KR102166466B1 - Pressure sensitive adhesive composition - Google Patents

Abstract

The present application relates to an adhesive composition, a protective film, an optical laminate, an adhesive polarizing plate, and a display device. The present application can provide an adhesive composition that has excellent heat resistance and moisture heat resistance durability and can minimize light leakage even when exposed under severe conditions such as high temperature or high temperature and high humidity.

Description

Adhesive composition {PRESSURE SENSITIVE ADHESIVE COMPOSITION}

The present application relates to an adhesive composition, an optical laminate, a polarizing plate, and a display device.

A liquid crystal display device (hereinafter, ``LCD device'') is a liquid crystal panel including a liquid crystal component injected between two transparent substrates, and optical devices such as a polarizing film, a retardation film, or a brightness enhancing film. It is generally constructed to include a film. At this time, the adhesive is mainly used for lamination between the optical films or for attaching the optical film to the liquid crystal film.

On the other hand, acrylic polymer, rubber, urethane resin, silicone resin, or ethylene vinyl acetate (EVA) resin may be used as the pressure-sensitive adhesive. In consideration of transparency and resistance to oxidation or yellowing, acrylic copolymers are widely used in pressure-sensitive adhesives for attaching optical films. Used. However, in order to use a pressure-sensitive adhesive including an acrylic copolymer for attaching an optical film, improvement in cohesion, adhesion, reworkability, low light leakage characteristics, and stress relaxation properties is still required.

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

Another object of the present application is to provide an adhesive composition having improved durability and reliability light leakage characteristics even under severe conditions of high temperature and/or high humidity, and an optical product including the same.

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

In one example related to the present application, the present application relates to an adhesive composition. The adhesive composition may include a block copolymer. In the present application, the term "block copolymer" may mean a copolymer including blocks of different polymerized monomers.

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 constituting the block copolymer may mean a glass transition temperature measured from a polymer formed only of monomers formed in the block.

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, 80°C or higher, or 90°C or higher. The upper limit of the glass transition temperature of the first block is not particularly limited, but may be, for example, 200° C. or less.

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, -40°C or less, or -50°C or less. The lower limit of the glass transition temperature of the second block is not particularly limited, but may be, for example, -80°C or higher.

The copolymer of the present application including both blocks satisfying the glass transition temperature range may form a fine phase-separated structure in the adhesive. Since such a block copolymer exhibits adequate cohesive strength 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, durability reliability, light leakage prevention properties, and reworkability. Make it possible.

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. In the present application, the number average molecular weight (Mn) may be measured according to the method presented in the examples using, for example, GPC (Gel Permeation Chromatograph). More specifically, the number average molecular weight of the first block may be in the range of 5,000 to 100,000 or 10,000 to 50,000, for example.

In one example, the ratio (Mw/Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the first block, that is, the molecular weight distribution (PDI = Mw/Mn) may range from 1.0 to 3.0. More specifically, the molecular weight distribution of the first block may have a lower limit of 1,0 or more, 1.1 or more, 1.2 or more, and 1.3 or more, and an upper limit thereof may be 3.0 or less, 2.0 or less, or 1.5 or less.

In one example, the block copolymer may have a number average molecular weight of 50,000 to 500,000. More specifically, the number average molecular weight of the block copolymer may be 100,000 or more, 130,000 or more, 150,000 or more, or 180,000 or more, and its upper limit may be 300,000 or less, 250,000 or less, 230,000 or less, 200,000 or less, 180,000 or less, or 150,000 or less.

In one example, the molecular weight distribution (PDI=Mw/Mn) of the block copolymer may range from 1.0 to 2.5. More specifically, the lower limit of the molecular weight distribution of the block copolymer may be, for example, 1.3 or more, 1.4 or more, 1.5 or more, 1.6 or more, 1.7 or more, or 1.8 or more, and the upper limit is, for example, 2.5 or less, 2.4 It may be less than, 2.3 or less, 2.2 or less, 2.1 or less, or 2.0 or less.

When the molecular weight properties of the block copolymer are adjusted within the above range, physical properties such as interfacial adhesion, durability reliability, light leakage prevention properties, and reworkability required for an optical film adhesive can be excellently maintained.

The block copolymer may be a crosslinkable copolymer having a crosslinkable functional group. Examples of the crosslinkable functional group include a hydroxy group, a carboxyl group, an epoxy group, an isocyanate group, or a nitrogen-containing functional group.

