Adhesive film, optical member comprising same, and optical display device comprising same

Abstract

Provided are an adhesive film, an optical member comprising same, and an optical display device comprising same, the adhesive film comprising a cured product of a composition for an adhesive film including a polymer of (meth)acrylic-based monomer mixtures. The adhesive film has a peel strength of 400 gf / 25 mm or more with respect to a polyethylene terephthalate film having an antistatic layer, which is measured after a specimen in which the adhesive film is laminated on the polyethylene terephthalate film having the antistatic layer is left at 60 ℃ and 93% relative humidity for 500 hours. The adhesive film has a storage modulus of 10 to 100 kPa at 25 ℃. The adhesive film has a resistance change rate of 1% or less according to Equation 1.

Description

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

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

[0002] As interest in foldable optical displays grows, the adhesive films used in these devices are also required to possess superior foldable properties. As the usage environments for foldable optical displays, particularly foldable phones, diversify, foldable phones can also be used underwater. Waterproofing is essential for underwater use.

[0003] Applying a barrier layer or film capable of blocking moisture penetration to a foldable optical display device may be considered. However, conventional barrier layers or films have high modulus, which can cause them to experience stress during folding. Therefore, it may be desirable to use an adhesive film that offers both excellent foldability and waterproofing. Waterproofing requires high peel strength after long-term exposure to high temperature and high humidity, as well as low resistance change after long-term exposure to high temperature and high humidity.

[0004] The background technology of the present invention is disclosed in Japanese Patent Application Laid-Open No. 2013-072951, etc.

[0005] Provides an adhesive film that provides excellent folding properties, high peel strength after long-term storage at high temperature and high humidity, and low resistance change rate after long-term storage at high temperature and high humidity.

[0006] Provides an adhesive film that provides excellent waterproofing properties.

[0007] Provides an adhesive film with high adhesion to an adherend.

[0008] 1. According to one embodiment, the adhesive film comprises a cured product of a composition for an adhesive film comprising a polymer of a (meth)acrylic monomer mixture, wherein the adhesive film has a peel strength of 400 gf / 25 mm or more for a polyethylene terephthalate film having an antistatic layer, measured after leaving a specimen on which the adhesive film is laminated at 60° C. and 93% relative humidity for 500 hours, and the adhesive film has a storage modulus of 10 to 100 kPa at 25° C., and the adhesive film has a resistance change rate of 1% or less in the following equation 1:

[0009] [Formula 1]

[0010] Resistance change rate = |(R2 - R1) / R1 | × 100

[0011] (In the above equation 1,

[0012] R1 is an indium tin oxide film; a first silver layer and a second silver layer laminated on each end of the upper surface of the indium tin oxide film; an adhesive film covering a portion of the first silver layer, a portion of the second silver layer, and the indium tin oxide film positioned between the first silver layer and the second silver layer; and a release film covering the adhesive film; a line resistance (unit: Ω) measured between the first silver layer and the second silver layer for a specimen having

[0013] R2 is the line resistance (unit: Ω) measured between the first silver layer and the second silver layer after leaving the above specimen at 60°C and 95% relative humidity for 500 hours.

[0014] 2. In 1, the adhesive film is laminated on a polyethylene terephthalate film having an antistatic layer, and the peeling force of the adhesive film on the polyethylene terephthalate film having an antistatic layer, measured after leaving the adhesive film on the polyethylene terephthalate film having an antistatic layer at 25°C for 30 minutes, may be 600 gf / 25 mm or more.

[0015] In 3.1-2, the composition for the adhesive film may include a polymer of the (meth)acrylic monomer mixture, a (meth)acrylate having a carboxylic acid group, a photoinitiator, and a crosslinking agent having an alkylene oxide group and a (meth)acrylate group.

[0016] In 4.1-3, the (meth)acrylate having the carboxylic acid group may be a beta-carboxylalkyl (meth)acrylate.

