KR102096980B1 - Polarizing plate - Google Patents

Abstract

The present invention relates to a polarizing plate, and more specifically, at least one surface of the polarizer attached to the photocurable adhesive containing a photo-cationic polymerizable compound having a thickness of 30 μm or more and an elasticity ratio of 10 Gpa / (gcm ^-3 ) or more. By doing so, it has a remarkably improved water resistance, and is excellent in durability even when exposed to high humidity for a long period of time, minimizes changes in optical characteristics, and at the same time, relates to an excellent polarizing plate and an image display device including the same.

Description

Polarizing plate and image display device including same {POLARIZING PLATE}

The present invention relates to a polarizing plate and an image display device including the same.

With the development of various image display devices such as liquid crystal display (LCD) and plasma display (PDP), research has been conducted to provide a polarizing plate with high polarization and transmittance to provide an image with high luminance and color reproducibility. It has been. In general, the polarizing plate is a polyvinyl alcohol (PVA) polarizer dyed with a dichroic dye or iodine, and a basic structure in which a protective film of cellulose (Triacetyl cellulose, TAC) is laminated to protect both sides of the polarizer. In accordance with the display device, a retardation plate, a viewing angle compensation film, and a brightness enhancement film may be additionally stacked on the protective film.

The polyvinyl alcohol-based polarizer of the polarizing plate configured as described above is thermodynamically very unstable and susceptible to moisture, and since the TAC protective film has a large moisture absorption and moisture permeability, the polarizer contracts when the polarizer is exposed to high temperature and high humidity for a long time, resulting in dimensional changes. There is a problem in that the absorption axis of the polarizer is also distorted, and color fading occurs.

Korean Patent Publication No. 2009-82197 discloses a polarizer protective film, a polarizing plate, and an image display device, but did not provide an alternative to the above problems.

Korean Patent Publication No. 2009-82197

It is an object of the present invention to provide a polarizing plate capable of significantly improving water resistance and maintaining excellent adhesion and optical properties even in a humid environment.

An object of the present invention is to provide a polarizing plate that can also have excellent flexibility.

An object of the present invention is to provide an image display device having a polarizing plate that can replace the cover glass, making the film thinner and lighter, and exhibiting flexibility.

1. A polarizing plate comprising a protective glass having a thickness of 30 µm or more and an elasticity ratio of 10 Gpa / (gcm ^-3 ) or more attached to a photocurable adhesive containing a photocationic polymerizable compound on at least one surface of a polarizer.

2. In the above 1, wherein the polarizer has a contraction force of 3 N / 2mm or less, the polarizing plate.

3. In the above 1, wherein the protective glass has a moisture permeability of 1 g / m ² day or less, a polarizing plate.

4. In the above 1, wherein the photo-cationic polymerizable compound comprises at least one of an aliphatic epoxy compound and an alicyclic epoxy compound, a polarizing plate.

5. In the above 4, wherein the photo-cationic polymerizable compound is neopentyl glycol diglycidyl ether, 2-ethylhexyl glycidyl ether, 1,4-butanediol diglycidyl ether and (3 ', 4 '-Epoxycyclohexane) methyl 3,4-epoxy cyclohexyl carboxylate One or more selected from the group consisting of, polarizing plate.

6. In the above 1, wherein the light-curable adhesive further comprises a photo-radical polymerizable compound, a polarizing plate.

7. In the above 6, wherein the photo-radical polymerizable compound is 30% by weight or less of the total weight of the polymerizable compound, a polarizing plate.

8. In the above 1, wherein the photocurable adhesive is 80 ℃ elastic modulus is 500Mpa to 2000 Mpa, a polarizing plate.

9. An image display device comprising the polarizing plate of any one of 1 to 8 above.

10. The image display device according to the above 9, wherein the polarizing plate is provided on the viewer side, and the protective glass of the polarizing plate is used as a cover glass.

The polarizing plate of the present invention has significantly improved water resistance by using glass as a protective film. Accordingly, it is excellent in durability even when exposed to high humidity for a long time, it is possible to minimize the change in optical properties.

At the same time, the polarizing plate of the present invention has excellent bendability, and is excellent in crack resistance to bending.

The polarizing plate of the present invention includes a protective glass, which can replace the cover glass in the image display device, and can be utilized as a thinner and lighter flexible image display device.

The present invention has significantly improved water resistance by including a protective glass having a thickness of 30 µm or more and an elasticity ratio of 10 Gpa / (gcm ^-3 ) or more attached to a photocurable adhesive containing a photo cationic polymerizable compound on at least one surface of a polarizer, It relates to an excellent polarizing plate and an image display device including the same, which are excellent in durability, minimize changes in optical characteristics, and have flexibility in the case of long exposure to high humidity conditions.

Hereinafter, the present invention will be described in detail.

The polarizing plate of the present invention includes a protective glass having a thickness of 30 μm or more and an elasticity ratio of 10 Gpa / (gcm ^-3 ) or more attached to a photocurable adhesive containing a photo-cationic polymerizable compound on at least one surface of the polarizer.

