WO2017095171A1 - Complex polarizing plate and image display device including same - Google Patents

Abstract

The present invention provides a complex polarizing plate comprising: a substrate; a polarizing coating layer formed on one surface of the substrate; a photocurable adhesive layer formed on the polarizing coating layer; and a phase difference coating layer formed on the photocurable adhesive layer, wherein the absorbance in a wavelength of 400 nm of the photocurable adhesive layer is 0.5 to 1.5. The complex polarizing plate according to the present invention can ensure excellent adhesion and optical reliability between respective coating layers while also having a lightweight thin film structure.

Description

Composite polarizing plate and image display device including the same

The present invention relates to a composite polarizing plate and an image display device including the same, and more particularly, to a composite polarizing plate having a thin film-weighted structure and excellent adhesion and optical reliability, and an image display device including the same.

As the information society develops, the demand for display devices is gradually increasing in various forms. In response to this, various display devices such as liquid crystal display devices, plasma display panels, and organic light emitting diodes have been studied.

As the use of such a display device is rapidly expanded, a flexible display capable of maintaining display performance even if it is bent like a paper using a flexible material such as plastic instead of a glass substrate which is not flexible in recent years is the next generation display device. It's suddenly rising.

Republic of Korea Patent Publication No. 2008-0073252 is a liquid crystal cell; A first polarizing plate attached to one side of the liquid crystal cell and including a first polarizer and a first protective film; A second polarizing plate attached to the other side of the liquid crystal cell and including a second polarizer and a second protective film; And an adhesive for attaching the liquid crystal cell and the first polarizer or the second polarizer, wherein the first protective film is attached to an upper portion of the first polarizer of the first polarizing plate, and an adhesive is attached to the liquid crystal cell side. A flexible liquid crystal display is disclosed.

The flexible liquid crystal display is intended to achieve a thin structure by removing the protective film in contact with the liquid crystal cell of the polarizing plate, but more structurally required to achieve a thin film weight of the polarizing plate.

The present invention is to solve the above problems, one object of the present invention is to provide a composite polarizing plate excellent in adhesiveness and optical reliability while having a thin-film lightweight structure.

Another object of the present invention is to provide an image display device including the composite polarizing plate.

On the other hand, the present invention; A polarizing coating layer formed on one surface of the substrate; A photocurable adhesive layer formed on the polarizing coating layer; And a phase difference coating layer formed on the photocurable adhesive layer, the composite polarizing plate having an absorbance of 0.5 to 1.5 at a wavelength of 400 nm of the photocurable adhesive layer.

In one embodiment of the present invention, the photocurable adhesive layer may be formed from an adhesive composition comprising an acrylic monomer and a long wavelength photopolymerization initiator.

In one embodiment of the present invention, the absorption wavelength region of the long wavelength photopolymerization initiator may be in the range of 350 to 450 nm.

In one embodiment of the present invention, the long wavelength photopolymerization initiator may include a compound of Formula 1:

[Formula 1]

Where

R ₁ is hydrogen or an alkyl group of C ₁ -C ₁₀ ,

R ₂ is hydrogen or an alkyl group of C ₁ -C ₁₀ ,

m is an integer from 1 to 4,

n is an integer of 0-2.

In one embodiment of the present invention, the long wavelength photopolymerization initiator may be included in 0.5 to 10 parts by weight based on 100 parts by weight of the acrylic monomer.

On the other hand, the present invention provides an image display device including the composite polarizing plate.

The composite polarizing plate according to the present invention has a thin film-weighted structure, and has a photocurable adhesive layer having an absorbance of 0.5 or more at 400 nm wavelength, thereby securing excellent adhesion and optical reliability between UV-blocking coating layers.

1 is a cross-sectional view schematically showing a composite polarizing plate according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings the present invention will be described in more detail.

As shown in FIG. 1, a composite polarizing plate 100 according to an embodiment of the present invention includes a substrate 110; A polarizing coating layer 120 formed on one surface of the substrate; A photocurable adhesive layer 130 formed on the polarizing coating layer; And a phase difference coating layer 140 formed on the photocurable adhesive layer.

The composite polarizing plate 100 according to the exemplary embodiment of the present invention is a laminate having a complex structure of a polarizing coating layer 120 and a retardation coating layer 140 having UV blocking properties, and may implement a thin film-weighted display device. The interlayer peel force and optical reliability of 0.5 N / 25 mm or more can be ensured by providing the photocurable adhesive layer 130 whose light absorbency in 400 nm wavelength is 0.5 or more, especially 0.5-1.5 in between.

The absorbance (A / λ 400) at the 400 nm wavelength is a value that can be measured with a spectrophotometer or the like and is obtained by measuring the transmitted light intensity when light having a wavelength of 400 nm is incident on a sample (photocurable adhesive layer) as incident light.

Composite polarizing plate according to an embodiment of the present invention may have a thickness of 10 to 100㎛, preferably 10 to 60㎛.

<Polarizing Coating Layer>

In one embodiment of the present invention, the polarizing coating layer serves as an optical film, ie, a polarizer, which serves to convert incident natural light into a desired single polarization state (linear polarization state), and may be formed on at least one surface of the substrate. .

