KR20190017471A - Pressure-sensitive adhesive type optical member - Google Patents

Abstract

The present invention relates to an adhesive type optical member having excellent heat resistance, moisture resistance and durability, which comprises: a polarizing film; and an adhesive layer provided on at least one surface of the polarizing film, and including a crosslinkable block copolymer (A) and a non-crosslinkable random copolymer (B) including a monomer-derived unit having an aromatic structure.

Description

[0001] PRESSURE-SENSITIVE ADHESIVE TYPE OPTICAL MEMBER [0002]

The present application relates to a sticky optical member, and a display device including the same.

Background Art [0002] A liquid crystal display device (hereinafter, referred to as " LCD device ") includes a liquid crystal panel including a liquid crystal component injected between two transparent substrates, and a liquid crystal panel including, for example, a polarizing film, It is generally configured to include a functional film. In order to laminate the optically functional films or to attach the optically functional films to the liquid crystal panel, a pressure-sensitive adhesive is mainly used.

Since the liquid crystal display component parts listed above are made of different materials and thus have different physical properties, the dimensional stability between components under the high temperature and / or moist heat conditions may be deteriorated and warping may occur.

Also, thinning of the display can increase the warpage problem. On the other hand, a method of lowering the degree of crosslinking of the pressure-sensitive adhesive main component polymer may be considered in order to give the pressure-sensitive adhesive for optical film an anti-warp property, , The durability of the pressure-sensitive adhesive is lowered while increasing the change with time of the pressure-sensitive adhesive under the conditions of moisture resistance and / or moist heat resistance.

An object of the present invention is to provide a sticky optical member and a display device including the same.

Another object of the present invention is to provide a pressure-sensitive optical member having excellent durability reliability under severe conditions such as high temperature and high humidity, and capable of improving light leakage due to bending, and a display device including the same.

The above and other objects of the present application can be all attained by the present application which is described in detail below.

The present application relates to an optical member. More specifically, the present application relates to a sticky optical member provided with a pressure-sensitive adhesive layer on at least one surface of an optical member. As the optical member, an optically functional film such as a polarizing film, a retardation film, or a brightness enhancement film may be used. In one example, when a polarizing film is used as the optical member, the adhesive optical member may be referred to as an adhesive polarizing plate.

The polarizing film may be a functional film capable of extracting only light vibrating in one direction from incident light while vibrating in various directions. The kind of usable polarizing film is not particularly limited. For example, a general polarizing film known in this field can be used without limitation, such as a polyvinyl alcohol polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol film. The polyvinyl alcohol-based resin used for the polarizing film can be obtained by, for example, gelling a polyvinyl acetate-based resin. In this case, the polyvinyl acetate-based resin which 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 monomer copolymerizable with vinyl acetate include monomers such as unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group, or a mixture of two or more thereof. no. The degree of gelation of the polyvinyl alcohol-based resin may be generally from 85 mol% to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol resin may be further modified. For example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The degree of polymerization of the polyvinyl alcohol-based resin may be about 1,000 to 10,000, preferably about 1,500 to 5,000.

The polarizing film is formed by a process of stretching a polyvinyl alcohol resin film (uniaxially stretching), a process of dyeing a polyvinyl alcohol resin film with a dichroic dye and adsorbing the dichroic dye, a process of adsorbing a dichroic dye A process of treating a polyvinyl alcohol resin film with a boric acid aqueous solution and a process of washing with a boric acid aqueous solution after washing. As the dichroic dye, iodine or dichroic organic dyes may be used.

In one example, a protective film may be further provided on one side or both sides of the polarizing film, that is, the optical member. In this case, the pressure sensitive adhesive layer may be provided on one side of the protective film. The kind of protective film that can be used is not particularly limited and includes, for example, a cellulose-based film such as triacetylcellulose; Polyester-based films such as polycarbonate film or polyethylene terephthalate film; Polyethersulfone-based films; And / or a polyolefin film such as a polyethylene film, a polypropylene film, or a polyolefin film having a cyclo or norbornene structure or an ethylene propylene copolymer, may be used as a single layer or a multilayer film. The thickness of the protective film is not particularly limited.

The method of forming the pressure-sensitive adhesive layer on the optical member such as the polarizing film is not particularly limited. For example, a method of applying a pressure-sensitive adhesive composition for forming a pressure-sensitive adhesive layer described below using a bar coater or the like, and then curing or applying the pressure-sensitive adhesive composition to the surface of the releasable substrate and curing, and transferring the adhesive composition onto a polarizing film Can be used.

The pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer may comprise a crosslinkable block copolymer (A) and a non-crosslinkable random copolymer (B) containing a unit derived from a monomer having an aromatic structure. In the present application, the fact that a certain component is included in the adhesive composition can be interpreted the same as that the component is contained in the pressure sensitive adhesive layer. However, the crosslinkable block copolymer may be in a different state when it is included in the pressure-sensitive adhesive layer and when it is included in the pressure-sensitive adhesive composition. For example, the crosslinkable block copolymer (A) may not be cross-linked to each other in the composition but may be crosslinked with each other in the pressure-sensitive adhesive layer. The term " block copolymer " in this application may refer to a copolymer comprising blocks of different polymerized monomers. As used herein, the term aromatic structure means, unless otherwise specified, a structure in which one benzene ring structure or two or more benzene rings are linked together by sharing one or two carbon atoms, or connected by any linker May mean a monovalent or divalent moiety derived from a compound or derivative thereof. Since the non-crosslinkable random copolymer (B) contains an aromatic structure, the light compensation effect can be obtained even under a heat-resistant condition, and the light leakage can be effectively suppressed.

