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

Abstract

Provided are an adhesive film, an optical member comprising the adhesive film, and an optical display device comprising the adhesive film, in which the adhesive film comprises inorganic particles having a refractive index of 1.5 or more, and having a diffuse transmittance of 3% or more and a haze of 5% or less at a near-infrared wavelength and a storage modulus of 0.2 MPa or less at-20 DEG C.

Description

Technical Field

[0001] The present invention relates to an adhesive film, an optical member including the adhesive film, and an optical display device including the adhesive film. Background Art

[0002] With the increasing interest in foldable optical displays, there is a need for adhesive films having good foldability. Adhesive films are used to adhesively attach various optical elements to each other in optical display devices.

[0003] Currently, there is a great need for mobile foldable displays for mobile phones and the like. The mobile foldable display is configured to allow a user to write or draw on it using a stylus. In order to correctly recognize the user's writing or drawing, the adhesive film in the display device needs to have a certain range of near-infrared light diffuse transmittance.

[0004] Optical sheet technologies that ensure diffuse transmittance at near-infrared wavelengths have been developed in the art. However, the development of adhesive films that provide good foldability while ensuring diffuse transmittance at near-infrared wavelengths is still insufficient. On the other hand, since the adhesive film may be arranged on the outer edge of the optical display device, the adhesive film must have good impact resistance to protect the panel from external impact.

[0005] The background art of the present invention is disclosed in Japanese Unexamined Patent Publication No. 2013-072951 and the like. Summary of the invention

[0006] Technical issues

[0007] One aspect of the present invention provides an adhesive film having good foldability, low haze, and good diffuse transmittance at near infrared wavelengths.

[0008] Another aspect of the present invention provides an adhesive film having good impact resistance.

[0009] Technical Solution

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

[0011] 1. The adhesive film comprises inorganic particles having a refractive index of 1.5 or more, and has a diffuse transmittance of 3% or more, a haze of 5% or less, and a storage modulus of 0.2 MPa or less at -20°C at a near infrared wavelength.

[0012] 2. In 1, the adhesive film may have a peel strength of 500 gf / inch or more at 25°C.

[0013] 3. In 1 and 2, the adhesive film may have a storage modulus of 0.1 MPa or less at 25°C.

[0014] 4. In 1 to 3, the adhesive film may have a storage modulus of 0.1 MPa or less at 60°C.

[0015] 5. In 1 to 4, the inorganic particles having a refractive index of 1.5 or more may include zinc oxide.

[0016] 6. In 1 to 5, zinc oxide may be present in an amount of 95 wt % or more in the inorganic particles having a refractive index of 1.5 or more.

[0017] 7. In 1 to 6, the zinc oxide may have an average particle size (D50) of 10 nm to 300 nm.

[0018] 8. In 1 to 7, the zinc oxide may include a mixture of zinc oxides having different average particle sizes (D50).

[0019] 9. In 1 to 8, inorganic particles having a refractive index of 1.5 or more may be present in the adhesive film in an amount of 0.01 wt % to 5 wt %.

[0020] 10. In 1 to 9, the adhesive film may further include inorganic particles having a refractive index of less than 1.5.

[0021] 11. In 1 to 10, the inorganic particles having a refractive index less than 1.5 may include silicon dioxide.

[0022] 12. In 1 to 11, the inorganic particles having a refractive index less than 1.5 may be present in the adhesive film in an amount of 0.01 wt % to 20 wt %.

[0023] 13. In 1 to 12, the adhesive film may be formed of an adhesive film composition including inorganic particles having a refractive index of 1.5 or more, inorganic particles having a refractive index of less than 1.5, a polymer of a monomer mixture, and an initiator.

[0024] 14. In 1 to 13, the polymer of the monomer mixture may include: a polymer of a monomer mixture including an alkyl-containing (meth)acrylic monomer and a hydroxyl-containing (meth)acrylic monomer.

[0025] 15. In 1 to 14, the polymer of the monomer mixture may include: a polymer of a monomer mixture including an alkyl group-containing (meth)acrylic monomer, a hydroxyl group-containing (meth)acrylic monomer, and an alkylene glycol group-containing (meth)acrylic monomer.

[0026] 16. In 1 to 15, the monomer mixture may contain 10 wt % to 75 wt % of an alkyl group-containing (meth)acrylic monomer, 2 wt % to 40 wt % of a hydroxyl group-containing (meth)acrylic monomer, and 10 wt % to 60 wt % of an alkylene glycol group-containing (meth)acrylic monomer.

[0027] 17. In 1 to 16, the composition may further contain organic nanoparticles.

[0028] 18. In 1 to 17, the organic nanoparticles may include core-shell organic nanoparticles satisfying Relationship 1:

[0029] [Equation 1]

[0030] Tg(c) <Tg(s),

[0031] Wherein, Tg(c) is the glass transition temperature of the core (unit: °C), and Tg(s) is the glass transition temperature of the shell (unit: °C).

[0032] Another aspect of the present invention relates to an optical component.

[0033] The optical member includes the adhesive film according to the present invention.

[0034] Other aspects of the present invention relate to optical display devices.

[0035] The optical display device includes the adhesive film according to the present invention.

[0036] Beneficial Effects

[0037] The present invention provides an adhesive film having good foldability, low haze, and good diffuse transmittance at near infrared wavelengths.

[0038] The present invention provides an adhesive film having good impact resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a view showing a method of evaluating the peel strength of the adhesive film according to one embodiment of the present invention.

[0040] Figure 2 is a view showing a method of evaluating the impact resistance of the adhesive film according to one embodiment of the present invention. DETAILED DESCRIPTION

[0041] Hereinafter, exemplary embodiments of the present invention will be described in detail below. However, the technology disclosed herein is not limited to the following embodiments described herein, but can be embodied in various forms. It should be understood that the following embodiments are provided in order to fully disclose and enable those skilled in the art to fully understand the present invention.

[0042] The terminology used herein is for the purpose of describing exemplary embodiments and is not intended to be limiting of the present invention.As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0043] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings to facilitate practice by those having ordinary knowledge in the art. It should be understood that the present invention can be implemented in many ways and the present invention is not limited to the following embodiments.

[0044] Herein, "(meth)acryloyl" may refer to acryloyl and / or methacryloyl.

[0045] As used herein, "copolymer" may include a polymer or a resin.

[0046] Herein, the "refractive index" of the inorganic particles is a value measured in the visible spectrum (specifically, at a wavelength of 633 nm). For example, the refractive index of the inorganic particles can be measured by a typical method known to those skilled in the art with reference to a commercially available product catalog.

[0047] Herein, "near infrared wavelengths" refer to wavelengths in the range of 780 nm to 1400 nm.

[0048] Herein, the “diffuse transmittance” may be calculated according to ASTM D 1003. For example, the diffuse transmittance of an adhesive film is calculated by measuring the total transmittance (TT) of a space filled with air and containing no adhesive film. I ) and diffuse transmittance (DT I ), the total transmittance of the space filled with the adhesive film (TT II ) and diffuse transmittance (DT II ), and then the diffuse transmittance of the adhesive film was calculated according to the following equation.

