KR102079139B1 - Pressure sensitive adhesive composition - Google Patents

Abstract

The present application relates to an adhesive composition, an optical laminate, an adhesive polarizing plate, and a display device. In the present application, a pressure-sensitive adhesive composition having excellent physical properties such as durability reliability and interfacial adhesion may be provided. The pressure-sensitive adhesive composition of the present application can be used, for example, for an optical film such as a protective film or a polarizing plate.

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 referred to as "LCD device") usually includes a liquid crystal panel and an optical film containing a liquid crystal component injected between two transparent substrates. Examples of the optical film include a polarizing film, a retardation film, or a brightness-enhancing film, and in many cases, an adhesive for an optical film is used to laminate the optical films or to attach the optical film to an adherend such as a liquid crystal panel. As the pressure-sensitive adhesive, there are those using an acrylic polymer, rubber, urethane resin, silicone resin or ethylene vinyl acetate (EVA) resin, etc., and the optical film, especially the pressure-sensitive adhesive for polarizing plates, has excellent transparency and resistance to oxidation and yellowing. Adhesives comprising a copolymer are generally used.

The main properties required for the pressure-sensitive adhesive composition for optical films include cohesion, adhesion, reworkability, low light leakage properties and stress relaxation. In Patent Documents 1 to 3, an adhesive composition for achieving the above properties has been proposed.

Patent Document 1: Republic of Korea Patent No. 1023839 Patent Document 2: Republic of Korea Registered Patent No. 1171976 Patent Document 3: Republic of Korea Registered Patent No. 1171977

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

This application relates to an adhesive composition. Exemplary pressure-sensitive adhesive composition may include a block copolymer. As used herein, the term "block copolymer" may refer to 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 specification, "the glass transition temperature of a predetermined block" of a block copolymer may mean a glass transition temperature measured from a polymer formed only of monomers included in the block.

In one example, the glass transition temperature of the first block may be 60 ° C or higher, 65 ° C or higher, 70 ° C or higher, or 75 ° C or higher. The upper limit of the glass transition temperature of the first block is not particularly limited, and may be, for example, about 150 ° C, 140 ° C, 130 ° C, or 120 ° C.

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

The copolymer containing at least the two types of blocks may form a fine phase separation structure in the adhesive. Such a block copolymer can form a pressure-sensitive adhesive that exhibits appropriate cohesive force and stress relaxation property according to temperature change, and maintains excellent physical properties required in an optical film such as durability reliability, light leakage preventing property, and reworkability.

In one example, the first block of the block copolymer may have, for example, a number average molecular weight (Mn: 2,500 to 150,000). The number average molecular weight of the first block may mean, for example, a number average molecular weight of the polymer produced by polymerizing only the monomers forming the first block. The number average molecular weight referred to in this specification can be measured by the method presented in Examples using, for example, GPC (Gel Permeation Chromatograph). The lower limit of the number average molecular weight of the first block may be, for example, 2,500 or more, 3,000 or more, 4,000 or more, 5,000 or more, 6,000 or more, 7,000 or more, 8, 000 or more, 9,000 or more, or 10,000 or more. The upper limit of the number average molecular weight of the first block may be, for example, 150,000 or less, 140,000 or less, 130,000 or less, 120,000 or less, 11,000 or less, 10,000 or less, 9,000 or less, 8,000 or less, 7,000 or less, 6,000 or less, or 5,000 or less. In one example, the block copolymer may have a number average molecular weight of 50,000 to 300,000. The lower limit of the number average molecular weight of the block copolymer may be, for example, 50,000 or more, 60,000 or more, 70,000 or more, 80,000 or more, or 90,000 or more. The upper limit of the number average molecular weight of the block copolymer may be, for example, 300,000 or less, 280,000 or less, 260,000 or less, 240,000 or less, 220,000 or less, 200,000 or less, or 180,000 or less. In one example, the block copolymer may have a molecular weight distribution (PDI; Mw / Mn), that is, a ratio (Mw / Mn) of a weight average molecular weight (Mw) and a number average molecular weight (Mn) in the range of 1.0 to 2.5. The lower limit of the molecular weight distribution of the block copolymer may be, for example, 1,0 or more, 1.1 or more, 1.2 or more, 1.3 or more, 1.4 or more, 1.5 or more, or 1.6 or more. The upper limit of the molecular weight distribution of the block copolymer may be, for example, 2.5 or less, 2.4 or less, 2.3 or less, 2.2 or less, 2.1 or less, 2.0 or less, 1.9 or less, 1.8 or less, or 1.7 or less. The molecular weight properties can be adjusted as described above to provide a pressure-sensitive adhesive composition or pressure-sensitive adhesive having excellent physical properties.

