Polarizer for light-emitting display and light-emitting display including the same

Abstract

The present invention provides a polarizer for a light-emitting display and a light-emitting display including the same. The polarizer includes: a polarizer; and a first bonding layer, a first liquid crystal retardation film, a second bonding layer, and a second liquid crystal retardation film stacked in sequence on a surface of the polarizer. The polarizer has a polarization variation ΔPE1 of 0.7% or less according to Equation 1 and a polarization variation ΔPE2 of 0.7% or less according to Equation 2.

Description

Technical Field

[0001] Embodiments of the present invention relate to a polarizer for a light-emitting display and a light-emitting display including the polarizer. Background Art

[0002] Unlike liquid crystal displays (LCDs), organic light-emitting displays (OLEDs) are self-emissive and do not require a separate polarizer. However, when an OLED includes a polarizer with a retardation film having a predetermined range of phase retardation between the polarizer and the OLED panel, it can improve screen quality by preventing reflection of external light by converting linearly polarized light received by the polarizer into circularly polarized light.

[0003] Thin liquid crystal retardation films are currently used as retardation films, improving screen quality and reducing polarizer thickness. Stacks of λ / 2 and λ / 4 retardation liquid crystal films are already used in the field, but are not limited to these. Therefore, there is a need for a bonding layer that exhibits higher peel strength than both λ / 2 and λ / 4 retardation liquid crystal films. Furthermore, with the recent development of foldable displays, there is a need for polarizers suitable for both organic light-emitting displays and foldable displays.

[0004] The background art of the present invention is disclosed in Japanese Patent Laid-Open No. 2014-032270. Summary of the Invention

[0005] Technical issues

[0006] One embodiment of the present invention is to provide a polarizer that exhibits good peel strength with respect to a liquid crystal retardation film and ensures good reliability and flexibility.

[0007] Another embodiment of the present invention is to provide a polarizer capable of minimizing or reducing the influence on polarized light passing through a first liquid crystal retardation film and a second liquid crystal retardation film.

[0008] Technical Solution

[0009] Embodiment 1: One embodiment of the present invention relates to a polarizer for a light-emitting display. The polarizer for a light-emitting display comprises:

[0010] a polarizer; and a first bonding layer, a first liquid crystal retardation film, a second bonding layer, and a second liquid crystal retardation film sequentially stacked on a surface of the polarizer,

[0011] The polarizers each have a polarization change ΔPE1 of 0.7% or less according to Equation 1 and a polarization change ΔPE2 of 0.7% or less according to Equation 2:

[0012] [Equation 1]

[0013] ΔPE1=|P1-P2|,

[0014] wherein P1 indicates the initial polarization degree (unit: %) measured on a sample having a length of 3 cm and a width of 3 cm obtained by cutting the polarizer along the MD of the polarizer and the TD of the polarizer, and

[0015] P2 indicates the degree of polarization (unit: %) measured on the sample after the sample was left at a constant temperature of 85° C. for 500 hours; and

[0016] [Equation 2]

[0017] ΔPE2=|P1-P3|,

[0018] wherein P1 indicates the initial polarization degree (unit: %) measured on a sample having a length of 3 cm and a width of 3 cm obtained by cutting the polarizer along the MD of the polarizer and the TD of the polarizer, and

[0019] P3 indicates the degree of polarization (unit: %) measured on a sample having a length of 3 cm and a width of 3 cm after the sample was left under constant temperature and humidity conditions of 60° C. and 95% for 500 hours.

[0020] Embodiment 2: In embodiment 1, the second bonding layer may be directly formed on each of the first liquid crystal retardation film and the second liquid crystal retardation film.

[0021] Example 3: In Example 1 or Example 2, the second bonding layer may be formed of a composition including an epoxy compound and a (meth)acrylate compound, wherein the (meth)acrylate compound may include a hydrophobic (meth)acrylate compound.

[0022] Example 4: In Example 3, the hydrophobic (meth)acrylate compound may include an unsubstituted linear or branched C6 to C 20 Alkyl (meth)acrylates and (meth)acrylates containing an unsubstituted aromatic group.

[0023] Example 5: In Example 4, an unsubstituted straight or branched C6 to C 20 The alkyl (meth)acrylate may include at least one of isodecyl (meth)acrylate and decyl (meth)acrylate.

[0024] Example 6: In Examples 1 to 5, the epoxy compound may include an alicyclic epoxy compound.

[0025] Example 7: In Examples 1 to 6, the epoxy compound may further include a glycidyl ether containing an aromatic group.

[0026] Example 8: In Example 7, the aromatic group-containing glycidyl ether may include at least one of phenyl glycidyl ether and resorcinol diglycidyl ether.

[0027] Example 9: In Examples 1 to 8, the composition may not contain a (meth)acrylate compound containing a hydrophilic group.

[0028] Example 10: In Examples 1 to 9, the amount of the (meth)acrylate compound may be 25 to 65 parts by weight based on 100 parts by weight of the total of the epoxy compound and the (meth)acrylate compound.

[0029] Example 11: In Examples 1 to 10, the composition may further include a photocationic initiator and a photoradical initiator.

[0030] Example 12: In Examples 1 to 11, the composition may include: 35 to 90 parts by weight of an epoxy compound; 10 to 65 parts by weight of a (meth)acrylate compound; 1 to 10 parts by weight of a photocationic initiator based on a total of 100 parts by weight of the epoxy compound and the (meth)acrylate compound; and 0.5 to 10 parts by weight of a photoradical initiator based on a total of 100 parts by weight of the epoxy compound and the (meth)acrylate compound.

[0031] Embodiment 13: In Embodiments 1 to 12, the second bonding layer may have a glass transition temperature of 70°C to 110°C.

[0032] Example 14: In Examples 1 to 13, the first bonding layer may be formed of a composition including an epoxy compound and a (meth)acrylate compound, wherein the (meth)acrylate compound may include a hydrophobic (meth)acrylate compound.

[0033] Example 15: In Example 14, the composition may not contain a (meth)acrylate compound containing a hydrophilic group.

[0034] Embodiment 16: In Embodiments 1 to 15, the first bonding layer may have a glass transition temperature of 70°C to 110°C.

[0035] Example 17: In Examples 1 to 16, each of the first and second liquid crystal retardation films may be formed of a composition including at least one of an alicyclic group-containing (meth)acrylic liquid crystal compound and an aromatic group-containing (meth)acrylic liquid crystal compound.

[0036] Example 18: In Examples 1 to 17, the polarizer may further include a protective layer on the other surface of the polarizer.

[0037] Another embodiment of the present invention relates to a light-emitting display.

[0038] Example 19: A light-emitting display may include the polarizer for a light-emitting display according to the present invention.

[0039] Embodiment 20: In Embodiment 19, the light-emitting display may include a foldable light-emitting display.