[0049] <Equation>

[0050] Diffuse transmittance of adhesive film = DT II -(TT II -((DT I ) / (TT I )))

[0051] As used herein, "haze" refers to haze measured at a wavelength in the visible spectrum (eg, 380 nm to 780 nm).

[0052] Herein, the “average particle size” of organic nanoparticles refers to the particle size measured using Zetasizer nano-ZS (Malvern Co., Ltd.) in a water-based or organic solvent and represented by a Z average value, and the particle size observed by SEM / TEM.

[0053] Herein, "homopolymer glass transition temperature" may refer to the glass transition temperature (Tg) of a target monomer in a homopolymer phase measured using DSC Discovery (TAInstrument Inc.). Specifically, a homopolymer of a target monomer may be heated to 180°C at 20°C / min, slowly cooled to -100°C at the same rate, and heated again to 100°C at 10°C / min to obtain an endothermic transition curve. Then, the inflection point of the endothermic transition curve may be determined as the glass transition temperature.

[0054] As used herein for expressing a specific numerical range, “X to Y” means “X≤ and ≤Y”.

[0055] The present invention relates to an adhesive film having good foldability while satisfying diffuse transmittance in a certain range of near-infrared wavelengths and having low haze. The present invention also relates to an adhesive film having good impact resistance.

[0056] Hereinafter, an adhesive film according to one embodiment of the present invention will be described.

[0057] The adhesive film according to the embodiment has a diffuse transmittance of 3% or more at a near infrared wavelength, a haze of 5% or less, and a storage modulus of 0.2 MPa or less at -20°C.

[0058] The adhesive film has a diffuse transmittance of 3% or more at a near-infrared wavelength. Within this range, when the adhesive film is fixed and used on a mobile display (such as a mobile phone, etc.), the mobile display can be smoothly driven when writing or drawing thereon with a pen, etc. Specifically, the diffuse transmittance of the adhesive film can be 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49 %, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89% or 90%, more specifically greater than 3% and less than or equal to 90%, and more specifically 3.2% to 10%.

[0059] The adhesive film has a haze of 5% or less. Within this range, when applied to an optical display device, the adhesive film does not affect image display. Specifically, the haze of the adhesive film can be 0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, 5. .6%, 2.7%, 2.8%, 2.9%, 3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9% or 5%, more specifically 0% to 5%, and more specifically 0.1% to 3%.

[0060] The adhesive film has a storage modulus of 0.2 MPa or less at -20° C. Within this range, the adhesive film may provide good foldability at low temperature, room temperature, and high temperature. Specifically, the storage modulus of the adhesive film at -20°C may be 0.001 MPa, 0.005 MPa, 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 or 0.2 MPa, more specifically 0.001 MPa to 0.2 MPa, and even more specifically 0.1 MPa to 0.2 MPa.

[0061] The adhesive film is formed from the adhesive film composition described below, thereby providing a diffuse transmittance of 3% or more and a haze of 5% or less at a near-infrared wavelength, while achieving the above-mentioned storage modulus at -20°C. In one embodiment, the adhesive film may include a cured product of the composition. The adhesive film composition according to the present invention will be described in detail below.

[0062] The adhesive film composition includes inorganic particles having a refractive index of 1.5 or more.

[0063] Using inorganic particles having a refractive index of 1.5 or more, the adhesive film can easily achieve a diffuse transmittance of 3% or more at a near-infrared wavelength.

[0064] In one embodiment, the inorganic particles may have a refractive index of 1.5 to 2.5 (e.g., 1.8 to 2.3, 2.0 to 2.5, or 1.9 to 2.2). Within these ranges, the adhesive film can easily achieve a diffuse transmittance of 3% or more and a haze of 5% or less at near-infrared wavelengths. This is caused by the refractive index difference between the inorganic particles and the adhesive film matrix (formed by curing the remaining components other than the inorganic particles having a refractive index of 1.5 or more) in the adhesive film composition described below.

[0065] Inorganic particles having a refractive index of 1.5 or more are embedded in the adhesive film matrix, and the refractive index difference between the inorganic particles having a refractive index of 1.5 or more and the adhesive film matrix can be in the range of 0.4 to 1.1, such as 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0 or 1.1, such as 0.6 to 1.0. Within this range, the adhesive film can easily achieve diffuse transmittance and haze at near-infrared wavelengths according to the present invention. The "adhesive film matrix" is a cured product formed by curing the remaining components of the adhesive film composition except the inorganic particles having a refractive index of 1.5 or more and the inorganic particles having a refractive index of less than 1.5 as described below.

[0066] The composition according to the present invention contains zinc oxide as inorganic particles having a refractive index of 1.5 or more. When contained in an adhesive film matrix that achieves the storage modulus at -20°C described below, zinc oxide is particularly suitable for achieving a diffuse transmittance of 3% or more and a haze of 5% or less at near infrared wavelengths without affecting the storage modulus at -20°C.

[0067] The zinc oxide may be zinc oxide alone or an aggregate containing zinc oxide and trace amounts of impurities.

[0068] In the inorganic particles having a refractive index of 1.5 or more, zinc oxide may be present in an amount of 95 wt % or more (eg, 95 wt % to 100 wt %, for example, 100 wt %). Within this range, the adhesive film may sufficiently achieve the above-mentioned inventive effects.

[0069] The inorganic particles with a refractive index of 1.5 or more can have a spherical, amorphous shape, etc., and the average particle size (D50) can be 10nm to 300nm (specifically, 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm, 200nm, 210nm, 220nm, 230nm, 240nm, 250nm, 260nm, 270nm, 280nm, 290nm, 300nm) or 30nm to 200nm. Within this range, the adhesive film can suppress the increase in haze and the deterioration of foldability. In this article, "average particle size (D50)" can be measured by typical methods known to those skilled in the art. For example, the average particle diameter (D50) indicates a particle diameter corresponding to 50% in a weight distribution of inorganic particles analyzed by weight accumulation using a particle size analyzer.

[0070] In one embodiment, the inorganic particles having a refractive index of 1.5 or more may consist of inorganic particles having an average particle diameter (D50) of 10 nm to 300 nm, specifically 120 nm to 200 nm.

[0071] In another embodiment, the inorganic particles having a refractive index of 1.5 or more can be a mixture of two or more types of inorganic particles with different average particle sizes (D50). For example, the inorganic particles having a refractive index of 1.5 or more can be a mixture of first inorganic particles having an average particle size (D50) of 10nm to 300nm, specifically 30nm to 200nm, more specifically 120nm to 200nm, and an average particle size (D50) of 10nm to 300nm, specifically greater than or equal to 10nm and less than 100nm. In the inorganic particles with a refractive index of 1.5 or more, the first inorganic particles and the second inorganic particles may be present in a weight ratio (first inorganic particles to second inorganic particles) of 1:0.1 to 1:3 (e.g., 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9, 1:3) or 1:0.5 to 1:2.

