KR20200134698A - Optical laminate and display device - Google Patents

Abstract

The present application relates to an adhesive optical laminate and a display device including the same. According to the present application, a build-up characteristic of adhesive force and a light leakage suppression characteristic can be improved. The optical laminate includes an optical film and an adhesive layer having a block copolymer.

Description

Optical laminate and display device including the same

The present application relates to an optical laminate and a display device including the same.

A liquid crystal display device (hereinafter referred to as "LCD") typically includes a liquid crystal panel and an optical film including a liquid crystal component injected between two transparent substrates. Examples of the optical film include a polarizing film, a retardation film, or a brightness improving film. A pressure-sensitive adhesive for an optical film may be used to laminate these optical films to each other or to attach the optical film to an adherend such as a liquid crystal panel.

Since the materials forming each of the aforementioned optical films have different molecular structures or compositions from each other, these optical films also have different physical properties from each other. For example, films using a material having a one-way molecular arrangement under high temperature and/or high temperature and high humidity conditions lack dimensional stability due to shrinkage or expansion. Specifically, when a polarizing plate and other optical members such as the above optical film are fixed by an adhesive, and these laminates are placed in high temperature and/or high temperature and high humidity conditions, contraction or expansion of the polarizing plate occurs, and thus the adhesive Occurs. Such excitation increases birefringence and light leakage due to the stress concentrated in the polarizing plate. Therefore, the adhesive layer used in the optical film needs to be designed so that it does not lift from the optical film by having a fast build-up characteristic of adhesive force.

On the other hand, in order to minimize light leakage, optical compensation is required to control the negative birefringence of the adhesive caused by residual stress to positive birefringence.

For example, Prior Document 1 (Korean Patent Publication No. 10-2003-0069461) incorporates 0.01 to 40 parts by weight of a low molecular weight substance exhibiting positive birefringence under residual stress into the acrylic adhesive layer. We propose a technique to correct the birefringence of. However, due to the use of a low molecular weight material, the modulus of the pressure-sensitive adhesive is lowered, so that there is a problem of cutting properties when working with a polarizing plate, and during long-term storage, there is a problem that the low molecular weight material moves to the interface and phase-separates from the acrylic pressure-sensitive adhesive as the main component. In addition, due to the plasticizing effect of the low molecular weight body, the Mc (average molecular weight between cross-linking points) in the cross-linked structure substantially increases, resulting in a smaller residual stress, resulting in less orientation of the low molecular weight body. A large amount of low molecular weight material is required.

Prior Document 2 (Korean Patent Publication No. 2004-0030597) describes a method of improving plasticizer resistance of an adhesive layer by introducing an acrylic monomer containing an aromatic group in a side chain. In addition, Prior Document 3 (Korean Patent Publication No. 2002-0044070) and Prior Document 4 (No. 2003-0004119) describe a method of adjusting the refractive index of the pressure-sensitive adhesive layer by introducing an acrylic monomer containing an aromatic group in the side chain. Are doing.

However, the above method requires a large amount of aromatic-containing acrylic monomer, and there is a side effect of greatly increasing the adhesive strength of the pressure-sensitive adhesive by the large amount of aromatic-containing acrylic monomer, which adversely affects re-peelability, which is the main function of the pressure-sensitive adhesive for a polarizing plate. Therefore, it is necessary to minimize the amount of the acrylic monomer having an aromatic group and to allow the pressure-sensitive adhesive to effectively exhibit positive birefringence under residual stress.

An object of the present application is to provide an adhesive optical laminate and a display device.

Another object of the present application is to provide an adhesive optical laminate and a display device in which adhesive force can be quickly built up and lift of the adhesive is suppressed.

Another object of the present application is to provide an adhesive optical laminate and a display device in which light leakage is suppressed.

All of the above and 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 optical laminate. The pressure-sensitive adhesive optical laminate having the configuration described below may not only have light leakage stability because the pressure-sensitive adhesive effectively has positive birefringence under residual stress, but also can prevent lifting of the pressure-sensitive adhesive layer because the build-up property of the adhesive force is fast.

The optical laminate includes an optical film and an adhesive layer.

In one example, as the optical film, a polarizing plate, a polarizer, a retardation film, a brightness enhancing film, an anti-glare film, a wide viewing angle compensation film, etc., or a laminate in which two or more of the above are laminated may be exemplified. In the present application, the terms'polarizer' and'polarizing plate' refer to objects that are distinguished from each other. That is, the polarizer refers to a film, sheet, or device itself exhibiting a polarizing function, and the polarizing plate refers to an optical device including other elements together with the polarizer. Other elements that may be included in the optical element together with the polarizer may include a polarizer protective film or a retardation layer, but are not limited thereto.

In one example, the optical film used for the adhesive-type optical laminate may be a polarizer.

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

The polarizer is a functional film capable of extracting only light vibrating in one direction from incident light while vibrating in various directions. Such a polarizer may be, for example, in a form in which a dichroic dye is adsorbed and oriented on 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 homopolymer of vinyl acetate, as well as a copolymer of vinyl acetate and other monomers copolymerizable therewith. Examples of the monomers copolymerizable with vinyl acetate may include one or more mixtures of unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids and acrylamides having an ammonium group, but are limited thereto. no. The degree of gelation of the polyvinyl alcohol-based resin may be generally about 85 mol% to 100 mol%, and 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 is a process of stretching a polyvinyl alcohol-based resin film as described above (ex.uniaxial stretching), a process of dyeing a polyvinyl alcohol-based resin film with a dichroic dye and adsorbing the dichroic dye, and the dichroic dye is adsorbed. The polyvinyl alcohol-based resin film can be prepared through a process of treating the resulting polyvinyl alcohol-based resin film with an aqueous boric acid solution and a process of washing with water after treatment with an aqueous boric acid solution. In the above, as the dichroic dye, iodine or a dichroic organic dye may be used.

In addition to the polarizer, the polarizing plate may include a protective film and/or an optical functional film.

In one example, the polarizing plate may include a protective film attached to one or both surfaces of the polarizer, and in this case, the adhesive layer of the configuration described above may be formed on one or both surfaces of the protective film. The type of the protective film is not particularly limited. For example, the protective film may be a glass substrate, or may be a substrate containing a polymer component. For example, a cellulose-based film such as TAC (Triacetyl cellulose); Polyester-based films such as polycarbonate films or PET (poly(ethylene terephthalet)); Polyethersulfone film; Alternatively, a film having a single or two or more layered structure, such as a polyethylene film, a polypropylene film, or a polyolefin-based film prepared using a resin having a cyclo-based or norbornene structure, or an ethylene-propylene copolymer, may be used as the protective film. The protective film may have two or more stacked structures.

In one example, the polarizing plate may further include one or more optical functional films selected from the group consisting of a reflective film, an anti-glare film, a retardation film, a wide viewing angle compensation film, and a brightness enhancing film. The optical functional film may have two or more stacked structures.

In one example, the polarizing plate may include at least one wide viewing angle compensation film selected from ±A film, ±B film, and ±C film. In the present application,'A film' refers to a film that satisfies the refractive index of the film nx ≠ny = nz. In this case, a case of nx> ny is referred to as a +A film, and a case of nx <ny is referred to as a -A film. . The'B film' refers to a film whose refractive index satisfies nx ≠ny ≠nz, where nx> ny> nz is referred to as -B film, and nz> nx> ny is referred to as +B film. The'C film' refers to a film in which the refractive index of the film satisfies nx = ny ≠nz. In this case, a case of ny <nz is referred to as a +C film, and a case of ny> nz is referred to as a -C film. In this regard, nx means the refractive index in the slow axis direction in the plane direction of the film or plate, ny means the refractive index in the direction perpendicular to the slow axis in the plane direction of the film or plate, and nz is the film Or it means the refractive index in the thickness direction of the plate.

