Adhesive film, optical component including same, and optical display device including same

Abstract

The present invention provides an adhesive film that contains inorganic particles with a refractive index of 1.5 or more, has a diffuse transmittance of 3% or more at near-infrared wavelengths, a haze of 5% or less, and a storage modulus of 0.2 MPa or less at -20°C, an optical component that includes the adhesive film, and an optical display device that includes the adhesive film.

Description

[Technical Field]

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

[0002] As interest in foldable optical display devices increases, there is a demand for adhesive films with excellent foldable properties. Adhesive films are used to adhere various optical elements to each other within optical display devices.

[0003] Currently, there is a high demand for mobile foldable display devices such as mobile phones. Mobile foldable display devices are structured so that users can write or draw using a pen. In this case, the adhesive film inside the display device needs to have a certain range of near-infrared diffuse transmittance so that users can clearly recognize the letters and pictures.

[0004] Technologies for optical sheets that ensure near-infrared diffuse transmittance have been developed. However, the development of adhesive films that can provide excellent foldability while ensuring near-infrared diffuse transmittance has not been completed. Meanwhile, since adhesive films may be located on the outer periphery of optical display devices, it is necessary for the adhesive film to have excellent impact resistance to prevent damage to the panel from external impacts.

[0005] The background art of the present invention is disclosed in Japanese Patent Application Laid-Open No. 2013-072951 and the like. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-072951 Summary of the Invention [Problem to be solved by the invention]

[0007] It is an object of the present invention to provide a self-adhesive film that offers excellent foldability, low haze, and excellent diffuse transmittance in the near infrared.

[0008] Another object of the present invention is to provide a pressure-sensitive adhesive film having excellent impact resistance. [Means for solving the problem]

[0009] One aspect of the present invention is a pressure-sensitive adhesive film.

[0010] 1. The adhesive film contains inorganic particles with a refractive index of 1.5 or more, has a diffuse transmittance of 3% or more at near-infrared wavelengths, a haze of 5% or less, and a storage modulus at -20°C of 0.2 MPa or less.

[0011] In 2.1, the adhesive film can have a peel strength of 500 gf / inch or more at 25°C.

[0012] In 3.1 to 2, the pressure-sensitive adhesive film may have a storage modulus at 25° C. of 0.1 MPa or less.

[0013] In 4.1 to 3, the pressure-sensitive adhesive film may have a storage modulus at 60°C of 0.1 MPa or less.

[0014] In 5.1 to 4, the inorganic particles having a refractive index of 1.5 or more may contain zinc-based oxide.

[0015] In 6.1 to 5, the zinc-based oxide may be contained in the inorganic particles having a refractive index of 1.5 or more at 95% by weight or more.

[0016] In 7.1 to 6, the zinc-based oxide may have an average particle size (D50) of 10 nm to 300 nm.

[0017] In 8.1 to 7, the zinc-based oxide may be a mixture of zinc-based oxides having different average particle sizes (D50).

[0018] In 9.1 to 8, the inorganic particles having a refractive index of 1.5 or more may be contained in the pressure-sensitive adhesive film in an amount of 0.01% by weight to 5% by weight.

[0019] In 10.1 to 9, the pressure-sensitive adhesive film may further contain inorganic particles having a refractive index of less than 1.5.

[0020] In 11.1 to 10, the inorganic particles having a refractive index of less than 1.5 may contain silica.

[0021] In 12.1 to 11, the inorganic particles having a refractive index of less than 1.5 may be contained in the pressure-sensitive adhesive film in an amount of 0.01% by weight to 20% by weight.

[0022] In 13.1 to 12, the adhesive film may be formed from a composition for adhesive films containing 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.

[0023] In 14.1 to 13, the polymer of the monomer mixture may be a polymer of a monomer mixture containing an alkyl group-containing (meth)acrylic monomer and a hydroxyl group-containing (meth)acrylic monomer.

[0024] In 15.1 to 14, the polymer of the monomer mixture may be a polymer of a monomer mixture containing an alkyl group-containing (meth)acrylic monomer, a hydroxyl group-containing (meth)acrylic monomer, and an alkylene glycol group-containing (meth)acrylic monomer.

[0025] In 16.1 to 15, the monomer mixture can contain 10% by weight to 75% by weight of the alkyl group-containing (meth)acrylic monomer, 2% by weight to 40% by weight of the hydroxyl group-containing (meth)acrylic monomer, and 10% by weight to 60% by weight of the alkylene glycol group-containing (meth)acrylic monomer.

[0026] In 17.1 to 16, the composition for a pressure-sensitive adhesive film may further contain organic nanoparticles.

[0027] In 18.1 to 17, the organic nanoparticles may include core-shell organic nanoparticles that satisfy the following mathematical formula 1: [Number 1] Tg(c) <Tg(s) (In the above formula 1, Tg(c) is the glass transition temperature (unit: ° C.) of the core, and Tg(s) is the glass transition temperature (unit: ° C.) of the shell.)

[0028] Another aspect of the present invention is an optical member.

[0029] The optical member includes the pressure-sensitive adhesive film of the present invention.

[0030] Yet another aspect of the present invention is an optical display device.

[0031] The optical display device comprises the adhesive film of the present invention. [Effects of the Invention]

[0032] The present invention can provide a pressure-sensitive adhesive film that offers excellent foldability, low haze, and excellent diffuse transmittance in the near infrared.

[0033] The present invention can provide a pressure-sensitive adhesive film having excellent impact resistance. [Brief explanation of the drawings]

[0034] [Figure 1] FIG. 2 is a schematic diagram showing the measurement of peel strength for an adhesive film according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing how impact resistance is measured for an adhesive film according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0035] The present application will be described in more detail below with reference to the following examples. However, the technology disclosed in the present application is not limited to the examples described herein and may be embodied in other forms. However, the examples introduced herein are provided for the purpose of ensuring consistency and completeness of the disclosed content and to fully convey the concept of the present application to those skilled in the art.

[0036] The terms used herein are merely used to describe exemplary embodiments and are not intended to limit the present invention. The singular expressions include the plural expressions unless the context clearly dictates otherwise.

[0037] The present invention may, however, be embodied in various different forms and should not be construed as limited to the embodiments set forth herein.

