Adhesive composition for polarizing plate, polarizing plate, and optical display device

Abstract

Provided are an adhesive composition for a polarizing plate, a polarizing plate, and an optical display device, the adhesive composition including a curable compound and a photoinitiator, in which the curable compound includes (A) an epoxy-based compound and (B) a (meth) acrylate-based compound, the epoxy compound comprises a mixture of a phenolic epoxy compound and an aliphatic epoxy compound, and the (methyl) acrylate compound comprises a mixture of a hydrophilic (methyl) acrylate compound, a hydrophobic (methyl) acrylate compound and a vinyl-containing (methyl) acrylate compound. And 10 to 40 parts by weight of a vinyl group-containing (meth) acrylate-based compound is contained in an amount of 100 parts by weight of the curable compound.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority and benefit of Korean Patent Application No. 10 - 2023 - 0186859, filed on December 20, 2023, the entire disclosure of which is incorporated herein by reference. Technical field

[0003] The present invention relates to an adhesive composition for a polarizing plate, a polarizing plate, and an optical display device. Background art

[0004] A polarizing plate is provided with a polarizer and polarizer protective films on both sides of the polarizer. The polarizer protective film may be a transparent protective film (e.g., triacetylcellulose (TAC), polyethylene terephthalate (PET), acryl, polycarbonate, and cyclic olefin polymer (COP)), or a curable resin protective layer (e.g., epoxy resin or acrylate). The TAC film, as a high moisture - permeable protective film, can be easily adhered using a water - based adhesive because it can permeate moisture. However, the TAC film has limitations in improving the reliability of the polarizing plate. For polarizer protective films other than the TAC film, moisture in the adhesive in the polarizer protective film may not be dried, and a non - solvent - type photocurable adhesive needs to be used.

[0005] Generally, PET, COP, or acrylic films are low moisture - permeable protective films, and a photocurable adhesive needs to be used for the films. Among them, COP - type films (Konica, Japan) manufactured by solution casting and high stretching are preferably used as polarizer protective films because they provide an effect of increasing the curable force of the photocurable adhesive by improving light transmittance, but COP - type films are films that are difficult to adhere using conventional photocurable adhesives.

[0006] The background art of the present invention is described in Japanese Patent Publication No. 2014 - 032270. Summary of the invention

[0007] The present invention aims to provide an adhesive composition for a polarizing plate, which provides an adhesive layer having excellent adhesiveness between a polarizer and a polarizer protective film.

[0008] The present invention also aims to provide an adhesive composition for a polarizing plate, which provides an adhesive layer having excellent reliability by preventing the polarizer from discoloring after being subjected to high - temperature and high - humidity conditions.

[0009] The present invention also aims to provide an adhesive composition for a polarizing plate, which has excellent optical transparency and no haze in its original state.

[0010] One aspect of the present invention provides an adhesive composition for a polarizing plate.

[0011] The adhesive composition for a polarizing plate includes a curable compound and a photoinitiator. The curable compound includes an epoxy compound and a (meth)acrylate compound. The epoxy compound includes a mixture of a novolac epoxy compound and an aliphatic epoxy compound. The (meth)acrylate compound includes a mixture of a hydrophilic (meth)acrylate compound, a hydrophobic (meth)acrylate compound, and a vinyl-containing (meth)acrylate compound. And based on 100 parts by weight of the curable compound, the vinyl-containing (meth)acrylate compound is included in an amount of 10 to 40 parts by weight.

[0012] Another aspect of the present invention provides a polarizing plate.

[0013] The polarizing plate includes a polarizer and a protective film laminated on the lower surface of the polarizer. The polarizer and the protective film are laminated through an adhesive layer, and the adhesive layer contains a cured product of the adhesive composition.

[0014] Still another aspect of the present invention provides an optical display device.

[0015] The optical display device includes the polarizing plate of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a cross-sectional view of a polarizing plate according to an embodiment of the present invention.

[0017] Figure 2 is a schematic diagram showing a schematic illustration for evaluating the decolorization (iodine loss) of a polarizer. DETAILED DESCRIPTION

[0018] With reference to the accompanying drawings, embodiments will be described in detail so that those skilled in the art can easily implement the present invention. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. To clearly illustrate the present invention in the drawings, parts irrelevant to the description are omitted, and throughout the specification, the same or similar components are given the same reference numerals. The lengths, thicknesses, or similar elements of each component shown in the drawings are used to illustrate the present invention, and the present invention is not limited to the lengths, thicknesses, or similar elements shown in the drawings.

[0019] The terms used in this document are for the purpose of describing exemplary embodiments only and are not intended to limit the present invention. Unless otherwise clearly specified in the context, singular expressions include plural expressions.

[0020] In this specification, "upper" and "lower" are based on the drawings and are not necessarily fixed as the upper part and the lower part, and "upper" can be changed to "lower" depending on the viewing angle and "lower" can be changed to "upper" depending on the viewing angle.

[0021] The adhesive composition for a polarizing plate is used to bond a polarizing film and a polarizing film protective film.

[0022] The adhesive composition for a polarizing plate forms an adhesive layer that exhibits excellent adhesiveness between the polarizing film and the polarizing film protective film and prevents the polarizing film from discoloring after being placed under high temperature and high humidity conditions for a long time. Specifically, the adhesive composition for a polarizing plate provides an adhesive layer that not only shows excellent adhesiveness between the polarizing film and common types of polarizing film protective films (e.g., triacetyl cellulose (TAC), polyethylene terephthalate (PET), polycarbonate (PC), cycloolefin polymer (COP), and acrylic film), but also exhibits excellent adhesiveness between the polarizing film and COP-based films produced by solution casting and high stretching, and the adhesive layer shows excellent reliability by preventing the polarizing film from discoloring after being placed under high temperature and high humidity conditions for a long time. The adhesive composition for a polarizing plate provides an optically transparent adhesive layer when photocured because the adhesive composition exhibits excellent optical transparency and no haze in its original state.

[0023] The adhesive composition for a polarizing plate includes a curable compound and a photoinitiator, wherein the curable compound includes an epoxy compound and a (meth)acrylate compound, the epoxy compound includes a mixture of a novolac epoxy compound and an aliphatic epoxy compound, the (meth)acrylate compound includes a mixture of a hydrophilic (meth)acrylate compound, a hydrophobic (meth)acrylate compound, and a vinyl-containing (meth)acrylate compound, and the vinyl-containing (meth)acrylate compound is included in an amount of 10 to 40 parts by weight based on 100 parts by weight of the curable compound.