For example, the alignment film forming composition may be applied onto a substrate to impart orientation to form an alignment film layer, and the coating layer forming composition containing a liquid crystal compound and a dichroic dye may be coated on the alignment film layer to form a liquid crystal coating layer. Can be.

Such a polarizing coating layer may be formed in a thinner thickness than a conventional polarizing plate, that is, a polyvinyl alcohol-based polarizer and a polarizing plate including a protective film attached to both surfaces of the polarizer through an adhesive.

The substrate may be a film excellent in transparency, mechanical strength, thermal stability, moisture shielding, isotropy and the like. Specific examples include polyester resins such as polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate and polybutylene terephthalate; Cellulose resins such as diacetyl cellulose and triacetyl cellulose; Polycarbonate resins; Acrylic resins such as polymethyl (meth) acrylate and polyethyl (meth) acrylate; Styrene resins such as polystyrene and acrylonitrile-styrene copolymers; Polyolefin-based resins such as polyethylene, polypropylene, cyclo-based or norbornene-structured polyolefins, ethylene-propylene copolymers; Vinyl chloride-based resins; Amide resins such as nylon and aromatic polyamides; Imide resin; Polyether sulfone resin; Polyether ether ketone resins; Sulfided polyphenylene resins; Vinyl alcohol-based resins; Vinylidene chloride-based resins; Vinyl butyral resin; Allyl resins; Polyoxymethylene resin; And films composed of thermoplastic resins such as epoxy resins, and the like, and films composed of blends of the above thermoplastic resins may also be used. Moreover, the film of thermosetting resin or ultraviolet curable resin, such as (meth) acrylic-type, urethane type, acrylurethane type, epoxy type, and silicone type, can also be used.

The alignment layer forming composition may include an alignment agent, a photopolymerization initiator, and a solvent commonly used in the art.

As the alignment agent, an alignment agent conventionally used in the art may be used without particular limitation. For example, a polyacrylate-based polymer, a polyamic acid, a polyimide-based polymer, or a polymer containing cinnamate groups may be used as the alignment agent, and in the case of applying photoalignment, it is preferable to use a polymer containing cinnamate groups. . The polymer used as the alignment agent may have a weight average molecular weight of about 10,000-500,000, but is not limited thereto.

As the photopolymerization initiator, a photopolymerization initiator commonly used in the art may be used without particular limitation. For example, a benzoin compound, a benzophenone compound, an alkylphenone compound, an acylphosphine oxide compound, a triazine compound, an iodonium salt, and a sulfonium salt are mentioned. A commercial item can also be used as a photoinitiator. Specifically, Igacure 907, Igacure 184, Igacure 651, Igacure 819, Igacure 250, Igacure 369 (above, all manufactured by BASF Japan Co., Ltd.), Sakeol BZ, Sakeall Z, Sheikh all BEE (all are manufactured by Seiko Kagaku Co., Ltd.), Kayacure BP100 (made by Nihon Kayaku Co., Ltd.), Cyracure UVI-6992 (manufactured by Dow Chemical), Adeka Opto Mercury SP-152, adekaoptomer SP-170 (above, all manufactured by ADEKA), TAZ-A, TAZ-PP (above, manufactured by DKSH Japan), TAZ-104 (manufactured by Sanwa Chemical), etc. have.

As the solvent, a solvent commonly used in the art may be used without particular limitation. For example, Alcohol solvents, such as methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, propylene glycol monomethyl ether, and a phenol; Ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, propylene glycol methyl ether acetate, and ethyl lactate; Ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, and methyl isobutyl ketone; Aliphatic hydrocarbon solvents such as pentane, hexane and heptane; Nitrile solvents, such as aromatic hydrocarbon solvents, such as toluene and xylene, and acetonitrile; Ether solvents such as tetrahydrofuran and dimethoxyethane; And chlorine solvents such as chloroform and chlorobenzene. These solvents may be used alone or in combination of a plurality thereof.

The alignment layer forming composition may further include additives such as fillers, curing agents, leveling agents, adhesion promoters, antioxidants, ultraviolet absorbers, anti-agglomerating agents, chain transfer agents, and the like, as necessary.

A commercial item may be used for the said oriented film formation composition, As the specific example, ROP-108 EXP115 marketed by Rolic company is mentioned.

Application of the alignment layer forming composition may be used without limitation, for example, conventional coating methods known in the art, such as a doctor blade, a wire bar, a die coater, a comma coater, a gravure coater, a roll.

After applying the alignment layer forming composition on the base film may be carried out a drying process. In this case, drying may be performed at 120 ° C. or less, preferably 30 to 120 ° C., more preferably 50 to 120 ° C., but is not limited thereto.

After the alignment film forming composition is applied and dried as necessary, an alignment treatment is performed. The orientation treatment can adopt various methods known in the art without limitation, and preferably photocuring can be used.

The coating layer forming composition may include a liquid crystal compound and a dichroic dye having optical anisotropy and crosslinking by light or heat.

The liquid crystal compound may include, for example, a reactive liquid crystal compound (RM). Examples of the reactive liquid crystal compound (RM) include those described in Information Display 10, No. 1 (Recent Research Trends of Reactive Liquid Crystal Monomer (RM)).