[0040] Beneficial effects

[0041] The present invention provides a polarizer that exhibits good peel strength relative to a liquid crystal retardation film and ensures good reliability and flexibility.

[0042] The present invention provides a polarizer capable of minimizing the influence on polarized light passing through a first liquid crystal retardation film and a second liquid crystal retardation film. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 FIG. 4 is a cross-sectional view of a polarizer for a light-emitting display according to an embodiment of the present invention.

[0044] Figure 2 FIG. 4 is a cross-sectional view of a polarizer for a light-emitting display according to another embodiment of the present invention. DETAILED DESCRIPTION

[0045] Embodiments of the present invention will be described in detail with reference to the accompanying drawings to provide a thorough understanding of the present invention to those skilled in the art. It should be understood that the present invention can be implemented in various ways and is not limited to the following embodiments. In the accompanying drawings, portions not relevant to the description may be omitted for clarity. Throughout this specification, identical components will be represented by the same reference numerals. It should be understood that for ease of description, the lengths, thicknesses, and the like of various components may be exaggerated or not illustrated to scale in the accompanying drawings, and the present invention is not limited thereto.

[0046] In this document, spatially related terms such as "upper" and "lower" are defined with reference to the accompanying drawings. Thus, for example, it will be understood that the term "upper surface" can be used interchangeably with the term "lower surface."

[0047] Herein, "in-plane retardation (Re)" is a value measured at a wavelength of 550 nanometers and is expressed by Equation A:

[0048] [Equation A]

[0049] Re=(nx-ny)×d

[0050] wherein nx and ny are the refractive indices on the slow axis and fast axis of the liquid crystal retardation film at a wavelength of 550 nm, respectively, and d is the thickness of the liquid crystal retardation film (unit: nm).

[0051] As used herein, the term “light-emitting device” includes organic or inorganic light-emitting devices and may refer to light-emitting diodes (LEDs), organic light-emitting diodes (OLEDs), quantum dot light-emitting diodes (QLEDs), devices containing light-emitting substances such as phosphors, and the like.

[0052] Herein, “X to Y” means “X or greater than X to Y or less than Y” or “X ≥ and ≤ Y”.

[0053] Based on the following findings, in a polarizer for a light-emitting display comprising a polarizer, a first bonding layer, a first liquid crystal retardation film, a second bonding layer and a second liquid crystal retardation film stacked in the stated order, the inventors improved the peel strength of the second bonding layer relative to each of the first liquid crystal retardation film and the second liquid crystal retardation, achieved good flexibility and reliability of the polarizer under high temperature conditions and minimized the influence on reflected light by the liquid crystal retardation film to complete the present invention.

[0054] The present invention can ensure favorable effects by using a specific composition of a first bonding layer for bonding between a first liquid crystal retardation film and a polarizer and a specific composition of a second bonding layer for bonding the first liquid crystal retardation film to a second liquid crystal retardation film in several bonding layers or adhesive layers in a polarizer for a light-emitting display.

[0055] In the following, reference will be made to Figure 1 A polarizer for a light-emitting display (hereinafter, "polarizer") according to the present invention is described.

[0056] refer to Figure 1 The polarizer may include a polarizer 10 ; and a first bonding layer 50 , a first liquid crystal retardation film 20 , a second bonding layer 30 , and a second liquid crystal retardation film 40 sequentially formed on one surface of the polarizer 10 .

[0057] Second bonding layer

[0058] The second bonding layer 30 may be formed directly on each of the first liquid crystal retardation film 20 and the second liquid crystal retardation film 40. Herein, the expression "formed directly on..." means that, except for the second bonding layer 30, another bonding layer, another adhesive layer, or another adhesive layer / bonding layer is not interposed between the first liquid crystal retardation film 20 and the second liquid crystal retardation film 40.

[0059] The second bonding layer 30 has a higher peel strength relative to each of the first liquid crystal retardation film 20 and the second liquid crystal retardation film 40, and thus prevents separation between the first liquid crystal retardation film and the second liquid crystal retardation film, thereby maintaining the shape of the polarizer and preventing separation or bubbling under reliability test conditions (especially under high temperature / high humidity).

[0060] For each of the first and second liquid crystal retardation films, the second bonding layer may have a peel strength of 100 gf / 25 mm or greater, for example, 100 gf / 25 mm to 3000 gf / 25 mm. Within this range, it is possible to maintain the shape of the polarizer without separating the first and second liquid crystal retardation films at room temperature.

[0061] In evaluating the flexibility of the polarizer, described in further detail below, the second bonding layer 30 prevents cracks or creases from forming on each of the first and second liquid crystal retardation films, thereby improving the flexibility of the polarizer. Consequently, the polarizer can enhance screen quality when used in a foldable light-emitting display.

[0062] The "flexibility evaluation" of a polarizer (a polarizer comprising a polarizer protective layer, a polarizer, a first bonding layer, a first retardation film, a second bonding layer, and a second retardation film stacked in the order listed) can be measured according to IEC-62715. Specifically, 80-micrometer-thick polyethylene terephthalate (PET) films are attached to both surfaces of the polarizer via an acrylic adhesive. The polarizer is then cut into a size of 6 cm x 4 cm (length x width, polarizer MD x polarizer TD) to prepare a sample. Next, the sample was mounted on a flexibility tester so that the PET film closest to the polarizer was placed inside the polarizer during the flexibility test. The sample was then repeatedly bent at 25°C under conditions of a 5mm bend radius, a bending speed of 30 times / minute, and a bending angle of 180°. The flexibility was evaluated by counting the number of bends required until a first crack or crease appeared in the first and / or second liquid crystal retardation films. A polarizer with a bending frequency of 100,000 or more demonstrated excellent screen quality, even when used in foldable light-emitting displays.

[0063] The second bonding layer 30 may be formed between the first liquid crystal retardation film 20 and the second liquid crystal retardation film 40, thereby reducing the effect on the polarization of linearly polarized light that has passed through the polarizer when it is converted into circularly polarized light by sequentially passing through the first liquid crystal retardation film 20, the second bonding layer 30, and the second liquid crystal retardation film 40. Therefore, the second bonding layer can improve the circular polarization of the first and second liquid crystal retardation films.

[0064] The second bonding layer 30 improves the reliability of the polarizer even under high temperature and / or high temperature / high humidity conditions. The first liquid crystal retardation film bonded to one surface of the polarizer is relatively thin and cannot adequately suppress changes in polarization when the polarizer is maintained under high temperature and / or high temperature / high humidity conditions. In contrast, the second bonding layer is formed on the other surface of the first liquid crystal retardation film, that is, on the surface of the first liquid crystal retardation film not bonded to the polarizer, thereby improving reliability by suppressing changes in polarization.

