KR102365623B1 - Adhesive composition for polarizing plate, polarizing plate and display device - Google Patents

Abstract

The present invention is an acrylic eye formed by polymerizing a mixture of an alkali metal salt with a monomer mixture comprising an alkyl (meth)acrylate-based monomer, a (meth)acrylic monomer containing a hydroxyl group, and a (meth)acrylic monomer containing a carboxy group It relates to a pressure-sensitive adhesive composition for a polarizing plate, including a monomer, wherein the alkali metal salt is mixed in an amount of 10 to 30 parts by weight based on 100 parts by weight of the monomer mixture, and a polarizing plate and display device manufactured using the same.

Description

Adhesive composition for a polarizing plate, a polarizing plate, and a display device TECHNICAL FIELD

The present invention relates to a pressure-sensitive adhesive composition for a polarizing plate, a polarizing plate, and a display device, and more particularly, a pressure-sensitive adhesive composition, including an acrylic ionomer, which exhibits different modulus properties depending on temperature to improve panel warpage And it relates to a polarizing plate and a display device manufactured using the same.

A polarizing plate is an optical element for converting natural light or arbitrary polarized light into polarized light vibrating in a specific direction, and is applied to display devices such as a liquid crystal display (LCD) and an organic light emitting device (Organic Light Emitting Device). Display devices including a polarizing plate are used in various products such as portable, vehicle-mounted, outdoor meter, computer, TV, and the like, and the field of application thereof is gradually expanding. As the field of application is diversified, the environment in which the display device is used is also becoming harsh, and accordingly, it is required to have high durability even in an environment in which high temperature, high humidity, and/or temperature or humidity change is extreme.

However, in the case of the conventional display devices, defects such as light leakage or panel warpage are often caused under harsh conditions of use. For example, in a high-temperature and high-humidity environment, panel warpage occurs due to a difference in shrinkage between the upper polarizing plate and the lower polarizing plate, in particular, a difference in shrinkage in the direction of the stretching axis of the polarizing plate. In the case of a device in which the optical axes of the upper polarizer and the lower polarizer cross at 0 degrees and 90 degrees, such as a liquid crystal display in IPS mode or VA mode, the elongation axes of the upper polarizer and the lower polarizer are asymmetrically disposed. Due to this, when the shrinkage occurs, the curl of the upper polarizing plate and the lower polarizing plate is different, and the liquid crystal panel is bent in a direction in which the curl of the upper polarizing plate and the lower polarizing plate is large. When the panel warpage occurs as described above, the panel is pressed by the case when the panel is fixed, thereby causing light leakage due to the occurrence of liquid crystal non-uniformity.

In order to solve the panel warpage problem as described above, conventionally, a method of forming an adhesive layer having different adhesive strength on an upper polarizing plate and a lower polarizing plate, a method of lowering the crosslinking density of the adhesive, and a block air having a hard segment and a soft segment as an adhesive A method using coalescence has been proposed.

However, in the case of a method of differentiating the adhesive strength of the upper polarizing plate and the lower polarizing plate, the effect of improving panel warpage in a device in which the optical axes of the upper and lower polarizing plates are arranged at 0 degrees and 90 degrees is insignificant, and two kinds of adhesives have to be used. Therefore, there is a problem in that productivity is reduced. In addition, in the case of a method of lowering the crosslinking density of the pressure-sensitive adhesive, there is a problem in that durability is reduced as the crosslinking density decreases. There is a problem in that the storage stability and thermal stability of the copolymer polymerized in

Therefore, without reducing the durability of the polarizing plate, the development of a new pressure-sensitive adhesive composition capable of improving the panel warpage is required.

An object of the present invention is to solve the above problems, and to provide a pressure-sensitive adhesive composition for a polarizing plate that exhibits different modulus characteristics depending on temperature and has excellent durability and panel warpage suppression effect.

In addition, the present invention is to provide a polarizing plate including a pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition as described above and a display device including the same.

In one aspect, the present invention is formed by polymerizing a mixture of an alkali metal salt with a monomer mixture comprising an alkyl (meth)acrylate-based monomer, a (meth)acrylic monomer containing a hydroxyl group, and a (meth)acrylic monomer containing a carboxyl group It provides a pressure-sensitive adhesive composition for a polarizing plate, including an acrylic inomer, wherein the alkali metal salt is mixed in an amount of 10 to 30 parts by weight based on 100 parts by weight of the monomer mixture.