The block copolymer may be a crosslinkable copolymer having a crosslinkable functional group. As a crosslinkable functional group, a hydroxyl group, a carboxyl group, an isocyanate group, a glycidyl group, etc. can be illustrated. In one example, the crosslinkable functional group of the block copolymer may be a hydroxy group.

When a crosslinkable functional group is included, the functional group may be included in, for example, a block having a relatively low glass transition temperature, that is, a second block. In one example, the crosslinkable functional group is not included in the first block, but may be included only in the second block. When the crosslinkable functional group is included in the second block, it is possible to form a pressure-sensitive adhesive exhibiting appropriate cohesive force and stress relaxation property according to temperature change, thereby maintaining excellent physical properties such as durability reliability, light leakage prevention properties, and reworkability.

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

In one example, the first block may include polymerized units derived from (meth) acrylic acid ester monomers. The presence of a monomer in a polymer or a block as a polymerized unit in the present specification may mean that the monomer undergoes a polymerization reaction to form a skeleton, for example, a main chain or a side chain, of the polymer or block. As said (meth) acrylic acid ester monomer, alkyl (meth) acrylate can be used, for example. In consideration of cohesion, glass transition temperature, and adjustment of adhesion, an alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms is used. Can be used. In the above, the alkyl group may be linear, branched or cyclic. Examples of such monomers are methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) ) Acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, n-octyl (meth) acrylate, iso Bornyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate and lauryl (meth) acrylate, and the like, and the glass transition temperature of one or more of the above is secured You can choose and use as much as possible. As a monomer forming the first block in consideration of the ease of adjusting the glass transition temperature, etc., among the monomers, a methacrylic acid ester monomer such as alkyl methacrylate, for example, 1 to 20 carbon atoms, 1 to 16 carbon atoms, carbon number Alkyl methacrylate having an alkyl group having 1 to 12, 1 to 8, or 1 to 4 carbon atoms can be used.

The second block may include, for example, polymerized units derived from 60 parts by weight to 99 parts by weight of the (meth) acrylic acid ester monomer and 1 part by weight to 40 parts by weight of the copolymerizable monomer having a crosslinkable functional group. In the present specification, the unit weight part may mean a ratio of weight between each component. For example, as described above, the second block contains 90 parts by weight to 99.9 parts by weight of (meth) acrylic acid ester monomer and polymerized units derived from 0.1 parts by weight to 10 parts by weight of a copolymerizable monomer having a crosslinkable functional group. The ratio (A: B) based on the weight of the (meth) acrylic acid ester monomer (A) forming the polymerized unit of the second block and the copolymerizable monomer (B) having a crosslinkable functional group is 90 to 99.9: It may mean a case of 0.1 to 10.

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

As a copolymerizable monomer having a crosslinkable functional group, for example, it has a site that can be copolymerized with other monomers included in the block copolymer, such as the (meth) acrylic acid ester monomer, and also has the crosslinkable functional group described above. By using a monomer, the pressure-sensitive adhesive can exhibit an appropriate cohesive force and stress relaxation property according to a change in temperature, thereby forming a pressure-sensitive adhesive having excellent durability reliability, light leakage preventing properties, workability, and the like. In one example, a copolymerizable monomer having a hydroxyl group may be used as the copolymerizable monomer having the crosslinkable functional group. Accordingly, the second block may include 60 to 99 parts by weight of a (meth) acrylic acid ester monomer and 1 to 40 parts by weight of a copolymerizable monomer having a hydroxyl group.