[0038] As used herein, "(meth)acrylic" can mean acrylic and / or methacrylic.

[0039] As used herein, a "copolymer" can include a polymer or a resin.

[0040] In this specification, the "refractive index" of inorganic particles is a value measured in the visible light region, specifically at a wavelength of 633 nm. For example, the refractive index of inorganic particles can be measured by a conventional method known to those skilled in the art, referring to a commercially available product catalog.

[0041] In this specification, "near-infrared wavelength" means a wavelength of 780 nm to 1400 nm.

[0042] In this specification, "diffractive transmittance" can be calculated in accordance with ASTM D 1003. For example, the diffuse transmittance is calculated by calculating the total light transmittance (TT) in a state where no adhesive film is used and the sheet is filled with air. I)) and diffuse transmittance (DT I ) and measure the total light transmittance (TT II ) and diffuse transmittance (DT II ) was measured, and the diffuse transmittance of the adhesive film was calculated according to the following formula.

[0043] <number> Diffuse transmittance of adhesive film = DT II -(TT II -((DT I ) / (TT I ))) In this specification, "haze" refers to the haze measured in the visible light region, for example, at wavelengths of 380 nm to 780 nm.

[0044] In this specification, the "average particle size" of organic nanoparticles refers to the particle size of organic nanoparticles expressed as a Z-average value measured in an aqueous or organic solvent using a Malvern Zetasizer nano-ZS device, and the particle size confirmed by SEM / TEM observation.

[0045] As used herein, the term "glass transition temperature of a homopolymer" refers to the glass transition temperature (Tg) of a homopolymer of a target monomer measured using a DSC Discovery from TA Instruments. Specifically, the homopolymer of a target monomer is heated to 180°C at a rate of 20°C / min, gradually cooled to -100°C, and then heated to 100°C at a rate of 10°C / min to obtain data as an endothermic transition curve, and the inflection point of the endothermic transition curve can be determined as the glass transition temperature.

[0046] In this specification, when describing a numerical range, "X to Y" means "X≦and≦Y".

[0047] The present invention relates to a pressure-sensitive adhesive film that satisfies diffuse transmittance and low haze in a specific range of near-infrared wavelengths, while also having excellent foldability. The present invention also relates to a pressure-sensitive adhesive film that has excellent impact resistance.

[0048] An adhesive film according to one embodiment of the present invention will be described below.

[0049] The adhesive film according to this example (hereinafter referred to as "adhesive film") has a diffuse transmittance at near-infrared wavelengths of 3% or more, a haze of 5% or less, and a storage modulus at -20°C of 0.2 MPa or less.

[0050] The adhesive film has a diffuse transmittance of 3% or more at near-infrared wavelengths. Within this range, when the adhesive film is attached to a mobile display such as a mobile phone and used, it can be smoothly driven when writing or drawing with a pen or the like. Specifically, the adhesive film has a diffuse transmittance of 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 ,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90%, specifically, it can be 3% over but less than 90%, more specifically, 3.2% to 10%.

[0051] The adhesive film has a haze of 5% or less. Within this range, the adhesive film may not affect image display when applied to an optical display device. Specifically, the adhesive film can have a haze of 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, 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, 5%, specifically 0% to 5%, more specifically 0.1% to 3%.

[0052] The PSA film has a storage modulus of 0.2 MPa or less at -20°C. Within this range, the PSA film can provide excellent foldability at low, normal, and high temperatures. Specifically, the PSA film has a storage modulus at -20°C of 0.001, 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2 MPa, 0.001 MPa to 0.2 MPa, more specifically, 0.1 MPa to 0.2 MPa.

[0053] The PSA film is formed from the PSA film composition described below to achieve the storage modulus at -20°C of the present invention and provide a diffuse transmittance of 3% or more at near-infrared wavelengths and a haze of 5% or less. In one embodiment, the PSA film may include a cured product of the composition. The PSA film composition of the present invention will be described in detail below.

[0054] The composition for adhesive films contains inorganic particles having a refractive index of 1.5 or more.

[0055] Inorganic particles with a refractive index of 1.5 or more can easily make the diffuse transmittance of the adhesive film at near-infrared wavelengths reach 3% or more.

[0056] In one specific example, the inorganic particles may have a refractive index of 1.5 to 2.5, for example, 1.8 to 2.3, or 2.0 to 2.5, or 1.9 to 2.2. Within this range, the PSA film can easily achieve a diffuse transmittance of 3% or more at near-infrared wavelengths and a haze of 5% or less. This is due to the difference in refractive index between the PSA film matrix and the PSA film matrix formed by curing the remaining components in the PSA film composition described below, excluding the inorganic particles with a refractive index of 1.5 or more.

[0057] The inorganic particles having a refractive index of 1.5 or higher are impregnated into a matrix for an adhesive film, and the difference in refractive index between the inorganic particles having a refractive index of 1.5 or higher and the matrix for an adhesive film can be 0.4 to 1.1, for example, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, or 1.1, for example, 0.6 to 1.0. Within this range, the diffuse transmittance and haze range of the adhesive film at near-infrared wavelengths can be easily achieved. The "matrix for an adhesive film" is a cured product formed by curing the remaining components of a composition for an adhesive film, excluding the inorganic particles having a refractive index of 1.5 or higher and the inorganic particles having a refractive index of less than 1.5 described below.

[0058] The present invention includes zinc-based oxide as inorganic particles having a refractive index of 1.5 or more. When zinc-based oxide is included in a matrix for an adhesive film that realizes a storage modulus at -20°C, as described below, it does not affect the storage modulus at -20°C, and it is particularly easy to achieve a diffuse transmittance of 3% or more and a haze of 5% or less at near-infrared wavelengths.

[0059] The zinc-based oxide may be zinc oxide alone or an aggregate containing zinc oxide and trace amounts of impurities.

[0060] The zinc-based oxide may be contained in the inorganic particles having a refractive index of 1.5 or more in an amount of 95 wt % or more, for example, 95 wt % to 100 wt %, for example, 100 wt %, in the inorganic particles having a refractive index of 1.5 or more. Within this range, the above-described effects of the present invention can be effectively realized.