In another aspect, the present invention provides a polarizing film; and an adhesive layer formed on one or both sides of the polarizing film and comprising a cured product of the pressure-sensitive adhesive composition for a polarizing plate according to the present invention.

In another aspect, the present invention provides a display device including the polarizing plate of the present invention.

The pressure-sensitive adhesive composition according to the present invention includes an acrylic ionomer in which a coordination bond is formed between the acrylic copolymer and a metal ion by polymerization of an alkali salt during polymerization of the acrylic copolymer. The acrylic ionomer has a hard characteristic by maintaining the coordination bond between the acrylic copolymer and the metal ion at room temperature, but at a high temperature of 80° C. or more, the coordination bond is dissociated and a soft characteristic appears. Therefore, the pressure-sensitive adhesive composition according to the present invention is excellent in stress relaxation properties in high temperature and high temperature/high humidity environment, thereby effectively improving panel warpage. In addition, the pressure-sensitive adhesive composition according to the present invention has excellent durability.

Hereinafter, the present invention will be described in detail.

When 'including', 'having', 'consisting', etc. mentioned in this specification are used, other parts may be added unless 'only' is used. When a component is expressed in the singular, cases including the plural are included unless otherwise explicitly stated.

In interpreting the components, it is construed as including an error range even if there is no separate explicit description.

In this specification, "(meth)acryl" is a generic term for acryl and methacryl. For example, (meth)acrylate includes methacrylate and acrylate, and (meth)acrylic acid includes acrylic acid and methacrylic acid.

In this specification, "X to Y" which shows a range means "X or more and Y or less".

Hereinafter, the pressure-sensitive adhesive composition according to the present invention will be described in detail.

adhesive composition

(1) Acrylic ionomer

The pressure-sensitive adhesive composition according to the present invention, An acrylic ionomer formed by polymerizing a mixture of an alkyl (meth)acrylate-based monomer, a (meth)acrylic monomer containing a hydroxyl group, and a (meth)acrylic monomer containing a carboxy group, and an alkali metal salt do.

The acrylic ionomer refers to a polymer in which a metal atom is partially substituted in the carboxy group of the acrylic copolymer, wherein the carboxy group and the metal atom are bonded through a coordination bond. Such an acrylic ionomer has a hard characteristic because the coordination bond between the acrylic copolymer and the metal ion is maintained at room temperature. ) has a characteristic. Accordingly, the pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition containing the acrylic ionomer as described above has a high modulus at room temperature and exhibits excellent durability, and has a relatively low modulus in a high temperature or high temperature/high humidity environment, an upper polarizing plate and a lower polarizing plate It is possible to minimize the occurrence of panel warpage by alleviating the stress caused by the difference in the shrinkage of the panel.

The acrylic ionomer of the present invention may be prepared by mixing an alkali metal salt with a monomer mixture and then polymerization.

Examples of the alkali metal salt include a metal cation selected from Li ⁺ and Na ⁺ and Cl ^- , Br ^- , I ^- , BF ₄ ^- . PF ₆ ^- , AsF ^- , ClO ₄ ^- , NO ₂ ^- , CO ₃ ^- , N(CF ₃ SO ₂ ) ₂ ^- , N(CF ₃ CO) ₂ ^- , N(C ₂ F ₅ CO) ₂ ^- , N (C ₂ F ₅ SO ₂ ) ₂ ^- , N(C ₄ F ₉ SO ₂ ) ₂ ^- , C(CF ₃ SO ₂ ) ₃ ^- , and CF ₃ SO ₃ ^- a compound consisting of an anion selected from the group consisting of and, preferably, NaClO ₄ , LiN(CF ₃ SO ₂ ) ₂ , LiClO ₄ , LiPF ₆ , or a mixture thereof may be used.

In this case, the alkali metal salt may be included in an amount of 10 to 30 parts by weight, preferably 15 to 25 parts by weight, based on 100 parts by weight of the monomer mixture. When the content of the alkali metal salt is less than 10 parts by weight, the ionomer is not sufficiently formed, so that the stress relaxation effect is insignificant.

Meanwhile, the monomer mixture includes an alkyl (meth)acrylate-based monomer, a (meth)acrylic monomer including a hydroxyl group, and a (meth)acrylic monomer including a carboxy group.