In the manufacturing field of the pressure-sensitive adhesive, various copolymerizable monomers having such crosslinkable functional groups are known, and all such monomers can be used in the polymer. For example, as a copolymerizable monomer having a hydroxy group, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxy Hydroxyalkyl (meth) acrylates such as hexyl (meth) acrylate or 8-hydroxyoctyl (meth) acrylate, or 2-hydroxyethylene glycol (meth) acrylate or 2-hydroxypropylene glycol (meth) Hydroxyalkylene glycol (meth) acrylate such as acrylate may be used, but is not limited thereto. In consideration of reactivity with other monomers forming the second block or ease of adjustment of the glass transition temperature, hydroxyalkyl acrylate or hydroxyalkylene glycol acrylate may be used among the monomers described above, but is not limited thereto. no.

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

The block copolymer may include, for example, 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 adjusting 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 another example, the block copolymer is 5 parts to 45 parts by weight of the first block and 55 parts to 95 parts by weight of the second block or 5 parts to 45 parts by weight of the first block and 60 parts by weight of the second block 95 parts by weight.

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 and second blocks. . By using a diblock copolymer, the durability of the pressure-sensitive adhesive, stress relaxation and reworkability, etc. can be excellently maintained.

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

The pressure-sensitive adhesive composition may include a crosslinking agent capable of crosslinking the block copolymer. The crosslinking agent may implement a crosslinking structure by reacting with the crosslinking point of the block copolymer, that is, the aforementioned crosslinkable functional group. As the crosslinking agent, a crosslinking agent having at least two functional groups capable of reacting with the crosslinkable functional group included in the block copolymer may be used.

In one example, toluene diisocyanate-based crosslinking agent may be used as the crosslinking agent. Since the toluene diisocyanate-based crosslinking agent has a slow reaction rate with a hydroxy group compared to other isocyanate-based crosslinking agents, the content of the crosslinking agent remaining after coating is high, and thus, reaction with the adherend occurs to maintain excellent interfacial adhesion.

 In one example, the toluene diisocyanate-based crosslinking agent may include two or more isocyanate groups bonded to toluene. For example, the toluene diisocyanate-based crosslinking agent has two or more toluene molecules, for example, two or more isocyanate group-bonded compounds, or two or more toluene molecules with one isocyanate group bonded structure, for example, It may mean a compound containing three.

In one example, the toluene diisocyanate-based crosslinking agent may include at least one selected from the group consisting of toluene diisocyanate, a multimer of toluene diisocyanate, and a reactant of a polyhydric alcohol and toluene diisocyanate. Multimers of toluene diisocyanate may include dimers or trimers of toluene diisocyanate. As the trimer of the toluene diisocyanate, for example, the remaining 1 mole of toluene diisocyanate in toluene diisocyanate urea obtained from 2 moles of isocyanurate body or 3 moles of toluene diisocyanate obtained by self-condensing 3 moles of toluene diisocyanate. A condensed burette can be used. As a reactant of the polyhydric alcohol and toluene diisocyanate, for example, an adduct obtained by reacting 3 moles of toluene diisocyanate with 1 mole of trimethylolpropane can be used. In the pressure-sensitive adhesive composition, one or two or more types of crosslinking agents may be used, but the present invention is not limited thereto, and toluene diisocyanate-based crosslinking agents known in the art may be used.

The toluene diisocyanate-based crosslinking agent may be included in the pressure-sensitive adhesive composition in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the block copolymer. The lower limit of the content of the crosslinking agent is, for example, 0.05 parts by weight or more, 0.1 parts by weight or more, 0.15 parts by weight or more, 0.2 parts by weight or more, 0.25 parts by weight or more, 0.3 parts by weight or more, 1 part by weight or more, 2 parts by weight Or more, 3 parts by weight or more, or 4 parts by weight or more. The upper limit of the crosslinking agent content may be, for example, 10 parts by weight or less, 8 parts by weight or less, 6 parts by weight or less, 4 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, 0.75 parts by weight or less, or 0.5 parts by weight or less You can. In this range, the crosslinking degree of the block copolymer can be appropriately adjusted, and through this, it is possible to maintain excellent physical properties such as gel fraction, cohesion, adhesion, durability and interfacial adhesion of the adhesive.