[0017] In 5.1-4, the alkylene oxide group may be an ethylene oxide group or a propylene oxide group.

[0018] In 6.1-5, the crosslinking agent having the alkylene oxide group and the (meth)acrylate group may have 2 to 6 (meth)acrylate groups.

[0019] In 7.1-6, the monomer mixture may include a (meth)acrylic monomer having an alkyl group and a (meth)acrylic monomer having a hydroxyl group.

[0020] In 8.1-7, the total amount of the (meth)acrylic monomer having the alkyl group and the (meth)acrylic monomer having the hydroxyl group may be included in the monomer mixture at 95 wt% or more.

[0021] In 9.1-8, the (meth)acrylic monomer having the alkyl group may be included in the monomer mixture in an amount of 60 to 90 wt% and the (meth)acrylic monomer having the hydroxyl group may be included in an amount of 10 to 40 wt%.

[0022] In 10.1-9, the monomer mixture may not include a (meth)acrylic monomer having a carboxylic acid group.

[0023] In 11.1-10, the composition for the adhesive film is

[0024] 100 parts by weight of a polymer of the above (meth)acrylic monomer mixture,

[0025] 0.1 to 5 parts by weight of (meth)acrylate having the above carboxylic acid group,

[0026] 0.001 to 5 parts by weight of the above photoinitiator, and

[0027] It may include 0.01 to 0.5 parts by weight of a crosslinking agent having the above alkylene oxide group and (meth)acrylate group.

[0028] In 12.1-11, the adhesive film may not contain organic nanoparticles.

[0029] In 13.1-12, the adhesive film may have a substrate adhesion of 400 gf / 25 mm or more.

[0030] According to one embodiment, the optical display device includes the adhesive film.

[0031] An adhesive film was provided that provided excellent folding properties, high peel strength after long-term storage at high temperature and high humidity, and low resistance change rate after long-term storage at high temperature and high humidity.

[0032] We provide an adhesive film that provides excellent waterproofing properties.

[0033] An adhesive film with high adhesion to the adherend was provided.

[0034] Figure 1 is a cross-sectional view of a specimen for measuring line resistance.

[0035] Figure 2 is a plan view of a specimen for measuring line resistance.

[0036] Below, embodiments of the present application are described in more detail. However, the technology disclosed in this application is not limited to the embodiments described herein and may be embodied in other forms. However, the embodiments introduced herein are provided to ensure that the disclosed content is thorough and complete and to sufficiently convey the spirit of the present application to those skilled in the art.

[0037] The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

[0038] In this specification, "glass transition temperature of a homopolymer" may refer to a glass transition temperature (Tg) measured using a DSC Discovery from TA Instrument for a homopolymer of a target monomer. Specifically, for a homopolymer of a target monomer, the temperature is increased to 180°C at a heating rate of 20°C / min, slowly cooled to -100°C, and then increased to 100°C at a heating rate of 10°C / min. After obtaining data on an endothermic transition curve, the inflection point of the endothermic transition curve may be determined as the glass transition temperature.

[0039] As used herein, “(meth)acrylic” means acrylic and / or methacrylic.

[0040] In this specification, “weight average molecular weight” may be a value obtained by polystyrene conversion in gel permeation chromatography.

[0041] When a numerical range is described in this specification, “X to Y” means X or more and Y or less (X≤ and ≤Y).

[0042] According to one embodiment, an adhesive film is provided that provides excellent foldability, high peel strength after long-term storage at high temperature and high humidity, and low resistance change rate after long-term storage at high temperature and high humidity. According to one embodiment, an adhesive film with high adhesion to an adherend is provided. The adhesive film can be used in optical display devices that require excellent waterproofing while providing excellent foldability.

