TWI599806B - Adhesive film for polarizing plate, polarizing plate including the same and optical display including the same - Google Patents

Description

Adhesive film for polarizing plate, polarizing plate including adhesive film, and optical display including polarizing plate

Korean Patent Application No. 10-2014-0145536 filed on October 24, 2014 in Korea Intellectual Property Office and Korean Patent Application No. 10-2015-0146947 filed on October 21, 2015 in Korea Intellectual Property Office The entire disclosure of the patent application is hereby incorporated by reference.

The present invention relates to an adhesive film for a polarizing plate, a polarizing plate including the adhesive film, and an optical display including the polarizing plate.

The liquid crystal display includes a panel for a liquid crystal display, the panel including a liquid crystal and a polarizing plate bonded to the panel via an adhesive layer. The polarizing plate has a multilayer structure including a polarizer and a protective film formed on the polarizer.

Since the polarizer and the protective film are formed of materials having different molecular structures and compositions, the polarizer and the protective film have different physical properties. In addition, the polarizer is stretched to have a unidirectional molecular arrangement to exhibit polarized light. Therefore, the size of the polarizing plate may vary due to shrinkage or expansion of the polarizer at high temperature and/or high humidity. Specifically, when the polarizing plate is fixed to the panel via the adhesive, stress generated by shrinkage or expansion of the polarizing plate is concentrated on the protective film at a high temperature and/or high humidity, so that Birefringence occurs on the protective film, thereby causing light leakage.

Light leakage can be suppressed by adjusting the stress on the adhesive layer to prevent residual stress from remaining in the protective film. However, since the protective film has residual stress at high temperature and/or high humidity, the crosslinked polymer in the adhesive film is aligned in a specific direction to cause birefringence. In general, acrylic adhesives exhibit negative birefringence.

A method of reducing stress by reducing the storage modulus of an adhesive film for a polarizing plate can be used to suppress light leakage. However, although the method is effective for displays of 7 inches or less, the adhesive is extremely flexible, and thus may have durability problems due to long-term use or stress caused by high temperature and high humidity (such as drums) Foaming or detachment) and may cause deterioration in workability, such as leakage of adhesive. Alternatively, there is a method of reducing a retardation change of a protective film at a high temperature and a high humidity, which is performed by suppressing stress by increasing a storage modulus of an adhesive film for a polarizing plate. However, although light leakage can be suppressed in the central portion of the display screen, since the stress increases as the distance from the center of the screen to the end increases, severe light leakage may occur at the end portion or the tip end of the screen.

In the related art, Korean Patent Publication No. 2009-0112916 A discloses an acrylic adhesive composition comprising an acrylic copolymer and a liquid containing a mesogen core in its structure. An optically anisotropic compound, and thus the negative birefringence of the adhesive layer due to residual stress can be adjusted to positive birefringence while ensuring excellent stress relaxation.

Thus, when a stress relieving adhesive having positive birefringence is used, the light leakage can be effectively suppressed at the end portion of the screen (here, the retardation of the protective film under high temperature/high humidity conditions is large). However, in this case, there is a problem that the light leakage in the center portion of the screen (here, the protective film has almost no delay variation) is inversely increased.

According to an aspect of the invention, an adhesive film for a polarizing plate may have a K value of 0.2 to 0.5 as calculated by the following Equation 1: <Equation 1> K = ∆G' × ∆R ₀ where ∆G' It is defined by Equation 2 and ∆R ₀ is defined by Equation 3. <Equation 2>∆G' = G1 - G2 where G1 is the storage modulus at 23 ° C (unit: MPa) and G2 is the storage modulus at 85 ° C (unit: MPa), as passed in The temperature was increased from 0 ° C to 100 ° C at a rate of 10 ° C / min, using a high-grade rheology measurement expansion system at a strain of 5%, a normal force of 100 Newtons, and an angular frequency of 1 rad/sec. (Advanced rheometry expansion system, ARES, TA Instrument Inc.) was subjected to a temperature scan test to measure the adhesion of a 500 micron thick adhesive film for a polarizing plate. <Equation 3> ∆R ₀ = R ₀₁ - R ₀₂ wherein R ₀₁ is a retardation (unit: nanometer) at a wavelength of 590 nm at 85 ° C and R ₀₂ is a retardation at a wavelength of 590 nm at 23 ° C ( Unit: nanometer), for example, when the temperature is raised from 0 ° C to 100 ° C at a rate of 10 ° C / min, when applying a stress of 125 mN / 15 mm to a 1 mm thick adhesive film for a polarizing plate measured.

In one embodiment, the adhesive film may have a G1 of 0.45 MPa to 1 MPa.

In one embodiment, the adhesive film may have a G2 of 0.01 MPa to 0.3 MPa.

In one embodiment, the adhesive film may be formed of an adhesive composition for a polarizing plate, the adhesive composition comprising (A) a crosslinkable (meth)acrylic copolymer containing a crosslinkable functional group (B) a non-crosslinkable (meth)acrylic copolymer having positive birefringence and (C) a curing agent.

In one embodiment, the (A) crosslinkable (meth)acrylic copolymer may be a copolymer of a monomer mixture comprising a monomer having a crosslinkable functional group, and in one embodiment, The monomer having a crosslinkable functional group may be present in the monomer mixture in an amount of from 1% by weight (% by weight) to 20% by weight.

In one embodiment, the (B) non-crosslinkable (meth)acrylic copolymer is a copolymer of a monomer mixture comprising a monomer having a crosslinkable functional group, and the crosslinkable functional group is contained The monomer of the group may optionally be present in the monomer mixture in an amount of less than 1% by weight.

In one embodiment, the weight average molecular weight of each of the (A) crosslinkable (meth)acrylic copolymer and the (B) non-crosslinkable (meth)acrylic copolymer may be Less than 1,000,000 g/mole.

In one embodiment, the (B) non-crosslinkable (meth)acrylic copolymer may have a weight average molecular weight of from 300,000 g/mol to less than 1,000,000 g/mole.

In one embodiment, the (A) crosslinkable (meth)acrylic copolymer is a copolymer comprising a monomer mixture of a hydroxyl group-containing (meth)acrylic monomer and a carboxylic acid group-containing At least one of (meth)acrylic monomers; and an alkyl group-containing (meth)acrylic monomer.

In one embodiment, the (B) non-crosslinkable (meth)acrylic copolymer is a copolymer comprising a monomer mixture of an aromatic group-containing (meth)acrylic monomer, an alkane-containing a (meth)acrylic monomer and a (meth)acrylic monomer represented by Formula 2: <Formula 2> Wherein A is a C ₁ to C ₂₀ aliphatic hydrocarbon group; B is -O- or -S-; R ₁ is hydrogen or a methyl group; R ₂ is a C ₁ to C ₂₀ aliphatic hydrocarbon group; and n is an integer of 1 to 5 .

In one embodiment, the (meth)acrylic monomer represented by Formula 2 may comprise 2-(2-ethoxyethoxy)ethyl (meth)acrylate.

In one embodiment, based on 100 parts by weight of the (A) crosslinkable (meth)acrylic copolymer and the (B) non-crosslinkable (meth)acrylic copolymer, A) the crosslinkable (meth)acrylic copolymer may be present in an amount of from 60 parts by weight to 95 parts by weight, and the (B) non-crosslinkable (meth)acrylic copolymer may be from 5 parts by weight to 40 parts by weight. The amount of serving exists.

In one embodiment, the adhesive composition for a polarizing plate may further comprise a decane coupling agent.

According to another aspect of the invention, a polarizing plate may comprise an adhesive film for a polarizing plate as set forth above.

According to another aspect of the invention, an optical display may comprise the polarizing plate set forth above.

Exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It is to be understood that the invention is not limited to the embodiments described herein, and that the invention may be practiced in various ways. In the drawings, portions that are not related to the description will be omitted for clarity. Throughout the specification, like reference numerals will be used to refer to the like.

As used herein, the term "(meth)acryloyl) may mean propylene fluorenyl and/or methacryl fluorenyl, and the term "(meth) acrylate" may refer to acrylate and/or methacrylate. As used herein, directional terms such as "upper" and "lower" are defined with reference to the drawings. Therefore, it should be understood that the term "upper surface" may be used interchangeably with the term "lower surface."