Polarizer protective films such as polarizers and TACs generally shrink in a high temperature and high humidity environment. On the other hand, the protective glass according to the present invention does not shrink, but if only the polarizer is largely contracted, the thermal shock durability is lowered, so that there is a possibility of cracking of the polarizing plate. Therefore, it is preferable that the polarizer according to the present invention is a low-shrink polarizer whose shrinking force is suppressed. For example, the shrinkage force may be 3 N / 2 mm or less. When the shrinkage force is more than 3 N / 2mm, a crack may occur when the polarizing plate obtained by bonding the polarizer to the protective glass is exposed to a heat shock environment for a long time. Specifically, it may be greater than 1 N / 2mm to 3 N / 2mm or less.

The polarizer may be manufactured through a process including steps such as swelling, dyeing, crosslinking, stretching, complementary color, and drying the film for forming a polarizer.

The number of repetitions, process conditions, and the like of each manufacturing step of the polarizer are not particularly limited as long as they do not depart from the object of the present invention, and the stretching step may be performed as an independent step or simultaneously with one or more of the swelling, dyeing and crosslinking steps. It might be.

The film for forming a polarizer is not particularly limited, and the above-described film can be exemplified, and preferably a polyvinyl alcohol-based film.

Hereinafter, each process condition is specifically illustrated, but is not limited thereto.

The swelling step is immersed in a swelling tank filled with an aqueous solution for swelling prior to dyeing the unstretched polarizer forming film, thereby removing impurities such as dust or anti-blocking agents deposited on the surface of the polarizer forming film and removing the polarizer forming film. It is a step to improve physical properties of the polarizer by swelling to improve the stretching efficiency and prevent staining non-uniformity.

As an aqueous solution for swelling, water (pure water, deionized water) can be used alone, and a small amount of glycerin or potassium iodide can be added to improve the processability of the polymer film.

When glycerin and potassium iodide are included, the content is not particularly limited, and may be, for example, 5% by weight or less and 10% by weight or less of the total weight of the aqueous solution for swelling.

The temperature of the swelling bath is not particularly limited, and may be, for example, 20 to 45 ° C, and preferably 20 to 40 ° C. When the temperature of the swelling tank is within the above range, the stretching and dyeing efficiency is excellent afterwards, and expansion of the film due to excessive swelling can be prevented.

The time for performing the swelling step (swelling time of the swelling tank) is not particularly limited, and may be, for example, 180 seconds or less, preferably 90 seconds or less. When the swelling bath immersion time is within the above range, it is possible to suppress excessive swelling and becoming saturated, preventing breakage due to softening of the film for forming a polarizer, and uniformly adsorbing iodine in the dyeing step to improve polarization. You can.

The swelling step and the stretching step may be performed together, and in this case, the stretching ratio may be about 1.1 to 3.5 times, preferably 1.5 to 3.0 times. When the stretching ratio is less than 1.1 times, wrinkles may occur, and when it exceeds 3.5 times, initial optical characteristics may be deteriorated.

The dyeing step is a step of adsorbing iodine to the polarizer forming film by immersing the polarizer forming film in a dyeing tank filled with a dichroic material, for example, a dye containing iodine.

The dyeing solution may further include water, a water-soluble organic solvent, or a mixed solvent and iodine. The concentration of iodine may be 0.4 to 400 mmol / L in the dyeing solution, preferably 0.8 to 275 mmol / L, more preferably 1 to 200 mmol / L.

The dyeing solution may further include iodide as a dissolution aid for improving dyeing efficiency.

The type of iodide is not particularly limited, and examples thereof include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, barium iodide, calcium iodide, titanium iodide, and the like. , Potassium iodide is preferred in view of its high solubility in water. These may be used alone or in combination of two or more.

The content of the iodide is not particularly limited, for example, may be 0.01 to 10% by weight of the total weight of the dyeing solution, preferably 0.1 to 5% by weight.

The dyeing solution used in the dyeing step may further include a boric acid compound. The dyeing solution may include a boric acid compound, thereby improving the residence time of the boric acid compound before performing a crosslinking reaction, thereby increasing the rate of formation of the dichroic agent on the polarizer forming film. Accordingly, the color durability of the polarizer can be improved, and the polarization degree is improved.

The concentration of the boric acid compound in the dyeing solution is not particularly limited, but may be, for example, 0.3 to 5% by weight of the total weight of the dyeing solution, preferably 0.5 to 3% by weight. When the concentration of the boric acid compound in the dyeing solution is less than 0.3% by weight, the effect of increasing the formation of iodine complex decreases, and when it exceeds 5% by weight, cutting may occur due to an increase in stress.

The type of the boric acid compound is not particularly limited. For example, the boric acid compound may include boric acid, sodium borate, potassium borate, lithium borate, and the like, preferably boric acid. These may be used alone or in combination of two or more.

The temperature of the dyeing bath is not particularly limited, and may be, for example, 5 to 42 ° C, and preferably 10 to 35 ° C.

The time for immersing the film for forming the polarizer in the dyeing tank is not particularly limited, and may be, for example, 1 to 20 minutes, and preferably 2 to 10 minutes.