The reactive liquid crystal compound refers to a monomer molecule having a liquid crystal phase, including a mesogen capable of expressing liquid crystal and a terminal group capable of polymerization. By polymerizing the reactive liquid crystal compound, it is possible to obtain a crosslinked polymer network while maintaining the aligned phase of the liquid crystal. When the reactive liquid crystal compound molecules are cooled from the clearing point, a large area domain having a structure that is better aligned at a relatively low viscosity in the liquid crystal phase may be obtained than when the liquid crystal polymer having the same structure is used.

The large area liquid crystal crosslinked network film thus formed is mechanically and thermally stable because it has a solid thin film form while maintaining properties such as optical anisotropy and dielectric constant of the liquid crystal.

A commercial item may be used as the reactive liquid crystal compound, and specific examples thereof include pario color LC242 sold by BASF. These reactive liquid crystal compounds may be used alone or in combination of a plurality thereof.

The dichroic dye refers to a dye that absorbs light of one of two polarization orthogonal components and transmits another polarization orthogonal component with respect to the determined wavelength region. In other words, the dichroic dye has a property of linearly polarizing light. As such dichroic dyes, anthraquinone dyes, phthalocyanine dyes, propyrine azo dyes, viazo dyes, and triazo dyes may be used. In particular, dichroic azo dyes are suitable.

When the dichroic dye polymerizes the reactive liquid crystal compound, the dichroic dye is dispersed between the liquid crystals and aligned in the same direction as the liquid crystals.

The coating layer forming composition is used after dilution in a solvent in order to ensure the efficiency of the coating process and uniformity of the coating layer, and preferably has a uniform dissolved in a solvent capable of dissolving the liquid crystal compound.

In addition, the reactive liquid crystal compound comprises an initiator for polymerizing and crosslinking it to prepare a coating layer forming composition. The initiator may be a known photopolymerization initiator or a thermal polymerization initiator, and the photopolymerization initiator is preferable because of easy reaction time and control. The initiator may be used in an amount of 10 wt% or less, preferably 0.1 to 5 wt%, based on the total solids of the reactive liquid crystal compound.

In addition, the reactive liquid crystal compound may further include an additive to prepare a coating layer forming composition. Additives include, for example, photosensitizers, dispersants, binders (eg, free radical polymerizable and cationic polymerizable binders), preservatives (eg, glutaraldehyde, tetramethylolacetyleneurea), silane coupling agents, leveling agents, Crosslinking agents, antioxidants, degassing agents, defoamers, viscosity modifiers, flow improvers, sedimentation inhibitors, gloss improvers, lubricants, adhesion promoters, meting agents, emulsifiers, stabilizers, hydrophobic agents, ultraviolet absorbers, treatment improvers, antistatic agents and the like can be used. .

As said ultraviolet absorber, a benzophenone type, a benzotriazole type, a benzotriazine type, a hydroxyphenyl triazine type, a benzamide type, a benzoate type, a cyanoacrylate type, a nitroaniline type, a salicylate type ( salicylates, cinnamates, oxanilides, coumarins, coumarins, flavones, dansyl amides, or quinine UV absorbers may be used. . The content of the ultraviolet absorbent may be appropriately selected within a range that does not impair the function of the polarizing coating layer.

The method of applying the coating layer forming composition is not particularly limited, and specifically, die coating, pin coating, roll coating, dispensing coating, gravure coating, or the like may be used. It is desirable to determine the type and amount of solvent depending on the coating method.

The solvent contained in the coating layer forming composition is evaporated through a drying process.

The drying is not particularly limited, and can be generally performed using a hot air dryer or a far infrared heater, and the drying temperature is usually 50 to 150 ° C, preferably 70 to 130 ° C, and the drying time is usually 30 to 600 seconds, preferably Is 60 to 300 seconds. In addition, drying may be carried out at the same temperature conditions, or may be performed while raising the temperature step by step.

After drying, photocuring is carried out by light irradiation such as ultraviolet rays or thermosetting by heat irradiation such as a heater to form a liquid crystal coating layer.

The photocuring may be used for low pressure mercury lamp, medium pressure mercury lamp, high pressure mercury lamp, ultra high pressure mercury lamp, chemical lamp, black light lamp, microwave excitation mercury lamp, metal halide lamp, etc. Use of halide lamps is preferred.

Roughness may range from 30 to 300 mW / cm 2, preferably from 30 to 250 mW / cm 2, more preferably from 30 to 200 mW / cm 2. If the roughness is less than 30mW / ㎠ the curing time is long, the productivity may be lowered, if it is more than 300mW / ㎠ it can be deformed by applying heat damage to the film due to high roughness.

0.5-10 micrometers is preferable and, as for the thickness of the said polarizing coating layer, 0.5-5 micrometers is more preferable.

<Phase difference coating layer>

In one embodiment of the present invention, the retardation coating layer plays a role of eliminating image coloring, enlarging the viewing angle, color correction, reducing light reflection, and the like.

