Polarizer, adhesive film for polarizer, and display device

Abstract

To provide a polarizer in which reworkability and durability are simultaneously improved despite a weak peel strength between a liquid crystal phase difference layer and an alignment film.SOLUTION: A polarizer comprises a polarizer element, a liquid crystal phase difference layer sequentially laminated on one surface of the polarizer element, and an adhesive film for polarizer. The adhesive film for polarizer has a modulus of 50 kPa to 1000 kPa at 25°C and a tackiness of 50 gf to 150 gf. The adhesive film for polarizer includes a cured product of a composition containing a curable component and an initiator. The curable component includes a mixture containing an aliphatic oligomer; one or more of alicyclic or heteroalicyclic oligomers, aromatic oligomers, and combinations of alicyclic or heteroalicyclic oligomers and aromatic oligomers; and a comonomer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a polarizing plate, an adhesive film for a polarizing plate, and a display device including the same. [Background technology]

[0002] The polarizer for OLEDs may include a liquid crystal retardation layer to provide anti-reflection properties. The liquid crystal retardation layer may be fabricated by coating and aligning liquid crystal on an alignment film, and then crosslinking the liquid crystal by irradiating it with light such as ultraviolet light.

[0003] Liquid crystals are classified into normal wavelength dispersion liquid crystals and reverse wavelength dispersion liquid crystals based on their wavelength dispersion characteristics. Reverse wavelength dispersion liquid crystals are generally known to have superior optical properties, such as improved lateral hue, compared to normal wavelength dispersion liquid crystals. However, because reverse wavelength dispersion liquid crystal layers are made of discotic liquid crystals and have rigid properties, they can have low peel strength between the liquid crystal layer and alignment film. This can result in a disadvantage of weakening the interlayer peel strength when manufacturing optical laminates such as polarizers.

[0004] It would be desirable to provide a polarizing plate that has excellent reworkability and durability despite the weak peeling force between the liquid crystal retardation layer and the alignment film.

[0005] The background art of the present invention is disclosed in Patent Document 1 and the like. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Korean Patent Publication No. 2015-0010567 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a polarizing plate which has improved reworkability and durability at the same time, despite the weak peeling force between the liquid crystal retardation layer and the alignment film. [Means for solving the problem]

[0008] According to one embodiment, a polarizer is provided.

[0009] The polarizing plate includes a polarizer, a liquid crystal retardation layer sequentially laminated on one surface of the polarizer, and an adhesive film for the polarizing plate. The adhesive film for the polarizing plate has a modulus of 50 kPa to 1000 kPa at 25°C and a tackiness of 50 gf to 150 gf, and includes a cured product of a composition including a curable component and an initiator. The curable component includes a mixture containing at least one of an aliphatic oligomer, an alicyclic or heteroalicyclic oligomer, an aromatic oligomer, or a combination of an alicyclic or heteroalicyclic oligomer and an aromatic oligomer, and a comonomer.

[0010] According to one embodiment, an adhesive film for a polarizing plate is provided.

[0011] The adhesive film for polarizing plates has a modulus of 50 kPa to 1000 kPa at 25°C and a tackiness of 50 gf to 150 gf, and includes a cured product of a composition including a curable component and an initiator, and the curable component includes a mixture containing at least one of an aliphatic oligomer, an alicyclic or heteroalicyclic oligomer, an aromatic oligomer, or a combination of an alicyclic or heteroalicyclic oligomer and an aromatic oligomer, and a comonomer.

[0012] According to one embodiment, a display device is provided.

[0013] The display device includes the polarizing plate. [Effects of the Invention]

[0014] The present invention can provide excellent reworkability because there is no peeling between the liquid crystal retardation layer and the alignment film when reworking after adhering the polarizing plate to a panel, even though the peeling force between the liquid crystal retardation layer and the alignment film is weak.

[0015] Furthermore, even if the peeling force between the liquid crystal retardation layer and the alignment film is weak, the present invention does not cause peeling between the liquid crystal retardation layer and the alignment film, so that the reliability at high temperature or high temperature and high humidity can be excellent. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view of a polarizing plate according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view of a polarizing plate according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] With reference to the accompanying drawings, the present invention will be described in detail with respect to the embodiments so that those skilled in the art can easily carry out the invention. The present invention may be embodied in various different forms and is not limited to the embodiments described herein. In the drawings, parts that are not relevant to the description are omitted to clearly explain the present invention, and the same reference numerals are used throughout the specification to refer to the same or similar components. In the drawings, the length, thickness, etc. of each component are shown for the purpose of explaining the present invention, and the present invention is not limited to the length, thickness, etc. shown in the drawings.

[0018] The terms used herein are for the purpose of describing exemplary embodiments only and are not intended to limit the present invention. The singular expressions include the plural expressions unless the context clearly dictates otherwise.

[0019] In this specification, "upper" and "lower" are based on the drawings and are not necessarily fixed as upper and lower, and "upper" may be changed to "lower" and "lower" to "upper" depending on the viewpoint.

[0020] In this specification, "in-plane retardation (Re)" is represented by the following mathematical formula A. [Formula A] Re = (nx - ny) × d ··· (A) (In the above formula A, nx and ny are the refractive indices in the slow axis direction and the fast axis direction of the optical element at the measurement wavelength, respectively, and d is the thickness of the optical element (unit: nm).)

[0021] In this specification, "inverse wavelength dispersibility" means that Re(450) < Re(550) < Re(650).

[0022] In this specification, "(meth)acryl" means acrylic and / or methacrylic.