[0043] According to one embodiment, the adhesive film has a peel strength of 400 gf / 25 mm or more with respect to a polyethylene terephthalate film having an antistatic layer, which is measured after leaving a specimen on which the adhesive film is laminated at 60° C. and 95% relative humidity for 500 hours. In the above range, an optical display device having the adhesive film has an excellent waterproof function, thereby expanding the range of applications of the adhesive film and the optical display device. For example, the peel strength may be 400, 500, 600, 700, 800, 900, 1000 gf / 25 mm, for example, 400 to 1000 gf / 25 mm, 400 to 800 gf / 25 mm.

[0044] Here, the "antistatic layer" may be a coating layer manufactured by a conventional method known to those skilled in the art. For example, the antistatic layer may include, but is not limited to, an ionic liquid, a conductive polymer, etc.

[0045] The adhesive film has a storage modulus of 10 to 100 kPa at 25°C. Within this range, the optical display device comprising the adhesive film may exhibit excellent foldability. For example, the storage modulus may be 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100 kPa, for example, 11 to 90 kPa.

[0046] The adhesive film has a resistance change rate of 1% or less as shown in Equation 1 below: Within the resistance change rate range, an optical display device including the adhesive film can operate without malfunction even after long-term exposure to high temperature and high humidity, thereby exhibiting excellent waterproofing properties. For example, the resistance change rate may be 0 to 1%:

[0047] [Formula 1]

[0048] Resistance change rate = |(R2 - R1) / R1| × 100

[0049] (In the above equation 1,

[0050] R1 is an indium tin oxide film; a first silver layer and a second silver layer laminated on each end of the upper surface of the indium tin oxide film; an adhesive film covering a portion of the first silver layer, a portion of the second silver layer, and the indium tin oxide film positioned between the first silver layer and the second silver layer; and a release film covering the adhesive film; a line resistance (unit: Ω) measured between the first silver layer and the second silver layer for a specimen having

[0051] R2 is the line resistance (unit: Ω) measured between the first silver layer and the second silver layer after leaving the above specimen at 60°C and 93% relative humidity for 500 hours.

[0052] According to one embodiment, the adhesive film is laminated on a polyethylene terephthalate film having an antistatic layer, and a peel strength of the adhesive film relative to the polyethylene terephthalate film having an antistatic layer, measured after leaving the adhesive film on the polyethylene terephthalate film having an antistatic layer for 30 minutes at 25°C, may be 600 gf / 25 mm or more, for example, 600, 700, 800, 900, 1000 gf / 25 mm, for example, 600 to 1000 gf / 25 mm.

[0053] According to one embodiment, the adhesive film may have a substrate adhesion strength of 400 gf / 25 mm or greater. Within this range, the adhesive film may adhere to the adherend in a short period of time, thereby enhancing reliability. For example, the substrate adhesion strength may be 400 to 800 gf / 25 mm. Here, "substrate adhesion strength" refers to the adhesion strength used for barrier films and for PET.

[0054] The above adhesive film is a photocurable transparent adhesive (OCA) and can be used in a foldable optical display device.

[0055] The adhesive film may have a thickness of 100 μm or less. Within this range, the adhesive film may provide a thin thickness, sufficiently providing a thinning effect even when used in a foldable optical display device. Specifically, the adhesive film may have a thickness of greater than 0 μm and less than or equal to 100 μm, or from 10 μm to 80 μm.

[0056] The adhesive film may have a storage modulus of 200 kPa or less at -20°C, for example, 0.1 to 200 kPa, or 50 to 200 kPa. Within this range, the adhesive film may help provide excellent foldable properties under a wide range of conditions.

[0057] The adhesive film may have a storage modulus of 200 kPa or less at 60°C, for example, 1 to 200 kPa, 10 to 100 kPa. In this range, it may help provide excellent foldable properties under a wide range of conditions.

[0058] The adhesive film may have a storage modulus ratio of -20°C storage modulus: 60°C storage modulus of 1:0.1 to 1:0.8, specifically 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, for example 1:0.2 to 1:0.5. In the above range, it may be easy to provide excellent foldable properties under a wide range of conditions.