[0065] For example, according to Equation 1 or Equation 2, the polarizer according to the present invention may have a polarization change ΔPE1 or a polarization change ΔPE2 of 0.7% or less (e.g., 0 to 0.7%), respectively. For a more specific example, according to Equation 1 or Equation 2, the polarizer according to the present invention may have a polarization change ΔPE1 or a polarization change ΔPE2 of 0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, or 0.7%, respectively:

[0066] [Equation 1]

[0067] ΔPE1=|P1-P2|

[0068] Wherein P1 indicates the initial polarization degree (unit: %) measured on a sample obtained by cutting the polarizer into a size of 3 cm × 3 cm (length × width, MD of the polarizer × TD of the polarizer) and

[0069] P2 indicates the degree of polarization (unit: %) measured on the sample after the sample was left at a constant temperature of 85° C. for 500 hours; and

[0070] [Equation 2]

[0071] ΔPE2=|P1-P3|

[0072] Wherein P1 indicates the initial polarization degree (unit: %) measured on a sample obtained by cutting the polarizer into a size of 3 cm × 3 cm (length × width, MD of the polarizer × TD of the polarizer) and

[0073] P3 indicates the degree of polarization (unit: %) measured on the sample after the sample was left under constant temperature / humidity conditions of 60° C. and 95% for 500 hours.

[0074] The second bonding layer 30 may have a glass transition temperature of 70°C to 110°C. Within this range, the second bonding layer can have good peel strength relative to the first and second liquid crystal retardation films, and can impart excellent reliability and flexibility to the polarizer. Preferably, the second bonding layer 30 has a glass transition temperature greater than 70°C and 110°C, or less than 110°C, more preferably between 85°C and 100°C.

[0075] The second bonding layer 30 may be formed of a bonding composition including an epoxy compound and a hydrophobic (meth)acrylate compound, which will be described in detail below.

[0076] Next, the bonding composition will be described in more detail.

[0077] Epoxides

[0078] The epoxy compound may include an alicyclic epoxy compound.

[0079] As used herein, the term "alicyclic epoxy compound" may refer to a compound containing an epoxidized alicyclic group. For example, the alicyclic epoxy compound is a difunctional alicyclic epoxy compound and may include at least one of the following: 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate, 3,4-epoxy-6-methylcyclohexylmethyl-3',4'-epoxy-6'-methylcyclohexanecarboxylate, bis(3,4-epoxy-6-methylcyclohexyl)adipate, dicyclohexyl diepoxy (3,4,3',4'-diepoxy-bicyclohexane), and 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate-modified ε-caprolactone, but is not limited thereto.

[0080] The amount of the alicyclic epoxy compound may be 40 to 90 parts by weight, for example, 50 to 90 parts by weight, or 50 to 80 parts by weight, relative to a total of 100 parts by weight of the epoxy compound and the (meth)acrylate compound. Within this range, excellent bonding between the liquid crystal retardation films can be obtained without reducing wettability due to an increase in the viscosity of the composition. In addition, brittleness of the bonding layer caused by an excessive increase in the modulus does not occur, so there are no problems with the crack resistance and cutting characteristics of the polarizer.

[0081] In one embodiment, the amount of the alicyclic epoxy compound relative to 100 parts by weight of the total epoxy compound and the (meth)acrylate compound may be 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, 80 parts by weight, 81 parts by weight, 82 parts by weight, 83 parts by weight, 84 parts by weight, 85 parts by weight, 86 parts by weight, 87 parts by weight, 88 parts by weight, 89 parts by weight, 90 parts by weight, 91 parts by weight, 92 parts by weight, 93 parts by weight, 94 parts by weight, 95 parts by weight, 96 parts by weight, 97 parts by weight, 98 parts by weight, 99 parts by weight, 100 parts by weight, 1 parts by weight, 10 parts by weight, 10 parts by weight, 10 parts by weight, 10 parts by weight, 10 parts by weight, 10 parts by weight, 10 parts by weight, 10 parts by weight, 10 parts by weight, 10 parts by weight, 10 parts by weight, 10 parts by weight, 10 parts by weight, 10 parts by weight, 10 parts by weight, 10 parts by weight, 10 parts by weight, 10 parts by weight, 10 parts by weight, 10 parts by weight, 10 parts by weight, 10 parts by weight, 10 parts by weight, 10 parts by weight, 10 parts by weight, 10 parts by weight, 10 parts by weight,

[0082] The epoxy compound may also include glycidyl ethers containing aromatic groups.

[0083] The aromatic glycidyl ether can provide a post-curing effect by a dark reaction and improve the bonding with the liquid crystal retardation film. In one embodiment, the above effects can be further improved by including an alicyclic epoxy compound and the aromatic glycidyl ether together.

[0084] The aromatic glycidyl ether may include a compound containing one or more glycidyl ether groups. "Glycidyl ether group" may refer to a moiety of Formula 1:

[0085] [Formula 1]

[0086]

[0087] * is the linking site

[0088] The aromatic group-containing glycidyl ether may be a monofunctional glycidyl ether and may include an aromatic group and one glycidyl ether group. For example, the monofunctional glycidyl ether may include phenyl glycidyl ether, but is not limited thereto.

[0089] The aromatic-group-containing glycidyl ether may be a difunctional diglycidyl ether and may include an aromatic group and two glycidyl ether groups. For example, the difunctional diglycidyl ether may include at least one of resorcinol diglycidyl ether and a 4,4'-(1-methylethylidene)bisphenol polymer with (chloromethyl)oxirane.

[0090] In one embodiment, the aromatic group-containing glycidyl ether may include only monofunctional glycidyl ether.

[0091] In another embodiment, the aromatic group-containing glycidyl ether may include only difunctional diglycidyl ether.

[0092] In another embodiment, the aromatic group-containing glycidyl ether may include a mixture of monofunctional glycidyl ether and difunctional diglycidyl ether. For example, the aromatic group-containing glycidyl ether may include at least one of phenyl glycidyl ether and resorcinol diglycidyl ether.

[0093] The amount of the aromatic glycidyl ether can be 0 to 10 parts by weight, specifically 0.1 to 10 parts by weight, and more specifically 1 to 10 parts by weight, relative to a total of 100 parts by weight of the epoxy compound and the (meth)acrylate compound. Within this range, the initial curing speed is not slowed down, so that problems such as a decrease in initial bonding strength do not occur, and reliability and peel strength may not be reduced even under high temperature and high humidity. In one embodiment, the amount of the aromatic glycidyl ether can be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 parts by weight.

[0094] Relative to 100 parts by weight of the total of the epoxy compound and the (meth)acrylate compound, the amount of the epoxy compound may be 35 parts by weight to 90 parts by weight, specifically 35 parts by weight to 85 parts by weight, 35 parts by weight to 75 parts by weight. Within this range, the bonding layer can obtain improved crack resistance due to the increase in its glass transition temperature. In one embodiment, the amount of the epoxy compound may be 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, 60 parts by weight, 61 parts by weight, 83 parts by weight, 84 parts by weight, 85 parts by weight, 86 parts by weight, 87 parts by weight, 88 parts by weight, 89 parts by weight or 90 parts by weight.