[0023] In this specification, the "glass transition temperature of the homopolymer" may mean the glass transition temperature (Tg) measured using TA Instrument's DSC Discovery for the homopolymer of the monomer to be measured. Specifically, after raising the temperature of the homopolymer of the monomer to be measured to 180°C at a rate of 20°C / min, cooling it to -100°C while gradually cooling, and then heating it to 100°C at a rate of 10°C / min, the endothermic transition curve obtained as data can be used to determine the inflection point of the endothermic transition curve as the glass transition temperature.

[0024] In this specification, "modulus" means the storage modulus measured at 25°C and the value measured by the CSS (Controlled Shear Stress) method.

[0025] In this specification, "tackiness" means the value measured at 25°C and the value measured by the probe tack test (ASTM D2979) method.

[0026] In this specification, when describing a range of numerical values, "X to Y" means at least X and at most Y (X≦and≦Y).

[0027] The adhesive film for a polarizer according to an embodiment may be applied to a polarizer having a liquid crystal retardation layer, and may be used to bond each liquid crystal retardation layer to each other.

[0028] At least one of the liquid crystal retardation layers may have an alignment film on one surface of the liquid crystal retardation layer, and the peel strength between the liquid crystal retardation layer and the alignment film may be 50 gf / 25 mm or less.

[0029] When the peel strength between the liquid crystal retardation layer and the alignment film is 50 gf / 25 mm or less, when the polarizer is adhered to a panel and then reworked, the polarizer is not completely separated from the panel due to the weak peel strength between the liquid crystal retardation layer and the alignment film, and a portion of the polarizer remains on the panel. Increasing the peel strength between the liquid crystal retardation layer and the alignment film to more than 50 gf / 25 mm may be considered. However, there is a limit to how much the peel strength can be increased, and changing the composition of the liquid crystal retardation layer or the alignment film to increase the peel strength may not reliably achieve the desired retardation.

[0030] According to an embodiment, the peel strength between the liquid crystal retardation layer and the alignment film of the polarizer may be more than 0 gf / 25 mm and less than 50 gf / 25 mm, 1 gf / 25 mm to 50 gf / 25 mm, and 5 gf / 25 mm to 20 gf / 25 mm.

[0031] The adhesive film for polarizing plates is laminated on the alignment film side of a liquid crystal retardation layer having a peel strength of 50 gf / 25 mm or less from the alignment film, so that when the above-mentioned polarizing plate is reworked after adhering to a panel, there is no peeling between the liquid crystal retardation layer and the alignment film, and therefore excellent reworkability can be provided.

[0032] Furthermore, since the adhesive film for polarizing plates is laminated on the alignment film side of a liquid crystal retardation layer having a peel strength to the alignment film of 50 gf / 25 mm or less, there is no peeling between the liquid crystal retardation layer and the alignment film when the polarizing plate is left at high temperature or high temperature and high humidity for a long period of time, and therefore excellent reliability at high temperature or high temperature and high humidity can be provided.

[0033] The adhesive film for polarizing plates has a modulus of 50 kPa to 1000 kPa at 25°C, a tackiness of 50 gf to 150 gf, and includes a cured product of a composition including a curable component and an initiator, and the curable component includes a mixture containing at least one of an aliphatic oligomer, an alicyclic or heteroalicyclic oligomer, an aromatic oligomer, or a combination of an alicyclic or heteroalicyclic oligomer and an aromatic oligomer, and a comonomer.

[0034] The adhesive film for polarizing plates may have a haze of 1% or less, specifically 0% to 1%, in the visible light region, for example, at a wavelength of 550 nm. Within this range, the adhesive film for polarizing plates may be used in display devices.

[0035] The adhesive film for polarizing plates may have a thickness of 5 μm to 50 μm, specifically 5 μm to 35 μm, in which case the adhesive film for polarizing plates can be used for polarizing plates.

[0036] Hereinafter, an adhesive film for a polarizing plate according to an embodiment will be described.

[0037] The pressure-sensitive adhesive film for polarizing plates contains a cured product of the composition.

[0038] In one specific example, the pressure-sensitive adhesive film for polarizing plates may be a photocured product.

[0039] In one embodiment, the PSA film for polarizing plates may include at least one of an aliphatic oligomer, an alicyclic or heteroalicyclic oligomer, an aromatic oligomer, or a combination of an alicyclic or heteroalicyclic oligomer and an aromatic oligomer, a comonomer, and at least one initiator, which may be derived from the composition.

[0040] The adhesive film has a modulus of 50 kPa to 1000 kPa at 25°C. When the modulus of the adhesive film is 50 kPa or more, an appropriate peeling force between the liquid crystal retardation layers is ensured, and peeling between the liquid crystal retardation layers may not occur during rework even at high temperatures or high temperatures and humidity. When the modulus of the adhesive film is 1000 kPa or less, the force applied between the liquid crystal retardation layer and the alignment film during rework is reduced, and peeling between the liquid crystal retardation layer and the alignment film does not occur, allowing for successful rework. For example, the adhesive film may have a modulus of 50 kPa to 500 kPa or 50 kPa to 300 kPa at 25°C.

[0041] The adhesive film has a tackiness of 50 gf to 150 gf. In this range, the adhesive film can enhance adhesion to the alignment film. Furthermore, by reducing the force applied between the liquid crystal retardation layer and the alignment film during rework, peeling between the liquid crystal retardation layer and the alignment film can be prevented, allowing for successful rework. For example, the tackiness may be 80 gf to 150 gf, 90 gf to 150 gf, or 90 gf to 130 gf.

[0042] The pressure-sensitive adhesive film for polarizing plates includes a cured product of a composition including a curable component and an initiator, and the curable component includes a mixture including at least one of an aliphatic oligomer, an alicyclic or heteroalicyclic oligomer, an aromatic oligomer, or a combination of an alicyclic or heteroalicyclic oligomer and an aromatic oligomer, and a comonomer.

