Adhesive film, optical member including the same, and optical display device including the same

Abstract

The present invention provides an adhesive film, an optical member including the same, and an optical display device including the same. The adhesive film is formed from a composition including a polymerization product of a monomer mixture containing an aromatic group-containing (meth)acrylic monomer and inorganic particles having a refractive index of about 1.5 or greater than 1.5, and the adhesive film has a refractive index of 1.55 or greater than 1.55 and a storage modulus of 0.3 MPa or less than 0.3 MPa at 25°C.

Description

[0001] Cross - reference to related applications

[0002] This application claims the benefit of Korean Patent Application No. 10 - 2021 - 0123757, filed on September 16, 2021, with the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference. Technical field

[0003] The present invention relates to an acrylic adhesive film, an optical member including the same, and an optical display device including the same. Background art

[0004] An organic light - emitting device has a thin - film laminated structure. In this structure, 80% or more of the light generated from the light - emitting layer is lost by being reflected or absorbed inside the organic light - emitting device or at its interface rather than being emitted through the front surface of the organic light - emitting device, resulting in deteriorated luminous efficacy. Due to the lower luminous efficacy, the organic light - emitting device needs to increase power consumption to achieve a target brightness and suffers from a reduced lifespan. To solve such problems, improving the luminous efficacy has become an important issue.

[0005] Regarding this, various studies have been conducted to improve the luminous efficacy by stacking patterned optical elements on the organic light - emitting device. For example, referring to Figure 2 , a structure in which an inorganic layer 200, a low - refractive - index organic layer 300, and a high - refractive - index organic layer 400 are sequentially stacked on the upper surface of the organic light - emitting device has been proposed. The inorganic layer 200 is formed of inorganic particles such as silicon nitride, silicon oxynitride, silicon dioxide, titanium oxide, aluminum oxide, etc., and has a high refractive index. Since the high - refractive - index organic layer 400 is adjacent to the inorganic layer 200, the high - refractive - index organic layer 400 needs to effectively adhere to the inorganic layer 200 and have a high refractive index such as 1.55 or more than 1.55 in order to improve visibility and luminous efficacy.

[0006] Generally, inorganic particles can be used to improve the refractive index. However, inorganic particles can make it difficult to control the compatibility with the organic (meth)acrylate adhesive in the adhesive film. In addition, when the adhesive film contains an excessive amount of inorganic particles to improve the refractive index, the adhesive film may suffer from an increase in storage modulus (G') and a decrease in peel strength. Summary of the invention

[0007] An object of the present invention is to provide an adhesive film having a high refractive index and a high adhesive strength.

[0008] Another object of the present invention is to provide an adhesive film having good step - embedding characteristics.

[0009] Still another object of the present invention is to provide an adhesive film having a low haze.

[0010] One aspect of the present invention relates to an adhesive film.

[0011] The adhesive film is formed from a composition comprising a polymerization product of a monomer mixture containing an aromatic group-containing (meth)acrylic monomer and inorganic particles having a refractive index of about 1.5 or greater than 1.5, and the adhesive film has a refractive index of 1.55 or greater than 1.55 and a storage modulus of 0.3 MPa or less than 0.3 MPa at 25°C.

[0012] Another aspect of the present invention relates to an optical member.

[0013] The optical member comprises the adhesive film according to the present invention.

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

[0015] The optical display device comprises the optical display device according to the present invention. Description of the Drawings

[0016] Figure 1 FIG. is a cross-sectional view of an optical display device according to an embodiment of the present invention.

[0017] Figure 2 FIG. is an exemplary cross-sectional view of a structure for improving the luminous efficacy of an organic light-emitting device.

[0018] Description of Reference Numerals

[0019] 100: Organic light-emitting device;

[0020] 200: Inorganic layer;

[0021] 300: Low refractive index organic layer;

[0022] 400, 500: High refractive index organic layers. Detailed Description of the Invention

[0023] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings so that those skilled in the art can easily practice the present invention. It should be understood that the present invention can be embodied in different ways and is not limited to the following embodiments.

[0024] In the drawings, parts not relevant to the description will be omitted for clarity. Throughout the specification, the same components will be denoted by the same reference numerals.

[0025] As used herein, spatially relative terms such as "upper" and "lower" are defined with reference to the accompanying drawings. Thus, it will be understood that "upper" and "lower" may be used interchangeably. It will be understood that when a layer is referred to as being "on" another layer, the layer may be formed directly on the other layer or an intervening layer may also be present. Thus, it will be understood that when a layer is referred to as being "directly on" another layer, no intervening layer is interposed therebetween.

[0026] As used herein, the term "(meth)acryloyl" means acryloyl and / or methacryloyl.

[0027] In the present text, the "refractive index" is a value measured in the visible spectrum, particularly at a wavelength of 633 nm.

[0028] In the present text, the "adhesion strength" is a value measured according to JIS 2107 with respect to a glass plate (alkali-free glass plate) as an adherend.

[0029] As used herein to represent a specific numerical range, the expression "X to Y" means "greater than or equal to X and less than or equal to Y" (X ≤ and ≤ Y).

[0030] The present invention relates to an adhesive film stacked on an upper surface of a patterned optical element. An inorganic layer is stacked on the upper surface of the optical element, and a pattern having a predetermined shape is formed on at least a part of the inorganic layer. The patterned optical element will be described in detail below.

[0031] The adhesive film according to the present invention improves the light extraction efficiency from the patterned optical element, thereby increasing the service life of the light-emitting device by achieving high brightness even at relatively low power consumption.

[0032] The adhesive film according to the present invention has good step-embedding characteristics with respect to the patterned optical element to ensure good lamination with respect to the patterned optical element. As used herein, "excellent lamination" means that the blank space between the patterned surface of the optical element and the adhesive film is minimized, and the patterned surface is completely embedded without generating bubbles, so that the adhesive film is in complete contact with the patterned surface. Thus, the adhesive film according to the present invention can improve the reliability of the display device by preventing detachment and / or separation between the patterned optical element and another optical element (e.g., a polarizing plate) stacked on the upper surface of the optical element. In addition, by minimizing the non-attached area between the patterned optical element and the adhesive film, the adhesive film according to the present invention does not suffer from deterioration of the luminous efficacy.

[0033] Despite the presence of inorganic particles for modifying the refractive index, the adhesive film according to the present invention has a low storage modulus to provide good step-embedding characteristics when stacked on the optical element, and has a low haze to be effectively used in an optical display device.