[0072] The inorganic particles having a refractive index of 1.5 or more may not be surface treated or may be surface treated to improve compatibility with other organic components in the adhesive film composition.The surface treatment of the inorganic particles having a refractive index of 1.5 or more may be performed by any typical method known to those skilled in the art.

[0073] The inorganic particles having a refractive index of 1.5 or more may be present in the adhesive film in an amount of 0.01 wt % to 5 wt % (e.g., 0.01 wt %, 0.05 wt %, 0.1 wt %, 0.2 wt %, 0.3 wt %, 0.4 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 %, 3 wt %, 4 wt % or 5 wt %), specifically 0.05 wt % to 2 wt %. Within this range, the adhesive film can easily achieve the above-mentioned diffuse transmittance at near infrared wavelengths, haze and storage modulus at -20°C.

[0074] The inorganic particles having a refractive index of 1.5 or more may be present in an amount of 0.01 to 2 parts by weight (e.g., 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9 or 2 parts by weight), e.g., 0.05 to 0.5 parts by weight. Within this range, the adhesive film can easily achieve the above-mentioned diffuse transmittance at near-infrared wavelengths, haze, and storage modulus at -20°C.

[0075] The adhesive film composition further includes a polymer of the monomer mixture and an initiator.

[0076] The composition comprising the polymer of the monomer mixture and an initiator may be cured to form an adhesive film matrix.

[0077] The monomer mixture may include an alkyl group-containing (meth)acrylic acid monomer and a hydroxyl group-containing (meth)acrylic acid monomer.

[0078] The alkyl-containing (meth) acrylic acid monomer is used to promote the formation of an adhesive film matrix. In one embodiment, the alkyl-containing (meth) acrylic acid monomer may include an unsubstituted linear or branched C1 to C2 alkyl group at its ester site. 10 Alkyl (meth) acrylate. For example, the alkyl-containing (meth) acrylic acid monomer may include at least one selected from the following: 2-ethylhexyl (meth) acrylate, n-butyl (meth) acrylate, isooctyl (meth) acrylate, propyl (meth) acrylate, tert-butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate and decyl (meth) acrylate, preferably at least one selected from the following: 2-ethylhexyl (meth) acrylate, n-butyl (meth) acrylate and isooctyl (meth) acrylate, more preferably 2-ethylhexyl (meth) acrylate.

[0079] The alkyl-containing (meth)acrylic monomer may have a homopolymer glass transition temperature of -80° C. to -20° C., specifically -80° C. to -40° C. Within this range, the adhesive film may ensure good foldability at low temperatures and under high temperature / high humidity conditions.

[0080] In the monomer mixture, the alkyl-containing (meth)acrylic monomer may be present in an amount of 10 wt % to 75 wt %, preferably 10 wt % to 70 wt % or 15 wt % to 60 wt %. Within this range, the adhesive film may have good flexural reliability at low temperatures and under high temperature / high humidity conditions.

[0081] The hydroxyl-containing (meth) acrylic acid monomer is used to provide peel strength to the adhesive film. The hydroxyl-containing (meth) acrylic acid monomer may include C1 to C2 containing at least one hydroxyl group at its ester site. 10 (Meth)acrylate. For example, the hydroxyl-containing (meth)acrylic acid monomer may include at least one selected from the group consisting of 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate, but is not limited thereto.

[0082] The hydroxyl-containing (meth)acrylic monomer may have a homopolymer glass transition temperature of -70 to 0° C., preferably -60 to -10° C., more preferably -50 to -20° C. Within this range, the adhesive film may achieve improved peel strength and foldability.

[0083] In the monomer mixture, the hydroxyl-containing (meth) acrylic monomer may be present in an amount of 2 wt % to 40 wt % (e.g., 10 wt % to 30 wt %, 2 wt % to 20 wt % or 5 wt % to 20 wt %). Within these ranges, the adhesive film may achieve improvements in bonding strength and durability.

[0084] The monomer mixture may also include an alkylene glycol group-containing (meth) acrylic acid monomer. The alkylene glycol group-containing (meth) acrylic acid ester includes an alkylene glycol group, thereby easily providing foldability to the adhesive film. In this article, "alkylene glycol group" means (C2 to C4 alkylene)-O-.

[0085] The (meth) acrylic monomer containing an alkylene glycol group may have a homopolymer glass transition temperature of -90°C to -55°C, preferably -90°C to -60°C, more preferably -75°C to -60°C. Within this range, the adhesive film may have a low modulus at low temperatures while improving foldability at low temperatures. The (meth) acrylate containing an alkylene glycol group may include a monofunctional acrylate having an oxyethylene group (-CH2CH2O-) or an oxypropylene group (-CH2CH2CH2O-), preferably an oxyethylene group.

[0086] The (meth) acrylic acid monomer containing alkylene glycol groups can include, for example, ether (meth) acrylates containing 1 mole or more, for example, 2 to 20 moles of ethylene glycol. Specifically, ethylene glycol-containing (meth) acrylates can include at least one selected from the following: poly (ethylene glycol) methyl ether (meth) acrylates containing 6 to 13 moles of ethylene glycol, poly (ethylene glycol) ethyl hexyl ether (meth) acrylates containing 2 to 10 moles of ethylene glycol, and poly (ethylene glycol) octyl ether (meth) acrylates containing 2 to 20 moles of ethylene glycol. Preferably, alkylene glycol-containing (meth) acrylates can include at least one selected from the following: di (ethylene glycol) 2-ethyl hexyl ether (meth) acrylates, tri (ethylene glycol) 2-ethyl hexyl ether (meth) acrylates and di (ethylene glycol) octyl ether (meth) acrylates.

[0087] In the monomer mixture, the (meth)acrylic monomer containing an alkylene glycol group may be present in an amount of 10 wt % to 60 wt %, preferably 20 wt % to 60 wt %, more preferably 20 wt % to 50 wt %. Within this range, the adhesive film may have improved repeated foldability at low temperatures.

[0088] In one embodiment, the alkyl-containing (meth) acrylic monomer, the hydroxyl-containing (meth) acrylic monomer, and the alkylene glycol-containing (meth) acrylic monomer may be present in the monomer mixture in a total amount of 98 wt % or more, for example, 98 wt % to 100 wt %, for example, 100 wt %. Within this range, the adhesive film can easily achieve the effects of the present invention.

[0089] The monomer mixture may further include another comonomer in addition to the alkyl group-containing (meth)acrylic monomer, the hydroxyl group-containing (meth)acrylic monomer, and the alkylene glycol group-containing (meth)acrylic monomer. The comonomer may be included in the polymer to provide an additional effect to the adhesive film.

[0090] The comonomer refers to a monomer other than the above-mentioned monomers, and may include at least one selected from the group consisting of an amine-containing monomer, an alkoxy-containing monomer, a phosphoric acid-containing monomer, a sulfonic acid-containing monomer, a phenyl-containing monomer, a silane-containing monomer, a carboxylic acid-containing monomer, and an amide-containing monomer.

[0091] The amino-containing monomer may be an amino-containing (meth)acrylic monomer such as monomethylaminoethyl acrylate, monoethylaminoethyl acrylate, monomethylaminopropyl acrylate, monoethylaminopropyl acrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, N-tert-butylaminoethyl acrylate, acryloxyethyltrimethylammonium chloride, etc., but is not limited thereto.