The stretching step may be performed together with the dyeing step, and in this case, the stretching ratio may be 1.01 to 2.0 times, preferably 1.1 to 1.8 times.

In addition, the cumulative stretching ratio of the polarizer up to the swelling and stretching step is preferably 1.2 to 4.0 times. When the cumulative stretching ratio is less than 1.2 times, wrinkles may occur on the film, and when it exceeds 4.0 times, initial optical properties may be deteriorated.

The crosslinking step is a step of fixing the adsorbed iodine molecule by immersing the dyed polarizer-forming film in the crosslinking solution so that the dyeability by the iodine molecule that is physically adsorbed is not lowered by the external environment.

The crosslinking solution used in the crosslinking step contains a boric acid compound. The crosslinking solution may include a boric acid compound, thereby improving crosslinking efficiency, suppressing wrinkles in the film during the process, and forming an orientation of a dichroic material to improve optical properties.

Dichroic dyes are not often eluted in a humid environment, but when iodine cross-linking reaction is unstable, iodine molecules are often dissolved or sublimed depending on the environment, so a sufficient cross-linking reaction is required.

The crosslinking step according to the present invention may be performed as a first crosslinking step and a second crosslinking step, and a boric acid compound may be included in the crosslinking solution used in at least one of the crosslinking steps.

The concentration of the boric acid compound in the crosslinking solution is 2 to 4.5% by weight, preferably 2.5 to 3.8% by weight. If the concentration of the boric acid compound in the number of crosslinking liquids is less than 2.5% by weight, the polarization degree decreases, and if it exceeds 3.8% by weight, there is a problem that the shrinking force increases.

The boric acid compound may be the same one used in the dyeing step.

The crosslinking solution may include water used as a solvent and an organic solvent that is mutually soluble together with water, and may further include potassium iodide to prevent uniformity of polarization in the polarizer plane and desorption of dyed iodine.

The concentration of potassium iodide in the crosslinking solution is 11 to 13% by weight, preferably 12 to 13% by weight. If the concentration of potassium iodide in the crosslinking solution is less than 11% by weight, the polarization degree decreases, and if it exceeds 13% by weight, heat resistance decreases, and reddening may occur when exposed to high temperature for a long time.

In addition, the crosslinking solution may further include the above-mentioned iodide within the scope of not impairing the object of the present invention.

The temperature of the crosslinking bath is not particularly limited, but may be, for example, 20 to 70 ° C, and preferably 40 to 60 ° C.

The time for immersing the film for forming the polarizer in the crosslinking bath is not particularly limited, and may be, for example, 1 second to 15 minutes, and preferably 5 seconds to 10 minutes.

The stretching step may be performed together with the crosslinking step, and in this case, the stretching ratio of the first crosslinking step may be 1.4 to 3.0 times, and preferably 1.5 to 2.5 times. In addition, the stretching ratio of the second cross-linking step may be 1.01 to 2.0 times, preferably 1.2 to 1.8 times.

The cumulative stretching ratio of the first crosslinking step and the second crosslinking step may be 1.5 to 5.0 times, and preferably 1.7 to 4.5 times. When the cumulative stretching ratio is less than 1.5 times, the synergistic effect of crosslinking efficiency may be insufficient, and when it exceeds 5.0 times, the film may break due to excessive stretching and production efficiency may be reduced.

The stretching step may be performed with at least one of the swelling step, the dyeing step, the crosslinking step, or may be performed in air or an inert gas while transferring the film after the steps, as described above, between or after the steps. In addition, it may be performed as an independent stretching step using a separate stretching tank filled with the stretching liquid. Alternatively, the film for forming the unstretched polarizer may be stretched in air or an inert gas before the swelling step, and then the film may be swelled, dyed, crosslinked, washed with water, and dried.

Stretching may be performed in one step, or may be performed in two or more steps, but is preferably performed in two or more steps. Stretching can be performed by, for example, placing a difference in the peripheral speed of the nip roll. Also, as in the swelling step, expander rolls, spiral rolls, crown rolls, cross guiders, bend bars and the like can be installed in the bath and / or in the bath entrance.

The total cumulative stretching ratio is preferably 4.0 to 7.0 times, and in this specification, "cumulative stretching ratio" means a value multiplied by the stretching ratios of each step.

The complementary color step is a step of adjusting the color by immersing the film that has undergone the crosslinking step in a complementary solution containing a boric acid compound and iodide.

The complementary solution used in the complementary color step contains a boric acid compound.

The boric acid compound may be the same one used in the dyeing step.

The concentration of the boric acid compound in the complementary solution is 1.5 to 2.5% by weight, preferably 1.8 to 2.2% by weight. When the concentration of the boric acid compound in the complementary solution is less than 1.5% by weight, the iodine orientation cannot be improved, so the effect of suppressing color change and improving durability is negligible, and when it exceeds 2.5% by weight, the thermal shock resistance decreases.

The complementary solution may include water used as a solvent and an organic solvent that is mutually soluble together with water, and further includes potassium iodide to prevent uniformity of polarization in the polarizer plane and desorption of dyed iodine.