[0043] As used herein, the term "oligomer" may refer to a polymer of a monomer having a weight-average molecular weight of 10,000 g / mol or less, for example, 1,000 g / mol to 10,000 g / mol. Here, the "weight-average molecular weight" may be measured using gel permeation chromatography in terms of polystyrene.

[0044] According to one embodiment, the mixture may be included in the curable component at 95% by weight or more, for example, 95% to 100% by weight, 98% to 100% by weight, and 100% by weight.

[0045] Aliphatic Oligomers The aliphatic oligomer contained in the composition can facilitate the adhesive film to reach the modulus and tackiness ranges, and can provide a high peel strength between the adhesive film and the alignment film.

[0046] The aliphatic oligomer may include an oligomer of a (meth)acrylic monomer having a substituted or unsubstituted, linear or branched alkyl group having 4 to 10 carbon atoms.

[0047] As used herein, "substituted or unsubstituted" may mean that one or more hydrogen atoms of the functional group are substituted with an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, an amino group, a hydroxy group, a cyano group, a halogen atom, or the like.

[0048] For example, the (meth)acrylic monomer may include, but is not limited to, one or more of substituted or unsubstituted n-butyl (meth)acrylate, t-butyl (meth)acrylate, iso-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, heptyl (meth)acrylate, n-octyl (meth)acrylate, iso-octyl (meth)acrylate, nonyl (meth)acrylate, and decyl (meth)acrylate. These may be contained alone in the aliphatic oligomer, or two or more may be mixed and contained in the aliphatic oligomer. For example, the (meth)acrylic monomer may be 2-ethylhexyl (meth)acrylate.

[0049] The aliphatic oligomer may be included in the mixture in an amount of 1 to 30% by weight. This range allows the PSA film to easily achieve the modulus range described above. For example, the aliphatic oligomer may be included in the mixture in an amount of 5 to 25% by weight, 5 to 20% by weight, or 10 to 20% by weight.

[0050] One or more of alicyclic or heteroalicyclic oligomers, aromatic oligomers, and combinations of alicyclic or heteroalicyclic oligomers and aromatic oligomers The composition contains at least one of the alicyclic or heteroalicyclic oligomer, aromatic oligomer, or a combination of the alicyclic or heteroalicyclic oligomer and aromatic oligomer, which can facilitate the PSA film to reach the modulus and tackiness ranges, and can provide a high peel strength between the PSA film and the alignment film.

[0051] In one embodiment, the mixture can comprise the alicyclic or heteroalicyclic oligomer alone.

[0052] In one embodiment, the mixture can contain the aromatic oligomer alone.

[0053] In one embodiment, the mixture can include a combination of the alicyclic or heteroalicyclic oligomers and aromatic oligomers.

[0054] In one embodiment, the mixture can include a mixture of the alicyclic or heteroalicyclic oligomer and the aromatic oligomer.

[0055] For example, the mixture can include the alicyclic or heteroalicyclic oligomer and an aromatic oligomer.

[0056] The monomer for the alicyclic or heteroalicyclic oligomer may include one or more (meth)acrylic acid esters having an alicyclic group or a heteroalicyclic group at the ester moiety.

[0057] The (meth)acrylic acid ester having a polycyclic alicyclic group, such as a monocyclic or dicyclic group, consisting of only carbon atoms in the ester moiety may include a (meth)acrylic acid ester having an alicyclic group having 5 to 15 carbon atoms. For example, the (meth)acrylic acid ester may include one or more of isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, and bornyl (meth)acrylate, and may include, for example, isobornyl (meth)acrylate.

[0058] The (meth)acrylic acid ester having a heteroalicyclic group can include a (meth)acrylic acid ester having a heteroalicyclic group having 3 to 10 carbon atoms and a heteroatom in the ester moiety. Here, the "heteroatom" may be oxygen (O), nitrogen (N), or sulfur (S), preferably oxygen. For example, the (meth)acrylic acid ester can include tetrahydrofurfuryl (meth)acrylate.

[0059] For example, the (meth)acrylic acid ester may include one or more of isobornyl (meth)acrylate and tetrahydrofurfuryl (meth)acrylate.

[0060] The monomer for the aromatic oligomer may include one or more (meth)acrylic acid esters having an aromatic group at the ester moiety. For example, the (meth)acrylic acid ester may be represented by the following Chemical Formula 1: [C1] (CH2=)-C(R 1 )-C(=O)-O-(-CH2-)sL 11 ...(Formation 1) (In the above Chemical Formula 1, R 1 is hydrogen or an alkyl group having 1 to 5 carbon atoms, s is an integer from 0 to 10, L 11 is a substituted or unsubstituted C to C 50 or a substituted or unsubstituted C to C 50 is an aryloxy group).

[0061] For example, L 11is a phenylphenoxyethyl group, a phenoxyethyl group, a benzyl group, a phenyl group, a phenylphenoxy group, a phenoxy group, a phenylethyl group, a phenylpropyl group, a phenylbutyl group, a methylphenylethyl group, a propylphenylethyl group, a methoxyphenylethyl group, a cyclohexylphenylethyl group, a chlorophenylethyl group, a bromophenylethyl group, a methylphenyl group, a methylethylphenyl group, a methoxyphenyl group, a propylphenyl group, a cyclohexylphenyl group, a chlorophenyl group, a bromophenyl group, a phenylphenyl group, a biphenyl group, a terphenyl group, and a quaterphenyl group. , anthracenyl group, naphthalenyl group, triphenylenyl group, methylphenoxy group, ethylphenoxy group, methylethylphenoxy group, methoxyphenyloxy group, propylphenoxy group, cyclohexylphenoxy group, chlorophenoxy group, bromophenoxy group, biphenyloxy group, terphenyloxy group, quaterphenyloxy group, anthracenyloxy group, naphthalenyloxy group, and triphenylenyloxy group.