In one example, the polarizing plate may include a retardation film. The retardation layer may be, for example, a quarter wave plate (QWP). The quarter wave plate may have a quarter wave phase delay characteristic. In the present specification, the term n-wavelength phase delay property refers to a property capable of retarding incident light by n times the wavelength of the incident light within at least a partial wavelength range. The quarter-wavelength phase delay characteristic may be a characteristic of converting incident linearly polarized light into elliptical polarized light or circularly polarized light, and conversely converting incident elliptical polarized light or circularly polarized light into linearly polarized light. As the quarter wave plate, a quarter wave plate generally manufactured and distributed in the related art field may be used. For example, a uniaxially stretched cycloolefin-based film, a uniaxially stretched polyethylene terephthalate film, a uniaxially stretched polycarbonate film, or a liquid crystal film may be used without limitation.

In one example, the optical laminate may further include a glass substrate. In this case, the adhesive layer may be positioned between the optical film and the glass substrate. Specifically, the optical laminate may sequentially include a polarizer, an adhesive layer, an adhesive layer, and a glass substrate.

In one example, the glass substrate may be included in the optical film. For example, when the optical film is a polarizing plate, the glass substrate may be a kind of protective film to protect the polarizer, and the adhesive layer is used to attach the polarizer and the glass substrate, or the side opposite the glass substrate where the glass substrate and the polarizer contact It can be placed on top and used to bond other members to the glass substrate.

In another example, the glass substrate may have a configuration separate from the optical film. For example, the glass substrate may be a part of a liquid crystal panel as a component that confines a liquid crystal layer, and in this case, the adhesive layer may be used to attach a polarizing plate and a liquid crystal panel.

The adhesive layer positioned on the optical film includes a block copolymer having an aromatic group. The aromatic group included in the adhesive layer may be effectively disposed in accordance with the change in the dimensions of the polarizer under high temperature conditions, thereby contributing to light leakage suppression. In addition, the block copolymer-containing adhesive layer of the present application has excellent build-up properties of adhesive strength.

In the present application, that the adhesive layer includes a copolymer means that the adhesive layer is formed from a composition containing the copolymer. In addition, the term "block copolymer" in the present application may refer to a copolymer including blocks of different polymerized monomers.

Specifically, the block copolymer includes a first block having a glass transition temperature of 50° C. or higher; And a polymerization unit derived from a monomer having a glass transition temperature of -10° C. or less and having both an aromatic group-containing monomer and a crosslinkable functional group may include a second block.

In the present application, the "glass transition temperature of a block" constituting the block copolymer is a glass transition temperature of a polymer formed only of monomers included in the block, and may be calculated according to the method described in the following examples.

With respect to the second block of the block copolymer, the concentration of the polymerization unit derived from the aromatic group-containing monomer is higher in a region adjacent to the first block than in a region not adjacent to the first block. Accordingly, the aromatic group is present at a high density in a region adjacent to the first block. The unit derived from the aromatic group or the aromatic group-containing monomer included in the second block and adjacent to the first block is, under high temperature conditions, when the stress due to the change in the size of the polarizing plate is concentrated on the adhesive, the chain of the first block is pulled. And can be effectively aligned. Therefore, even if the content of the polymerization unit having an aromatic group is small, it may be effective in reducing light leakage. In addition, when the concentration of the polymerized unit derived from the aromatic group or the aromatic group-containing monomer in the second block is higher in the portion adjacent to the first block, the glass transition of the second block region adjacent to the first block having a high glass transition temperature The temperature increases, and as a result, the volume of the region with a high glass transition temperature (hard region) inside the pressure-sensitive adhesive composition increases, increasing the adhesion to the substrate (eg, glass) adjacent to the pressure-sensitive adhesive layer, resulting in high temperature or high temperature and high humidity conditions. It is thought that the durability of the can be improved.

On the other hand, the glass transition temperature is high, and the hard property of the first block is small as described below, but this property is similar to that of a thickener that increases adhesion. That is, the distribution of the first block may bring about an increase in adhesion and build-up properties. As described below, the monomer having an aromatic group and the unit derived therefrom are located at a high concentration in the second block region adjacent to the first block. When viewed as a whole, the first block becomes bulky, and as a result, it is thought that high adhesion and build-up are secured.

In one example, the "concentration of the polymerized unit derived from the aromatic group-containing monomer" herein refers to the (meth)acrylic monomer (ie, including both methacrylic monomer and acrylic monomer) in the polymer forming the second block. It means the number of aromatic groups per 100 repeating units, and the higher the concentration, the more aromatic groups are distributed. Specifically, in a region in which the second block is adjacent to the first block, 10 to 50 aromatic groups per 100 repeating units of the acrylic monomer in the block copolymer, preferably 15 to 45, may be included in the first block. In a non-adjacent region, per 100 repeating units of the acrylic monomer in the polymer may be 9 or less, 8 or less, 7 or less, 6 or less, or 5 or less, and 0.1 to 5, preferably 0.5 It may be to three.

The adhesive layer having the block copolymer as described above has a faster build-up speed of adhesive strength when a predetermined time elapses compared to the prior art.

Specifically, the pressure-sensitive adhesive optical laminate may satisfy the following <Relational Formula 1> in peeling force against glass measured at a speed of 0.3 m/min and an angle of 180° according to JIS Z 0237.

<Relationship 1>

P2-P1 ≥ 150 (gf/25mm)

In the above relational equation 1, P1 is the peeling force measured after storage of the adhesive-type optical laminate specimen (S1) attached to the glass through an adhesive layer at room temperature and relative humidity in the range of 45 to 65% for 1 day, and P2 is It may be the peeling force measured after 3 days elapse after attaching the adhesive optical laminate specimen (S2) to the glass through the adhesive layer at room temperature and relative humidity in the range of 45 to 65%. At this time, the configuration of the specimen S1 and the specimen S2 is the same.

In the present application, room temperature, which is one of the measurement conditions for peeling force related to the build-up characteristic of adhesive force, refers to a temperature in a specially reduced or not heated state, and may mean a temperature within the range of 18 to 33°C, for example. have.

Satisfying the relational expression 1 as described above means that the increase in the adhesive strength after 3 days after adhesion of the adhesive is large enough to be 150 gf/25mm or more, that is, the build-up of the adhesive force is fast. In the case of having the build-up characteristics as shown in Relational 1, for example, after attaching an optical film such as a polarizing plate to the panel, it prevents lifting of the polarizing plate that can be caused by contraction and expansion of the polarizing plate under various temperature/humidity conditions where the panel is exposed. can do

In one example, the peel force P1 may be 450 gf/25mm or more. Specifically, it may be 460 gf/25mm or more, 470 gf/25mm or more, 480 gf/25mm or more, 490 gf/25mm or more, or 500 gf/25mm or more. If it is less than the above range, it may not have sufficient adhesive strength and durability. The upper limit of the peeling force P1 is not particularly limited, but when considering realistic adhesive force, for example, 650 gf/25mm or less, 640 gf/25mm or less, 630 gf/25mm or less, 620 gf/25mm or less, 610 gf/25mm It may be less than or less than 600 gf/25mm.

In one example, the peel force P2 may be 600 gf/25mm or more. Specifically, 610 gf/25mm or more, 620 gf/25mm or more, 630 gf/25mm or more, 640 gf/25mm or more, 650 gf/25mm or more, 660 gf/25mm or more, 670 gf/25mm or more, 680 gf/25mm or more , 690 gf/25mm or more or 700 gf/25mm or more. If it is less than the above range, the desired build-up characteristics may not be implemented. The upper limit of the peeling force P2 is not particularly limited, but considering realistic adhesive force, it may be, for example, 750 gf/25mm or less.

In another example, the pressure-sensitive adhesive optical laminate may satisfy the following <Relationship 2> in peeling force against glass measured at a speed of 0.3 m/min and an angle of 180° according to JIS Z 0237.

