KR20200077826A - A polarizer having adhesive - Google Patents

Abstract

The present application relates to an adhesive polarizing plate including a polarizer having a notch and an adhesive layer formed on at least one surface of the polarizer. The adhesive polarizing plate may mitigate light leakage from the notch.

Description

A polarizer having adhesive

The present application relates to an adhesive polarizing plate.

In a display in which a generally used square-shaped polarizing plate is applied, there is little light leakage because the shrinking force or stress of the polarizing plate is evenly spread over the entire polarizing plate. However, in recent years, a polarizing plate having a notch shape is used. In this type of polarizing plate, stress is concentrated in the notch portion of the polarizing plate, and thus light leakage occurs in the corresponding portion, thereby causing unevenness in the user's visual acuity for the display. There is a problem. Accordingly, there is a need for a technique capable of resolving light leakage due to the shape of the notch and user's visual defect.

One object of the present application is to provide an adhesive polarizing plate capable of solving the problem of light leakage of a polarizing plate having a notch portion.

The above and other other objects of the present application can be solved by the present application described in detail below.

In an example related to the present application, the present application relates to an adhesive polarizing plate. The adhesive polarizing plate includes a polarizer having a notch; And an adhesive layer formed on at least one surface of the polarizing plate.

In the present application, that a polarizer (or polarizer) has a notch means that a portion whose shape is rapidly changed is present in the polarizer (or polarizer). For example, when the shape of the rim of the polarizer (or polarizer) changes, the portion where the degree of change is more rapid than the surrounding may be referred to as a notch or notch portion of the polarizer (or polarizer). Further, in some cases, holes formed in the polarizer (or polarizer) may also be referred to as notches.

The notch can be observed, for example, in a smartphone or tablet PC with a large display, such as bezeless. Specifically, when most of the front part of the smartphone or tablet PC is used as a screen, the space for storing the front camera or sensors that must be located on the user's side of view becomes relatively insufficient, so the storage space of the camera or sensor In order to secure the polarizing plate or a display including the same, the operation of cutting the polarizing plate may be performed, and accordingly, a notch (part) may be formed in the polarizing plate or the display.

However, due to the stress concentrated on the notch, light leakage occurs in the notch of the polarizing plate, and the light leakage causes a display defect problem such as unevenness in user visibility. This application was developed to solve the above problems.

The adhesive polarizing plate according to an example of the present application includes a polarizer having a notch; And an adhesive layer formed on at least one surface of the polarizer. The shape of the adhesive layer and the polarizer may be the same or different.

In one example, in order to adhere or adhere to the polarizer, and to adhere or adhere the adhesive polarizer to another member, the shape of the adhesive layer may be the same as the shape of the polarizer having a notch. At this time, having the same shape is used to mean that the shape of the adhesive layer and the polarizer are similar.

When compared to the modulus at room temperature, the adhesive layer may have a lower degree of modulus at high temperature than the prior art. That is, the degree of modulus downward at high temperature may be greater than that of the prior art.

In the present application, "normal temperature" may mean a temperature in a state that is not particularly warmed or reduced, and may mean, for example, a temperature in the range of 23°C to 33°C, more specifically 30°C. In addition, in the present application, "high temperature" may mean a temperature within a range of 75 to 85°C, more specifically 80°C.

Specifically, the adhesive layer may have a modulus (M ₁ ) measured at room temperature of 60,000 Pa or more. When the modulus value at room temperature is less than the above range, there is a problem in that workability is poor because the so-called pressure-sensitive adhesive is missing in the manufacturing process of the adhesive polarizing plate as well as deteriorating durability. More specifically, the room temperature modulus (M ₁ ) of the adhesive layer may be 61,000 Pa, 62,000 Pa, 63,000 Pa, 64,000 Pa, 65,000 Pa, 66,000 Pa, 67,000 Pa, 68,000 Pa, 69,000 Pa, or 70,000 Pa or more. In addition, the upper limit of the room temperature modulus (M ₁ ) of the adhesive layer may be, for example, 90,000 Pa, 85,000 Pa, or 75,000 Pa or less. If the above range is satisfied, it may have appropriate durability at room temperature.

In the adhesive layer of the present application that satisfies the normal temperature modulus (M ₁ ) within the above range, the downward degree of the modulus measured at a high temperature may satisfy the following values.

For example, the adhesive layer may have a value in which the difference between the normal temperature modulus (M ₁ ) and the high temperature modulus (M ₂ ) is 15,000 Pa or more, and more specifically, exceeds 15,000 Pa.

Specifically, the modulus (M ₂ ) value of the adhesive layer may be 45,000 Pa or less, 44,000 Pa or less, 43,000 Pa or less, 42,000 Pa or less, 41,000 Pa or less, or 40,000 Pa or less. When the above values are satisfied, the stress applied in the vicinity of the notch can be sufficiently relieved. The lower limit of the high temperature modulus (M ₂ ) value may be, for example, 30,000 Pa. If the modulus value at high temperature is less than the lower limit, high temperature reliability is not good.

In one example, the ratio (M1/M2) of the modulus M1 and the modulus M2 may be 1.3 or more. When the ratio (M1/M2) is less than 1.3, it means that the downward of the high temperature modulus at high temperature is not sufficient, and thus the stress relaxation effect in the vicinity of the notch is not good. For example, the ratio (M1/M2) may be 1.4 or more, 1.5 or more, 1.6 or more, or 1.7 or more. The lower limit of the ratio may be, for example, 3.0 or less, 2.9 or less, 2.8 or less, 2.7 or less, 2.6 or less, 2.5 or less, 2.4 or less, 2.3 or less, 2.2 or less, 2.1 or less, or 2.0 or less.