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

As a silane coupling agent having a beta-cyano group or acetoacetyl group, for example, a compound represented by the following formula 1 or 2 can be used.

 [Formula 1]

(R ₆ ) _n Si (R ₇ ) _(4-n)

 [Formula 2]

(R ₈ ) _n Si (R ₆ ) _(4-n)

In Formula 1 or 2, R ₆ is a beta-cyanoacetyl group or a beta-cyanoacetylalkyl group, R ₈ is an acetoacetyl group or acetoacetylalkyl group, R ₇ is an alkoxy group, and n is 1 to 3 Sue.

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

As the compound of Formula 1 or 2, for example, acetoacetylpropyl trimethoxy silane, acetoacetylpropyl triethoxy silane, beta-cyanoacetylpropyl trimethoxy silane or beta-cyanoacetylpropyl triethoxy silane And the like, but is not limited thereto.

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

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

The pressure-sensitive adhesive composition, if necessary, known additives, for example, a coordination-binding compound capable of forming a coordination bond with the antistatic agent, an epoxy resin, a curing agent, a UV stabilizer, an antioxidant, a colorant, a reinforcing agent, a filler, an antifoaming agent, It may further include one or more additives selected from the group consisting of surfactants and plasticizers.

The present application also relates to the use of the pressure-sensitive adhesive composition.

The pressure-sensitive adhesive composition may be a pressure-sensitive adhesive composition for a protective film. The protective film may be used, for example, for protecting a surface of various optical films.

The pressure-sensitive adhesive composition may be a pressure-sensitive 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 brightness enhancing film, or the like, or the optical film or a laminate thereof such as a liquid crystal panel. It can be used for the purpose of attaching to the adherend. In one example, the pressure-sensitive adhesive composition may be a pressure-sensitive adhesive composition used for attaching a polarizing film to a liquid crystal panel as the pressure-sensitive adhesive composition for a polarizing plate.

In one example, the present application relates to a pressure-sensitive adhesive optical laminate. Exemplary optical laminates include: optical films; And it may include a pressure-sensitive adhesive layer present on one or both sides 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 pressure-sensitive adhesive composition may be included in the pressure-sensitive adhesive layer in a state in which a crosslinked structure is implemented. In the above, as the optical film, a polarizing plate, a polarizer, a retardation film, a brightness enhancing film, or the like, or a laminate in which two or more kinds are laminated among the above 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 element itself that exhibits a polarization function, and the polarizer refers to an optical element including other elements together with the polarizer. As other elements that may be included in the optical element together with the polarizer, a polarizer protective film or a retardation layer may be exemplified, but is 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 the polarizer included in the polarizing plate is not particularly limited, and for example, a general type known in the field, such as a polyvinyl alcohol-based polarizer, can be employed without limitation.

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

The polarizer stretches (ex. Uniaxially stretches) the polyvinyl alcohol-based resin film as described above, dyes the polyvinyl alcohol-based resin film with a dichroic dye, adsorbs the dichroic dye, and adsorbs the dichroic dye. The prepared polyvinyl alcohol-based resin film may be prepared through a process of treating with a boric acid aqueous solution and a process of washing with water after treating with a boric acid aqueous solution. In the above, as the dichroic dye, iodine or 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 the opposite side of the polarizer of the protective film. The type of the protective film is not particularly limited, and for example, cellulose-based films such as TAC (Triacetyl cellulose); Polyester film such as polycarbonate film or PET (poly (ethylene terephthalet)); Polyether sulfone-based films; Or a polyethylene film, a polypropylene film or a resin having an cyclo- or norbornene structure or a polyolefin-based film produced using an ethylene-propylene copolymer, or the like, or a film having a laminated structure of two or more layers may be used.

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

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

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

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

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

The method of realizing the crosslinked structure by curing the pressure-sensitive adhesive composition is also not particularly limited, and for example, a method of maintaining the coating layer at an appropriate temperature so that a crosslinking reaction between the block copolymer contained in the coating layer and the multifunctional crosslinking agent may be induced. And the like.