[0095] (Meth)acrylate compounds

[0096] The (meth)acrylate compound can be polymerized by a photoradical initiator initiated by light energy and can stably react by light energy without being inhibited by moisture.

[0097] The composition may include a (meth)acrylate compound that does not have any hydrophilic groups (such as hydroxyl groups, carboxyl groups, and the like). Herein, a (meth)acrylate compound that does not have any hydrophilic groups is referred to as a "hydrophobic (meth)acrylate compound."

[0098] By including the hydrophobic (meth)acrylate compound as the (meth)acrylate compound, the composition can improve the reliability of the polarizer, especially after the polarizer is placed under high temperature and high humidity for a long time.

[0099] In one embodiment, the composition may not contain a (meth)acrylate compound containing a hydrophilic group.

[0100] The hydrophobic (meth)acrylate compound may include an unsubstituted linear or branched C6 to C 20(Meth)acrylates containing an alkyl group and (meth)acrylates containing an unsubstituted aromatic group. If any of these are not included, the glass transition temperature of the bonding layer may exceed 110°C, and the second bonding layer may not meet the appropriate glass transition temperature range, resulting in reduced peel strength relative to the liquid crystal retardation film or reduced flexibility or reliability of the polarizer. In one embodiment, the composition may include unsubstituted linear or branched C6 to C 20 Both the alkyl (meth)acrylate and the aromatic group-containing (meth)acrylate ensure the effects of the present invention. Here, the "number of carbon atoms" of the alkyl group is a value excluding the number of carbon atoms contained in the (meth)acrylate group.

[0101] Contains unsubstituted straight or branched C6 to C 20 The alkyl (meth)acrylate may include at least one of the following: hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, and dodecyl (meth)acrylate. Preferably, the alkyl (meth)acrylate contains an unsubstituted linear or branched C6 to C 20 The alkyl (meth)acrylate may contain unsubstituted branched C6 to C 20 Alkyl (meth) acrylate, more preferably containing unsubstituted branched C8 to C 12 Alkyl (meth)acrylate, most preferably at least one of isodecyl (meth)acrylate and decyl (meth)acrylate.

[0102] With respect to 100 parts by weight of the total of the epoxy compound and the (meth)acrylate compound, the unsubstituted straight-chain or branched C6 to C 20 The amount of the alkyl (meth)acrylate may be 1 to 30 parts by weight, for example, 5 to 20 parts by weight. Within this range, good peel strength of the bonding layer and reliability of the polarizer can be obtained even under high temperature and high humidity conditions. In one embodiment, the unsubstituted linear or branched C6 to C 20 The amount of the alkyl (meth)acrylate may be 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 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, or 30 parts by weight.

[0103] The (meth)acrylate containing an aromatic group is a monofunctional (meth)acrylate or a multifunctional (meth)acrylate, and may include, for example, a C1 to C5 alkyl group, a C1 to C5 alkylene group, or a C1 to C5 alkylene oxide group. 20 (Meth)acrylates containing an aromatic group (eg, a phenoxy group). Preferably, the (meth)acrylate containing an aromatic group comprises phenol ethoxylated (meth)acrylate.

[0104] The amount of the (meth)acrylate containing an aromatic group can be 1 to 20 parts by weight, for example, 5 to 20 parts by weight, relative to a total of 100 parts by weight of the epoxy compound and the (meth)acrylate compound. Within this range, the composition allows the bonding layer to have a glass transition temperature according to the present invention and can improve the initial bonding strength of the bonding layer. In one embodiment, the amount of the (meth)acrylate containing an aromatic group can be 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 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, or 20 parts by weight.

[0105] The amount of the (meth)acrylate compound (preferably a hydrophobic (meth)acrylate compound) may be 10 to 65 parts by weight, for example, 15 to 65 parts by weight, or 25 to 65 parts by weight, relative to a total of 100 parts by weight of the epoxy compound and the (meth)acrylate compound. Within this range, even if the bonding composition shrinks during curing, the bonding layer can obtain good bonding strength and maintain good adhesion to the surface of the liquid crystal retardation film. In one embodiment, the amount of the hydrophobic (meth)acrylate compound may be 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, or 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, 60 parts by weight, 61 parts by weight, 62 parts by weight, 63 parts by weight, 64 parts by weight or 65 parts by weight.

[0106] initiator

[0107] The initiator may comprise a mixture of a photocationic initiator and a photoradical initiator.

[0108] The photocationic initiator may include a typical photocationic initiator capable of performing a photocuring reaction.

[0109] The photocationic initiator may comprise an onium salt of an onium ion comprising a cation and an anion. Examples of onium ions may include diaryliodoniums 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; triarylsulfoniums such as triphenylsulfonium and diphenyl-4-thiophenoxyphenylsulfonium; diphenyl-4(phenylthio)phenylsulfonium, bis[4-(diphenyldihydrosulfanyl)phenyl]sulfide, bis[4-(bis(4-(2-hydroxyethyl)phenyl)dihydrosulfanyl)-phenyl]sulfide, (η5-2,4-cyclopentadien-1-yl)[(1,2,3,4,5,6-η)-(1-methylethyl)phenyl]iron(1+), and the like. Examples of anions may include tetrafluoroborate (BF4 - ), hexafluorophosphate (PF6 - ), hexafluoroantimonate (SbF6 - ), hexafluoroarsenate (AsF6 - ), hexachloroantimonate (SbCl6 - ) and the like.

[0110] The amount of the photocationic initiator may be 1 to 10 parts by weight, for example 2 to 10 parts by weight, relative to a total of 100 parts by weight of the epoxy compound and the (meth)acrylate compound. Within this range, the composition for the bonding layer can be sufficiently cured without suffering from a decrease in peel strength, leaching of the photocationic initiator, or the like. In one embodiment, the amount of the photocationic initiator may be 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, or 10 parts by weight.

[0111] The photoradical initiator can generate a small amount of free radicals after being irradiated with light to accelerate the curing reaction. The photoradical initiator can include phenyl ketone, phosphorus, triazine, acetophenone, benzophenone, thioxanthone, benzoin, oxime compounds and mixtures thereof. In some embodiments, the photoradical initiator can include phenyl ketone compounds or mixtures thereof.

[0112] The amount of the photoradical initiator can be 0.5 to 10 parts by weight, for example, 0.5 to 6 parts by weight, relative to a total of 100 parts by weight of the epoxy compound and the (meth)acrylate compound. Within this range, the (meth)acrylate compound can be sufficiently cured under conditions of light intensity for processing, and the reactivity of the photocationic initiator can be increased. In one embodiment, the amount of the photoradical initiator can be 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 parts by weight.