Hereinafter, an adhesive film for a polarizing plate according to an embodiment of the present invention will be described in detail.

The adhesive film for the polarizing plate can suppress light leakage due to dimensional changes of the polarizing plate under high temperature and/or high humidity. The adhesive film for the polarizing plate can suppress light leakage through stress suppression and optical compensation. In addition, the adhesive film for the polarizing plate can suppress light leakage in the center portion of the screen of the large-sized display and even at the distal end or the tip end thereof.

When the polarizing plate includes a polarizer and a polarizer protective layer (optical film, coating, or the like) formed on at least one surface of the polarizer, an adhesive film for the polarizing plate is used to fix the polarizing plate to the optical On the panel of the display or on another optical film. The adhesive film for the polarizing plate may have a K value of 0.2 to 0.5 as calculated by the following Equation 1: <Equation 1> K = ∆G' × ∆R ₀ where ∆G' is defined by Equation 2 and ∆R ₀ is defined by Equation 3. <Equation 2>∆G' = G1 - G2 where G1 is the storage modulus at 23 ° C (unit: MPa) and G2 is the storage modulus at 85 ° C (unit: MPa), as passed in The temperature was increased from 0 ° C to 100 ° C at a rate of 10 ° C / min, using a high-grade rheology measurement expansion system at a strain of 5%, a normal force of 100 Newtons, and an angular frequency of 1 rad/sec. (ARES, TA Instruments) conducted a temperature scan test to measure the adhesion of a 500 micron thick adhesive film for a polarizing plate. <Equation 3> ∆R ₀ = R ₀₁ - R ₀₂ wherein R ₀₁ is a retardation (unit: nanometer) at a wavelength of 590 nm at 85 ° C and R ₀₂ is a retardation at a wavelength of 590 nm at 23 ° C ( Unit: nanometer), for example, when the temperature is raised from 0 ° C to 100 ° C at a rate of 10 ° C / min, when applying a stress of 125 mN / 15 mm to a 1 mm thick adhesive film for a polarizing plate measured.

The storage modulus and retardation (R ₀ ) of the adhesive film for a polarizing plate were measured using an adhesive film sample of 500 μm to 1 mm thick by applying an adhesive composition for a polarizing plate to A release film (for example, a polyethylene terephthalate film) reaches a thickness of 50 μm, and is aged at 20 ° C to 100 ° C for 1 minute to 7 days to form a 50 μm thick adhesive film, followed by stacking the adhesion. Membrane to get.

The K value is used to confirm the following measurement values: when the temperature is changed from 23 ° C to 85 ° C, the adhesive film for the polarizing plate has an optical compensation effect of molecular alignment at the end thereof via the adhesive film, and has The stress relaxation effect due to the high storage modulus at a high temperature, thereby suppressing light leakage not only in the central portion of the adhesive film for the polarizing plate but also at the distal end or the tip end thereof.

The K value of the adhesive film for the polarizing plate may be 0.2 to 0.5. Within this range, the adhesive film for the polarizing plate has an excellent light leakage suppressing effect. Thus, the K value of the adhesive film for the polarizing plate is 0.2 to 0.5, whereby even at the end or tip of the adhesive film (where the stress is greater than the stress in the central portion of the adhesive film), optical compensation by molecular arrangement is simultaneously performed, Light leakage is suppressed by suppressing stress. In one embodiment, the K value of the adhesive film for the polarizing plate may be 0.2 to 0.45, such as 0.2, 0.25, 0.3, 0.35, 0.4, 0.45 or 0.5.

As defined in Equation 1, the G1 of the adhesive film for the polarizing plate may be 0.45 MPa or more than 0.45 MPa, for example, 0.45 MPa to 1.0 MPa. Within this range, the adhesive film for the polarizing plate can improve the cuttability of the polarizing plate at room temperature. For example, the G1 of the adhesive film for the polarizing plate may be 0.45 MPa, 0.46 MPa, 0.47 MPa, 0.48 MPa, 0.49 MPa, 0.50 MPa, 0.51 MPa, 0.52 MPa, 0.53 MPa, 0.54 MPa, 0.55 MPa, 0.56 MPa. , 0.57 MPa, 0.58 MPa, 0.59 MPa, 0.6 MPa, 0.65 MPa, 0.7 MPa, 0.75 MPa, 0.8 MPa, 0.85 MPa, 0.9 MPa, 0.95 MPa or 1.0 MPa.

Further, as defined in the equation 1, the G2 of the adhesive film for the polarizing plate may be from 0.01 MPa to 0.3 MPa. Within this range, the adhesive film for the polarizing plate can suppress stress even at a high temperature, and thus suppress light leakage. For example, the G2 of the adhesive film for the polarizing plate may be 0.01 MPa, 0.02 MPa, 0.03 MPa, 0.04 MPa, 0.05 MPa, 0.06 MPa, 0.07 MPa, 0.08 MPa, 0.09 MPa, 0.1 MPa, 0.15 MPa, 0.2 MPa. , 0.25 MPa or 0.3 MPa.

In one embodiment, R ₀₁ and R ₀₂ for the adhesive film of the polarizing plate may be 0 nm to 10 nm, such as 0 nm, 0.01 nm, 0.1 nm, 0.2 nm, 0.3 nm, 0.4 nm, 0.5 nm, 0.6. Nano, 0.7, 0.8, 0.9, 1, 1, 2, 3, 4, 5, 6, 7, 7, 8, or 10 nm.

Specifically, since the adhesive film for the polarizing plate has a high G2 in addition to the K value as explained above, the adhesive film can suppress stress even at a high temperature, and thus suppress light leakage.

The adhesive film for the polarizing plate can be realized by the adhesive composition for a polarizing plate according to an embodiment of the present invention. Hereinafter, an adhesive composition for a polarizing plate according to an embodiment of the present invention will be described in detail.

The adhesive composition for a polarizing plate may comprise (A) a crosslinkable (meth)acrylic copolymer containing a crosslinkable functional group, and (B) a noncrosslinkable (meth)acrylic acid having a positive birefringence Copolymers and (C) curing agents.

(A) a crosslinkable (meth)acrylic copolymer containing a crosslinkable functional group can achieve a crosslinked structure by a curing agent to increase the storage modulus of the adhesive film, thereby suppressing the high temperature and/or due to the polarizing plate Stress caused by dimensional changes under high humidity to suppress light leakage. The "crosslinkable functional group" may include, but is not limited to, at least one of a hydroxyl group and a carboxylic acid group.

(A) The crosslinkable (meth)acrylic copolymer may be a copolymer of a first monomer mixture comprising a monomer having a crosslinkable functional group. The monomer having a crosslinkable functional group may be present in the first monomer mixture in an amount of from 1% by weight to 20% by weight. Within this range, the adhesive film can exhibit an increased storage modulus, thus suppressing light leakage. In one embodiment, the crosslinkable functional group-containing monomer may be present in an amount from 3% by weight to 10% by weight. For example, the monomer having a crosslinkable functional group may be 1% by weight, 2% by weight, 3% by weight, 4% by weight, 5% by weight, 6% by weight, 7% by weight, 8% by weight, and 9% by weight, It is present in an amount of 10% by weight, 11% by weight, 12% by weight, 13% by weight, 14% by weight, 15% by weight, 16% by weight, 17% by weight, 18% by weight, 19% by weight or 20% by weight.

Specifically, the monomer having a crosslinkable functional group may include at least one of a hydroxyl group-containing (meth)acrylic monomer and a carboxylic acid group-containing (meth)acrylic monomer.

In one embodiment, the hydroxyl group-containing (meth)acrylic monomer may be a C ₁ to C ₂₀ alkyl group having a hydroxyl group in its structure or terminal, a C ₅ to C ₂₀ cycloalkyl group or a C ₆ to C group. ₂₀ aryl (meth) acrylate. For example, the hydroxyl group-containing (meth)acrylic monomer may include, but is not limited to, at least one of the following: 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 1,4-cyclohexanedimethanol mono(meth)acrylate, 1-chloro-2-hydroxypropyl (meth)acrylate, diethylene glycol mono(meth)acrylate, 1,6-hexanediol mono(meth)acrylate, pentaerythritol tri(meth)acrylate Dipentaerythritol penta (meth) acrylate, neopentyl glycol mono (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylol ethane di (meth) acrylate, 2-Hydroxy-3-phenoxypropyl (meth)acrylate, 4-hydroxycyclopentyl (meth)acrylate, 4-hydroxycyclohexyl (meth)acrylate, and cyclohexanedimethanol mono(methyl) )Acrylate. These monomers may be used singly or in combination.