[0024] In the present invention, among the epoxy compounds used in conventional adhesive compositions for polarizing plates, a mixture of a novolac epoxy compound and an aliphatic epoxy compound is used instead of a bifunctional alicyclic epoxy compound, and a mixture of a hydrophilic (meth)acrylate compound, a hydrophobic (meth)acrylate compound, and a vinyl-containing (meth)acrylate compound is used as the (meth)acrylate compound, wherein the vinyl-containing (meth)acrylate compound is included in an amount of 10 parts by weight to 40 parts by weight based on 100 parts by weight of the curable compound. Thereby, the present invention provides an adhesive layer that not only increases the adhesiveness between a polarizing plate and a common type of polarizing plate protective film, but also increases the adhesiveness between the polarizing plate and a COP type film manufactured by solution casting and high stretching, improves reliability by preventing the polarizing plate from discoloring after being subjected to high temperature and high humidity conditions, and is optically transparent by improving compatibility.

[0025] In one embodiment, based on the solid content in the adhesive composition for a polarizing plate, the curable compound is included in an amount of 90% by weight or more than 90% by weight, such as 90% by weight, 91% by weight, 92% by weight, 93% by weight, 94% by weight, 95% by weight, 96% by weight, 97% by weight, 98% by weight, 99% by weight, and 100% by weight, preferably 95% by weight to 100% by weight.

[0026] In one embodiment, based on 100 parts by weight of the curable compound, the total amount of the epoxy compound and the (meth)acrylate compound may be 95 parts by weight or more than 95 parts by weight, such as 95 parts by weight, 96 parts by weight, 97 parts by weight, 98 parts by weight, 99 parts by weight, and 100 parts by weight, preferably 99 parts by weight to 100 parts by weight, more preferably 100 parts by weight. Within the above range, the effects of improving adhesiveness, reliability, and compatibility can be excellent.

[0027] The curable compound may be a photocurable compound.

[0028] Epoxy compound

[0029] Based on 100 parts by weight of the curable compound, the epoxy compound may be included in an amount of 30 parts by weight to 70 parts by weight. Within the above range, there may be no problem of insufficient peel force due to the lack of (meth)acrylate compounds for penetrating into the polarizing plate protective film, and there may be no problem of a decrease in the overall glass transition temperature of the adhesive layer and insufficient bonding force with the polarizing plate resulting in discoloration under high temperature and high humidity conditions. Preferably, the epoxy compound may be included in an amount of 40 parts by weight to 60 parts by weight.

[0030] The epoxy compound includes a mixture of a novolac epoxy compound and an aliphatic epoxy compound.

[0031] In one embodiment, based on 100 parts by weight of the epoxy compound, the total amount of the phenolic epoxy compound and the aliphatic epoxy compound may be 95 parts by weight or more than 95 parts by weight, such as 95 parts by weight, 96 parts by weight, 97 parts by weight, 98 parts by weight, 99 parts by weight, and 100 parts by weight, preferably 99 parts by weight to 100 parts by weight, and more preferably 100 parts by weight. Within the above range, the effects of the present invention can be easily implemented.

[0032] The phenolic epoxy compound may have a high glass transition temperature, and thus may be beneficial to improving the reliability of the polarizing plate. Compared with the bifunctional alicyclic epoxy compound commonly used in the adhesive composition, the phenolic epoxy compound may have a relatively slow reaction rate, and thus may provide relatively high peel force performance.

[0033] The phenolic epoxy compound may be a bifunctional epoxy compound or a more functional epoxy compound, and may include, for example, a compound represented by the following Chemical Formula 1:

[0034] [Chemical Formula 1]

[0035]

[0036] (In Chemical Formula 1,

[0037] R1, R2, and R3 are each hydrogen or a C1 to C 10 alkyl group;

[0038] R4, R5, and R6 are each independently a C1 to C 10 alkyl group;

[0039] m1 and m3 are each independently an integer from 0 to 3;

[0040] m2 is an integer from 0 to 2; and

[0041] n is an integer from 1 to 1000).

[0042] For example, the phenolic epoxy compound may include one or more of cresol novolac epoxy compounds including O-cresol novolac epoxy resin and phenol novolac epoxy compounds.

[0043] Based on 100 parts by weight of the curable compound, the phenolic epoxy compound can be included in an amount of 10 to 40 parts by weight, such as 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, 20 parts by weight, 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight, 30 parts by weight, 31 parts by weight, 32 parts by weight, 33 parts by weight, 34 parts by weight, 35 parts by weight, 36 parts by weight, 37 parts by weight, 38 parts by weight, 39 parts by weight, and 40 parts by weight, preferably 15 to 30 parts by weight. Within the above range, the problem of haze may not occur in the adhesive composition, and the problem of reducing the peel strength can be solved by preventing other components of the adhesive composition from penetrating into the adherend.

[0044] Based on 100 parts by weight of the epoxy compound, the phenolic epoxy compound can be included in an amount of 20 to 60 parts by weight, such as 20 parts by weight, 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight, 30 parts by weight, 31 parts by weight, 32 parts by weight, 33 parts by weight, 34 parts by weight, 35 parts by weight, 36 parts by weight, 37 parts by weight, 38 parts by weight, 39 parts by weight, 40 parts by weight, 41 parts by weight, 42 parts by weight, 43 parts by weight, 44 parts by weight, 45 parts by weight, 46 parts by weight, 47 parts by weight, 48 parts by weight, 49 parts by weight, 50 parts by weight, 51 parts by weight, 52 parts by weight, 53 parts by weight, 54 parts by weight, 55 parts by weight, 56 parts by weight, 57 parts by weight, 58 parts by weight, 59 parts by weight, and 60 parts by weight, preferably 40 to 60 parts by weight. Within the above range, the adhesiveness, reliability, and compatibility can be easily improved.

[0045] The aliphatic epoxy compound has the following characteristics: It has a long induction period due to the stability brought by the epoxy ring being cationically protonated and then forming a hydrogen bond with the adjacent oxygen atom. The aliphatic epoxy compound undergoes a post-reaction after a long induction period. This can provide effects such as increasing the peel strength and improving the reliability under high-temperature and high-humidity conditions.