[0092] The alkoxy-containing monomer may include 2-methoxyethyl (meth)acrylate, 2-methoxypropyl (meth)acrylate, 2-ethoxypropyl (meth)acrylate, 2-butoxypropyl (meth)acrylate, 2-methoxypentyl (meth)acrylate, 2-ethoxypentyl (meth)acrylate, 2-butoxyhexyl (meth)acrylate, 3-methoxypentyl (meth)acrylate, 3-ethoxypentyl (meth)acrylate and 3-butoxyhexyl (meth)acrylate, but is not limited thereto.

[0093] The phosphoric acid group-containing monomer may be a phosphoric acid group-containing acrylic monomer such as 2-methacryloyloxyethyl diphenyl phosphate, trimethacryloyloxyethyl phosphate, triacryloyloxyethyl phosphate, etc., but is not limited thereto.

[0094] The sulfonic acid group-containing monomer may be a sulfonic acid group-containing acrylic acid monomer such as sodium sulfopropyl acrylate, sodium 2-sulfoethyl acrylate, sodium 2-acrylamide-2-methylpropane sulfonate, etc., but is not limited thereto.

[0095] The phenyl group-containing monomer may be a phenyl group-containing acrylic vinyl monomer such as p-tert-butylphenyl acrylate, o-biphenyl acrylate, and phenoxyethyl acrylate, but is not limited thereto.

[0096] The silyl group-containing monomer may be a silyl group-containing vinyl monomer such as 2-acetoacetoxyethyl acrylate, vinyl trimethoxysilane, vinyl triethoxysilane, vinyl tri(2-methoxyethyl)silane, vinyl triacetoxysilane, and acryloxypropyl trimethoxysilane, but is not limited thereto.

[0097] The carboxyl group-containing monomer may include acrylic acid, 2-carboxyethyl acrylate, 3-carboxypropyl acrylate, 4-carboxybutyl acrylate, itaconic acid, crotonic acid, maleic acid, fumaric acid, and maleic anhydride, but is not limited thereto.

[0098] The amide group-containing monomer may include acrylamide, N-methylacrylamide, N-methylolacrylamide, N-methoxymethylacrylamide, N,N-methylenebisacrylamide, N-hydroxyethylacrylamide, N,N-diethylacrylamide, etc., but is not limited thereto.

[0099] In the monomer mixture, the comonomer may be present in an amount of 30 wt% or less, preferably 0 wt% to 30 wt%.The comonomer is used to control adhesion to an adherend and to provide optical properties.

[0100] The initiator is used to form an adhesive film by curing the adhesive composition or to polymerize the remaining monomers after the monomer mixture in the adhesive film composition is polymerized. The initiator may include a photoinitiator, preferably a photo radical initiator.

[0101] The photoinitiator may be selected from any photoinitiator capable of inducing polymerization of the above-mentioned free radical polymerizable compound during curing by irradiation with light, etc. For example, the photoinitiator may be benzoin, hydroxyketone, aminoketone or phosphine oxide photoinitiator. Specifically, the photoinitiator may include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone compounds (such as 2,2-dimethoxy-2-phenylacetophenone, 2,2'-diethoxyacetophenone, 2,2'-dibutoxyacetophenone, 2-hydroxy-2-methylpropiophenone, p-tert-butyltrichloroacetophenone, p-tert-butyldichloroacetophenone, 4-chloroacetophenone, 2,2'-dichloro-4-phenoxyacetophenone, etc., dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone), 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butane-1-one, 1-hydroxy-2-methyl-1-phenylpropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butane-1-one, etc. The invention also includes 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinyl-propan-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzophenone, p-phenylbenzophenone, 4,4-bisdiethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoate, oligo[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone] and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, but is not limited thereto.

[0102] The initiator may be present in an amount of 0.0001 to 5 parts by weight, specifically 0.001 to 3 parts by weight, more specifically 0.001 to 1 part by weight, relative to 100 parts by weight of the monomer mixture. Within this range, the initiator allows the adhesive composition to be completely cured, can prevent the deterioration of the transmittance of the adhesive film due to residual initiator, can reduce bubble generation, and can show good reactivity.

[0103] The adhesive film composition may further include inorganic particles having a refractive index of less than 1.5.

[0104] In one embodiment, the inorganic particles having a refractive index less than 1.5 can improve the impact resistance of the adhesive film, rather than improving the diffuse transmittance of the adhesive film at near-infrared wavelengths. In one embodiment, the adhesive film can have an initial dent (dent) formation height of 5 cm or more, for example 5 cm to 10 cm, as determined by the following impact resistance test. Within this range, when stacked on a panel, the adhesive film can prevent damage to the panel including the light-emitting device due to external impact. In this article, "impact resistance" can be measured by the following method.

[0105] The inorganic particles having a refractive index of less than 1.5 may have a refractive index of greater than or equal to 1.3 and less than 1.5 (e.g., 1.3, 1.31, 1.32, 1.33, 1.34, 1.35, 1.36, 1.37, 1.38, 1.39, 1.4, 1.41, 1.42, 1.43, 1.44, 1.45, 1.46, 1.47, 1.48, 1.49) or 1.3 to 1.49. Within this range, the inorganic particles do not affect the diffuse transmittance and haze of the adhesive film at near infrared wavelengths.

[0106] In one embodiment, the inorganic particles having a refractive index less than 1.5 may include silicon dioxide. For example, the silicon dioxide may include fumed silica, hollow silica, core-shell silica, and the like.

[0107] The inorganic particles having a refractive index of less than 1.5 may have a spherical or amorphous shape and may have an average particle size (D50) smaller than that of the inorganic particles having a refractive index of 1.5 or greater. Therefore, the inorganic particles having a refractive index of less than 1.5 may improve the impact resistance of the adhesive film without affecting the diffuse transmittance of the adhesive film at near-infrared wavelengths.

[0108] On the contrary, relative to the inorganic particles with a refractive index greater than 1.5, the inorganic particles with a refractive index less than 1.5 may be present in excess in the adhesive film. For example, in the adhesive film, the inorganic particles with a refractive index less than 1.5 may be present in an amount of 10 to 30 times (specifically, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30 times) the amount of the inorganic particles with a refractive index of 1.5 or more, specifically 20 to 30 times.

[0109] Specifically, the inorganic particles having a refractive index of less than 1.5 can have an average particle size (D50) of 1 nm to 50 nm (e.g., 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, 30 nm, 31 nm, 32 nm, 33 nm, 34 nm, 35 nm, 36 nm, 37 nm, 38 nm, 39 nm, 40 nm, 41 nm, 42 nm, 43 nm, 44 nm, 45 nm, 46 nm, 47 nm, 48 nm, 49 nm, 50 nm) or 5 nm to 30 nm. Within this range, the inorganic particles having a refractive index of less than 1.5 can ensure their inherent effects.