In one example, the weight average molecular weight (Mw) of the non-crosslinkable random copolymer (B) may range from 20,000 to 200,000. The non-crosslinkable random copolymer (B) may have a weight average molecular weight (Mw) of 20,000 or more, 30,000 or more, 40,000 or more, 50,000 or more, 60,000 or more, 70,000 or more, 80,000 or 90,000 or more, 200,000 or less, Or less than or equal to 170,000. The non-crosslinkable random copolymer having the above-mentioned molecular weight range can impart appropriate chain entanglement with the crosslinkable block copolymer (A) under normal temperature conditions, and can be obtained by crosslinking the non-crosslinkable copolymer when exposed to high temperature or high temperature and high humidity conditions. The flexibility is imparted by stretching and the aromatic groups contained in the non-crosslinkable copolymer are rearranged to suppress the light leakage phenomenon by the optical compensation effect. When the weight average molecular weight of the non-crosslinkable random copolymer (B) containing an aromatic group is less than 20,000, chain entanglement with the crosslinkable block copolymer (A) is insufficient and reliability of endurance against heat and moisture and heat is deteriorated, As shown in Fig. In addition, when the weight average molecular weight of the non-crosslinkable random copolymer (B) exceeds 200,000, sufficient flexibility can not be imparted to the pressure-sensitive adhesive, so that it becomes difficult to suppress the light spots.

The block copolymer (A) 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 the monomers contained in the block, and the method described in connection with the following experimental examples Can be measured.

In one example, the glass transition temperature of the first block may be at least 50 캜, at least 60 캜, at least 70 캜, or at least 80 캜. The upper limit of the glass transition temperature of the first block is not particularly limited, but may be, for example, 150 ° C or lower, 140 ° C or lower, 130 ° C or 120 ° C or lower.

In one example, the glass transition temperature of the second block may be below -10 占 폚, below -20 占 폚, below -30 占 폚, or below -40 占 폚. 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, -70 ° C or higher, or -60 ° C or higher.

The block copolymer (A) containing both of the two blocks satisfying the glass transition temperature range can form a fine phase separation structure in the pressure-sensitive adhesive, and exhibits appropriate cohesive force and stress relaxation property in accordance with temperature change , Adhesive properties that maintain excellent physical properties required for optical films such as interface adhesion, endurance reliability, light-shielding properties, and reworkability.

In one example, the weight average molecular weight (Mw) of the first block of the block copolymer (A) may range from 20,000 to 200,000. The weight average molecular weight of the first block may be, for example, the weight average molecular weight of the polymer produced by polymerizing only the monomer forming the first block. The weight molecular weight in the present application can be measured according to the method shown in the following examples using, for example, GPC (Gel Permeation Chromatograph). More specifically, the weight-average molecular weight Mw of the first block may be 20,000 or more, 25,000 or more, 30,000 or more, 35,000 or more, 40,000 or more, 45,000 or more, 50,000 or more, 55,000 or more, 60,000 or more, May be greater than or equal to 70,000, greater than or equal to 75,000, greater than or equal to 80,000, greater than or equal to 85,000, greater than or equal to 90,000, greater than or equal to 95,000 or greater than or equal to 100,000 and less than or equal to 200,000, less than or equal to 195,000, less than or equal to 190,000, less than or equal to 185,000, less than or equal to 180,000, As described above, when the molecular weight property of the first block of the block copolymer is controlled, a pressure-sensitive adhesive which maintains excellent physical properties required for optical films such as interface adhesion, endurance reliability, light-shielding property and reworkability can be formed .

In one example, the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the first block, i.e., the molecular weight distribution (PDI = Mw / Mn) may range from 1.0 to 3.0. More specifically, the lower limit value of the molecular weight distribution of the first block may be 1.05 or more, 1.10 or more, 1.15 or 1.20, and the lower limit may be 2.4 or less, 2.2 or less, 2.0 or less, 1.8 or less, or 1.6 or less.

As described above, when the molecular weight characteristics of the block copolymer are controlled, a pressure-sensitive adhesive which maintains excellent physical properties required in the adhesive optical member, such as interface adhesion, endurance reliability, light-shielding property, .

The block copolymer (A) comprising the monomer (a1) having a crosslinkable functional group may be an acrylic polymer.

In one example, the first block may comprise an alkyl (meth) acrylate monomer in polymerized form to ensure the glass transition temperature range. In the present application, the fact that a monomer is contained in a block or polymer in a polymerized form may mean that the monomer undergoes a polymerization reaction to form a skeleton of the block or polymer, for example, a main chain or a side chain.

In the formation of the first block, alkyl (meth) acrylate having an alkyl group having at least one carbon number may be used in consideration of cohesion, glass transition temperature and tackiness, etc., and may be an alkyl (meth) acrylate having 20 or less carbon atoms, 18 or less carbon atoms, , Alkyl (meth) acrylates having an alkyl group having 14 or less carbon atoms or 12 or less carbon atoms can be used. Examples of such monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, (Meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, pentyl (Meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, and lauryl (meth) acrylate.