When a crosslinkable functional group is included, the functional group may be included in any one of the first block or the second block, or may be included in both the first and second blocks.

In one example, the crosslinkable functional group may be included in the second block. In this case, the crosslinkable functional group may not be 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, it is possible to provide a pressure-sensitive adhesive that exhibits appropriate cohesive strength and stress relaxation properties according to temperature changes, and maintains excellent physical properties such as interfacial adhesion, durability reliability, light leakage prevention properties, and reworkability. I can.

The types of monomers constituting the first block and the second block are not particularly limited as long as the glass transition temperature range and the molecular weight range of each block mentioned above can be secured.

In one example, the first block may be a polymer of (meth)acrylic acid ester monomer. More specifically, the first block may include a polymerized unit derived from a (meth)acrylic acid ester monomer. In the present application, that the monomer is included in the polymer or block as a polymerized unit may mean that the monomer forms a skeleton of the polymer or block, for example, a main chain or a side chain through a polymerization reaction. As the (meth)acrylic acid ester monomer used to form the first block, for example, alkyl (meth)acrylate may be used. In one example, when considering the cohesive force, glass transition temperature and control of adhesiveness, etc., alkyl 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 (meta )Acrylate may be used to form the first block. 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, lauryl (meth) acrylate, and the like. In order to secure the glass transition temperature range, among the monomers One or more may be used to form the first block.

In one example, in consideration of the ease of controlling the glass transition temperature, an alkyl methacrylate 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. I can. Although not particularly limited, in consideration of reactivity during polymerization, for example, the first block is a polymerization unit derived from 60 to 80 parts by weight of an alkyl methacrylate having an alkyl group having 1 to 3 carbon atoms, and 4 to 10 carbon atoms. It may contain a polymerization unit derived from 20 to 40 parts by weight of an alkyl methacrylate having an alkyl group of. In the present application, the term "parts by weight" may mean a weight ratio between each component. For example, from 60 to 80 parts by weight of an alkyl methacrylate (A) having an alkyl group having 1 to 3 carbon atoms and 20 to 40 parts by weight of an alkyl methacrylate (B) having an alkyl group having 4 to 10 carbon atoms Including the derived polymerized unit may mean the case where the weight ratio of the monomer (A) and the monomer (B) forming the polymerized unit of the first block is in the range of 60 to 80:20 to 40.

In one example, the second block may be a polymer of (meth)acrylic acid ester monomer. Specifically, the first block may include a polymerized unit derived from a (meth)acrylic acid ester monomer and a polymerization unit derived from a copolymerizable monomer having a crosslinkable functional group. The content of the monomer used to form the second block is not particularly limited, but, for example, the second block includes 80 to 99.9 parts by weight of a (meth)acrylic acid ester monomer and 0.1 to 20 copolymerizable monomers having a crosslinkable functional group. It may contain a polymerization unit derived from parts by weight.

In one example, in consideration of the ease of controlling the glass transition temperature, among the (meth)acrylic acid ester monomers described above, among the above-described (meth)acrylic acid ester monomers, there are 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to carbon atoms. Alkyl acrylate having an alkyl group of 4 may be used for forming the second block. Although not particularly limited, in consideration of reactivity during polymerization, the second block is 80 to 99.9 parts by weight of an alkyl acrylate having an alkyl group having 1 or 4 carbon atoms, and 0.1 to 20 parts by weight of a copolymerizable monomer having a crosslinkable functional group It may contain polymerized units derived from wealth. When the above composition is satisfied, a pressure-sensitive adhesive capable of minimizing light leakage while securing physical properties such as interfacial adhesion, durability reliability, and appropriate cohesive strength can be provided.

The copolymerizable monomer having a crosslinkable functional group included in the second block has a site that can be copolymerized with other monomers included in the block copolymer, such as the alkyl acrylate monomer, and the above-described crosslinking It may be a monomer having a sexual functional group. As the crosslinkable functional group contained in the copolymerizable monomer, the aforementioned hydroxy group, carboxyl group, epoxy group, isocyanate group or nitrogen-containing functional group may be used.