[0034] Hereinafter, an adhesive film according to an embodiment of the present invention will be described.

[0035] The adhesive film has a refractive index of 1.55 or greater than 1.55. In the case of this refractive index, when stacked on the light-emitting surface of the patterned optical element, the adhesive film can improve the light extraction efficiency of the light emitted from the light-emitting device. For example, the adhesive film may have a refractive index of 1.55 to 1.65, specifically 1.55, 1.56, 1.57, 1.58, 1.59, 1.60, 1.61, 1.62, 1.63, 1.64, or 1.65.

[0036] The adhesive film has a storage modulus of 0.3 MPa or less than 0.3 MPa at 25°C. In the case of this modulus, the adhesive film can exhibit good step-embedding characteristics. The adhesive film may have, for example, a storage modulus of 0.01 MPa to 0.3 MPa at 25°C, specifically 0.01 MPa, 0.02 MPa, 0.03 MPa, 0.04 MPa, 0.05 MPa, 0.06 MPa, 0.07 MPa, 0.08 MPa, 0.09 MPa, 0.1 MPa, 0.11 MPa, 0.12 MPa, 0.13 MPa, 0.14 MPa, 0.15 MPa, 0.16 MPa, 0.17 MPa, 0.18 MPa, 0.19 MPa, 0.2 MPa, 0.21 MPa, 0.22 MPa, 0.23 MPa, 0.24 MPa, 0.25 MPa, 0.26 MPa, 0.27 MPa, 0.28 MPa, 0.29 MPa, or 0.3 MPa.

[0037] The adhesive film may have an adhesive strength of about 800 g-force / inch or greater than 800 g-force / inch relative to a glass plate. In the case of this adhesive strength, the adhesive film can be reliably attached to the patterned optical element. The adhesive film may have, for example, an adhesive strength of about 800 g-force / inch to about 2,000 g-force / inch relative to a glass plate, specifically 800 g-force / inch, 850 g-force / inch, 900 g-force / inch, 950 g-force / inch, 1,000 g-force / inch, 1,050 g-force / inch, 1,100 g-force / inch, 1,150 g-force / inch, 1,200 g-force / inch, 1,250 g-force / inch, 1,300 g-force / inch, 1,350 g-force / inch, 1,400 g-force / inch, 1,450 g-force / inch, 1,500 g-force / inch, 1,550 g-force / inch, 1,600 g-force / inch, 1,650 g-force / inch, 1,700 g-force / inch, 1,750 g-force / inch, 1,800 g-force / inch, 1,850 g-force / inch, 1,900 g-force / inch, 1,950 g-force / inch, or 2,000 g-force / inch.

[0038] The adhesive film may have a haze of about 1% or less than 1%, for example, a haze of about 0.001% to about 0.5%, specifically 0.001%, 0.005%, 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45% or 0.5% of haze. Within this range, the adhesive film can be used in optical display devices.

[0039] The adhesive film is optically clear for use in optical display devices. In one embodiment, the adhesive film may have a light transmittance of about 90% or greater than 90%, for example, a light transmittance of about 90% to about 100%.

[0040] The adhesive film may have a thickness of about 50 microns or less than 50 microns, for example, a thickness of about 5 microns to about 30 microns. Within this range, the adhesive film can be applied to optical display devices.

[0041] The adhesive film can be formed by depositing the adhesive composition described below on one surface of a release film to a predetermined thickness, followed by heat curing (primary curing) using a thermal curing agent and UV curing (secondary curing) using a photoinitiator. The heat curing may include heat treating a coating formed by coating the adhesive composition on a release film, etc. at 100°C to 150°C for 3 minutes to 10 minutes. The UV curing may include irradiating with UV light of about 100 mW / cm² to about 1,000 mW / cm² and about 100 mJ / cm² to about 1,000 mJ / cm² using a lamp for UV radiation (e.g., a metal halide lamp).

[0042] Hereinafter, the adhesive composition will be described.

[0043] The adhesive composition may include a polymerization product of a monomer mixture containing at least one aromatic group-containing (meth)acrylic monomer, inorganic particles having a refractive index of about 1.5 or greater than 1.5, a curing agent, and a photoinitiator. Herein, "aromatic group" may mean a C 6 ~C 20 aryl group. The aryl group may include a monocyclic group, a polycyclic (fused) group, or a monocyclic-linked linking type (e.g., biphenyl) group. Here, "polymerization product" may include at least one of a copolymer, an oligomer, and a prepolymer.

[0044] To ensure a refractive index of 1.55 or greater than 1.55, the adhesive composition includes a polymerization product of a monomer mixture containing at least one aromatic group-containing (meth)acrylic monomer and inorganic particles having a refractive index of about 1.5 or greater than 1.5, and further includes a curing agent and a photoinitiator to prevent an excessive increase in the storage modulus of the adhesive film at 25°C, deterioration of the adhesive strength, and an increase in haze due to the presence of the inorganic particles.

[0045] The polymerization product of a monomer mixture containing at least one aromatic group-containing (meth)acrylic monomer can assist in achieving a refractive index of 1.55 or greater than 1.55 by increasing the refractive index of the adhesive film. The monomer mixture can contain at least one aromatic group-containing (meth)acrylic monomer and a hydroxy group-containing (meth)acrylic monomer.

[0046] The aromatic group-containing (meth)acrylic monomer can improve the refractive index of the adhesive film. In one embodiment, the aromatic group-containing (meth)acrylic monomer can have a refractive index of about 1.5 or greater than 1.5 in the homopolymer phase, such as about 1.55 to about 1.7, specifically 1.55, 1.56, 1.57, 1.58, 1.59, 1.6, 1.61, 1.62, 1.63, 1.64, 1.65, 1.66, 1.67, 1.68, 1.69, or 1.7. Within this range, the adhesive film can easily achieve a refractive index within the above range.

[0047] The aromatic group-containing (meth)acrylic monomer can have a glass transition temperature of about -30°C to about 40°C in the homopolymer phase. Within this range, severe hardening of the adhesive film can be prevented, and thus it can be more effectively attached to the patterned optical element. For example, the aromatic group-containing (meth)acrylic monomer can have a glass transition temperature of about -25°C to about 40°C, specifically about -30°C, -25°C, -20°C, -15°C, -10°C, -5°C, 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, or 40°C. Herein, the glass transition temperature in the homopolymer phase can be measured by typical methods known to those skilled in the art or by referring to the catalog of the corresponding product.

