reactant of toluene diisocyanate with pentaerythritol triacrylate with urethane acrylate (Kyoeisha)

SC2152: A compound in which hexamethylene diisocyanurate (HMDI) and an acrylate compound are connected by a urethane bond [mass average molecular weight 20,000 / manufacturer: Miwon Chemical]

IRG-184: initiator (Irgacure 184, Ciba)

Tego wet 270: tego leveling agent

BYK 350: BYK's Leveling Agent

2-butanol Butyl Alcohol

IPA Isopropyl Alcohol

XX-103BQ (2.0 μm 1.515): Copolymerized particles of polystyrene and polymethyl methacrylate (manufactured by Sekisui Plastic)

XX-113BQ (2.0 μm 1.555): Copolymerized particles of polystyrene and polymethyl methacrylate (manufactured by Sekisui Plastic)

MA-ST (30% in MeOH): A dispersion in which nanosilica particles of size 10-15 nm are dispersed in methyl alcohol (product of Nissan Chemical)

(2) Preparation of Coating Liquid (C) for Forming Low Reflective Layer

100 g of trimethylolpropane triacrylate (TMPTA), hollow silica nanoparticles (diameter range: about 42 nm to 66 nm, manufactured by JSC catalyst and chemicals) 283 g, solid silica nano particles (diameter range: about 12 nm to 19 nm) 59 g, 1st fluorine-containing compound (X-71-1203M, ShinEtsu) 115g, 2nd fluorine-containing compound (RS-537, DIC) 15.5g, and initiator (Irgacure 127, Ciba) 10g, MIBK To prepare a coating solution for forming a low reflection layer by diluting to a solid content concentration of 3% by weight in a (methyl isobutyl ketone) solvent.

(2) Production of Optical Laminate with Hard Coating Layer on Light-Transmitting Substrate

1) Measurement of the rate of heat shrinkage

Heat shrinkage ratio in the MD direction of the polyethylene terephthalate (PET) film used in each of the Examples and Comparative Examples: The ratio of the heat shrinkage rate in the TD direction is cut to each PET film to a size of 10cm * 10cm (width * length) 30 to 80 ℃ After leaving for a minute, the heat shrinkage (modified length / initial length) was calculated for each of the MD and TD directions.

PET 1: The heat shrink ratio (MD / TD) is about 1

PET 2: The heat shrink ratio (MD / TD) is about 0.5

2) Preparation of Optical Laminate

After coating each of the prepared coating liquid (B1, B2) for forming the hard coating layer (B1, B2) on each polyethylene terephthalate (PET) film shown in Tables 2 and 3 after the # 12 mayer bar and the temperature shown in Tables 2 and 3 Dried for 2 minutes and UV-cured to form a hard coat layer (coating thickness of 5 mu m). UV lamp was used for H bulb and curing reaction under nitrogen atmosphere. The amount of UV light irradiated during curing is 150 mJ / cm 2.

On the hard coat film, the coating liquid (C) for forming the low reflection layer was coated with a # 4 mayer bar so that the thickness was about 110 to 120 nm, and dried and cured at a temperature described in Tables 2 and 3 for 1 minute. . At the time of curing, the dried coating was irradiated with ultraviolet rays of 252 mJ / cm 2 under nitrogen purge.

2) Measurement of the heat shrinkage strain value of the optical laminate

The optical laminate was cut at 12 cm in the MD direction and the TD direction of the polyethylene terephthalate (PET) film, respectively, to obtain a heat shrinkage strain measurement sample. Prepared.

After leaving the prepared sample at a temperature of 100 ° C. for 96 hours, the length of each of the MD direction and the TD direction was measured to measure the heat shrinkage strain value in each direction.

[Formula 2-1]

Heat shrinkage deformation value in the first direction (MD direction of PET) of the optical laminate

= Initial length of the first direction of the optical laminate (MD direction of PET)-length of the first direction of the optical laminate (MD direction of PET) measured after exposure to a temperature of 100 ° C. for 96 hours

[Formula 3-1]

Thermal contraction deformation in a second direction (TD direction of PET) of the optical laminate

= Initial length of the second direction (TD direction of PET) of the optical laminate-length of the second direction (TD direction of PET) measured after 96 hours exposure to a temperature of 100 ° C

Then, the ratio (R) of the heat shrinkage deformation value in the second direction (TD direction of PET) of the optical laminate to the heat shrinkage deformation value of the first direction (MD direction of PET) of the optical laminate in the optical laminate. It was.

[General Formula 1-1]

Ratio (R) = heat shrink deformation value in the second direction (TD direction of PET) of the optical laminate / heat shrink deformation value in the first direction (MD direction of the PET) of the optical laminate

Preparation Example 2 Preparation of Coating Solution for Hard Coating Layer Formation and Preparation of Polarizer with Hard Coating Layer

(1) Preparation of Coating Liquid (A) for Forming Hard Coating Layer

Hard coating composition was prepared by uniformly mixing 28 g of trimethylloylpropane triacrylate, 2 g of KBE-403, initiator KIP-100f, 0.1 g, and 0.06 g of leveling agent (Tego wet 270).

[Examples and Comparative Examples: Production of Polarizing Plate and Liquid Crystal Panel]

(1) Preparation of Polarizing Plate

After bonding a polyvinyl alcohol polarizer (thickness: 25um, manufacturer: LG Chem) using a UV adhesive to the light transmissive substrate side of the optical laminate prepared in Preparation Example 1, the preparation on the opposite side of the light transmissive substrate The coating liquid (A) for forming a hard coating layer was applied to a thickness of 7 μm, and a hard coating layer was formed by irradiating 500 mJ / cm 2 ultraviolet rays to the coating dried under nitrogen purge.