The retardation coating layer is applied to the alignment film forming composition on the transfer film and imparting orientation to form an alignment film layer, by coating a coating layer forming composition containing a liquid crystal compound on the alignment film layer to form a liquid crystal coating layer, and then the adhesive layer and It may be formed by attaching and then removing the transfer film, but is not limited thereto.

The transfer film may be a polymer film exemplified as the substrate of the polarizing coating layer described above.

Since the alignment film forming composition, its coating, drying method, and the like are the same as described in the polarizing coating layer, the description is omitted to avoid duplication.

The composition of the coating layer forming composition is the same as described in the polarizing coating layer, except that the dichroic dye is not included. In addition, since the coating, drying and curing methods of the coating layer forming composition are the same as those described in the polarizing coating layer, the description is omitted to avoid duplication.

0.5-10 micrometers is preferable and, as for the thickness of the said retardation coating layer, 0.5-5 micrometers is more preferable.

<Photocurable adhesive layer>

In one embodiment of the present invention, the photocurable adhesive layer is interposed between the UV blocking polarizing coating layer and the UV blocking retardation coating layer, and serves to attach them to each other.

The photocurable adhesive layer may be formed by applying and curing an adhesive composition including an acrylic monomer and a long wavelength photopolymerization initiator on a polarizing coating layer or a retardation coating layer, having an absorbance at 400 nm wavelength of 0.5 or more, particularly 0.5 to 1.5.

The acrylic monomer is a (meth) acrylic compound having at least one (meth) acryloyloxy group in a molecule, and specifically, methyl (meth) acrylate, allyl methacrylate, 2-ethoxyethyl (meth) acrylate, Isodecyl (meth) acrylate, 2-dodecylthioethyl methacrylate, octyl acrylate, 2-methoxyethyl acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylic Latex, 4-hydroxybutyl (meth) acrylate, isooctyl (meth) acrylate, isodecyl (meth) acrylate, stearyl (meth) acrylate, glycidyl (meth) acrylate, tetraperfuryl ( Monofunctional, such as meth) acrylate, phenoxyethyl (meth) acrylate, urethane acrylate, aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, and isobornyl (meth) acrylate Dimer; 1,3-butanedioldi (meth) acrylate, 1,4-butanedioldi (meth) acrylate, 1,6-hexanedioldi (meth) acrylate, ethylene glycoldi (meth) acrylate, bisphenol A-ethylene Glycol diacrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (meth) Acrylate, neopentyl glycol di (meth) acrylate, dicyclopentanyldi (meth) acrylate, caprolactone modified dicyclopentenyldi (meth) acrylate, ethylene oxide modified phosphate di (meth) acrylate, bis (2 -Hydroxyethyl) isocyanurate di (meth) acrylate, di (acryloxyethyl) isocyanurate, allylated cyclohexyldi (meth) acrylate, dimethyloldicyclopentanediacrylate , Ethylene oxide-modified hexahydrophthalic acid diacrylate, tricyclodecane dimethanol diacrylate, neopentyl glycol-modified trimethylolpropane diacrylate, adamantyl bifunctional monomers such as tandi acrylate; Trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane Trifunctional monomers such as tri (meth) acrylate, tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, and glycerol tri (meth) acrylate ; Tetrafunctional monomers such as diglycerin tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate; Pentafunctional monomers such as propionic acid-modified dipentaerythritol penta (meth) acrylate; And six-functional monomers such as caprolactone-modified dipentaerythritol hexa (meth) acrylate, and the like, and among these, 1-3 functional monomers are preferable. These can be used individually or in mixture of 2 or more types.

The long wavelength photopolymerization initiator included in the adhesive composition refers to an initiator that absorbs long-wavelength active energy rays to generate radicals, and the absorption wavelength range may be, for example, in the range of 350 to 450 nm.

Such a long wavelength photopolymerization initiator can prevent the photocuring of a photopolymerizable compound such as an acrylic monomer from being inhibited due to a filter effect even when used for attachment of a UV blocking polarizing coating layer and a retardation coating layer to block ultraviolet rays of 370 nm or less. .

In one embodiment of the present invention, the long wavelength photopolymerization initiator may include a compound of Formula 1:

[Formula 1]

Where

R ₁ is hydrogen or an alkyl group of C ₁ -C ₁₀ , preferably methyl,

R ₂ is hydrogen or an alkyl group of C ₁ -C ₁₀ , preferably methyl, ethyl or isopropyl,

m is an integer from 1 to 4,

n is an integer of 0-2.

As used herein, an alkyl group of C ₁ -C ₁₀ refers to a straight or branched hydrocarbon having 1 to 10 carbon atoms, for example methyl, ethyl, n-propyl, i-propyl, n-butyl, i -Butyl, t-butyl, n-pentyl, n-hexyl, and the like.

Representative examples of the compound of Formula 1 include bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide, bis (2,4,6 -Trimethylbenzoyl) -4-methylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,5-diisopropylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2- Methylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,5-diethylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,3,5,6-tetramethylphenyl Phosphine oxide and mixtures thereof.