In one example, in the first block formation, alkyl (meth) acrylates having the same carbon number may be used, or alkyl (meth) acrylates having alkyl groups having different carbon numbers from each other may be used. For example, the first block may be composed of an alkyl (meth) acrylate having an alkyl group having 1 to 3 carbon atoms or an alkyl (meth) acrylate having an alkyl group having 1 to 3 carbon atoms and an alkyl (Meth) acrylate in a polymerized form. Specifically, the first block comprises 60 to 100 parts by weight of an alkyl (meth) acrylate having an alkyl group having 1 to 3 carbon atoms and 0 to 40 parts by weight of an alkyl (meth) acrylate having an alkyl group having 4 to 10 carbon atoms, (Meth) acrylate having an alkyl group having 1 to 3 carbon atoms and an alkyl (meth) acrylate having an alkyl group having 4 to 10 carbon atoms in an amount of 15 to 35 Can be contained in a polymerized form. The term " part by weight " in the present application may mean a weight ratio between the components. (Meth) acrylate (a) having an alkyl group having 1 to 3 carbon atoms and alkyl (meth) acrylate having an alkyl group having 4 to 10 carbon atoms (b) (A) and the monomer (b) forming the polymerized unit of the first block is in the range of 65 to 85: 15 to 35 , And the first block is derived from 100 parts by weight of an alkyl (meth) acrylate (a) having an alkyl group having 1 to 3 carbon atoms and 0 part by weight of an alkyl (meth) acrylate having an alkyl group having 4 to 10 carbon atoms (Meth) acrylate having an alkyl group having 1 to 3 carbon atoms, the first block may be formed of only the alkyl (meth) acrylate having an alkyl group having 1 to 3 carbon atoms.

In one example, the first block may be a polymer of only alkyl (meth) acrylate monomers. Specifically, in order to form the first block, only alkyl (meth) acrylate monomers may be used. For example, the first block may be a single polymer of one alkyl (meth) acrylate monomer, or a copolymer of a monomer mixture containing only two or more alkyl (meth) acrylate monomers, Monomers may not be included. In the case of forming the first block by using a monomer such as styrene having an inter-carbon double bond in addition to the alkyl (meth) acrylate, the compatibility and the inter-block phase separation are lowered, so that it may be difficult to obtain sufficient durability and anti- .

The block copolymer (A) may be a crosslinkable block copolymer including a monomer having a crosslinkable functional group. More specifically, the block copolymer may include a copolymerizable monomer having a crosslinkable functional group in a polymerized form in the block.

Examples of the crosslinkable functional group include a hydroxyl group, a carboxyl group, an epoxy group, an isocyanate group or a nitrogen-containing functional group. The type of the copolymerizable monomer having a crosslinkable functional group is not particularly limited, and examples thereof include hydroxyl group-containing monomers such as hydroxy group alkyl (meth) acrylate or hydroxyalkylene glycol (meth) acrylate; (Meth) acryloyloxypropionic acid, 4- (meth) acryloyloxybutyric acid, acrylic acid dimer, itaconic acid, maleic acid, and Maleic anhydride and the like, or nitrogen-containing monomers such as (meth) acrylamide, N-vinylpyrrolidone or N-vinylcaprolactam, or the like, or a mixture of two or more thereof.

The crosslinkable functional group may be included in the second block having a relatively low glass transition temperature. In one example, the crosslinkable functional group is included only in the second block, and may not be included in the first block. When a crosslinkable functional group is included in the second block, a pressure-sensitive adhesive layer is formed which exhibits proper cohesive force and stress relaxation property in accordance with the temperature change and maintains good physical properties such as interface adhesion, endurance reliability, light- can do.

In one example, the second block may include a copolymerized monomer having an alkyl (meth) acrylate monomer and a crosslinkable functional group in a polymerized form. More specifically, the second block preferably comprises 80 to 99.9 parts by weight of an alkyl acrylate having 1 to 12 carbon atoms, 1 to 8 carbon atoms, or an alkyl group having 1 to 4 carbon atoms, and 0.1 to 20 parts by weight of a copolymerizable monomer having a crosslinkable functional group May be included in a polymerized form. In another example, the second block may comprise 85 to 99.9 parts by weight or 90 to 99.5 parts by weight of an alkyl acrylate having an alkyl group of 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, and 90 to 99.5 parts by weight of a copolymerizable 0.1 to 15 parts by weight of the monomer or 0.5 to 10 parts by weight of the monomer in polymerized form. As the alkyl (meth) acrylate monomer for forming the second block, monomers of the same kind as those usable for forming the first block may be used. When the second block satisfies the above composition, appropriate physical properties such as interface adhesion, endurance reliability, and appropriate cohesive force can be secured.

The copolymerizable monomer having a crosslinkable functional group contained in the second block has a site that can be copolymerized with another monomer contained in the block copolymer such as the alkyl acrylate monomer, It may be a monomer having a functional group. As the crosslinkable functional group contained in the copolymerizable monomer, the above-mentioned hydroxyl group, carboxyl group or nitrogen-containing functional group may be used.

In one example, the copolymerizable monomer having a crosslinkable functional group may be a monomer having a hydroxy group. More specifically, it is preferable to use 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) Hydroxyalkyl (meth) acrylates such as hydroxyoctyl (meth) acrylate; (Meth) acrylate, such as 2-hydroxyethyleneglycol (meth) acrylate or 2-hydroxypropyleneglycol (meth) acrylate, But are not limited thereto.

In one example, the block copolymer may be a diblock copolymer including the first and second blocks, i.e., a block copolymer containing only two blocks of the first block and the second block. have. By using the diblock copolymer, the adhesive property of the interface, the durability reliability, the stress relaxation property, the reworkability, and the like can be excellently maintained.

In one example, the block copolymer may comprise from 5 parts by weight to 50 parts by weight of the first block and from 50 parts by weight to 95 parts by weight of the second block. In another example, the block copolymer may comprise from 5 to 40 parts by weight or from 5 to 30 parts by weight of the first block and from 60 to 95 parts by weight or from 70 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 a pressure-sensitive adhesive composition and a pressure-sensitive adhesive having excellent physical properties.