(2) Sample Preparation for Thermal Shock Evaluation

The polarizing plate cut into a square having a length of 10 cm on one side is bonded to one surface of a glass for TV (12 cm wide, 12 cm long and 0.7 mm thick) using an adhesive to prepare a sample for thermal shock evaluation. At this time, the polarizing plate is cut so that the MD direction of the polarizer is parallel to one side of the square.

Experimental Example: Thermal Shock Evaluation

The thermal shock test was carried out under the following conditions with respect to the evaluation sample to which the prepared polarizing plate and the polarizing plate were bonded, and measured and confirmed the following three matters.

- Measuring conditions:

The polarizer and the evaluation sample are placed upright in the thermal shock chamber. The temperature was raised to 80 ° C. at room temperature and left for 30 minutes. After that, the temperature was lowered to −30 ° C. and the temperature was adjusted to room temperature after 30 minutes.

(1) Crack occurrence water

Cracks generated between the polarizers and the polarizers of the evaluation sample were visually confirmed to determine the number of cracks having a length of 1 cm or more.

(2) bubble

The bubbles generated between the polarizer and the protective film of the evaluation sample and the bubbles generated between the polarizer and the hard coating layer were visually confirmed to confirm the number of bubbles having a diameter of 5 mm or more.

(3) Vertex Lift (mm), 10x10 / film

Observe the four vertices of the polarizing plate sample to observe the lifting between the coating layer and the polarizer, the peeling between the polarizer and the protective film, the peeling and warping between the hard coating and the adhesive layer. When the lifting occurred and the warpage appeared, the average was measured by measuring the height of the bend from the bottom in a flat state.

As shown in Table 1 and Table 2, in the polarizing plate of the embodiment, even when a temperature of 60 ° C. or more is applied, the thermal contraction rate or thermal contraction strain value between the detailed layers is controlled, in particular, in the first direction of the optical laminate. It was confirmed that the ratio of the heat shrinkage strain value in the second direction of the optical laminate perpendicular to the first direction to the heat shrinkage strain value was within 0.8 to 1.2. Accordingly, it was confirmed that the bending balance of the polarizing plates of the above embodiments was also good, and it was possible to prevent cracking of the polarizing plate and to prevent light leakage from the liquid crystal display.

[Description of the code]

10 Light transmissive substrate

20 polarizer

30 hard coating layers

40 anti-reflection film

50 adhesive layer

60 adhesive layer

70 Liquid Crystal Cell

100 polarizer

200 liquid crystal panel

Claims (14)

1. Polarizer;

   A hard coating layer having a thickness of 10 μm or less formed on one surface side of the polarizer; And

   And an optical laminate including a light transmissive substrate formed on the other side of the polarizer.

   The ratio of the heat shrinkage strain value in the second direction of the optical laminate perpendicular to the first direction to the heat shrinkage strain value in the first direction of the optical laminate is 0.8 to 1.2,

   Polarizer.
2. The method of claim 1,

   Each of the heat shrinkage strain values in the first direction of the optical laminate and the heat shrinkage strain values in the second direction of the optical laminate is 80 ° C to 120 ° C relative to the initial length of each of the first and second directions of the optical stack. A polarizer, which is the difference in length values measured after 80 to 120 hours exposure to temperature.
3. The method according to claim 1 or 2,

   The first direction of the optical laminate is an MD direction of the light transmissive substrate (Machine Direction),

   The 2nd direction of the said optical laminated body is a TD direction (Transverse Direction) of the said light transmissive base material, The polarizing plate.
4. The method of claim 1,

   The said transparent substrate is a polarizing plate whose retardation (Rth) of the thickness direction measured by the wavelength of 400 nm-800 nm is 3,000 nm or more.
5. The method of claim 1,

   A polarizing plate, wherein the moisture permeation amount of the light transmissive substrate measured for 24 hours at 40 ° C. and 100% humidity condition is 100 g / m 2 or less.
6. The method of claim 1,

   The ratio of the thickness of the hard coat layer to the thickness of the light transmissive substrate is 0.02 to 0.25, the polarizing plate.
7. The method of claim 1,

   The polarizer; The hard coating layer; And the light-transmitting substrate; the polarizing plate having a thickness of 200 μm or less.
8. The method of claim 1,

   The hard coating layer is a binder resin; And organic fine particles dispersed in the binder resin and having an organic fine particle having a particle size of 0.5 μm to 10 μm or an inorganic fine particle having a particle size of 1 nm to 500 nm.
9. The method of claim 1,

   The optical laminate further comprises a second hard coating layer having a thickness of 1 to 100 μm formed on one surface of the light transmissive substrate so as to face the polarizer.
10. The method of claim 9,

    The optical laminate further comprises a low refractive index layer having a refractive index of 1.20 to 1.60 in a wavelength range of 380 nm to 780 nm formed on the other surface of the second hard coating layer.
11. The method of claim 1,

    And a adhesive layer disposed between the polarizer and the light transmissive substrate and having a thickness of 0.1 μm to 5 μm.
12. The liquid crystal panel of claim 1, wherein the polarizing plate is formed on at least one surface of the liquid crystal cell.
13. The method of claim 12,

    The polarizing plates of claim 1 are formed on both sides of the liquid crystal cell,

    The two polarizing plates are positioned such that the MD direction of the polarizer of the polarizing plate formed on one side of the liquid crystal cell and the MD direction of the polarizer of the polarizing plate formed on the other side are perpendicular to each other.
14. Display device comprising the polarizing plate of claim 1.

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