[0113] The composition for the second bonding layer can be prepared by mixing an epoxy compound, a (meth)acrylate compound, a photocationic initiator, and a photoradical initiator. The composition for the second bonding layer can be solvent-free or can further contain a solvent to improve applicability (coatability).

[0114] Within the scope of not reducing the effect of the present invention, the composition for the second bonding layer may also include antioxidants, UV absorbers, additives for imparting conductivity (such as ion conductors and conductive metal oxide particles), additives for imparting light diffusivity, viscosity regulators and the like.

[0115] The composition for the second bonding layer may be photocured by irradiating light having a UVA wavelength at 50 to 400 mJ / cm2, preferably 60 to 300 mJ / cm2 to form the second bonding layer.

[0116] The second bonding layer 30 may have a thickness of 0.1 μm to 30 μm, for example, 1 μm to 10 μm. Within this range, the second bonding layer may have a suitable thickness to ensure peel strength relative to each of the first and second liquid crystal retardation films and may be used in polarizers.

[0117] A first liquid crystal retardation film and a second liquid crystal retardation film

[0118] The first and second liquid crystal retardation films 20 and 40 may improve screen quality by preventing reflection of external light through circularly polarized light of linearly polarized light having passed through a polarizer.

[0119] In one embodiment, the in-plane retardation (Re) of the first liquid crystal retardation film at a wavelength of 550 nanometers may be 100 nanometers to 220 nanometers, specifically 100 nanometers to 180 nanometers. For example, the first liquid crystal retardation film may be a λ / 4 retardation film. Here, the in-plane retardation (Re) of the second liquid crystal retardation film at a wavelength of 550 nanometers may be 225 nanometers to 350 nanometers, specifically 225 nanometers to 300 nanometers. For example, the second liquid crystal retardation film may be a λ / 2 retardation film.

[0120] In another embodiment, the in-plane retardation (Re) of the first liquid crystal retardation film at a wavelength of 550 nanometers may be 225 nanometers to 350 nanometers, specifically 225 nanometers to 300 nanometers. For example, the first liquid crystal retardation film may be a λ / 2 retardation film. Here, the in-plane retardation (Re) of the second liquid crystal retardation film at a wavelength of 550 nanometers may be 100 nanometers to 220 nanometers, specifically 100 nanometers to 180 nanometers. For example, the second liquid crystal retardation film may be a λ / 4 retardation film.

[0121] The first and second liquid crystal retardation films can have the same or different thicknesses. For example, the thickness of each of the first and second liquid crystal retardation films can be 0.1 to 30 microns, specifically 1 to 10 microns. Within this thickness range, the polarizer can have a relatively thin thickness while still achieving the target retardation value.

[0122] In one embodiment, each of the first and second liquid crystal retardation films may be a liquid crystal retardation layer consisting of a single layer. Since each of the first and second liquid crystal retardation films is composed of a liquid crystal retardation layer, the liquid crystal retardation layer is composed of a single layer, thereby significantly reducing the thickness of the polarizer.

[0123] The liquid crystal retardation layer may be formed from a composition including at least one of an alicyclic group-containing (meth)acrylic liquid crystal compound or an aromatic group-containing (meth)acrylic liquid crystal compound. The liquid crystal retardation layer may further contain additives such as a leveling agent, a polymerization initiator, an alignment aid, a thermal stabilizer, a lubricant, a plasticizer, an antistatic agent, and the like.

[0124] In another embodiment, each of the first and second liquid crystal retardation films may include a base film and a liquid crystal retardation layer formed on the base film. Each of the first and second liquid crystal retardation films may be formed by coating a composition for forming a liquid crystal retardation layer on the base film and then curing the composition.

[0125] polarizer

[0126] The polarizer 10 is formed on the first liquid crystal retardation film to polarize internal light or external light. For the first liquid crystal retardation film composed of a liquid crystal retardation layer, a composition for forming the liquid crystal retardation layer is applied to the polarizer and then cured. Thus, the first liquid crystal retardation film can be formed directly on the polarizer.

[0127] The polarizer 10 may comprise a polyvinyl alcohol (PVA) polarizer formed by dyeing a PVA film with iodine or the like. For example, a PVA polarizer can be manufactured by dyeing the PVA film with iodine or a dichroic dye and then stretching the dyed film in a particular direction. Specifically, the PVA polarizer is manufactured by swelling, dyeing, and stretching. The methods for each of these processes are well known to those skilled in the art. The polarizer thickness can range from 1 micron to 50 microns. Within this range, the polarizer can be used in light-emitting displays.

[0128] First bonding layer

[0129] The first bonding layer 50 is formed between the polarizer 10 and the first liquid crystal retardation film 20 to bond the polarizer to the first liquid crystal retardation film. Here, the first bonding layer may be formed of the composition used for the second bonding layer described above.

[0130] The thickness of the first bonding layer 50 may be 0.1 micrometer to 30 micrometers, for example, 1 micrometer to 10 micrometers. Within this thickness range, the first bonding layer can be used in a light-emitting display.

[0131] The first bonding layer 50 may have a glass transition temperature that is equal to or different from that of the second bonding layer. In one embodiment, the first bonding layer 50 may have a glass transition temperature of 70°C to 110°C. Within this range, the first bonding layer can have good peel strength relative to each of the first liquid crystal retardation film and the polarizer, and can provide the polarizer with excellent reliability and flexibility. Preferably, the first bonding layer 50 may have a glass transition temperature greater than 70°C and 100°C, or less than 100°C, more preferably 85°C to 100°C.

[0132] although Figure 1 Not shown, but an adhesive film is further formed on the lower surface of the second liquid crystal delay film on which the bonding layer is not formed, that is, on the surface of the second liquid crystal delay film, to attach the polarizer to the light-emitting device (e.g., an organic light-emitting device panel).

[0133] Reference again Figure 1 The polarizer includes a first bonding layer. In one embodiment, when the first liquid crystal retardation film is a liquid crystal retardation layer, the first liquid crystal retardation film can be directly formed on the polarizer without the first bonding layer.

[0134] Next, refer to Figure 2A polarizer according to another embodiment will be described.

[0135] refer to Figure 2 The polarizer according to this embodiment includes a polarizer 10; a protective layer 60 formed on the upper surface of the polarizer 10; and a first bonding layer 50, a first liquid crystal retardation film 20, a second bonding layer 30, and a second liquid crystal retardation film 40 formed in sequence on the lower surface of the polarizer 10. In addition to the protective layer 60 further formed on the upper surface of the polarizer 10, the polarizer according to this embodiment is Figure 1 The polarizers are essentially the same.