The alkyl (meth) acrylate-based monomer is for imparting adhesive strength, and preferably includes an alkyl group having 1 to 14 carbon atoms. When the alkyl group included in the alkyl (meth) acrylate-based monomer becomes too long, the cohesive force of the pressure-sensitive adhesive is lowered, and it may be difficult to control the glass transition temperature (Tg) or the adhesiveness. For example, examples of the alkyl (meth) acrylate-based monomer include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n- Butyl (meth)acrylate, t-butyl (meth)acrylate, sec-butyl (meth)acrylate, pentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-ethylbutyl (meth)acrylic rate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, lauryl (meth) acrylate and tetradecyl (meth) acrylate, and in the present invention, One or a mixture of two or more of the above may be used.

The alkyl (meth)acrylate-based monomer may be included in an amount of 87 to 94.5 parts by weight, preferably 87 to 92 parts by weight, based on 100 parts by weight of the monomer mixture. When the content of the alkyl (meth) acrylate-based monomer satisfies the above range, excellent adhesion and durability can be obtained.

Next, the (meth)acrylic monomer including the hydroxyl group is for improving the adhesive strength of the pressure-sensitive adhesive composition and forming a crosslinked structure with the crosslinking agent, for example, 2-hydroxyethyl (meth)acrylate, 2- Hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 2-hydroxyethylene glycol (meth) ) acrylate, 2-hydroxypropylene glycol (meth) acrylate or a mixture thereof may be used, but is not limited thereto.

The (meth)acrylic monomer including the hydroxyl group may be included in an amount of 0.5 to 3 parts by weight, preferably 1 to 3 parts by weight, based on 100 parts by weight of the monomer mixture. When the content of the (meth)acrylic monomer containing a hydroxyl group satisfies the above range, cohesive properties can be secured, and when it is less than 0.5 parts by weight, the adhesive is destroyed upon re-peelling, and when it exceeds 3 parts by weight, sufficient Adhesion cannot be ensured.

Next, the (meth)acrylic monomer containing the carboxyl group is for forming a coordination bond with the alkali metal salt, for example, (meth)acrylic acid, 2-(meth)acryloyloxyacetic acid, 3-(meth) Acryloyloxy propyl acid, 4-(meth)acryloyloxy butyric acid, acrylic acid duplex, itaconic acid, maleic acid, maleic anhydride, or mixtures thereof may be used, but not limited thereto.

The (meth)acrylic monomer including the carboxyl group may be included in an amount of 5 to 10 parts by weight, preferably 6 to 9 parts by weight, based on 100 parts by weight of the monomer mixture. When the content of the (meth)acrylic monomer including a carboxyl group is less than 5 parts by weight, the ionomer structure cannot be formed, and when it exceeds 10 parts by weight, the adhesive strength increases and the re-peelability is deteriorated.

According to one embodiment, the monomer mixture is, based on 100 parts by weight of the monomer mixture, 87 to 94.5 parts by weight of an alkyl (meth)acrylate-based monomer, 0.5 to 3 parts by weight of a (meth)acrylic monomer including a hydroxyl group, and 5 It may contain a (meth)acrylic monomer containing a carboxyl group to 10 parts by weight.

On the other hand, the method of polymerizing the mixture of the monomer mixture and the alkali metal salt is not particularly limited, and various polymerization methods known in the art, for example, solution polymerization, photopolymerization, bulk polymerization, suspension polymerization or emulsion polymerization, etc. Polymerization methods may be used. A polymerization initiator, molecular weight control, etc. may be additionally added during the polymerization, and the input timing of each component is not particularly limited. That is, the components may be added in batches, or may be divided and added several times.

In the present invention, in particular, the acrylic ionomer can be prepared using a solution polymerization method, and the solution polymerization is performed at 50°C to 140°C by adding an initiator, a molecular weight regulator, etc. in a state where each monomer is uniformly mixed. It is preferable to carry out with temperature. Examples of the initiator that can be used in this process include azo initiators such as azobisisobutyronitrile or azobiscyclohexane carbonitrile; and/or a conventional initiator such as a peroxide such as benzoyl peroxide or acetyl peroxide, and one or a mixture of two or more thereof may be used, but is not limited thereto. In addition, as the molecular weight modifier, mercaptans such as t-dodecyl mercaptan or n-dodecyl mercaptan, defentin, or terpenes of t-terpene, chloroform, or a halogenated hydrocarbon of carbon tetrachloride, or pentaerythritol tetra Kiss 3-mercapto propionate may be used, but is not limited thereto.

Meanwhile, the acrylic ionomer of the present invention prepared by the above method may have a weight average molecular weight of 1,000,000 to 2,500,000, preferably 1,200,000 to 2,000,000. When the weight average molecular weight of the acrylic ionomer satisfies the above range, excellent durability can be realized.