In one example, the weight average molecular weight (Mw) of the block copolymer may be at least 400,000. The weight average molecular weight may be 400,000 or more, 420,000 or more, 440,000 or more, 460,000 or more, 480,000 or more, 500,000 or more, 520,000 or more, 540,000 or more, 560,000 or more, 580,000 or more or 600,000 or more, ≪ / RTI > The weight average molecular weight of the block copolymer can be controlled in an appropriate range to take account of the physical properties of the pressure-sensitive adhesive layer.

In one example, the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the block copolymer, i.e., the molecular weight distribution (PDI = Mw / Mn) . More specifically, the lower limit of the molecular weight distribution of the block copolymer may be, for example, at least 1.0, at least 1.1, at least 1.2, at least 1.3, at least 1.4, at least 1.5, or at least 1.6, 5.0 or less, 4.5 or less, 4.0 or less, or 3.5 or less.

As described above, when the molecular weight characteristics of the block copolymer are controlled, a pressure-sensitive adhesive having excellent properties required for optical films such as interfacial adhesion, endurance reliability, light-shielding properties and reworkability can be formed.

The method for producing the block copolymer is not particularly limited, and a known method can be used. For example, the block polymer can be polymerized by an LRP (Living Radical Polymerization) method. Specifically, anionic polymerization in which an organic rare earth metal complex is used as a polymerization initiator, or an organic alkali metal compound is used as a polymerization initiator in the presence of an inorganic acid salt such as a salt of an alkali metal or an alkaline earth metal, (ATRP) using an atom transfer radical polymerization agent as a polymerization initiator, and an atom transfer radical polymerization agent as a polymerization initiator, while generating electrons (ATRP), initiators for continuous activator regeneration (ATR), ATRP, and inorganic reductant reversible addition-cleavage (ATRP), which perform polymerization under an organic or inorganic reducing agent Reversible addition-cleavage chain transfer using chain transfer agent (RAFT), or a method of using an organic tellurium compound as an initiator. Among these methods, an appropriate method may be selected to produce the block copolymer.

The pressure-sensitive adhesive layer of the present application may further comprise, in addition to the crosslinkable block copolymer (A), a random copolymer, for example, a non-crosslinkable random copolymer (B) containing a monomer having an aromatic structure. The non-crosslinkable random copolymer (B) may be an acrylic copolymer.

In the present application, the term "non-crosslinkable random copolymer" means an acrylic polymer which does not contain, in the molecule, a functional group capable of reacting with the crosslinking agent described below, in contrast to the crosslinkable block copolymer (A). Since the non-crosslinkable random copolymer (B) does not participate in the crosslinking reaction with the crosslinking agent, it is possible to impart flexibility to the crosslinking network by the crosslinking block copolymer and the crosslinking agent, thereby improving the anti- , And it is possible to inhibit bleeding due to a proper cohesive force through hydrogen bonding with a hydroxyl group contained in the crosslinkable block copolymer (A) or an amine group generated after curing. In addition, the aromatic groups contained in the non-crosslinkable random copolymer can be effectively aligned under heat-resistant conditions, resulting in an optical compensation effect, thereby further suppressing light leakage.

In one example, the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn), that is, the molecular weight distribution (PDI = Mw / Mn) of the incompatible random copolymer (B) . The molecular weight distribution may be 1.1 or more, 1.2 or more, 1.3 or more, 1.4 or 1.5 or more, and the upper limit is not particularly limited, but may be about 8 or less, 7 or less, 6 or less or 5 or less, for example. By including the non-crosslinkable random copolymer satisfying the molecular weight distribution in the above range, the heat-resistant durability and the anti-wet heat resistance of the pressure-sensitive adhesive can be improved.

The glass transition temperature of the non-crosslinkable random copolymer (B) may be 0 占 폚 or lower. The lower limit of the glass transition temperature of the non-crosslinkable random copolymer is not particularly limited, and may be, for example, -80 ° C or higher, -70 ° C or higher, or -60 ° C or higher.

When the above-mentioned molecular weight range and the glass transition temperature range are satisfied, the type of the monomer used for forming the non-crosslinkable random copolymer is not particularly limited as long as it is a monomer having an aromatic structure. In one example, examples of the monomer having an aromatic structure include a (meth) acrylate monomer having an aromatic group. In addition, the non-crosslinkable random copolymer is a polymer having an aromatic group (a polymer of a methacrylate monomer .

Examples of the (meth) acrylate monomer having an aromatic group which the non-crosslinkable random copolymer (B) contains include benzyl (meth) acrylate, naphthyl (meth) acrylate, phenoxyethyl (meth) Butyl (meth) acrylate, 2- (1-naphthyloxy) ethyl (meth) acrylate, 2- Octyl (meth) acrylate, 8- (2-naphthyloxy) octyl (meth) acrylate, Acrylate, ethylene glycol o-phenyl phenyl ether (meth) acrylate, polyethylene glycol o-phenyl phenyl ether (meth) acrylate, and the like.

In one example, the pressure-sensitive adhesive layer of the present application may contain 5 to 50 parts by weight of a monomer unit having an aromatic structure with respect to 100 parts by weight of the incompatible random copolymer (B). The monomer unit having an aromatic structure may be used in an amount of 5 parts by weight or more, 8 parts by weight or more, 10 parts by weight or more, 12 parts by weight or more, 14 parts by weight or more, 16 parts by weight or less (based on 100 parts by weight of the non-crosslinkable random copolymer Not less than 18 parts by weight or not less than 20 parts by weight and not more than 50 parts by weight, not more than 45 parts by weight, not more than 40 parts by weight, not more than 38 parts by weight, not more than 36 parts by weight, not more than 34 parts by weight nor more than 32 parts by weight Or 30 parts by weight or less. When the content range is satisfied, excellent heat-resistant durability or anti-wet heat durability can be exhibited, and light leakage phenomenon can be effectively suppressed.