[0048] The aromatic group-containing (meth)acrylic monomer can contain one aromatic group, preferably at least two aromatic groups. When used in the same amount, compared with the monomer containing one aromatic group, the monomer containing at least two aromatic groups can more effectively help increase the refractive index of the adhesive film. In one embodiment, the aromatic group-containing (meth)acrylic monomer can contain two to five aromatic groups.

[0049] In one embodiment, the aromatic group-containing (meth)acrylic monomer can have a structure represented by Formula 1:

[0050] [Formula 1]

[0051]

[0052] where * is the connection site of the element; and

[0053] X is a single bond, C 1 ~C 5 alkylene or oxygen (O).

[0054] The aromatic group-containing (meth)acrylic monomer may be a monomer containing one (meth)acrylate group, i.e., a monofunctional (meth)acrylate. Therefore, it is possible to prevent the adhesive film from becoming too hard due to excessive polymerization of the monomer during the preparation of the polymerization product, thereby minimizing the failure of adhesion to the patterned optical element.

[0055] In one embodiment, the aromatic group-containing (meth)acrylic monomer may have a structure represented by Formula 2:

[0056] [Formula 2]

[0057]

[0058] wherein X is a single bond, C 1 ~C 5 alkylene or oxygen (O);

[0059] Y is hydrogen or methyl;

[0060] R 1 is C 1 ~C 10 alkyl, halogen or C 6 ~C 20 aryl;

[0061] n is an integer from 0 to 5; and

[0062] R 2 is a single bond, C 1 ~C 10 alkylene or C 1 ~C 30 monoalkyleneoxy or polyalkyleneoxy.

[0063] In one embodiment, in Formula 2, the C 1 ~C 30 monoalkyleneoxy or polyalkyleneoxy may be -*( -O-R 3 -)n-* (* is the bonding site of the element, and R 3 is C 1 ~C 3 alkylene, and n is an integer from 1 to 10).

[0064] For example, the aromatic group-containing (meth)acrylic monomer may include at least one selected from the following: phenylbenzyl (meth)acrylate, including o-phenylbenzyl acrylate, m-phenylbenzyl acrylate, p-phenylbenzyl acrylate, etc.; phenoxybenzyl (meth)acrylate; biphenyl (meth)acrylate, including 4-biphenyl (meth)acrylate, etc.; monoethoxylated phenylphenoxy (meth)acrylate; poly(ethoxylated) phenylphenoxy (meth)acrylate, including ethoxylated (2) phenylphenoxy (meth)acrylate, etc.

[0065] In one embodiment, the monomer mixture may include at least one type of aromatic group-containing (meth)acrylic monomer.

[0066] In another embodiment, since the aromatic group-containing (meth)acrylic monomers have different properties in terms of refractive index, glass transition temperature, etc. in the homopolymer phase, a mixture of at least two types of aromatic group-containing (meth)acrylic monomers allows the effects of the present invention to be more easily implemented.

[0067] In one example, the aromatic group-containing (meth)acrylic monomer may be a mixture of a first aromatic group-containing (meth)acrylic monomer in which X is oxygen (O) in Formula 2 and a second aromatic group-containing (meth)acrylic monomer in which X is a single bond or C 1 ~C 5 ~C alkylene. Using this mixture, the adhesive composition can improve the adhesion strength and flexibility of the adhesive film.

[0068] The first aromatic group-containing (meth)acrylic monomer may include, but is not limited to, phenoxybenzyl (meth)acrylate. The second aromatic group-containing (meth)acrylic monomer may include, but is not limited to, biphenyl (meth)acrylate, phenylbenzyl acrylate, etc.

[0069] In the monomer mixture, the first aromatic group-containing (meth)acrylic monomer may be present in an amount of about 70% to about 90% by weight, specifically in an amount of 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89% or 90% by weight, for example, in an amount of about 70% to about 85% by weight. In the monomer mixture, the second aromatic group-containing (meth)acrylic monomer may be present in an amount of about 1% to about 15% by weight, specifically in an amount of 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15% by weight, for example, in an amount of about 5% to about 15% by weight.

[0070] In another example, the aromatic group-containing (meth)acrylic monomer may be a first aromatic group-containing (meth)acrylic monomer in which R 2 is C 1 ~C 10 ~C alkylene and a second aromatic group-containing (meth)acrylic monomer in which R 2 is C 1 ~C 30Mixture of second aromatic group-containing (meth)acrylic monomers of (poly)alkylene oxides. In this mixture, the second aromatic group-containing (meth)acrylic monomers impart flexibility to improve the lamination of the adhesive film to the patterned optical element.

[0071] The first aromatic group-containing (meth)acrylic monomer may include, but is not limited to, phenylbenzyl acrylate and / or phenoxybenzyl (meth)acrylate. The second aromatic group-containing (meth)acrylic monomer may include, but is not limited to, monoethoxylated phenylphenoxy (meth)acrylate and / or poly(ethoxylated) phenylphenoxy (meth)acrylate. In the monomer mixture, the first aromatic group-containing (meth)acrylic monomer may be present in an amount of about 70 wt% to about 90 wt%, specifically in an amount of 70 wt%, 71 wt%, 72 wt%, 73 wt%, 74 wt%, 75 wt%, 76 wt%, 77 wt%, 78 wt%, 79 wt%, 80 wt%, 81 wt%, 82 wt%, 83 wt%, 84 wt%, 85 wt%, 86 wt%, 87 wt%, 88 wt%, 89 wt% or 90 wt%, for example, in an amount of about 70 wt% to about 80 wt%. In the monomer mixture, the second aromatic group-containing (meth)acrylic monomer may be present in an amount of about 1 wt% to about 15 wt%, specifically in an amount of 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt% or 15 wt%, for example, in an amount of about 5 wt% to about 15 wt%.

[0072] In the monomer mixture, at least one aromatic group-containing (meth)acrylic monomer may be present in an amount of about 75 wt% to about 95 wt%, specifically in an amount of 75 wt%, 76 wt%, 77 wt%, 78 wt%, 79 wt%, 80 wt%, 81 wt%, 82 wt%, 83 wt%, 84 wt%, 85 wt%, 86 wt%, 87 wt%, 88 wt%, 89 wt%, 90 wt%, 91 wt%, 92 wt%, 93 wt%, 94 wt% or 95 wt%, for example, in an amount of about 75 wt% to about 90 wt% or about 75 wt% to about 85 wt%. Within this range, the adhesive composition can ensure the refractive index of the adhesive film without deteriorating the adhesive strength of the adhesive film.