The monomer having a crosslinkable functional group as described above is variously known in the field of pressure-sensitive adhesive manufacturing, and a known monomer may be used without limitation. For example, when the copolymerizable monomer having a crosslinkable functional group is a monomer having a hydroxy group, As such a monomer, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate or 8 -Hydroxyalkyl (meth)acrylates such as hydroxyoctyl (meth)acrylate; Or hydroxyalkylene glycol (meth)acrylate, such as 2-hydroxyethylene glycol (meth)acrylate or 2-hydroxypropylene glycol (meth)acrylate; examples thereof include, but are limited thereto. It does not become.

The first block and/or the second block may additionally include an arbitrary comonomer as needed, for example, for controlling a glass transition temperature, and the monomer may be included as a polymerization unit. As the comonomer, (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; 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 included in the polymer by selecting one or more types of appropriate types as necessary. Such comonomers 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 in each block.

In one example, the block copolymer may include 5 parts by weight to 50 parts by weight of the first block and 50 parts by weight to 95 parts by weight of the second block. By controlling the ratio of the weight between the first block and the second block as described above, it is possible to provide an adhesive composition and an adhesive having excellent physical properties.

In one example, the block copolymer may be a diblock copolymer including the first and second blocks, that is, a block copolymer including only two blocks of the first block and the second block. have. By using the diblock copolymer, it is possible to excellently maintain the interfacial adhesion, durability reliability, stress relaxation property, and reworkability of the pressure-sensitive adhesive.

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, anionic polymerization synthesized in the presence of an inorganic acid salt such as an alkali metal or alkaline earth metal salt by using an organic rare earth metal complex as a polymerization initiator or an organic alkali metal compound as a polymerization initiator, or an organic alkali metal compound initiated polymerization Anionic polymerization method that uses zero to synthesize in the presence of organic aluminum compounds, atomic transfer radical polymerization (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, but generates electrons ARGET (Activators Regenerated by Electron Transfer) atom transfer radical polymerization method (ATRP), ICAR (Initiators for continuous activator regeneration) atom transfer radical polymerization method (ATRP), inorganic reducing agent reversible addition-cleavage Polymerization by reversible addition-cleavage chain transfer using a chain transfer agent (RAFT), or a method using an organic tellurium compound as an initiator may be used, and an appropriate method may be selected from among the above methods to prepare the block copolymer. have.

The adhesive composition of the present application may include at least one crosslinking agent capable of forming a chemical crosslinking structure by reacting with a crosslinkable functional group of the block copolymer. As the crosslinking agent, a multifunctional crosslinking agent having two or more functional groups capable of reacting with a crosslinkable functional group contained in the block copolymer may be used. Non-limiting examples of such a crosslinking agent include an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, or a metal chelate crosslinking agent.

In one example, when the crosslinkable functional group is a hydroxy group, an isocyanate crosslinking agent may be used as the multifunctional crosslinking agent. The type of the isocyanate crosslinking agent is not particularly limited, but for example, tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isoboro diisocyanate, tetramethylxylene diisocyanate or naphthalene diisocyanate. Diisocyanate compounds; Alternatively, a compound obtained by reacting the diisocyanate compound with a polyol; can be used. Trimethylol propane may be used as the polyol.

In one example, the multifunctional crosslinking agent may be included in the adhesive composition in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the block copolymer. More specifically, the lower limit of the content of the crosslinking agent may be 0.03 parts by weight or more, 0.05 parts by weight or more, or 0.10 parts by weight or more, and the upper limit may be 5 parts by weight or less, 3 parts by weight or less, or 1.0 parts by weight or less. In this range, the degree of crosslinking of the block copolymer may be appropriately adjusted, and through this, the gel fraction, cohesion, adhesion, and durability of the adhesive may be excellently maintained.

The adhesive composition of the present application may use two types of silane coupling agents at the same time. The silane coupling agent is known as the most widely used coupling agent, but when an excessive amount of silane coupling agent is used, bubbles are generated at the adhesive interface under severe conditions such as high temperature or high humidity conditions, and peeling or lifting occurs as the adhesive strength decreases. Is observed. As a result, there is a problem that the heat resistance and moisture heat resistance of the product are deteriorated, and as a result, the light leakage phenomenon is increased. Therefore, in the prior art, in consideration of the above problems, even if a silane coupling agent is used, it has been common to use an extremely small amount of only one type.

In contrast, the pressure-sensitive adhesive composition of the present application may include two types of silane coupling agents having different functional groups in a specific content range. Specifically, the pressure-sensitive adhesive composition of the present application may simultaneously include a first silane coupling agent (A) having an isocyanate group and a second silane coupling agent (B) having a functional group other than an isocyanate group. At this time, the first silane coupling agent (A) may include only an isocyanate group as a functional group in addition to an alkoxy group, and the second silane coupling agent (B) may include a functional group mentioned below except for an isocyanate group.