[0061] Inorganic particles with a refractive index of 1.5 or higher can be spherical, amorphous, etc., and have an average particle size (D50) of 10 nm to 300 nm, specifically 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300 nm, or 30 nm to 200 nm. This range can reduce the problems of increased haze and poor folding properties of PSA films. In this specification, "average particle size (D50)" can be measured using conventional methods known to those skilled in the art. For example, the average particle size (D50) refers to the particle size corresponding to 50% of the particle size of inorganic particles as determined by weight cumulative analysis using a particle size analyzer.

[0062] In one specific example, the inorganic particles having a refractive index of 1.5 or more may be solely inorganic particles having an average particle size (D50) of 10 nm to 300 nm, specifically 120 nm to 200 nm.

[0063] In another specific example, the inorganic particles having a refractive index of 1.5 or more may be a mixture of two or more inorganic particles having different average particle sizes (D50). For example, the inorganic particles having a refractive index of 1.5 or more may be a mixture of first inorganic particles having an average particle size (D50) of 10 nm to 300 nm, specifically 30 nm to 200 nm, more specifically 120 nm to 200 nm; and second inorganic particles having an average particle size (D50) of 10 nm to 300 nm, specifically 10 nm or more but less than 100 nm. The weight ratio of the first inorganic particles to the second inorganic particles in the inorganic particles having a refractive index of 1.5 or more can be 1:0.1 to 1:3, for example, 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, 1:0.5 to 1:2.

[0064] 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 PSA film composition. The surface treatment method for inorganic particles having a refractive index of 1.5 or more can be carried out by a conventional method known to those skilled in the art.

[0065] The inorganic particles with a refractive index of 1.5 or higher can be contained in the PSA film at 0.01 to 5 wt%, 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, 2, 3, 4, or 5 wt%, specifically 0.05 to 2 wt%. Within this range, the PSA film can easily achieve the diffuse transmittance, haze, and storage modulus at -20°C in the near-infrared wavelength range.

[0066] The inorganic particles with a refractive index of 1.5 or higher can be included in an amount of 0.01 to 2 parts by weight, for example, 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, 2 parts by weight, or 0.05 to 0.5 parts by weight, per 100 parts by weight of the monomer mixture described below. Within this range, the PSA film can easily achieve the diffuse transmittance at near-infrared wavelengths, haze, and storage modulus at -20°C.

[0067] The composition for a pressure-sensitive adhesive film further contains a polymer of the monomer mixture and an initiator.

[0068] A composition containing a polymer of a monomer mixture and an initiator can be cured to form a matrix of an adhesive film. The polymer can be a mixture of a partial polymer of the monomer mixture and an unreacted monomer, or the polymer can be a copolymer of the monomer mixture.

[0069] The monomer mixture may contain a (meth)acrylic monomer having an alkyl group and a (meth)acrylic monomer having a hydroxyl group.

[0070] The alkyl group-containing (meth)acrylic monomer can easily form the matrix of the PSA film. In one specific example, the alkyl group-containing (meth)acrylic monomer can be a linear or branched (meth)acrylate containing an alkyl group having 1 to 10 carbon atoms and unsubstituted at the ester moiety. For example, the alkyl group-containing (meth)acrylic monomer can include one or more of 2-ethylhexyl (meth)acrylate, n-butyl (meth)acrylate, isooctyl (meth)acrylate, propyl (meth)acrylate, t-butyl (meth)acrylate, iso-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, and decyl (meth)acrylate, preferably one or more of 2-ethylhexyl (meth)acrylate, n-butyl (meth)acrylate, and isooctyl (meth)acrylate, and more preferably 2-ethylhexyl (meth)acrylate.

[0071] The glass transition temperature of the homopolymer of the alkyl group-containing (meth)acrylic monomer may be −80° C. to −20° C., specifically −80° C. to −40° C. Within this range, the foldability of the pressure-sensitive adhesive film at low temperatures and at high temperatures and humidity may be improved.

[0072] The alkyl group-containing (meth)acrylic monomer may be contained in the monomer mixture in an amount of 10 to 75% by weight, preferably 10 to 70% by weight, or 15 to 60% by weight. Within this range, the bending reliability of the PSA film at low temperatures and high temperatures and humidity may be improved.

[0073] The hydroxyl group-containing (meth)acrylic monomer can facilitate the provision of peel strength to the PSA film. The hydroxyl group-containing (meth)acrylic monomer can be a C1 to C10 (meth)acrylate containing one or more hydroxyl groups in the ester moiety. For example, the hydroxyl group-containing (meth)acrylic monomer can include one or more 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.

[0074] The hydroxyl group-containing (meth)acrylic monomer may have a homopolymer glass transition temperature of −70° C. to 0° C., preferably −60° C. to −10° C., and more preferably −50° C. to −20° C. Within this range, the peel strength and foldability of the pressure-sensitive adhesive film can be improved.

[0075] The hydroxyl group-containing (meth)acrylic monomer may be contained in the monomer mixture in an amount of 2 to 40% by weight, for example, 10 to 30% by weight, 2 to 20% by weight, or 5 to 20% by weight. Within this range, the adhesive strength and durability reliability of the PSA film may be further improved.

[0076] The monomer mixture may further contain an alkylene glycol group-containing (meth)acrylic monomer. By containing an alkylene glycol group, the alkylene glycol group-containing (meth)acrylic monomer can easily provide the PSA film with excellent foldability. In this specification, "alkylene glycol group" means (alkylene-O- having 2 to 4 carbon atoms).

[0077] The alkylene glycol group-containing (meth)acrylic monomer can have a homopolymer glass transition temperature of -90°C to -55°C, preferably -90°C to -60°C, and more preferably -75°C to -60°C. Within this range, the modulus of the pressure-sensitive adhesive film at low temperatures can be reduced, and the pressure-sensitive adhesive film's foldability at low temperatures can be improved. The alkylene glycol group-containing (meth)acrylate can include a monofunctional acrylate having an ethylene oxide group (-CH2CHO-) or a propylene oxide group (-CH2CH2CHO-), preferably an ethylene oxide group.