[0073] The hydroxy group-containing (meth)acrylic monomer may include a (meth)acrylic monomer containing a C 1 to C 20 alkyl group having at least one hydroxy group at the ester site and / or a C 3 to C 20Naphthenic (meth)acrylic monomers.

[0074] Hydroxy-containing (meth)acrylic monomers may have a lower glass transition temperature in the homopolymer phase than aromatic group-containing (meth)acrylic monomers. Thus, hydroxy-containing (meth)acrylic monomers can improve the adhesion strength of the adhesive film such that the adhesive film effectively adheres to the patterned optical element. For example, hydroxy-containing (meth)acrylic monomers may have a glass transition temperature of about -10 °C or less than -10 °C in the homopolymer phase, specifically a glass transition temperature of -50 °C, -45 °C, -40 °C, -35 °C, -30 °C, -25 °C, -20 °C, -15 °C or -10 °C, such as a glass transition temperature of about -50 °C to about -10 °C.

[0075] In one embodiment, the hydroxy-containing (meth)acrylic monomer may be a (meth)acrylic monomer containing a C 1 to C 20 alkyl group having at least one hydroxyl group at the ester site. Specifically, the hydroxy-containing (meth)acrylic monomer may include at least one selected from the following: 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 1-chloro-2-hydroxypropyl (meth)acrylate. These monomers may be used alone or as a mixture thereof.

[0076] In the monomer mixture, the hydroxy-containing (meth)acrylic monomer may be present in an amount of about 5 wt% to about 25 wt%, specifically in an amount of 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt% or 25 wt%, such as in an amount of about 10 wt% to about 25 wt% or about 15 wt% to about 25 wt%. Within this range, the adhesive composition can easily achieve the effects of the present invention. In the present invention, the hydroxy-containing (meth)acrylic monomer is used in a relatively high content to provide an adhesive film that can effectively adhere to the patterned optical element.

[0077] In the monomer mixture, the total amount of the aromatic group-containing (meth)acrylic monomer and the hydroxy-containing (meth)acrylic monomer may be present in an amount of 95 wt% or more than 95 wt%, such as in an amount of 98 wt% to 100 wt%, preferably in an amount of 100 wt%.

[0078] The monomer mixture may not contain a C 1 to C 10Linear or branched alkyl (meth)acrylates. Containing C 1 ~C 10 The linear or branched alkyl (meth)acrylates may include at least one selected from the following: methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, and dodecyl (meth)acrylate.

[0079] The polymerization product may have a weight-average molecular weight of about 100,000 g / mol to about 5,000,000 g / mol, such as a weight-average molecular weight of about 100,000 g / mol to about 3,000,000 g / mol or about 100,000 g / mol to about 2,000,000 g / mol. Within this range, the adhesive composition can ensure the adhesion strength and durability reliability of the adhesive film.

[0080] The polymerization product can be prepared by adding an initiator to a monomer mixture and then polymerizing. The initiator may include a thermal initiator. The thermal initiator can be a typical thermal initiator well-known to those skilled in the art. For example, the initiator can be a typical thermal initiator containing an azo-based polymerization initiator and / or a peroxide (such as benzoyl peroxide and acetyl peroxide).

[0081] The initiator may be present in an amount of about 0.01 parts by weight to about 0.5 parts by weight, preferably in an amount of about 0.01 parts by weight to about 0.1 parts by weight, more preferably in an amount of about 0.03 parts by weight to about 0.08 parts by weight, based on 100 parts by weight of the monomer mixture. Within this range, the initiator can easily form a polymerization product.

[0082] The polymerization can be carried out by typical polymerization methods well-known to those skilled in the art, such as suspension polymerization, emulsion polymerization, solution polymerization, etc. The polymerization can be carried out at about 60°C to about 80°C for about 4 hours to about 8 hours. The polymerization product can be easily obtained.

[0083] In the composition, based on the solid content, the polymeric product may be present in an amount of about 40 wt% to about 90 wt%, specifically in an amount of 40 wt%, 41 wt%, 42 wt%, 43 wt%, 44 wt%, 45 wt%, 46 wt%, 47 wt%, 48 wt%, 49 wt%, 50 wt%, 51 wt%, 52 wt%, 53 wt%, 54 wt%, 55 wt%, 56 wt%, 57 wt%, 58 wt%, 59 wt%, 60 wt%, 61 wt%, 62 wt%, 63 wt%, 64 wt%, 65 wt%, 66 wt%, 67 wt%, 68 wt%, 69 wt%, 70 wt%, 71 wt%, 72 wt%, 73 wt%, 74 wt%, 75 wt%, 76 wt%, 77 wt%, 78 wt%, 79 wt%, 80 wt%, 81 wt%, 82 wt%, 83 wt%, 84 wt%, 85 wt%, 86 wt%, 87 wt%, 88 wt%, 89 wt% or 90 wt%, for example in an amount of about 50 wt% to about 90 wt%. Within this range, the adhesive composition can easily achieve the effects of the present invention.

[0084] Inorganic particles having a refractive index of about 1.5 or greater than 1.5 improve the refractive index of the adhesive film, so that the adhesive film can easily achieve the refractive index according to the present invention.

[0085] Inorganic particles having a refractive index of about 1.5 or greater than 1.5 more preferably have a refractive index of about 1.5 to about 2.8, specifically a refractive index of 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7 or 2.8, and more preferably a refractive index of about 1.5 to about 2.0. Within this range, the adhesive film can easily achieve the refractive index according to the present invention.

[0086] The inorganic particles having a refractive index of about 1.5 or greater than 1.5 can be selected from typical inorganic particles well-known to those skilled in the art. For example, the inorganic particles having a refractive index of about 1.5 or greater than 1.5 may include zirconia (ZrO 2 ) and / or titanium dioxide (TiO 2 ). Preferably, the inorganic particles having a refractive index of about 1.5 or greater than 1.5 include zirconia.