In one embodiment, the hydroxyl group-containing (meth)acrylic monomer may be present in the (A) crosslinkable (meth)acrylic copolymer, optionally in an amount of 10% by weight or less. Within this range, the adhesive film can suppress light leakage. For example, the hydroxyl group-containing (meth)acrylic monomer may be present in an amount from 0.1% to 10% by weight, such as from 0.1% to 5% by weight. In one embodiment, the hydroxyl group-containing (meth)acrylic monomer may be present in an amount from 0.1% to 2% by weight. For example, the hydroxyl group-containing (meth)acrylic monomer may be absent or may be 0.1% by weight, 0.5% by weight, 1% by weight, 1.5% by weight, 2% by weight, 2.5% by weight, 3% by weight, 3.5% by weight. %, 4% by weight, 4.5% by weight, 5% by weight, 5.5% by weight, 6% by weight, 6.5% by weight, 7% by weight, 7.5% by weight, 8% by weight, 8.5% by weight, 9% by weight, 9.5% by weight or An amount of 10% by weight is present in the (A) crosslinkable (meth)acrylic copolymer.

The carboxylic acid group-containing (meth)acrylic monomer may include, but is not limited to, (meth)acrylic acid and β-carboxyethyl (meth)acrylate. These monomers may be used singly or in combination.

In one embodiment, the carboxylic acid group-containing (meth)acrylic monomer may be optionally present in (A) crosslinkable (meth)acrylic copolymer in an amount of 10% by weight or less. in. Within this range, the adhesive composition can suppress light leakage. For example, the carboxylic acid group-containing (meth)acrylic monomer may be present in an amount of from 0.1% by weight to 10% by weight, for example from 1% by weight to 6% by weight. For example, the carboxylic acid group-containing (meth)acrylic monomer may be absent or may be 0.1% by weight, 0.5% by weight, 1% by weight, 1.5% by weight, 2% by weight, 2.5% by weight, 3% by weight, 3.5% by weight, 4% by weight, 4.5% by weight, 5% by weight, 5.5% by weight, 6% by weight, 6.5% by weight, 7% by weight, 7.5% by weight, 8% by weight, 8.5% by weight, 9% by weight, 9.5 by weight An amount of % or 10% by weight is present in the (A) crosslinkable (meth)acrylic copolymer.

In one embodiment, the hydroxyl group-containing (meth)acrylic monomer and the carboxylic acid group-containing (meth)acrylic monomer may be present in (A) crosslinkable in an amount of from 3% by weight to 6% by weight ( In the methyl)acrylic copolymer.

In another embodiment, the monomer mixture for the (A) crosslinkable (meth)acrylic copolymer may further comprise an alkyl group-containing (meth)acrylic monomer. The alkyl group-containing (meth)acrylic monomer serves to improve the mechanical properties and reliability of the adhesive film, and may contain a linear or branched C ₁ to C ₂₀ alkyl group-containing (meth) acrylate. For example, the alkyl group-containing (meth)acrylic monomer may include, but is not limited to, at least one of the following: methyl (meth)acrylate, ethyl (meth)acrylate, (meth)acrylic acid Propyl ester, n-butyl (meth)acrylate, tert-butyl (meth)acrylate, isobutyl (meth)acrylate, amyl (meth)acrylate, hexyl (meth)acrylate, (methyl) 2-ethylhexyl acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, decyl (meth)acrylate and Dodecyl methacrylate. These monomers may be used singly or in combination.

In one embodiment, the alkyl group-containing (meth)acrylic monomer may be present in the first monomer mixture in an amount of from 80% by weight to 99% by weight in this range, and the adhesive film exhibits excellent reliability. . For example, the alkyl group-containing (meth)acrylic monomer may be present in an amount of from 90% by weight to 97% by weight. For example, the alkyl group-containing (meth)acrylic monomer may be 80% by weight, 81% by weight, 82% by weight, 83% by weight, 84% by weight, 85% by weight, 86% by weight, 87% by weight, 88. It is present in an amount of % by weight, 89% by weight, 90% by weight, 91% by weight, 92% by weight, 93% by weight, 94% by weight, 95% by weight, 96% by weight, 97% by weight, 98% by weight or 99% by weight.

The (A) crosslinkable (meth)acrylic copolymer may be a non-aromatic (meth)acrylic copolymer containing no aromatic group. As described above, even in the case where the (A) crosslinkable (meth)acrylic copolymer does not contain an aromatic group, the adhesive film may be copolymerized by (B) non-crosslinkable (meth)acrylic acid. The presence of matter suppresses light leakage.

The weight average molecular weight of the (A) crosslinkable (meth)acrylic copolymer may be, but is not limited to, less than 1,000,000 g/mole. Specifically, the weight average molecular weight of the (A) crosslinkable (meth)acrylic copolymer may be from 300,000 g/mol to less than 1,000,000 g/mole.

Although the (B) non-crosslinkable (meth)acrylic copolymer having positive birefringence is not crosslinked by a curing agent, the (B) non-crosslinkable (meth)acrylic copolymer is crosslinkable The (meth)acrylic copolymer combines to form an interpenetrating polymer network (IPN) structure, thereby improving the storage modulus of the adhesive film. In addition, when the polarizing plate changes in size at high temperature and/or high humidity, since (B) the non-crosslinkable (meth)acrylic copolymer is not crosslinked, its molecule can be crosslinked (A). Those molecules of the methyl)acrylic copolymer are more easily aligned. Here, the negative birefringence of the adhesive film and the (meth)acrylic adhesive resin is canceled by the positive birefringence due to the arrangement of the aromatic groups, thereby suppressing light leakage via optical compensation.

Specifically, the (B) non-crosslinkable (meth)acrylic copolymer may be a copolymer of a second monomer mixture comprising an aromatic group-containing (meth)acrylic monomer.

The aromatic group-containing (meth)acrylic monomer may be present in the second monomer mixture in an amount of from 5 to 50% by weight. Within this range, the adhesive film may have an optical compensation effect of molecular alignment via high temperature, thereby suppressing light leakage. For example, the aromatic group-containing (meth)acrylic monomer may be present in an amount of from 5% by weight to 35% by weight. For example, the aromatic group-containing (meth)acrylic monomer may be 5% by weight, 6% by weight, 7% by weight, 8% by weight, 9% by weight, 10% by weight, 11% by weight, and 12% by weight, 13% by weight, 14% by weight, 15% by weight, 16% by weight, 17% by weight, 18% by weight, 19% by weight, 20% by weight, 21% by weight, 22% by weight, 23% by weight, 24% by weight, and 25% by weight %, 26% by weight, 27% by weight, 28% by weight, 29% by weight, 30% by weight, 31% by weight, 32% by weight, 33% by weight, 34% by weight, 35% by weight, 36% by weight, 37% by weight, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49% or 50% by weight The amount of % exists.

The aromatic group-containing (meth)acrylic monomer can be represented by Formula 1: <Formula 1> Wherein Y is hydrogen or methyl, p is an integer from 0 to 10, and X is selected from the group consisting of phenoxy, phenyl, methylphenyl, methylethylphenyl, methoxy Phenyl, propylphenyl, cyclohexylphenyl, chlorophenyl, bromophenyl, phenylphenyl, benzyl and benzylphenyl.