[0078] The (meth)acrylic monomer having an alkylene glycol group may be, for example, an ether-based (meth)acrylate containing 1 mole or more, for example, 2 to 20 moles, of ethylene glycol. Specifically, the ethylene glycol group-containing (meth)acrylate may include one or more of poly(ethylene glycol) methyl ether (meth)acrylate containing 6 to 13 moles of ethylene glycol, poly(ethylene glycol) ethylhexyl ether (meth)acrylate containing 2 to 10 moles of ethylene glycol, and poly(ethylene glycol) octyl ether (meth)acrylate containing 2 to 20 moles of ethylene glycol. Preferably, the alkylene glycol group-containing (meth)acrylate may include one or more of di(ethylene glycol) 2-ethylhexyl ether (meth)acrylate, triethylene glycol 2-ethylhexyl ether (meth)acrylate, and di(ethylene glycol) octyl ether (meth)acrylate.

[0079] The alkylene glycol group-containing (meth)acrylic monomer may be contained in the monomer mixture in an amount of 10 to 60% by weight, preferably 20 to 60% by weight, and more preferably 20 to 50% by weight. Within this range, the PSA film can be improved in repeated folding properties at low temperatures.

[0080] In one embodiment, the total amount of the alkyl group-containing (meth)acrylic monomer, the hydroxyl group-containing (meth)acrylic monomer, and the alkylene glycol group-containing (meth)acrylic monomer in the monomer mixture may be 98% by weight or more, for example, 98% by weight to 100% by weight, for example, 100% by weight. Within this range, the effects of the present invention may be easily realized.

[0081] 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 additional effects to the PSA film.

[0082] The comonomer is a monomer different from the above-mentioned monomers, and can include one or more of a monomer having an amine group, a monomer having an alkoxy group, a monomer having a phosphoric acid group, a monomer having a sulfonic acid group, a monomer having a phenyl group, a monomer having a silane group, a monomer having a carboxylic acid group, and an amide group-containing monomer.

[0083] The monomer having an amine group may be an amine group-containing acrylic monomer such as monomethylaminoethyl acrylate, monoethylaminoethyl acrylate, monomethylaminopropyl acrylate, monoethylaminopropyl acrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, N-tert-butylaminoethyl acrylate, acryloxyethyltrimethylammonium chloride acrylate, etc., but is not limited thereto.

[0084] The monomer having an alkoxy group may be, but is not limited to, 2-methoxyethyl acrylate, 2-methoxypropyl acrylate, 2-ethoxypropyl acrylate, 2-butoxypropyl acrylate, 2-methoxypentyl acrylate, 2-ethoxypentyl acrylate, 2-butoxyhexyl acrylate, 3-methoxypentyl acrylate, 3-ethoxypentyl acrylate, or 3-butoxyhexyl acrylate.

[0085] The monomer having a phosphate group may be an acrylic monomer having a phosphate group, such as 2-methacryloyloxyethyl diphenyl phosphate acrylate, trimethacryloyloxyethyl phosphate acrylate, or triacryloyloxyethyl phosphate acrylate, but is not limited thereto.

[0086] The monomer having a sulfonic acid group may be an acrylic monomer having a sulfonic acid group, such as sodium sulfopropyl acrylate, sodium 2-sulfoethyl acrylate, or sodium 2-acrylamido-2-methylpropanesulfonate, but is not limited thereto.

[0087] The monomer having a phenyl group may be an acrylic vinyl monomer having a phenyl group, such as p-tert-butylphenyl acrylate, o-biphenyl acrylate, or phenoxyethyl acrylate, but is not limited thereto.

[0088] The monomer having a silane group can be a vinyl monomer having a silane group, such as 2-acetoacetoxyethyl acrylate, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethyl)silane, vinyltriacetoxysilane, acryloyloxypropyltrimethoxysilane, etc., but is not limited thereto.

[0089] The monomer having a carboxylic acid group can be, but is not limited to, acrylic acid, 2-carboxyethyl acrylate, 3-carboxypropyl acrylate, 4-carboxybutyl acrylate, itaconic acid, crotonic acid, maleic acid, fumaric acid, and maleic anhydride.

[0090] The amide group-containing monomer may be, but is not limited to, acrylamide, N-methylacrylamide, N-methylolacrylamide, N-methoxymethylacrylamide, N,N-methylenebisacrylamide, N-hydroxyethylacrylamide, N,N-diethylacrylamide, etc.

[0091] The comonomer may be contained in the monomer mixture in an amount of 30% by weight or less, preferably 0% to 30% by weight, and may be used to adjust the adhesive strength with the adherend and to impart optical properties.

[0092] The initiator may cure the composition for a pressure-sensitive adhesive film to form a pressure-sensitive adhesive film, or may polymerize the monomer mixture in the composition for a pressure-sensitive adhesive film to polymerize the remaining monomers. The initiator may include a photoinitiator, preferably a photoradical initiator.

[0093] Any photoinitiator can be used as long as it can induce a polymerization reaction of the radical polymerizable compound described below during the curing process by irradiation with light or the like. For example, benzoin-based, hydroxyketone-based, aminoketone-based, or phosphine oxide-based photoinitiators can be used. Specifically, acetophenone compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, 2,2-dimethoxy-2-phenylacetophenone, 2,2'-diethoxyacetophenone, 2,2'-dibutoxyacetophenone, 2-hydroxy-2-methylpropiophenone, pt-butyltrichloroacetophenone, pt-butyldichloroacetophenone, 4-chloroacetophenone, and 2,2'-dichloro-4-phenoxyacetophenone, dimethylaminoanilineacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone, and the like can be used. Tan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4 bisdiethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, 2-aminoanthraquinone, Examples of suitable thioxanthone include 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoic acid ester, oligo[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone], and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide.

[0094] The initiator may be included 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 curing reaction can be completed, the remaining initiator can be prevented from reducing the light transmittance of the PSA film, and the generation of bubbles can be reduced, resulting in excellent reactivity.

[0095] The composition for a PSA film may further contain inorganic particles having a refractive index of less than 1.5.

[0096] In one specific example, inorganic particles with a refractive index of less than 1.5 can enhance the impact resistance of the PSA film rather than increasing the diffuse transmittance of the PSA film at near-infrared wavelengths. In one specific example, the PSA film may have an initial dent height of 5 cm or more, for example, 5 cm to 10 cm, as a result of the impact resistance evaluation described below. Within this range, even when the PSA film is laminated on a light-emitting element-containing panel, damage to the panel due to external impact can be prevented. In this specification, "impact resistance" can be measured by the method described below.