The first silane coupling agent (A) has an effect of binding the silane coupling agent to the block copolymer by bonding the isocyanate group contained in the first silane coupling agent to the crosslinkable functional group of the block copolymer. Since the binding by the first silane coupling agent occurs at a faster rate than the binding of the block copolymer with the second silane coupling agent (B) having a functional group other than an isocyanate group, the present application further enhances the effect of the introduction of the silane coupling agent. It can be improved. As mentioned above, in the case of the second silane coupling agent (B), when used in excess, the excess silane coupling agent bleeds to the pressure-sensitive adhesive surface, thereby reducing durability and reliability. However, as in the present application, when the first silane coupling agent (A) is used in a specific content range mentioned below, the silane coupling agent bound to the block copolymer may more effectively adhere to the pressure-sensitive adhesive and the glass substrate. Therefore, compared to the case where the second silane coupling agent (B) having a functional group other than an isocyanate group is used alone, higher adhesion and adhesion stability can be expressed under heat and moist heat resistance conditions, and durability reliability under heat and moist heat resistance is improved. I can.

In one example, the first silane coupling agent (A) is, for example, a compound containing an isocyanate group and one or more alkoxy groups, such as 3-isocyanatepropyl triethoxy silane, or 3-isocyanate propyl trimethoxy silane. Can be The first silane coupling agent (A) may be represented by Formula 1 below.

[Formula 1]

In Formula 1, R ₁ to R ₃ may each independently be a hydroxy group, an alkoxy group having 1 to 20 carbon atoms, or an alkyl group having 1 to 20 carbon atoms, and at least one of R ₁ to R ₃ may have 1 to 20 is an alkoxy group, A is an alkylene group, and R ₄ is an isocyanate group. In one example, A may be an alkylene group having 1 to 10 carbon atoms.

In one example, the alkoxy group may be a straight chain, branched chain or cyclic alkoxy group, and the alkyl group bonded with oxygen of the alkoxy group has 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or It may be an alkyl group having 1 to 4 carbon atoms.

In one example, the first silane coupling agent (A) may be included in a range of 0.01 to 10 parts by weight based on 100 parts by weight of the block copolymer. Specifically, the lower limit of the content of the first silane coupling agent may be 0.01 parts by weight, 0.1 parts by weight, 0.5 parts by weight, 1 part by weight, or 3 parts by weight or more, and the upper limit is 10 parts by weight, 5 parts by weight, or 1.5 parts by weight. It can be wealth.

The second silane coupling agent (B) may be a compound having a functional group other than an isocyanate group. For example, the second silane coupling agent (B) may include 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 element.

In one example, as the second silane coupling agent (B), a compound having a beta-cyano group represented by the following formula (2) or a compound having an acetoacetyl group represented by the following formula (3) may be used.

[Formula 2]

(R ₅ ) _n Si(R ₆ ) _(4-n)

[Formula 3]

(R ₇ ) _n Si(R ₆ ) _(4-n)

In Formula 2 or 3, R ₅ is a beta-cyanoacetyl group or a beta-cyanoacetylalkyl group, R ₇ is an acetoacetyl group or an acetoacetylalkyl group, R ₆ is an alkoxy group, and n is of 1 to 3 It's a number.

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 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 2 or 3 include acetoacetylpropyl trimethoxy silane, acetoacetylpropyl triethoxy silane, beta cyanoacetylpropyl trimethoxy silane, or beta cyanoacetylpropyl triethoxy silane. However, it is not particularly limited thereto.

In one example, the second silane coupling agent (B) may be included in the range of 0.01 to 10 parts by weight based on 100 parts by weight of the block copolymer. Specifically, the lower limit of the content of the second silane coupling agent may be 0.01 parts by weight or more, 0.1 parts by weight, or 0.2 parts by weight or more, and the upper limit is 10 parts by weight or less, 5 parts by weight or less, 3 parts by weight or less, or 1 part by weight. It may be less than or equal to part.