[0110] In the adhesive film, the inorganic particles having a refractive index of less than 1.5 may be present in an amount of 0.01 wt % to 20 wt % (e.g., 0.01 wt %, 0.05 wt %, 0.1 wt %, 0.2 wt %, 0.3 wt %, 0.4 wt %, 0.5 wt %, 0.6 wt %, 0.7 wt %, 0.8 wt %, 0.9 wt %, 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 %, 15 wt %, 16 wt %, 17 wt %, 18 wt %, 19 wt %, 20 wt %), 1 wt % to 10 wt %, 1 wt % to 5 wt % or 2 wt % to 8 wt %. Within this range, the inorganic particles may improve the impact resistance of the adhesive film and may ensure the effect of the invention.

[0111] The inorganic particles having a refractive index of less than 1.5 may be present in an amount of 0.1 to 10 parts by weight (e.g., 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, 10) or 1 to 5 parts by weight relative to 100 parts by weight of the monomer mixture. Within this range, the inorganic particles may improve the impact resistance of the adhesive film and may ensure the inventive effect.

[0112] The adhesive film composition may further include organic nanoparticles.

[0113] Organic nanoparticles can further improve the reliability of the adhesive film at high temperatures by increasing the storage modulus of the adhesive film at high temperatures to prevent delamination, slight warping and / or bubble generation at high temperatures. The organic nanoparticles have a high glass transition temperature, thereby improving the modulus of the adhesive film at high temperatures.

[0114] The average particle size of the organic nanoparticles may be 10 nm to 400 nm, specifically 10 nm to 300 nm, more specifically 30 nm to 280 nm, and even more specifically 50 nm to 280 nm. Within this average particle size range, the organic nanoparticles do not affect the foldability of the adhesive film and can ensure good transparency of the adhesive film by ensuring a total transmittance of about 90% or more in the visible spectrum.

[0115] The refractive index difference between the organic nanoparticles and the polymer of the monomer mixture including the (meth)acrylic monomer may be 0.1 or less, specifically 0.0 to 0.05, more specifically 0.0 to 0.02. Within this range, the adhesive film may exhibit good transparency.

[0116] In one embodiment, the refractive index of the organic nanoparticles may be 1.35 to 1.70, specifically 1.40 to 1.60. Within this range, the adhesive film may exhibit good transparency.

[0117] The organic nanoparticles may have a core-shell structure or a simple structure such as bead-type nanoparticles, but are not limited thereto. In one embodiment, the organic nanoparticles may have a core-shell structure, wherein the core and the shell satisfy the following relationship 1. That is, the organic nanoparticles may include nanoparticles wherein the core and the shell are formed of organic materials. Using organic nanoparticles having a core-shell structure, the adhesive film may show good foldability and a balance between elasticity and flexibility.

[0118] [Equation 1]

[0119] Tg(c) <Tg(s)

[0120] Wherein, Tg(c) is the glass transition temperature of the core (unit: °C), and Tg(s) is the glass transition temperature of the shell (unit: °C).

[0121] In this article, the term "shell" refers to the outermost layer of the organic nanoparticle. The core can be a spherical particle. In some embodiments, the core can include an additional layer surrounding the spherical particle, provided that the core has a glass transition temperature that satisfies the above relationship.

[0122] Specifically, the core may have a glass transition temperature of -150°C to 10°C, specifically -150°C to -5°C, more specifically -150°C to -20°C. Within this range, the adhesive film may have good viscoelasticity at low temperatures and / or at room temperature. The core may include at least one selected from poly(alkyl acrylate), polysiloxane, or polybutadiene having a glass transition temperature within this range.

[0123] The poly(alkyl acrylate) may include at least one selected from the group consisting of poly(methyl acrylate), poly(ethyl acrylate), poly(propyl acrylate), poly(butyl acrylate), poly(isopropyl acrylate), poly(hexyl acrylate), poly(hexyl methacrylate), poly(ethylhexyl acrylate), and poly(ethylhexyl methacrylate), and polysiloxane, but is not limited thereto.

[0124] The polysiloxane can be, for example, an organosiloxane (co)polymer. The organosiloxane (co)polymer can be an uncrosslinked or crosslinked organosiloxane (co)polymer. The crosslinked organosiloxane (co)polymer can be used to ensure impact resistance and coloring ability. Specifically, the crosslinked organosiloxane (co)polymer can include crosslinked dimethylsiloxane, methylphenylsiloxane, biphenylsiloxane or a mixture thereof. Using a copolymer of two or more organosiloxanes, the nanoparticle can have a refractive index of 1.41 to 1.50.

[0125] The crosslinked state of the organosiloxane (co)polymer can be determined based on the degree of dissolution in a variety of organic solvents. As the degree of crosslinking of the organosiloxane (co)polymer increases, the degree of dissolution of the organosiloxane (co)polymer decreases. The solvent used to determine the crosslinked state can include acetone, toluene, etc. Specifically, the organosiloxane (co)polymer can have a portion that is insoluble in acetone or toluene. The organosiloxane copolymer can contain 30% or more insoluble matter in toluene.

[0126] The organosiloxane (co)polymer may also include an alkyl acrylate cross-linked polymer. The alkyl acrylate cross-linked polymer may include methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, etc. For example, the alkyl acrylate cross-linked polymer may be n-butyl acrylate or 2-ethylhexyl acrylate with a low glass transition temperature.

[0127] Specifically, the shell can have a glass transition temperature of 15°C to 150°C, specifically 35°C to 150°C, more specifically 50°C to 140°C. Within this range, the organic nanoparticles can show good dispersion in the acrylic copolymer. The shell can include a poly(alkyl methacrylate) having a glass transition temperature within this range. For example, the shell can include at least one selected from the group consisting of poly(methyl methacrylate) (PMMA), poly(ethyl methacrylate), poly(propyl methacrylate), poly(butyl methacrylate), poly(isopropyl methacrylate), poly(isobutyl methacrylate), and poly(cyclohexyl methacrylate), but is not limited thereto.

[0128] In organic nanoparticles, the core may be present in an amount of 30 wt % to 99 wt %, specifically 40 wt % to 95 wt %, more specifically 50 wt % to 90 wt %. Within these ranges, the adhesive film may exhibit good foldability over a wide temperature range. In organic nanoparticles, the shell may be present in an amount of 1 wt % to 70 wt %, specifically 5 wt % to 60 wt %, more specifically 10 wt % to 50 wt %. Within these ranges, the adhesive film may have good foldability over a wide temperature range.

[0129] The organic nanoparticles may optionally be present in the adhesive film in an amount of 20 wt % or less, specifically 0.1 wt % to 20 wt %, specifically 0.5 wt % to 12 wt %, specifically 0.5 wt % to 8 wt %. Within these ranges, the organic nanoparticles may ensure good properties in terms of the modulus of the adhesive film at high temperatures, the foldability of the adhesive film at room temperature and high temperatures, and the viscoelasticity of the adhesive film at low temperatures and / or room temperatures.

[0130] The organic nanoparticles may optionally be present in an amount of 10 parts by weight or less, for example 0.01 to 5 parts by weight, for example 0.01 to 2 parts by weight, relative to 100 parts by weight of the monomer mixture. Within this range, the adhesive film may have improved foldability at high temperatures.