In one example, the adhesive layer may satisfy a stress relaxation (%) value at room temperature of 35% or less. When the stress relaxation (%) value satisfies the above range, the pressure-sensitive adhesive layer can sufficiently relieve stress given near the notch at room temperature. The lower limit of the stress relaxation (%) value may be, for example, 10% or more, 15% or more, 20% or more, or 25% or more. The stress relaxation (%) value at room temperature can be measured as in the Examples below.

In one example, the adhesive layer may satisfy a stress relaxation (%) value at a high temperature of 35% or less. When the stress relaxation (%) value satisfies the above range, the pressure-sensitive adhesive layer can sufficiently relieve stress given near the notch at high temperature. The lower limit of the stress relaxation (%) value may be, for example, 10% or more, 15% or more, 20% or more, or 25% or more. The stress relaxation (%) value at high temperature can be measured as in the following examples.

If the properties of the adhesive polarizing plate can be satisfied, the adhesive layer component used for forming the adhesive layer is not particularly limited.

In one example, the adhesive layer may include a crosslinkable polymer. The crosslinkable polymer means a polymer having a crosslinkable functional group capable of forming a crosslinked structure in the adhesive layer. The crosslinkable functional group is a functional group provided on the side chain or terminal of the polymer, etc., and is at least a functional group capable of reacting with the functional group of the polyfunctional crosslinking agent described later.

In one example, the crosslinkable polymer can be a block copolymer. In the present application, the term "block copolymer" may refer to a copolymer including blocks of different polymerized monomers.

In one example, the block copolymer may include a first block having a glass transition temperature of 50°C or higher and a second block having a glass transition temperature of -10°C or lower. In the present application, the glass transition temperature of each block of the block copolymer may mean a glass transition temperature measured or calculated from a polymer formed only of monomers (monomers) included in the block.

Specifically, the glass transition temperature of the first block may be, for example, 60°C or higher, 65°C or higher, or 70°C or higher. The upper limit of the glass transition temperature of the first block is not particularly limited, and may be, for example, about 150 ℃ 140 ℃, 130 ℃ or 120 ℃.

Further, the glass transition temperature of the second block may be, for example, -20°C or less, -30°C or less, -35°C or less, or -40°C or less. The lower limit of the glass transition temperature of the second block is not particularly limited, and may be, for example, about -80 °C, -70 °C, -60 °C, -55 °C, or -50 °C.

The block copolymer comprising the first and second blocks having a glass transition temperature within the above range can form an appropriate fine phase separation structure in the pressure sensitive adhesive, and the pressure sensitive adhesive containing the phase separation structure has an appropriate level of cohesion and stress relaxation. It has excellent reliability, light leakage prevention properties and reworkability.

The molecular weight characteristic of the first block, that is, a hard block having a relatively high glass transition temperature may be adjusted in the following range.

For example, the number average molecular weight (Mn: Number Average Molecular Weight) of the first block may be adjusted within a range of 2,500 to 100,000. In the present application, "the number average molecular weight of the first block" may mean, for example, a number average molecular weight of a polymer produced by polymerizing only the monomers forming the first block. The number average molecular weight mentioned in this specification can be measured by a conventional method using, for example, GPC (Gel Permeation Chromatograph). In another example, the number average molecular weight of the first block may be 5,000 or more, 10,000 or more, 15,000 or more, 20,000 or more, 25,000 or more, or 30,000 or more. In addition, the upper limit of the number average molecular weight of the first block may be, for example, 80,000 or less, 75,000 or less, 70,000 or less, 65,000 or less, 60,000 or less, 55,000 or less, 50,000 or less, 45,000 or less, or 40,000 or less.

In one example, the molecular weight distribution (PDI; Mw/Mn) of the first block, that is, the ratio (Mw/Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) may satisfy within a range of 1.0 to 2.0. have. Specifically, the molecular weight distribution of the first block may be 1.1 or more, 1.15 or more, 1.2 or more, 1.25 or more, 1.3 or more, 1.35 or more, or 1.4 or more, and an upper limit of the molecular weight distribution of the first block is, for example, 1.8 or less, 1.75 or less, 1.70 or less, 1.65 or less, 1.60 or less, 1.55 or less, or 1.50 or less.

The molecular weight properties of the first block may be adjusted as described above to provide an adhesive composition or adhesive having excellent physical properties.

In one example, the block copolymer may have a number average molecular weight (Mn) of 10,000 to 300,000. In another example, the number average molecular weight of the block copolymer is 20,000 or more, 30,000 or more, 40,000 or more, 50,000 or more, 60,000 or more, 70,000 or more, 80,000 or more, 90,000 or more, 10,000 or more, 110,000 or more, 120,000 or more, 130,000 or more, 140,000 Or more than 150,000. And the upper limit may be, for example, 290,000 or less, 280,000 or less, 270,000 or less, 260,000 or less, 250,000 or less, 240,000 or less, 230,000 or less, 220,000 or less, 210,000 or less, or 200,000 or less.

In another example, the block copolymer may have a molecular weight distribution in the range of 1.5 to 3.5. Specifically, the molecular weight distribution of the block copolymer may be, for example, 1.6 or more, 1.7 or more, 1.8 or more, 1.9 or more, 2.0 or more, 2.1 or more, 2.2 or more, 2.3 or more, 2.4 or more, or 2.5 or more. In addition, the upper limit of the molecular weight distribution of the block copolymer may be, for example, 3.5 or less, 3.4 or less, 3.3 or less, 3.20 or less, 3.1 or less, or 3.0 or less.

When including a block copolymer having the molecular weight characteristics as described above, it is advantageous to secure excellent adhesion properties.

In one example, the crosslinkable polymer can include a crosslinkable functional group. The crosslinkable functional group may be, for example, a hydroxy group, a carboxyl group, an isocyanate group or a glycidyl group. When a crosslinkable functional group is included in the block copolymer, the crosslinkable functional group may be included in, for example, a block having a relatively low glass transition temperature, that is, a second block.