(2) multifunctionality crosslinking agent

Meanwhile, the pressure-sensitive adhesive composition according to the present invention may further include an isocyanate-based polyfunctional crosslinking agent together with the acrylic ionomer.

The polyfunctional crosslinking agent reacts with the hydroxyl group in the acrylic ionomer to form a crosslinked structure, thereby improving the durability of the adhesive layer, for example, toluene diisocyanate, 2,4-trylene diisocyanate, 2,6- torylene diisocyanate, hydrogenated torylene diisocyanate, isoform diisocyanate, 1,3-xylene diisocyanate, 1,4-xylene diisocyanate, diphenylmethane-4,4-diisocyanate, 1,3-bisisocyanato Methyl cyclohexane, tetramethylxylene diisocyanate, 1,5-naphthalene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethyl hexamethylene diisocyanate, 2,4,4-trimethyl hexamethylene diisocyanate, trimethylolpropane Modified toluene diisocyanate, trimethylolpropane modified tolylene diisocyanate, trimethylolpropane torylene diisocyanate adduct, trimethylolpropane xylene diisocyanate adduct, toriphenylmethane isocyanate, methylene bistriisocyanate, polyols thereof (trimethylolpropane) or a mixture thereof may be used.

The isocyanate-based polyfunctional crosslinking agent may be included in an amount of 0.01 to 5 parts by weight, preferably 0.5 to 4 parts by weight, more preferably 0.5 to 3 parts by weight based on 100 parts by weight of the acrylic ionomer. When the content of the isocyanate-based polyfunctional crosslinking agent is less than 0.01 parts by weight, it is difficult to expect a crosslinking effect, and when it exceeds 5 parts by weight, sufficient adhesion cannot be secured due to an increase in cohesive force.

(3) other ingredients

The pressure-sensitive adhesive composition of the present invention may further include other components such as a solvent, a silane coupling agent, a crosslinking catalyst, a tackifying resin, and an additive, in addition to the components described above for controlling physical properties.

The pressure-sensitive adhesive composition of the present invention may further include a solvent for viscosity control. In this case, the solvent may include, for example, ethyl acetate, n-pentane, isopentane, neopentane, n-hexane, n-octane, n-heptane, methyl ethyl ketone, acetone, toluene, or a combination thereof, The present invention is not limited thereto.

In addition, the pressure-sensitive adhesive composition of the present invention may further include a silane coupling agent.

Such a coupling agent is intended to improve the adhesion between the pressure-sensitive adhesive and the polarizing plate or the adherend. Examples of the coupling agent that can be used in the present invention include γ-glycidoxypropyl triethoxy silane, γ-glycidoxypropyl trimethoxy silane, γ-glycidoxypropyl methyldiethoxy silane, γ-glycidoxy propyl triethoxy silane, 3-mercaptopropyl trimethoxy silane, vinyltrimethoxysilane, vinyltriethoxy silane, γ-methacryloxypropyl trimethoxy silane, γ-methacryloxypropyl triethoxy silane, γ-aminopropyl trimethoxy silane, γ-aminopropyl triethoxy silane, 3-isocyanatopropyl triethoxy silane, γ-acetoacetylpropyl trimethoxysilane, γ-acetoacetylpropyl triethoxy silane, and β-cyanoacetyl trimethoxy silane, β-cyanoacetyl triethoxy silane, and acetoxyaceto trimethoxy silane, and one or a mixture of two or more of the above may be used. In the present invention, it is preferable to use a silane-based coupling agent having an acetoacetate group or a β-cyanoacetyl group, but is not limited thereto.

In the composition of the present invention, the silane-based coupling agent may be included in an amount of 0.01 parts by weight to 5 parts by weight, preferably 0.01 parts by weight to 1 part by weight, based on 100 parts by weight of the acrylic copolymer. When the content of the coupling agent is less than 0.01 parts by weight, the effect of increasing the adhesion is insignificant, and when it exceeds 5 parts by weight, there is a fear that durability may be lowered.