[0046] Due to the property that protons in epoxy compounds are captured during cationic polymerization, aliphatic epoxy compounds cause a delay in the growth reaction of epoxy compounds. In the present invention, based on the growth delay effect of aliphatic epoxy compounds, in order to enable a COP-based film (which is a non-adhesive polarizer protective film) manufactured by solution casting and high stretching to be cured together with a hydrophobic difunctional (meth)acrylate (which will be described later), before the fluidity of the hydrophobic difunctional (meth)acrylate disappears, sufficient time is provided to allow the hydrophobic difunctional (meth)acrylate to penetrate into the COP-based film, and then post-curing is carried out to provide good adhesiveness and reliability.

[0047] In one embodiment, based on 100 parts by weight of the aliphatic epoxy compound, the hydrophobic (meth)acrylate compound may be included in an amount of 50 to 200 parts by weight, such as 50 parts by weight, 55 parts by weight, 60 parts by weight, 65 parts by weight, 70 parts by weight, 75 parts by weight, 80 parts by weight, 85 parts by weight, 90 parts by weight, 95 parts by weight, 100 parts by weight, 105 parts by weight, 110 parts by weight, 115 parts by weight, 120 parts by weight, 125 parts by weight, 130 parts by weight, 135 parts by weight, 140 parts by weight, 145 parts by weight, 150 parts by weight, 155 parts by weight, 160 parts by weight, 165 parts by weight, 170 parts by weight, 175 parts by weight, 180 parts by weight, 185 parts by weight, 190 parts by weight, 195 parts by weight, and 200 parts by weight, preferably 50 to 100 parts by weight. Within the above range, due to the interaction between the above aliphatic epoxy compound and the hydrophobic (meth)acrylate compound, the adhesiveness to the COP-based film manufactured by solution casting and high stretching can be excellent.

[0048] In addition, the aliphatic epoxy compound can improve the optical transparency of the adhesive composition for a polarizer, which contains the following phenolic epoxy compound and (meth)acrylate compound, thereby improving the compatibility of the adhesive composition. In one embodiment, the adhesive composition may have a haze of 1% or less, such as 0% to 1% (for example, measured in the visible light region).

[0049] The aliphatic epoxy compounds may include one or more of the following: monoglycidyl ether compounds having a straight-chain alkyl chain containing four or more carbon atoms, diglycidyl ether compounds having a straight-chain alkylene chain containing four or more carbon atoms, and diglycidyl ether compounds having 2 moles or more than 2 moles of ethylene oxide or propylene oxide in their molecules. These aliphatic epoxy compounds can easily provide the effects of the present invention in the adhesive composition of the present invention. The "2 moles or more than 2 moles" means that 1 mole of molecule contains 2 moles or more than 2 moles of ethylene oxide or propylene oxide, for example, -(ethylene oxide or propylene oxide) n - (wherein, n is 2 or more than 2).

[0050] The monoglycidyl ether compounds having a straight-chain alkyl chain containing four or more carbon atoms may have a straight-chain or branched-chain alkyl chain containing four or more carbon atoms, preferably four to ten carbon atoms, and more preferably four to six carbon atoms. For example, the monoglycidyl ether compounds may be butyl monoglycidyl ether including n-butyl monoglycidyl ether and 2-ethylhexyl monoglycidyl ether.

[0051] The diglycidyl ether compounds having a straight-chain alkylene chain containing four or more carbon atoms can easily provide the effects of the present invention because the straight-chain alkylene chain containing four or more carbon atoms provides a reaction delay effect.

[0052] The diglycidyl ether compounds having a straight-chain alkylene chain containing four or more carbon atoms may have a straight-chain or branched-chain alkylene chain containing four or more carbon atoms, preferably four to ten carbon atoms, more preferably four to six carbon atoms. For example, the diglycidyl ether compounds may be one or more of 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, and neopentyl glycol diglycidyl ether. Preferably, the diglycidyl ether compounds may be one or more of unsubstituted diglycidyl ether compounds having four to six carbon atoms (such as 1,4-butanediol diglycidyl ether and 1,6-hexanediol diglycidyl ether).

[0053] The diglycidyl ether compounds having 2 moles or more than 2 moles of ethylene oxide or propylene oxide in their molecules can easily provide the effects of the present invention because 2 moles or more than 2 moles of ethylene oxide or propylene oxide in the molecule provides a reaction delay effect. The "2 moles or more than 2 moles" means that 1 mole of molecule contains 2 moles or more than 2 moles of ethylene oxide or propylene oxide, for example, -(ethylene oxide or propylene oxide) n - (wherein, n is 2 or more than 2).

[0054] The diglycidyl ether compounds having 2 moles or more than 2 moles of ethylene oxide or propylene oxide in their molecules may preferably be diglycidyl ether compounds having 2 to 10 moles of ethylene oxide or propylene oxide in their molecules. For example, the diglycidyl ether compounds may be one or more of polyethylene glycol diglycidyl ether and polypropylene glycol diglycidyl ether.

[0055] Preferably, the aliphatic epoxy compounds may include one or more of the following: monoglycidyl ether compounds having a straight-chain alkyl chain containing four or more carbon atoms, and diglycidyl ether compounds having a straight-chain alkylene chain containing four or more carbon atoms. In such a case, the adhesiveness, reliability, and compatibility of the present invention can be further improved.

[0056] Based on 100 parts by weight of the curable compound, the aliphatic epoxy compounds may be included in an amount of 10 to 40 parts by weight, preferably 15 to 30 parts by weight. Within the above range, the above effects of the present invention can be provided, the peel strength can be increased by ensuring the initial reaction rate, and there can be no problem of reducing the reliability of the polarizing plate due to a low glass transition temperature.

[0057] Based on 100 parts by weight of the epoxy compounds, the aliphatic epoxy compounds may be included in an amount of 40 to 80 parts by weight, such as 40 parts by weight, 41 parts by weight, 42 parts by weight, 43 parts by weight, 44 parts by weight, 45 parts by weight, 46 parts by weight, 47 parts by weight, 48 parts by weight, 49 parts by weight, 50 parts by weight, 51 parts by weight, 52 parts by weight, 53 parts by weight, 54 parts by weight, 55 parts by weight, 56 parts by weight, 57 parts by weight, 58 parts by weight, 59 parts by weight, 60 parts by weight, 61 parts by weight, 62 parts by weight, 63 parts by weight, 64 parts by weight, 65 parts by weight, 66 parts by weight, 67 parts by weight, 68 parts by weight, 69 parts by weight, 70 parts by weight, 71 parts by weight, 72 parts by weight, 73 parts by weight, 74 parts by weight, 75 parts by weight, 76 parts by weight, 77 parts by weight, 78 parts by weight, 79 parts by weight, and 80 parts by weight, preferably 40 to 60 parts by weight. Within the above range, the adhesiveness, reliability, and compatibility can be easily improved.