[0087] Inorganic particles having a refractive index of about 1.5 or greater than 1.5 may have an average particle size (D50) of about 5 nanometers to about 50 nanometers, specifically 5 nanometers, 6 nanometers, 7 nanometers, 8 nanometers, 9 nanometers, 10 nanometers, 11 nanometers, 12 nanometers, 13 nanometers, 14 nanometers, 15 nanometers, 16 nanometers, 17 nanometers, 18 nanometers, 19 nanometers, 20 nanometers, 21 nanometers, 22 nanometers, 23 nanometers, 24 nanometers, 25 nanometers, 26 nanometers, 27 nanometers, 28 nanometers, 29 nanometers, 30 nanometers, 31 nanometers, 32 nanometers, 33 nanometers, 34 nanometers, 35 nanometers, 36 nanometers, 37 nanometers, 38 nanometers, 39 nanometers, 40 nanometers, 41 nanometers, 42 nanometers, 43 nanometers, 44 nanometers, 45 nanometers, 46 nanometers, 47 nanometers, 48 nanometers, 49 nanometers or 50 nanometers, for example an average particle size (D50) of about 10 nanometers to about 40 nanometers, for example an average particle size (D50) of about 15 nanometers to about 30 nanometers. Within this range, the inorganic particles can be included in the adhesive film without affecting the peel strength and haze of the adhesive film. Here, the "average particle size (D50)" can be measured by typical methods well known to those skilled in the art. For example, the average particle size (D50) means the particle size corresponding to 50 wt% in the weight cumulative distribution of the inorganic particles as measured using a particle size analyzer.

[0088] Inorganic particles having a refractive index of about 1.5 or greater than 1.5 may be surface-treated to reduce the haze of the adhesive film by improving dispersion when mixed with the polymerization product. The surface treatment can be carried out by typical methods known to those skilled in the art. For example, inorganic particles having a refractive index of about 1.5 or greater than 1.5 can be surface-treated with a (meth)acrylic acid compound.

[0089] Inorganic particles having a refractive index of about 1.5 or greater than 1.5 can be present in the adhesive composition in an amount of about 5 wt% to about 60 wt% (based on the solid content). Specifically, inorganic particles having a refractive index of about 1.5 or greater than 1.5 can be present in an amount of 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, 40 wt%, 41 wt%, 42 wt%, 43 wt%, 44 wt%, 45 wt%, 46 wt%, 47 wt%, 48 wt%, 49 wt%, 50 wt%, 51 wt%, 52 wt%, 53 wt%, 54 wt%, 55 wt%, 56 wt%, 57 wt%, 58 wt%, 59 wt% or 60 wt%, for example, in an amount of about 5 wt% to about 55 wt% or about 10 wt% to about 50 wt%. Within this range, the adhesive film can easily achieve a refractive index of about 1.5 or greater than 1.5 and good peel strength, while meeting the modulus condition to provide good step-embedding characteristics.

[0090] Inorganic particles having a refractive index of about 1.5 or greater than 1.5 can be present in an amount of about 1 part by weight to about 150 parts by weight relative to 100 parts by weight of the (meth)acrylic acid polymer product having an aromatic group and a hydroxyl group. For example, the inorganic particles can be present in an amount of about 1 part by weight, 5 parts by weight, 10 parts by weight, 15 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight, 45 parts by weight, 50 parts by weight, 55 parts by weight, 60 parts by weight, 65 parts by weight, 70 parts by weight, 75 parts by weight, 80 parts by weight, 85 parts by weight, 90 parts by weight, 95 parts by weight, 100 parts by weight, 105 parts by weight, 110 parts by weight, 115 parts by weight, 120 parts by weight, 125 parts by weight, 130 parts by weight, 135 parts by weight, 140 parts by weight, 145 parts by weight or 150 parts by weight relative to 100 parts by weight of the polymer product, for example, in an amount of about 5 parts by weight to about 120 parts by weight or about 10 parts by weight to about 80 parts by weight. Within this range, the adhesive film can ensure a refractive index of 1.5 or greater than 1.5 and can easily achieve high peel strength and good modulus.

[0091] The curing agent can improve the adhesion strength of the adhesive film through thermal curing of the polymerization product, while enabling the adhesive film to have a modulus of 0.3 MPa or less than 0.3 MPa at 25°C. The curing agent can include at least one selected from the following: isocyanate curing agent, epoxy curing agent, metal chelate curing agent, and aziridine curing agent. Preferably, the curing agent is an isocyanate curing agent.

[0092] The isocyanate curing agent can include: hexamethylene diisocyanate (HDI); toluene diisocyanate (TDI), including 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, etc.; 4,4'-methylene diphenyl diisocyanate (MDI); xylylene diisocyanate (XDI), including 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, etc.; hydrogenated toluene diisocyanate; isophorone diisocyanate; 1,3-bis(isocyanatomethyl)cyclohexane; tetramethyl xylylene diisocyanate; 1,5-naphthalene diisocyanate; 2,2,4-trimethylhexamethylene diisocyanate; 2,4,4-trimethylhexamethylene diisocyanate; toluene diisocyanate adduct of trimethylolpropane, including trimer adduct of trimethylolpropane / toluene diisocyanate; xylylene diisocyanate adduct of trimethylolpropane; and adducts of isocyanate curing agents, such as triphenylmethane triisocyanate, methylene bis(triisocyanate), etc.

[0093] The curing agent (e.g., isocyanate curing agent) can be present in an amount of about 0.01 parts by weight to about 5 parts by weight, specifically 0.01 parts by weight, 0.05 parts by weight, 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1 part by weight, 1.1 parts by weight, 1.2 parts by weight, 1.3 parts by weight, 1.4 parts by weight, 1.5 parts by weight, 1.6 parts by weight, 1.7 parts by weight, 1.8 parts by weight, 1.9 parts by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, or 5 parts by weight, for example, in an amount of about 0.1 parts by weight to about 3 parts by weight, relative to 100 parts by weight of the polymerization product. Within this range, the adhesive composition can easily achieve the adhesion strength and storage modulus of the adhesive film according to the present invention.

[0094] In the adhesive composition, based on the solid content, the curing agent may be present in an amount of about 0.01 wt% to about 3 wt%, specifically in an amount of 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.35 wt%, 0.4 wt%, 0.45 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, 2 wt%, 2.1 wt%, 2.2 wt%, 2.3 wt%, 2.4 wt%, 2.5 wt%, 2.6 wt%, 2.7 wt%, 2.8 wt%, 2.9 wt% or 3 wt%, for example in an amount of about 0.01 wt% to about 1 wt%. Within this range, the adhesive composition can easily achieve the effects of the present invention.

[0095] The product produced by thermal curing is cured by a photoinitiator to improve the adhesion strength of the adhesive film, while enabling the adhesive film to easily achieve a storage modulus and refractive index of 0.3 MPa or less at 25°C.