[0131] The organic nanoparticles may be prepared by typical emulsion polymerization, suspension polymerization or solution polymerization.

[0132] The adhesive film composition may further include a cross-linking agent.

[0133] The crosslinking agent may improve the mechanical strength of the adhesive film by increasing the degree of crosslinking of the composition.

[0134] The crosslinking agent may include a multifunctional (meth)acrylate that is curable by actinic radiation. For example, the crosslinking agent may include a bifunctional acrylate such as 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, neopentyl glycol adipate di(meth)acrylate, dicyclopentenyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified di(meth)acrylate, di(meth)acryloyloxyethyl isocyanurate, allylated cyclohexyl di(meth)acrylate, tricyclodecane dimethanol (meth)acrylate, dihydroxymethyl dicyclopentane di(meth)acrylate, ethylene oxide-modified hexahydrophthalic acid di(meth)acrylate, tricyclodecane dimethanol (meth)acrylate, neopentyl glycol modified trimethyl propane di(meth)acrylate, adamantane di(meth)acrylate, 9,9-bis[4-(2-propylene)] trifunctional acrylates such as trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, trifunctional urethane (meth)acrylate, tri(meth)acryloyloxyethyl isocyanurate, etc.; tetrafunctional acrylates such as diglycerol tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, etc.; pentafunctional acrylates such as dipentaerythritol penta(meth)acrylate, etc.; and hexafunctional acrylates such as dipentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, and urethane (meth)acrylate (e.g., the reaction product of an isocyanate monomer and trimethylolpropane tri(meth)acrylate), etc., but are not limited thereto.

[0135] The crosslinking agent may be present in an amount of 0.001 to 5 parts by weight, specifically 0.003 to 3 parts by weight, specifically 0.005 to 1 part by weight, relative to 100 parts by weight of the monomer mixture or the polymer of the monomer mixture. Within this range, the adhesive film may exhibit good peel strength and improved reliability.

[0136] The adhesive film composition may further include additives. The additives may include typical additives used in typical adhesive film compositions and known to those skilled in the art. For example, the additives may include at least one type selected from the following: pigments, UV absorbers, leveling agents, antistatic agents, etc., but are not limited thereto.

[0137] The adhesive film may have a peel strength of 500 gf / inch or more, for example, 500 gf / inch to 3,000 gf / inch at 25°C. Within this range, the adhesive film may ensure good foldability. In this article, "peel strength" refers to T-peel strength. T-peel strength can be measured by the method in the following experimental example, wherein the substrate can be a glass plate, such as an alkali-free glass plate.

[0138] The adhesive film may have a modulus of 0.1 MPa or less, for example, 0.05 MPa to 0.1 MPa at 25° C. Within this range, the adhesive film may have good flexibility at room temperature and good bending reliability at room temperature. The adhesive film may have a modulus of 0.1 MPa or less, for example, 0.05 MPa to 0.1 MPa at 60° C.

[0139] The adhesive film may have a haze of 2% or less, specifically 0.1% to 1%, and a total transmittance of 90% or more, specifically 95% to 99%, in the visible spectrum (e.g., at a wavelength of 380nm to 780nm). Within this range, the adhesive film may have good optical transparency to be used in an optical display device.

[0140] The adhesive film may have a thickness of 10 μm to 300 μm, specifically 20 μm to 100 μm. Within this range, the adhesive film may be used for an optical display device.

[0141] The adhesive film composition can be prepared by partially polymerizing the monomer mixture using an initiator and then adding another initiator. The composition may also include the above-mentioned organic nanoparticles, a crosslinking agent, an additive, and the like. Partial polymerization may include solution polymerization, suspension polymerization, photopolymerization, bulk polymerization, or emulsion polymerization. Specifically, solution polymerization may be performed by adding an initiator to the monomer mixture and then heating to 50°C to 100°C. The initiator may include an acetophenone initiator, including 2,2-dimethoxy-2-phenylacetophenone; and a photopolymerization initiator, such as 1-hydroxycyclohexyl phenyl ketone, and the like. Partial polymerization can achieve a viscosity of 300 cP to 50,000 cP, specifically 500 cP to 9,000 cP at 25°C.

[0142] The adhesive film is a pressure sensitive adhesive film and can be prepared by typical methods. For example, the adhesive film composition can be prepared by coating the adhesive film composition on a release film and then curing. Curing can include irradiating the adhesive film with a wavelength of 300nm to 400nm and a dosage of 400mJ / cm in the absence of oxygen using a low pressure lamp. 2 Up to 3,000mJ / cm 2 of light irradiation.

[0143] An optical component according to one embodiment of the present invention comprises an optical film and an adhesive film formed on at least one surface of the optical film, wherein the adhesive film comprises an adhesive film according to an embodiment of the present invention. Therefore, the optical component exhibits good bending properties and / or good foldability, and can therefore be used in a flexible display.

[0144] In one embodiment, the optical film provides optical functions to the display device, for example, polarization, optical compensation, display quality improvement and / or conductivity. Examples of optical films may include window films, windows, polarizing plates, color filters, delay films, elliptically polarizing films, reflective polarizing films, anti-reflection films, compensation films, brightness enhancement films, orientation films, light diffusion films, glass anti-shatter films, surface protection films, OLED device barrier layers, plastic LCD substrates, and transparent electrode films (including indium tin oxide (ITO), fluorine tin oxide (FTO), aluminum-doped zinc oxide (AZO), carbon nanotubes (CNT), Ag nanowires, graphene, etc.). Those skilled in the art can easily manufacture these optical films.

[0145] For example, the touch pad may be attached to a window film or an optical film via an adhesive film, thereby forming a touch panel. Alternatively, the adhesive film may be applied to a typical polarizing film in the related art.

[0146] In another embodiment, the optical film is an optically transparent film, and the optical member including the optical film and the adhesive film can serve as a support layer for the display element. For example, the display element may include a window film, etc. The window film may include an optical member and a window coating (e.g., a silicone coating) formed on the optical member. Specifically, the optical film may have a total transmittance of 90% or more in the visible spectrum, and may be formed by at least one resin selected from the following: a cellulose resin, including cellulose triacetate, etc.; a polyester resin, including polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, etc.; a polycarbonate resin; a polyimide resin; a polystyrene resin; a polyacrylate resin, including poly (methyl methacrylate), etc.; a cycloolefin polymer resin; an acrylic resin; and a polyamide resin. The optical film may have a thickness of 10 μm to 100 μm, specifically 20 μm to 75 μm, more specifically 30 μm to 50 μm. Within this range, the optical member can be used as a supporting layer of a display element.

[0147] The optical display device according to the present invention includes the adhesive film according to the present invention. The optical display device may include an organic light emitting diode display, a liquid crystal display, etc. The optical display device may include a flexible display. In other embodiments, the optical display may include a non-flexible display.

[0148] Invention Mode

[0149] Next, the present invention will be described in more detail with reference to some examples. It should be understood that these examples are provided for illustrative purposes only and should not be considered in any way as limiting the present invention.