[0058] In one embodiment, based on 100 parts by weight of the epoxy compounds, one or more of the alicyclic epoxy compounds and the hydrogenated aromatic epoxy compounds may be included in an amount of 5 parts by weight or less than 5 parts by weight, preferably 0 to 5 parts by weight, or 0 parts by weight.

[0059] (Meth)acrylate compounds

[0060] Based on 100 parts by weight of the curable compound, the (meth)acrylate compound can be included in an amount of 30 to 70 parts by weight. Within the above range, the adhesiveness, reliability, and compatibility can be easily improved. Preferably, the (meth)acrylate compound can be included in an amount of 40 to 60 parts by weight.

[0061] The (meth)acrylate compound includes a mixture of a hydrophilic (meth)acrylate compound, a hydrophobic (meth)acrylate compound, and a vinyl-containing (meth)acrylate compound.

[0062] In one embodiment, based on 100 parts by weight of the (meth)acrylate compound, the total amount of the vinyl-containing (meth)acrylate compound, the hydrophilic (meth)acrylate compound, and the hydrophobic (meth)acrylate compound can be 95 parts by weight or more than 95 parts by weight, such as 95 parts by weight, 96 parts by weight, 97 parts by weight, 98 parts by weight, 99 parts by weight, and 100 parts by weight, preferably 99 to 100 parts by weight, and more preferably 100 parts by weight. Within the above range, the adhesiveness, reliability, and compatibility can be easily improved.

[0063] The hydrophilic (meth)acrylate compound can exhibit favorable properties in the adhesion of a polarizer to a polarizer protective film, especially a hydrophilic substrate (such as a TAC film), and has a high affinity for a primer-treated PET film, thereby providing a favorable adhesion effect.

[0064] In one embodiment, the hydrophilic (meth)acrylate compound can be a difunctional (meth)acrylate compound having two (meth)acrylate groups as difunctional (meth)acrylate and having an epoxyalkyl group between the (meth)acrylate groups. The compound can exhibit favorable adhesion properties to a hydrophilic adherend having a hydroxyl group (such as a polarizer), and also has a high affinity for a primer-treated polyester film, thereby contributing to an increase in adhesiveness. The epoxyalkyl group can be ethylene oxide or propylene oxide.

[0065] The epoxyalkyl group can be included in the above compound in an amount of 1 mole or more than 1 mole, preferably 2 moles or more than 2 moles, and more preferably 2 to 5 moles. The "1 mole or more than 1 mole" means that 1 mole of the above compound contains 1 mole or more than 1 mole of the epoxyalkyl group, such as -(epoxyalkane) n - (where n is 1 or more than 1).

[0066] Within the above range, the effects of the present invention can be easily implemented. For example, the hydrophilic (meth)acrylate compound may be one or more of diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, and tripropylene glycol di(meth)acrylate.

[0067] Based on 100 parts by weight of the curable compound, the hydrophilic (meth)acrylate compound is included in an amount of 5 to 30 parts by weight, such as 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, 20 parts by weight, 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight, and 30 parts by weight, preferably 10 to 25 parts by weight. Within the above range, there may be no problems that the reaction rate becomes too fast and interfacial peeling occurs due to high shrinkage force.

[0068] Based on 100 parts by weight of the (meth)acrylate compound, the hydrophilic (meth)acrylate compound is included in an amount of 10 to 80 parts by weight, such as 10 parts by weight, 15 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight, 45 parts by weight, 50 parts by weight, 55 parts by weight, 60 parts by weight, 65 parts by weight, 70 parts by weight, 75 parts by weight, and 80 parts by weight, preferably 10 to 60 parts by weight, 10 to 50 parts by weight, and 20 to 40 parts by weight. Within the above range, the adhesiveness, reliability, and compatibility can be easily improved.

[0069] The hydrophobic (meth)acrylate compound having low polarity can exhibit excellent penetration characteristics for a low-polarity polarizer protective film, particularly a COP film manufactured by solution casting and high stretching, thereby contributing to an increase in the adhesiveness to the protective film and an increase in the adhesiveness after high-temperature and high-humidity conditions.

[0070] The hydrophobic (meth)acrylate compound may have two (meth)acrylate groups as a bifunctional (meth)acrylate compound. The hydrophobic monofunctional (meth)acrylate compound having one (meth)acrylate group can smoothly penetrate into the polarizer protective film, especially a COP film, but it may not easily exhibit the effect of improving the peel force due to the limited increase in the crosslinking degree.

[0071] The hydrophobic (meth)acrylate compound may have an unsubstituted straight-chain alkylene group having six or more carbon atoms between the (meth)acrylate groups. A straight-chain alkylene group having less than six carbon atoms increases the polarity of the compound, making it difficult to penetrate the polarizing film protective layer, especially a COP film, and thus may not easily exhibit the effect of improving the peeling force.

[0072] The hydrophobic (meth)acrylate compound may not have an ether functional group (epoxyalkyl group), such as ethylene oxide or propylene oxide.

[0073] In one embodiment, the hydrophobic (meth)acrylate compound may have an unsubstituted straight-chain or branched-chain alkylene group having six or more carbon atoms, such as 6 to 15 carbon atoms, and for example, may be one or more of the following: hexanediol di(meth)acrylate, including 1,6-hexanediol di(meth)acrylate; octanediol di(meth)acrylate, including 1,8-octanediol di(meth)acrylate; nonanediol di(meth)acrylate, including 1,9-nonanediol di(meth)acrylate; and decanediol di(meth)acrylate, including 1,10-decanediol di(meth)acrylate. Preferably, the hydrophobic (meth)acrylate compound may be one or more of 1,6-hexanediol di(meth)acrylate and 1,9-nonanediol di(meth)acrylate.