The concentration of potassium iodide in the complementary solution is 4 to 8% by weight, preferably 5 to 7% by weight. When the potassium iodide concentration is less than 4% by weight, the polarization degree decreases, and if it exceeds 8% by weight, heat resistance decreases, and reddening may occur when exposed to high temperatures for a long time.

By adjusting the concentration of the boric acid compound and potassium iodide in the crosslinking solution and the concentration of the boric acid compound and potassium iodide in the complementary solution in the above-described range, the weight ratio (iodine element / potassium element) of the iodine element and potassium element in the prepared polarizer is 0.12 to 0.18 It can be made so that the boron element content is 3 to 4.5% by weight. The advantages according to this are as described above.

When the dyeing solution of the dyeing step includes the boric acid compound in the above-described concentration range, it may be easier to control the above-described preferred contractile force range.

In addition, the complementary liquid may further include the aforementioned iodide within the scope of not impairing the object of the present invention.

Additionally, the second stretching of the film for forming the polarizer may be performed in the complementary color step.

By performing the second stretching, the orientation of the dichroic material complex can be increased to improve stability, and accordingly, the polarizer manufactured by the method of the present invention is excellent in color durability by minimizing decomposition of the complex even after prolonged exposure to high temperature. .

The second stretching may be performed at a stretching ratio of 1.01 to 1.1 times. If the draw ratio is less than 1.01 times, the effect of improving the orientation of the dichroic material complex is insignificant, and if it exceeds 1.1 times, the film may break due to excessive stretching.

The temperature of the complementary tone is 20 to 70 ° C, and the immersion time of the film for forming a polarizer in the complementary tone may be 1 second to 15 minutes, preferably 5 seconds to 10 minutes.

If necessary, the polarizer may be further subjected to a water washing step after the complementary color is completed.

The washing step is a step of removing the unnecessary residue attached to the polarizer forming film in the previous steps by immersing the film for forming the polarizer whose complementary color is completed in a washing tank filled with a washing solution.

The aqueous solution for washing with water may be water (deionized water), and iodide may be further added thereto. As the iodide, the same one used in the dyeing step can be used, and among these, sodium iodide or potassium iodide is preferably used. The content of iodide is not particularly limited, and may be, for example, 0.1 to 10 parts by weight of the total weight of the aqueous solution for washing, preferably 3 to 8 parts by weight.

The temperature of the water bath is not particularly limited, and may be, for example, 10 to 60 ° C, and preferably 15 to 40 ° C.

The washing step may be omitted, and may be performed whenever previous steps such as a dyeing step, a crosslinking step, a stretching step, or a complementary color step are completed. Also, it may be repeated one or more times, and the number of repetitions is not particularly limited.

The drying step is a step of drying the washed film for forming a polarizer, and improving the orientation of the iodine molecule dyed by neck-in by drying to obtain a polarizer having excellent optical properties.

As a drying method, methods such as natural drying, air drying, heat drying, microwave drying, and hot air drying can be used. Recently, microwave treatment to activate and dry only the water in the film has been newly used. Treatment is mainly used.

The temperature during hot air drying is not particularly limited, but is preferably performed at a relatively high temperature to increase stress relaxation of the polarizer, for example, may be 30 to 100 ° C, preferably 60 ° C to 100 ° C, more preferably It may be 80 ℃ to 100 ℃, most preferably 90 ℃ to 100 ℃.

The execution time of the hot air drying is not particularly limited, and may be performed, for example, for 1 to 10 minutes.

The thickness of the polarizer prepared as described above may be 5 to 40㎛.

The polarizer according to the present invention may have a water contact angle of 50 ° or more.

A protective glass is attached to at least one surface of the polarizer.

The protective glass has a thickness of 30 µm or more. If the thickness is less than 30 μm, cracks are generated when bonding to the photocurable adhesive layer. After manufacturing the polarizing plate by bonding the polarizer and the protective film, it is usually cut to the desired product size, which is usually performed with a super cutter. If the thickness of the protective glass according to the present invention is greater than 100 μm, fracture may occur during cutting with a super cutter, and therefore, preferably, the thickness of the protective glass may be 30 μm to 100 μm.

The protective glass has an elasticity ratio of 10 Gpa / (gcm ^-3 ) or more. When the elasticity ratio is less than 10 Gpa / gcm ^-3 , cracks are generated upon bonding to the photocurable adhesive layer. For the same purpose, it may be preferably 10 to 100 Gpa / (gcm ^-3 ) for suppressing breakage during cutting.

The elasticity ratio can be expressed by Equation 1 below.

[Equation 1]

Elasticity ratio = Young's Moudulus (Gpa) / Density (g / cm ³ )

The protective glass according to the present invention is not particularly limited as long as it satisfies the above conditions, but preferably an alkali-free protective glass can be used. When the alkali component is included, the red component may occur when the alkali component is moved toward the polarizer during durability evaluation.

In addition, preferably, the protective glass according to the present invention may have a moisture permeability of 1 g / m ² day or less. In such a case, the degree of moisture permeability is low, so the effect of improving water resistance is remarkable.