[0062] Specifically, the (meth)acrylic acid esters include 2-phenylphenoxyethyl (meth)acrylate, naphthyl (meth)acrylate, naphthalenylmethyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenyl (meth)acrylate, phenoxy (meth)acrylate, 2-ethylphenoxy (meth)acrylate, benzyl (meth)acrylate, 2-phenylethyl (meth)acrylate, 3-phenylpropyl (meth)acrylate, 4-phenylbutyl (meth)acrylate, 2-(2-methylphenyl)ethyl (meth)acrylate, Acrylate, 2-(3-methylphenyl)ethyl (meth)acrylate, 2-(4-methylphenyl)ethyl (meth)acrylate, 2-(4-propylphenyl)ethyl (meth)acrylate, 2-(4-(1-methylethyl)phenyl)ethyl (meth)acrylate, 2-(4-methoxyphenyl)ethyl (meth)acrylate, 2-(4-cyclohexylphenyl)ethyl (meth)acrylate, 2-(2-chlorophenyl)ethyl (meth)acrylate, 2-(3-chlorophenyl)ethyl (meth)acrylate, 2-(4-chlorophenyl)ethyl butyl (meth)acrylate, 2-(4-bromophenyl)ethyl (meth)acrylate, 2-(3-phenylphenyl)ethyl (meth)acrylate, 4-(biphenyl-2-yloxy)butyl (meth)acrylate, 3-(biphenyl-2-yloxy)butyl (meth)acrylate, 2-(biphenyl-2-yloxy)butyl (meth)acrylate, 1-(biphenyl-2-yloxy)butyl (meth)acrylate, 4-(biphenyl-2-yloxy)propyl (meth)acrylate, 3-(biphenyl-2-yloxy)propyl (meth)acrylate Acrylate, 2-(biphenyl-2-yloxy)propyl (meth)acrylate, 1-(biphenyl-2-yloxy)propyl (meth)acrylate, 4-(biphenyl-2-yloxy)ethyl (meth)acrylate, 3-(biphenyl-2-yloxy)ethyl (meth)acrylate, 2-(biphenyl-2-yloxy)ethyl (meth)acrylate, 1-(biphenyl-2-yloxy)ethyl (meth)acrylate, 2-(4-benzylphenyl)ethyl (meth)acrylate, 1-(4-benzylphenyl)ethyl (meth)acrylate,and one or more of these structural isomers, but is not limited thereto. That is, the (meth)acrylates mentioned in the present invention are merely examples and are not limited thereto. Furthermore, the present invention includes all acrylates that are structural isomers. For example, even if only 2-phenylethyl (meth)acrylate is mentioned as an example of the present invention, the present invention includes all isomers including 3-phenylethyl (meth)acrylate and 4-phenyl (meth)acrylate.

[0063] Preferably, in the (meth)acrylic acid ester, L of the formula 1 11 is a substituted or unsubstituted C to C 50 The aryloxy group may be a monomer.

[0064] The monomers for the alicyclic or heteroalicyclic oligomer and aromatic oligomer may be at least one selected from the monomers for the alicyclic or heteroalicyclic oligomer described above and at least one selected from the monomers for the aromatic oligomer described above. For example, the monomers for the alicyclic or heteroalicyclic oligomer and aromatic oligomer may include isobornyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and phenoxyethyl acrylate.

[0065] The mixture may contain at least one of the alicyclic or heteroalicyclic oligomer, aromatic oligomer, or combination of the alicyclic or heteroalicyclic oligomer and aromatic oligomer in an amount of 1 to 30% by weight. This range allows the PSA film to easily achieve the modulus range described above. For example, the mixture may contain at least one of the alicyclic or heteroalicyclic oligomer, aromatic oligomer, alicyclic or heteroalicyclic oligomer, and aromatic oligomer in an amount of 5 to 25% by weight, 5 to 20% by weight, or 10 to 20% by weight.

[0066] The total content of the aliphatic oligomer and one or more of the alicyclic or heteroalicyclic oligomer, aromatic oligomer, and combinations of the alicyclic or heteroalicyclic oligomer and aromatic oligomer may be 10 wt % or more in the mixture. Within this range, the modulus of the PSA film does not become excessively high, thereby providing excellent reworkability. For example, the total content may be 10 wt % to 50 wt %, e.g., 10 wt % to 40 wt %, in the mixture.

[0067] Comonomer The comonomer may form a matrix of the adhesive film, while ensuring peel strength of the adhesive film to the liquid crystal retardation layer and / or alignment film.

[0068] The comonomer may be selected from the monomers for the alicyclic or heteroalicyclic oligomers and the monomers for the aromatic oligomers. For example, the comonomer may be a mixture of the monomers for the alicyclic or heteroalicyclic oligomers and the monomers for the aromatic oligomers. For example, the comonomer may be a mixture of tetrahydrofurfuryl (meth)acrylate and phenoxyethyl (meth)acrylate.

[0069] The comonomer may be included in the mixture in an amount of 50 to 90% by weight. This range allows the PSA film to easily achieve the modulus range described above. For example, the comonomer may be included in the mixture in an amount of 55 to 85% by weight, or 60 to 80% by weight.

[0070] The initiator may include a photoinitiator.

[0071] The photoinitiator may serve to polymerize the monomer mixture through a photoinitiated reaction. As the photoinitiator, a conventional photoinitiator may be used, such as a phosphorus-based photoinitiator or a hydroxycyclohexyl ketone-based photoinitiator.