The present application also relates to a display device, for example an LCD device. Exemplary above-mentioned optical laminate or polarizing plate may be included. 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 surfaces of the liquid crystal panel. The polarizing plate or the optical laminate may be attached to the liquid crystal panel by the above-described pressure-sensitive adhesive.

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 glass substrates. In this case, the polarizing plate or the optical laminate may be attached to the glass substrate via the above-described pressure-sensitive adhesive layer.

The device may further include a light source on a side opposite to the viewer side of the liquid crystal panel. On the first substrate on the light source side, for example, an active driving circuit including a thin film transistor (TFT), wiring, or the like as a driving element electrically connected to the transparent pixel electrode may be formed. The pixel electrode includes, for example, ITO (Indium Tin Oxide), 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.

As the liquid crystal panel in the device, for example, 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 panel such as a two-terminal or three-terminal type; All well-known panels, such as an in-plane switching (IPS) panel and a vertical alignment (VA) panel, can be applied.

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

In the present application, a pressure-sensitive adhesive composition having excellent physical properties such as durability reliability and interfacial adhesion may be provided. The pressure-sensitive adhesive composition of the present application can be used, for example, for an optical film such as a protective film or a polarizing plate.

Hereinafter, the pressure-sensitive adhesive composition will be described in detail through examples and comparative examples, but the scope of the pressure-sensitive adhesive composition is not limited by the following examples.

The 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) were measured using GPC (Gel Permeation Chromatograph), and the GPC measurement conditions are as follows. For the production of the calibration curve, measurement results were converted using standard polystyrene (Aglient system (manufactured)).

<GPC measurement conditions>

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

Column: 2 PL Mixed B connections

Column temperature: 40 ℃

Eluent: THF (Tetrahydrofuran)

Flow rate: 1.0 mL / min

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

2. TAC interface adhesion evaluation

Sample preparation and measurement methods

① Cut the PET (Poly (ethylene terephtalate)) film to a size of 2.5 X 20 cm and treat it with corona.

② After cutting the polarizing plates prepared in Examples and Comparative Examples to 2.5 X 10 cm within 1 hour, the polarizing plates are attached to the corona-treated PET film through the adhesive layer. As shown in Figure 1 below, half of the corona-treated PET film is attached to the pressure-sensitive adhesive layer of the polarizing plate.

Figure 1. Sample for evaluation of interface adhesion

③ After attaching the double-sided tape to the glass substrate, attach the polarizer part of the sample in Figure 1.

Interfacial adhesion was evaluated 5 days after the sample was prepared. The interfacial adhesion was evaluated by pulling the portion of the PET film without the polarizing plate attached and measuring the peeling force. The peel force (dyne / 25mm) was measured under the conditions of a peeling speed of 300mm / min and a peeling angle of 180 at room temperature. When the peeling force was 3000 gf or more, it was judged that the interfacial adhesion was excellent.

3. Evaluation of durability

The polarizing plates prepared in Examples and Comparative Examples were cut to have a width of 180 mm and a length of 320 mm, and attached to a 19-inch commercial liquid crystal panel. Thereafter, the panel to which the polarizing plate is attached is stored in an autoclave (50 ° C., 5 atmospheres) for about 20 minutes to prepare a sample. The heat and moisture resistance was evaluated by the following criteria by observing the occurrence of bubbles and peeling at the adhesive interface after leaving the prepared sample at 60 ° C and 90% relative humidity for 500 hours, and the heat resistance was 80 ° C. After maintaining at 500 hours, the occurrence of bubbles and peeling was also observed and evaluated according to the following criteria.

<Evaluation criteria>

A: No bubbles and peeling occurred

B: Some bubbles and / or peeling occurred

C: A large amount of air bubbles and / or peeling occurred

4. Calculation of 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.

<Formula>

1 / Tg = ∑Wn / Tn

In the above formula, Wn is a weight fraction of a block copolymer or a monomer applied to each block of the copolymer, and Tn represents a glass transition temperature when each corresponding monomer forms a homopolymer. That is, in the above formula, the right side calculates the weight fraction of the monomers used as the glass transition temperature (wn / Tn) divided by the monomers when the monomers form a homopolymer, and then sums the calculated values. to be.