<Relationship 2>

P3-P1 ≥ 250 (gf/25mm)

In the above relational equation 2, P1 is the peeling force measured with respect to the adhesive-type optical laminate specimen (S1) attached to the glass through the adhesive layer at room temperature and relative humidity in the range of 45 to 65%, and P3 is at room temperature and 45 It may be a peeling force measured 7 days after attaching the adhesive optical laminate specimen (S3) to the glass through an adhesive layer in a relative humidity condition in the range of to 65%. At this time, the configuration of the specimen S1 and the specimen S3 is the same.

Satisfying the relational expression 2 as described above means that the increase in the adhesive strength after 7 days after the adhesive is attached is greater than 250 gf/25mm, that is, the build-up of the adhesive force is fast. If it has the build-up characteristics as shown in Relational Equation 2, for example, after attaching an optical film such as a polarizing plate to the panel, it prevents lifting of the polarizing plate, which can be caused by contraction and expansion of the polarizing plate under various temperature/humidity conditions where the panel is exposed. can do.

With respect to the relational equation 2, the range of the peel force P1 may be the same as described above.

In one example, the peel force P3 may be 700 gf/25mm or more. Specifically, 710 gf/25mm or more, 720 gf/25mm or more, 730 gf/25mm or more, 740 gf/25mm or more, 750 gf/25mm or more, 760 gf/25mm or more, 770 gf/25mm or more, 780 gf/25mm or more , 790 gf/25mm or more or 800 gf/25mm or more. If it is less than the above range, the desired build-up characteristics may not be implemented. The upper limit of the peeling force P3 is not particularly limited, but considering realistic adhesive force, it may be, for example, 950 gf/25mm or less.

In one example, the glass transition temperature of the first block may be 50°C or higher, 60°C or higher, 70°C or higher, 75°C or higher, 80°C or higher, or 85°C or higher. The upper limit of the first block glass transition temperature is not particularly limited, but, for example, 150°C or less, 140°C or less, 130°C or less, 120°C or less, 110°C or less, 100°C or less, 95°C or less, or 90°C or less It can be about. In the present application, the first block having a relatively high glass transition temperature may form a hard segment having relatively rigid physical properties in the block copolymer. The first block may exist in a glass form at room temperature, and may serve to impart a cohesive force to an adhesive including the block copolymer.

In one example, the glass transition temperature of the second block may be -10°C or less, -20°C or less, -30°C or less, -35°C or less, -40°C or less, or -45°C or less. The lower limit of the second block glass transition temperature is not particularly limited, but may be, for example, -80°C or higher, -70°C or higher, -60°C, -55°C or higher, -50°C or higher, or -45°C or higher. . The second block having a relatively low glass transition temperature may form a soft segment having soft physical properties in the block copolymer. The second block may have molecular flow at room temperature, and may serve to impart stress relaxation properties to the pressure-sensitive adhesive including the block copolymer.

The copolymer including both blocks satisfying the glass transition temperature range may form a fine phase-separated structure in the adhesive. Since the block copolymer exhibits adequate cohesive force and stress relaxation properties according to temperature changes, it forms a pressure-sensitive adhesive that maintains excellent physical properties required for optical films such as interfacial adhesion, high temperature durability reliability, light leakage prevention properties, and reworkability. can do.

In one example, the block copolymer of the present application including the two blocks may be a diblock copolymer or a triblock copolymer. In consideration of the interfacial adhesion of the pressure-sensitive adhesive, high temperature durability reliability, stress relaxation property and reworkability, a diblock copolymer may be advantageous.

As long as it has the specific functional group described above and can simultaneously have the glass transition temperature described above, the type or content of the monomer for forming each block is not particularly limited.

In one example, the first block and the second block may include a polymerization unit derived from an alkyl (meth) acrylate.

In the present application, the term "polymerization unit" may mean a state in which the predetermined monomer is polymerized and contained in a resin, a polymer, or a main chain or side chain of a polymerization reactant formed by polymerization of a predetermined monomer.

In one example, the type of alkyl (meta) acrylate used for forming the first block is 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, in consideration of cohesive strength, glass transition temperature, and adhesion control, etc. An alkyl (meth)acrylate having an alkyl group having 1 to 8 carbon atoms or 1 to 4 carbon atoms may be used. Examples of such monomers include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate )Acrylate, sec-butyl (meth)acrylate, pentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-ethylbutyl (meth)acrylate, n-octyl (meth)acrylate, iso Bornyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate and lauryl (meth) acrylate, etc., and one or more of the above has the glass transition temperature You can choose and use it as much as possible.

In one example, in consideration of the ease of controlling the glass transition temperature, the monomer forming the first block includes 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. Alkyl methacrylates having an alkyl group can be used.

In one example, the first block is an alkyl (meth)acrylate, a polymerization unit derived from an alkyl (meth)acrylate having an alkyl group having 1 to 3 carbon atoms and an alkyl (meth)acrylate having an alkyl group having 4 or more carbon atoms It may contain a polymerization unit of. In the case of having the above configuration, it may be advantageous in improving the high temperature durability of the pressure-sensitive adhesive. Specifically, since the alkyl (meth)acrylate having an alkyl group having 1 to 3 carbon atoms can cause chain entanglement more easily than an alkyl (meth)acrylate having 4 or more carbon atoms of the alkyl group, physical entanglement can occur instead of chemical crosslinking. Crosslinking can be sufficiently imparted to the adhesive resin, thereby providing an adhesive layer excellent in high temperature durability. In this case, the first block includes a polymerization unit derived from 60 to 75 parts by weight of an alkyl (meth)acrylate having an alkyl group having 1 to 3 carbon atoms and 25 to 40 parts by weight of an alkyl (meth)acrylate having an alkyl group having 4 or more carbon atoms. I can. Although not particularly limited, the alkyl (meth)acrylate having an alkyl group having 1 to 3 carbon atoms may be an alkyl methacrylate having an alkyl group having 1 to 3 carbon atoms, and the alkyl (meth)acrylate having an alkyl group having 4 or more carbon atoms is And an alkyl methacrylate having an alkyl group having 4 or more carbon atoms.

In one example, the first block may contain only a polymerization unit derived from an alkyl methacrylate. That is, the first block may be a polymer of only alkyl methacrylate monomers.

In one example, unlike the second block described below, the first block may not include both a crosslinkable functional group and an aromatic group. That is, in forming the first block, a polymerization unit derived from a monomer having a crosslinkable functional group and a monomer having an aromatic group may not be used.

In one example, the number average molecular weight (Mn) of the first block of the block copolymer may range from 2,500 to 150,000. The number average molecular weight of the first block may be, for example, the number average molecular weight of a polymer prepared by polymerizing only the monomers forming the first block. The number average molecular weight referred to in the present application can be measured according to the method presented in the following experimental examples using, for example, GPC (Gel Permeation Chromatograph). More specifically, the number average molecular weight (Mn) of the first block may be, for example, a lower limit of 10,000 or more, 20,000 or more, 30,000 or more, 40,000 or more, or 50,000 or more. More specifically, the lower limit of the number average molecular weight (Mn) of the first block may be, for example, 55,000 or more, 6,000 or more, 65,000 or more, 70,000 or more, 75,000 or more, 80,000 or more, 85,000 or more, 90,000 or more, or 95,000 or more. have. And the upper limit may be 145,000 or less, 140,000 or less, 135,000 or less, 130,000 or less, 125,000 or less, 120,000 or less, 115,000 or less, 110,000 or less, 105,000 or less, 100,000 or less, 95,000 or less, or 90,000 or less.