In addition to the above phosphine oxides, ethyl-2,4,6-trimethylbenzoylphenylphosphinate and 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 , 2,4-bistrichloromethyl-6-p-methoxystyryl-s-triazine, 2-p-methoxystyryl-4,6-bistrichloromethyl-s-triazine, 2,4 -Trichloromethyl-6-triazine, 2,4-trichloromethyl-4-methylnaphthyl-6-triazine, 2- (o-chlorophenyl) -4,5-diphenyl imidazole dimer, 2- (o-chlorophenyl) -4,5-di (m-methoxyphenyl) imidazole dimer, 2- (o-fluorophenyl) -4,5-diphenyl imidazole dimer, 2-methyl-1- [4 -(Methylthio) phenyl] -2-morphopropanone-1, diphenyl ketone benzyl dimethyl ketal, 2-hydroxy-2-methyl-1-phenyl-1-one, dimethoxy-2-phenylacetophenone, etc. It can be used as a long wavelength photopolymerization initiator.

The long wavelength photopolymerization initiator may be included in an amount of 0.5 to 10 parts by weight based on 100 parts by weight of a photopolymerizable compound such as the acrylic monomer. When the content is less than 0.5 parts by weight, curing becomes insufficient, and when it exceeds 10 parts by weight, durability may be reduced.

The long wavelength photopolymerization initiator may be used alone or in combination with a short wavelength photopolymerization initiator having an absorption wavelength range of 370 nm or less.

Specific examples of the short wavelength photopolymerization initiator include benzoin compounds, benzophenone compounds, thioxanthone compounds, triazine compounds and the like.

In addition, the adhesive composition may further include additives known in the art as needed. The kind of the additive is not particularly limited, and for example, a photosensitizer, a silane coupling agent, an adhesion promoter, a leveling agent, an ultraviolet absorber, an antioxidant, a dye, a processing aid, an ion trap, an antioxidant, a tackifier, a filler , Plasticizers, foaming inhibitors, antistatic agents, fragrances, surfactants and the like. These can be used individually or in mixture of 2 or more types.

There is no restriction | limiting in particular in the coating method of the said adhesive composition, For example, various coating methods, such as a doctor blade, a wire bar, a die coater, a comma coater, a gravure coater, can be used.

The adhesive composition is cured by irradiating active energy rays to attach the UV blocking polarizing coating layer and the UV blocking retardation coating layer.

As the light source of the active energy ray, low pressure mercury lamp, medium pressure mercury lamp, high pressure mercury lamp, ultra high pressure mercury lamp, chemical lamp, black light lamp, microwave excitation mercury lamp, metal halide lamp and the like can be used. Light irradiation intensity | strength with respect to an adhesive agent is suitably determined according to the composition of the adhesive agent, Although it does not specifically limit, It is preferable that the irradiation intensity of the wavelength range effective for activation of a polymerization initiator is 0.1-6000 mW / cm <2>. When the irradiation intensity is 0.1 mW / cm 2 or more, the reaction time does not become too long, and when 6000 mW / cm 2 or less, there is little possibility that yellowing or deterioration due to heat radiated from the light source and exotherm upon curing of the adhesive is less likely to occur. Although the light irradiation time with respect to an adhesive agent is controlled for every adhesive agent to harden | cure, it is not specifically limited, It is preferable to set so that the accumulated light amount represented as a product of the said irradiation intensity and irradiation time may be set to 10-10,000 mJ / cm <2>. When the amount of accumulated light on the adhesive is 10 mJ / cm 2 or more, the active species derived from the polymerization initiator may be generated in a sufficient amount to cure the reaction more reliably.In the case of 10,000 mJ / cm 2 or less, the irradiation time is not too long, so that the good productivity is achieved. Can be maintained.

The thickness of the photocurable adhesive layer may be adjusted according to its adhesive strength, preferably 0.1 to 10 μm, more preferably 0.1 to 5 μm.

The composite polarizing plate according to the embodiment of the present invention as described above has a thin film-weighted structure having a thickness of 10 to 100 μm, preferably 10 to 60 μm, and has excellent adhesion, as can be seen in the experimental example described later. Therefore, when the peeling force evaluation can exhibit an interlaminar peeling force of 0.5 N / 25mm or more, it is also excellent in optical reliability.

The composite polarizing plate according to the present invention can be applied to various image display devices such as electroluminescent display devices and plasma display devices as well as ordinary liquid crystal display devices. Accordingly, another embodiment of the present invention relates to an image display device including the composite polarizing plate.

Hereinafter, the present invention will be described in more detail with reference to Examples, Comparative Examples and Experimental Examples. These examples, comparative examples and experimental examples are only for illustrating the present invention, it is apparent to those skilled in the art that the scope of the present invention is not limited thereto.

Preparation Example 1 Preparation of Composition for Forming Polarizing Coating Layer

As a polymerizable liquid crystal compound, 100 parts by weight of a compound represented by the following formula, 2 parts by weight of an azo dye (NKX2029; Hayashibara Seibutsu Chemical Co., Ltd.), 2-dimethylamino-2-benzyl-1- (4-morpholino) as a polymerization initiator 6 parts by weight of phenyl) butan-1-one (Igacure 369; BASF Japan Co., Ltd.), 2 parts by weight of isopropyl thioxanthone (Nihon Seibel Heg Screw) as a photosensitizer, and a polyacrylate compound (BYK-361N) as a leveling agent; BYK-Chemical Co.) 1.2 parts by weight and 250 parts by weight of cyclopentanone were mixed with a solvent, and the obtained mixture was stirred at 80 ° C. for 1 hour to prepare a composition for forming a polarizing coating layer.