[0097] Inorganic particles with a refractive index of less than 1.5 may have a refractive index of 1.3 or more but less than 1.5, such as 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 diffuse transmittance and haze of the PSA film at near-infrared wavelengths may not be affected.

[0098] In one embodiment, the inorganic particles having a refractive index of less than 1.5 may be silica. For example, the silica may be solid silica, hollow silica, core-shell silica, etc.

[0099] The inorganic particles having a refractive index of less than 1.5 may be spherical or amorphous, and may have a smaller average particle size (D50) than the inorganic particles having a refractive index of 1.5 or more. This prevents the PSA film from affecting the diffuse transmittance at near-infrared wavelengths, while also improving impact resistance.

[0100] Alternatively, inorganic particles having a refractive index of less than 1.5 may be contained in an excessive amount in the PSA film compared to inorganic particles having a refractive index of 1.5 or more. For example, inorganic particles having a refractive index of less than 1.5 may be contained in the PSA film in an amount 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, 30 times, or 20 to 30 times the amount of inorganic particles having a refractive index of 1.5 or more, based on parts by weight.

[0101] Specifically, inorganic particles with a refractive index of less than 1.5 have an average particle size (D50) of 1 nm to 50 nm, for example, 1, 2, 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 nm, or 5 nm to 30 nm. Within this range, the effects of adding inorganic particles with a refractive index of less than 1.5 can be obtained.

[0102] The inorganic particles having a refractive index of less than 1.5 can be contained in the PSA film at 0.01 to 20% by weight, for example, 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20% by weight, 1 to 10% by weight, 1 to 5% by weight, or 2 to 8% by weight. Within this range, the impact resistance of the PSA film can be improved, and the effects of the present invention can be achieved.

[0103] The inorganic particles having a refractive index of less than 1.5 may be included in an amount of 0.1 to 10 parts by weight, for example, 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 parts by weight, or 1 to 5 parts by weight, relative to 100 parts by weight of the monomer mixture. Within this range, the impact resistance of the PSA film may be improved, and the effects of the present invention may be exhibited.

[0104] The composition for a pressure-sensitive adhesive film may further include organic nanoparticles.

[0105] The organic nanoparticles increase the storage modulus of the adhesive film at high temperatures, eliminating peeling, lifting, and / or the generation of bubbles in the adhesive film at high temperatures, thereby improving reliability at high temperatures. The organic nanoparticles have a high glass transition temperature and can increase the modulus of the adhesive film at high temperatures.

[0106] The organic nanoparticles may have an average particle size of 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 range, the adhesive film may have good transparency because the total light transmittance in the visible light region is 90% or more without affecting the folding of the adhesive film.

[0107] The difference in refractive index between the organic nanoparticles and the polymer of the monomer mixture containing the (meth)acrylic monomer may be 0.1 or less, specifically 0 to 0.05, more specifically 0 to 0.02. Within this range, the transparency of the PSA film may be excellent.

[0108] In one embodiment, the organic nanoparticles may have a refractive index of 1.35 to 1.70, specifically 1.40 to 1.60. Within this range, the transparency of the adhesive film may be excellent.

[0109] Organic nanoparticles may include, but are not limited to, simple nanoparticles such as core-shell nanoparticles and bead nanoparticles. In the case of core-shell nanoparticles, the core and shell may satisfy the following formula 1: In other words, the core and shell may both be organic nanoparticles. When the particle has such a particle shape, the adhesive film can be easily folded and exhibits a balanced physical property of elasticity and flexibility. [Number 1] Tg(c) <Tg(s) (In the above formula 1, Tg(c) is the glass transition temperature (unit: ° C.) of the core, and Tg(s) is the glass transition temperature (unit: ° C.) of the shell.)

[0110] As used herein, "shell" refers to the outermost layer of an organic nanoparticle. The core can be a single spherical particle. However, the core can also include an additional layer surrounding the spherical particle, as long as it has the above-mentioned glass transition temperature.

[0111] Specifically, the glass transition temperature of the core may be -150°C to 10°C, more specifically -150°C to -5°C, and more specifically -150°C to -20°C. Within this range, the PSA film can exhibit low-temperature and / or room-temperature viscoelasticity. The core may contain one or more of polyalkyl acrylate, polysiloxane, or polybutadiene having the above glass transition temperature.

[0112] The polyalkyl acrylate may include, but is not necessarily limited to, one or more of polymethyl acrylate, polyethyl acrylate, polypropyl acrylate, polybutyl acrylate, polyisopropyl acrylate, polyhexyl acrylate, polyhexyl methacrylate, polyethylhexyl acrylate, and polyethylhexyl methacrylate, polysiloxane.

[0113] The polysiloxane can be, for example, an organosiloxane (co)polymer. The organosiloxane (co)polymer may be either uncrosslinked or crosslinked. A crosslinked organosiloxane (co)polymer can be used for impact resistance and colorability. This is a crosslinked organosiloxane, specifically, crosslinked dimethylsiloxane, methylphenylsiloxane, diphenylsiloxane, or a mixture of two or more thereof. By using a copolymer of two or more organosiloxanes, the refractive index can be adjusted to 1.41 to 1.50.

[0114] The crosslinking state of an organosiloxane (co)polymer can be determined by the degree of solubility in various organic solvents. The more crosslinked the polymer, the less soluble it is in the solvent. Acetone, toluene, etc. can be used as a solvent for determining the crosslinking state. Specifically, the organosiloxane (co)polymer may have a portion that is insoluble in acetone or toluene. The toluene-insoluble portion of the organosiloxane copolymer may be 30% or more.

[0115] Furthermore, the organosiloxane (co)polymer may further include an alkyl acrylate crosslinked polymer. The alkyl acrylate crosslinked polymer may be methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, etc. For example, n-butyl acrylate or 2-ethylhexyl acrylate, which have a low glass transition temperature, may be used.