In one example, the content ratio (A/B) of the first silane coupling agent (A) and the second silane coupling agent (B) may be controlled in the range of 2 to 30. When the content ratio (A/B) is less than 2, the effect of the addition of the first silane coupling agent is insignificant, it is difficult to obtain an effect of improving durability reliability under severe conditions, and when the content ratio (A/B) exceeds 30 , Since the isocyanate group of the first silane coupling agent (A) participates in crosslinking, overcuring may occur and durability may decrease.

The adhesive composition may further contain 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 a mixture of two or more kinds, such as a polymerized rosin ester resin, may be used, but is not limited thereto. The tackifier may be included in the adhesive composition in an amount of 100 parts by weight or less based on 100 parts by weight of the block copolymer.

In addition, the adhesive composition may further include additives such as an epoxy resin, a curing agent, an ultraviolet stabilizer, an antioxidant, a colorant, a reinforcing agent, a filler, an antifoaming agent, a surfactant, or a plasticizer. The specific type or content of the additive is not particularly limited.

In an example related to the present application, the adhesive composition may be an adhesive composition for an optical film. The adhesive composition for an optical film is, for example, a polarizing film, a retardation film, an anti-glare film, a wide viewing angle compensation film, or an optical film such as a luminance enhancing film, or the like, or the optical film or a laminate thereof, such as a liquid crystal panel. It can be used for attachment to an adherend. In one example, the adhesive composition is an adhesive composition for a polarizing plate, and may be an adhesive composition used for attaching a polarizing film to a liquid crystal panel.

In another example, the present application relates to a pressure-sensitive adhesive optical laminate. An exemplary optical laminate is an optical film; And it may include a pressure-sensitive adhesive layer present on at least one surface of the optical film. The pressure-sensitive adhesive layer may be, for example, a pressure-sensitive adhesive layer for attaching the optical film to a liquid crystal panel of an LCD device or other optical film. In addition, the pressure-sensitive adhesive layer may include the pressure-sensitive adhesive composition of the present application described above. The adhesive composition may be included in the adhesive layer while implementing a crosslinked structure. In the above, as the optical film, a polarizing plate, a polarizer, a retardation film or a brightness enhancing film, or a laminate in which two or more of the above are laminated may be exemplified. In this specification, the terms polarizer and polarizer 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.

This application also relates to an adhesive polarizing plate. The polarizing plate may have, for example, a structure in which the optical film is a polarizer in the adhesive optical laminate.

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.

The polarizing plate may further include a protective film attached to one or both surfaces of the polarizer, and in this case, the pressure-sensitive adhesive layer may be formed on one or both surfaces of the protective film. In one example, the pressure-sensitive adhesive layer may be formed on a side opposite to the polarizer of the protective film. The type of the protective film is not particularly limited, 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 layer or a two or more layered structure, such as a polyethylene film, a polypropylene film, or a polyolefin-based film manufactured using a resin having a cyclo-based or norbornene structure, or an ethylene-propylene copolymer, may be used. When considering securing moisture barrier properties, PET-based and polyolefin-based films can be used, and when securing durability is considered, acrylic-based films can be used.

The polarizing plate may further include one or more functional layers selected from the group consisting of a protective layer, a reflective layer, an antiglare 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 film is not particularly limited, and for example, a method of implementing a crosslinked structure by directly coating and curing the pressure-sensitive adhesive composition on a polarizing plate or the like, or After forming a crosslinked structure by coating and curing the adhesive composition on the release-treated surface, a method of transferring it may be used.

The method of coating the adhesive composition is not particularly limited, and for example, a method of applying the 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 crosslinking agent contained in the adhesive composition is controlled so that the crosslinking reaction of the functional group does not proceed during the coating process, and through this, the crosslinking agent improves the crosslinking structure in the curing and aging process after the coating operation. By forming, it is possible to improve the cohesiveness of the pressure-sensitive adhesive, and improve adhesion properties and cuttability.

In addition, the coating process is preferably carried out after sufficiently removing bubbles-inducing components such as volatile components or reaction residues inside the adhesive composition, and accordingly, the crosslinking density or molecular weight of the 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 also 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 multifunctional crosslinking agent may be induced.

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 and second substrates may be glass substrates. 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.

The present application, when used for an optical film, can provide an adhesive composition capable of improving durability reliability under severe conditions such as high temperature and high humidity.

Hereinafter, the adhesive composition of the present application will be described in detail through Examples and Comparative Examples. However, the scope of the present application is not limited by the following examples.

Physical properties in this Example and Comparative Example were evaluated in the following manner.