Manufacturing example  1. Preparation of block copolymer (A1)

As a monomer forming the first block, 14.2 g of methyl methacrylate (MMA) and 0.1 g of ethyl 2-bromoisobutyrate (EBiB) were mixed with 6.2 g of ethyl acetate (EAc). The flask containing the mixture was sealed with a rubber membrane, nitrogen purged and stirred at about 25 ° C. for about 30 minutes, and dissolved oxygen was removed through bubbling. Then, 0.005 g of CuBr ₂ 0.002 g TPMA (tris (2-pyridylmethyl) amine) and 0.017 g of V-65 (2,2'-azobis (2,4-dimethyl valeronitrile)) were added to the deoxygenated mixture. Then, the reaction was initiated by immersion in a reaction tank at about 67 ° C (polymerization of the first block).

At a time when the conversion rate of methyl methacrylate was about 75%, a mixture forming a second block previously bubbled with nitrogen was introduced in the presence of nitrogen. The mixture forming the second block was prepared by dissolving 155 g of butyl acrylate (BA) and 0.8 g of hydroxybutyl acrylate (HBA) as a monomer mixture in 250 g of ethyl acetate (EAc) as a solvent. Then, CuBr ₂ was added to the reaction flask. 0.006 g, TPMA 0.012 g and V-65 0.005 g were added, and chain extention reaction was performed (polymerization of the second block). When the conversion rate of the monomer (BA) reached 80% or more, a block copolymer was prepared by exposing the reaction mixture to oxygen and diluting it in a suitable solvent to terminate the reaction (in the process, V-65 considered its half-life) The reaction was appropriately divided until the end of the reaction.).

Manufacturing example  2 to 7. Preparation of block copolymers (A2 to A4 and B1 to B3)

The types of raw materials and additives used in the polymerization of the first block are adjusted as shown in Table 1 below, and the types of raw materials and additives used in the polymerization of the second block are adjusted as shown in Table 2 below. In the same manner as in Production Example 1, a block copolymer was prepared.

Raw material EBiB EA CuBr ₂ TPMA V-65 MMA BMA HPMA BL
rock
zero
medium
synthesis
sieve A1 14.2 - - 0.1 6.2 0.02 0.005 0.017 A2 11.2 2.8 - 0.08 6.1 0.02 0.005 0.016 A3 9.4 6.3 - 0.07 6.8 0.02 0.005 0.016 A4 35.8 15.3 - 0.1 22 0.08 0.016 0.055 B1 11.6 2.4 0.4 0.08 6.2 0.02 0.005 0.016 B2 11.6 2.4 0.4 0.08 6.2 0.02 0.005 0.016 B3 5.8 - - 0.1 2.5 0.01 0.002 0.007 Content unit: g
MMA: methyl methacrylate (homopolymer Tg: about 110 ℃)
BMA: butyl methacrylate (homopolymer Tg: about 27 ℃)
HPMA: 2-hydroxypropyl methacrylate (homopolymer Tg: about 26 ℃)
EBiB: ethyl 2-bromoisobutyrate
EA: Ethyl acetate
TPMA: Tris (2-pyridylmethyl) amine
V-65: 2,2'-azobis (2,4-dimethyl valeronitrile)

Raw material EA CuBr ₂ TPMA V-65 BA HBA BL
rock
zero
medium
synthesis
sieve A1 115 0.8 250 0.006 0.01 0.05 A2 151 4.7 250 0.006 0.01 0.05 A3 146 9.3 250 0.006 0.01 0.05 A4 113 5.9 234 0.0002 0.0004 0.047 B1 156 - 250 0.006 0.01 0.05 B2 151 4.7 250 0.006 0.01 0.05 B3 163 0.8 250 0.006 0.01 0.05 Content unit: g
BA: butyl acrylate (homopolymer Tg: about -45 ℃)
HBA: 4-hydroxybutyl acrylate (homopolymer Tg: about -80 ℃)
EA: Ethyl acetate
TPMA: Tris (2-pyridylmethyl) amine
V-65: 2,2'-azobis (2,4-dimethyl valeronitrile)

The properties of each block copolymer prepared in the above manner are shown in Table 3 below.