[0074] Based on 100 parts by weight of the curable compound, the hydrophobic (meth)acrylate compound may be included in an amount of 10 to 40 parts by weight, such as 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, 20 parts by weight, 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight, 30 parts by weight, 31 parts by weight, 32 parts by weight, 33 parts by weight, 34 parts by weight, 35 parts by weight, 36 parts by weight, 37 parts by weight, 38 parts by weight, 39 parts by weight, and 40 parts by weight, preferably 20 to 30 parts by weight. Within the above range, the adhesiveness to the hydrophobic polarizing film protective layer (such as a COP film) and the adhesiveness to the hydrophilic polarizing film and the hydrophilic polarizing film protective layer can all be improved.

[0075] Based on 100 parts by weight of the (meth)acrylate compound, the hydrophobic (meth)acrylate compound can be included in an amount of 10 to 80 parts by weight, such as 10 parts by weight, 15 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight, 45 parts by weight, 50 parts by weight, 55 parts by weight, 60 parts by weight, 65 parts by weight, 70 parts by weight, 75 parts by weight, and 80 parts by weight, preferably 10 to 60 parts by weight, 10 to 50 parts by weight, and 20 to 40 parts by weight. Within the above range, adhesiveness, reliability, and compatibility can be easily improved.

[0076] The vinyl-containing (meth)acrylate compound has both a (meth)acrylate group and a vinyl group. Therefore, in addition to the physical distortion between the epoxy compound and the (meth)acrylate compound, there is a chemical covalent bond between the epoxy compound and the (meth)acrylate compound, which inhibits the movement between molecules even under high-temperature and high-humidity conditions. Thus, the adhesiveness after high-temperature and high-humidity conditions is improved, and the discoloration of the polarizing plate after high-temperature and high-humidity conditions is inhibited, thereby providing the effect of increasing reliability.

[0077] Based on 100 parts by weight of the curable compound, the vinyl-containing (meth)acrylate compound can be included in an amount of 10 to 40 parts by weight. When the content of the vinyl-containing (meth)acrylate compound is less than 10 parts by weight, the effects of increasing adhesiveness and inhibiting the discoloration of the polarizing plate in the present invention may be reduced. When the content of the vinyl-containing (meth)acrylate compound exceeds 40 parts by weight, the effect of facilitating the interfacial peeling with other components of the adhesive composition may be reduced, and the hydrophobicity of the adhesive composition may increase, thereby weakening the bonding force with the polarizing plate as a hydrophilic substrate.

[0078] The vinyl-containing (meth)acrylate compound has both a (meth)acrylate group and a vinyl group in its molecule. Thus, the (meth)acrylate group is coupled with the hydrophilic (meth)acrylate compound and the hydrophobic (meth)acrylate compound, and the vinyl group is coupled with a mixture of phenolic epoxy compounds and aliphatic epoxy compounds, thereby easily providing the effects of the present invention.

[0079] In one embodiment, the vinyl-containing (meth)acrylate compound can be a monofunctional (meth)acrylate compound and can be a monofunctional vinyl compound. The vinyl-containing (meth)acrylate compound is different from the hydrophilic (meth)acrylate compound and the hydrophobic (meth)acrylate compound.

[0080] In one embodiment, the vinyl-containing (meth)acrylate compound may have an epoxyalkyl group. The epoxyalkyl group may be contained between the (meth)acrylate group and the vinyl in the (meth)acrylate compound to provide an effect of increasing the compatibility with the above-mentioned aliphatic epoxy ether compounds and (meth)acrylate compounds. For example, the epoxyalkyl group may be an epoxyethyl group or an epoxypropyl group, preferably an epoxyethyl group.

[0081] In one embodiment, the vinyl-containing (meth)acrylate compound may be a compound represented by the following Chemical Formula 2:

[0082] [Chemical Formula 2]

[0083]

[0084] (In Chemical Formula 2,

[0085] R is hydrogen or methyl; and

[0086] n is an integer from 1 to 5).

[0087] For example, the vinyl-containing (meth)acrylate compound may be 2-(2-vinyloxyethoxy)ethyl (meth)acrylate or a similar compound.

[0088] Based on the total amount of 100 parts by weight of the (meth)acrylate compound, preferably the total amount of the hydrophilic (meth)acrylate compound, the hydrophobic (meth)acrylate compound, and the vinyl-containing (meth)acrylate compound, the vinyl-containing (meth)acrylate compound may be included in an amount of 10 parts by weight to 80 parts by weight, such as 10 parts by weight, 15 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight, 45 parts by weight, 50 parts by weight, 55 parts by weight, 60 parts by weight, 65 parts by weight, 70 parts by weight, 75 parts by weight, and 80 parts by weight, preferably 10 parts by weight to 60 parts by weight and 20 parts by weight to 60 parts by weight. Within the above range, adhesiveness, reliability, and compatibility can be easily improved.

[0089] The photoinitiator includes a mixture of a photo radical initiator and a photo ion initiator.

[0090] Based on 100 parts by weight of the curable compound, the photoinitiator may be included in an amount of 1 part by weight to 15 parts by weight, preferably 1 part by weight to 10 parts by weight. Within the above range, there may be no problem that the adhesive composition remains uncured, and there may be no problem that the residue of the adhesive composition remaining after overuse reduces the light transmittance of the adhesive layer.

[0091] The photo-radical initiator can be a cyclohexyl phenyl ketone compound, a thioxanthone compound, or a similar compound.

[0092] Based on 100 parts by weight of the curable compound, the photo-radical initiator can be included in an amount of 0.5 to 10 parts by weight, for example, 1 to 6 parts by weight. Within the above range, the adhesive composition can be sufficiently cured, and problems such as a decrease in adhesiveness and bleeding of the photo-radical initiator can be avoided.

[0093] The photo-ion initiator can include a cation (which is an onium ion) and an anion of an onium salt. Specific examples of the onium ion include: diaryliodonium, such as diphenyliodonium, 4-methoxydiphenyliodonium, bis(4-methylphenyl)iodonium, bis(4-tert-butylphenyl)iodonium, bis(dodecylphenyl)iodonium, and (4-methylphenyl)(4-(2-methylpropyl)phenyl)iodonium; triarylsulfonium, such as triphenylsulfonium, diphenyl-4-thiophenoxyphenylsulfonium, and diphenyl-4-(phenylthio)phenylsulfonium; bis[4-(diphenylsulfonium)-phenyl]sulfide; bis[4-(bis(4-(2-hydroxyethyl)phenyl)sulfonium)-phenyl]sulfide; and 5-2,4-(cyclopentadienyl)[1,2,3,4,5,6-η-(methylethyl)-benzene]-iron(1+). Specific examples of the anion include tetrafluoroborate (BF4 - ), hexafluorophosphate (PF6 - ), hexafluoroantimonate (SbF6 - ), hexafluoroarsenate (AsF6 - ), and hexafluoroantimonate (SbCl6 - ).