1. Molecular weight property evaluation

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. The measurement results were converted using standard polystyrene (Aglient system (manufactured)) to prepare the calibration curve.

<GPC measurement conditions>

Measuring instrument: Aglient GPC (Aglient 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 the following formula A.

<Equation A>

1/Tg=∑Wn/Tn

In the above formula, 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 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. 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 then attached to a 19-inch commercial liquid crystal panel. Thereafter, the panel to which the polarizing plate was attached was stored in an autoclave (50° C., 5 atm) for about 20 minutes to prepare a sample.

For the heat resistance durability, after leaving the sample at 80° C. for 500 hours, the occurrence of bubbles and peeling was observed and evaluated according to the following criteria.

In the case of moisture and heat resistance, the sample was allowed to stand at 60° C. and 90% relative humidity for 500 hours, and then bubbles and peeling at the adhesive interface were observed and evaluated according to the following criteria.

<Criteria for evaluating heat resistance and moisture 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

4. Evaluation of bending properties

(1) heat resistance Conditionally Bending properties

The flexural properties were evaluated using the strip measurement method (Glass bending measurement). First, a Bending STN sodalime glass (4 x 41 cm ² , 0.4t) was prepared. If there is no foreign matter, it is used as it is without washing, and if there is a foreign matter, it is washed thoroughly with EAc and IPA solvent, and then dried using an air-gun. Prepare a polarizing plate (coated product) with an adhesive in a length of 3.5 × 40.5 cm ² in the MD direction. Attach the specimen to the prepared bending glass using a laminator. After the initial value is measured, it is stored for 72 hours at 80 ℃ heat-resistant condition. Prepare a device that can fix the sample in the chamber as shown in the figure below, fix the sample on one side of the bending sample, and measure the distance away from the reference point. Three samples are prepared for the same prescription and the average value is calculated.

(2) Moist heat resistance Conditionally Bending properties

The bending properties were measured in the same manner as described above, but the samples prepared in the same manner were stored for 72 hours under moist heat resistance at 60°C and 90% relative humidity, and then the bending properties were measured.

<Picture. Measurement location of Glass Bending (Strip measurement method)>

Preparation of copolymer

Manufacturing example 1. Preparation of block copolymer (A1)

0.032 g of ethyl 2-bromoisobutyrate (EBiB) and 11.4 g of methyl methacrylate (MMA) and 2.9 g of butyl methacrylate (BMA) were mixed with 6.1 g of ethyl acetate (EAc). 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. And immersed in a reaction tank at about 67°C to initiate the reaction (polymerization of the first block). When the conversion rate of methyl methacrylate is about 70%, a mixture of 111.4 g of methyl acrylate (MA), 1.1 g of hydroxybutyl acrylate (HBA) and 75 g of ethyl acetate (EAc), previously bubbled with nitrogen It was charged 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, thereby preparing a block copolymer. In the above process, V-65 was appropriately divided and added to the end of the reaction in consideration of its half-life.

Manufacturing example 2 to 5. Preparation of block copolymers (A2 to A5)

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

Manufacturing example 6. Preparation of random copolymer (B1)

A monomer mixture consisting of 99 parts by weight of n-butylacrylate (BA) and 1.0 parts by weight of hydroxybutyl acrylate was added to a 1L reactor in which nitrogen gas was refluxed and a cooling device was installed to facilitate temperature control. . Thereafter, 150 parts by weight of ethyl acetate (EAc) was added as a solvent. After purging nitrogen gas for about 60 minutes to remove oxygen, 0.03 parts by weight of AIBN (azobisisobutyronitrile), a reaction initiator, was added while maintaining the temperature at 60° C., and reacted for about 8 hours to make a random copolymer (B3). ) Was prepared. The weight average molecular weight of the produced random copolymer (B1) was 1.2 million, and the molecular weight distribution was 5.1.

Manufacturing example 7. Preparation of random copolymer (B2)

N-butylacrylate (BA) 79.2 parts by weight, hydroxybutyl acrylate 0.8 parts by weight, styrene having a vinyl group at the terminal in a 1L reactor equipped with a cooling device to facilitate nitrogen gas reflux and temperature control (The glass transition temperature of the homopolymer is 100° C.) 20 parts by weight were added. Thereafter, 150 parts by weight of ethyl acetate (EAc) was added as a solvent. After purging nitrogen gas for about 60 minutes to remove oxygen, 0.03 parts by weight of AIBN (azobisisobutyronitrile), a reaction initiator, was added while maintaining the temperature at 60° C., and reacted for about 48 hours to make a random copolymer (B2). ) Was prepared. The weight average molecular weight of the produced random copolymer (B2) was 130,000, and the molecular weight distribution was 2.5.