In one example, the crosslinkable functional group is not included in the first block, but may be included only in the second block. When the crosslinkable functional group is included in the second block having a relatively low glass transition temperature, it is possible to form a pressure-sensitive adhesive that exhibits appropriate cohesive strength and stress relaxation properties and thus maintains excellent physical properties such as durability, light leakage prevention properties, and reworkability. have.

The type of the monomers forming the first block and the second block in the block copolymer is not particularly limited as long as the glass transition temperature as described above is secured by the combination of each monomer.

The first block may include, for example, polymerization units derived from (meth)acrylic acid ester monomers. In the present specification, "a monomer is contained in a polymer or block as a polymerized unit" may mean that the monomer undergoes a polymerization reaction to form a skeleton of the polymer or block, for example, a main chain or a side chain. .

As the methacrylic acid ester monomer, for example, alkyl (meth)acrylate can be used. In consideration of cohesion, glass transition temperature, and adjustment of adhesion, an alkyl (meth)acrylate having an alkyl group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms is used. Can be used. In the above, the alkyl group may be linear, branched or cyclic. Such monomers include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth) Acrylate, sec-butyl (meth)acrylate, pentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-ethylbutyl (meth)acrylate, n-octyl (meth)acrylate, isobor Neil (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate or lauryl (meth)acrylate, etc. may be exemplified, and the glass transition temperature of one or more of the above is secured It can be selected and used as much as possible.

As a monomer forming the first block in consideration of the ease of adjusting the glass transition temperature, etc., among the monomers, a methacrylic acid ester monomer such as alkyl methacrylate, for example, 1 to 20 carbon atoms, 1 to 16 carbon atoms, carbon number Alkyl methacrylate having an alkyl group having 1 to 12, 1 to 8, or 1 to 4 carbon atoms can be used.

The second block may include, for example, 90 parts by weight to 99.9 parts by weight of a polymerization unit of an alkyl (meth)acrylate and 0.1 parts by weight to 10 parts by weight of a polymerization unit of a copolymerizable monomer having a crosslinkable functional group. In the present specification, the unit “parts by weight” may mean a ratio of weights between components. For example, the second block includes 90 parts by weight to 99.9 parts by weight of the polymerization unit of the alkyl (meth)acrylate and 0.1 part to 10 parts by weight of the polymerization unit of the copolymerizable monomer having a crosslinkable functional group. When the ratio (A:B) based on the weight of the alkyl (meth)acrylate (A) forming the polymerized unit and the copolymerizable monomer (B) having a crosslinkable functional group is 90 to 99.9: 0.1 to 10 Can mean In the range of the weight ratio, the physical properties of the pressure-sensitive adhesive, for example, adhesion and durability can be maintained excellent.

As the alkyl (meth)acrylate forming the second block, a glass transition temperature within the above-described range can be finally secured through copolymerization with the copolymerizable monomer among monomers that may be included in the first block. Any type of monomer can be selected and used. Although not particularly limited, the alkyl (meth)acrylate forming the second block in consideration of the ease of adjusting the glass transition temperature, etc., among the monomers described above, for example, 1 to 20 carbon atoms, 1 to 16 carbon atoms, An alkyl (meth)acrylate having an alkyl group having 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms can be used.

As a copolymerizable monomer having a crosslinkable functional group forming a second block, for example, it has a site that can be copolymerized with other monomers included in the block copolymer, such as alkyl (meth)acrylate, and is also crosslinkable. Compounds having a functional group can be used. In the manufacturing field of the adhesive, various copolymerizable monomers having such crosslinkable functional groups are known, and all of these monomers can be used in the polymer. For example, as a copolymerizable monomer having a hydroxy group, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxy Hydroxyalkyl (meth)acrylates such as hexyl (meth)acrylate or 8-hydroxyoctyl (meth)acrylate, or 2-hydroxyethylene glycol (meth)acrylate or 2-hydroxypropylene glycol (meth) Hydroxyalkylene glycol (meth)acrylates such as acrylates can be used, and copolymerizable monomers having a carboxyl group include (meth)acrylic acid, 2-(meth)acryloyloxy acetic acid, and 3-(meth) Acryloyloxy propyl acid, 4-(meth)acryloyloxy butyric acid, acrylic acid duplex, itaconic acid, maleic acid and maleic anhydride can be used. It is not limited thereto.

In addition, the first block and/or the second block may further include other optional comonomers, if necessary, for example, for control of glass transition temperature, etc., and the monomers may be included as polymerization units Can. Examples of the comonomer include (meth)acrylonitrile, (meth)acrylamide, N-methyl (meth)acrylamide, N-butoxy methyl (meth)acrylamide, N-vinyl pyrrolidone or N-vinyl capro Nitrogen-containing monomers such as lactam; Styrene-based monomers such as styrene or methyl styrene; Glycidyl group-containing monomers such as glycidyl (meth)acrylate; Or a carboxylic acid vinyl ester such as vinyl acetate, and the like, but is not limited thereto. These comonomers may be included in the polymer by selecting a suitable kind or two or more kinds as appropriate. Such a comonomer may be included in the block copolymer in a ratio of, for example, 20 parts by weight or less, or 0.1 parts by weight to 15 parts by weight based on the weight of other monomers in each block copolymer.

In the present application, the polymer may include an aromatic group so as to have an optical compensation function.

In one example, the block copolymer may include an aromatic group.

Specifically, the block copolymer has a site that can be copolymerized with other monomers included in the block copolymer, such as, for example, a carbon-to-carbon double bond, and may include units derived from a compound containing an aromatic group at the same time. . The type of the compound capable of providing an aromatic group may be, for example, styrene or a compound corresponding to Formula 1 below.