[0096] The photoinitiator may include any typical photoinitiator capable of undergoing a photocuring reaction as a free radical photoinitiator, without limitation. For example, the photoinitiator may include a triazine initiator, an acetophenone initiator, a benzophenone initiator, a thioxanthone initiator, a benzoin initiator, a phosphorus initiator, a ketone initiator, an oxime initiator, or a mixture thereof.

[0097] The photoinitiator may be present in an amount of about 0.01 parts by weight to about 5 parts by weight relative to 100 parts by weight of the polymerization product, specifically in an amount of 0.01 parts by weight, 0.05 parts by weight, 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1 part by weight, 1.1 parts by weight, 1.2 parts by weight, 1.3 parts by weight, 1.4 parts by weight, 1.5 parts by weight, 1.6 parts by weight, 1.7 parts by weight, 1.8 parts by weight, 1.9 parts by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight or 5 parts by weight, for example in an amount of about 0.1 parts by weight to about 3 parts by weight. Within this range, the adhesive composition can satisfy both the durability and adhesion strength of the adhesive film.

[0098] In the composition, based on the solid content, the photoinitiator may be present in an amount of about 0.01% to about 3% by weight, specifically in an amount of 0.01% by weight, 0.05% by weight, 0.1% by weight, 0.2% by weight, 0.3% by weight, 0.4% by weight, 0.5% by weight, 0.6% by weight, 0.7% by weight, 0.8% by weight, 0.9% by weight, 1% by weight, 1.1% by weight, 1.2% by weight, 1.3% by weight, 1.4% by weight, 1.5% by weight, 1.6% by weight, 1.7% by weight, 1.8% by weight, 1.9% by weight, 2% by weight or 3% by weight, for example in an amount of about 0.01% to about 1.5% by weight. Within this range, the adhesive composition can easily achieve the effects of the present invention.

[0099] The adhesive composition may further comprise a silane coupling agent.

[0100] The silane coupling agent can improve the adhesion strength and reliability of the adhesive film.

[0101] The silane coupling agent may comprise at least one selected from the following: an acetylacetone silane coupling agent having an acetylacetonyl group, an acetoacetic acid silane coupling agent having an acetoacetyl group, and an epoxy silane coupling agent having an epoxy group. For example, the epoxy silane coupling agent may comprise 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, but is not limited thereto. The acetylacetone silane coupling agent or the acetoacetic acid silane coupling agent may comprise 3-(trimethoxysilyl)propyl acetoacetate, acetylacetone trimethoxysilane, and acetylacetone triethoxysilane, but is not limited thereto.

[0102] The silane coupling agent may be present in an amount of about 0.1 part to about 1 part by weight relative to 100 parts by weight of the polymerization product, specifically in an amount of about 0.1 part to about 0.5 part by weight. Within this range, the adhesive composition can further improve the adhesion strength of the adhesive film.

[0103] The adhesive composition may further comprise a curing catalyst, additives, etc.

[0104] The curing catalyst may comprise, for example, tin-based catalysts (such as dibutyltin dilaurate, dioctyltin dilaurate, etc.) and iron-based catalysts (such as iron(III) acetylacetonate, iron(III) tris(hexane-2,4-dionate), iron(III) tris(heptane-2,4-dionate), etc.) as metal catalysts. The curing catalyst may be present in an amount of about 0.001 part to about 0.01 part by weight relative to 100 parts by weight of the polymerization product, specifically in an amount of about 0.005 part to about 0.01 part by weight. Within this range, the adhesive composition can more easily achieve the effects of the present invention.

[0105] The additive may be a typical additive well-known to those skilled in the art and may include, for example, a leveling agent, an antistatic agent, particles, a filler, an antioxidant, a heat stabilizer, a UV absorber, a surfactant, etc. The additive may be present in an amount of about 0.001 parts by weight to about 5 parts by weight, specifically 0.001 parts by weight, 0.005 parts by weight, 0.01 parts by weight, 0.05 parts by weight, 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1 part by weight, 1.1 parts by weight, 1.2 parts by weight, 1.3 parts by weight, 1.4 parts by weight, 1.5 parts by weight, 1.6 parts by weight, 1.7 parts by weight, 1.8 parts by weight, 1.9 parts by weight, 2 parts by weight, 2.1 parts by weight, 2.2 parts by weight, 2.3 parts by weight, 2.4 parts by weight, 2.5 parts by weight, 2.6 parts by weight, 2.7 parts by weight, 2.8 parts by weight, 2.9 parts by weight, 3 parts by weight, 4 parts by weight or 5 parts by weight, for example, in an amount of about 0.01 parts by weight to about 1 part by weight. Within this range, the additive can ensure its inherent effect without affecting the properties of the adhesive layer.

[0106] In the composition, in terms of the solid content, the additive may be present in an amount of about 0.001 wt% to about 3 wt%. Within this range, the additive can ensure its inherent effect without affecting the properties of the adhesive layer.

[0107] The adhesive composition may be a solvent-free composition. Alternatively, the adhesive composition may further contain a solvent. The adhesive composition containing a solvent can produce a thin adhesive film while ensuring good coatability. The solvent may be a typical solvent well-known to those skilled in the art. For example, the solvent may include at least one selected from methyl ethyl ketone, ethyl acetate, and toluene.

[0108] The optical member according to the present invention includes the adhesive film according to the present invention.

[0109] Next, an optical member according to an embodiment will be described.

[0110] The optical member includes a first adhesive film and a polarizing plate stacked on the upper surface of the first adhesive film, wherein the first adhesive film may include the adhesive film according to the present invention.

[0111] The polarizing plate may include a polarizer and a protective layer or a protective film stacked on at least one surface of the polarizer. The polarizer, the protective layer, and the protective film may be selected from typical types known to those skilled in the art.

[0112] The optical member may further include a second adhesive film located between the first adhesive film and the polarizing plate. The second adhesive film has a lower refractive index than the first adhesive film. The second adhesive film can improve the reliability of the optical member by improving the adhesion of the first adhesive film to the polarizing plate.

[0113] The optical display device includes the adhesive film or the optical member according to the present invention. The optical display device may include a light-emitting device display device, and the light-emitting device display device includes an organic light-emitting device, an inorganic light-emitting device, an organic-inorganic light-emitting device, etc.

[0114] Next, reference will be made to Figure 1 describe an optical display device according to an embodiment of the present invention.