In another example, the ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the first block (Mw/Mn), that is, the molecular weight distribution (PDI=Mw/Mn) may be in the range of 1.0 to 3.0. . More specifically, the lower limit of the PDI value of the first block may be, for example, 1.00 or more, 1.05 or more, 1.15 or more, 1.20 or more, 1.25 or more, 1.30 or more, 1.35 or more, 1.40 or more, 1.45 or more, or 1.50 or more. And the upper limit may be, for example, 2.5 or less or 2.0 or less, and more specifically 1.95 or less, 1.90 or less, 1.85 or less, 1.80 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 I can.

In one example, the compound used for forming the second block is 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, as in the first block. The branch can be an alkyl (meth) acrylate.

In one example, the alkyl (meth)acrylate used to form the second block may be an alkyl acrylate. The alkyl acrylate is a main component of the second block, based on the weight of the second block, 50 parts by weight or more, 55 parts by weight or more, 60 parts by weight or more, 65 parts by weight or more, 70 parts by weight or more when forming the second block , 75 parts by weight or more or 80 parts by weight or more may be used, and the upper limit of the content may be, for example, 99 parts by weight or less, 98 parts by weight or less, 97 parts by weight or less, 96 parts by weight or less, or 95 parts by weight or less.

In the present application, the second block has both an aromatic group and a crosslinkable functional group. That is, the second block has a polymerized unit derived from an alkyl (meth)acrylate, an aromatic group-containing copolymerizable monomer, and a crosslinkable functional group-containing copolymerizable monomer.

The second block may contain a higher concentration of a polymerized unit derived from an aromatic group-containing monomer in a region adjacent to the first block. Accordingly, relatively, in a region of the second block adjacent to the first block, a polymerization unit derived from a crosslinkable functional group-containing monomer may be contained in a smaller concentration. Matters concerning the concentration of the crosslinkable functional group may follow the description of the concentration of the aromatic group (eg, the number of aromatic groups per 100 repeating units of the (meth)acrylic monomer). In this regard, as described below, in order to increase the concentration of the aromatic group-containing monomer in the second block region adjacent to the first block having a high glass transition temperature, the second block is prepared (more reactive than acrylate). A methacrylate-based monomer may be used as an aromatic group-containing monomer, and accordingly, a monomer connected first when forming the second block after the first block is formed may be mainly an aromatic group-containing methacrylate. Accordingly, the aromatic group may be adjacent to the first block, and when stress occurs in the high temperature and high temperature and high humidity conditions, when chain unwinding of the first block occurs, alignment of the adjacent aromatic groups may occur smoothly. In this case, since monomers having a high glass transition temperature, that is, methacrylate-based monomers, are collected near the first block having a high glass transition temperature, the volume fraction of the first block, which is advantageous for durability, may increase, and at the same time, a crosslinkable functional group or Since the units derived from the monomers are more distributed in the non-adjacent region of the first block (ie, the region of the second block), the second block with weak durability can be reinforced.

In one example, the aromatic group-containing copolymerizable monomer used in the second block may be a compound having a glass transition temperature of 30° C. or higher of the homopolymer. As explained through the following examples, assuming that the concentration of the polymerization unit derived from the aromatic group or the aromatic group-containing monomer is higher in the region adjacent to the first block, the glass transition temperature of the aromatic group-containing copolymerizable monomer is second When it is higher than the glass transition temperature of the block, heat resistance durability may be improved as the volume fraction of units derived from the monomer having a high glass transition temperature on the first block side increases.

In one example, the aromatic group-containing copolymerizable monomer may be an aromatic group-containing alkyl (meth)acrylate. The kind of the aromatic group-containing alkyl (meth)acrylate is not particularly limited, but, for example, benzyl (meth)acrylate or 2-phenoxy ethyl (meth)acrylate may be used. In addition, one or more of the above compounds may be used.

In one example, the aromatic group-containing copolymerizable monomer used in the second block may be an aromatic group-containing alkyl methacrylate. For example, benzyl methacrylate or 2-phenoxy ethyl methacrylate can be used. Since the reactivity of methacrylate during the production of the second block is greater than that of acrylate, the monomer that is first connected during the formation of the second block after the formation of the first block may be a polymerization unit derived mainly from methacrylate containing an aromatic group. Accordingly, the aromatic group may be adjacent to the first block, and when the chain unwinding of the first block occurs when stress occurs under high temperature and high temperature and high humidity conditions, alignment of the adjacent aromatic groups can occur smoothly, and at the same time, the durability of the second block is improved. Can be strengthened.

In one example, the second block may include a crosslinkable functional group that reacts with a crosslinking agent described below to form a crosslinked structure of the pressure-sensitive adhesive. When the crosslinkable functional group is included in the second block, it exhibits appropriate cohesive force and stress relaxation properties according to temperature changes to form a pressure-sensitive adhesive that maintains excellent physical properties such as interfacial adhesion, high temperature durability reliability, light leakage prevention properties, and reworkability. can do.

The kind of crosslinkable functional group is not specifically limited. For example, it may be a carboxyl group, a sulfonic acid group, a phosphate group, or a hydroxy group.

In one example, the crosslinkable functional group may be a hydroxy group (-OH). For example, the second block may include a polymerization unit derived from a hydroxy group-containing alkyl (meth)acrylate monomer. Alternatively, for example, the second block may include a polymerization unit derived from a hydroxy group-containing alkyl acrylate monomer.

In one example, the second block may include a hydroxy group (-OH) and may have a polymerization unit derived from a copolymerizable monomer represented by Formula 1 below.

However, in Formula 1, Q is hydrogen or an alkyl group, A and B are each independently an alkylene group or an alkylidene group, and n is an integer within the range of 0 to 10. In addition, when there are two or more [-O-B-] units in Formula 1, the number of carbon atoms of B in each [-O-B-] unit may be the same or different.

In the present specification, the term ``alkyl group'' is a linear, branched or cyclic 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 unless otherwise specified. It may mean, and the alkyl group may be optionally substituted with one or more substituents. As the alkyl group in Formula 1, a straight or branched alkyl group having 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms may be exemplified. Although not particularly limited, when Q in Formula 1 is an alkyl group, Q may be an alkyl group having 1 to 4 carbon atoms.

In the present specification, the term "alkylene group" or "alkylidene group" is a straight chain 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 unless otherwise specified. , It may mean a branched or cyclic alkylene group or an alkylidene group, and the above may be optionally substituted by one or more substituents. Although not particularly limited, in Formula 1, for example, A and B may each independently be a linear alkylene group having 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms.

In addition, n in Formula 1 may be, for example, 0 to 7, 0 to 5, 0 to 3, or 0 to 2.

Examples of the compound of Formula 1 include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate. ) Acrylate or hydroxy alkyl (meth) acrylate such as 8-hydroxyoctyl (meth) acrylate, and the like may be used. Or, hydroxyalkylene glycol (meth)acrylate such as 2-hydroxyethylene glycol (meth)acrylate or 2-hydroxypropylene glycol (meth)acrylate may be exemplified as a compound of Formula 1, but the compounds listed above It is not particularly limited to these.

In one example, in consideration of the reactivity of the monomer or the ease of controlling the glass transition temperature, the compound represented by Formula 1 may be hydroxyalkyl acrylate or hydroxyalkylene glycol acrylate.

In one example, the second block may include a polymerization unit derived from 0.5 to 15 parts by weight of a copolymerizable monomer having an aromatic group. More specifically, the second block is 1 part by weight or more, 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 It may include a polymerized unit derived from at least 9 parts by weight, or at least 10 parts by weight.