In one example, the compound containing the vinyl group and the aromatic group may be represented by the following formula (1).

[Formula 1]

In Formula 1, R1 is hydrogen or an alkyl group, R2 is an alkylene group or an alkylidene group, m is an integer from 0 to 5, X is a single bond, an oxygen atom or a sulfur atom, and Ar is an aryl group. In the context of X, a single bond means a case where a separate atom does not exist in a portion connected by X, and for example, R2 and Ar are directly connected.

In relation to Formula 1, an aryl group means a monovalent residue derived from a compound or a derivative thereof containing a structure in which benzene or two or more benzenes are condensed or bonded. The aryl group may be, for example, an aryl group having 6 to 22 carbon atoms, 6 to 16 carbon atoms, or 6 to 13 carbon atoms, for example, a phenyl group, a phenylethyl group, a phenylpropyl group, a benzyl group, a benzyloxy group, or a phenoxy group. , Tolyl group, xylyl group, phenylthio group, naphthyl group or naphthyloxy group.

In addition, m in Formula 1 may be, for example, 0 to 4, 0 to 3, 0 to 2, or 0 or 1.

As the compound of Formula 1, phenoxy ethyl (meth)acrylate, benzyl (meth)acrylate, 2-phenylthio-1-ethyl (meth)acrylate, 6-(4,6-dibromo-2- Isopropyl phenoxy)-1-hexyl (meth)acrylate, 6-(4,6-dibromo-2-sec-butyl phenoxy)-1-hexyl (meth) acrylate, 2,6-dibro Mo-4-nonylphenyl (meth)acrylate, 2,6-dibromo-4-dodecyl phenyl (meth)acrylate, 2-(1-naphthyloxy)-1-ethyl (meth)acrylate, 2-(2-naphthyloxy)-1-ethyl (meth)acrylate, 6-(1-naphthyloxy)-1-hexyl (meth)acrylate, 6-(2-naphthyloxy)-1- Hexyl (meth)acrylate, 8-(1-naphthyloxy)-1-octyl (meth)acrylate and 8-(2-naphthyloxy)-1-octyl (meth)acrylate, etc. can be exemplified. .

In one example, when an aromatic group is included in the second block, the aromatic group is not included in the first block, and may be included only in the second block. When the aromatic group is included in the second block, the aromatic group is properly oriented in a constant direction and an adhesive having excellent light leakage prevention properties can be formed. In particular, when the adhesive is exposed to high temperature or high temperature and high humidity conditions, optical compensation is performed by the aromatic group to reduce light leakage.

When the aromatic group is included in the second block, the second block is 80 to 95 parts by weight of a (meth)acrylic acid ester monomer, 5 to 15 parts by weight of an aromatic group-containing monomer, and 0.1 to 10 copolymerizable monomers providing a crosslinkable functional group. It may include units derived from parts by weight. In one example, the content of the aromatic group-containing monomer may be 6 parts by weight or more, 7 parts by weight or more, 8 parts by weight or more, 9 parts by weight or more, or 10 parts by weight or more.

The block copolymer may include 1 part by weight to 30 parts by weight of the first block, and 70 parts by weight to 99 parts by weight of the second block. The ratio of the weight between the first block and the second block is not particularly limited, but it is possible to provide a pressure-sensitive adhesive composition and pressure-sensitive adhesive having excellent physical properties by adjusting the weight-to-block ratio as described above. In another example, the block copolymer within the above range, the first block 2 parts by weight or more, 3 parts by weight or more, 4 parts by weight or more, 5 parts by weight or more, 6 parts by weight or more, 7 parts by weight or more, 8 parts by weight Or more, 9 parts by weight or more, or 10 parts by weight or more. In another example, the block copolymer within the above range, the first block 20 parts by weight or less, 19 parts by weight or less, 18 parts by weight or less, 17 parts by weight or less, 16 parts by weight or less, 15 parts by weight or less, 14 parts by weight Parts, 13 parts by weight or less, 12 parts by weight or less, or 11 parts by weight or less.

In one example, the block copolymer may be a diblock copolymer composed of the first and second blocks, that is, a block copolymer including only two blocks of the first and second blocks. By using the diblock copolymer, the durability of the pressure-sensitive adhesive, stress relaxation and reworkability, etc. can be better maintained.

The method for producing the block copolymer is not particularly limited and can be produced in a conventional manner. The block copolymer may be polymerized by, for example, LRP (Living Radical Polymerization), for example, an organic rare earth metal complex may be used as a polymerization initiator, or an organic alkali metal compound may be used as a polymerization initiator to form an alkali metal or alkaline earth metal. Anionic polymerization synthesized in the presence of an inorganic acid salt or the like, anionic polymerization method synthesized in the presence of an organoaluminum compound using an organic alkali metal compound as a polymerization initiator, atomic transfer radical polymerization using an atomic transfer radical polymerization agent as a polymerization control agent Activators Regenerated by Electron Transfer (ARGET) Atomic Transfer Radical Polymerization (ATRP), ICAR (Initiators) using an atomic transfer radical polymerization agent as a polymerization control agent, but performing polymerization under an organic or inorganic reducing agent that generates electrons for continuous activator regeneration, atomic transfer radical polymerization (ATRP), inorganic reducing agent, reversible addition-cracked chain transfer using a reversible chain transfer agent (RAFT), or a method using an organic tellurium compound as an initiator. , Among these methods, an appropriate method can be selected and applied.

In one example, the pressure-sensitive adhesive composition may include at least one selected from the group consisting of epoxy compounds and aziridine compounds.

The epoxy or aziridine compound may be a monofunctional or polyfunctional compound. For example, a monofunctional epoxy compound means a compound having one glycidyl group, and a polyfunctional epoxy compound can mean a compound containing at least 2, for example, 2 to 5 glycidyl groups. have.