[0115] Reference Figure 1 , the optical display device may include an organic light-emitting device 100 and a patterned optical element and a high-refractive-index organic layer 500 stacked on the upper surface of the organic light-emitting device 100, wherein the patterned optical element includes an inorganic layer 200 and a low-refractive-index organic layer 300 sequentially stacked on the organic light-emitting device 100, and the high-refractive-index organic layer 500 includes the adhesive film according to the present invention. The low-refractive-index organic layer 300 is disposed on the inorganic layer 200 and may be formed into a raised pattern having a predetermined cross-sectional shape. The patterned optical element can ensure process stability. As Figure 2 shown, the low-refractive-index organic layer 300 may have a patterned surface including a plurality of patterned elements having a predetermined cross-section and spaced apart from each other by a distance of 10 μm to 1,000 μm and having a pattern height, i.e., a step height, of 1 μm to 100 μm. The low-refractive-index organic layer 300 may be formed of an acrylic material, but is not limited thereto.

[0116] Next, the present invention will be described in more detail with reference to examples. However, it should be understood that these examples are provided for illustration only and should not be construed as limiting the present invention in any way.

[0117] Preparation Example 1: Preparation of (meth)acrylic polymerization product

[0118] 50 parts by weight of ethyl acetate was placed in a 1 L reactor equipped with a cooling device to facilitate temperature adjustment under a nitrogen atmosphere. 100 parts by weight of a monomer mixture was added to the reactor, and the 100 parts by weight of the monomer mixture contained 85 parts by weight of phenoxy benzyl acrylate (PoBA) and 15 parts by weight of 4-hydroxybutyl acrylate (4-HBA, glass transition temperature in the homopolymer phase: -40 °C). A mixture of ethyl acetate and methyl ethyl ketone was further added to the reactor. To remove oxygen from the monomer mixture by replacing it with nitrogen, nitrogen was added to the reactor for 1 hour, and then the internal temperature of the reactor was maintained at 70 °C. After uniformly stirring the monomer mixture, 0.05 parts by weight of azobisisobutyronitrile (AIBN) was added as a thermal initiator to the mixture initiator, and then polymerization was carried out for 4 hours to prepare a solution containing a (meth)acrylic acid polymerization product. Next, ethyl acetate was added to the solution to prepare a (meth)acrylic acid polymerization product solution having a solid content of 35% by weight.

[0119] Preparation Example 2 to Preparation Example 4: Preparation of (meth)acrylic acid polymerization product

[0120] Except that the content of each monomer and the polymerization time were changed as listed in Table 1 (unit: parts by weight), a (meth)acrylic acid polymerization product solution was prepared in the same manner as in Preparation Example 1. In Table 1 below, "-" means that the corresponding component is absent.

[0121] Table 1

[0122]

[0123] * In Table 1,

[0124] PoBA: Phenoxy benzyl acrylate,

[0125] 4-HBA: 4-Hydroxybutyl acrylate,

[0126] BPMA: Biphenyl methacrylate,

[0127] n-BA: n-Butyl acrylate,

[0128] MA: Methyl acrylate,

[0129] AA: Acrylic acid, and

[0130] HEMA: 2-Hydroxyethyl methacrylate.

[0131] Details of the components used in the examples and comparative examples are as follows.

[0132] (1) Zirconia particle dispersion liquid

[0133] A: ZP-158 (Nippon Shokubai Co., Ltd., average particle size (D50): 20 nm, refractive index: 1.75)

[0134] B: ZP-159 (Nippon Shokubai Co., Ltd., average particle size (D50): 20 nm, refractive index: 1.7)

[0135] (2) Curing agent

[0136] A: Xylylene diisocyanate curing agent (TD-75, Soken)

[0137] B: Hexamethylene diisocyanate curing agent (CK-164, NCI)

[0138] (3) Photoinitiator

[0139] A: Omnirad 127 (iGM Co., Ltd.)

[0140] B: Omnirad 651 (iGM Co., Ltd.)

[0141] (4) Additive

[0142] Leveling agent: BYK-3700 (hydroxyl-containing organosilicon modifier, BYK)

[0143] Example 1

[0144] In terms of the solid content, 10 parts by weight of toluene was added to the mixture of the (meth)acrylic acid polymerization product, zirconia particle dispersion liquid, curing agent, photoinitiator, and additive prepared in Preparation Example 1, and then the mixture was stirred for 30 minutes to prepare an adhesive composition. Table 2 shows the content (unit: parts by weight) of each of the (meth)acrylic acid polymerization product, zirconia, curing agent, photoinitiator, and additive of Preparation Example 1 in the adhesive composition.

[0145] Deposit the prepared adhesive composition on the first release film to a predetermined thickness (peeling strength of the following adhesive film relative to the first release film: 12 g force / inch, PET film, RPK501, Toray) and dry it at 120 °C for 4 minutes, and then initially cure it using a curing agent to form a 20-μm-thick coating. Stack the second release film (peeling strength of the adhesive film relative to the second release film: 3 g force / inch, PET film, RPK201, Toray) on the coating and subject it to secondary curing using a photoinitiator by UV radiation under the conditions of 400 mW / cm² and 200 mJ / cm² using a metal halide lamp that blocks oxygen, thereby preparing an adhesive sheet in which the first release film, the adhesive film (thickness: 20 μm), and the second release film are stacked in sequence.

[0146] Examples 2 to 6

[0147] Except that the type of each component of the adhesive composition and / or its content in terms of solid content are changed as shown in Table 2, prepare adhesive sheets each containing a first release film, an adhesive film (thickness: 20 μm), and a second release film stacked in sequence in the same manner as in Example 1.

[0148] Comparative Examples 1 to 5

[0149] Except that the type of each component of the adhesive composition and / or its content in terms of solid content are listed and changed as shown in Table 2, prepare adhesive sheets each containing a first release film, an adhesive film (thickness: 20 μm), and a second release film stacked in sequence in the same manner as in Example 1.

[0150] Evaluate the adhesive sheets of the examples and comparative examples in Table 2 and the results are shown in Table 3.

[0151] (1) Storage modulus (unit: MPa): Measure the modulus on the adhesive film obtained by removing the first release film and the second release film from each of the adhesive sheets. Use an ARES rheometer (MCR-501, Anton Parr) as a dynamic viscoelastic instrument to evaluate the modulus under temperature scanning conditions. Stack multiple adhesive films prepared in each of the examples and comparative examples to form a 600-μm-thick laminate. Punch the laminate with an 8-mm diameter punching machine to prepare a sample. Apply a normal force of 1.0 N to the sample using an 8-mm fixture, measure the modulus at 25 °C, and simultaneously increase the temperature from -30 °C to 100 °C at a rate of 10 °C / min under the conditions of a frequency of 1 Hz and a strain of 1%.