In one example, the second block may have a polymerization unit derived from 0.01 parts by weight to 15 parts by weight of a copolymerizable monomer having a crosslinkable functional group. Specifically, the second block is 0.05 parts by weight or more of a copolymerizable monomer having a crosslinkable functional group, and more specifically, the second block is 0.1 parts by weight or more, 0.5 parts by weight or more, 1 parts by weight or more of a copolymerizable monomer having a crosslinkable functional group , 1.5 parts by weight or more, 2.0 parts by weight or more, 2.5 parts by weight or more, 3.0 parts by weight or more, 3.5 parts by weight or more, 4.0 parts by weight or more, 4.5 parts by weight or more, or 5.0 parts by weight or more. . The upper limit of the content is, for example, 10 parts by weight or less, 9 parts by weight or less, 8 parts by weight or less, 7 parts by weight or less, 6 parts by weight or less, 5 parts by weight or less, 4 parts by weight or less, 3 parts by weight or less, 2 It may be less than or equal to 1 part by weight.

In one example, the second block is polymerized from 75 to 99 parts by weight of an alkyl acrylate, 0.5 to 15 parts by weight of a copolymerizable monomer having an aromatic group, and 0.01 to 15 parts by weight of a copolymerizable monomer having a crosslinkable functional group Can have units.

If it is less than the above content range, the optical compensation effect and durability may not be sufficient. In addition, when it exceeds the above range, the optical compensation may be excessively increased, and the birefringence may be increased in the opposite direction, and the price of the pressure-sensitive adhesive may increase.

In one example, the first block may include a polymerization unit derived from an alkyl methacrylate, and the second block may include a polymerization unit derived from an alkyl acrylate. The first block including the alkyl methacrylate has a high glass transition temperature and is advantageous for securing durability, and the second block including the alkyl acrylate has a low glass transition temperature, so it may be advantageous to implement adhesive performance.

The first block and/or the second block may further include a polymerization unit derived from any other comonomer, if necessary, for example, for control of a glass transition temperature. Such optional comonomers include (meth)acrylonitrile, (meth)acrylamide, N-methyl (meth)acrylamide, N-butoxy methyl (meth)acrylamide, N-vinyl pyrrolidone or N- Nitrogen-containing monomers such as vinyl caprolactam; Alkoxy alkylene glycol (meth)acrylic acid ester, alkoxy dialkylene glycol (meth)acrylic acid ester, alkoxy trialkylene glycol (meth)acrylic acid ester, alkoxy tetraalkylene glycol (meth)acrylic acid ester, alkoxy polyethylene glycol (meth)acrylic acid Ester, phenoxy alkylene glycol (meth) acrylic acid ester, phenoxy dialkylene glycol (meth) acrylic acid ester, phenoxy trialkylene glycol (meth) acrylic acid ester, phenoxy tetraalkylene glycol (meth) acrylic acid ester or phenoxy Alkylene oxide group-containing monomers such as polyalkylene glycol (meth)acrylic acid ester; 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, but is not limited thereto. These comonomers may be used in an amount of, for example, 20 parts by weight or less, 15 parts by weight or less, 10 parts by weight or less, 5 parts by weight or less, or 1 part by weight or less based on the total weight of the block in each block. When any comonomer is used, the lower limit of its content may be, for example, 0.1 parts by weight.

In one example, the block copolymer may have a number average molecular weight (Mn) in the range of 50,000 to 300,000. More specifically, the lower limit of the number average molecular weight (Mn) of the block copolymer is, for example, 110,000 or more, 115,000 or more, 120,000 or more, 125,000 or more, 130,000 or more, 135,000 or more, 140,000 or more, 145,000 or more, 150,000 or more, 155,000 or more. , 160,000 or more, 165,000 or more, 170,000 or more, 175,000 or more, 180,000 or more, 185,000 or more, 190,000 or more, 195,000 or more, 200,000 or more, 210,000 or more, 215,000 or more, 220,000 or more, 225,000 or more, or 230,000 or more. And the upper limit may be, for example, 295,000 or less, more specifically 290,000 or less, 285,000 or less, 280,000 or less, 275,000 or less, 270,000 or less, 265,000 or less, 260,000 or less, 255,000 or less, 250,000 or less, 245,000 or less, or 240,000 or less. .

In another example, the molecular weight distribution (PDI=Mw/Mn) of the block copolymer may range from 1.5 to 4.0. Specifically, the lower limit of the molecular weight distribution of the block copolymer may be, for example, 2.0 or more or 2.5 or more. More specifically, the lower limit is 2.55 or more, 2.60 or more, 2.65 or more, 2.70 or more, 2.75 or more, 2.80 or more, 2.85 or more, 2.90 or more, 2.95 or more, 3.00 or more, 3.05 or more, 3.10 or more, 3.15 or more, 3.20 or more, 3.25 It may be greater than or equal to 3.30. And, the upper limit may be, for example, 3.45 or less, 3.40 or less, 3.35 or less, 3.30 or less, 3.25 or less, 3.20 or less, 3.15 or less, or 3.10 or less.

As described above, when the molecular weight characteristics of the block copolymer are adjusted, a pressure-sensitive adhesive that maintains excellent physical properties required for an optical film such as interfacial adhesion, high temperature durability reliability, light leakage prevention property, and reworkability can be formed.

In one example, the block polymer of the present application may include 5 parts by weight to 25 parts by weight of the first block and 75 parts by weight to 95 parts by weight of the second block. In another example, the block copolymer may include 10 parts by weight to 20 parts by weight of the first block and 80 parts by weight to 90 parts by weight of the second block.

A method of preparing the block copolymer is not particularly limited, and a known method may be used. For example, the block polymer may be polymerized in a LRP (Living Radical Polymerization) method. Specifically, an anionic polymerization method in which an organic rare earth metal complex is used as a polymerization initiator or an organic alkali metal compound is used as a polymerization initiator in the presence of an inorganic acid salt such as an alkali metal or alkaline earth metal salt, or an organic alkali metal compound is polymerized. Anionic polymerization method that is used as an initiator and synthesized in the presence of an organic aluminum compound, atomic transfer radical polymerization method (ATRP) using an atom transfer radical polymerization agent as a polymerization control agent, and an atom transfer radical polymerization agent as a polymerization control agent. ARGET (Activators Regenerated by Electron Transfer) atom transfer radical polymerization (ATRP), ICAR (Initiators for continuous activator regeneration) atom transfer radical polymerization (ATRP), reversible addition of inorganic reducing agents- Polymerization by reversible addition-cleavage chain transfer using a cleavage chain transfer agent (RAFT), or a method using an organic tellurium compound as an initiator may be used, and an appropriate method is selected from the above methods to prepare the block copolymer. I can.

In one example, the adhesive layer may further include a crosslinking agent. That is, the adhesive layer may be formed by curing a composition comprising a block copolymer and a crosslinking agent. In this case, the term "curing" may mean a process in which at least two components included in the pressure-sensitive adhesive composition chemically react with each other by irradiation and/or heating of electromagnetic waves. In the range of the term ``electromagnetic wave'' in the above, microwaves, infrared (IR), ultraviolet (UV), X-rays and gamma rays, as well as alpha-particle beams, proton beams, Particle beams such as a neutron beam and an electron beam may be included.

In one example, the crosslinking agent may be a compound having at least two or more functional groups capable of reacting with a crosslinkable group included in the block copolymer, that is, a multifunctional crosslinking agent. As the crosslinking agent, as a crosslinking agent capable of undergoing a crosslinking reaction by application of heat, an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, or a metal chelate crosslinking agent may be exemplified.

In one example, when the crosslinkable functional group introduced into the block copolymer is a hydroxy group, an isocyanate-based crosslinking agent may be used as the crosslinking agent. Examples of the isocyanate crosslinking agent include diisocyanate compounds such as tolyene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isoborone diisocyanate, tetramethylxylene diisocyanate or naphthalene diisocyanate, Alternatively, a compound obtained by reacting the diisocyanate compound with a polyol may be used, and as the polyol, for example, trimethylol propane may be used.