The protective glass is attached with a photocurable adhesive comprising a photo cationic polymerizable compound.

When using an aqueous adhesive, curls or cracks may occur in the polarizer or the protective glass due to heat applied during the drying process of the adhesive. However, the present invention can solve the heat and cracking problem by attaching the protective glass with a photocurable adhesive. And by including a photocationic polymerizable compound, excellent moisture and heat resistance can also be exhibited.

The photo-curable adhesive may have an elasticity modulus of 80 ° C to 500 to 2000Mpa. If the modulus of elasticity is less than 500 Mpa, the ability to suppress the shrinkage of the polarizer is insufficient, and when exposed to heat for a long time in a heat shock environment, cracking of the polarizing plate may occur, and if it is more than 2000 Mpa, the adhesive strength may deteriorate.

The photocurable adhesive includes a photopolymerizable compound including a photo cationic polymerizable compound and a photopolymerization initiator.

Examples of the photocationic polymerizable compound include bisphenol-type epoxy compounds such as bisphenol-A epoxy compounds and bisphenol-F epoxy compounds; Novolac-type epoxy compounds such as phenol novolac-type epoxy compounds and cresol novolac-type epoxy compounds; Aliphatic epoxy compound, alicyclic epoxy compound, aromatic epoxy compound, naphthalene type epoxy compound, polyfunctional epoxy compound, biphenyl type epoxy compound, glycidyl ether type epoxy compound, glycidyl ester type epoxy compound, glycidylamine type Epoxy compounds; Alcohol type epoxy compounds such as hydrogenated bisphenol A type epoxy compounds; Halogenated epoxy compounds such as brominated epoxy compounds; Epoxy group-containing compounds such as rubber-modified urethane resins, urethane-modified epoxy compounds, epoxidized polybutadiene, epoxidized styrene-butadiene-styrene block copolymers, epoxy group-containing polyester resins, epoxy group-containing polyurethane resins, and epoxy group-containing acrylic resins; Phenoxymethyloxetane, 3,3-bis (methoxymethyl) oxetane, 3,3-bis (phenoxymethyl) oxetane, 3-ethyl-3- (phenoxymethyl) oxetane, 3-ethyl- 3- (2-ethylhexyloxymethyl) oxetane, 3-ethyl-3-{[3- (triethoxysilyl) propoxy] methyl} oxetane, phenol novolac oxetane, 1,4-bis {[ Oxetanyl group-containing compounds such as (3-ethyl3-oxetanyl) methoxy] methyl} benzene; These etc. are mentioned, These can be used individually or in mixture of 2 or more types. In terms of exhibiting excellent elastic modulus and adhesion, preferably, an aliphatic epoxy compound, an alicyclic epoxy compound, and the like can be mentioned.

Specific examples of preferred aliphatic epoxy compounds include neopentyl glycol diglycidyl ether (Aldrich), 2-ethylhexyl glycidyl ether (Aldrich), 1,4-butanediol diglycidyl ether (Aldrich) , 1,6-hexanediol diglycidyl ether (Aldrich), 1,2-propanediol diglycidyl ether (Aldrich), and the like, and specific examples of the alicyclic epoxy compound are 1 , 4-cyclohexanedimethanol diglycidyl ether (Aldrich), (3 ', 4'-epoxycyclohexane) methyl 3,4-epoxy cyclohexyl carboxylate (Daicel, Celloxide 2021P), 1,2- Epoxy-4-vinylcyclohexane (Daicel, Celloxide 2000), vinyl cyclohexane dioxide (Union Carbide ERL-4206), nimonene diepoxide (Daicel Celloxide 3000), diglycidyl ester hexahydrophthalicun For example, hydride (Ciba-Geigy CY184) You can.

Preferably the aliphatic epoxy is neopentyl glycol diglycidyl ether and 2-ethylhexyl glycidyl ether, 1,4-butanediol diglycidyl ether, alicyclic epoxy is (3 ', 4'-epoxycyclo Hexane) methyl 3,4-epoxy cyclohexyl carboxylate is preferred.

The photo-curable adhesive according to the present invention may further include a photo-radical polymerizable compound within a range not detrimental to the object of the present invention.

Examples of the photo-radical polymerizable compound include 1 to 6 functional monomers, specifically methyl (meth) acrylate, allyl methacrylate, 2-ethoxyethyl (meth) acrylate, and isodecyl (meth) acrylate , 2-dodecylthioethyl methacrylate, octyl acrylate, 2-methoxyethyl acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, Isooctyl (meth) acrylate, isodexyl (meth) acrylate, stearyl (meth) acrylate, glycidyl methacrylate, tetraperfuryl (meth) acrylate, phenoxyethyl (meth) acrylate, urethane Monofunctional monomers such as acrylate, aminoethyl (meth) acrylate, and dimethylaminoethyl (meth) acrylate; 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, ethylene glycol di (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, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylate, ethylene oxide-modified di (meth) acrylate, bis (2) -Hydroxyethyl) isocyanurate di (meth) acrylate, di (acryloxyethyl) isocyanurate, allylated cyclohexyldi (meth) acrylate, dimethyloldicyclopentane diacrylate , 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 tree (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, and ditrimethylolpropanetetra (meth) acrylate; Pentafunctional monomers such as propionic acid-modified dipentaerythritol penta (meth) acrylate; And 6-functional monomers such as caprolactone-modified dipentaerythritol hexa (meth) acrylate, and 1 to 3 functional monomers are preferable. These may be used alone or in combination of two or more.