[0116] Specifically, the glass transition temperature of the shell may be 15°C to 150°C, more specifically 35°C to 150°C, and more specifically 50°C to 140°C. Within this range, the dispersibility of the organic nanoparticles in the acrylic copolymer may be excellent. The shell may include a polyalkyl methacrylate having the above glass transition temperature. For example, the shell may include one or more of polymethyl methacrylate (PMMA), polyethyl methacrylate, polypropyl methacrylate, polybutyl methacrylate, polyisopropyl methacrylate, polyisobutyl methacrylate, and polycyclohexyl methacrylate, but is not necessarily limited thereto.

[0117] The core may be contained in the organic nanoparticles at 30% to 99% by weight, specifically 40% to 95% by weight, and more specifically 50% to 90% by weight. This range may improve the foldability of the adhesive film over a wide temperature range. The shell may be contained in the organic nanoparticles at 1% to 70% by weight, specifically 5% to 60% by weight, and more specifically 10% to 50% by weight. This range may improve the foldability of the adhesive film over a wide temperature range.

[0118] The organic nanoparticles may be contained in the adhesive film in an amount of 0 to 20% by weight, specifically 0.1 to 20% by weight, specifically 0.5 to 12% by weight, specifically 0.5 to 8% by weight. Within this range, the modulus of the adhesive film at high temperatures may be increased, and the foldability of the adhesive film at room temperature and high temperatures may be improved, resulting in excellent viscoelasticity of the adhesive film at low and / or room temperatures.

[0119] The organic nanoparticles may be contained in an amount of 0 to 10 parts by weight, 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 can exhibit excellent foldability at high temperatures.

[0120] The organic nanoparticles can be produced by a conventional emulsion polymerization, suspension polymerization, or solution polymerization method.

[0121] The composition for a pressure-sensitive adhesive film may further contain a crosslinking agent.

[0122] The crosslinking agent can increase the degree of crosslinking of the pressure-sensitive adhesive composition and increase the mechanical strength of the pressure-sensitive adhesive film.

[0123] The crosslinking agent can include a multifunctional (meth)acrylate that can be cured with actinic radiation. For example, the crosslinking agent can be 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, dicyclopentanyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified di(meth)acrylate, di(meth)acryloxyethyl isocyanurate, allylated cyclopentanol di(meth)acrylate, di ... dicyclohexyl di(meth)acrylate, tricyclodecane dimethanol (meth)acrylate, dimethylol dicyclopentane di(meth)acrylate, ethylene oxide-modified hexahydrophthalic acid di(meth)acrylate, tricyclodecane dimethanol (meth)acrylate, neopentyl glycol-modified trimethylpropane di(meth)acrylate, adamantane di(meth)acrylate, or 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene, etc. Difunctional acrylates; 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, or tris(meth)acryloxyethyl isocyanurate; diglycerin tetra(meth)acrylate, or pentaerythritol tri(meth)acrylate; Examples of the acrylate include, but are not limited to, tetrafunctional acrylates such as dipentaerythritol tetra(meth)acrylate; pentafunctional acrylates such as dipentaerythritol penta(meth)acrylate; and hexafunctional acrylates such as dipentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, or urethane(meth)acrylate (e.g., a reaction product of an isocyanate monomer and trimethylolpropane tri(meth)acrylate).

[0124] The crosslinking agent may be included 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, based on 100 parts by weight of the monomer mixture or the polymer of the monomer mixture, which has the effect of providing excellent peel strength and increasing reliability.

[0125] The PSA film composition may further include additives. The additives are contained in the PSA film composition and may include common additives known to those skilled in the art. For example, the additives may include one or more of a pigment, an ultraviolet absorber, a leveling agent, and an antistatic agent, but are not limited thereto.

[0126] The PSA film may have a peel strength of 500 gf / inch or more, for example, 500 gf / inch to 3000 gf / inch, at 25°C. Within this range, the PSA film can easily provide excellent foldability. In this specification, "peeling strength" refers to T-peel peel strength. The T-peel peel strength can be measured by the method described in the following experimental examples, and the adherend may be a glass plate, for example, an alkali-free glass plate.

[0127] 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 excellent 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.

[0128] The adhesive film may have a haze of 2% or less, specifically 0.1% to 1%, and a total light transmittance of 90% or more, specifically 95% to 99%, in the visible light region (e.g., wavelength 380 nm to 780 nm).Within these ranges, the optical transparency is improved and the film can be used in optical display devices.

[0129] The adhesive film may have a thickness of 10 μm to 300 μm, specifically 20 μm to 100 μm. With a thickness in this range, it can be used in optical display devices.

[0130] The PSA film composition can be prepared by partially polymerizing the monomer mixture as an initiator and adding an additional initiator. The aforementioned organic nanoparticles, crosslinking agents, additives, etc. may also be added. The partial polymerization can include solution polymerization, suspension polymerization, photopolymerization, bulk polymerization, or emulsion polymerization. Specifically, solution polymerization can be carried out at 50°C to 100°C by adding an initiator to the monomer mixture. Examples of initiators that can be used include acetophenone-based initiators, such as 2,2-dimethoxy-2-phenylacetophenone, and photopolymerization initiators, such as 1-hydroxycyclohexyl phenyl ketone. The partial polymerization can have a viscosity of 300 cPs to 50,000 cPs at 25°C, specifically 500 cPs to 9,000 cPs.

[0131] The pressure-sensitive adhesive film is a reduced-pressure pressure-sensitive adhesive film and can be produced by a conventional method. For example, it can be produced by coating a release film with a composition for pressure-sensitive adhesive films and then curing it. The curing is photo-curing using a low-pressure lamp in an oxygen-free environment at a wavelength of 300 nm to 400 nm and an irradiation dose of 400 mJ / cm. 2 ~3000mJ / cm 2 The irradiation may include

[0132] An optical member according to an embodiment of the present invention includes an optical film and an adhesive film formed on at least one surface of the optical film, and the adhesive film may include an adhesive film according to an embodiment of the present invention. Therefore, the optical member has good bending and / or folding properties and can be used in flexible display devices.

[0133] In one embodiment, the optical film provides a certain optical function in a display device, such as polarization, optical compensation, improvement of display quality, and / or conductivity. Examples of the optical film include window films, windows, polarizers, color filters, retardation films, elliptical polarizing films, reflective polarizing films, anti-reflection films, compensation films, brightness enhancement films, alignment films, light diffusing films, glass shatterproof films, surface protection films, OLED device barrier layers, plastic LCD substrates, transparent electrode films including indium tin oxide (ITO), fluorinated tin oxide (FTO), aluminum doped zinc oxide (AZO), carbon nanotubes (CNTs), Ag nanowires, graphene, etc. Methods for manufacturing the optical film can be easily achieved by those skilled in the art.