In one example, the crosslinking agent may be included in the composition in an amount of 0.001 parts by weight or more, based on 100 parts by weight of the block copolymer. Specifically, the content of the multifunctional crosslinking agent may be, for example, 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, or 0.05 or more, and more specifically, the content of the crosslinking agent is 0.10 or more, 0.15 or more, 0.20 or more, It may be 0.25 or more, 0.30 or more, 0.35 or more, 0.40 or more, 0.45 or more, or 0.50 or more. The upper limit of the content of the multifunctional crosslinking agent is not particularly limited, but may be, for example, 10 parts by weight or less or 5 parts by weight or less, and specifically, 4 parts by weight or less, 3 parts by weight or less, 2 parts by weight or less, or 1 part by weight It may be less than or equal to part. In this range, the gel fraction, cohesion, adhesion, and durability of the pressure-sensitive adhesive can be excellently maintained.

In one example, the adhesive layer may further include a silane coupling agent. That is, the adhesive layer may be formed by curing a composition containing a block copolymer, a crosslinking agent, and a silane coupling agent. The specific kind of the silane coupling agent is not limited. For example, a silane coupling agent containing any one of an epoxy group, a thiol group, an amino group, a vinyl group, an epoxy group, a beta-cyanoacetyl group, an acetoacetyl group or a halogen may be used.

In one example, the silane coupling agent may be a compound having a beta-cyano group or one or more selected from compounds having an acetoacetyl group. Specifically, the silane coupling agent may be at least one selected from a compound having a beta-cyano group represented by the following formula (A) and a compound having an acetoacetyl group represented by the following formula (B).

[Formula A]

(R ₁ ) _n Si(R ₂ ) _(4-n)

[Formula B]

(R ₃ ) _n Si(R ₂ ) _(4-n)

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

In Formula A or B, 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 such an alkyl group may be linear, branched or cyclic. I can. In addition, in Formula 1 or 2, 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 such an alkoxy group may be a linear, branched or ring It can be a prize.

Examples of the compound represented by Formula A or B include acetoacetylpropyl trimethoxysilane, acetoacetylpropyl triethoxy silane, beta cyanoacetylpropyl trimethoxysilane or beta cyanoacetylpropyl triethoxy silane. However, it is not particularly limited thereto.

In one example, the adhesive layer may include 5 parts by weight or less or 3 parts by weight or less, more specifically 1 part by weight or less of the silane coupling agent, based on 100 parts by weight of the block copolymer. Specifically, the content of the silane coupling agent may be 0.5 parts by weight or less, 0.4 parts by weight or less, 0.3 parts by weight or less, 0.2 parts by weight or less, or 0.1 parts by weight or less. The lower limit is not particularly limited, but may be, for example, 0.01 parts by weight or 0.02 parts by weight. In the case of the adhesive layer of the present application, even if it contains a small amount of a silane coupling agent, since it has excellent build-up properties of adhesive strength, it has excellent adhesion to a substrate (eg, glass) adjacent to the adhesive layer.

In one example, the thickness of the adhesive layer may be 35 μm or less. Specifically, the thickness of the adhesive layer may be 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less. Although not particularly limited, the lower limit of the thickness of the adhesive layer may be, for example, 10 μm or more. Preferably it may be in the range of 20 to 25 μm. It is possible to secure appropriate build-up characteristics or durability within the above range. On the other hand, when the thickness of the adhesive layer is too thin, the durability is not sufficient, and when the thickness is too large, there is a problem such as an increase in price.

In one example, each of the adhesive layers may further include a tackifier, if necessary. As the tackifier, for example, a hydrocarbon resin or a hydrogenated product thereof, a rosin resin or a hydrogenated product thereof, a rosin ester resin or a hydrogenated product thereof, a terpene resin or a hydrogenated product thereof, a terpene phenol resin or a hydrogenated product thereof, a polymerized rosin resin or One kind or two or more kinds of polymerized rosin ester resins, etc. may be mixed and used, but the present invention is not limited thereto. The tackifier may be used in a composition for forming each adhesive layer in an amount of 100 parts by weight or less based on 100 parts by weight of the block copolymer.

The method of forming each adhesive layer of the above-described configuration on the optical film is not particularly limited. For example, a method of coating an adhesive layer prepared on a separator (release film) on an optical film, and then sequentially laminating the adhesive layer prepared on a separate separator on the adhesive layer of the optical film can be used. have.

A specific method of forming the adhesive layer is also not particularly limited. For example, a method of implementing a crosslinked structure by directly coating and curing an adhesive composition on a substrate such as a polarizing plate, or coating and curing the adhesive composition on the release-treated surface of a release film to form a crosslinked structure Afterwards, a method of transferring it can be used. When coating the adhesive composition, for example, a conventional means such as a bar coater can be used.

It is preferable from the viewpoint of performing a uniform coating process that the crosslinking agent included in the pressure-sensitive adhesive composition is controlled so that the crosslinking reaction of the functional group does not proceed. Through this, the crosslinking agent forms a crosslinked structure in the curing and aging process after the coating operation, thereby improving the cohesiveness of the pressure-sensitive adhesive, and improving adhesive properties and cuttability.

In addition, the coating process is preferably carried out after sufficiently removing bubbles-causing components such as volatile components or reaction residues in the pressure-sensitive adhesive composition, and accordingly, the crosslinking density or molecular weight of the pressure-sensitive adhesive is too low, so that the elastic modulus decreases, and in a high temperature state Bubbles existing between the glass plate and the adhesive layer become large, thereby preventing a problem of forming a scattering body inside.

After coating, a method of implementing a crosslinked structure by curing the adhesive composition is not particularly limited. For example, the coating layer may be maintained at an appropriate temperature so that a crosslinking reaction between the block copolymer included in the coating layer and the crosslinking agent may be induced.

After coating, a method of implementing a crosslinked structure by curing the coated pressure-sensitive adhesive composition is also not particularly limited. For example, a method of maintaining the coating layer at an appropriate temperature so that a crosslinking reaction between the block copolymer included in the coating layer and the crosslinking agent may be induced may be used.

According to the present application having the above configuration, an aromatic group is concentrated on one side of the adhesive layer to effectively compensate for birefringence caused by a change in the size of a polarizing plate at a high temperature, and to have an excellent effect in suppressing light leakage. In addition, it has excellent high-temperature, high-temperature, and high-humidity durability reliability, and particularly, it is possible to minimize lifting on a glass substrate.

In another example relating to the present application, the present application also relates to a display device. When the display device is an LCD, the device may include a liquid crystal panel and the polarizing plate or optical laminate attached to one or both sides of the liquid crystal panel. The polarizing plate or the optical laminate may be attached to the liquid crystal panel by the pressure-sensitive adhesive described above.

The liquid crystal panel may include, for example, a first substrate sequentially formed, a pixel electrode, a first alignment layer, a liquid crystal layer, a second alignment layer, a common electrode, and a second substrate. In one example, the first substrate and the second substrate may be a glass substrate. In this case, the polarizing plate or the optical laminate may be attached to the glass substrate via the pressure-sensitive adhesive layer described above.

The device may further include a light source on a side opposite to the viewing side of the liquid crystal panel. On the first substrate on the light source side, for example, an active driving circuit including a TFT (Thin Film Transistor) and wiring as a driving element electrically connected to a transparent pixel electrode may be formed. The pixel electrode may include, for example, Indium Tin Oxide (ITO), and may function as an electrode for each pixel. In addition, the first or second alignment layer may include, for example, a material such as polyimide, but is not limited thereto.

Examples of the liquid crystal panel in the apparatus include a passive matrix type panel such as a twisted nematic (TN) type, a super twisted nematic (STN) type, a ferroelectic (F) type, or a polymer dispersed (PD) type; An active matrix type panel such as a two terminal type or a three terminal type; Known panels, such as an IPS (In Plane Switching) panel and a vertical alignment (VA) panel, may all be applied.

Other configurations of the display device, for example, the type of upper and lower substrates such as a color filter substrate or an array substrate in a liquid crystal display device are not particularly limited, and configurations known in the art may be employed without limitation.