The aziridine compound means an aziridine or aziridine derivative, and the multifunctional aziridine compound means a compound containing two, for example, two to five aziridine rings or aziridine derivative rings. Can. Such a compound can greatly contribute to improvement of adhesion between an optical film such as a polarizing plate, particularly an optical film having a carboxyl group on the surface, and an adhesive layer. In the above, the carboxyl group on the surface of the optical film may be a material that the optical film itself contains, or may be artificially introduced by a method such as corona treatment.

In one example, the epoxy compound, ethylene glycol diglycidyl ether, triglycidyl ether, trimethylolpropane triglycidyl ether, N,N,N',N'-tetraglycidyl ethylenediamine or glycerin Diglycidyl ether and the like, or a compound of two or more kinds can be used. As the aziridine compound, for example, N,N'-toluene-2,4-bis(1-aziridinecarboxamide), N ,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), triethylenemelamine, bisisopropaloyl-1-(2-methylaziridine) or tri-1-aziridi Neil phosphine oxide, and the like may be selected from one or more species, but is not limited to those listed above.

The epoxy compound or the aziridine compound may be included in 0.001 part to 10 parts by weight, 0.01 part to 5 parts by weight, or 0.025 part to 2.5 parts by weight based on 100 parts by weight of the adhesive copolymer. However, this ratio is not particularly limited, and can be appropriately adjusted, for example, taking into account the amount of carboxyl groups present on the surface of the optical film or the like.

The pressure-sensitive adhesive composition may further include a crosslinking agent. As the crosslinking agent, a compound having at least two functional groups capable of reacting with the crosslinkable functional group of the block copolymer, for example, about 2 to 5, may be used. Therefore, the type of the polyfunctional crosslinking agent may be selected in consideration of the type of the crosslinkable functional group present in the block copolymer, for example, a polyfunctional isocyanate compound, i.e., two or more isocyanate groups, for example, 2 to A compound having about 5 can be used.

As the isocyanate compound, for example, diisocyanate compounds such as tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isoboron diisocyanate, tetramethylxylene diisocyanate, or naphthalene diisocyanate, or the above A compound obtained by reacting a diisocyanate compound with a polyol can be used, and as the polyol, for example, trimethylol propane or the like can be used.

The multifunctional crosslinking agent may be included in the pressure-sensitive adhesive composition in an amount of 0.01 to 10 parts by weight, 0.01 to 5 parts by weight, or 0.01 to 1 part by weight based on 100 parts by weight of the copolymer. The ratio may be appropriately changed in consideration of the desired degree of crosslinking, cohesion, adhesion, and durability.

The pressure-sensitive adhesive composition may further include a silane coupling agent. As the silane coupling agent, for example, a silane coupling agent having a beta-cyano group or acetoacetyl group can be used. Such a silane coupling agent, for example, the pressure-sensitive adhesive formed by a copolymer having a low molecular weight can exhibit excellent adhesion and adhesion stability, and also can maintain excellent durability and durability under heat and moisture resistance conditions. .

As a silane coupling agent having a beta-cyano group or acetoacetyl group, for example, a compound represented by the following formula 2 or 3 can be used.

[Formula 2]

(R ₁ ) _n Si(R ₂ ) _(4-n)

[Formula 2]

(R ₃ ) _n Si(R ₂ ) _(4-n)

In Formula 2 or 3, R1 is a beta-cyanoacetyl group or a beta-cyanoacetylalkyl group, R3 is an acetoacetyl group or acetoacetylalkyl group, R2 is an alkoxy group, and n is a number from 1 to 3 .

In Formula 2 or 3, the alkyl group may be an alkyl group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, and the alkyl group may be linear, branched or cyclic have.

In Formula 2 or 3, the alkoxy group may be an alkoxy group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, and the alkoxy group may be linear, branched or cyclic have.

In Formula 2 or 3, n may be, for example, 1 to 3, 1 to 2, or 1.

As the compound of Formula 2 or 3, for example, acetoacetylpropyl trimethoxy silane, acetoacetylpropyl triethoxy silane, beta-cyanoacetylpropyl trimethoxy silane or beta-cyanoacetylpropyl triethoxy silane, etc. It may be illustrated, but is not limited thereto.

In the adhesive composition, the silane coupling agent may be included in an amount of 0.01 to 5 parts by weight or 0.01 to 1 part by weight based on 100 parts by weight of the block copolymer, and can effectively impart desired physical properties to the adhesive within this range.

The pressure-sensitive adhesive composition may further include a tackifier as needed. Examples of the tackifier include hydrocarbon resins or hydrogenated products thereof, rosin resins or hydrogenated products thereof, rosin ester resins or hydrogenated products thereof, terpene resins or hydrogenated products thereof, terpene phenol resins or hydrogenated products thereof, polymerized rosin resins, or Polymerized rosin ester resins, such as one or a mixture of two or more may be used, but is not limited thereto. The tackifier may be included in the pressure-sensitive adhesive composition in an amount of 100 parts by weight or less based on 100 parts by weight of the block copolymer.

The pressure-sensitive adhesive composition may also further include, if necessary, one or more additives selected from the group consisting of curing agents, ultraviolet stabilizers, antioxidants, colorants, reinforcing agents, fillers, antifoaming agents, surfactants and plasticizers.

In the present application, the type of the polarizer attached to one surface of the adhesive layer is not particularly limited. At this time, the polarizer refers to a film, sheet, or device itself that exhibits a polarization function, and the polarizer refers to an optical device including other elements together with the polarizer.

The type of the polarizer included in the polarizing plate is not particularly limited, and for example, a general type known in the field, such as a polyvinyl alcohol-based polarizer, can be employed without limitation.