In one example, the random copolymer (B) may be contained in the adhesive composition or the pressure-sensitive adhesive layer in an amount of 1 to 20 parts by weight based on 100 parts by weight of the block copolymer (A). The random copolymer (B) may contain at least 1 part by weight, at least 2 parts by weight, at least 3 parts by weight, at least 4 parts by weight, or at least 5 parts by weight, relative to 100 parts by weight of the block copolymer (A) Or less, 19.5 parts or less, 19 parts or less, 18.5 parts or less, or 18 parts or less. When the above content range is satisfied, heat durability or anti-wet heat durability can be kept excellent, and excellent re-peeling property can be ensured.

The pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer may include at least one crosslinking agent (C) capable of reacting with the crosslinkable functional group of the block copolymer to form a chemical crosslinking structure. As the crosslinking agent, a multifunctional crosslinking agent having two or more functional groups capable of reacting with the crosslinkable functional group contained in the block copolymer may be used. Non-limiting examples of such crosslinking agents include isocyanate crosslinking agents, epoxy crosslinking agents, aziridine crosslinking agents and metal chelate crosslinking agents.

In one example, when the crosslinkable functional group is a hydroxy group, an isocyanate crosslinking agent may be used as the polyfunctional crosslinking agent. Examples of the isocyanate crosslinking agent include, but are not limited to, tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isoboron diisocyanate, tetramethylxylene diisocyanate and naphthalene diisocyanate. Diisocyanate compounds; Or a compound obtained by reacting the diisocyanate compound with a polyol. As the polyol, trimethylolpropane and the like may be used.

In one example, the multifunctional crosslinking agent (C) may be contained in the adhesive composition or the pressure sensitive adhesive layer in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the block copolymer (A). More specifically, the lower limit of the crosslinking agent content may be 0.01 parts by weight or more, 0.02 parts by weight or more, 0.03 parts by weight or more, 0.04 parts by weight or more, or 0.05 parts by weight or more and the upper limit may be 10 parts by weight or less, 6 parts by weight or less, 4 parts by weight or less, 3 parts by weight or less, 2 parts by weight or less, or 1 part by weight or less. In this range, the degree of crosslinking of the block copolymer can be appropriately controlled, and the gel fraction, cohesion, adhesion, durability and the like of the pressure-sensitive adhesive can be kept excellent.

The pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer may further include a silane coupling agent. For example, a silane coupling agent comprising an epoxy group, a thiol group, an amino group, a vinyl group, an epoxy group, a beta-cyanoacetyl group, an acetoacetyl group or halogen may be used. More specifically, the silane coupling agent may be a compound having a beta-cyano group represented by the following formula (1) or a compound having an acetoacetyl group represented by the following formula (2).

[Chemical Formula 1]

(R ₁ ) _n Si (R ₂ ) _(4-n)

(2)

(R ₃ ) _n Si (R ₂ ) _(4-n)

Wherein R ₁ is a beta-cyanoacetyl group or a beta-cyanoacetylalkyl group, R ₃ is an acetoacetyl group or an acetoacetylalkyl group, R ₂ is an alkoxy group, and n is an integer of 1 to 3 Number.

In the formula 1 or 2, the alkyl group may be an alkyl group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms or 1 to 4 carbon atoms, and the alkyl group may be linear, branched or cyclic . In the general 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 the alkoxy group may be linear, Can be.

Examples of the compound represented by Formula 1 or 2 include acetoacetylpropyltrimethoxysilane, acetoacetylpropyltriethoxysilane, betacyanoacetylpropyltrimethoxysilane, and betacyanoacetylpropyltriethoxysilane. But is not particularly limited thereto.

The silane coupling agent may be included in the range of 0.01 to 5 parts by weight based on 100 parts by weight of the block copolymer (A). Specifically, it may be contained in the composition in the range of 0.05 to 3 parts by weight based on 100 parts by weight of the block copolymer.

The pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer may further contain a tackifier, if necessary. Examples of the tackifier include a hydrocarbon resin or hydrogenated product thereof, a rosin resin or hydrogenated product thereof, a rosin ester resin or hydrogenated product thereof, a terpene resin or hydrogenated product thereof, a terpene phenol resin or hydrogenated product thereof, Polymerized rosin ester resin, and the like, or a mixture of two or more of them may be used, but the present invention 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.

The pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer may further include additives such as an epoxy resin, a curing agent, a UV stabilizer, an antioxidant, a colorant, a reinforcing agent, a filler, a defoamer, a surfactant or a plasticizer. The specific kind or content of the additive is not particularly limited.

In one example, the adhesive optical member of the present application can satisfy the condition of the following general formula (1). If the following conditions are not satisfied, the degree of bending of the adhesive type polarizing plate is large, so that the light leakage phenomenon of the polarizing plate or the display can be considered to be severe.

[Formula 1]

d <35 mm

In the general formula (1), d is a temperature at which the specimen having a 3.5 cm x 40.5 cm adhesive optical member attached to the glass is stored at a temperature of 55 to 65 ° C for 65 to 75 hours, And the opposite end represents the distance from the reference point. The d may be less than 35 mm, not more than 34 mm, not more than 33 mm, less than 32 mm, or less than 31 mm, and may be more than 0 mm, but is not limited thereto. At this time, the thickness of the pressure-sensitive adhesive layer may be 15 탆 to 25 탆.