[0094] Based on 100 parts by weight of the curable compound, the photo-ion initiator can be included in an amount of 0.5 to 10 parts by weight, for example, 1 to 6 parts by weight. Within the above range, the adhesive composition can be sufficiently cured, and problems such as a decrease in adhesiveness and bleeding of the photo-ion initiator can be avoided.

[0095] The adhesive composition can be prepared by mixing the curable compound with the photo-initiator. The adhesive composition can be a solvent-free formulation or can also include a solvent to increase applicability (coating ability).

[0096] The adhesive composition can also include an antioxidant, an ultraviolet absorber, an ion conductor, an additive that imparts conductivity (such as fine particles of a conductive metal oxide, an additive that imparts light diffusibility, a viscosity modifier), or a similar additive to such an extent that the effects of the present invention are not impaired.

[0097] The cured product of the adhesive composition may have a glass transition temperature of 30°C to 150°C, preferably 50°C to 120°C. Within the above range, it can have the effects of preventing layer separation breakage during cutting and improving thermal shock reliability.

[0098] The polarizing plate of the present invention includes an adhesive layer formed from the adhesive composition for a polarizing plate of the present invention. The polarizing plate includes a polarizer and a protective film laminated on one surface of the polarizer, wherein the polarizer and the protective film are laminated together with the adhesive layer, and the adhesive layer contains the cured product of the adhesive composition of the present invention.

[0099] Refer to Figure 1 , the polarizing plate may include: a polarizer 10; an adhesive layer 20 and a lower polarizer protective film 30 sequentially formed on one surface of the polarizer 10; and an upper polarizer protective layer 40 laminated on the other surface of the polarizer 10.

[0100] Polarizer

[0101] The polarizer 10 can polarize external light or internal light.

[0102] The polarizer 10 may include a polyvinyl alcohol-based polarizer, wherein the polyvinyl alcohol-based film is dyed with iodine or the like. For example, the polyvinyl alcohol-based polarizer is manufactured by dyeing a polyvinyl alcohol film with iodine or a dichroic dye and stretching it in a specific direction. Specifically, it is manufactured through a swelling process, a dyeing step, and a stretching step. The methods for implementing each step are well known to those skilled in the art.

[0103] The thickness of the polarizer 10 may be 1 μm to 50 μm. Within the above range, the polarizer can be used in an optical display device.

[0104] Adhesive layer

[0105] The adhesive layer 20 can be directly formed on the polarizer and the lower polarizer protective film to bond the polarizer and the lower polarizer protective film.

[0106] The adhesive layer 20 can be formed from the above composition for the adhesive layer. Specifically, the adhesive layer composition can be coated on one side of the polarizer or the lower polarizer protective film to a predetermined thickness, and then the adhesive layer composition is photocured to form the adhesive layer. Photocuring refers to curing the composition by ultraviolet (UV) irradiation, and it can be implemented by adjusting the light amount and wavelength according to the coating thickness of the adhesive composition.

[0107] The thickness of the adhesive layer 20 may be 0.01 μm to 10 μm, preferably 1 μm to 5 μm. Within the above range, the adhesiveness between the polarizer and the polarizer protective film can be ensured.

[0108] Lower polarizer protective film 30

[0109] The lower polarizer protective film can be laminated on the lower surface of the polarizer (the light incident surface of the internal light of the polarizer) to provide an additional effect for the polarizing plate.

[0110] In one embodiment, as the lower polarizer protective film, a conventional polarizer protective film known to those skilled in the art can be used, such as the polarizer protective film described in the upper polarizer protective layer below.

[0111] In another embodiment, in the present invention, a COP-based film as a non-adhesive protective film manufactured by solution casting and high stretching can be used as the lower polarizer protective film.

[0112] The COP-based film manufactured by solution casting and high stretching is excellent in the sense that when applied to the polarizing plate, it provides an effect of improving the curability of the photocurable adhesive due to an increase in light transmittance.

[0113] Upper polarizer protective layer

[0114] The upper polarizer protective layer 40 can be formed on the upper surface of the polarizer to support the polarizer. The upper polarizer protective layer can include one or more of an optically transparent protective film and a protective coating.

[0115] When the upper polarizer protective layer is of the protective film type, it can include a protective film made of an optically transparent resin. The protective film can be formed by melting and extruding the resin. When necessary, a stretching process can be further added. The resin can include one or more of the following: cellulose ester resins (such as cellulose triacetate), cyclic polyolefin resins (such as cyclic olefin polymer (COP)), polycarbonate resins, polyester resins (such as polyethylene terephthalate (PET)), polyethersulfone resins, polysulfone resins, polyamide resins, polyimide resins, acyclic polyolefin resins, polyacrylate resins (such as polymethyl methacrylate resin), polyvinyl alcohol resins, polyvinyl chloride resins, and polyvinylidene chloride resins. Preferably, the protective film can be a film formed of a cyclic polyolefin resin including a cyclic polyolefin.

[0116] When the upper polarizer protective layer is of the protective coating type, it can improve the good adhesiveness, transparency, mechanical strength, thermal stability, moisture barrier property, and durability to the polarizer. In one embodiment, the protective coating for the protective layer can be formed of a photoactive energy ray curable resin composition containing a photoactive energy ray curable compound and a polymerization initiator.

[0117] The active energy ray-curable compound may include one or more of a cationically polymerizable curable compound, a radically polymerizable curable compound, a urethane resin, and a silicone resin. The cationically polymerizable curable compound may be an epoxy compound having at least one epoxy group in its molecule, or an oxetane compound having at least one oxetane ring in its molecule. The radically polymerizable curable compound may be a (meth)acrylate compound having at least one (meth)acryloyloxy group in its molecule.

[0118] The thickness of the upper polarizer protective layer 40 may be 5 μm to 200 μm, specifically 30 μm to 120 μm, and may be 50 μm to 100 μm for the protective film type and 5 μm to 50 μm for the protective coating type. Within the above range, the upper polarizer protective layer can be used in a light-emitting display device.