[0136] A protective layer 60 is formed on the upper surface of the polarizer to support the polarizer. Furthermore, when the first liquid crystal retardation film is formed on the lower surface of the polarizer, the protective layer formed on the upper surface of the polarizer allows the first liquid crystal retardation film to be formed directly on the polarizer without a first bonding layer. The protective layer may include at least one of an optically transparent protective film and an optically transparent protective coating.

[0137] When the protective layer is a protective film type, the protective layer 60 may include a protective film formed from an optically transparent resin. The protective film may be formed by melting and extruding the resin. The resin may be further stretched as needed. The optically transparent resin may include at least one selected from the following: a cellulose ester resin including triacetyl cellulose, a cyclic polyolefin resin including a cyclic olefin polymer (COP), a polycarbonate resin, a polyester resin including polyethylene terephthalate (PET), a polyethersulfone resin, a polysulfone resin, a polyamide resin, a polyimide resin, a non-cyclic polyolefin resin, a polyacrylate resin including poly(methyl methacrylate), a polyvinyl alcohol resin, a polyvinyl chloride resin, and a polyvinylidene chloride resin. Preferably, the protective film is a film formed from a cyclic polyolefin resin including a cyclic olefin polymer (COP).

[0138] When the protective layer is a protective coating type, the protective layer can improve adhesion to the polarizer, transparency, mechanical strength, thermal stability, moisture resistance, and durability. In one embodiment, the protective coating for the protective layer can be formed of an actinic radiation curable resin composition containing an actinic radiation curable compound and a polymerization initiator.

[0139] The actinic radiation curable compound may include at least one 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, or an oxetane compound having at least one oxetane ring. The radically polymerizable curable compound may be a (meth)acrylic compound having at least one (meth)acryloyloxy group.

[0140] The thickness of the protective layer 60 can be 5 to 200 microns, specifically 30 to 120 microns. A protective film-type protective layer can have a thickness of 30 to 100 microns, and a protective coating-type protective layer can have a thickness of 5 to 50 microns. Within this thickness range, the protective layer can be used in light-emitting displays.

[0141] although Figure 2 Although not shown in the figures, the polarizer may further include a functional coating layer on the upper surface of the protective layer 60, such as a hard coating layer, an anti-fingerprint layer, and an anti-reflection layer.

[0142] although Figure 2 Although not shown, when the protective layer 60 is a protective film type, the polarizer may further include a third bonding layer between the protective layer and the polarizer. The third bonding layer may be formed of a typical bonding agent used for polarizing plates (e.g., a water-based bonding agent containing a polyvinyl alcohol resin as an adhesive resin, a light-curable bonding agent, and a pressure-sensitive bonding agent).

[0143] Next, another embodiment of the polarizer of the present invention will be described.

[0144] According to another embodiment, in addition to at least one of the first bonding layer 50 and the second bonding layer 30 being formed of a composition in which a silane coupling agent is further added to the bonding composition described above, the polarizer and Figure 1 The above-described embodiments shown in FIG. 1 are substantially the same.

[0145] When at least one of the first bonding layer 50 and the second bonding layer 30 is formed of a composition further including a silane coupling agent, the reliability of the polarizer under high temperature and / or high temperature and high humidity conditions can be further improved.

[0146] The silane coupling agent may be a siloxane group (-*Si(OR 1 ) n (R 2 ) 3-n , wherein n is an integer from 1 to 3, R 1 is a C1 to C5 alkyl group, R 2The silane coupling agent may be a compound containing a hydroxyl group, a halogen group, or a C1 to C4 alkyl group and may include any suitable silane coupling agent available in the art. In one embodiment, the silane coupling agent may include at least one of the following: an epoxy group-containing silane coupling agent, such as 3-glycidoxypropyltrimethoxysilane, glycidoxypropylmethyldimethoxysilane, etc.; an unsaturated group-containing silane coupling agent, such as vinyltrimethoxysilane, etc.; a mercapto group-containing silane coupling agent, such as mercaptopropyltrimethoxysilane, etc.

[0147] The amount of the silane coupling agent may be 0.01 to 10 parts by weight, for example, 0.1 to 5 parts by weight, relative to a total of 100 parts by weight of the epoxy compound and the (meth)acrylate compound. Within this range, the polarizer may have improved reliability under high temperature and high humidity conditions. In one embodiment, the amount of the silane coupling agent may be 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 parts by weight.

[0148] A light-emitting display according to one embodiment may include a polarizer according to the present invention. For example, the light-emitting display may include an organic light-emitting display, but is not limited thereto. While the light-emitting display according to the present invention may be applicable to non-foldable light-emitting displays, the light-emitting display may exhibit good flexibility when used in a foldable light-emitting display.

[0149] Invention Mode

[0150] Next, the present invention will be described in more detail with reference to some examples. However, it should be noted that these examples are provided for illustration only and should not be interpreted as limiting the present invention in any way.

[0151] Example 1

[0152] A polyvinyl alcohol film (99.5% saponification degree, 2,000 degree of polymerization, 60 μm thickness) was dyed by immersing it in a 0.3% iodine aqueous solution and then stretched to 5.0 times in the machine direction (MD). The stretched polyvinyl alcohol film was then immersed in a 3% boric acid solution and a 2% potassium iodide aqueous solution for color correction and then dried at 50°C for 4 minutes to prepare a polarizer (23 μm thickness).

[0153] As the first liquid crystal retardation film, a liquid crystal coated retardation film (Fuji Film Co., Ltd. QL AA 328, cyclic (aromatic) acrylic liquid crystal retardation layer, Re: 234 nm at a wavelength of 550 nm) was used. Both surfaces of the liquid crystal coated retardation film were subjected to a corona treatment of 250 mJ / cm².

[0154] As the second liquid crystal retardation film, a liquid crystal coated retardation film (Fujifilm Corporation, QA AB 318, cyclic (aromatic) acrylic liquid crystal retardation layer, Re: 116 nm at a wavelength of 550 nm) was used. Both surfaces of the liquid crystal coated retardation film were subjected to a corona treatment of 250 mJ / cm².

[0155] Step (1): Preparation of pre-polarizer

[0156] A pre-polarizer was prepared by laminating a protective layer, a composition for a bonding layer (third bonding layer), a polarizer, a composition for a bonding layer (first bonding layer), and an unsaponified triacetylcellulose (TAC) film in this order under the conditions of 22° C. to 25° C. and 20% to 60% RH.

[0157] As the protective layer, a cycloolefin polymer (COP) resin film (thickness: 30 μm, transparent protective film) was used. One surface of the cycloolefin resin film was subjected to a corona treatment at 250 mJ / cm 2 .