A polarizer is a functional film that can extract only light that vibrates in one direction from incident light while vibrating in various directions. Such a polarizer may be, for example, a form in which a dichroic dye is adsorbed and oriented in a polyvinyl alcohol-based resin film. The polyvinyl alcohol-based resin constituting the polarizer can be obtained, for example, by gelling a polyvinyl acetate-based resin. In this case, the polyvinyl acetate-based resin that can be used may include a copolymer of vinyl acetate and other monomers copolymerizable therewith, as well as a homopolymer of vinyl acetate. Examples of monomers copolymerizable with vinyl acetate include, but are not limited to, unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having ammonium groups, or mixtures of two or more thereof. no. The gelation degree of the polyvinyl alcohol-based resin is usually about 85 mol% to about 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be further modified, for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. In addition, the degree of polymerization of the polyvinyl alcohol-based resin may be generally about 1,000 to 10,000 or about 1,500 to 5,000.

The polarizer stretches (ex. uniaxially stretches) the polyvinyl alcohol-based resin film as described above, dyes the polyvinyl alcohol-based resin film with a dichroic dye, adsorbs the dichroic dye, and adsorbs the dichroic dye. The prepared polyvinyl alcohol-based resin film may be prepared through a process of treating with a boric acid aqueous solution and a process of washing with water after treating with a boric acid aqueous solution. As the dichroic dye, iodine or dichroic organic dye may be used.

The polarizing plate may further include a protective film attached to one side or both sides of the polarizer, and in this case, the pressure-sensitive adhesive layer may be formed on one side of the protective film. The type of the protective film is not particularly limited, for example, cellulose-based films such as TAC (Triacetyl cellulose); Polyester film such as polycarbonate film or PET (poly(ethylene terephthalet)); Polyethersulfone-based films; Or a polyethylene film, a polypropylene film or a polyolefin-based film produced using a cyclo-based (for example, COP) or a resin having an norbornene structure or an ethylene-propylene copolymer, etc. Can be used, more preferably, a cellulose-based film such as TAC can be used.

For example, in the structure in which the protective film is present as described above, a carboxyl group may be present on the surface of the protective film, and an adhesive layer may be attached to the surface. That is, in the polarizing plate, between the polarizer and the pressure-sensitive adhesive layer, a polarizer protective film in which a carboxyl group is present on the surface exists, and the pressure-sensitive adhesive layer may be attached to the surface of the protective film in which the carboxyl group is present.

As described above, such a carboxyl group may include a protective film itself or introduced by corona treatment or the like due to the characteristics of the material. Accordingly, in the polarizing plate, a polarizer protective film having a corona-treated layer on the surface exists between the polarizer and the adhesive layer, and the adhesive layer may be attached to the corona-treated layer. The method of forming the corona treatment layer on the protective film is not particularly limited.

The polarizing plate may further include at least one functional layer selected from the group consisting of a protective layer, a reflective layer, an anti-glare layer, a retardation plate, a wide viewing angle compensation film and a brightness enhancing film.

In the present application, the method of forming the pressure-sensitive adhesive layer on the polarizing plate or the optical member is not particularly limited, and for example, a method of directly coating and curing the pressure-sensitive adhesive composition to implement a crosslinked structure, or release treatment of the release film After coating and curing the pressure-sensitive adhesive composition on the surface to form a cross-linked structure, a method of transferring it may be used.

The method of coating the pressure-sensitive adhesive composition is not particularly limited, and for example, a method of applying the pressure-sensitive adhesive composition by a conventional means such as a bar coater may be used.

It is preferable from the viewpoint of performing a uniform coating process that the multifunctional crosslinking agent included in the pressure-sensitive adhesive composition in the coating process is controlled so that the crosslinking reaction of the functional group does not proceed, and through this, the crosslinking agent crosslinks in the curing and aging process after the coating operation. It is possible to improve the cohesive force of the pressure-sensitive adhesive by forming a structure, and improve the adhesion properties and cuttability.

In addition, the coating process is preferably performed after sufficiently removing bubble-inducing components such as volatile components or reaction residues in the pressure-sensitive adhesive composition, and accordingly, the crosslink density or molecular weight of the pressure-sensitive adhesive is too low, resulting in poor elastic modulus and high temperature. Bubbles existing between the glass plate and the adhesive layer become large, thereby preventing a problem of forming a scattering body therein.

The present application also relates to a display device, for example an LCD device. The display device may include, for example, the above-mentioned optical member or polarizing plate. When the display device is an LCD, the device may include a liquid crystal panel and the polarizing plate or optical member attached to one or both surfaces of the liquid crystal panel. The polarizing plate or the optical member may be attached to the liquid crystal panel by the above-described pressure-sensitive adhesive. Examples of the liquid crystal panel applied to the LCD include, for example, a passive matrix type panel such as a twisted nematic (TN) type, a super twisted nematic (STN) type, a ferrolectic (F) type, or a polymer dispersed (PD) type; An active matrix type panel such as a two-terminal or three-terminal type; All well-known panels, such as an In-plane Switching (IPS) panel and a Vertical Alignment (VA) panel, can be applied.

Other configurations of the display device, for example, types of upper and lower substrates such as color filter substrates or array substrates in LCDs are not particularly limited, and configurations known in the field can be employed without limitation.

According to an example of the present application, light leakage of the polarizing plate having the notch may be alleviated.

1 is an image photographed to confirm the degree of light leakage in Examples and Comparative Examples.

Hereinafter, the present application will be described through examples and comparative examples according to the present application. However, the scope of the present application is not limited by the following examples.

<Comparison of characteristics and light leakage>

Comparison of the properties of the examples and comparative examples was made in the following manner. The measured results are shown in Table 2 below.

* Modulus (Pa) : Using TA Instuments' Ares G2, 5% strain, 1 rad/s Angular frequency and temperature (30 ℃, 80 ℃), adhesive The storage modulus was measured.