Further, the aromatic group-containing (meth)acrylic monomer may include, but is not limited to, at least one of the following: phenoxyethyl (meth)acrylate, phenyl (meth)acrylate, (methyl) Phenyloxyacrylate, 2-ethylphenoxy (meth)acrylate, benzyl (meth)acrylate, 2-phenylethyl (meth)acrylate, 3-phenylpropyl (meth)acrylate, 4-Phenylbutyl (meth)acrylate, 2-2-methylphenylethyl (meth)acrylate, 2-methylphenylethyl (meth)acrylate, 2-(meth)acrylate 4-methylphenylethyl ester, 2-(4-propylphenyl)ethyl (meth)acrylate, 2-(4-(1-methylethyl)phenyl)ethyl (meth)acrylate , 2-(4-methoxyphenyl)ethyl (meth)acrylate, 2-(4-cyclohexylphenyl)ethyl (meth)acrylate, 2-(2-chlorophenyl) (meth)acrylate Ethyl ester, 2-(3-chlorophenyl)ethyl (meth)acrylate, 2-(4-chlorophenyl)ethyl (meth)acrylate, 2-(4-bromobenzene) (meth)acrylate Ethyl ester, 2-(3-phenylphenyl)ethyl (meth)acrylate, benzyl (meth)acrylate and 2-(4-benzylphenyl)ethyl (meth)acrylate .

In one embodiment, the second monomer mixture for the (B) non-crosslinkable (meth)acrylic copolymer may further comprise an alkyl group-containing (meth)acrylic monomer. The alkyl group-containing (meth)acrylic monomer may be included to improve the mechanical properties and reliability of the adhesive film. For example, the second monomer mixture may contain a linear or branched chain containing C ₁ to C ₂₀ alkyl group of the (meth) acrylate.

The alkyl group-containing (meth)acrylic monomer may be present in the second monomer mixture in an amount of from 0.1% by weight to 50% by weight. Within this range, the adhesive film ensures reliability. For example, the alkyl group-containing (meth)acrylic monomer may be present in an amount of from 1% by weight to 20% by weight. For example, the alkyl group-containing (meth)acrylic monomer may be 0.1% by weight, 0.2% by weight, 0.3% by weight, 0.4% by weight, 0.5% by weight, 0.6% by weight, 0.7% by weight, 0.8% by weight, 0.9. % by weight, 1% by weight, 2% by weight, 3% by weight, 4% by weight, 5% by weight, 6% by weight, 7% by weight, 8% by weight, 9% by weight, 10% by weight, 11% by weight, and 12% by weight 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25 Weight%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37% by weight 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49% or 50 The amount by weight is present.

In one embodiment, the second monomer mixture for the (B) non-crosslinkable (meth)acrylic copolymer may further comprise a (meth)acrylic monomer represented by Formula 2: <Formula 2> Wherein A is an aliphatic hydrocarbon group; B is -O- or -S-; R ₁ is hydrogen or methyl; R ₂ is a C ₁ to C ₂₀ aliphatic hydrocarbon group; and n is an integer of 1 to 5.

In one embodiment, A may be a C ₁ to C ₁₀ aliphatic hydrocarbon group, specifically a linear or branched C ₁ to C ₁₀ alkyl group, more specifically a linear or branched chain C ₁ to C. ₅ alkyl groups, and R ₂ may be a C ₁ to C ₁₀ aliphatic hydrocarbon group, specifically a C ₁ to C ₁₀ alkyl group, more specifically a linear or branched C ₁ to C ₅ alkyl group. For example, the (meth)acrylic monomer represented by Formula 2 may be, but not limited to, 2-(2-ethoxyethoxy)ethyl (meth)acrylate.

The monomer represented by Formula 2 can be synthesized by a typical method, or can be commercially available. The monomer represented by Formula 2 is contained in (B) a non-crosslinkable (meth)acrylic copolymer, whereby the adhesive film can exhibit improved optical characteristics to improve light leakage and ensure adhesion. The monomer represented by Formula 2 may be present in the second monomer mixture in an amount of from 10% by weight to 85% by weight. Within this range, the adhesive film can suppress light leakage. In one embodiment, the monomer represented by Formula 2 may be present in an amount from 55% by weight to 80% by weight. For example, the monomer represented by Formula 2 may be 10% by weight, 11% by weight, 12% by weight, 13% by weight, 14% by weight, 15% by weight, 16% by weight, 17% by weight, 18% by weight, and 19% by weight. %, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31% by weight, 32% by weight, 33% by weight, 34% by weight, 35% by weight, 36% by weight, 37% by weight, 38% by weight, 39% by weight, 40% by weight, 41% by weight, 42% by weight, 43% by weight, 44% by weight %, 45% by weight, 46% by weight, 47% by weight, 48% by weight, 49% by weight, 50% by weight, 51% by weight, 52% by weight, 53% by weight, 54% by weight, 55% by weight, 56% by weight, 57% by weight, 58% by weight, 59% by weight, 60% by weight, 61% by weight, 62% by weight, 63% by weight, 64% by weight, 65% by weight, 66% by weight, 67% by weight, 68% by weight, 69% by weight %, 70% by weight, 71% by weight, 72% by weight, 73% by weight, 74% by weight, 75% by weight, 76% by weight, 77% by weight, 78% by weight, 79% by weight, 80% by weight, 81% by weight, An amount of 82% by weight, 83% by weight, 84% by weight or 85% by weight is present.

Therefore, the adhesive film for the polarizing plate may contain a functional group represented by Formula 3: <Formula 3> Wherein * represents a binding site, and A, B, R ₂ and n are as defined in Formula 2.

In one embodiment, the (B) non-crosslinkable (meth)acrylic copolymer may be a copolymer of a monomer mixture comprising a monomer having a crosslinkable functional group. Specifically, the monomer having a crosslinkable functional group may include at least one of the hydroxyl group-containing (meth)acrylic monomer described above and the carboxylic acid group-containing (meth)acrylic monomer. In one embodiment, the crosslinkable functional group-containing monomer can be optionally present in the monomer mixture in an amount less than 1% by weight. For example, a monomer having a crosslinkable functional group may be absent or may be 0.005% by weight, 0.01% by weight, 0.02% by weight, 0.03% by weight, 0.04% by weight, 0.05% by weight, 0.06% by weight, 0.07% by weight, An amount of 0.08 wt%, 0.09 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt% or less than 1 wt% presence.

(B) The non-crosslinkable (meth)acrylic copolymer may have a weight average molecular weight of less than 1,000,000 g/mole. Within this range, the adhesive film can suppress light leakage. Specifically, the weight average molecular weight of the (B) non-crosslinkable (meth)acrylic copolymer may be from 300,000 g/mol to less than 1,000,000 g/mole.

The (A) crosslinkable (meth)acrylic acid, based on 100 parts by weight of (A) a crosslinkable (meth)acrylic copolymer and (B) a non-crosslinkable (meth)acrylic copolymer The copolymer may be present in an amount of from 60 parts by weight to 95 parts by weight, and the (B) non-crosslinkable (meth)acrylic copolymer may be present in an amount of from 5 parts by weight to 40 parts by weight. Within this range, the adhesive film can suppress light leakage due to stress suppression and optical compensation. Specifically, (A) the crosslinkable (meth)acrylic copolymer may be present in an amount of 70 parts by weight to 90 parts by weight, and (B) the non-crosslinkable (meth)acrylic copolymer may be 10 parts by weight. It is present in an amount of 30 parts by weight.

For example, the (A) crosslinkable (meth)acrylic copolymer may be 60 parts by weight, 61 parts by weight, 62 parts by weight, 63 parts by weight, 64 parts by weight, 65 parts by weight, 66 parts by weight, 67 parts by weight. 68 parts by weight, 69 parts by weight, 70 parts by weight, 71 parts by weight, 72 parts by weight, 73 parts by weight, 74 parts by weight, 75 parts by weight, 76 parts by weight, 77 parts by weight, 78 parts by weight, 79 parts by weight, 80 parts by weight Parts by weight, 81 parts by weight, 82 parts by weight, 83 parts by weight, 84 parts by weight, 85 parts by weight, 86 parts by weight, 87 parts by weight, 88 parts by weight, 89 parts by weight, 90 parts by weight, 91 parts by weight, 92 parts by weight It is present in an amount of 93 parts by weight, 94 parts by weight or 95 parts by weight. Further, the (B) non-crosslinkable (meth)acrylic copolymer may be 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, or 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, 20 parts by weight, 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight Parts, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight, 30 parts by weight, 31 parts by weight, 32 parts by weight, 33 parts by weight, 34 parts by weight, 35 parts by weight, 36 parts by weight, 37 parts by weight, It is present in an amount of 38 parts by weight, 39 parts by weight or 40 parts by weight.