[0072] The photoinitiator may be included in an amount of 1 to 10 parts by weight, for example, 2 to 6 parts by weight, based on 100 parts by weight of the mixture. This range allows the reaction of the photoinitiator to proceed sufficiently and prevents the remaining amount from deteriorating the light transmittance of the PSA film.

[0073] The composition may further contain additives commonly contained in adhesive films for polarizing plates, such as silane compounds (including silane coupling agents), dyes, pigments, UV absorbers, heat stabilizers, antioxidants, surface modifiers, dispersants, and antistatic agents.

[0074] A polarizing plate according to an embodiment includes the adhesive film for a polarizing plate.

[0075] The polarizing plate includes a polarizer and the pressure-sensitive adhesive film for polarizing plates laminated on at least one surface of the polarizer.

[0076] In one specific example, the polarizing plate includes a polarizer, a liquid crystal retardation layer laminated on one surface of the polarizer, and an adhesive film for a polarizing plate.

[0077] The adhesive film for polarizing plates has been described above, and therefore further description is omitted.

[0078] Polarizer A polarizer can polarize light incident from outside the polarizer or light incident from inside the polarizer.

[0079] The polarizer may include a polyvinyl alcohol-based polarizer obtained by dyeing a polyvinyl alcohol-based film with iodine or the like. For example, a polyvinyl alcohol-based polarizer is manufactured by dyeing a polyvinyl alcohol film with iodine or a dichroic dye and stretching the dye in a specific direction. Specifically, the polarizer is manufactured through a swelling process, a dyeing step, and a stretching step. Methods for performing each step are generally known to those skilled in the art.

[0080] The polarizer may have a thickness of 1 μm to 50 μm, and within this range, the polarizer can be used in a display device.

[0081] The polarizing plate may include a liquid crystal retardation layer on at least one surface of the polarizer.

[0082] liquid crystal retardation layer The liquid crystal retardation layer circularly polarizes linearly polarized light emitted after passing through a polarizer, thereby preventing reflection of the external light and realizing an anti-reflection function, thereby improving the appearance and screen quality.

[0083] In one specific example, the liquid crystal retardation layer has an in-plane retardation of 100 nm to 220 nm, specifically 100 nm to 180 nm, for example, λ / 4, at a wavelength of 550 nm (first retardation layer). Within this range, the reflectance to external light can be reduced, and the screen quality can be improved.

[0084] In another specific example, the liquid crystal retardation layer may have a retardation in the in-plane direction at a wavelength of 550 nm of 225 nm to 350 nm, specifically 225 nm to 300 nm, for example, a retardation of λ / 2 (second retardation layer). Within this range, the reflectance to external light can be reduced, and the screen quality can be improved.

[0085] In yet another specific example, the retardation layer may be a laminate of the first retardation layer and the second retardation layer.

[0086] In one embodiment, the retardation layer can exhibit reverse wavelength dispersion.

[0087] In one embodiment, the retardation layer may have a thickness of 0.1 μm to 10 μm, for example, 1 μm to 5 μm, which allows the polarizer to be thinned and achieve a desired retardation.

[0088] In one embodiment, the liquid crystal retardation layer may be formed of a composition containing a liquid crystal compound having one or more of an aromatic functional group and an alicyclic functional group. In one embodiment, the liquid crystal compound may be a polymer, oligomer, or monomer containing a unit composed of an aromatic ring and a polymerizable functional group that can impart liquid crystallinity. The polymerizable functional group may be a (meth)acryloyl group, an epoxy group, a vinyl ether group, or the like, and may be cured by heat or light, thereby increasing the strength of the liquid crystal retardation layer.

[0089] The composition may be formed of a composition containing the liquid crystal compound described above. The composition may further contain additives such as a leveling agent, a polymerization initiator, an alignment aid, a heat stabilizer, a lubricant, a plasticizer, and an antistatic agent, and the details of these additives may be found in those known to those skilled in the art.

[0090] In one embodiment, the liquid crystal retardation layer may be a discotic liquid crystal layer.

[0091] The liquid crystal retardation layer may have an alignment film for the liquid crystal retardation layer on at least one surface thereof. For example, the liquid crystal retardation layer may have an alignment film for the liquid crystal retardation layer on the pressure-sensitive adhesive film for polarizing plate side.

[0092] Alignment film for liquid crystal retardation layer The alignment film for the liquid crystal retardation layer can enable the liquid crystal retardation layer to realize a desired retardation. The alignment film may be made of a conventional material known to those skilled in the art.

[0093] The peel strength between the liquid crystal retardation layer and the alignment film is 50 gf / 25 mm or less. A laminate between a liquid crystal retardation layer and an alignment film having such a peel strength can be used as a commercially available product.

[0094] The polarizing plate may further include a protective layer on at least one surface of the polarizer.

[0095] protective layer The protective layer is formed on at least one surface of the polarizer to protect the polarizer or to provide an additional function to the polarizing plate.

[0096] The protective layer may include one or more of an optically transparent protective film and a protective coating layer.

[0097] When the protective layer is in the form of a protective film, it may include a protective film formed of an optically transparent resin. The protective film may be formed by melting and extruding the resin. If necessary, a stretching process may be further added. The resin may include one or more of cellulose ester-based resins including triacetyl cellulose, cyclic polyolefin-based resins including cyclic olefin polymers (COP), polycarbonate-based resins, polyester-based resins including polyethylene terephthalate (PET), polyethersulfone-based resins, polysulfone-based resins, polyamide-based resins, polyimide-based resins, acyclic polyolefin-based resins, polyacrylate-based resins including polymethyl methacrylate resin, polyvinyl alcohol-based resins, polyvinyl chloride-based resins, and polyvinylidene chloride-based resins. Preferably, the protective film may be a film formed of a cyclic polyolefin-based resin including cyclic polyolefin.