In another example, the adhesive optical member of the present application is excellent in re-peeling property. More specifically, since the adhesive optical member has a certain range of adhesive force, it can be removed from the adherend without residue during re-peeling. For example, when the adhesive optical member is attached to a glass plate with a size of 25 mm × 100 mm, the peel strength measured at a peeling angle of 180 ° and a peeling speed of 300 mm / min is 2,000 gf / 25 mm or less. If the value exceeds 2,000 gf / 25 mm, the glass may be broken if the thickness of the glass is 0.7 t or less. Further, even if the glass is not broken, the residue is left on the adhesive agent when peeling off. The releasing force is obtained by attaching a releasing base material of PET to the end of a sticky optical member attached to the glass and then leaving the specimen at 70 to 90 캜 for 50 to 120 minutes under heating conditions, Can be measured after storage at room temperature and 55% to 65% relative humidity for 50 to 120 minutes. At this time, the thickness of the pressure-sensitive adhesive layer may be 15 탆 to 25 탆.

The present application also relates to a pressure sensitive adhesive composition. The pressure-sensitive adhesive composition of the present application may comprise a pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive composition comprising a crosslinkable block copolymer (A) and a non-crosslinkable random copolymer (B) containing a monomer- The non-crosslinkable random copolymer (B) may have a weight average molecular weight (Mw) of 20,000 to 200,000. The description of the crosslinkable block copolymer (A) contained in the pressure-sensitive adhesive composition of the present application and the non-crosslinkable random copolymer (B) comprising a monomer-derived monomer unit having an aromatic structure is the same as described above.

The present application is also directed to a display device. When the display device is an LCD, the device may include a liquid crystal panel and the adhesive optical member attached to one or both surfaces of the liquid crystal panel.

The liquid crystal panel may include, for example, a first substrate sequentially formed, a pixel electrode, a first alignment film, a liquid crystal layer, a second alignment film, 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 optical member may be attached to the glass substrate via a pressure-sensitive adhesive layer.

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

Examples of the liquid crystal panel in the apparatus include passive matrix type panels such as TN (twisted nematic) type, STN (super twisted nematic) type, F (ferroelectic) type or PD (polymer dispersed) type; An active matrix type panel such as a two terminal or a three terminal type; A known panel such as an in-plane switching (IPS) panel and a vertical alignment (VA) panel may be used.

Other configurations of the display device, for example, types 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 this field can be employed without limitation.

The present application can provide a pressure-sensitive adhesive composition for an optical film and an optical member capable of improving not only reliability in durability under severe conditions such as high temperature and high humidity but also light leakage phenomenon.

1 is a schematic view showing a method of measuring a fin distance according to the present application.

Hereinafter, the pressure-sensitive adhesive polarizer 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.

The physical properties of the present examples and comparative examples were evaluated in the following manner.

1. Evaluation of molecular weight

The weight average molecular weight (Mn) and the molecular weight distribution (PDI) of the block or block copolymer were measured using GPC (Gel Permeation Chromatograph), and the GPC measurement conditions were as follows. The calibration curve was prepared using standard polystyrene (Aglient system).

&Lt; GPC measurement condition >

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

Column: Two PL Mixed B connections

Column temperature: 40 ° C

Eluent: THF (Tetrahydrofuran)

Flow rate: 1.0 mL / min

Concentration: ~ 1 mg / mL (100 [mu] l injection)

2. Evaluation 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 A.

&Lt; Formula 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 is the glass transition temperature when each monomer forms a homopolymer. That is, in the formula (A), the value obtained by dividing the weight fraction of the used monomers by the glass transition temperature (Wn / Tn) obtained when the monomers are formed into the homopolymer is calculated for each monomer to be.

3. Durability evaluation

The pressure-sensitive 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 they were attached to a 19-inch commercial liquid crystal panel. Thereafter, the panel with the polarizing plate was stored for about 20 minutes in an autoclave (50 캜, 5 atm) to prepare a sample.

The durability against moisture and heat of the prepared sample was observed and evaluated for occurrence of bubbles and peeling at the adhesive interface in accordance with the following criteria after the sample was left for 500 hours at 60 ° C and 90% relative humidity.

In the case of heat resistance durability, the sample was allowed to stand at 80 DEG C for 500 hours, and the occurrence of bubbles and peeling was observed and evaluated according to the following criteria.

<Heat and Heat and Moisture Heat Durability Evaluation Criteria>

A: No bubbles and peeling occurred

B: Bubbles and / or slight peeling occurred

C: large amount of bubbles and / or peeling occurred

4. Evaluation of bending characteristics

Prepare STN sodalime glass (4 x 41 cm ² , 0.4 t) for bending. If there is no foreign substance on the glass, use it without washing. If there is foreign substance, clean it with EAc and IPA solvent, &Lt; / RTI &gt; The adhesive polarizing plate (coated product) prepared in Examples and Comparative Examples was prepared to have a length of 3.5 cm x 40.5 cm so that the MD direction was long and an adhesive type polarizing plate was attached to the glass for bending prepared using a laminator. Then, as shown in the figure below, a device capable of fixing the sample in the chamber was prepared, and one side of the glass with the adhesive type polarizing plate was fixed, and then the initial value, that is, the curved distance from the reference point, was measured. After the initial measurement, the sample was kept at 60 ° C for 72 hours, and the distance from the reference point was measured again. Three samples were prepared for the same prescription and the average of the separation distance was calculated.

5. Evaluation of re-peelability

The adhesive polarizing plates prepared in Examples and Comparative Examples were cut to have a width of about 25 mm and a length of about 100 mm to prepare samples. After attaching a polarizer to the sodalime glass for STN, attach PET (100 탆) to the end of the polarizer. After the sample was allowed to stand at 80 ° C for 60 minutes, it was sufficiently cooled under constant temperature and humidity conditions (25 ° C. and 60% relative humidity) and then subjected to peel test at a speed of 300 mm / min and 180 °. Respectively.