[0134] For example, a touch panel can be formed by attaching a touchpad to a window or optical film using an adhesive film, or it can be applied to a conventional polarizing film as an adhesive film.

[0135] In another embodiment, the optical film is an optically transparent optical film, and the optical member including the optical film and the adhesive film can function as a support layer for a display element. For example, the display element can include a window film, etc. The window film can include the optical element and a window coating layer (e.g., a silicone-based coating layer) formed on the optical element. Specifically, the optical film can have a total light transmittance of 90% or more in the visible light range and can be a film formed from one or more resins, such as cellulose resins including triacetyl cellulose, polyester resins including polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, etc., polycarbonate resins, polyimide resins, polystyrene resins, polyacrylate resins including polymethyl methacrylate, etc., cyclic olefin polymer resins, acrylic resins, and polyamide resins. The optical film can 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, it can be used as a support layer for a display element.

[0136] The optical display device of the present invention may include the pressure-sensitive adhesive film of the present invention. The optical display device may include an organic light-emitting device display device, a liquid crystal display device, etc. The optical display device may include a flexible display device. However, the optical display device may also include a non-flexible display device. [Example]

[0137] The present invention will be described in more detail with reference to the following examples, which are provided for illustrative purposes only and are not intended to limit the scope of the present invention.

[0138] Example 1 As shown in Table 1 below, 100 parts by weight of a monomer mixture was prepared, and 0.005 parts by weight of the photoinitiator Irgacure 651 was added and thoroughly mixed in a reactor. After replacing the dissolved oxygen in the reactor with nitrogen gas, the monomer mixture was partially polymerized by irradiating it with ultraviolet light using a low-pressure mercury lamp for several minutes, producing a composition containing a partially (meth)acrylic copolymer of the monomer mixture. As shown in Table 1 below, 0.3 parts by weight of the 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 to produce a composition for adhesive films.

[0139] The composition for adhesive films was applied to a PET (polyethylene terephthalate) film, which was a release film, and the resulting coating layer was covered with another PET film, which was also a release film, and the composition was exposed to ultraviolet light at 2000 mJ / cm 2 A pressure sensitive adhesive sheet of PET film-adhesive film-PET film was produced by irradiating the film with a light intensity of 1000 kJ / cm2.

[0140] Example 2 After partial polymerization in Example 1, an adhesive sheet was manufactured in the same manner as in Example 1, except that an adhesive film was manufactured by adding 0.3 parts by weight of 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 silica (SiO2, average particle size (D50) 15 nm, refractive index: 1.46).

[0141] Example 3 An adhesive sheet was manufactured in the same manner as in Example 2, except that in Example 2, 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 silica (SiO2, average particle size (D50) 15 nm, refractive index: 1.46) were added.

[0142] Example 4 Organic nanoparticles were prepared by emulsion polymerization. The core was made of polybutyl acrylate and the shell was made of polymethyl methacrylate. The shell was 35% by weight of the organic nanoparticles, and the core was 65% by weight of the organic nanoparticles. The average particle size (D50) was 100 nm, and the refractive index was 1.48.

[0143] An adhesive sheet was manufactured in the same manner as in Example 2, except that in Example 2, 0.2 parts by weight of zinc oxide (ZnO, average particle size (D50) 150 nm, refractive index: 2.0), 5 parts by weight of silica (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) were added.

[0144] Comparative Examples 1 and 2 An adhesive sheet was produced in the same manner as in Example 2, except that the composition of the adhesive film composition in Example 2 was changed as shown in Table 1 below.

[0145] Comparative Example 3 An adhesive sheet was manufactured 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 was changed as shown in Table 1 below.

[0146] Comparative Example 4 An adhesive sheet was manufactured 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 in Example 1 and the content was changed as shown in Table 1 below.

[0147] Comparative Example 5 Organic nanoparticles were prepared in the same manner as in Example 4.

[0148] An adhesive sheet was manufactured in the same manner as in Example 1, except that the organic nanoparticles (refractive index 1.48, average particle size (D50) 100 nm) prepared above were used instead of zinc oxide.

[0149] The structures of the adhesive films of the Examples and Comparative Examples are shown in Table 1 below. The adhesive sheets of the Examples and Comparative Examples were used to evaluate the physical properties shown in Table 1 below.

[0150] (1) Diffuse transmittance at near-infrared wavelengths (unit: %): The PET release films were all peeled off from the pressure-sensitive adhesive sheets of the Examples and Comparative Examples to obtain pressure-sensitive adhesive films. The diffuse transmittance at near-infrared wavelengths was measured for the pressure-sensitive adhesive films using a UV spectrometer and an integrating sphere in accordance with ASTM D 1003 according to the above formula.

[0151] (2) Haze (unit: %): The PET film was completely peeled off from the adhesive sheet to obtain an adhesive film, and the haze of the adhesive film was measured using a haze meter (Nippon Denshoku Model NDH5000) according to ASTM (American Society for Testing and Measurement) test method D 1003-95 5 ("Standard Test for Haze and Luminous Transmittance of Transparent Plastic").

[0152] (3) Storage modulus (unit: MPa): Viscoelasticity was measured under autostrain conditions at a shear rate of 1 rad / sec and strain of 1% using a dynamic viscoelasticity measuring device, ARES (Anton Paar MCR-501). After removing all PET release films from the adhesive sheet, adhesive film was laminated to a thickness of 500 μm, and the laminate was punched using an 8 mm diameter punch to prepare a specimen. The storage modulus was measured at a temperature increase rate of 5°C / min from -60°C to 90°C, and the storage modulus was calculated at -20°C, 25°C, and 60°C.