[0152] (2) Step embedding property: An adhesive film is obtained by removing two release films from each of the adhesive sheets of the first release film / adhesive film / second release film prepared from the examples and comparative examples, and cut into a size of 2.5 cm × 10 cm (width × length). The adhesive film is subjected to high-pressure treatment at 3.5 bar and 55 °C for 1,000 seconds, and attached to the upper surface of a glass plate having a 2-μm-thick pattern thereon. Bubbles are observed at the interface between the adhesive film and the glass plate through a microscope. No bubble generation is rated as OK and any bubble generation is rated as NG.

[0153] (3) Refractive index: An adhesive film is obtained by removing two release films from each of the adhesive sheets. The refractive index of the adhesive film is measured at a wavelength of 633 nm using a prism coupler (Metricon, Model 2010 / M), where the adhesive film is brought into contact with the rutile prism base of the prism coupler with an air gap of 0.1 μm therebetween.

[0154] (4) Haze (unit: %): An adhesive film is obtained by removing two release films from each of the adhesive sheets of the first release film / adhesive film / second release film prepared from the examples and comparative examples, and attached to a non-alkali glass plate. Subsequently, the haze of the adhesive film is measured using a haze meter NDH-9000.

[0155] (5) Adhesive strength (unit: g-force / inch): The adhesive strength is the 180° adhesive strength between the adhesive film and the glass plate (non-alkali glass plate), and is measured according to JIS 2107. The adhesive sheet is cut into a size of 25 mm × 100 mm (width × length). Next, with the second release film removed from the adhesive sheet, the adhesive film is attached to the glass plate [35 mm × 110 mm (width × length)] and the first release film is removed from the adhesive film. In a 30-kgf dynamometer, the glass plate and the adhesive film are respectively coupled to the upper and lower jigs of a texture analyzer, and the load (adhesive strength) is measured when separating the adhesive film from the glass plate under the conditions of a stretching rate of 300 mm / min, a stretching angle of 180°, and a stretching temperature of 25 °C.

[0156] Table 2

[0157]

[0158] E: Example, CE: Comparative example, PE: Preparation example

[0159] As shown in Table 2, the adhesive film according to the present invention has a high refractive index, high adhesive strength, good step-embedding characteristics, and low haze. Although not shown in Table 2, the adhesive film according to the present invention has a refractive index of 1.55 or greater than 1.55, and improves the extraction efficiency of light emitted from a patterned optical element, thereby achieving high brightness even at relatively low power consumption to ensure a long service life of the light-emitting device. Therefore, the present invention provides an adhesive film having a high refractive index, high adhesive strength, good step-embedding characteristics, and low haze.

[0160] In contrast, the adhesive film of the comparative example fails to meet the features of the present invention.

[0161] It should be understood that those skilled in the art can make various modifications, variations, changes, and equivalent embodiments without departing from the spirit and scope of the present invention.

Claims

1. An adhesive film formed from a composition comprising a polymerization product of a monomer mixture containing an aromatic group (meth)acrylic monomer and inorganic particles having a refractive index of 1.5 or greater than 1.5, the adhesive film having a refractive index of 1.55 or greater than 1.55 and a storage modulus of 0.3 MPa or less than 0.3 MPa at 25 °C, wherein the polymerization product has a weight-average molecular weight of 400,000 g / mol to 5,000,000 g / mol, wherein the aromatic group (meth)acrylic monomer comprises a first compound of Formula 2: [Formula 2] wherein X is oxygen; Y is hydrogen or methyl; R 1 is C 1 ~C 10 alkyl, halogen or C 6 ~C 20 aryl; n is an integer from 0 to 5; and R 2 is a single bond, C 1 -C 10 alkylene or C 1 -C 30 monoalkyleneoxy or polyalkyleneoxy.

2. The adhesive film according to claim 1, wherein the adhesive film has a peel strength of 800 g-force / inch or greater than 800 g-force / inch with respect to a glass plate.

3. The adhesive film according to claim 1, wherein the adhesive film has a haze of 1% or less than 1%.

4. The adhesive film according to claim 1, wherein the inorganic particles having a refractive index of 1.5 or greater than 1.5 comprise zirconia.

5. The adhesive film according to claim 1, wherein the inorganic particles having a refractive index of 1.5 or greater than 1.5 are present in the adhesive film in an amount of 5% by weight to 60% by weight.

6. The adhesive film according to claim 1, wherein the inorganic particles having a refractive index of 1.5 or greater than 1.5 have a D50 average particle size of 5 nm to 50 nm.

7. The adhesive film according to claim 1, wherein the composition comprises a curing agent and a photoinitiator.

8. The adhesive film according to claim 7, wherein the curing agent comprises an isocyanate curing agent.

9. The adhesive film according to claim 7, wherein the photoinitiator is present in the adhesive film in an amount of 0.01% by weight to 3% by weight.

10. The adhesive film according to claim 1, wherein the monomer mixture comprises at least one aromatic group (meth)acrylic monomer and a hydroxy group (meth)acrylic monomer.

11. The adhesive film according to claim 10, wherein the aromatic group (meth)acrylic monomer further comprises a second compound of Formula 2: [Formula 2] wherein X is a single bond or C 1 ~C 5 alkylene; Y is hydrogen or methyl; R 1 is C 1 ~C 10 alkyl, halogen or C 6 ~C 20 aryl; n is an integer from 0 to 5; and R 2 is a single bond, C 1 ~C 10 alkylene or C 1 ~C 30 monoalkyleneoxy or polyalkyleneoxy.

12. The adhesive film according to claim 7, wherein the composition comprises 40% by weight to 90% by weight of the polymerization product of the monomer mixture containing the aromatic group (meth)acrylic monomer, 5% by weight to 55% by weight of the inorganic particles having a refractive index of 1.5 or greater than 1.5, 0.01% by weight to 3% by weight of the curing agent, and 0.01% by weight to 3% by weight of the photoinitiator.

13. An optical member comprising the adhesive film according to any one of claims 1 to 12.

14. An optical display device comprising the adhesive film according to any one of claims 1 to 12.

Images