[0158] The third bonding layer was formed from a composition comprising a PVA-based aqueous bonding agent containing 100 parts by weight of water, 3 parts by weight of a polyvinyl alcohol resin (product name: Z320, Nippon Synthetic Chemical Industry Co., Ltd.), and 3 parts by weight of glyoxal (TCL). The third bonding layer composition was applied to one surface of the protective layer, and then a polarizer was laminated thereon. The composition was then thermally cured in a drying oven at 50°C for 1 minute and at 85°C for 2 minutes to form the third bonding layer.

[0159] Next, a composition for a first bonding layer was applied to the other surface of the polarizer, and then an unsaponified triacetyl cellulose (TAC) film was laminated thereon. The composition for the first bonding layer was prepared by mixing an epoxy compound, a (meth)acrylate compound, and an initiator according to the composition shown in Table 1.

[0160] Step (2): preparing a laminate of the first liquid crystal retardation film-the second bonding layer-the second liquid crystal retardation film

[0161] A laminate of the first liquid crystal retardation film-the second bonding layer-the second liquid crystal retardation film was prepared under the conditions of 22° C. to 25° C. and 20% RH to 60% RH.

[0162] A composition for a second bonding layer prepared by mixing an epoxy compound, a (meth)acrylate compound, and an initiator according to the composition shown in Table 1 was applied to one side of the first liquid crystal retardation film, and then the second liquid crystal retardation film was stacked thereon, and then the first liquid crystal retardation film was exposed to obtain a laminate.

[0163] Step (3): Preparation of polarizer

[0164] The polarizer was prepared under conditions of 22° C. to 25° C. and 20% RH to 60% RH.

[0165] The unsaponified TAC film was separated and removed from the pre-polarizer prepared in step (1). The first bonding layer of the pre-polarizer was laminated to contact the first liquid crystal retardation film of the laminate having the structure of the first liquid crystal retardation film-second bonding layer-second liquid crystal retardation film prepared in step (2), and then the second liquid crystal retardation film was exposed using a metal halide lamp (LICHTZEN Co., Ltd.) to obtain a polarizer in which a protective layer, a third bonding layer (thickness: 0.1 μm, PVA-based water-based bonding layer), a polarizer, a first bonding layer (thickness: 3 μm, UV-curable bonding layer of the present invention), a first liquid crystal retardation film (Re: 234 nm), a second bonding layer (thickness: 3 μm, UV-curable bonding layer of the present invention), and a second liquid crystal retardation film (Re: 116 nm) were stacked in sequence.

[0166] For the measurement of the peel strength, UV irradiation was performed using a light shielding member attached to a portion of the lower surface of the second liquid crystal retardation film.

[0167] Examples 2 to 6

[0168] Each polarizer was prepared in the same manner as in Example 1, except that the components and / or contents of the compositions for the second bonding layer and the first bonding layer were changed as shown in Table 1.

[0169] Comparative Example 1 to Comparative Example 4

[0170] Each polarizer was prepared in the same manner as in Example 1, except that the components and / or contents of the compositions for the second bonding layer and the first bonding layer were changed as shown in Table 1.

[0171] The components and contents (unit: parts by weight) of the compositions for the first and second bonding layers used in Examples and Comparative Examples are shown in Table 1. Each component in Table 1 is expressed as a solid content excluding a solvent. In Table 1, "-" means that the component is not included.

[0172] Glass transition temperature (Tg) of the second bonding layer (or first bonding layer) (unit: °C):

[0173] The composition for the second bonding layer was applied to a predetermined thickness on a processing film (PET film) and cured via UV radiation, thereby preparing a sample having a second bonding layer thickness of 5 to 10 microns. Tan δ values ​​for the prepared samples were measured using a dynamic mechanical analyzer (DMA) while increasing the temperature from 0°C at a heating rate of 5°C / minute. Among the tan δ values ​​determined by temperature, the temperature that gave the highest tan δ was defined as the glass transition temperature and is shown in Table 1 below. The first bonding layer was formed from the same composition as the second bonding layer composition, and therefore, the first bonding layer also had the same glass transition temperature as shown in Table 1 below.

[0174] [Table 1]

[0175]

[0176] A: 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (CELLOXIDE 2021P, DAICEL CORPORATION)

[0177] B: Resorcinol diglycidyl ether (EX-201, NAGASE CHEMTEX)

[0178] C: Phenyl glycidyl ether (EX-141, Nagase Chemical Co., Ltd.)

[0179] D: 4-Hydroxybutyl acrylate (OSAKA ORGANIC)

[0180] E: Isodecyl acrylate (M-130, MIWON SPECIALTY CHEMICAL)

[0181] F: Phenol (EO) acrylate (M-140, Miwon Specialty Chemical Co., Ltd.)

[0182] G: Diphenyl-4-(phenylthio)phenylsulfonium hexafluorophosphate (CPI-100P, SAN-APRO)

[0183] H: 1-Hydroxycyclohexylphenyl ketone (IRGACURE 184, BASF)

[0184] I: 3-Glycidyloxypropyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd.)

[0185] The physical properties of the polarizers prepared in Examples and Comparative Examples were evaluated by the following methods, and the results are shown in Table 2.

[0186] (1) Peel strength: Each of the polarizers prepared in the examples and comparative examples was placed at 25°C for 2 minutes. Then, the polarizer was cut into a size of 25 mm × 150 mm (width × length) including a shading member (3 cm), and a double-sided adhesive film was attached to the lower surface of the second liquid crystal retardation film to fix the polarizer to a tensile tester (texture analyzer). By opening the shading member of the polarizer, the first liquid crystal retardation film of the polarizer was fixed to the fixture of the texture analyzer. Then, the polarizer was placed at 25°C for 72 hours. Thereafter, when the first liquid crystal retardation film and the second liquid crystal retardation film were peeled off at 25°C under the conditions of a peeling speed of 300 mm / min and a peeling angle of 90°, the peeling strength was measured and defined as the peeling strength:

[0187] A peel strength of less than 50 gf / 25 mm is rated x.

[0188] The peel strength of 50 gf / 25 mm or greater than 50 gf / 25 mm and less than 100 gf / 25 mm is rated as Δ.

[0189] A peel strength of 100 gf / 25 mm or greater was rated as o.

[0190] (2) Reliability (unit: %): Each of the polarizers prepared in Examples and Comparative Examples was cut into a sample having a size of 3 cm × 3 cm (length × width, MD of the polarizer × TD of the polarizer). The degree of polarization was measured with the second liquid crystal retardation film of the sample positioned facing the light-emitting surface of V-7100 (JASCO).

[0191] For the prepared sample, initial polarization (P1) was measured.

[0192] After the prepared samples were placed in a heated chamber (constant temperature of 85°C, high temperature) or a humid heated chamber (constant temperature of 60°C and constant humidity of 95%, high temperature / high humidity) for 500 hours, the polarization (P2, P3) was measured using the same method as above. The change in polarization was calculated using Equations 1 and 2.