Example One.

Preparation of coating solution (adhesive composition)

With respect to 100 parts by weight of the block copolymer (A1) prepared in Preparation Example 1, 0.07 parts by weight of a TDI-based crosslinking agent (Coronate L, manufactured by NPU Japan), 0.1 parts by weight of DBTDL (Dibutyltin dilaurate), and a silane coupling agent 1 having an isocyanate group A coating solution (adhesive composition) was prepared by mixing parts by weight and 0.2 parts by weight of a silane coupling agent having a beta cyanoacetyl group, 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) so that the thickness after drying is about 23 μm, and in an oven at 110° C. for about 3 minutes Maintained. 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=cyclopolyolefin, PVA=polyvinyl alcohol-based polarizing film) to prepare an adhesive polarizing plate.

Example 2 to 4 and Comparative example 1 to 6

When preparing the adhesive composition (coating solution), an adhesive composition (coating solution) and an 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.

The evaluation results of physical properties for Examples and Comparative Examples are shown in Table 3 below.

Claims (19)

A block copolymer having 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; And a silane coupling agent,
The silane coupling agent has a functional group other than the first silane coupling agent (A) having an isocyanate group and an isocyanate group, and contains any one of an epoxy group, a thiol group, an amino group, a vinyl group, a beta-cyano group, an acetoacetyl group, or a halogen element. It includes a second silane coupling agent (B),
The pressure-sensitive adhesive composition in which the content ratio (A/B) of the first silane coupling agent (A) and the second silane coupling agent (B) is 2 to 30. delete delete delete The adhesive composition of claim 1, wherein the first silane coupling agent (A) and the second silane coupling agent (B) are included in an amount of 0.01 to 10 parts by weight, respectively, based on 100 parts by weight of the block copolymer. The adhesive composition of claim 1, wherein the first silane coupling agent (A) is represented by the following Formula 1:
[Formula 1]

In Formula 1, R ₁ to R ₃ may each independently be a hydroxy group, an alkoxy group having 1 to 20 carbon atoms, an alkyl group having 1 to 20 carbon atoms, and at least one of R ₁ to R ₃ may be a C 1 to C 20 group. It is an alkoxy group, A is an alkylene group, and R ₄ is an isocyanate group. The adhesive composition of claim 1, wherein the block copolymer comprises 5 to 50 parts by weight of the first block and 50 to 95 parts by weight of the second block. The adhesive composition of claim 1, wherein the first block contains a polymerized unit derived from a (meth)acrylic acid ester monomer. The adhesive composition of claim 1, wherein the second block contains a crosslinkable functional group. The adhesive composition of claim 1, wherein the second block comprises a polymerization unit derived from 80 to 99.9 parts by weight of a (meth)acrylic acid ester monomer and 0.1 to 20 parts by weight of a crosslinkable functional group-containing monomer. The adhesive composition according to any one of claims 9 to 10, wherein the crosslinkable functional group is a hydroxy group, a carboxyl group, an epoxy group, an isocyanate group, or a nitrogen-containing functional group. The adhesive composition of claim 1, wherein the first block has a number average molecular weight (Mn) of 2,500 to 150,000. The adhesive composition of claim 12, wherein the block copolymer has a number average molecular weight (Mn) of 50,000 to 300,000. The adhesive composition according to claim 13, wherein 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 2.5. The adhesive composition of claim 1, wherein the block copolymer is a diblock copolymer composed of the first block and the second block. The pressure-sensitive adhesive composition according to claim 1, wherein the polyfunctional crosslinking agent is included in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the block copolymer. An optical film, and a pressure-sensitive adhesive layer provided on at least one surface of the optical film and comprising the pressure-sensitive adhesive composition according to claim 1. A polarizing plate and a pressure-sensitive adhesive polarizing plate provided on at least one surface of the polarizing plate and having a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive composition according to claim 1. A display device comprising a liquid crystal panel and the adhesive optical laminate according to claim 17 or the adhesive polarizing plate according to claim 18 provided on at least one surface of the liquid crystal panel.