[0059] The adhesive film may have a haze of 1% or less, for example, 0% to 1%, in the visible light range, for example, at a wavelength of 380 to 780 nm. In this range, the adhesive film may be used in an optical display device.

[0060] The above adhesive film is a (meth)acrylic adhesive film, and in one specific example, may be a pressure sensitive adhesive (PSA).

[0061] The above adhesive film comprises a cured product of a composition for an adhesive film comprising a polymer of a (meth)acrylic monomer mixture.

[0062] Specifically, the composition for the adhesive film comprises a polymer of the (meth)acrylic monomer mixture, a (meth)acrylate having a carboxylic acid group, a photoinitiator, and a crosslinking agent having an alkylene oxide group and a (meth)acrylate group. A composition comprising a (meth)acrylate having a carboxylic acid group; and a crosslinking agent having an alkylene oxide group and a (meth)acrylate group can easily provide the effects described above.

[0063] In one specific embodiment, the adhesive film may include a photocurable product of the composition for the adhesive film.

[0064] The polymer of the above (meth)acrylic monomer mixture can easily form a matrix of an adhesive film and provide the above-described peel strength and resistance change rate.

[0065] The above monomer mixture may include a (meth)acrylic monomer having an alkyl group and a (meth)acrylic monomer having a hydroxyl group. In one specific example, the total amount of the (meth)acrylic monomer having an alkyl group and the (meth)acrylic monomer having a hydroxyl group may be comprised in the monomer mixture at least 95 wt%, for example, 99 to 100 wt%, or 100 wt%. Within the above range, it may be easy to provide the above-described effects of the present invention.

[0066] The (meth)acrylic monomer having an alkyl group can be selected from among (meth)acrylic monomers having an unsubstituted alkyl group of a straight or branched chain having 1 to 20 carbon atoms. The (meth)acrylic monomer having a straight or branched alkyl group having 1 to 20 carbon atoms is a (meth)acrylic acid ester having an unsubstituted straight or branched alkyl group having 1 to 20 carbon atoms in the ester moiety, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, iso-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, heptyl (meth)acrylate, n-octyl (meth)acrylate, iso-octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate. It may contain more than one type.

[0067] According to one embodiment, the (meth)acrylic monomer having the alkyl group may be included in the monomer mixture in an amount of 60 wt% or more, specifically 60 to 90 wt%, for example 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 wt%, more specifically 70 to 85 wt%. In the above range, it may be easy to form a matrix of an adhesive film.

[0068] According to one embodiment, the (meth)acrylic monomer having an alkyl group may include a (meth)acrylic monomer having a glass transition temperature of the homopolymer of -50°C or lower. The (meth)acrylic monomer having a glass transition temperature of the homopolymer of -50°C or lower may facilitate reaching the above-described storage modulus and peel strength by lowering the glass transition temperature of the polymer. The (meth)acrylic monomer may have a glass transition temperature of the homopolymer of specifically -80°C to -50°C. The 'glass transition temperature of the homopolymer of the (meth)acrylic monomer' may be measured by a conventional method known to those skilled in the art or may be obtained by referring to a commercial catalog.

[0069] In one specific example, the (meth)acrylic monomer having an alkyl group and a glass transition temperature of the homopolymer of -50°C or lower may be included in the monomer mixture in an amount of 60 wt% or more, specifically 60 to 90 wt%, for example 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 wt%, more specifically 70 to 85 wt%. In the above range, it may be easy to lower the glass transition temperature of the polymer.

[0070] A (meth)acrylic monomer having a glass transition temperature of -50°C or lower of the homopolymer may be contained as one or more types, for example, two or more types, in the monomer mixture.