The pressure-sensitive adhesive composition of the present invention may further include a crosslinking catalyst. The crosslinking catalyst is for accelerating curing (crosslinking) of the pressure-sensitive adhesive layer, and when a crosslinking catalyst is included in the pressure-sensitive adhesive composition, there is an advantage that a separate aging (aging) process is not required after forming the pressure-sensitive adhesive layer. Examples of the crosslinking catalyst include bis(tri-n-butyltin)oxide, bis(tri-n-butyltin)sulfate, di-n-butyldiphenyltin, and di-n-butyltinbis(acetyl). acetonate), di-n-butyltin bis(2-ethylhexanoate), di-n-butyltin dichloride, di-n-butyltin dilaurate, di-n-butyltin oxide, dimethyldiphenyltin, Dimethyltin dichloride, diphenyltin dichloride, diphenyltin oxide, hexa-n-butyltin, hexaphenyltin, tetra-n-butyltin, tetraphenyltin, tin (II) acetate, tin (II) acetylacetonate, Tin (II) chloride, tin (II) iodide, tin (II) oxalate, etc. may be used, but is not limited thereto.

Meanwhile, the crosslinking catalyst may be included in an amount of 0.001 parts by weight to 0.5 parts by weight, preferably 0.001 parts by weight to 0.1 parts by weight, based on 100 parts by weight of the acrylic copolymer. If the content of the crosslinking catalyst is less than 0.001 parts by weight, the curing accelerating effect is insignificant, and when it exceeds 0.5 parts by weight, there is a fear that durability may be lowered.

The pressure-sensitive adhesive composition of the present invention may further include 1 part by weight to 100 parts by weight of a tackifying resin based on 100 parts by weight of the acrylic copolymer from the viewpoint of adjusting the adhesive performance. The kind of such tackifying resin is not particularly limited, and for example, (hydrogenated) hydrocarbon-based resin, (hydrogenated) rosin resin, (hydrogenated) rosin ester resin, (hydrogenated) terpene resin, (hydrogenated) terpene phenol resin, One kind or a mixture of two or more kinds of polymerized rosin resin or polymerized rosin ester resin may be used. When the content of the tackifying resin is less than 1 part by weight, there is a fear that the effect of addition is insignificant, and when it exceeds 100 parts by weight, there is a fear that compatibility and/or the effect of improving cohesion may be reduced.

The pressure-sensitive adhesive composition of the present invention also includes one or more additives selected from the group consisting of an epoxy resin, a crosslinking agent, a UV stabilizer, an antioxidant, a colorant, a reinforcing agent, a filler, an antifoaming agent, a surfactant, and a plasticizer to the extent that the effect of the invention is not affected. may further include.

Polarizer

Next, a polarizing plate according to the present invention will be described.

The present invention also provides a polarizing film; and a pressure-sensitive adhesive layer formed on one or both sides of the polarizing film and containing a cured product of the pressure-sensitive adhesive composition according to the present invention.

The type of the polarizing film used in the present invention is not particularly limited, and a general type known in this field may be employed. For example, the polarizing film may include a polarizer; and a protective film formed on one or both surfaces of the polarizer.

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

A polarizer is a functional film or sheet that can extract only light vibrating in one direction from incident light while vibrating in multiple directions. Such a polarizer may be, for example, a form in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film. Polyvinyl alcohol-type resin which comprises a polarizer can be obtained by gelatinizing polyvinyl acetate-type resin, for example. In this case, the polyvinyl acetate-based resin that can be used may include not only a homopolymer of vinyl acetate, but also a copolymer of vinyl acetate and other monomers copolymerizable therewith. In the above, examples of the monomer copolymerizable with vinyl acetate include one or a mixture of two or more of unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group. not. The gelation degree of the polyvinyl alcohol-based resin may be usually about 85 mol% 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 usually about 1,000 to 10,000, preferably about 1,500 to 5,000.

Polyvinyl alcohol-type resin as described above can be formed into a film, and it can be used as a raw film of a polarizer. A method of forming the polyvinyl alcohol-based resin into a film is not particularly limited, and a general method known in this field may be used.

The thickness of the raw film formed of the polyvinyl alcohol-based resin is not particularly limited, and for example, may be appropriately controlled within the range of 1 μm to 150 μm. In consideration of ease of stretching, etc., the thickness of the raw film may be controlled to 10 μm or more.

The polarizer is a step of stretching (ex. uniaxial stretching) the polyvinyl alcohol-based resin film as described above, dyeing the polyvinyl alcohol-based resin film with a dichroic dye, adsorbing the dichroic dye, and adsorbing the dichroic dye It can be manufactured through a process of treating the polyvinyl alcohol-based resin film with an aqueous solution of boric acid and a process of washing with water after treatment with an aqueous solution of boric acid. In the above, as the dichroic dye, iodine or a dichroic organic dye may be used.