The monomer mixture of (A) the crosslinkable (meth)acrylic copolymer and the (B) non-crosslinkable (meth)acrylic copolymer may further comprise an alicyclic group-containing (methyl) group. At least one of an acrylic monomer and a heterocyclic-containing (meth)acrylic monomer.

The alicyclic group-containing (meth)acrylic monomer is a (meth) acrylate containing a C ₃ to C ₁₀ alicyclic group, and specifically may comprise isobornyl (meth) acrylate, (methyl) Cyclohexyl acrylate and the like. The alicyclic group-containing (meth)acrylic monomer may be present in (A) a crosslinkable (meth)acrylic copolymer and (B) a non-crosslinkable (A) in an amount of 10% by weight or less. Each of the acrylic copolymers. Within this range, the adhesive film can exhibit improved durability and good reworkability. For example, the alicyclic group-containing (meth)acrylic monomer may be optionally present in an amount of 5% by weight or less. For example, the alicyclic group-containing (meth)acrylic monomer may be absent or may be 0.1% by weight, 0.2% by weight, 0.3% by weight, 0.4% by weight, 0.5% by weight, 1% by weight, 2% by weight, It is present in an amount of 3% by weight, 4% by weight, 5% by weight, 6% by weight, 7% by weight, 8% by weight, 9% by weight or 10% by weight.

The heterocyclic-containing (meth)acrylic monomer may be a C ₂ to C ₁₀ aliphatic or alicyclic saturated or unsaturated heterocyclic ring or C having a hetero atom (for example, at least one of nitrogen, oxygen, and sulfur). A monomer of ₄ to C ₂₀ aromatic heterocyclic ring. For example, the heterocyclic-containing (meth)acrylic monomer may comprise acryloylmorpholine. The heterocyclic-containing (meth)acrylic monomer may be present in (A) a crosslinkable (meth)acrylic copolymer and (B) a non-crosslinkable (methyl) in an amount of 10% by weight or less. ) in each of the acrylic copolymers. Within this range, the adhesive film can exhibit improved durability and good reworkability. For example, the heterocyclic-containing (meth)acrylic monomer may optionally be present in an amount of 5% by weight or less. For example, the heterocyclic-containing (meth)acrylic monomer may be absent or may be 0.1% by weight, 0.2% by weight, 0.3% by weight, 0.4% by weight, 0.5% by weight, 1% by weight, 2% by weight, 3 It is present in an amount of % by weight, 4% by weight, 5% by weight, 6% by weight, 7% by weight, 8% by weight, 9% by weight or 10% by weight.

The (meth)acrylic copolymer can be prepared using, but not limited to, solution polymerization, photopolymerization, bulk polymerization, emulsion polymerization. Preferably, the (meth)acrylic copolymer is prepared by solution polymerization at a temperature of from 50 ° C to 140 ° C for from 5 hours to 24 hours. The initiator used in the polymerization may be a typical initiator comprising: an azo polymerization initiator such as azobisisobutyronitrile and azobiscyclohexylcarbonitrile; a peroxide such as benzamidine peroxide and Oxidized acetonitrile; and so on. The initiator may be present in an amount of from 0.1 part by weight to 10 parts by weight based on 100 parts by weight of the alkyl group-containing (meth)acrylic monomer. Within this range, the copolymer can be sufficiently polymerized. The solvent used in the polymerization may include, but is not limited to, at least one of ethyl acetate and methyl ethyl ketone. For example, the solvent may be 0.01 parts by weight, 0.05 parts by weight, 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, It is present in an amount of 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight or 10 parts by weight.

The (meth)acrylic copolymer may be present in the adhesive composition for a polarizing plate in an amount of from 90% by weight to 99% by weight based on the solid content. Within this range, the adhesive composition has an advantage in film formation, and when the components of the adhesive composition are mixed, the distribution of the components is uniform. For example, the (meth)acrylic copolymer may be 90% by weight, 91% by weight, 92% by weight, 93% by weight, 94% by weight, 95% by weight, 96% by weight, 97% by weight, 98% by weight or 99% The amount by weight is present.

The curing agent cures the (meth)acrylic copolymer, and may include at least one of the following: an isocyanate curing agent, an epoxide curing agent, an aziridine curing agent, a melamine curing agent, an amine curing agent, and an amide imine curing. Agent, carbodiimide curing agent and guanamine curing agent. Specifically, the curing agent may contain a polyfunctional curing agent to improve stress suppression by increasing the storage modulus of the adhesive film by crosslinking thereof with the crosslinkable (meth)acrylic copolymer.

The isocyanate curing agent may include, but is not limited to, hexamethylene diisocyanate (HDI); toluene diisocyanate (TDI), containing 2,4-toluene diisocyanate, 2,6-toluene diisocyanate 4,4'-methylene diphenyl diisocyanate (MDI); xylene diisocyanate (XDI), containing 1,3-xylene diisocyanate, 1,4-dimethylbenzene Isocyanate; hydrogenated phenylene diisocyanate; isophorone diisocyanate; 1,3-bisisocyanatomethylcyclohexane; tetramethylxylene diisocyanate; 1,5-naphthalene diisocyanate; Methylene diisocyanate; 2,2,4-trimethylhexamethylene diisocyanate; 2,4,4-trimethylhexamethylene diisocyanate; toluene diisocyanate modified with trimethylolpropane; Methylphenylene diisocyanate modified by trimethylolpropane; methylphenylene diisocyanate adduct of trimethylolpropane; xylene diisocyanate adduct of trimethylolpropane; triphenyl Methane triisocyanate Ester; and methylene bis (triisocyanate). These curing agents may be used singly or in combination.

The curing agent may be present in an amount of from 0.1 part by weight to 10 parts by weight based on 100 parts by weight of the total of (A) the crosslinkable (meth)acrylic copolymer and the (B) non-crosslinkable (meth)acrylic copolymer. . Within this range, the adhesive composition can exhibit excellent durability and exhibit small composition and property changes over time. Specifically, the curing agent may be present in an amount of from 5 parts by weight to 8 parts by weight. For example, the curing agent may be 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1 part by weight, and 2 parts by weight. It is present in an amount of 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight or 10 parts by weight.

The curing agent may be present in the adhesive composition for the polarizing plate in an amount of from 1% by weight to 10% by weight based on the solid content. Within this range, the adhesive composition can exhibit excellent durability and exhibit small composition and property changes over time. For example, the curing agent may be present in an amount from 0.1% to 9% by weight, such as from 5% to 8% by weight. For example, the curing agent may be present in an amount of 1%, 2%, 3%, 3%, 5%, 6%, 7%, 8%, 9%, or 10% by weight.

The adhesive composition for the polarizing plate may further contain a decane coupling agent. The decane coupling agent is contained in the adhesive composition, thereby improving the moisture resistance and the moist heat resistance of the adhesive film for the polarizing plate.

The decane coupling agent can be a typical decane coupling agent known to those skilled in the art. For example, the decane coupling agent may include, but is not limited to, an oxime compound having an epoxy structure, such as 3-glycidoxypropyltrimethoxydecane, 3-glycidoxypropylmethyl dimethyl Oxydecane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxydecane; an anthracene compound containing a polymerizable unsaturated group, such as vinyltrimethoxydecane, vinyltriethoxydecane , (meth) propylene methoxy propyl trimethoxy decane; amino group-containing hydrazine compound, such as 3-aminopropyltrimethoxy decane, N-(2-aminoethyl)-3-aminopropyltrimethoxy Basear, N-(2-aminoethyl)-3-aminopropylmethyldimethoxydecane; and 3-chloropropyltrimethoxydecane. These decane coupling agents may be used singly or in combination thereof. Preferably, the decane coupling agent is a decane coupling agent containing an epoxy structure.