[0119] Although not shown in Figure 1 functional coatings such as a hard coat, an anti-fingerprint layer, and an anti-reflection layer may also be formed on the upper surface of the upper polarizer protective layer 40.

[0120] Although Figure 1 not shown in, when the upper polarizer protective layer 40 is of the protective film type, an adhesive layer may be further formed between the protective layer and the polarizer. The adhesive layer may be formed of a common adhesive for a polarizing plate (e.g., an aqueous adhesive, a photocurable adhesive, or a pressure-sensitive adhesive).

[0121] Although not shown in Figure 1 the polarizing plate may also include a polarizer protective film, an anti-reflection film, a retardation film (liquid crystal layer or non-liquid crystal layer), or a similar film commonly used in a polarizing plate.

[0122] An optical display device according to an embodiment of the present invention includes the polarizing plate of the present invention. For example, the optical display device may be a light-emitting device display device or a liquid crystal display device including a light-emitting device.

[0123] Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred examples of the present invention. However, these are presented as preferred examples of the present invention and should not be construed as limiting the present invention in any way.

[0124] Example 1

[0125] (1) Preparation of an adhesive composition for a photocurable polarizing plate

[0126] As epoxy compounds, 25 parts by weight of a phenolic epoxy compound (O-cresol novolac epoxy resin, Kukdo Chemical Co., Ltd.) and 25 parts by weight of an aliphatic epoxy compound (1,4-butanediol diglycidyl ether, Kukdo Chemical Co., Ltd.) were used. As (meth)acrylate compounds, 20 parts by weight of dipropylene glycol diacrylate (Miwon Commercial Co., Ltd.), 20 parts by weight of 1,9-nonanediol diacrylate (Kyoeisha Chemical Co., Ltd.), and 10 parts by weight of 2-(2-vinyloxyethoxy)ethyl acrylate (Nippon Shokubai Co., Ltd.) were used.

[0127] The epoxy compounds and the (meth)acrylate compounds were mixed, and 1 part by weight of a photoinitiator (Irgacure 184, 1-hydroxycyclohexyl phenyl ketone, BASF Corporation) and 6 parts by weight of a photoacid generator (CPI-100P, San-Apro Ltd.) were added to the mixture and mixed to prepare a solvent-free adhesive composition for a photocurable polarizing plate.

[0128] (2) Manufacture of a polarizing plate

[0129] A polyvinyl alcohol film (PS#60, Kuraray, saponification degree: 99.5%, thickness before stretching: 60 μm) was dyed by immersing it in a 0.3% aqueous iodine solution, and the resulting film was subjected to machine direction (MD) stretching to achieve an MD uniaxial draw ratio of 6 times. The stretched polyvinyl alcohol film was immersed in a 3% boric acid and 2% potassium iodide aqueous solution for color correction and dried at 50 °C for 4 minutes to manufacture a polarizing sheet (light transmittance: 45%, thickness: 7 μm).

[0130] A polyethylene terephthalate (PET) film (thickness: 80 μm, transversely uniaxially stretched, Toyobo) was used as an upper polarizing plate protective film, and the surface on which the adhesive composition was to be coated was subjected to a primer treatment. A cyclic olefin polymer (COP) film (manufactured by solution casting and high stretching, thickness: 37 μm, Konica) or a triacetyl cellulose film (Zero TAC, thickness: 40 μm) was used as a lower polarizing plate protective film, and the surface on which the adhesive composition was to be coated was subjected to a corona treatment with 100 doses.

[0131] The prepared photocurable adhesive composition is coated onto the primer-treated surface of the upper polarizing film protective layer to a predetermined thickness, and the prepared photocurable adhesive composition is coated onto the corona-treated surface of the lower polarizing film protective layer to a predetermined thickness. After laminating each of the prepared polarizing films, the adhesive composition is cured by irradiating ultraviolet rays from the lower polarizing film protective layer side with a metal halide lamp under the conditions of 400 mW / cm 2 and 1000 mJ / cm 2 to manufacture a polarizing plate in which an upper polarizing film protective layer, an adhesive layer, a polarizing film, an adhesive layer, and a lower polarizing film protective layer are laminated in sequence. The polarizing plate is manufactured at 22°C to 25°C and a relative humidity of 20% to 60%.

[0132] Examples 2 to 6

[0133] Except that in the preparation of the solvent-free adhesive composition for the photocurable polarizing plate in Example 1, the content and / or type of each component was changed as shown in Table 1 below, the composition and the polarizing plate were manufactured in the same manner as in Example 1. In Table 1 below, "-" indicates that the corresponding component is not included.

[0134] Comparative Examples 1 to 7

[0135] Except that in the preparation of the solvent-free adhesive composition for the photocurable polarizing plate in Example 1, the content and / or type of each component was changed as shown in Table 1 below, the composition and the polarizing plate were manufactured in the same manner as in Example 1.

[0136] As shown in Table 2 below, the physical properties of the polarizing plates manufactured in the examples and comparative examples were evaluated, and the results are shown in Table 2 below.

[0137] (1) Compatibility of the adhesive composition: The adhesive compositions prepared in the examples and comparative examples were visually observed and evaluated based on the following criteria.

[0138] ○: The composition is transparent.

[0139] ×: There is delamination or haze in the composition.

[0140] (2) Adhesiveness: A double-sided foam adhesive tape (VHS, 3M) was attached to the lower polarizing film protective layer side of the polarizing plates manufactured in the examples and comparative examples, and cut into a polarizing film area of 25 mm × 150 mm (MD × TD). After removing the release film of the double-sided foam adhesive tape, the polarizing plate was laminated on the surface of non-alkali glass (thickness: 0.5 t) and allowed to stand at room temperature for 30 minutes to manufacture a specimen.

[0141] In the fabricated specimens, an attempt was made to slightly separate the polarizer from the lower polarizer protective film by inserting a cutter blade obliquely between the polarizer and the lower polarizer protective film. The adhesiveness was evaluated according to the following criteria.

[0142] ○: There was no separation at all between the lower protective film and the polarizer.

[0143] △: There was intermittent separation between the lower protective film and the polarizer.

[0144] ×: The lower protective film and the polarizer were easily separable.