The polarizing film of the present invention may further include a protective film formed on one or both surfaces of the polarizer. The kind of protective film that can be included in the polarizing plate of the present invention is not particularly limited, and for example, a cellulose-based film such as triacetyl cellulose; polyester-based films such as polycarbonate films or polyethylene terephthalate films; polyethersulfone-based film; and/or a polyethylene film, a polypropylene film, or a polyolefin film having a cyclo- or norbornene structure, or a polyolefin-based film such as an ethylene propylene copolymer may be formed as a multilayer film in which a protective film is laminated. At this time, the thickness of the protective film is also not particularly limited, and may be formed to a normal thickness.

In the present invention, the method of forming the pressure-sensitive adhesive layer on the polarizing film is not particularly limited, and for example, a method of applying and curing the pressure-sensitive adhesive composition (coating solution) to the film or device by a conventional means such as a bar coater, and curing, or the pressure-sensitive adhesive After the composition is once applied to the surface of the releasable substrate and cured, a method of transferring the formed pressure-sensitive adhesive layer to the surface of a polarizing film or device may be used.

In the present invention, the process of forming the pressure-sensitive adhesive layer is also preferably performed after sufficiently removing the bubble-inducing components such as volatile components or reaction residues inside the pressure-sensitive adhesive composition (coating solution). Accordingly, the crosslinking density or molecular weight of the pressure-sensitive adhesive is too low, and the elastic modulus is lowered, and bubbles present between the glass plate and the pressure-sensitive adhesive layer become large at a high temperature, thereby preventing problems such as forming a scattering body inside.

In addition, the method of curing the pressure-sensitive adhesive composition of the present invention during the manufacture of the polarizing plate is also not particularly limited, and for example, the pressure-sensitive adhesive layer is heated at an appropriate temperature so that a crosslinking reaction between the acrylic copolymer and the crosslinking agent contained in the composition can be induced. It can be carried out in such a way that it is maintained in

The polarizing plate of the present invention may further include one or more functional layers 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 luminance enhancing film.

display device

Next, the display device of the present invention will be described.

The display device of the present invention includes the above-described polarizing plate according to the present invention.

More specifically, the display device may be a liquid crystal display device including a liquid crystal panel in which the polarizing plate according to the present invention is bonded to one or both surfaces. In this case, the type of the liquid crystal panel is not particularly limited. In the present invention, for example, without being limited to the type, F various passive matrices including TN (Twisted Neumatic) type, STN (Super Twisted Neumatic) type, F (ferroelectric) type, PD (polymer dispersed LCD) type, etc. method; Various active matrix methods, including two-terminal and three-terminal; Any known liquid crystal panel including a horizontal electric field type (IPS mode) panel and a vertical alignment type (VA mode) panel may be applied. In addition, the type of other components included in the liquid crystal display of the present invention and a manufacturing method thereof are not particularly limited, and general configurations in this field may be employed without limitation.

Example

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily carry out the present invention. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein.

production example 1: Acrylic ionomer (A)

87 parts by weight of butyl acrylate (BA), 5 parts by weight of methyl methacrylate (MMA), 1 weight of hydroxybutyl acrylate (HBA) in a 3L reactor in which nitrogen gas is refluxed and a cooling device is installed for easy temperature control 15 parts by weight of NaClO ₄ as an alkali metal salt was added to a monomer mixture containing 7 parts by weight of acrylic acid (AA) and 100 parts by weight of ethyl acetate (EAc) as a solvent. Then, nitrogen gas was purged for 60 minutes to remove oxygen, and then the temperature was maintained at 63°C. Then, 0.015 parts by weight of n-dodecylmercaptan (n-DDM) as a molecular weight regulator and 0.05 parts by weight of azobis(2-4-dimethylvaleronitrile (V-65, manufacturer: Wako) as a polymerization initiator are additionally added While reacting for 8 hours, an acrylic ionomer (A) was prepared.

production example 2: Acrylic ionomer (B)

In the same manner as in Preparation Example 1, the acrylic ionomer (B) was prepared in the same manner as in Preparation Example 1, except that 25 parts by weight of LiN(CF ₃ SO ₂ ) ₂ (LiTFSI) was added instead of 15 parts by weight of NaClO ₄ as an alkali metal salt in Preparation Example 1 prepared.

production example 3: acrylic ionomer (C)

An acrylic ionomer (C) was prepared in the same manner as in Preparation Example 1, except that 8 parts by weight of LiN(CF ₃ SO ₂ ) ₂ (LiTFSI) was added as an alkali metal salt in Preparation Example 2.

production example 4: Acrylic copolymer (D)

An acrylic copolymer (D) was prepared in the same manner as in Preparation Example 1, except that an alkali metal salt was not added.

production example 5: Acrylic copolymer (E)

An acrylic copolymer (E) was prepared in the same manner as in Preparation Example 2, except that an alkali metal salt was not added.