The stress relaxation property was determined for a given temperature (30 ℃ and 80 ℃), respectively, using the same device used in the above-mentioned modulus measured: - the stress relaxation property (stress realxtion,%). Specifically, under 50% strain conditions, the stress at 1 second and the stress at 180 seconds are measured, and the stress at 1 second to the stress at 180 seconds is measured. Was recorded as a percentage (%).

* Light leakage : The polarizing plates prepared in the following Examples and Comparative Examples were laminated with glass, placed on one surface of the backlight, and then, except for the polarizing plates, covered with a black plate or cloth to check the light leakage. The results are shown in FIG. 1.

* Molecular weight: The number average molecular weight (Mn) and molecular weight distribution (PDI) of the block or block copolymer were measured using GPC (Gel Permeation Chromatograph), and the GPC measurement conditions are as follows. For the production of the calibration curve, measurement results were converted using standard polystyrene (Aglient system (manufactured)).

<GPC measurement conditions>

Meter: Aglient GPC (Aglient 1200 series, U.S.)

Column: 2 PL Mixed B connections

Column temperature: 40℃

Eluent: THF (Tetrahydrofuran)

Flow rate: 1.0 mL/min

Concentration: ~1mg/mL (100μl injection)

* Glass transition temperature: The glass transition temperature (T _g ) of each block of the copolymer or block copolymer was calculated according to Equation A below.

[Formula A]

1/Tg=∑Wn/Tn

In the above formula, Wn is a weight fraction of a block copolymer or a monomer applied to each block of the copolymer, and Tn represents a glass transition temperature when each monomer forms a homopolymer. In other words, the right side in Equation A is the result of summing up the calculated value after calculating the weight fraction (Wn/Tn) divided by the glass transition temperature shown when the monomer forms a homopolymer by the weight fraction of the monomer used. to be.

<Examples and Comparative Examples>

Example

(1) Preparation of adhesive: 0.1 g of EBiB (ethyl 2-bromoisobutyrate) and 14.2 g of methyl methacrylate (MMA) were mixed with 6.2 g of ethyl acetate (EAc). The flask containing the mixture was sealed with a rubber film, nitrogen purged and stirred at about 25° C. for about 30 minutes, and dissolved oxygen was removed through bubbling. Thereafter, 0.002 g of CuBr2, 0.005 g of tris(2-pyridylmethyl)amine (TPMA) and 0.017 g of V-65 (2,2'-azobis(2,4-dimethyl valeronitrile)) were added to the deoxygenated mixture. Then, the reaction was initiated by immersion in a reaction tank at about 67°C (polymerization of the first block). At a time when the conversion rate of methyl methacrylate is about 75%, 140 g of butyl acrylate (BA) previously bubbled with nitrogen, 0.8 g of hydroxybutyl acrylate (HBA), 15.5 g of phenoxy ethyl acrylate and ethyl A mixture of 250 g acetate (EAc) was added in the presence of nitrogen. Then, 0.006 g of CuBr2, 0.012 g of TPMA, and 0.05 g of V-65 were added to the reaction flask, and chain extention reaction was performed (polymerization of the second block). When the conversion rate of the monomer (BA) reached 80% or more, a block copolymer (A1) was prepared by exposing the reaction mixture to oxygen and diluting it in a suitable solvent to terminate the reaction (V-65 in the above process has a half life of In consideration of the above, it was added by dividing appropriately until the end of the reaction). The composition of the block copolymer is shown in Table 1 below.

Subsequently, 0.1 part by weight of a crosslinking agent (Coronate L, manufactured by Japan NPU), 0.05 part by weight of an epoxy compound (T-746L, Sokensa (product)), 0.1 part of DBTDL (Dibutyltin dilaurate) with respect to 100 parts by weight of the prepared block copolymer 0.2 parts by weight of a silane coupling agent (M812, manufactured by LG Chemicals) having a part and a β-cyanoacetyl group was mixed, and ethyl acetate was blended as a solvent to adjust the coating solid content to about 25% by weight to prepare a coating solution (adhesive composition). .

(2) Preparation of a polarizing plate and an adhesive type product: A molded PET (poly(ethylene terephthalate)) (MRF-38, manufactured by Mitsubishi Co., Ltd.) having a thickness of 38 μm molded to release the prepared coating solution to a thickness of about 23 μm after drying. The release surface was coated and kept in an oven at 110° C. for about 3 minutes. After the drying, a pressure-sensitive adhesive was laminated on one surface of a cyclo-olefin polymer (COP) film of a polarizing plate (a PVA-based polarizing plate having a laminated structure of TAC (thickness 40 µm)/PVA polarizer/COP (thickness 30 µm)). Then, a WV (Wide View) liquid crystal layer (a commercial product having a thickness of 1 μm) was attached to the adhesive to prepare an adhesive product. At this time, it was cut to have a notch of the form shown in FIG.

[Table 1] Construction of block copolymer used in Example 1

Comparative example One

An adhesive composition (coating solution), a polarizing plate, and an adhesive product were prepared in the same manner as in Example 1, except that a copolymer having a different composition was used as follows.

Specifically, nitrogen gas is refluxed, 64 parts by weight of n-butyl acrylate (n-BA), 20 parts by weight of methyl acrylate MA, and benzyl acrylate (BzA) in a 1L reactor equipped with a cooling device to facilitate temperature control. A monomer mixture containing 15 parts by weight, and 1 part by weight of acrylic acid (AA) was administered. Subsequently, 120 parts by weight of ethyl acetate (EAc) was added as a solvent, and nitrogen gas was purged for 60 minutes to remove oxygen. Then, the temperature was maintained at 60°C, and 0.03 parts by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator, followed by reaction for 8 hours. After the reaction, it was diluted with ethyl acetate (EAc) to prepare an acrylic random copolymer having a solid content concentration of 15% by weight, a weight average molecular weight of 1.5 million, and a molecular weight distribution of 5.0.