[0098] When the protective layer is in the form of a protective coating layer, it can have good adhesion to the polarizer, transparency, mechanical strength, thermal stability, moisture blocking properties, and durability. In one embodiment, the protective coating layer for the protective layer may be formed of an active energy ray-curable resin composition including an active energy ray-curable compound and a polymerization initiator.

[0099] 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-based compound having at least one epoxy group in the molecule, or an oxetane-based compound having at least one oxetane ring in the molecule. The radically polymerizable curable compound may be a (meth)acrylic-based compound having at least one (meth)acryloyloxy group in the molecule.

[0100] The thickness of the protective layer is 5 μm to 200 μm, specifically 30 μm to 120 μm, and may be 50 μm to 100 μm in the form of a protective film or 5 μm to 50 μm in the form of a protective coating layer. The protective layer in this range can be used in an optical display device.

[0101] The protective layer may include a functional coating layer formed on at least one surface thereof or may be surface-treated. The functional coating layer may be, but is not limited to, a hard coating layer, an anti-fingerprint layer, an anti-reflection layer, a low-reflection layer, an ultra-low-reflection layer, an anti-glare layer, etc. The surface treatment may be, but is not limited to, a corona treatment.

[0102] The protective layer may be attached to a polarizer or an adherend other than a polarizer by an adhesive layer. The adhesive layer may be formed of, but is not limited to, a water-based adhesive or a photo-curable adhesive. The water-based adhesive and the photo-curable adhesive may be appropriately used in accordance with the knowledge of those skilled in the art.

[0103] The polarizing plate may include one or more adhesive layers, and the polarizing plate may include one or more adhesive layers, or two or more adhesive layers.

[0104] adhesive layer The adhesive layer can fix the polarizing plate to the panel for a display device.

[0105] In one embodiment, the pressure sensitive adhesive layer may be a pressure sensitive adhesive (PSA). For example, the pressure sensitive adhesive layer may include a cured product of a composition including an adhesive resin and a curing agent.

[0106] 1 and 2 are cross-sectional views of a polarizing plate according to an embodiment.

[0107] Referring to FIG. 1, the polarizing plate may include a polarizer 100, a protective layer 200 laminated on an upper surface of the polarizer, a lower protective layer 300 sequentially laminated on a lower surface of the polarizer, a first liquid crystal retardation layer 410, an alignment film 420 for the first liquid crystal retardation layer, and an adhesive film 500 for the polarizing plate.

[0108] Referring to FIG. 2, the polarizing plate may include a polarizer 100, a protective layer 200 laminated on an upper surface of the polarizer, a lower protective layer 300 sequentially laminated on a lower surface of the polarizer, a first liquid crystal retardation layer 410, an alignment film 420 for the first liquid crystal retardation layer, an adhesive film 500 for the polarizing plate, and a second liquid crystal retardation layer 600.

[0109] Although not shown in FIGS. 1 and 2, the polarizing plate may further include one or more of a polarizer protective film, an anti-reflection film, a retardation film (liquid crystal layer or non-liquid crystal layer), and an adhesive film, which are commonly used in polarizing plates.

[0110] 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 having a light-emitting element, a liquid crystal display device, or the like.

[0111] The present invention will be described in more detail with reference to the following examples, which are provided for the purpose of facilitating understanding of the present invention and are not intended to limit the scope of the present invention.

[0112] The types of the first liquid crystal retardation layers used in the following examples and comparative examples are as follows. A: MR4ND-I (DNP) (a laminate of liquid crystal retardation layer, alignment film, and PET substrate film) B: A-01 (SDI) (LCD retardation layer - alignment film - PET substrate film laminate) C: A-02 (SDI) (LCD retardation layer - alignment film - PET substrate film laminate) D: MCP-I (DNP) (a laminate of liquid crystal retardation layer, alignment film, and PET substrate film)

[0113] The laminates A to C are used for the first liquid crystal retardation layer. The liquid crystal retardation layers in the laminates all provide an in-plane retardation of 1 / 2 at a wavelength of 550 nm.

[0114] The laminate D is used for the second liquid crystal retardation layer. The liquid crystal retardation layer of the laminate provides an in-plane retardation of 1 / 4 at a wavelength of 550 nm.

[0115] In A to C, the peel force between the liquid crystal retardation layer and the alignment film was measured. The peel force is the load applied when peeling the liquid crystal retardation layer from a laminate of an alignment film and a PET substrate film. Specifically, the peel force is measured when a polarizing plate is manufactured as in Example 1 below, the manufactured polarizing plate is attached to a glass plate, the gap between the liquid crystal retardation layer and the alignment film is widened at 25°C, and the upper polarizer protective film, polarizer, and liquid crystal retardation layer are peeled from the alignment film at a peel angle of 90°. The detailed measurement conditions are as follows. The measurement results are shown in Table 1 below (unit: gf / 25 mm). Measurement equipment: UTM (INSTRON) Peeling speed: 5mm / sec Pulling distance: 80mm Sample size: 25mm x 120mm

[0116] Example 1 (1) Production of a composition for adhesive films for polarizing plates A mixture was prepared by mixing 10 parts by weight of an aliphatic acrylic oligomer, 10 parts by weight of an alicyclic acrylic oligomer, and 80 parts by weight of a comonomer. Photoinitiators TPO and Irgacure-184 were added to the mixture in an amount of 2 parts by weight each based on 100 parts by weight of the monomer mixture, to prepare a composition for a pressure-sensitive adhesive film for a polarizing plate.