Block copolymer A1 A2 A3 A4 B1 B2 B3 My
One
block MMA ratio 100 80 60 70 81 81 100 BMA ratio 0 20 40 30 16 16 0 HPMA ratio 0 0 0 0 3 3 0 Tg (℃) 110 90 72 80 90 90 110 Mn (× 10000) 1.9 2.3 2.9 3.8 2.3 2.3 0.8 PDI 1.27 1.34 1.38 1.41 1.36 1.36 1.18 2nd
block BA ratio 99.5 97.0 94.0 95.0 100.0 97.0 99.5 HBA ratio 0.5 3.0 6.0 5.0 0.0 3.0 0.5 Tg (℃) -47 -46.2 -47.5 -47.0 -45 -46.2 -47.0 block
Public
coalescence Mn (× 10000) 10.6 12.3 14.1 10.4 12.4 12.2 10.1 PDI 1.7 1.8 2.1 2.1 1.8 1.8 1.6 1st block: 2nd block (weight ratio) 10.5: 89.5 10.1: 89.9 11.2: 88.8 34.7: 65.3 10.1: 89.9 10.1: 89.9 4.2: 95.8 Monomer ratio unit: parts by weight
BA: butyl acrylate (homopolymer Tg: about -45 ℃)
HBA: 4-hydroxybutyl acrylate (homopolymer Tg: about -80 ℃)
MMA: methyl methacrylate (homopolymer Tg: about 110 ℃)
BMA: butyl methacrylate (homopolymer Tg: about 27 ℃)
HPMA: 2-hydroxypropyl methacrylate (homopolymer Tg: about 26 ℃)
Tg: Glass transition temperature
Mn: number average molecular weight
PDI: molecular weight distribution

Manufacturing example  8. Preparation of random copolymer (B4)

Nitrogen gas was refluxed, and 10 parts by weight of methyl methacrylate (MMA), 87.3 parts by weight of n-butyl acrylate, and 2.7 parts by weight of 4-hydroxybutyl acrylate were added to a 1L reactor equipped with a cooling device to facilitate temperature control. Then, n-dodecyl mercaptan was added in an amount of 200 ppm as a molecular weight modifier, and then 120 parts by weight of ethyl acetate was added as a solvent. Subsequently, nitrogen gas was purged for about 60 minutes for oxygen removal, and 0.05 parts by weight of a reaction initiator AIBN (azobisisobutyronitrile) was added while maintaining the temperature at 60 ° C. and reacted for about 8 hours to prepare a random copolymer. The number average molecular weight (Mn) of the prepared random copolymer (B5) was about 132000, and the molecular weight distribution (PDI) was about 4.6.

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 toluene diisocyanate-based crosslinking agent (Coronate L, manufactured by NPU, Japan), 0.1 parts by weight of DBTDL (Dibutyltin dilaurate) and beta-cyanoacetyl group Eggplant was mixed with 0.2 parts by weight of a silane coupling agent, and ethyl acetate was mixed as a solvent to adjust the coating solid content to about 33% by weight to prepare a coating solution (adhesive composition).

Preparation of adhesive polarizing plate

The prepared coating solution was coated on a release treatment surface of release PET (poly (ethylene terephthalate)) (MRF-38, manufactured by Mitsubishi) having a thickness of 38 µm, which was molded to release the thickness after drying to about 23 µm, and an oven at 110 ° C. For about 3 minutes. After drying, the WV (Wide View) liquid crystal layer coated on one side of the polarizing plate (TAC / PVA / TAC laminated structure: TAC = triacetyl cellulose, PVA = polyvinyl alcohol-based polarizing film) WV liquid crystal layer on the release PET on the The formed coating layer was laminated to prepare an adhesive polarizing plate.

Example  2 to 7 and Comparative example  1 to 12

In preparing the pressure-sensitive adhesive composition (coating solution), the pressure-sensitive adhesive composition (coating solution) and the 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 Tables 4 and 5 below.