[0071] The (meth)acrylic monomer having the above hydroxyl group can be selected from among (meth)acrylic monomers having a straight-chain or branched-chain alkyl group having 1 to 20 carbon atoms and having one or more hydroxyl groups. For example, a (meth)acrylic monomer having a hydroxyl group is a (meth)acrylic acid ester having an alkyl group having 1 to 20 carbon atoms and having one or more hydroxyl groups in the ester moiety, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 1,4-cyclohexanedimethanol mono (meth)acrylate, 1-chloro-2-hydroxypropyl (meth)acrylate, diethylene glycol mono (meth)acrylate, 2-hydroxy-3-phenyloxypropyl (meth)acrylate, 4-hydroxycyclopentyl (meth)acrylate, It may contain at least one type of 4-hydroxycyclohexyl (meth)acrylate.

[0072] According to one embodiment, the (meth)acrylic monomer having a hydroxyl group may be included in the monomer mixture in an amount of 40 wt% or less, specifically 10 to 40 wt%, for example 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 wt%, and more specifically 15 to 30 wt%. In the above range, it may be easy to obtain the above-described peel strength and storage modulus.

[0073] According to one embodiment, the monomer mixture may not include a (meth)acrylic monomer having a carboxylic acid group. That is, the content of the (meth)acrylic monomer having a carboxylic acid group in the monomer mixture may be 0 wt%. An adhesive film formed with a composition including a polymer of a monomer mixture including a (meth)acrylic monomer mixture having a carboxylic acid group may have an increased storage modulus at a temperature such as 25°C. For example, the (meth)acrylic monomer having a carboxylic acid group may be a (meth)acrylate having a carboxylic acid group described below.

[0074] The above polymer may have a glass transition temperature of -50°C or lower, for example, -70, -65, -60, -55, -50°C, for example, from -70°C to -50°C. In the above range, it may be easy to reach the above storage modulus and peel strength.

[0075] The above polymer may have a weight average molecular weight of 800,000 g / mol or more, for example, 800,000, 850,000, 900,000, 950,000, 1,000,000, 1,050,000, 1,100,000, 1,150,000, 1,200,000, 1,250,000, 1,300,000, 1,350,000, 1,400,000, 1,450,000, 1,500,000 g / mol, 800,000 to 1,500,000 g / mol, 1,000,000 to 1,300,000 g / mol. In the above range, it may be easy to reach the above storage modulus and peel strength.

[0076] The polymer may be prepared by polymerizing, for example, photopolymerizing, the monomer mixture. In one specific example, the polymer may be a partially polymerized product or a fully polymerized product of the monomer mixture. The partially polymerized product may be a product in which the monomer mixture is not fully polymerized with a degree of polymerization of 100% but is polymerized less than 100%, and may be a mixture of a (meth)acrylic polymer formed from the monomer mixture and unreacted (meth)acrylic monomers remaining. The fully polymerized product may be a product in which the monomer mixture is fully polymerized with a degree of polymerization of 100% and contains only a (meth)acrylic copolymer.

[0077] The above polymer can be prepared by polymerizing the above monomer mixture using a polymerization method. The polymerization can be performed by a conventional method known to those skilled in the art. For example, it can be performed by adding a predetermined amount of a photoinitiator to the above monomer mixture and irradiating it with light.

[0078] The crosslinking agent having the above alkylene oxide group and (meth)acrylate group may be a crosslinking agent having *-(-RO-)-* (* is a linking moiety, and R is a substituted or unsubstituted alkylene group having 2 to 5 carbon atoms) as an alkylene oxide group.

[0079] The crosslinking agent having the above alkylene oxide group and (meth)acrylate group can be included together with the (meth)acrylate having a carboxylic acid group described below, thereby helping to secure the above-described peeling strength and reduce the resistance change rate even after the adhesive film is left at high temperature and high humidity for a long period of time.

[0080] The above-mentioned alkylene oxide group having 2 to 5 carbon atoms may be an ethylene oxide group or a propylene oxide group, but is preferably an ethylene oxide group. Through this, an adhesive film can be formed through a crosslinking reaction with the polymer, and foldability can be improved.