[0153] (4) Peel force from glass plate (unit: gf / 25 mm): The pressure-sensitive adhesive sheets of the examples and comparative examples were cut into a size (width x length, 100 mm x 25 mm). A PET (polyethylene terephthalate) film measuring 150 mm x 25 mm x 75 μm in width x length x thickness was subjected to corona treatment twice at a dose of 78 using a corona treatment machine (total dose: 156 doses). One of the PET films was released from the cut pressure-sensitive adhesive sheet, and a glass plate (width x length x thickness, 150 mm x 25 mm x 75 μm) was attached to the exposed pressure-sensitive adhesive film surface. The other PET release film in the pressure-sensitive adhesive sheet was then released, and the resulting corona-treated PET film (width x length x thickness, 150 mm x 25 mm x 75 μm) was then placed on top of the glass plate to prepare a specimen for peel force measurement, as shown in Figure 1(a).

[0154] The specimen was autoclaved at 3.5 bar pressure and 50°C for 1000 seconds and then fixed in a TA.XT_Plus Texture Analyzer (Stable Micro System). Referring to Figure 1(b), the TA.XT_Plus Texture Analyzer was fixed to a glass plate at 25°C, and the PET film was pulled at a speed of 50 mm / min to measure the T-Peel peel strength (180° peel test).

[0155] (5) Folding characteristics: A module specimen was fabricated by laminating a window film, adhesive film, polarizer, adhesive film, and OLED panel in this order. The following window film, adhesive film, polarizer, adhesive film, and OLED panel were used to fabricate the module, and the adhesive film was laminated on the polyimide film in the OLED panel: -Window film: Replaced with PET film (thickness: 100μm, Cosmoshine TA015, Toyobo).

[0156] -Adhesive film: Adhesive film (thickness: 15 μm) produced in the examples and comparative examples Polarizer: PVA resin dyed with iodine was used. An 80μm thick polyvinyl alcohol film (saponification degree: 99.5, polymerization degree: 2000) was immersed in a 0.3% iodine aqueous solution to dye it, and then stretched in the MD direction to a stretch ratio of 5.0. The stretched polyvinyl alcohol film was then immersed in a 3% boric acid solution and a 2% potassium iodide aqueous solution to correct the color, and then dried at 50°C for 4 minutes to produce a polarizer (25μm thick).

[0157] -OLED panel: Replaced with polyimide film (thickness: 100 μm, Cosmoshine TA015, Toyobo).

[0158] The manufactured module specimens were cut into a length x width of 170mm x 110mm and folded 100,000 times at -20°C to evaluate whether bubbles, cracks, or delamination occurred in the module specimens. The module specimens were folded in the length direction and in the direction of the OLED panel, with a bending radius of 1.5mm, at 30 cycles per minute, where one cycle meant folding the specimen at that bending radius and then unfolding it 180°. A satisfactory result was determined if no bubbles, cracks, or delamination occurred, and a satisfactory result was determined if one or more of the following occurred: bubbles, cracks, or delamination.

[0159] (6) Impact Resistance (unit: cm): Impact resistance was measured with reference to Figure 2. One PET film was peeled from each of the pressure-sensitive adhesive sheets prepared in the Examples and Comparative Examples, and a polyimide film (thickness: 50 μm, product name, manufacturer) was attached to the peeled surface. The remaining release PET film was peeled from each of the pressure-sensitive adhesive sheets, and a polyethylene terephthalate film (thickness: 100 μm, product name, manufacturer) was attached to the peeled surface to produce the specimen shown in Figure 2A, in which a polyethylene terephthalate film 30, an adhesive film 20, and a polyimide film 10 were laminated in that order. A pen 40 with a diameter of 0.7 mm and a circular cross section was dropped on the top surface of the polyimide film 10 in the direction of the arrow (vertical direction) in Figure 2. As shown in Figure 2B, the polyethylene terephthalate film 30 and adhesive film 20 were removed, and the formation of a dent in the polyimide film 10 was confirmed using a 3D microscope (VK-X1100, Keyence Corporation). The initial height at which a dent began to appear was measured. A higher initial height indicates better impact resistance. The impact resistance value measured in Comparative Example 2 was taken as the reference value, and the difference between the measured impact resistance value and the reference value was recorded. △1 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. △1 can be 5 cm to 10 cm when evaluating impact resistance.

[0160] [Table 1]

[0161] *In Table 1 above, EHA: 2-ethylhexyl acrylate, HBA: 4-hydroxybutyl acrylate, EHDG: di(ethylene glycol) 2-ethylhexyl ether acrylate As shown in Table 1, the pressure-sensitive adhesive film of the present invention provided excellent foldability, low haze, and excellent diffuse transmittance in the near infrared, and was excellent in impact resistance.

[0162] On the other hand, the adhesive films of the comparative examples were unable to provide all of the effects of the present invention.

[0163] Simple variations or modifications of the present invention can be easily implemented by those skilled in the art, and all such variations and modifications can be considered to be included within the scope of the present invention.

Claims

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

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

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

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

5. The pressure-sensitive adhesive film according to claim 1 , wherein the inorganic particles having a refractive index of 1.5 or more contain zinc-based oxide.

6. The pressure-sensitive adhesive film according to claim 5 , wherein the zinc-based oxide is contained in an amount of 95% by weight 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-based oxide has an average particle size (D50) of 10 nm to 300 nm.

8. The adhesive film according to claim 5 , wherein the zinc-based oxide is a mixture of zinc-based 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 contained in the adhesive film in an amount of 0.01% by weight to 5% by weight.

10. The pressure-sensitive adhesive film according to claim 1 , further comprising inorganic particles having a refractive index of less than 1.

5.

11. The pressure-sensitive adhesive film according to claim 10, wherein the inorganic particles having a refractive index of less than 1.5 contain silica.

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

13. The adhesive film according to claim 10, wherein the adhesive film is formed from a composition for an adhesive film, the composition comprising 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.

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

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

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

17. The adhesive film according to claim 13 , wherein the composition for an adhesive film further contains organic nanoparticles.

18. The adhesive film according to claim 17, wherein the organic nanoparticles contain core-shell type organic nanoparticles that satisfy the following mathematical formula 1: [Equation 1] Tg(c)<Tg(s) (In the above formula 1, Tg(c) is the glass transition temperature (unit: ° C.) of the core, and Tg(s) is the glass transition temperature (unit: ° C.) of the shell.)

19. An optical member comprising the pressure-sensitive adhesive film according to claim 1 .

20. An optical display device comprising the adhesive film according to any one of claims 1 to 18.

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