[0150] Preparation Example: Preparation of Organic Nanoparticles

[0151] 100 parts by weight of a monomer mixture as listed in Table 1 was prepared and fully mixed with 0.005 parts by weight of a photoinitiator (Irgacure 651) in a reactor. After replacing the dissolved oxygen in the reactor with nitrogen, the monomer mixture was partially polymerized by irradiating with UV light for several minutes under a low-pressure mercury lamp, thereby preparing a composition of a partial (meth)acrylic copolymer containing the monomer mixture. As shown in Table 1, 0.3 parts by weight of a photoinitiator (Irgacure 651) and 0.2 parts by weight of zinc oxide (ZnO, average particle size (D50): 150 nm, refractive index: 2.0) were added to the composition and mixed therewith, thereby preparing an adhesive film composition.

[0152] The adhesive film composition was coated on a polyethylene terephthalate (PET) release film and covered with the PET release film, and then irradiated with a dose of 2,000 mJ / cm 2 The PET film, the adhesive film and the adhesive sheet of the PET film were prepared by irradiating the PET film with UV light.

[0153] Example 2

[0154] An adhesive sheet was prepared in the same manner as in Example 1, except that, after partial polymerization, an adhesive film was prepared by adding 0.3 parts by weight of a photoinitiator (Irgacure 651), 0.1 parts by weight of zinc oxide (ZnO, average particle size (D50): 150 nm, refractive index: 2.0), 0.1 parts by weight of zinc oxide (ZnO, average particle size (D50): 40 nm, refractive index: 2.0) and 5 parts by weight of silicon dioxide (SiO2, average particle size (D50): 15 nm, refractive index: 1.46).

[0155] Example 3

[0156] An adhesive sheet was prepared in the same manner as in Example 2, except that it contained 0.2 parts by weight of zinc oxide (ZnO, average particle size (D50): 120 nm, refractive index: 2.0) and 5 parts by weight of silicon dioxide (SiO2, average particle size (D50): 15 nm, refractive index: 1.46).

[0157] Example 4

[0158] Organic nanoparticles were prepared by emulsion polymerization. Organic nanoparticles including 65 wt% of a poly(butyl acrylate) core and 35 wt% of a poly(methyl methacrylate) shell and having an average particle size (D50) of 100 nm and a refractive index of 1.48 were prepared.

[0159] An adhesive sheet was prepared in the same manner as in Example 2, except that it contained 0.2 parts by weight of zinc oxide (ZnO, average particle size (D50): 150 nm, refractive index: 2.0), 5 parts by weight of silicon dioxide (SiO2, average particle size (D50): 15 nm, refractive index: 1.46) and 0.1 parts by weight of organic nanoparticles (average particle size (D50): 100 nm, refractive index: 1.48).

[0160] Comparative Examples 1 and 2

[0161] An adhesive sheet was prepared in the same manner as in Example 2, except that the components of the adhesive film composition were changed as listed in Table 1.

[0162] Comparative Example 3

[0163] An adhesive sheet was prepared in the same manner as in Example 1, except that antimony tin oxide (ATO, average particle size: 40 nm, refractive index: 1.69) was used instead of zinc oxide, and the content of each component was changed as listed in Table 1.

[0164] Comparative Example 4

[0165] An adhesive sheet was prepared in the same manner as in Example 1, except that magnesium oxide (MgO, average particle size: 100 nm, refractive index: 1.74) was used instead of zinc oxide, and the content of each component was changed as listed in Table 1.

[0166] Comparative Example 5

[0167] In the same manner as in Example 4, organic nanoparticles were prepared.

[0168] An adhesive sheet was prepared in the same manner as in Example 1, except that organic nanoparticles (refractive index: 1.48, average particle diameter (D50): 100 nm) were used instead of zinc oxide.

[0169] Detailed information of the adhesive films prepared in Examples and Comparative Examples is shown in Table 1. The properties listed in Table 1 were evaluated for the adhesive sheets of Examples and Comparative Examples.

[0170] (1) Diffuse transmittance at near infrared wavelength (unit: %): Adhesive films were obtained by removing the PET release films from both sides of each adhesive sheet prepared in Examples and Comparative Examples. The transmittance of the adhesive film at near infrared wavelength was measured using a UV spectrometer and an integrating sphere according to ASTM D 1003, and then the diffuse transmittance at near infrared wavelength was calculated according to the above equation.

[0171] (2) Haze (unit: %): Adhesive films were obtained by removing PET films from both sides of each adhesive sheet prepared in the examples and comparative examples. In the haze measurement, a haze meter (Nippon Denshoku Model NDH 5000) was used. The haze of the adhesive film was measured according to ASTM (American Association for Testing and Measurement) D 1003-955 ("Standard Test for Haze and Light Transmittance of Transparent Plastics").

[0172] (3) Storage modulus (unit: MPa): Using a dynamic viscoelastic meter ARES (MCR-501, Anton Paar), viscoelasticity was measured in automatic strain mode at a shear rate of 1 rad / sec and a strain of 1%. Specifically, multiple adhesive films obtained by removing all PET release films from each adhesive sheet prepared in the embodiments and comparative examples were stacked on each other to form a 500 μm thick laminate, which was then punched using an 8 mm diameter punch to prepare a sample. While the sample was heated from -60°C to 90°C at a heating rate of 5°C / min, the storage modulus of the sample was measured. In this article, the storage modulus at each temperature of -20°C, 25°C and 60°C was obtained.

[0173] (4) Peel strength to glass plate (unit: gf / 25 mm): Adhesive sheet samples (length × width: 100 mm × 25 mm) were prepared by cutting each of the adhesive sheets prepared in the examples and comparative examples. Using a corona treatment device, one surface of a PET film having a size of 150 mm × 25 mm × 75 μm (length × width × thickness) was subjected to corona treatment twice (total dose: 156) under 78 doses of plasma discharge. After removing the PET release film from one surface of each adhesive sheet sample, a glass plate (150 mm × 25 mm × 75 μm, length × width × thickness) was attached to the exposed surface of the adhesive film, and the remaining PET release film was removed from the other surface of the adhesive sheet sample, and then the corona-treated PET film was attached to the other surface of the adhesive film, thereby preparing a specimen for measuring peel strength, as shown in FIG. Figure 1 (a) shown.

[0174] The prepared specimen was autoclaved at 50° C. and 3.5 bar for 1,000 seconds, and fixed to a peel strength meter (TA.XT-Plus Texture Analyzer, Stable Micro System Co., Ltd.). Figure 1 (b) The T-peel strength (180 degree peel test) was measured by pulling the PET film from the glass plate at a speed of 50 mm / min at 25° C. by fixing the glass plate to a peel strength meter.

[0175] (5) Foldability: Module specimens were prepared by stacking a window film, an adhesive film, a polarizer, an adhesive film, and an OLED panel in sequence. In the preparation of the module, the window film, the adhesive film, the polarizer, the adhesive film, and the OLED panel are shown below, and the adhesive film is stacked on the polyimide film of the OLED panel.