In another example related to the present application, the present application includes a crosslinkable adhesive composition capable of forming the adhesive layer. Description of the block copolymer, the crosslinking agent, and other components included in the pressure-sensitive adhesive composition are as described above.

According to an example of the present application, an optical laminate having excellent build-up characteristics of adhesive force and light leakage suppression characteristics, and an apparatus including the same are provided.

Hereinafter, the present application will be described in detail through examples. However, the scope of protection of the present application is not limited by the examples described below.

<Measurement or evaluation items>

1. Molecular weight property evaluation

The number average molecular weight (Mn) and molecular weight distribution (PDI) of the copolymer were measured using GPC (Gel Permeation Chromatography), and the measurement conditions for GPC are as follows. The measurement results were converted using standard polystyrene (Agilent system (manufactured)) to prepare a calibration curve.

<GPC measurement conditions>

Measuring instrument: Agilent GPC (Agilent 1200 series, U.S.)

Column: Connect 2 PL Mixed B

Column temperature: 40°C

Eluent: THF (Tetrahydrofuran)

Flow rate: 1.0 mL/min

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

2. Glass transition temperature

The glass transition temperature (Tg) of each block of the block copolymer or block copolymer was calculated according to Equation A below.

<Equation A>

1/Tg=∑Wn/Tn

In Equation A, Wn is the weight fraction of the block copolymer or the monomer applied to each block of the copolymer, and Tn represents the glass transition temperature when each corresponding monomer forms a homopolymer. That is, in Equation A, the right side is the result of summing the calculated values after calculating all of the values (Wn/Tn) by dividing the weight fraction of the monomer used by the glass transition degree indicated when the monomer forms a homopolymer. to be.

3. Light transmission Uniformity( Light leak ) evaluation

The pressure-sensitive adhesive composition prepared in Examples and Comparative Examples was cut to have a width of about 200 mm and a length of about 200 mm, and on both sides of a soda lime glass having a width of 250 mm and a length of 250 mm. Attached crosswise at 90°. Thereafter, the glass substrate to which the polarizing plate is attached is stored in an autoclave (50° C. 5 atm) for about 20 minutes to prepare a sample. The prepared sample was stored in an oven at 80° C. for 72 hours and then mounted on a back light unit at room temperature, and the uniformity of light transmittance was observed and evaluated based on the following criteria.

<Light transmission uniformity evaluation criteria>

A: It is difficult to judge the non-uniformity of light transmittance with the naked eye.

B: There is a slight non-uniformity of light transmission

C: There is some non-uniformity of light transmission

D: There is a large amount of non-uniformity in light transmission

4. Evaluation of durability

The polarizing plates prepared in Examples and Comparative Examples were cut to have a width of about 180 mm and a length of about 320 mm, and attached to a commercially available liquid crystal panel of 19 inches. Then, the liquid crystal panel to which the polarizing plate is attached is stored in an autoclave (50° C. 5 atm) for about 20 minutes to prepare a sample. Moisture and heat resistance of the prepared sample was evaluated by the following criteria by observing the occurrence of bubbles and peeling at the adhesive interface after the sample was left at 65° C. and 95% relative humidity for 500 hours. After holding at °C for 500 hours, each occurrence of bubbles and peeling was observed and evaluated according to the following criteria.

<Evaluation criteria for heat and moist heat resistance>

A: No bubbles and peeling occurred

B: Some bubbles and/or peeling occurred

C: A large amount of bubbles and/or peeling occurs

5. Adhesion and adhesion to glass Build-up evaluation

The adhesive polarizing plate prepared in Examples or Comparative Examples was cut to have a width of 25 mm and a length of 100 mm to prepare a specimen. Subsequently, the release PET film adhered to the pressure-sensitive adhesive layer is peeled off, and the pressure-sensitive adhesive polarizing plate is adhered to the soda lime glass using a 2 kg roller according to JIS Z 0237. A sample is prepared by compressing the glass to which the polarizing plate is attached for about 20 minutes in an autoclave (50°C, 5 atm), and storing it in a constant temperature and humidity condition (23°C, 50% relative humidity) for 24 hours. Thereafter, using a TA equipment (Texture Analyzer, manufactured by Stable Micro Systems Co., Ltd.), the polarizing plate was peeled from the glass at a peeling rate of 0.3 m/min and a peeling angle of 180° to measure the peel force.

In addition, according to the time (3 days and 7 days) left in constant temperature and humidity conditions, the adhesive polarizing plate sample attached to the glass was taken out and the adhesive strength was measured to confirm the degree of build-up of the adhesive force.

< Manufacturing example >

Manufacturing example 1. Preparation of block copolymer (A1)

EBiB (ethyl 2-bromoisobutyrate) 0.032 g, methyl methacrylate (MMA) 8.0 g, butyl methacrylate (BMA) 3.6 g were mixed with ethyl acetate (EAc) 7.7 g. The reactor containing the mixture was sealed, purged and stirred with nitrogen at about 25° C. for about 30 minutes, and dissolved oxygen was removed through bubbling. Thereafter, 0.002 g of CuBr2, 0.006 g of TPMA (tris(2-pyridylmethyl)amine) and 0.003 g of V-65 (2,2'-azobis(2,4-dimethyl valeronitrile)) were added to the mixture from which oxygen was removed. Then, the reaction was initiated in a reaction tank at about 67°C (polymerization of the first block). When the conversion rate of methyl methacrylate is about 70%, 89.0 g of butyl acrylate (BA) previously bubbled with nitrogen, 1.1 g of hydroxybutyl acrylate (HBA), 2-phenoxy ethyl methacrylate ( A mixture of 4.7 g of PEMA) and 251 g of ethyl acetate (EAc) was added in the presence of nitrogen. Thereafter, 0.004 g of CuBr2, 0.01 g of TPMA and 0.01 g of V-65 were added to the reactor, and a chain extension reaction was performed (polymerization of the second block). When the conversion ratio of the monomer (BA) reached 80% or more, the reaction mixture was exposed to oxygen and diluted in an appropriate solvent to terminate the reaction to prepare a block copolymer (V-65 in the above process is It was appropriately divided and added until the reaction was completed.

Manufacturing example 2 to 3. Preparation of block copolymers (A2 to A4)

A block copolymer was prepared in the same manner as in Preparation Example 1, except that the raw materials used in the polymerization of the first block and the second block were adjusted in the ratio shown in Table 1 below.

[Table 1]

Manufacturing example 3. Preparation of random copolymer (B1)

Consists of 99 parts by weight of n-butylacrylate (BA) and 1 part by weight of hydroxybutyl acrylate (HBA) in a reactor equipped with a cooling device to facilitate nitrogen gas reflux and temperature control. A mixture of monomers was added. Then, 200 parts by weight of ethylacetate (EAc) was added as a solvent. After purging nitrogen gas for 60 minutes to remove oxygen, the temperature was maintained at 60°C, and 0.04 parts by weight of azobisisobutyronitrile (AIBN) as a reaction initiator was added and reacted for 8 hours at random. Copolymer (B1) was prepared. The weight average molecular weight of copolymer (B1) was 1.55 million and molecular weight distribution was 6.2.

Manufacturing example 4. Random Preparation of copolymer (B2)

89 parts by weight of n-butylacrylate (BA) and 1 part by weight of hydroxybutyl acrylate (HBA) in a 1L reactor equipped with a cooling device to facilitate nitrogen gas reflux and temperature control , A mixture of monomers consisting of 10 parts by weight of benzyl acrylate (BzA) was added. Then, 200 parts by weight of ethylacetate (EAc) was added as a solvent. After purging nitrogen gas for 60 minutes to remove oxygen, the temperature was maintained at 60°C, and 0.06 parts by weight of azobisisobutyronitrile (AIBN) as a reaction initiator was added and reacted for 8 hours at random. Copolymer (B2) was prepared. The weight average molecular weight was 1.56 million and molecular weight distribution was 6.8.