The decane coupling agent may be in an amount of from 0.1 part by weight to 5 parts by weight based on 100 parts by weight of the (A) crosslinkable (meth)acrylic copolymer and (B) non-crosslinkable (meth)acrylic copolymer. presence. Within this range, the adhesive composition can exhibit excellent durability and exhibit small composition and property changes over time. Specifically, the decane coupling agent may be present in an amount of from 0.1 part by weight to 0.5 part by weight. For example, the decane coupling agent may be 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1 part by weight, 2 parts by weight. It is present in an amount of parts by weight, 3 parts by weight, 4 parts by weight or 5 parts by weight.

The decane coupling agent may be present in the adhesive composition for a polarizing plate in an amount of from 0.1% by weight to 9% by weight based on the solid content. Within this range, the adhesive composition can exhibit excellent adhesion to the liquid crystal panel, and the (meth)acrylic copolymer can exhibit excellent storage stability. For example, the decane coupling agent may be present in an amount from 0.1% to 1% by weight. For example, the decane coupling agent may be 0.1% by weight, 0.2% by weight, 0.3% by weight, 0.4% by weight, 0.5% by weight, 0.6% by weight, 0.7% by weight, 0.8% by weight, 0.9% by weight, 1% by weight, 2 It is present in an amount of % by weight, 3% by weight, 4% by weight, 5% by weight, 6% by weight, 7% by weight, 8% by weight or 9% by weight.

The adhesive composition for the polarizing plate may further contain a solvent. The solvent may include, but is not limited to, methyl ethyl ketone and the like. The adhesive composition for the polarizing plate may further contain typical additives such as a UV absorber, an antioxidant, and the like.

The viscosity of the adhesive composition for a polarizing plate at 25 ° C may be 1,000 cPs to 6,000 cPs. Within this range, the adhesive composition allows easy adjustment of the thickness of the adhesive film, and the adhesive film does not have stains, and a uniform coating surface can be obtained.

The adhesive film for a polarizing plate according to the present invention can be produced by drying and/or aging the adhesive composition for a polarizing plate as explained above. Specifically, the aging of the adhesive composition can be carried out by thermal curing of the adhesive composition or by separately storing the adhesive composition at 20 ° C to 35 ° C for 1 hour to 1 week, but is not limited thereto. For example, an adhesive film for a polarizing plate may be applied onto a release film (for example, a polyethylene terephthalate film), followed by drying, and then cured at 20 ° C to 35 ° C, thereby manufacturing a manufacturing facility Adhesive film.

The thickness of the adhesive film for the polarizing plate may be 5 micrometers to 200 micrometers. Within this thickness range, the adhesive film can be used for the purpose of an adhesive film for a polarizing plate.

According to an embodiment of the present invention, the polarizing plate comprises an adhesive film for a polarizing plate as described above or an adhesive layer formed of an adhesive composition for a polarizing plate as set forth above. Hereinafter, a polarizing plate according to an embodiment will be described in detail with reference to FIG. 1.

Referring to FIG. 1, a polarizing plate 100 according to an embodiment of the present invention may include: a polarizer 1; a first protective film 2 formed on an upper surface of the polarizer 1, and a lower surface of the polarizer 1. a second protective film 3; and a first adhesive film 4 formed on a lower surface of the second protective film 3, wherein the first adhesive film 4 may be adhered to a polarizing plate according to an embodiment of the present invention A film or an adhesive composition for a polarizing plate is formed.

Regardless of the method of making the polyvinyl alcohol film, the polarizer may comprise any polyvinyl alcohol film. For example, the polarizer may comprise a modified polyvinyl alcohol film such as a partially formalized polyvinyl alcohol film, a polyvinyl alcohol film modified with an ethylene oxime group, or the like. Specifically, the polarizer is produced by dyeing a polyvinyl alcohol film with iodine or a dichroic dye, and then stretching the polyvinyl alcohol film in a certain direction. Specifically, the polarizer is produced by swelling, dyeing, and stretching. One method of performing such processes is generally known to those skilled in the art. For example, the thickness of the polarizer can be, but is not limited to, 10 microns to 50 microns. Within this range, the polarizer can be used for an optical display.

Each of the first protective film and the second protective film may be stacked on one surface of the polarizer. The first protective film and the second protective film may be the same or different. The first protective film and the second protective film may comprise a cyclic olefin polymer (COP) film comprising an amorphous cycloolefin polymer film; a poly(meth)acrylate film; a polycarbonate film; a polyester Membrane comprising polyethylene terephthalate (PET) film; polyether ruthenium film; polyfluorene film; polyamide film; polyimine film; polyolefin film; polyarylate film; An alcohol film; a polyvinyl chloride film; a polyvinylidene chloride film and a mixture thereof. The thickness of the protective film may be from 10 micrometers to 200 micrometers, such as, but not limited to, 30 micrometers to 120 micrometers. Within this range, a protective film can be used for an optical display.

The adhesive film may be formed by applying an adhesive composition according to an embodiment to one surface of the protective film, followed by drying and/or curing. The thickness of the adhesive film may be from 5 micrometers to 100 micrometers.

The first adhesive film 4 is stacked on one surface of a liquid crystal display panel (not shown in FIG. 1) to fix the polarizing plate to the liquid crystal display panel.

In addition, although not shown in FIG. 1, an adhesive layer may be formed between the polarizer 1 between the first protective film 2 and between the polarizer 1 and the second protective film 3, and may be typically bonded by a polarizing plate. Agent to form. Specifically, the adhesive for the polarizing plate may include a water-based adhesive (including a polyvinyl alcohol resin) and a photocurable adhesive (including a (meth)acrylic adhesive resin).

Hereinafter, a polarizing plate according to another embodiment of the present invention will be described in detail with reference to FIG. 2 is a cross-sectional view of a polarizing plate in accordance with another embodiment of the present invention.

Referring to FIG. 2, a polarizing plate 200 according to another embodiment may include: a polarizer 1; a first protective film 2 formed on an upper surface of the polarizer 1, and a second formed on a lower surface of the polarizer 1. a protective film 3; a first adhesive film 4 formed on a lower surface of the second protective film 3; a third protective film 5 formed on a lower surface of the first adhesive film 4; and a third protective layer stacked on the third protective film a second adhesive film 6 on the lower surface of the film 5, wherein at least one of the first adhesive film 4 and the second adhesive film 6 may be composed of an adhesive for a polarizing plate according to an embodiment of the present invention Object formation. The polarizing plate 200 is substantially the same as the polarizing plate 100 according to the above embodiment except that the polarizing plate 200 according to this embodiment further includes a third protective film and a second adhesive film formed on the lower surface of the first adhesive film. the same.

The third protective film may comprise a cycloolefin polymer (COP) film comprising an amorphous cycloolefin polymer film; a poly(meth)acrylate film; a polycarbonate film; a polyester film comprising polyethylene terephthalate Diester (PET) film; polyether film; polyfluorene film; polyamide film; polyimine film; polyolefin film; polyarylate film; polyvinyl alcohol film; polyvinyl chloride film; Vinyl film and mixtures thereof. The thickness of the protective film may be from 10 micrometers to 200 micrometers, such as, but not limited to, 30 micrometers to 120 micrometers. Within this range, a protective film can be used for an optical display.

The second adhesive film 6 is stacked on one surface of a liquid crystal display panel (not shown in FIG. 2) to fix the polarizing plate to the liquid crystal display panel.

According to an embodiment of the invention, the display may comprise an adhesive film as set forth above or a polarizing plate as set forth above. The display can include a liquid crystal display including, but not limited to, a TFT-LCD.

Hereinafter, an optical display according to an embodiment of the present invention will be described in detail with reference to FIG. 3 is a cross-sectional view of an optical display in accordance with an embodiment of the present invention.

Referring to FIG. 3, an optical display 300 according to an embodiment may include a liquid crystal display panel 310, a first polarizing plate 320 formed on an upper surface of the liquid crystal display panel 310, and a to-be-formed surface formed on the lower surface of the liquid crystal display panel 310. a second polarizing plate 330 disposed between the liquid crystal display panel 310 and the light source unit 340, wherein at least one of the first polarizing plate 320 and the second polarizing plate 330 may be an embodiment according to the present invention Polarizer.

Specifically, the optical display according to the embodiment may be a large display including a liquid crystal display panel of 7 inches or more.