[0117] (2) Manufacture of polarizing plates A polyvinyl alcohol film (TS20, Mitsubishi Chemical Corporation, degree of polymerization: 2800, thickness: 20 μm) was immersed in a 0.3% potassium iodide aqueous solution to dye it, and then stretched in the machine direction (MD) at a uniaxial stretch ratio of 5.0. The stretched polyvinyl alcohol film was immersed in a 3% boric acid aqueous solution and a 2% potassium iodide aqueous solution to correct the color tone, and then dried at 50°C for 4 minutes to produce a polarizer (light transmittance: 45%, thickness: 7 μm).

[0118] A cyclic olefin polymer film (thickness: 25 μm, Zeon) with a hard coating layer formed on its upper surface was prepared as an upper polarizer protective film, and the lower surface of the film was subjected to corona treatment using a corona treater (AFS) at a speed of 10 mpm and an output of 1000 W.

[0119] As a lower polarizer protective film, a triacetyl cellulose film (thickness: 40 μm, Konica Minolta, normal TAC) was subjected to a saponification treatment.

[0120] A polyvinyl alcohol resin (Z200, average degree of polymerization: 1200, degree of saponification: 98.5 mol%, contains acetoacetyl groups, degree of acetoacetylation: 5 mol%, Mitsubishi Chemical Corporation) was dissolved in water at 95°C for 60 minutes and then cooled completely to room temperature to produce a polyvinyl alcohol resin aqueous solution. Then, 0.1 parts by weight of a zirconium-containing crosslinker, Zircosol-ZN (Daiichi Kigenso Kagaku Kogyo Co., Ltd.), was added and mixed with 100 parts by weight of the polyvinyl alcohol resin aqueous solution to produce a water-based adhesive.

[0121] The aqueous adhesive prepared above was applied to both sides of the produced polarizer to a predetermined thickness, and the upper polarizer protective film was attached to one side and a triacetyl cellulose-based film to the other side at the same time. The resulting film was dried at 80°C for 3 minutes to produce a laminate in which the COP film, adhesive layer, polarizer, adhesive layer, and TAC film were stacked in this order.

[0122] The prepared aqueous adhesive was applied to the lower surface of the TAC film in the laminate, and the liquid crystal retardation layer of the liquid crystal retardation film A was attached thereto. After drying at 80°C for 3 minutes, the PET substrate film was peeled off to prepare a laminate in the following order: COP film-adhesive layer-polarizer-adhesive layer-TAC film-adhesive layer-first liquid crystal retardation layer-alignment film.

[0123] The adhesive film composition prepared above was applied to one side of the alignment film of the laminate in a predetermined thickness, and the liquid crystal retardation layer of the liquid crystal retardation film D was attached thereto. After photo-curing, the PET base film was peeled off to produce a polarizing plate laminated in the following order: COP film - adhesive layer - polarizer - adhesive layer - TAC film - adhesive layer - first liquid crystal retardation layer - alignment film - adhesive film for polarizing plate - second liquid crystal retardation layer - alignment film.

[0124] Example 2 A polarizing plate was manufactured in the same manner as in Example 1, except that the content of each component in the adhesive film in Example 1 was changed as shown in Table 1 below.

[0125] Examples 3 and 4 A polarizing plate was manufactured in the same manner as in Example 1, except that the content of each component in the first liquid crystal retardation layer and the adhesive film in Example 1 was changed as shown in Table 1 below.

[0126] Comparative Examples 1 to 3 A polarizing plate was manufactured in the same manner as in Example 1, except that the content of each component in the adhesive film in Example 1 was changed as shown in Table 1 below.

[0127] Comparative Examples 4 and 5 A polarizing plate was manufactured in the same manner as in Example 1, except that the content of each component in the first liquid crystal retardation layer and the adhesive film in Example 1 was changed as shown in Table 1 below.

[0128] The adhesive films and polarizing plates of the Examples and Comparative Examples were evaluated for the physical properties shown in Table 1 below, and the results are shown in Table 1 below.

[0129] (1) Modulus of adhesive film for polarizing plates (unit: kPa) A 0.8 mm thick test piece was prepared by stacking multiple adhesive films for polarizers prepared in the examples and comparative examples. The storage modulus of the prepared test piece was measured at 1 Hz and 25°C by increasing the temperature from 0°C to 150°C at a temperature increase rate of 10°C / min using an ARES (Advanced Rheometry Expansion System, TA instrument) in a temperature sweep test (strain 5%, normal force 100N).

[0130] (2) Tackiness of adhesive film (unit: gf) The adhesive films for polarizing plates prepared in the examples and comparative examples were fixed to a glass plate, and the peel strength was measured when a 10 mm diameter aluminum circular probe was pressed against the surface of the adhesive film at 25°C under the following conditions and then peeled off. Measurement equipment: UTM (INSTRON) Pressure speed: 5mm / sec Peeling speed: 20mm / sec Load: 196g Pressurization time: 5.0 seconds Pull distance: 5mm

[0131] (3) Peeling between the first liquid crystal retardation layer and the alignment film The polarizing plates manufactured in Examples and Comparative Examples were attached to a glass plate, and the gap between the first liquid crystal retardation layer and the alignment film was widened. The upper polarizer protective film, the polarizer, and the first liquid crystal retardation layer were folded 180° under the following conditions. The presence or absence of peeling between the first liquid crystal retardation layer and the alignment film was evaluated with the naked eye. If no peeling occurred, it was evaluated as ×, and if peeling occurred, it was evaluated as ○. Evaluation equipment: UTM (INSTRON) Peeling speed: 5mm / sec Pulling distance: 80mm Sample size: 25mm x 120mm

[0132] [Table 1]

[0133] *In Table 1 above, 1) Aliphatic oligomer: Oligomer consisting of 2-ethylhexyl acrylate 2) Alicyclic and aromatic oligomers: oligomers consisting of isobornyl acrylate, tetrahydrofurfuryl acrylate, and 2-phenoxyethyl acrylate 3) Comonomer: a mixture of tetrahydrofurfuryl acrylate and 2-phenoxyethyl acrylate

[0134] As shown in Table 1, in the polarizing plates of the examples, the peeling force between the liquid crystal retardation layer and the alignment film is low, but it is clear that there is no peeling between the liquid crystal retardation layer and the alignment film.