[0193] (3) Flexibility: An 80-μm-thick polyethylene terephthalate (PET) film was attached to one surface of the polarizer via an acrylic adhesive, and an 80-μm-thick PET film was attached to the other surface thereof via an acrylic adhesive, and then the polarizer was cut into a size of 6 cm × 4 cm (length × width, length: MD of the polarizer, width: TD of the polarizer), thereby preparing a sample having a structure of PET film / polarizer / PET film.

[0194] According to IEC-62715, the sample is mounted on a flexibility tester so that the PET film closest to the polarizer can be placed on the inner side of the polarizer during the flexibility test. The sample is then repeatedly bent at 25°C under the conditions of a bend radius of 5 mm, a bending speed of 30 times / minute, and a bending angle of 180°. The flexibility is evaluated by counting the number of bends until the first crack or crease appears in the first liquid crystal retardation film and / or the second liquid crystal retardation film. Flexibility is evaluated according to the following criteria:

[0195] ○: Bending times is 100,000 times or more

[0196] Δ: Bending times is 50,000 times or more and less than 100,000 times

[0197] X: Bending times less than 50,000 times

[0198] (4) Curability:

[0199] In step (2), the laminate was left to stand for 24 hours after exposure, and then the joined portions were separated to evaluate curability.

[0200] ○: The liquid crystal retardation film is easily separated.

[0201] X: The bonding layer is not cured or sticks to your hands.

[0202] [Table 2]

[0203]

[0204]

[0205] As shown in Table 2, the polarizer for a light-emitting display according to the present invention exhibited good peel strength of the bonding layer with respect to the liquid crystal retardation film and exhibited good reliability and flexibility.

[0206] On the other hand, the polarizers of the comparative examples having the first bonding layer or the second bonding layer deviating from the present invention cannot achieve the object of the present invention.

[0207] It will be understood that although a few example embodiments have been described herein, various modifications, changes, alterations, and equivalent embodiments may be made by those skilled in the art without departing from the spirit and scope of the invention.

Claims

1. A polarizer for a light-emitting display, comprising: polarizer; as well as A first bonding layer, a first liquid crystal retardation film, a second bonding layer, and a second liquid crystal retardation film are sequentially stacked on the surface of the polarizer. The polarizers each have a polarization change ΔPE1 of 0.7% or less according to Equation 1 and a polarization change ΔPE2 of 0.7% or less according to Equation 2: [Equation 1] ΔPE1=|P1-P2|, wherein P1 indicates an initial polarization degree measured on a sample having a length of 3 cm and a width of 3 cm obtained by cutting the polarizer along the longitudinal direction (MD) of the polarizer and the transverse direction (TD) of the polarizer, and P2 indicates the degree of polarization measured on the sample after the sample was placed at a constant temperature of 85° C. for 500 hours; as well as [Equation 2] ΔPE2=|P1-P3|, wherein P1 indicates an initial polarization degree measured on a sample having a length of 3 cm and a width of 3 cm obtained by cutting the polarizer along the MD of the polarizer and the TD of the polarizer, and P3 indicates the degree of polarization measured on the sample having a length of 3 cm and a width of 3 cm after the sample is placed under constant temperature and humidity conditions of 60° C. and 95% for 500 hours, and The unit of polarization degree is %, wherein the second bonding layer is formed of a composition comprising an epoxy compound and a (meth)acrylate compound, wherein the (meth)acrylate compound comprises a hydrophobic (meth)acrylate compound, wherein the epoxy compound comprises an alicyclic epoxy compound, The amount of the alicyclic epoxy compound is 40 to 90 parts by weight relative to 100 parts by weight of the total of the epoxy compound and the (meth)acrylate compound. The amount of the (meth)acrylate compound is 25 to 65 parts by weight based on 100 parts by weight of the total of the epoxy compound and the (meth)acrylate compound. 2 . The polarizer for a light emitting display according to claim 1 , wherein the second bonding layer is directly formed on each of the first liquid crystal retardation film and the second liquid crystal retardation film.

3. The polarizer for a light-emitting display according to claim 1, wherein the hydrophobic (meth)acrylate compound comprises an unsubstituted linear or branched C6 to C 20 Alkyl (meth)acrylates and (meth)acrylates containing an unsubstituted aromatic group.

4. The polarizer for light-emitting display according to claim 3, wherein the polarizer contains unsubstituted linear or branched C6 to C 20 The (meth)acrylate of the alkyl group includes at least one of isodecyl (meth)acrylate and decyl (meth)acrylate. 5 . The polarizer for a light-emitting display according to claim 1 , wherein the epoxy compound further comprises a glycidyl ether containing an aromatic group. 6 . The polarizer for a light-emitting display according to claim 5 , wherein the glycidyl ether containing an aromatic group comprises at least one of phenyl glycidyl ether and resorcinol diglycidyl ether. 7 . The polarizer for a light-emitting display according to claim 1 , wherein the composition does not contain a (meth)acrylate compound containing a hydrophilic group. 8 . The polarizer for a light-emitting display according to claim 1 , wherein the composition further comprises a photocationic initiator and a photoradical initiator.

9. The polarizer for a light-emitting display according to claim 8, wherein the composition comprises: 35 to 90 parts by weight of the epoxy compound, 10 to 65 parts by weight of the (meth)acrylate compound, Based on 100 parts by weight of the epoxy compound and the (meth)acrylate compound in total, 1 part by weight to 10 parts by weight of the photocationic initiator, Based on 100 parts by weight of the total of the epoxy compound and the (meth)acrylate compound, 0.5 parts by weight to 10 parts by weight of the photo radical initiator. 10 . The polarizer for a light emitting display according to claim 1 , wherein the second bonding layer has a glass transition temperature of 70° C. to 110° C. 11 . The polarizer for a light-emitting display according to claim 1 , wherein the first bonding layer is formed of a composition comprising an epoxy compound and a (meth)acrylate compound, wherein the (meth)acrylate compound comprises a hydrophobic (meth)acrylate compound. 12 . The polarizer for a light-emitting display according to claim 11 , wherein the composition does not contain a (meth)acrylate compound containing a hydrophilic group. 13 . The polarizer for a light-emitting display according to claim 1 , wherein the first bonding layer has a glass transition temperature of 70° C. to 110° C.

14. The polarizer for a light-emitting display according to claim 1, wherein each of the first liquid crystal retardation film and the second liquid crystal retardation film is formed of a composition including at least one of an alicyclic group-containing (meth)acrylic liquid crystal compound and an aromatic group-containing (meth)acrylic liquid crystal compound. 15 . The polarizer for a light-emitting display according to claim 1 , further comprising a protective layer on the other surface of the polarizer. 16 . A light-emitting display comprising the polarizer for a light-emitting display according to claim 1 .

17. The light-emitting display of claim 16, wherein the light-emitting display comprises a foldable light-emitting display.

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