Comparative example 2

As described below, a polarizing plate and an adhesive product were prepared in the same manner as in Example 1, except that a coating solution (adhesive composition) was prepared.

The nitrogen gas is refluxed, and a monomer mixture containing 99 parts by weight of n-butyl acrylate (n-BA) and 1.0 part by weight of hydroxyethyl methacrylate (HEMA) was added to a 1 L reactor equipped with a cooling device to facilitate temperature control. Was administered. Subsequently, 120 parts by weight of ethyl acetate (EAc) was added as a solvent, and nitrogen gas was purged for 60 minutes to remove oxygen. Then, the temperature was maintained at 60°C, and 0.03 parts by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator, followed by reaction for 8 hours. After the reaction, it was diluted with ethyl acetate (EAc) to prepare an acrylic random copolymer having a solid content concentration of 15% by weight, a weight average molecular weight of 1.6 million, and a molecular weight distribution of 4.9.

15 parts by weight of a trifunctional urethane acrylate (isocyanate-modified urethane acrylate, a reaction product of isocyanate and pentaerythritol triacrylate), trifunctional urethane acrylate (tris) (Meth)acryloxy ethyl isocyanurate) 5 parts by weight, XDI-based isocyanate curing agent (Mitsui Takeda, D110N, Japan) 1.0 parts by weight, lauryl peroxide (LPO) 2.0 parts by weight, hydroxy cyclohexylphenyl ketone (Swiss Ciba) Specialty chemicals) 0.5 parts by weight and β-cyanoacetyl-based silane coupling agent (M812, manufactured by LG Chemical) 0.1 parts by weight were mixed to prepare a coating solution (adhesive composition) by adjusting the solid content concentration of the coating solution to 15%.

Comparative example 3

An adhesive composition (coating solution), a polarizing plate, and an adhesive product were prepared in the same manner as in Example 1, except that a copolymer having a different composition was used as follows.

Specifically, nitrogen gas is refluxed, 79 parts by weight of n-butyl acrylate (n-BA), 20 parts by weight of methyl acrylate benzyl acrylate (BzA) in a 1L reactor equipped with a cooling device to facilitate temperature control, and A monomer mixture containing 1 part by weight of hydroxybutyl acrylate (HBA) was administered. Subsequently, 120 parts by weight of ethyl acetate (EAc) was added as a solvent, and nitrogen gas was purged for 60 minutes to remove oxygen. Then, the temperature was maintained at 60°C, and 0.03 parts by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator, followed by reaction for 8 hours. After the reaction, it was diluted with ethyl acetate (EAc) to prepare an acrylic random copolymer having a solid content concentration of 15% by weight, a weight average molecular weight of 1.5 million, and a molecular weight distribution of 7.0.

[Table 2]

Claims (16)

A polarizer having a notch; And an adhesive layer formed on at least one surface of the polarizer,
The adhesive layer has a modulus (M ₁ ) measured in the range of 23 to 33° C. is 60,000 Pa or more,
The adhesive polarizing plate having a difference value between the modulus (M ₁ ) and the modulus (M ₂ ) measured in the range of 75 to 85°C exceeds 15,000 Pa. The method of claim 1, wherein the adhesive layer has a modulus pressure sensitive adhesive-type polarizing plate (M ₁₎ is satisfied, and satisfies that the modulus (M ₂₎ 30,000 to 45,000 Pa range of 60,000 to 90,000 Pa range. The method of claim 1, wherein the modulus (M ₁₎ and the ratio (M ₁ / M ₂₎ adhesive-type polarizing plate is not less than 1.3 of the modulus (M _2). The adhesive polarizing plate of claim 1, wherein the adhesive layer has a stress relaxation (%) value in the range of 23 to 33° C. that satisfies 35% or less. The adhesive polarizing plate of claim 1, wherein the adhesive layer has a stress relaxation (%) value in the range of 75 to 85° C. that is 35% or less. The adhesive of claim 1, wherein the adhesive layer comprises a crosslinkable polymer, and the crosslinkable polymer has a unit derived from a (meth)acrylic acid ester monomer, a copolymerizable monomer providing a crosslinkable functional group, and an aromatic group-containing monomer. Type polarizer. According to claim 6, The adhesive layer is a first block having a glass transition temperature of 50 ℃ or more; And a block copolymer comprising a second block having a glass transition temperature of -10°C or less. 8. The adhesive flat tube according to claim 7, wherein the first block comprises a unit derived from a (meth)acrylic acid ester monomer. The method according to claim 7, wherein the second block is derived from 80 to 95 parts by weight of a (meth)acrylic acid ester monomer, 5 to 15 parts by weight of an aromatic group-containing monomer, and 0.1 to 10 parts by weight of a copolymerizable monomer that provides a crosslinkable functional group. Adhesive polarizing plate comprising a unit. The adhesive polarizing plate of claim 9, wherein the crosslinkable functional group is a hydroxy group, a carboxyl group, an isocyanate group, or a glycidyl group. The adhesive polarizing plate of claim 8, wherein the first block has a number average molecular weight in the range of 2,500 to 100,000. The adhesive polarizing plate of claim 8, wherein the first block has a molecular weight distribution within a range of 1.0 to 2.0. 8. The adhesive polarizing plate of claim 7, wherein the block copolymer has a number average molecular weight in the range of 10,000 to 300,000. The adhesive polarizing plate of claim 7, wherein the block copolymer has a molecular weight distribution of 1.5 to 3.5. According to claim 7, The first block 1 part by weight to 30 parts by weight; And 70 parts by weight to 99 parts by weight of the second block. The adhesive polarizing plate of claim 6, wherein the adhesive layer further comprises a crosslinking agent.

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