The photo-radical polymerizable compound may be included in a content within a range not detrimental to the object of the present invention, for example, may be included in a weight of 30% by weight or less of the total weight of the polymerizable compound. If the content is more than 30% by weight, the moisture and heat resistance may be slightly lowered.

The photopolymerization initiator is for improving the efficiency of the curing reaction, and a photocationic polymerization initiator can be used.

As the photocationic polymerization initiator, for example, onium salt and / or organometallic salt may be used, but is not limited thereto. For example, diaryl iodonium salt, triarylsulfonium salt, aryldiazonium salt, iron-arylene complex, etc. can be used. These may be used alone or in combination of two or more.

Examples of commercially available photo cationic polymerization initiators that can be used are Oputoma-SP-151, Oputoma-SP-170, Oputoma-SP-171 (Asahi Telephone Co., Ltd.), Igacure-261 (Shiba Corporation), Seaside SI -60L, UVI-6990 (Union Calbide), BBI-1C3, MPI-103, TPS-103, DTS-103, NAT-103, NDS-103 (Midori Chemical Company), CPI-110A (San Epro) However, it is not limited thereto. These may be used alone or in combination of two or more.

The content of the photopolymerization initiator is not particularly limited, and for example, it may be included in 0.5 to 10 parts by weight based on 100 parts by weight of the photopolymerizable compound. When the content is within the above range, it has an appropriate curing rate and has excellent durability.

The thickness of the adhesive layer is usually about 0.01 to 10 μm, preferably 0.5 to 5 μm.

In addition, the present invention provides an image display device including the polarizing plate.

The polarizing plate of the present invention is applicable not only to a normal liquid crystal display device, but also to various image display devices such as an electroluminescent display device, a plasma display device, and a field emission display device.

In one embodiment of the image display device of the present invention, the image display device of the present invention is provided with the polarizing plate on the viewer side, and the protective glass of the polarizing plate can be used as a cover glass.

In such a case, since the use of a separate cover glass and OCA, OCR, etc. for attachment thereof is not required, the image display device can be made thinner and lighter.

Hereinafter, preferred embodiments are provided to help the understanding of the present invention, but these examples are merely illustrative of the present invention and do not limit the scope of the appended claims, and the embodiments are within the scope and technical scope of the present invention. It is apparent to those skilled in the art that various changes and modifications to the present invention are possible, and it is natural that such modifications and modifications belong to the appended claims.

Manufacturing example  One. Polarizer  Produce

A transparent unstretched polyvinyl alcohol film (PE60, KURARAY) with a saponification degree of 99.9% or more is swelled by immersing in water (deionized water) at 25 ° C for 1 minute and 20 seconds, followed by swelling of 1.25 mM / L of iodine and 1.25% of potassium iodide , 3% by weight of boric acid was immersed in a 30 ℃ aqueous solution for dyeing for 2 minutes 30 seconds to dye. At this time, in the swelling and dyeing step, stretching was performed at a stretching ratio of 1.56 times and 1.64 times, respectively, and the stretching ratio to the dyeing tank was stretched to be 2.56 times. Subsequently, the mixture was immersed in a crosslinking aqueous solution at 59 ° C containing 11% by weight of potassium iodide and 2% by weight of boric acid for 26 seconds (first crosslinking step), and stretched at a draw ratio of 1.7 times. Thereafter, the mixture was immersed in an aqueous solution for crosslinking at 59 ° C containing 11% by weight of potassium iodide and 2% by weight of boric acid for 20 seconds (second crosslinking step), and stretched at a stretching ratio of 1.34 times. Subsequently, it was stretched 1.01 times while immersing for 10 seconds in a 50 占 폚 complementary color aqueous solution containing 4% by weight of potassium iodide and 1.5% by weight of boric acid.

At this time, the total cumulative draw ratio of swelling, dyeing and crosslinking, and complementary colors was set to 6 times. After the crosslinking was completed, the polyvinyl alcohol film was dried in an oven at 80 ° C for 1 minute, in an oven at 90 ° C for 2 minutes, and in an oven at 100 ° C for 30 seconds to prepare a low shrinking polarizer.

The shrinkage force of the prepared polarizer was 2.5 N / 2 mm.