Example One 2 3 4 5 6 7 8 acryl
polymer Kinds A1 A2 A3 A4 A1 A2 A3 A4 content 100 100 100 100 100 100 100 100 Coronate L 0.07 0.2 0.3 0.07 - - - - Coronate 2030 - - - - 0.07 0.2 0.3 0.07 DBTDL 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 SCA 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Content unit: parts by weight
TDI (Toluene Diisocyanate) crosslinker: Coronate L, Coronate 2030
DBTDL: Dibutyltin dilaurate
SCA: Silane coupling agent having beta-cyanoacetyl group (M812, manufactured by LG Chemical)

Comparative example One 2 3 4 5 6 7 8 9 10 11 12 13 14 acryl
polymer Kinds B1 B2 B3 B4 A1 A1 A1 A2 A3 A4 A1 A2 A3 A4 content 100 100 100 100 100 100 100 100 100 100 100 100 100 100 Coronate L 0.07 0.07 0.07 0.07 0.005 15 - - - - - - - - Takenate
D-110N - - - - - - 0.07 0.2 0.3 0.07 - - - - Coronate HK - - - - - - - - - - 0.07 0.2 0.3 0.07 DBTDL 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 SCA 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Content unit: parts by weight
TDI (Toluene Diisocyanate) crosslinker: Coronate L
XDI (Xylene Diisocyanate) crosslinking agent: Takenate D-110N
HDI (Hexamethylene Diisocyanate) Crosslinker: Coronate HK
DBTDL: Dibutyltin dilaurate
SCA: Silane coupling agent having beta-cyanoacetyl group (M812, manufactured by LG Chemical)

The evaluation results of the physical properties of Examples and Comparative Examples are shown in Tables 6 and 7 below.

Example One 2 3 4 5 6 7 8 Interfacial peel force (gf) 3450 3660 3800 3580 3510 3600 3720 3490 Heat resistant durability A A A A A A A A Moisture resistance and durability A A A A A A A A

Comparative example One 2 3 4 5 6 7 8 9 10 11 12 13 14 Interfacial peel force (gf) 1650 1780 1400 1310 1200 4120 1890 2270 2300 1500 1820 2190 2050 1570 Heat resistant durability C B C C C C A A B B A A A A Moisture resistance and durability C B C B C C A A A A A A A A

Claims (15)

It has a polarizing plate and an adhesive layer present on one or both sides of the polarizing plate,
The polarizing plate includes a protective film attached to both sides of the polarizer,
The pressure-sensitive adhesive layer is an adhesive polarizing plate formed on the opposite side of the polarizer of the protective film,
The adhesive layer is a block copolymer having a glass transition temperature of 50 ° C or higher, a first block having a number average molecular weight in the range of 10,000 to 150,000, a glass transition temperature of -10 ° C or lower, and a second block containing a hydroxyl group; And a pressure-sensitive adhesive composition comprising a toluene diisocyanate-based crosslinking agent.
delete The adhesive polarizing plate of claim 1, wherein the molecular weight distribution (Mw / Mn) of the block copolymer is in the range of 1.0 to 2.5.
The adhesive polarizing plate of claim 1, wherein the number average molecular weight of the block copolymer is in the range of 3,000 to 300,000.
The adhesive polarizing plate according to claim 1, wherein the first block comprises polymerized units derived from a (meth) acrylic acid ester monomer.
The adhesive polarizing plate according to claim 1, wherein the second block comprises 60 parts by weight to 99 parts by weight of a (meth) acrylic acid ester monomer and 1 part by weight to 40 parts by weight of a copolymerizable monomer having a hydroxyl group.
The adhesive polarizing plate of claim 1, wherein the block copolymer comprises 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.
The adhesive polarizing plate of claim 1, wherein the block copolymer is a diblock copolymer having a first block and a second block.
The adhesive polarizing plate according to claim 1, wherein the toluene diisocyanate-based crosslinking agent has two or more isocyanate groups.
The adhesive polarizing plate according to claim 1, wherein the toluene diisocyanate-based crosslinking agent comprises at least one selected from the group consisting of toluene diisocyanate, a multimer of toluene diisocyanate, and a reactant of a polyhydric alcohol compound and toluene diisocyanate.
The adhesive polarizing plate of claim 1, wherein the toluene diisocyanate-based crosslinking agent is contained in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the block copolymer.
delete delete delete A display device comprising the adhesive polarizing plate of claim 1.