The invention will be described in more detail hereinafter with reference to some examples. It is understood that these examples are provided for illustration only and are not to be construed as limiting the invention in any way. Preparation Example 1 : Preparation of ( meth ) acrylic copolymer

50 g of ethyl acetate, 10 g of methyl ethyl ketone, 95 g of butyl acrylate, 4 g of acrylic acid and 1 g of 2-hydroxyethyl methacrylate were placed in a 1 liter four-necked flask, which was then heated to 70. °C and then kept at 70 °C. 0.06 g of azobisisobutyronitrile corresponding to the initiator was dissolved in 20 g of ethyl acetate, and then introduced into a flask. After reacting at 65 ° C for 3 hours, 170 g of methyl ethyl ketone was added to the obtained material, followed by cooling to 40 ° C, thereby preparing an acrylic copolymer having a viscosity of 4,400 cPs at 25 ° C (Mw: 900,000 g / Moore). Preparation Example 2 : Preparation of ( meth ) acrylic copolymer

50 g of ethyl acetate, 10 g of methyl ethyl ketone, 60 g of 2-(2-ethoxyethoxy)ethyl acrylate, 10 g of butyl acrylate and 30 g of 2-phenoxyethyl acrylate were placed. This was heated in a 1 liter four-necked flask to 70 ° C and then maintained at 70 ° C. 0.06 g of azobisisobutyronitrile corresponding to the initiator was dissolved in 20 g of ethyl acetate, and then introduced into a flask. After reacting at 65 ° C for 3 hours, 170 g of methyl ethyl ketone was added to the obtained material, followed by cooling to 40 ° C, thereby preparing an acrylic copolymer having a viscosity of 4,400 cPs at 25 ° C (Mw: 600,000 g / Moore). Preparation Example 3 : Preparation of ( meth ) acrylic copolymer

50 g of ethyl acetate, 10 g of methyl ethyl ketone, 80 g of 2-(2-ethoxyethoxy)ethyl acrylate, 8 g of butyl acrylate, 7 g of 2-phenoxyethyl acrylate, 4 g of acrylic acid and 1 g of 2-hydroxyethyl methacrylate were placed in a 1 liter four-necked flask, which was then heated to 70 ° C and then maintained at 70 ° C. 0.06 g of azobisisobutyronitrile corresponding to the initiator was dissolved in 20 g of ethyl acetate, and then introduced into a flask. After reacting at 65 ° C for 3 hours, 170 g of methyl ethyl ketone was added to the obtained material, followed by cooling to 40 ° C, thereby preparing an acrylic copolymer having a viscosity of 4,400 cPs at 25 ° C (Mw: 900,000 g / Moore). Preparation Example 4 : Preparation of ( meth ) acrylic copolymer

50 g of ethyl acetate, 10 g of methyl ethyl ketone, 60 g of 2-(2-ethoxyethoxy)ethyl acrylate and 40 g of butyl acrylate were placed in a 1 liter four-necked flask, followed by Heat to 70 ° C and then maintain at 70 ° C. 0.06 g of azobisisobutyronitrile corresponding to the initiator was dissolved in 20 g of ethyl acetate, and then introduced into a flask. After reacting at 65 ° C for 3 hours, 170 g of methyl ethyl ketone was added to the obtained material, followed by cooling to 40 ° C, thereby preparing an acrylic copolymer having a viscosity of 4,400 cPs at 25 ° C (Mw: 900,000 g / Moore). Preparation Example 5 : Preparation of ( meth ) acrylic copolymer

50 g of ethyl acetate, 10 g of methyl ethyl ketone, 65 g of butyl acrylate, 30 g of 2-phenoxyethyl acrylate, 4 g of acrylic acid and 1 g of 2-hydroxyethyl methacrylate were placed in 1 liter. In a four-necked flask, it was then heated to 70 ° C and then maintained at 70 ° C. 0.06 g of azobisisobutyronitrile corresponding to the initiator was dissolved in 20 g of ethyl acetate, and then introduced into a flask. After reacting at 65 ° C for 3 hours, 170 g of methyl ethyl ketone was added to the obtained material, followed by cooling to 40 ° C, thereby preparing an acrylic copolymer having a viscosity of 1,200 cPs at 25 ° C (Mw: 250,000 g / Moore). Example 1

The copolymer of Preparation Example 1 and the copolymer of Preparation Example 2 were mixed in an amount (unit: parts by weight) as listed in Table 1, added to 18 parts by weight of methyl ethyl ketone, followed by stirring at 25 ° C. 30 minutes. Then, 7.1 parts by weight of an isocyanate curing agent (methylated phenylene diisocyanate modified with trimethylolpropane), Model: Colonate-L, Japan Polyurethane Co., Ltd. was further added to the obtained material. (Nippon Polyurethane Co., Ltd.) and 0.5 part by weight of a decane coupling agent (3-glycidoxypropyltrimethoxydecane, model: KBM-403, Shin-Etsu Chemical Co., Ltd. (Shin-Etsu Chemical Co) . , Ltd.)), followed by mixing the components, thereby preparing an adhesive composition for a polarizing plate. The prepared adhesive composition is applied onto a release film (for example, an anthrone-coated polyethylene terephthalate film), followed by drying at 100 ° C for 3 minutes, thereby forming a 20 μm thick layer. Adhesive film on polarizing plate. The adhesive film for the polarizing plate was stacked on a polarizing plate, followed by aging under constant temperature and humidity conditions (35 ° C, 45% relative humidity). Example 2 to Example 5 and Comparative Example 1 to Comparative Example 6

An adhesive composition for a polarizing plate and an adhesive film for a polarizing plate were produced in the same manner as in Example 1 except that the amount of each component in Example 1 was changed as listed in Table 1. Table 1

The adhesive compositions for polarizing plates of the examples and comparative examples and the adhesive films produced by coating and curing were evaluated in terms of the following characteristics. The results are shown in Table 2. Table 2 (1) Change in storage modulus (∆G', unit: MPa)

Each of the adhesive compositions for the polarizing plates prepared in Examples 1 to 5 and Comparative Examples 1 to 6 was applied to a release film (for example, a polyethylene terephthalate film). Then, it was dried at 100 ° C for 3 minutes, thereby forming a 50 μm thick adhesive film for a polarizing plate. The adhesive film was stacked to a thickness of 500 microns and cut into a circular sample having a diameter of 8 mm. High-grade rheology was measured at a strain of 5%, a normal force of 100 Newtons, and an angular frequency of 1 rad/sec while the temperature was raised from 0 °C to 100 °C at a rate of 10 °C/min. The expansion system (ARES, TA Instruments) performed a temperature sweep test to measure the storage modulus (G1) of the sample at 23 ° C and the storage modulus (G2) at 85 ° C. Then, the storage modulus change (∆G') is calculated by the following Equation 2: <Equation 2> ∆G' = G1 - G2 (2) Delay

Each of the adhesive compositions for the polarizing plates prepared in Examples 1 to 5 and Comparative Examples 1 to 6 was applied to a release film (for example, a polyethylene terephthalate film). Then, it was dried at 100 ° C for 3 minutes, thereby forming a 50 μm thick adhesive film for a polarizing plate. The adhesive film was stacked to a thickness of 1,000 μm and cut into a sample having a size of 2 cm × 10 cm × 1,000 μm (width × length × thickness). In the case where both ends of the sample are fixed to a spectroscopic ellipsometer (model: M-220, Japan Spectroscopic Co., Ltd.), the spectral type is made The inside of the ellipsometer was measured at a rate of 10 ° C/min from 0 ° C to 100 ° C while measuring the retardation in the center portion of the sample at a wavelength of 590 nm under a load of 125 millinewtons / 15 mm ( R ₀ ). Measured at 85 ℃ the delay (R ₀₁₎ and retardation (R _02), and calculates a delay variation (ΔR ₀₎ by the following equation 3 at 23 ℃ of: <Equation 3> ΔR ₀ = R ₀₁ - R ₀₂ (3)K

The K value is calculated from the storage modulus change (∆G') and the retardation change (∆R ₀ ) by the following Equation 1. <Equation 1> K value = ∆G' × ∆R ₀ (4) Light leakage