Manufacturing example

Production Example 1. Preparation of diblock copolymer (A1)

0.032 g of EBiB (ethyl 2-bromoisobutyrate), 11.4 g of methyl methacrylate (MMA) and 2.9 g of butyl methacrylate (BMA) were mixed in 6.1 g of ethyl acetate (EAc). The reactor containing the mixture was sealed, nitrogen purged and stirred at about 25 캜 for about 30 minutes, and dissolved oxygen was removed through bubbling. Then 0.002 g of CuBr ₂ , 0.006 g of tris (2-pyridylmethyl) amine, and 0.003 g of V-65 (2,2'-azobis (2,4-dimethyl valeronitrile) And the reaction was initiated by immersing in a reaction tank at about 67 ° C (polymerization of the first block). A mixture of 111.4 g of butyl acrylate (BA) previously bubbled with nitrogen, 1.1 g of hydroxybutyl acrylate (HBA) and 75 g of ethyl acetate (EAc) at the time when the conversion of methyl methacrylate was about 70% Was added in the presence of nitrogen. Thereafter, 0.004 g of CuBr ₂ , 0.01 g of TPMA and 0.05 g of azobisisobutyronitrile (AIBN) were added to the reactor, and chain extension reaction was carried out (polymerization of the second block). When the conversion of the monomer (BA) reaches 80% or more, the reaction mixture is exposed to oxygen, and the reaction is terminated by diluting with an appropriate solvent to obtain a P (MMA-BMA) -P (BA-HBA) diblock copolymer ). In the above procedure, AIBN was appropriately divided to the end of reaction in consideration of its half life.

Production Examples 2 to 4. Preparation of block copolymers (A2, A3 and A4)

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

Block copolymer A1 A2 A3 A4 The first block MMA ratio 80 70 80 80 BMA ratio 20 30 20 20 Tg (占 폚) 90 80 90 90 Mw (x10, 000) 15.1 16.3 15.8 13.4 PDI 1.34 1.36 1.38 1.43 The second block BA ratio 99 99 98.5 98.5 HBA ratio One One 1.5 1.5 Tg (占 폚) -45 -45 -45 -45 Block copolymer Block liver content 10:90 10:90 10:90 10:90 Mw (x10, 000) 60.2 63.5 66.7 63.8 PDI 1.8 2.3 2.1 2.6 Ratio of monomer or block (content): part by weight
BA: n-butyl acrylate (homopolymer Tg: about -45 ° C)
HBA: 4-hydroxybutyl acylate (homopolymer Tg: about -80 ° C)
MMA: methyl methacrylate (homopolymer Tg: about 110 ° C)
BMA: butyl methacrylate (homopolymer Tg: about 27 ° C)
Tg: glass transition temperature
Mw: weight average molecular weight
PDI: molecular weight distribution

Production Example 5. Preparation of random copolymer (B1)

150 parts by weight of toluene (Toluene) was added as a solvent to a 1 L reactor equipped with a cooling device so that nitrogen gas was refluxed and temperature was easily controlled. Nitrogen gas was purged for 60 minutes to remove oxygen, and the temperature was maintained at 80 캜. 0.5 part by weight of azobisisobutyronitrile (AIBN) as a reaction initiator and 0.5 part by weight of n-butylacrylate (BA) and phenoxyethyl acrylate (2-ethylhexyl acrylate) in which nitrogen gas was purged for 60 minutes. phemoxyethyl acrylate (2-PEA) were mixed in a weight ratio of 80:20, and the mixture was added to the reactor over a period of 4 hours, maintained at 80 ° C, and reacted for 1 hour after completion of charging to produce a random copolymer (C1) . The prepared copolymer had a weight average molecular weight of 127,000 and a molecular weight distribution of 2.2.

Production Examples 6 to 8. Preparation of random copolymers (B2, B3 and B4)

A random copolymer was prepared in the same manner as in Production Example 5 except that the kinds and ratios of raw materials used in the polymerization were adjusted as shown in Table 2 below.

Random copolymer B1 B2 B3 B4 Random copolymer BA ratio 80 70 70 100 2-PEA ratio 20 30 30 0 Tg (占 폚) -41 -39 -39 -45 Mw (x10, 000) 12.7 15.2 1.5 11.3 PDI 2.2 2.3 1.3 2.1 Ratio of monomer or block (content): part by weight
BA: n-butyl acrylate (homopolymer Tg: about -45 ° C)
2-PEA: 2-phenoxy ethyl acrylate (homopolymer Tg: about -22 ° C)
Tg: glass transition temperature
Mw: weight average molecular weight
PDI: molecular weight distribution

Production Example 9: Preparation of random copolymer (C1)

8 parts by weight of methyl methacrylate, 91 parts by weight of n-butylacrylate (BA), and 1 part by weight of hydroxybutyl acrylate were added to a 1 L reactor equipped with a cooling device so that nitrogen gas was refluxed and temperature was easily controlled A mixture of constituent monomers was added. Then, 150 parts by weight of ethylacetate (EAc) was added as a solvent. After nitrogen gas was purged for 60 minutes to remove oxygen, the temperature was maintained at 60 DEG C, and 0.03 part by weight of azobisisobutyronitrile (AIBN), which is a reaction initiator, was added. To prepare a copolymer (B3). The weight average molecular weight of the prepared copolymer was 1,200,000 and the molecular weight distribution was 5.1.

Example 1.

Preparation of Coating Liquid (Adhesive Composition)

10 parts by weight of the non-crosslinkable acrylic copolymer (C1), 0.08 part by weight of a crosslinking agent (Coronate L, manufactured by NPU of Japan), 0.1 part by weight of DBTDL (Dibutyltin dilaurate) And 0.2 part by weight of a silane coupling agent having a beta-cyanoacetyl group were mixed, and ethyl acetate was mixed as a solvent to adjust the coating solids to about 30% by weight to prepare a coating solution (pressure-sensitive adhesive composition).