Preparation Example 2 Preparation of Composition for Retardation Coating Layer Formation

100 parts by weight of a compound represented by the following chemical formula as a polymerizable liquid crystal compound, 2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) butan-1-one (Igacure 369; BASF Japan) 6 Parts by weight, 2 parts by weight of isopropyl thioxanthone (Nihon Siebel Heg Screw) as a photosensitizer, 1.2 parts by weight of a polyacrylate compound (BYK-361N; BYK-Kemissa) as a leveling agent, 2- (2- as a UV absorber 2 parts by weight of hydroxyphenyl-benzotriazole) (Tinuvin® 99-2; BASF) and 250 parts by weight of cyclopentanone with a solvent, and the resulting mixture was stirred at 80 ° C. for 1 hour to form a phase difference coating layer. The composition was prepared.

Preparation Example 3 Preparation of Adhesive Composition

Preparation Example 3-1:

60 parts by weight of isobornyl acrylate ( A-1 , Tokyo Chemical Co.), 10 parts by weight of 4-hydroxybutyl acrylate ( A-2 , Aldrich Co.), 1,6-hexanediol diacrylate ( A-3 , 20 parts by weight of Shinnakamura, 10 parts by weight of trimethylolpropane triacrylate ( A-4 , Shinnakamura), and diphenyl- (2,4,6-trimethylbenzoyl) phosphine as a photopolymerization initiator. An adhesive composition was prepared by mixing 3 parts by weight of oxide (TPO) ( C-1 , 340 to 440 nm, BASF).

Preparation Example 3-2:

0.5 parts by weight of diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) ( C-1 , 340-440 nm, BASF) as a photopolymerization initiator and bis (2,4,6-trimethylbenzoyl)- An adhesive composition was prepared in the same manner as in Preparation Example 3-1, except that 0.5 parts by weight of phenylphosphine oxide ( C-2 , Igacure - 819, 320 to 440 nm, Ciba) was used.

Preparation Example 3-3:

1.5 parts by weight of diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) ( C-1 , 340-440 nm, BASF) as a photopolymerization initiator and bis (2,4,6-trimethylbenzoyl)- An adhesive composition was prepared in the same manner as in Preparation Example 3-1, except that 1.5 parts by weight of phenylphosphine oxide ( C-2 , Igacure - 819, 320 to 440 nm, Ciba) was used.

Preparation Example 3-4:

3 parts by weight of diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) ( C-1 , 340 to 440 nm, BASF) as a photopolymerization initiator and 1-hydroxycyclohexyl phenyl ketone ( C-3 , Igacure-184, 240 to 370nm, Ciba company) except that 1 part by weight was used in the same manner as in Preparation Example 3-1, to prepare an adhesive composition.

Preparation Example 3-5:

2 parts by weight of diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) ( C-1 , 340 to 440 nm, BASF) as a photopolymerization initiator and 1-hydroxycyclohexyl phenyl ketone ( C-3 , Igacure-184, 240 to 370nm, Ciba company) except that 2 parts by weight was used in the same manner as in Preparation Example 3-1, to prepare an adhesive composition.

Preparation Example 3-6:

1 part by weight of diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) ( C-1 , 340-440 nm, BASF) as a photopolymerization initiator and 1-hydroxycyclohexyl phenyl ketone ( C-3 , Igacure-184, 240 to 370nm, Ciba company), except that 3 parts by weight was used in the same manner as in Preparation Example 3-1, to prepare an adhesive composition.

Preparation Example 3-7:

40 parts by weight of isobornyl acrylate ( A-1 , Tokyo Chemical Co., Ltd.), 40 parts by weight of trimethylolpropane triacrylate ( A-4 , Shin-Nakamura Co.) and pentaerythritol triacrylate ( A-5 ) as the photopolymerizable compound. , Unwon Corporation) 20 parts by weight, and 3 parts by weight of diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) ( C-1 , 340 to 440 nm, BASF) as a photopolymerization initiator and 1-hydride An adhesive composition was prepared by mixing 1 part by weight of oxycyclohexyl phenyl ketone ( C-3 , Igacure - 184, 240 to 370 nm, Ciba).

Preparation Example 3-8:

50 parts by weight of isobornyl acrylate ( A-1 , Tokyo Chemical Co., Ltd.), 40 parts by weight of trimethylolpropane triacrylate ( A-4 , Shin-Nakamura Co.), pentaerythritol triacrylate ( A-5) , Miwon Corporation) 10 parts by weight and 3 parts by weight of diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) ( C-1 , 340 to 440 nm, BASF) as a photopolymerization initiator and 1-hydroxy An adhesive composition was prepared by mixing 1 part by weight of cyclohexyl phenyl ketone ( C-3 , Igacure - 184, 240 to 370 nm, Ciba).