Each of the polarizing plates aged in Examples 1 to 5 and Comparative Examples 1 to 6 was cut into pieces having a size of 1,200 mm × 900 mm (length × width), which were then stacked on a glass substrate. Then, a pressure of 4 kg/cm to 5 kg/cm was applied to the polarizing plate, thereby preparing a polarizing plate sample. The prepared samples (1,200 mm x 900 mm) were attached to both surfaces of a 7-inch TN mode LCD panel such that their optical axes intersect. Then, the LCD panel was stored at 85 ° C for 500 hours and unloaded at room temperature. Then, the LCD panel is observed using a backlight in a dark room to determine whether light leakage has occurred on the LCD panel. Light leakage occurs in the central portion of the LCD panel and at the end portion of the LCD panel. O: It is difficult to determine the light leakage with the naked eye. ∆: slight light leakage X: severe light leakage

(5) Reliability: The polarizing plate on which each of the adhesive films for the polarizing plates prepared in Examples 1 to 5 and Comparative Examples 1 to 6 was coated was cut into a size of 100 mm × 175 Sheets of millimeters (width x length) were then stacked on a glass substrate. Then, a pressure of 4 kg/cm to 5 kg/cm was applied to the polarizing plate, thereby preparing a sample. The sample was stored at 60 ° C / 85% relative humidity for 500 hours, and then the sample was observed for bubbling or detachment. O: No bubbling or detachment occurred ∆: slight bubbling or detachment ×: severe bubbling or detachment

As shown in Table 2, it was confirmed that the K value of the adhesive film for a polarizing plate according to the present invention was within a predetermined range, thereby suppressing light leakage in the central portion of the panel and even at the end portion of the panel. Therefore, the adhesive film for a polarizing plate according to the present invention can suppress light leakage due to stress suppression for dimensional changes of the polarizing plate at high temperature and/or high humidity and due to optical compensation.

On the other hand, it was found that the adhesive films of Comparative Example 1 to Comparative Example 6 whose K values were outside the range of the present invention did not have an effect sufficient to cancel the birefringence or did not inhibit, as compared with the adhesive films of Examples 1 to 5. The stress, so the adhesive films of Comparative Example 1 to Comparative Example 6 had a light leakage problem.

It is to be understood that various modifications, changes, changes and equivalents may be made without departing from the spirit and scope of the invention.

1‧‧‧ polarizer
2‧‧‧First protective film
3‧‧‧Second protective film
4‧‧‧First Adhesive Film
5‧‧‧ Third protective film
6‧‧‧Second Adhesive Film
100, 200‧‧‧ polarizing plate
300‧‧‧ optical display
310‧‧‧LCD panel
320‧‧‧First polarizer
330‧‧‧Second polarizer
340‧‧‧Light source unit

1 is a cross-sectional view of a polarizing plate in accordance with an embodiment of the present invention. 2 is a cross-sectional view of a polarizing plate in accordance with another embodiment of the present invention. 3 is a cross-sectional view of an optical display in accordance with an embodiment of the present invention.

1‧‧‧ polarizer

2‧‧‧First protective film

3‧‧‧Second protective film

4‧‧‧First Adhesive Film

100‧‧‧Polar plate

Claims (13)

An adhesive film for a polarizing plate, wherein the K value calculated by Equation 1 is 0.2 to 0.5: Equation 1 K = ΔG' × ΔR ₀ where ΔG' is defined by Equation 2 and Δ R ₀ is defined by Equation 3, Equation 2 ΔG' = G1 - G2 where G1 is the storage modulus at 23 ° C and the unit is MPa, and G2 is the storage modulus at 85 ° C and the unit is MPa, G1 and G2 are conditions at which the strain is 5%, the normal force is 100 Newtons, and the angular frequency is 1 rad/sec while the temperature is raised from 0 °C to 100 °C at a rate of 10 °C/min. The temperature measurement test was performed using an advanced rheology measurement extension system to measure the adhesion of a 500 μm thick adhesive film for a polarizing plate, Equation 3 ΔR ₀ =R ₀₁ -R ₀₂ where R ₀₁ is at 85 ° C The retardation at 590 nm wavelength and the unit is nanometer, and R ₀₂ is the retardation at 590 nm wavelength at 23 ° C and the unit is nanometer, R ₀₁ and R ₀₂ are at a rate of 10 ° C / min from 0 °C is increased to 100 ° C while measuring a stress of 125 millinewtons / 15 mm on a 1 mm thick adhesive film for a polarizing plate, which is used for a polarizing plate. Forming a composition comprising a crosslinkable (meth)acrylic copolymer having a crosslinkable functional group, a non-crosslinkable (meth)acrylic copolymer having positive birefringence, and a curing agent, wherein the crosslinkable (meth)acrylic acid is copolymerized with 100 parts by weight of the crosslinkable (meth)acrylic copolymer and the non-crosslinkable (meth)acrylic copolymer The copolymer is present in an amount of from 60 parts by weight to 95 parts by weight, and the non-crosslinkable (meth)acrylic copolymer is present in an amount of from 5 parts by weight to 40 parts by weight. The adhesive film for a polarizing plate according to claim 1, wherein G1 of the adhesive film is 0.45 MPa to 1 MPa. The adhesive film for a polarizing plate according to claim 1, wherein the adhesive film has a G2 of 0.01 MPa to 0.3 MPa. An adhesive film for a polarizing plate according to claim 1, wherein the crosslinkable (meth)acrylic copolymer is a copolymer comprising a monomer mixture containing a crosslinkable functional group monomer, And the crosslinkable functional group-containing monomer is present in the monomer mixture in an amount of from 1% by weight to 20% by weight. An adhesive film for a polarizing plate according to claim 1, wherein the non-crosslinkable (meth)acrylic copolymer is a copolymer comprising a monomer mixture containing a crosslinkable functional group monomer. And the crosslinkable functional group-containing monomer is present in the monomer mixture in an amount of less than 1% by weight. An adhesive film for a polarizing plate according to claim 1, wherein each of the crosslinkable (meth)acrylic copolymer and the non-crosslinkable (meth)acrylic copolymer One has a weight average molecular weight of less than 1,000,000 grams per mole. The adhesive film for a polarizing plate according to claim 1, wherein the weight average molecular weight of the non-crosslinkable (meth)acrylic copolymer is 300,000 g / mol to less than 1,000,000 g / m. An adhesive film for a polarizing plate according to claim 1, wherein the crosslinkable (meth)acrylic copolymer is a copolymer comprising a monomer mixture: a hydroxyl group-containing (methyl) At least one of an acrylic monomer and a carboxylic acid group-containing (meth)acrylic monomer; and an alkyl group-containing (meth)acrylic monomer. An adhesive film for a polarizing plate according to claim 1, wherein the non-crosslinkable (meth)acrylic copolymer is a copolymer comprising a monomer mixture: an aromatic group-containing ( a methyl)acrylic monomer, an alkyl group-containing (meth)acrylic monomer, and a (meth)acrylic monomer represented by Formula 2: Wherein A is a C ₁ to C ₂₀ aliphatic hydrocarbon group; B is -O- or -S-; R ₁ is hydrogen or methyl; R ₂ is a C ₁ to C ₂₀ aliphatic hydrocarbon group; and n is an integer of 1 to 5 . The adhesive film for a polarizing plate according to claim 9, wherein the (meth)acrylic monomer represented by Formula 2 includes 2-(2-ethoxyethoxy) (meth)acrylate. Ethyl ester. The adhesive film for a polarizing plate according to claim 1, wherein the adhesive composition for the polarizing plate further comprises a decane coupling agent. a polarizing plate comprising: a polarizer; a first protective film formed on an upper surface of the polarizer; a second protective film formed on the lower surface of the polarizer; and an adhesive film for a polarizing plate according to any one of claims 1 to 11, wherein the second protective film is formed on the second protective film On the lower surface. An optical display comprising: a liquid crystal display panel; a first polarizing plate formed on an upper surface of the liquid crystal display panel; and a liquid crystal display panel and a light source unit to be disposed on a lower surface of the liquid crystal display panel And a second polarizing plate, wherein at least one of the first polarizing plate and the second polarizing plate is a polarizing plate according to claim 12 of the patent application.