Manufacturing example  2. Polarizer  Produce

A polyvinyl alcohol film of 75 µm thickness with an average polymerization degree of 2,400 and a saponification degree of 99.9 mol% or more was uniaxially stretched about 5 times by dry, and immersed in 60 ° C water (distilled water) for 1 minute while maintaining the stretched state. After immersion in an aqueous solution at 28 ° C. with a weight ratio of iodine / potassium iodide / distilled water of 0.05 / 5/100 for 60 seconds. Thereafter, the weight ratio of potassium iodide / boric acid / distilled water was immersed in a 72 ° C aqueous solution of 8.5 / 8.5 / 100 for 300 seconds, washed with 26 ° C distilled water for 20 seconds, and then dried at 65 ° C for 10 minutes to produce a PVA-based film. A polarizer in which iodine was adsorbed and oriented was prepared. At this time, the water contact angle of the polarizer surface is 56 °.

The prepared polarizer had a shrinkage of 4.3 N / 2 mm.

Example  And Comparative example

The adhesive composition was prepared, coated on a protective glass with a thickness of 3 µm for the photocurable adhesive composition and 0.1 µm for the water-based adhesive composition, and then the polarizer of the above-mentioned preparation example was attached.

When attaching with a photo-curable adhesive composition, ultraviolet rays were irradiated with a UVA-based accumulated light amount of 300 mJ / cm ² with a UV irradiation device (Fusion H Fusion Valve) after bonding of the polarizer, and when attached with a water-based adhesive composition, a hot air dryer at 80 ° C It was dried for 5 minutes in to prepare a polarizing plate.

As a protective glass, G-leaf protective glass manufactured by Japan Electric Devices Co., Ltd. was used, the polarizer used, the elastic modulus at 80 ° C of the adhesive composition, the thickness and elasticity ratio of the protective glass, and the composition and content of the adhesive composition are shown in Table 1 below. The moisture permeability of the protective glass was equal to 1 * 10 ^-3 (g / m ² day) or less.

division Polarizer Photocurable adhesive composition Water-based adhesive composition Protective glass Photopolymerizable compound Photoinitiator 80 ℃ elastic modulus
(MPa) Z-200
(Solid content) Sodium glyoxylate (solid content) Thickness (㎛) Elasticity ratio
(Gpa / (gcm ^-3 )) ingredient Parts by weight ingredient Parts by weight Parts by weight Parts by weight Example 1 Preparation Example 1 A / B 50/50 G 5 600 - - 35 20 Example 2 Preparation Example 1 A / B 25/75 G 5 900 - - 35 20 Example 3 Preparation Example 1 C / B 25/75 G 5 1200 - - 35 20 Example 4 Preparation Example 1 D / B 25/75 G 5 1100 - - 35 20 Example 5 Preparation Example 1 D / B 25/75 G 5 1100 - - 50 50 Example 6 Preparation Example 1 D / B 25/75 G 5 1100 - - 100 90 Example 7 Preparation Example 1 B / E 75/25 G / H 3/2 900 - - 50 50 Example 8 Preparation Example 2 A / B 50/50 G 5 600 - - 35 20 Example 9 Preparation Example 1 C / B 25/75 G 5 1200 - - 30 10 Example 10 Preparation Example 1 A / B 50/50 G 5 600 - - 100 100 Example 11 Preparation Example 1 A / B 80/20 H 5 450 - - 35 20 Example 12 Preparation Example 1 B 100 - 8 2050 - - 35 20 Comparative Example 1 Preparation Example 1 - - - - - 3 0.3 50 50 Comparative Example 2 Preparation Example 1 A / B 50/50 G 5 600 - - 25 10 Comparative Example 3 Preparation Example 1 A / B 25/75 G 5 900 - - 30 7 Comparative Example 4 Preparation Example 1 E / F 25/75 H 5 100 - - 50 50 A: 1,4-butanediol diglycidyl ether (Aldrich)
B: 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (Daicel)
C: Neopentyl glycol diglycidyl ether (Aldrich)
D: 2-ethylhexyl glycidyl ether (Aldrich)
E: 4-hydroxybutalacrylate (TCI)
F: Dimethylaminoethyl acrylate (TCI)
G: CPI-110A (San-Epro)
H: Irg 184 (Shivasa)
Z-200: Polyvinyl alcohol powder (Japan Synthetic Chemical Co., Ltd., average polymerization degree 1100, average saponification degree 99.5 mol%)

Experimental example

1. Adhesiveness (Cutter evaluation)

After leaving the polarizing plates of Examples and Comparative Examples at room temperature for 1 hour, the blade of the cutter was put between the adhesive layer of the polarizing plate and the film (or protective glass), and the method of entering the blade when the blade was pushed forward was used as the following standard. Was evaluated.

◎: The cutter blade does not fit into any film.

(Circle): When the blade edge of a cutter enters about 2 mm between films, it stops.

(Triangle | delta): When pushing a blade and advancing, it stops when the blade enters 4-5 mm between at least either film.

×: When the blade was pushed forward, the blade was smoothly inserted between at least one film (if the blade was smoothly inserted between either film, the blade would not enter the other side, or 4-5) mm also stops when it enters).

2. Moist heat (85 ℃, 85% RH ) After 120 hours Peeling force

After bonding the polarizing plate prepared in Examples and Comparative Examples using a hand roller on a soda glass using an adhesive, put it into a moisture-resistant heat (85 ° C, 85% RH) oven, take it out after 120 hours, and take it out after 180 hours. Measurement speed 300mm / min) was measured.