[0145] (3) High temperature and high humidity reliability: The polarizing plates fabricated in the examples and comparative examples were cut into squares with a size of 50 mm × 50 mm, the absorption axis direction of the polarizer was at a 45° angle, and the obtained squares were attached to a glass plate using an acrylic adhesive layer to fabricate specimens. The specimens were placed in a chamber set at 60 °C and 95% relative humidity and allowed to stand for 500 hours before being taken out. Thereafter, as Figure 2 shown, the length (5) of iodine color loss occurring in specimen (1) was measured diagonally from the four corners of the specimen, and the levels of iodine color loss were classified as follows.

[0146] ◎: Less than 1 mm,

[0147] ○: 1 mm or greater than 1 mm but less than 2 mm

[0148] △: 2 mm or greater than 2 mm but less than 3 mm

[0149] ×: 3 mm or greater than 3 mm

[0150] [Table 1]

[0151]

[0152] A) O-cresol novolac epoxy compound (Guodu Chemical Co., Ltd.)

[0153] B) Phenol novolac epoxy compound (Guodu Chemical Co., Ltd.)

[0154] C) 1,4-butanediol diglycidyl ether (Guodu Chemical Co., Ltd.)

[0155] D) Butyl monoglycidyl ether (Daicel Corporation)

[0156] E) Dipropylene glycol diacrylate (Meiyuan Commercial Co., Ltd.)

[0157] F) Triethylene glycol diacrylate (Meiyuan Commercial Co., Ltd.)

[0158] G) 1,9-Nonanediol diacrylate (Kyoeisha Chemical Co., Ltd.)

[0159] H) 1,6-Hexanediol diacrylate (Mihara Shoji Co., Ltd.)

[0160] I) 2-(2-Vinyloxyethoxy)ethyl acrylate (Nippon Shokubai Co., Ltd.)

[0161] [Table 2]

[0162]

[0163] As shown in Table 2, the adhesive composition for a polarizing plate of the present invention has excellent optical transparency in its original state, no haze, exhibits excellent adhesiveness between a polarizing film and a polarizing film protective film, and provides an adhesive layer with excellent reliability by preventing the polarizing film from discoloring after being subjected to high temperature and high humidity conditions.

[0164] On the other hand, the adhesive composition of a comparative example that does not satisfy the configuration of the adhesive composition of the present invention does not provide the effects of the present invention.

[0165] The present invention provides an adhesive composition for a polarizing plate, and the adhesive composition provides an adhesive layer having excellent adhesiveness between a polarizing film and a polarizing film protective film.

[0166] The present invention provides an adhesive composition for a polarizing plate, and the adhesive composition provides an adhesive layer with excellent reliability by preventing the polarizing film from discoloring after being subjected to high temperature and high humidity conditions.

[0167] The present invention provides an adhesive composition for a polarizing plate that has excellent optical transparency and no haze in its original state.

[0168] Those skilled in the art can easily implement simple modifications or changes to the present invention, and all such modifications or changes can be considered to be included within the scope of the present invention.

Claims

1. An adhesive composition for a polarizing plate, comprising: Curable compounds; as well as Photoinitiator, The curable compounds include epoxy compounds and (meth)acrylate compounds. The epoxy compound comprises a mixture of a phenolic epoxy compound and an aliphatic epoxy compound. The (meth)acrylate compound comprises a mixture of a hydrophilic (meth)acrylate compound, a hydrophobic (meth)acrylate compound and a vinyl-containing (meth)acrylate compound, and The vinyl group-containing (meth)acrylate compound is included in an amount of 10 parts by weight to 40 parts by weight based on 100 parts by weight of the curable compound.

2. The adhesive composition according to claim 1, wherein the total amount of the phenolic epoxy compound and the aliphatic epoxy compound is 95 parts by weight or more based on 100 parts by weight of the epoxy compound. 3 . The adhesive composition according to claim 1 , wherein the novolac epoxy-based compound is included in an amount of 10 parts by weight to 40 parts by weight based on 100 parts by weight of the curable compound.

4. The adhesive composition according to claim 1, wherein the aliphatic epoxy compound comprises one or more of the following: a monoglycidyl ether compound having a linear alkyl chain containing four or more carbon atoms, a diglycidyl ether compound having a linear alkylene chain containing four or more carbon atoms, and a diglycidyl ether compound having 2 moles or more of ethylene oxide or propylene oxide in its molecule. 5 . The adhesive composition according to claim 1 , wherein the aliphatic epoxy-based compound is included in an amount of 10 parts by weight to 40 parts by weight based on 100 parts by weight of the curable compound. 6 . The adhesive composition according to claim 1 , wherein the hydrophobic (meth)acrylate-based compound comprises an unsubstituted bifunctional (meth)acrylate compound having a linear alkylene group having 6 or more carbon atoms. 7 . The adhesive composition according to claim 1 , wherein the hydrophobic (meth)acrylate-based compound is included in an amount of 10 parts by weight to 40 parts by weight based on 100 parts by weight of the curable compound. 8 . The adhesive composition according to claim 1 , wherein the hydrophobic (meth)acrylate-based compound is included in an amount of 50 parts by weight to 200 parts by weight based on 100 parts by weight of the aliphatic epoxy-based compound. 9 . The adhesive composition according to claim 1 , wherein the hydrophilic (meth)acrylate-based compound comprises a bifunctional (meth)acrylate-based compound having an alkylene oxide group between (meth)acrylate groups.

10. The adhesive composition according to claim 1, wherein the vinyl-containing (meth)acrylate compound is a compound represented by the following Chemical Formula 2: Chemical formula 2 In chemical formula 2, R is hydrogen or methyl, and n is an integer from 1 to 5.

11. The adhesive composition according to claim 1, wherein the total amount of the vinyl-containing (meth)acrylate compound, the hydrophilic (meth)acrylate compound and the hydrophobic (meth)acrylate compound is 95 parts by weight or more, based on 100 parts by weight of the (meth)acrylate compound. 12 . The adhesive composition according to claim 1 , wherein the total amount of the epoxy compound and the (meth)acrylate compound is 95 parts by weight or more based on 100 parts by weight of the curable compound. 13 . The adhesive composition according to claim 1 , wherein the curable compound is included in an amount of 90 wt % or more based on a solid content in the adhesive composition for a polarizing plate.

14. A polarizing plate, comprising: Polarizer; as well as a protective film laminated on the lower surface of the polarizer, wherein the polarizer and the protective film are laminated via an adhesive layer, and The adhesive layer includes a cured product of the adhesive composition for a polarizing plate according to any one of claims 1 to 13 .

15. An optical display device comprising the polarizing plate according to claim 14.

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