[0176] - Window film: A PET film (thickness: 100 μm, Cosmoshine TA015, Toyobo Co., Ltd.) was used.

[0177] - Adhesive film: The adhesive films prepared in Examples and Comparative Examples were used.

[0178] -Polarizer: PVA resin dyed with iodine. A 80 μm thick polyvinyl alcohol film (degree of saponification: 99.5, degree of polymerization: 2,000) was immersed in a 0.3% iodine aqueous solution for dyeing, and stretched to an elongation of 5.0 in MD. Then, the stretched polyvinyl alcohol film was 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, thereby preparing a polarizer (thickness: 25 μm).

[0179] -OLED panel: A PET film (thickness: 100 μm, Cosmoshine TA015, Toyobo Co., Ltd.) was used.

[0180] Each prepared module sample was cut into a size of 170 mm × 110 mm (length × width), and then subjected to 100,000 folding cycles at -20°C to evaluate the generation of bubbles, cracks, and delamination of the module sample. When folding, the sample was folded in the longitudinal direction of the sample and in the direction of the OLED panel at a folding rate of 30 cycles per minute, so that the bent portion of the sample had a curvature radius of 1.5 mm, wherein 1 cycle refers to an operation of folding the adhesive film to have the curvature radius and then unfolding the adhesive film back to 180°. The absence of bubbles, cracks, and delamination generation was evaluated as good, and the generation of at least one type of bubbles, cracks, and delamination was evaluated as bad.

[0181] (6) Impact resistance (unit: cm): Reference Figure 2 Impact resistance was measured. The PET release film was removed from one surface of each adhesive sheet prepared in the examples and comparative examples, and a polyimide film (thickness: 50 μm, product name, manufacturer) was attached to the exposed surface of the adhesive sheet. Then, another PET release film was removed from the other surface of the adhesive sheet, and a polyethylene terephthalate film (thickness: 50 μm, product name, manufacturer) was attached to the other surface of the adhesive sheet, thereby preparing a sample in which the polyethylene terephthalate film 30, the adhesive film 20, and the polyimide film 10 were stacked in sequence, as shown in FIG. Figure 2 As shown in A in FIG. A pen 40 including a ball (ball) with a diameter of 0.7 mm and a circular cross section is used. Figure 2 The sample is dropped in the direction of the arrow (vertical direction) onto the upper surface of the polyimide film 10. Figure 2 As shown in B, the polyethylene terephthalate film 30 and the adhesive film 20 are removed from the sample, and the presence of the dent on the polyimide film 10 is observed by a 3D microscope (VK-X1100, Keyence Co., Ltd.). The initial dent formation height when the dent begins to form on the polyimide film is measured. The larger the initial dent formation height, the better the impact resistance. The impact resistance value of the adhesive film of Comparative Example 2 is set as a reference value, and the difference between the measured impact resistance value and the reference value is recorded. Δ1 means that the impact resistance value is 1 cm higher than the reference value, and 0 means that the impact resistance value is the same as the reference value. When evaluating impact resistance, Δ1 can be a value of 5 cm to 10 cm.

[0182] [Table 1]

[0183]

[0184]

[0185] * In Table 1, EHA: 2-ethylhexyl acrylate, HBA: 4-hydroxybutyl acrylate, EHDG: di(ethylene glycol) 2-ethylhexyl ether acrylate.

[0186] As shown in Table 1, the adhesive film according to the present invention has good foldability, low haze, good diffuse transmittance at near infrared wavelengths, and good impact resistance.

[0187] In contrast, the adhesive films of Comparative Examples could not provide all the effects of the present invention.

[0188] It should be understood that numerous modifications, changes, variations and equivalent embodiments may be made by those skilled in the art without departing from the spirit and scope of the present invention.

Claims

1. An adhesive film comprising inorganic particles having a refractive index of 1.5 or more, and having a diffuse transmittance of 3% or more at a near infrared wavelength, a haze of 5% or less, and a storage modulus of 0.2 MPa or less at -20°C.

2. The adhesive film according to claim 1, wherein The adhesive film has a peel strength of 500 gf / inch or more at 25°C.

3. The adhesive film according to claim 1, wherein The adhesive film has a storage modulus of 0.1 MPa or less at 25°C.

4. The adhesive film according to claim 1, wherein The adhesive film has a storage modulus of 0.1 MPa or less at 60°C.

5. The adhesive film according to claim 1, wherein The inorganic particles having a refractive index of 1.5 or more include zinc oxide.

6. The adhesive film according to claim 5, wherein The zinc oxide is present in an amount of 95 wt % or more in the inorganic particles having a refractive index of 1.5 or more.

7. The adhesive film according to claim 5, wherein The zinc oxide has an average particle size (D50) of 10 nm to 300 nm.

8. The adhesive film according to claim 5, wherein The zinc oxide includes a mixture of zinc oxides having different average particle sizes (D50).

9. The adhesive film according to claim 1, wherein The inorganic particles having a refractive index of 1.5 or more are present in the adhesive film in an amount of 0.01 wt % to 5 wt %.

10. The adhesive film according to claim 1, further comprising: Inorganic particles with a refractive index less than 1.

5.

11. The adhesive film according to claim 10, wherein The inorganic particles having a refractive index less than 1.5 include silicon dioxide.

12. The adhesive film according to claim 10, wherein The inorganic particles having a refractive index less than 1.5 are present in the adhesive film in an amount of 0.01 wt % to 20 wt %.

13. The adhesive film according to claim 10, wherein The adhesive film is formed of an adhesive film composition including the inorganic particles having a refractive index of 1.5 or more, the inorganic particles having a refractive index of less than 1.5, a polymer of a monomer mixture, and an initiator.

14. The adhesive film according to claim 13, wherein The polymer of the monomer mixture includes a polymer of a monomer mixture including an alkyl group-containing (meth)acrylic acid monomer and a hydroxyl group-containing (meth)acrylic acid monomer.

15. The adhesive film according to claim 13, wherein The polymer of the monomer mixture includes a polymer of a monomer mixture including an alkyl group-containing (meth)acrylic acid monomer, a hydroxyl group-containing (meth)acrylic acid monomer, and an alkylene glycol group-containing (meth)acrylic acid monomer.

16. The adhesive film according to claim 15, wherein The monomer mixture includes 10 to 75 wt % of the alkyl group-containing (meth)acrylic monomer, 2 to 40 wt % of the hydroxyl group-containing (meth)acrylic monomer, and 10 to 60 wt % of the alkylene glycol group-containing (meth)acrylic monomer.

17. The adhesive film according to claim 13, wherein The adhesive film composition further includes organic nanoparticles.

18. The adhesive film according to claim 17, wherein The organic nanoparticles include core-shell nanoparticles satisfying Relationship 1: [Equation 1] Tg(c) <Tg(s), Wherein, Tg(c) is the glass transition temperature of the core (unit: °C), and Tg(s) is the glass transition temperature of the shell (unit: °C). 19 . An optical member comprising the adhesive film according to claim 1 . 20 . An optical display device comprising the adhesive film according to claim 1 .

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