3. Moist heat  durability Optical characteristics  change

After the bonding of the polarizing plate prepared in Examples and Comparative Examples using a hand roller on a soda glass using an adhesive, the spectral transmittance τ (λ) before and after leaving for 24 hours at 85 ° C. and 85% was measured using a spectrophotometer (V7100, Japan). Spectroscopy) to confirm changes in transmittance and polarization.

[Equation 2]

Percent change in transmittance (%) = ((Transmittance after moisture heat-Transmittance before moisture heat) / Transmittance before moisture heat) x 100

[Equation 3]

Rate of change of polarization degree (%) = ((Polarity after moisture heat-Polarization before moisture heat) / Polarization before moisture heat) x 100

4. Flexibility  evaluation

When the polarizing plates (100 mm x 100 mm) prepared in Examples and Comparative Examples were bent to have a bending radius of 70 cm, it was confirmed whether cracks in the polarizing plates were generated.

Crack generation: NG, No crack generation: OK

5. Heat resistance evaluation

After bonding the polarizing plates prepared in Examples and Comparative Examples using a hand roller on a soda glass using an adhesive, it was confirmed whether cracks occurred before and after standing at 85 ° C. for 500 hours.

Crack generation: NG, No crack generation: OK

6. Heat shock resistance  evaluation

After bonding the polarizing plate prepared in Examples and Comparative Examples using a hand roller on a soda glass using an adhesive, the thermal shock oven (the temperature was changed from -40 ° C to 85 ° C alternately every 30 minutes, 100 cycles, 6 hours 1 It was checked whether or not cracks were generated before and after the injection by inserting the polarizing plate into the cycle).

Crack generation: NG, No crack generation: OK

division Adhesiveness Peeling power (N) after 120 hours of heat and humidity Change in transmittance after 24 hours of heat and humidity (%) Polarization change after 24 hours of heat and humidity (%) Flexibility Heat resistance Heat shock resistance Example 1 ◎ 2.3 0.2 0.004 OK OK OK Example 2 ◎ 2.6 0.1 0.003 OK OK OK Example 3 ◎ 3.3 0.1 0.002 OK OK OK Example 4 ◎ 3.2 0.1 0.002 OK OK OK Example 5 ◎ 4.1 0.05 0.002 OK OK OK Example 6 ◎ 4.5 0.03 0.001 OK OK OK Example 7 ◎ 1.1 0.3 0.1 OK OK OK Example 8 ◎ 2.2 0.3 0.005 OK OK NG Example 9 ◎ 3.1 0.1 0.001 OK OK OK Example 10 ◎ 2.2 0.3 0.005 OK OK OK Example 11 ○ 1.2 0.4 0.08 OK OK NG Example 12 ○ 0.8 0.2 0.05 OK OK OK Comparative Example 1 △ 0.05 Poor color polarizer defect occurs (transparent) NG NG NG Comparative Example 2 ◎ 2.4 0.2 0.006 NG OK OK Comparative Example 3 ◎ 2.6 0.1 0.004 NG OK OK Comparative Example 4 ○ 0.3 0.8 0.9 NG NG NG

Referring to Table 2, it can be seen that the excellent water resistance and flexibility of Examples 1 to 12 are shown.

However, it can be confirmed that the polarizing plates of Comparative Examples 1 to 4 had significantly lower water resistance or lower flexibility.

Claims (10)

Polarizer; And
A polarizing plate comprising a protective glass having a thickness of 30 to 100 µm and an elasticity ratio of 10 to 100 Gpa / (gcm ^-3 ) attached directly using a photo-curable adhesive containing a photo-cationic polymerizable compound on at least one surface of the polarizer .
The method according to claim 1, wherein the polarizer is a shrinking force of 3 N / 2mm or less, the polarizing plate.
The method according to claim 1, The protective glass has a moisture permeability of 1g / m ² day or less, polarizing plate.
The polarizing plate of claim 1, wherein the photo-cationic polymerizable compound includes at least one of an aliphatic epoxy compound and an alicyclic epoxy compound.
The method according to claim 4, wherein the photo-cationic polymerizable compound is neopentyl glycol diglycidyl ether, 2-ethylhexyl glycidyl ether, 1,4-butanediol diglycidyl ether and (3 ', 4'- Epoxycyclohexane) methyl 3,4-epoxy cyclohexyl carboxylate One or more selected from the group consisting of, polarizing plate.
The polarizing plate of claim 1, wherein the photo-curable adhesive further comprises a photo-radical polymerizable compound.
The polarizing plate according to claim 6, wherein the photo-radical polymerizable compound is 30% by weight or less of the total weight of the polymerizable compound.
The method according to claim 1, wherein the photocurable adhesive is 80 ℃ elastic modulus is 500Mpa to 2000 Mpa, a polarizing plate.
An image display device comprising the polarizing plate of any one of claims 1 to 8.
The image display device according to claim 9, wherein the polarizing plate is provided on the viewer side, and the protective glass of the polarizing plate is used as a cover glass.