[0135] On the other hand, in Comparative Examples 1 to 3 in which the adhesive films for polarizing plates did not satisfy the tackiness range of the present invention or did not satisfy the modulus range of the present invention, peeling occurred between the liquid crystal retardation layer and the alignment film.

[0136] Furthermore, in Comparative Examples 4 and 5, in which the peel strength between the liquid crystal retardation layer and the alignment film is high, it can be seen that there is no peeling between the liquid crystal retardation layer and the alignment film even when an adhesive film that does not satisfy the tackiness range of this invention is included.

[0137] Simple variations and modifications of the present invention can be easily implemented by those skilled in the art, and all such variations and modifications can be considered to be included within the scope of the present invention. [Explanation of symbols]

[0138] 100 Polarizer 200 protective layer 300 Lower protective layer 410 1st liquid crystal retardation layer 420 Alignment film for first liquid crystal retardation layer 500 Adhesive film for polarizing plates

Claims

1. A polarizer, a liquid crystal retardation layer and an adhesive film for a polarizing plate which are sequentially laminated on one surface of the polarizer, The adhesive film for polarizing plates has a modulus of 50 kPa to 1000 kPa at 25°C and a tackiness of 50 gf to 150 gf, The pressure-sensitive adhesive film for polarizing plates includes a cured product of a composition including a curable component and an initiator, and the curable component includes a mixture including an aliphatic oligomer, and at least one of a cycloaliphatic or heterocycloaliphatic oligomer, an aromatic oligomer, and a combination of a cycloaliphatic or heterocycloaliphatic oligomer and an aromatic oligomer, and a comonomer.

2. The polarizing plate according to claim 1 , wherein the liquid crystal retardation layer has an alignment film formed on the adhesive film for polarizing plates.

3. 3. The polarizing plate according to claim 2, wherein the peel strength between the liquid crystal retardation layer and the alignment film is 50 gf / 25 mm or less.

4. The polarizing plate according to claim 1 , wherein the mixture is contained in the curable component in an amount of 95% by weight or more.

5. 2. The polarizing plate according to claim 1, wherein the aliphatic oligomer comprises an oligomer of a (meth)acrylic monomer having a substituted or unsubstituted, linear or branched alkyl group having 4 to 10 carbon atoms.

6. 2. The polarizing plate according to claim 1, wherein the monomer for the alicyclic or heteroalicyclic oligomer comprises one or more (meth)acrylic acid esters having an alicyclic group or a heteroalicyclic group at an ester moiety.

7. The polarizing plate according to claim 1 , wherein the monomer for the aromatic oligomer comprises one or more (meth)acrylic acid esters having an aromatic group at an ester moiety.

8. 2. The polarizing plate according to claim 1, wherein the monomer for the alicyclic or heteroalicyclic and aromatic oligomer comprises one or more (meth)acrylic acid esters having an alicyclic group or a heteroalicyclic group at an ester moiety, and one or more (meth)acrylic acid esters having an aromatic group at an ester moiety.

9. The polarizing plate according to claim 6 , wherein the (meth)acrylic acid ester includes at least one of isobornyl (meth)acrylate and tetrahydrofurfuryl (meth)acrylate.

10. The polarizing plate according to claim 7 , wherein the (meth)acrylic acid ester comprises phenoxyethyl (meth)acrylate.

11. 2. The polarizing plate according to claim 1, wherein the comonomer comprises one or more (meth)acrylic acid esters having an alicyclic group or a heteroalicyclic group at an ester moiety, and one or more (meth)acrylic acid esters having an aromatic group at an ester moiety.

12. The mixture comprises: 1% by weight to 30% by weight of the aliphatic oligomer, 1% by weight to 30% by weight of one or more of the alicyclic or heteroalicyclic oligomer, aromatic oligomer, and combinations of the alicyclic or heteroalicyclic oligomer and aromatic oligomer; 2. The polarizing plate according to claim 1, wherein the comonomer is contained in an amount of 50% by weight to 90% by weight.

13. 2. The polarizing plate according to claim 1, wherein the total amount of the aliphatic oligomer and one or more of the alicyclic or heteroalicyclic oligomer, the aromatic oligomer, and the combination of the alicyclic or heteroalicyclic oligomer and the aromatic oligomer is 10% by weight or more in the mixture.

14. The polarizing plate of claim 1 , wherein the initiator is a photoinitiator.

15. The polarizing plate according to claim 1 , wherein the liquid crystal retardation layer is a discotic liquid crystal layer.

16. The polarizing plate according to claim 1 , further comprising a liquid crystal retardation layer laminated on one surface of the pressure-sensitive adhesive film for polarizing plates.

17. An adhesive film for polarizing plates, The adhesive film for polarizing plates has a modulus of 50 kPa to 1000 kPa at 25°C and a tackiness of 50 gf to 150 gf, The pressure-sensitive adhesive film for polarizing plates includes a cured product of a composition including a curable component and an initiator, and the curable component includes a mixture including an aliphatic oligomer, and one or more combinations of an alicyclic or heteroalicyclic oligomer, an aromatic oligomer, an alicyclic or heteroalicyclic oligomer, and an aromatic oligomer, and a comonomer.

18. A display device comprising the polarizing plate according to claim 1 .

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