Production of adhesive polarizer

The coating liquid thus prepared was coated on a release treated surface of poly (ethylene terephthalate) (MRF-38, manufactured by Mitsubishi) having a thickness of 38 탆 and subjected to release treatment so that the thickness after drying was about 23 탆, And maintained for 3 minutes. After drying, a coating layer formed on the releasing PET was laminated on one side of a polarizing plate (laminated structure of acryl / PVA / acryl: PVA = polyvinyl alcohol polarizing film) to prepare a pressure-sensitive polarizing plate.

Examples 2 to 4 and Comparative Examples 1 to 4

A pressure-sensitive adhesive composition (coating solution) and a pressure-sensitive polarizer were prepared in the same manner as in Example 1, except that components and ratios were adjusted as shown in Table 3 in the preparation of the pressure-sensitive adhesive composition (coating solution).

Example Comparative Example One 2 3 4 One 2 3 4 Block copolymer A Kinds A1 A2 A3 A4 A1 A1 A1 - content 100 100 100 100 100 100 100 - Random copolymer C Kinds - - - - - - - C1 content - - - - - - - 100 Random copolymer B Kinds B1 B1 B2 B2 - B3 B4 B1 content 10 15 10 15 - 10 10 10 Crosslinker content 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 DBTDL content 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 SCA content 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Content Unit: parts by weight
Cross-linking agent: Coronate L, Japan NPU
DBTDL: Dibutyltin dilaurate, manufactured by Sigma Aldrich
SCA: Cyanoacetoxypropyl trimethoxy silane, LG chem

The results of physical properties evaluation for each of the examples and comparative examples are shown in Table 4 below.

Example Comparative Example One 2 3 4 One 2 3 4 Fringe distance (mm) 21 17 24 22 36 19 26 40 Heat resistance durability A A A A B C A A Wet heat resistance A A A A B C B A Free residue (none: o, residue existence: X) ○ ○ ○ ○ ○ X X ○

Claims (20)

Polarizing film; And a pressure-sensitive adhesive layer provided on at least one surface of the polarizing film and formed of a pressure-sensitive adhesive composition comprising a crosslinkable block copolymer (A) and a non-crosslinkable random copolymer (B) containing a monomer-derived unit having an aromatic structure Including,
The non-crosslinkable random copolymer (B) has a weight average molecular weight (Mw) of 20,000 to 200,000.
The adhesive optical member according to claim 1, wherein the crosslinkable block copolymer (A) has 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.
The adhesive optical member according to claim 2, wherein the first block has a weight average molecular weight (Mw) of 20,000 to 200,000.
The adhesive optical member according to claim 2, wherein the first block is a polymer of an alkyl (meth) acrylate monomer.
The adhesive optical member according to claim 2, wherein the crosslinkable block copolymer (A) has a crosslinkable functional group in the second block.
The adhesive optical member according to claim 5, wherein the crosslinkable functional group is a hydroxyl group, a carboxyl group, an epoxy group, an isocyanate group or a nitrogen-containing functional group.
The adhesive optical member according to claim 2, wherein the second block comprises 80 to 99.9 parts by weight of an alkyl (meth) acrylate monomer and 0.1 to 20 parts by weight of a copolymerizable monomer having a crosslinkable functional group in a polymerized form.
The adhesive optical member according to claim 2, wherein the block copolymer (A) is a diblock copolymer composed of the first block and the second block.
The adhesive optical member according to claim 2, wherein the block copolymer (A) comprises 5 to 50 parts by weight of the first block and 50 to 95 parts by weight of the second block.
The adhesive optical member according to claim 1, wherein the crosslinkable block copolymer (A) has a weight average molecular weight (Mw) of 400,000 or more.
The adhesive optical member according to claim 1, wherein the non-crosslinkable random copolymer (B) has a molecular weight distribution (PDI, Mw / Mn) of 1.1 or more.
The adhesive optical member according to claim 1, wherein the non-crosslinkable random copolymer (B) has a glass transition temperature of 0 ° C or lower.
The adhesive optical member according to claim 1, wherein the non-crosslinkable random copolymer (B) is a polymer of a (meth) acrylate monomer.
The adhesive optical member according to claim 1, wherein 5 to 50 parts by weight of a monomer unit having an aromatic structure is added to 100 parts by weight of the non-crosslinkable random copolymer (B).
The adhesive optical member according to claim 1, comprising 1 to 20 parts by weight of a non-crosslinkable random copolymer (B) relative to 100 parts by weight of the crosslinkable block copolymer (A).
The adhesive optical member according to claim 1, wherein the multifunctional crosslinking agent (C) is contained in an amount of 0.01 to 10 parts by weight relative to 100 parts by weight of the block copolymer (A).
The adhesive optical member according to claim 1, further comprising a silane coupling agent.
The adhesive optical member according to claim 1, which satisfies the condition of the following general formula (1)
[Formula 1]
d <35 mm
In the general formula (1), d is a temperature at which the specimen having a 3.5 cm x 40.5 cm adhesive optical member attached to the glass is stored at a temperature of 55 to 65 ° C for 65 to 75 hours, And the opposite end represents the distance from the reference point.
(B) comprising a cross-linkable block copolymer (A) and a unit derived from a monomer having an aromatic structure,
The non-crosslinkable random copolymer (B) has a weight average molecular weight (Mw) of 20,000 to 200,000.
A display device comprising a liquid crystal panel having the adhesive optical member according to claim 1 attached to one or both surfaces thereof.

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