The weight average molecular weights of the acrylic ionomers and acrylic copolymers prepared in Preparation Examples 1 to 5 were measured under the following conditions using GPC. The standard polystyrene of Agilent system was used to prepare the calibration curve, and the measurement results were converted.

<Measurement conditions>

Meter: Agilent GPC (Agulent 1200 series, USA)

Column: Connect 2 PL Mixed B

Column temperature: 40°C

Eluent: Tetrohydrofuran

Flow rate: 1.0 mL/min

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

Preparation Example 1 Preparation 2 Preparation 3 Preparation 4 Preparation 5 sample A B C D E monomer mixture BA 87 77 77 87 77 MMA 5 10 10 5 10 HBA One 3 3 One 3 AA 7 10 10 7 10 alkali metal salt NaClO ₄ 15 - - - - LiTFSI - 25 8 - - weight average molecular weight
(Mw) 1.7 million 1.5 million 1.5 million 1.7 million 1.8 million

Example One

100 parts by weight of Sample A prepared as above, 0.8 parts by weight of an isocyanate-based crosslinking agent (Mitsui Takeda, D110N, Japan), 0.01 parts by weight of a crosslinking accelerator (Sigma-Aldrich, Dibutyltin dilaurate), and a silane coupling agent containing a β-cyanoacetyl group (LG A pressure-sensitive adhesive composition was prepared by mixing 0.2 parts by weight of a chemical agent, ADM812).

The prepared pressure-sensitive adhesive composition was applied to the release-treated surface of a release-treated polyethylene terephthalate film (release PET) having a thickness of 38 µm (release PET) so that the thickness after drying was 23 µm, and then dried at 110° C. for 3 minutes to form an adhesive layer did Then, the adhesive coating layer was laminated on the polarizing plate to prepare a polarizing plate including the adhesive layer.

Example 2 and 1 to 4 in comparison

A pressure-sensitive adhesive composition and a polarizing plate were prepared in the same manner as in Example 1, except that the samples shown in Table 2 were used and the content of the isocyanate-based crosslinking agent was changed as shown in Table 2 below.

division Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 sample
(parts by weight) A B C D D E 100 100 100 100 100 100 Isocyanate-based crosslinking agent 0.8 1.2 1.2 0.8 0.3 1.2 crosslinking accelerator 0.01 0.01 0.01 0.01 0.01 0.01 Silane Coupling Agent
(parts by weight) 0.2 0.2 0.2 0.2 0.2 0.2

The physical properties of the polarizing plates prepared in Examples 1 to 2 and Comparative Examples 1 to 4 were measured by the following method, and the measurement results are shown in Table 3 below.

How to measure physical properties

(1) Creep distance (Creep, μm )

A specimen was prepared by cutting the polarizing plate prepared in Examples and Comparative Examples into sizes of 10 mm in width and 10 mm in length. Then, the release PET film attached to the adhesive layer was peeled off, and a polarizing plate was attached to an alkali-free glass using a 2 kg roller according to JIS Z 0237 to prepare a measurement specimen. Then, the specimen for measurement was stored under constant temperature and humidity conditions (23° C., 50% RH) for 1 day and 4 days, respectively, and then each pushing distance using TA equipment (Texture Analyzer, Stable Microsystems, UK) was measured. Specifically, the pushing distance was measured as the distance (unit: μm) pushed by the polarizing plate from the glass substrate when the polarizing plate of the measurement specimen was pulled for 1,000 seconds under a load of 1,000 g.

(2) Evaluation of bending characteristics

After storing the polarizing plates prepared in Examples and Comparative Examples for 5 days under constant temperature and humidity conditions (23° C., 50% RH), they were cut to have a width of 35 mm and a length of 400 mm, and then they were cut to have a width of 40 mm, a length of 410 mm, and a thickness of 0.7 mm. A specimen for measurement was prepared by attaching it to the center of the phosphorus STN soda lime glass substrate in the MD (Machine direction) direction.