< Example And Comparative example >

Example One

Preparation of coating solution (adhesive composition)

Crosslinking agent (Coronate L, manufactured by NPU in Japan) 0.15 parts by weight, DBTDL (Dibutyltin dilaurate) 0.01 parts by weight, silane coupling agent (M812, manufactured by LG Chemical) 0.1 based on 100 parts by weight of the block copolymer (A1) prepared in Preparation Example 1 A coating solution (adhesive composition) was prepared by mixing parts by weight and mixing ethyl acetate as a solvent to adjust the coating solid content to about 30% by weight.

Preparation of adhesive polarizing plate

The prepared coating solution was coated on the release-treated surface of 38 μm-thick release PET (poly(ethylene terephthalate)) (MRF-38, manufactured by Mitsubishi), which was subjected to release treatment so that the thickness after drying was about 23 μm, and then in an oven at 95°C. Hold for about 3 minutes. After drying, a coating layer formed on the release PET was laminated on one side of a polarizing plate (stack structure of COP/PVA/COP: COP=cyclic olefin polymer, PVA=polyvinyl alcohol polarizing film) to prepare an adhesive polarizing plate.

Example 2 to 3 and Comparative example 1 to 4

When preparing the pressure-sensitive adhesive composition (coating solution), a pressure-sensitive adhesive composition (coating solution) and a pressure-sensitive adhesive polarizing plate were prepared in the same manner as in Example 1, except that each component and ratio were adjusted as shown in Table 2 below.

[Table 2]

[Table 3]

In the case of Examples 1 to 3 using PEMA and BzMA when forming the second block, it can be seen that excellent light leakage suppression ability is shown. On the other hand, in the case of Comparative Example 2 in which BzA was added to the second block, the ability to suppress light leakage was not as good as in Example 3 even though the content of BzA in the entire pressure-sensitive adhesive composition was similar to that of Example 3. This is because the reactivity of methacrylate is greater than that of acrylate, and the monomer that is connected to the first block in the second block production step becomes a methacrylate polymerized unit having an aromatic group. As a result, the aromatic group is the first It is thought to be due to the reason adjacent to the block. Accordingly, since the aromatic group has a higher concentration as it is closer to the first block, when the chain unwinding of the first block occurs while stress occurs under high temperature and high temperature and high humidity conditions, alignment of adjacent aromatic groups may occur more smoothly in the embodiment. will be. In other words, the higher the concentration of the aromatic group in the region adjacent to the first block in the second block is higher than that in the region far from the first block, the more efficiently the arrangement of the aromatic rings occurs, and as a result, it will be interpreted as advantageous for optical compensation. I can.

Comparing the degree of build-up of adhesion or adhesion between glass-adhesive over time, if PEMA or BzMA is used for 2 blocks, it can be seen that the build-up is made faster due to increased adhesion over time after glass lamination. . This suggests that the invention of the present application can prevent lifting of the adhesive polarizing plate under severe conditions.

In addition, when looking at the heat resistance durability evaluation results, it can be seen that Comparative Example 2 contains an aromatic group in an amount similar to that of Example 3, but the heat resistance durability is not good compared to Example 3. It is believed that this is because monomers having a high glass transition temperature are gathered near the first block having a high glass transition temperature, thereby increasing the volume fraction of a portion advantageous for durability.

Claims (18)

Optical film; And an adhesive layer having a block copolymer having an aromatic group,
The block copolymer includes 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 less and having a polymerization unit derived from an aromatic group-containing monomer and a monomer having a crosslinkable functional group,
The concentration of the polymerized unit derived from the aromatic group-containing monomer in the second block is higher in a region adjacent to the first block than in a region not adjacent to the first block,
Adhesive-type optical laminate in which the peeling force against the glass measured at a speed of 0.3 m/min and an angle of 180° according to JIS Z 0237 satisfies the following <Relationship Formula 1>:
<Relationship 1>
P2-P1 ≥ 150 (gf/25mm)
(However, in the above relational equation 1, P1 is the peeling force measured after storing the adhesive optical laminate specimen (S1) attached to the glass through the adhesive layer at room temperature and relative humidity in the range of 45 to 65% for 1 day. , P2 is the peeling force measured 3 days after attaching the adhesive optical laminate specimen (S2) to the glass through the adhesive layer at room temperature and relative humidity in the range of 45 to 65%, and at this time ) And the specimen (S2) have the same configuration.) The adhesive type optical laminate according to claim 1, which satisfies the following <relational formula 2>:
<Relationship 2>
P3-P1 ≥ 250 (gf/25mm)
(However, in the above relational equation 2, P1 is the peeling force measured after storing the adhesive optical laminate specimen (S1) attached to the glass through the adhesive layer at room temperature and relative humidity in the range of 45 to 65% for 1 day. , P3 is the peeling force measured 7 days after attaching the adhesive optical laminate specimen (S3) to the glass through the adhesive layer at room temperature and relative humidity in the range of 45 to 65%, and at this time, the specimen (S1 ) And the specimen (S3) have the same configuration.) The adhesive-type optical laminate according to claim 1, wherein the first block and the second block have a polymerized unit derived from an alkyl (meth)acrylate. The adhesive-type optical laminate according to claim 3, wherein the first block contains only polymerized units derived from alkyl methacrylate. The adhesive-type optical layered product according to claim 4, wherein the first block is composed of an alkyl methacrylate having 1 to 3 carbon atoms of the alkyl group and an alkyl methacrylate having 4 or more carbon atoms of the alkyl group. The adhesive type optical laminate according to claim 4, which does not contain a crosslinkable functional group and an aromatic group. The adhesive optical laminate of claim 1, wherein the first block has a number average molecular weight in the range of 2,500 to 150,000. According to claim 1, wherein the number average molecular weight of the block copolymer is in the range of 50,000 to 300,000, the molecular weight distribution [weight average molecular weight (Mw) / number average molecular weight (Mn)] of the block copolymer is in the range of 1.0 to 4.0 Type optical laminate. The method of claim 3, wherein the second block is derived from 75 to 99 parts by weight of an alkyl acrylate, 0.5 to 15 parts by weight of a copolymerizable monomer having an aromatic group, and 0.01 to 15 parts by weight of a copolymerizable monomer having a crosslinkable functional group. Adhesive-type optical laminate having a polymerized unit. The pressure-sensitive adhesive optical laminate according to claim 9, wherein the second block has a polymerization unit derived from an aromatic group-containing alkyl methacrylate. The adhesive-type optical laminate according to claim 10, wherein the second block has a polymerization unit derived from hydroxyalkyl acrylate or hydroxyalkylene glycol acrylate. The adhesive-type optical laminate according to claim 11, wherein the concentration of the polymerized unit derived from the monomer having a crosslinkable functional group is lower in a region adjacent to the first block than in a region not adjacent to the first block. The adhesive type optical laminate of claim 3, wherein the block copolymer is a diblock copolymer, and includes 5 to 25 parts by weight of the first block and 75 to 95 parts by weight of the second block. The adhesive-type optical laminate of claim 1, wherein the adhesive layer further comprises a crosslinking agent in the range of 0.001 to 10 parts by weight based on 100 parts by weight of the block copolymer. The method of claim 1, wherein the adhesive layer further comprises a silane coupling agent,
The adhesive layer is a pressure-sensitive adhesive optical laminate comprising 0.2 parts by weight or less of a silane coupling agent based on 100 parts by weight of the block copolymer. The adhesive optical laminate according to claim 1, wherein the adhesive layer has a thickness of 35 μm or less. The adhesive type optical laminate according to claim 1, wherein the optical film is a polarizer. Liquid crystal panel; And the optical laminate according to claim 1.