Preparation Example 3-9:

60 parts by weight of isobornyl acrylate ( A-1 , Tokyo Chemical Co., Ltd.), 30 parts by weight of trimethylolpropane triacrylate ( A-4 , Shin-Nakamura Co., Ltd.), pentaerythritol triacrylate ( A-5) , Miwon Corporation) 10 parts by weight and 3 parts by weight of diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) ( C-1 , 340 to 440 nm, BASF) as a photopolymerization initiator and 1-hydroxy An adhesive composition was prepared by mixing 1 part by weight of cyclohexyl phenyl ketone ( C-3 , Igacure - 184, 240 to 370 nm, Ciba).

Preparation Example 3-10:

40 parts by weight of isobornyl acrylate ( A-1 , Tokyo Chemical Co., Ltd.), 10 parts by weight of 4-hydroxybutyl acrylate ( A-2 , Aldrich Co.), trimethylolpropane triacrylate ( A-4 , Shinnakamura) 30 parts by weight and 20 parts by weight of pentaerythritol triacrylate ( A-5 , Miwon Corporation), and diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) as a photopolymerization initiator. 3 parts by weight of ( C-1 , 340 to 440 nm, BASF) and 1 part by weight of 1-hydroxycyclohexyl phenyl ketone ( C-3 , Igacure - 184, 240 to 370 nm, Ciba) were prepared to prepare an adhesive composition. It was.

Preparation Example 3-11:

30 parts by weight of 4-hydroxybutyl acrylate ( A-2 , Aldrich), 30 parts by weight of 1,6-hexanediol diacrylate ( A-3 , Shin-Nakamura) as a photopolymerizable compound, trimethylolpropane triacryl 30 parts by weight of latex ( A-4 , Shin-Nakamura) and 10 parts by weight of pentaerythritol triacrylate ( A-5 , Miwon Corporation), and diphenyl- (2,4,6-trimethylbenzoyl) force as a photopolymerization initiator 3 parts by weight of fin oxide (TPO) ( C-1 , 340 to 440 nm, BASF) and 1 part by weight of 1-hydroxycyclohexyl phenyl ketone ( C-3 , Igacure - 184, 240 to 370 nm, Ciba) To prepare an adhesive composition.

Preparation Example 3-12:

40 parts by weight of isobornyl acrylate ( A-1 , Tokyo Chemical Co., Ltd.), 10 parts by weight of 4-hydroxybutyl acrylate ( A-2 , Aldrich Co.), 1,6-hexanediol diacrylate ( A-3 , 20 parts by weight of Shin-Nakamura Co., Ltd. and 30 parts by weight of trimethylolpropane triacrylate ( A-4 , Shin-Nakamura Co.), and bis (2,4,6-trimethylbenzoyl) -phenylphosphine as a photopolymerization initiator. An adhesive composition was prepared by mixing 3 parts by weight of oxide ( C-2 , Igacure - 819, 320 to 440 nm, Ciba).

Preparation Example 3-13:

Preparation Example 3-12 except that 1.5 parts by weight of bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide ( C-2 , Igacure - 819, 320 to 440 nm, Ciba) was used as the photopolymerization initiator. By following the same method as the adhesive composition was prepared.

Preparation Example 3-14:

Same as Preparation Example 3-12 except that 3 parts by weight of diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) ( C-1 , 340 to 440 nm, BASF) was used as the photopolymerization initiator. The method was carried out to prepare an adhesive composition.

Preparation Example 3-15:

Same as Preparation Example 3-12, except that 1.5 parts by weight of diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) ( C-1 , 340 to 440 nm, BASF) was used as the photopolymerization initiator. The method was carried out to prepare an adhesive composition.

Comparative Preparation Example 3-1:

40 parts by weight of isobornyl acrylate ( A-1 , Tokyo Chemical Co., Ltd.), 10 parts by weight of 4-hydroxybutyl acrylate ( A-2 , Aldrich Co.), 1,6-hexanediol diacrylate ( A-3 , 20 parts by weight of Shin-Nakamura, and 30 parts by weight of trimethylolpropane triacrylate ( A-4 , Shin-Nakamura), and 1-hydroxycyclohexyl phenyl ketone ( C-3 , Igacure) as a photopolymerization initiator. -184, 240 to 370nm, Ciba) 3 parts by weight of the mixture to prepare an adhesive composition.

Examples and Comparative Examples: Preparation of Composite Polarizing Plates

Example 1:

(1) Formation of Polarizing Plate

ROP-108 EXP115 (Rolic Co., Ltd.) was applied on a 25-μm-thick triacetyl cellulose-based film to a thickness of 1 μm and then exposed to light (250 mJ / cm ² ) to form an alignment layer. Thereafter, the composition for forming a polarizing coating layer of Preparation Example 1 was applied and dried, and cured by UV irradiation at 40 mW / cm 2 for 1 minute to form a polarizing coating layer having a thickness of 4.5 μm.