Then, after fixing the specimen for measurement to the vertical wall, the maximum value S ₀ of the distance from the wall to the edge of the glass substrate was measured. Then, after storing the measurement specimen at 70° C. for 72 hours, the maximum value S ₁ of the distance from the wall to the edge of the glass substrate is measured while maintaining the above conditions, and when the S ₁ -S ₀ value is 9 mm or less ○, S ₁ -S ₀ A case in which the value exceeds 9 mm was evaluated as X.

(3) Durability evaluation

The polarizing plates prepared in Examples and Comparative Examples were attached to an alkali-free glass substrate and stored in an autoclave (50° C., 5 atm) for about 20 minutes to prepare a measurement specimen.

The prepared measurement specimens were left at a temperature of 80° C. for 10 days, and then, the occurrence of bubbles or peeling was visually observed to evaluate the heat resistance durability.

In addition, the prepared measurement specimens were left for 10 days at 60° C. and 90% relative humidity, and then, the occurrence of bubbles or peeling was visually observed to evaluate the moisture and heat resistance.

<Evaluation criteria>

○: Bubbles and peeling were not observed.

X: Bubbles and/or peeling were observed.

division Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 jungle street 1 day later 520 480 470 480 leaving out 450 4 days later 450 420 400 410 920 380 bending properties ○ ○ X X ○ X heat resistance ○ ○ ○ ○ X ○ heat-and-moisture resistance ○ ○ ○ ○ ○ ○

As shown in Table 3, the polarizing plates of Examples 1 and 2 using the acrylic ionomer prepared by polymerization by adding 10 to 30 parts by weight of an alkali metal salt exhibit excellent sliding distance characteristics, bending characteristics, and durability. .

On the other hand, in the case of Comparative Example 1 using less than 10 parts by weight of the alkali metal salt, the panel warpage inhibitory effect was inferior. This is considered to be because the ionomer structure was not sufficiently formed, and a sufficient stress relaxation effect could not be obtained at a high temperature.

On the other hand, in the case of the polarizing plates of Comparative Examples 2 to 4 using the acrylic copolymer prepared without using an alkali metal salt during polymerization, at least one characteristic of the pushing distance characteristic, the bending characteristic, and the heat resistance durability compared to the polarizing plate of the Example is lowered. appear.

Claims (8)

An acrylic ionomer formed by polymerizing a mixture of an alkali metal salt with a monomer mixture containing an alkyl (meth)acrylate-based monomer, a (meth)acrylic monomer containing a hydroxyl group, and a (meth)acrylic monomer containing a carboxy group, and ,
The pressure-sensitive adhesive composition for a polarizing plate wherein the alkali metal salt is mixed in an amount of 10 to 30 parts by weight based on 100 parts by weight of the monomer mixture.
According to claim 1,
The alkali metal salt includes a metal cation selected from Li ⁺ and Na ⁺ and Cl ^- , Br ^- , I ^- , BF ₄ ^- . PF ₆ ^- , AsF ^- , ClO ₄ ^- , NO ₂ ^- , CO ₃ ^- , N(CF ₃ SO ₂ ) ₂ ^- , N(CF ₃ CO) ₂ ^- , N(C ₂ F ₅ CO) ₂ ^- , N (C ₂ F ₅ SO ₂ ) ₂ ^- , N(C ₄ F ₉ SO ₂ ) ₂ ^- , C(CF ₃ SO ₂ ) ₃ ^- , and CF ₃ SO ₃ ^- A polarizing plate consisting of an anion selected from the group consisting of adhesive composition for use.
According to claim 1,
The alkali metal salt is NaClO ₄ , LiN(CF ₃ SO ₂ ) ₂ , LiClO ₄ , LiPF ₆ or a mixture thereof.
According to claim 1,
The monomer mixture is based on 100 parts by weight of the monomer mixture,
A polarizing plate comprising 87 to 94.5 parts by weight of an alkyl (meth)acrylate-based monomer, 0.5 to 3 parts by weight of a (meth)acrylic monomer including a hydroxyl group, and 5 to 10 parts by weight of a (meth)acrylic monomer including a carboxyl group. adhesive composition for use.
According to claim 1,
The pressure-sensitive adhesive composition for a polarizing plate further comprises an isocyanate-based polyfunctional crosslinking agent.
6. The method of claim 5,
The isocyanate-based polyfunctional crosslinking agent, the pressure-sensitive adhesive composition for a polarizing plate to be included in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the acrylic ionomer.
polarizing film; and
A polarizing plate comprising an adhesive layer formed on one or both sides of the polarizing film and comprising a cured product of the adhesive composition for a polarizing plate according to any one of claims 1 to 6.
A display device comprising the polarizing plate of claim 7.