(2) Formation of Retardation Coating Layer

ROP-108 EXP115 (Rolic Co., Ltd.) was applied on a PET transfer film having a thickness of 40 μm to a thickness of 1 μm, and exposed to light (250 mJ / cm ² ) to form an alignment layer. Then, the composition for forming a phase difference coating layer of Preparation Example 2 was applied by a die coating method, dried, and cured by UV irradiation at 40 mW / cm 2 for 1 minute to form a phase difference coating layer having a thickness of 4 μm.

(3) Formation of Photocurable Adhesive Layer

The adhesive composition of Preparation Example 3-1 was applied on the polarizing coating layer, the retardation coating layer and the transfer film were laminated on the applied adhesive composition, and then irradiated with UV to form an adhesive layer having a thickness of 1 μm. Thereafter, the transfer film was peeled off to prepare a composite polarizing plate.

Examples 2-15 and Comparative Example 1:

Except for using the adhesive composition of Preparation Examples 3-2 to 3-15 and Comparative Preparation Example 3-1, the same procedure as in Example 1 was carried out to produce a composite polarizing plate.

Experimental Example 1: Measurement of Absorbance (A / λ400)

The adhesive compositions prepared in Production Examples 3-1 to 3-15 and Comparative Production Example 3-1 were each applied onto a 50 µm thick TAC film, and UV was irradiated to form an adhesive layer having a thickness of 1 µm. The absorbance of the adhesive layer was measured at 400 nm using a UV spectrophotometer (UV2450, manufactured by Shimadzu Corporation), and the results are shown in Table 1 below.

Experimental Example 2: Evaluation of Peel Force and Reliability

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

(1) Peel force evaluation

After leaving the prepared composite polarizing plate at room temperature for 1 hour, the bonding was performed by using a hand roller on a soda glass using a pressure-sensitive adhesive, and then bonded by an autoclave treatment at a pressure of 2 atm, a temperature of 50 ° C., and a time of 20 minutes. Bubbles generated at the time were removed. In the configuration of soda glass / adhesive / composite polarizing plate, insert a knife between the polarizing coating layer and the retardation coating layer of the composite polarizing plate in the soda glass direction and apply 180 ^° peel force (N / 25mm) on the adhesive layer side when peeling the polarizing plate using autograph Peel force was evaluated by measuring at a speed of 300 mm / min.

(2) optical reliability evaluation

The polarizing plates prepared in Examples and Comparative Examples were cut to A4 size, and then bonded to glass with an acrylic adhesive to prepare a specimen.

After the prepared specimens were allowed to stand in an oven at 80 ° C. for 500 hours, the samples were evaluated based on the initial polarization degree of the polarizing plate and the change rate relative to the front luminance.

<Standard>

○: change rate within ± 5% of initial polarization degree and front luminance

△: change rate within ± 10% of initial polarization degree and front luminance

×: rate of change of ± 10% or more relative to the initial polarization degree and the front luminance

Table 1

As shown in Table 1, the composite polarizing plates of Examples 1 to 15 according to the present invention are provided with an adhesive layer having an absorbance of 0.5 or more at 400 nm and higher than that of the composite polarizing plate of Comparative Example 1 having an absorbance at 400 nm. Not only the adhesion but also the optical reliability was excellent.

Having described the specific part of the present invention in detail, it is apparent to those skilled in the art that this specific technology is only a preferred embodiment, which is not intended to limit the scope of the present invention. Do. Those skilled in the art to which the present invention pertains will be able to make various applications and modifications within the scope of the present invention based on the above contents.

Therefore, the substantial scope of the present invention will be defined by the appended claims and equivalents thereof.

Claims (9)

1. materials;

   A polarizing coating layer formed on one surface of the substrate;

   A photocurable adhesive layer formed on the polarizing coating layer; And

   A composite polarizing plate comprising a phase difference coating layer formed on the photocurable adhesive layer,

   A composite polarizing plate having an absorbance of 0.5 to 1.5 at a wavelength of 400 nm of the photocurable adhesive layer.
2. The composite polarizing plate of claim 1, wherein the photocurable adhesive layer is formed from an adhesive composition comprising an acrylic monomer and a long wavelength photopolymerization initiator.
3. The composite polarizing plate of claim 2, wherein an absorption wavelength region of the long wavelength photopolymerization initiator is in a range of 350 nm to 450 nm.
4. The composite polarizing plate of claim 2, wherein the long wavelength photopolymerization initiator comprises a compound of Formula 1

   [Formula 1]

   

   Where

   R ₁ is hydrogen or an alkyl group of C ₁ -C ₁₀ ,

   R ₂ is hydrogen or an alkyl group of C ₁ -C ₁₀ ,

   m is an integer from 1 to 4,

   n is an integer of 0-2.
5. The method of claim 4, wherein

   R ₁ is methyl,

   R ₂ is methyl, ethyl or isopropyl.
6.  The composite polarizing plate of claim 2, wherein the long wavelength photopolymerization initiator is included in an amount of 0.5 to 10 parts by weight based on 100 parts by weight of the acrylic monomer.
7. The composite polarizing plate of claim 1, wherein the photocurable adhesive layer has a peel force of 0.5 N / 25 mm or more.
8. The composite polarizing plate according to claim 1, wherein the thickness is in the range of 10 to 100 μm.
9. An image display device comprising the composite polarizing plate according to any one of claims 1 to 8.

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