[0081] The crosslinking agent having the above alkylene oxide group and (meth)acrylate group may include 2 to 6, preferably 3 to 5, (meth)acrylate groups which are photocurable functional groups.

[0082] The crosslinking agent having the above alkylene oxide group and (meth)acrylate group can be used as a commercially available product.

[0083] The crosslinking agent having the above alkylene oxide group and (meth)acrylate group may be included in an amount of 0.01 to 0.5 parts by weight, for example, 0.01, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5 parts by weight, for example, 0.05 to 0.3 parts by weight, 0.05 to 0.2 parts by weight, based on 100 parts by weight of the polymer. In the above range, it may be easy to increase the peeling strength at high temperature and high humidity and to lower the resistance change rate while preventing an excessive increase in the storage modulus of the adhesive film.

[0084] The (meth)acrylate having the carboxylic acid group is not included in the monomer mixture, but is included in the composition for the adhesive film. When the (meth)acrylate having the carboxylic acid group is included in the monomer mixture and is present in the polymer, the storage modulus of the adhesive film can be increased.

[0085] The (meth)acrylate having the above carboxylic acid group can self-cure or cure together with the alkylene oxide group and the (meth)acrylate group during photocuring of the composition for an adhesive film including a crosslinking agent having the above alkylene oxide group and the (meth)acrylate group, thereby providing high cohesion and securing resistance to moisture permeation, thereby increasing peeling strength and reducing resistance change rate when the adhesive film is left at high temperature and high humidity for a long period of time.

[0086] The (meth)acrylate having the above carboxylic acid group may include carboxylalkyl (meth)acrylates, such as beta-carboxylethyl (meth)acrylate, etc. In this case, the 'alkyl' may be an alkyl group having 1 to 5 carbon atoms.

[0087] The (meth)acrylate having the above carboxylic acid group may be included in an amount of 0.1 to 5 parts by weight, for example, 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or 5 parts by weight, for example, 1 to 5 parts by weight, based on 100 parts by weight of the above polymer. In the above range, when the adhesive film is left at high temperature and high humidity for a long period of time, the peeling strength may be high and the resistance change rate may be low.

[0088] The photoinitiator can photocure the composition for an adhesive film to form an adhesive film or, if the polymer is a partial polymer, completely polymerize the remaining (meth)acrylic monomer.

[0089] Any photoinitiator that can induce a polymerization reaction or curing reaction by generating radicals during a photocuring process such as by light irradiation can be used. For example, the photoinitiator may be a photoradical initiator, such as a benzoin-based, hydroxy ketone-based, amino ketone-based or phosphine oxide-based photoinitiator, and 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'-diethoxy acetophenone, 2,2'-dibutoxy acetophenone, 2-hydroxy-2-methyl propiophenone, pt-butyl trichloro acetophenone, pt-butyl dichloro acetophenone, 4-chloro acetophenone, 2,2'-dichloro-4-phenoxy acetophenone, and dimethyl anino Acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholino phenyl)-butan-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzophenone, p-phenylbenzophenone, 4,4nonsidiethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, Examples thereof include 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethylamino benzoic acid ester, oligo[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone], and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide.

[0090] The photoinitiator may be included in an amount of 0.0001 to 5 parts by weight, specifically 0.001 to 3 parts by weight, or 0.001 to 1 part by weight, based on 100 parts by weight of the polymer. Within this range, the curing reaction can proceed completely, the residual amount of photoinitiator can be prevented from remaining and lowering the light transmittance of the adhesive film, and the generation of bubbles can be reduced and excellent reactivity can be achieved.

[0091] The composition for the above adhesive film, i.e., the adhesive film, may further include a silane coupling agent.

[0092] A silane coupling agent can further enhance the peel strength of the adhesive film. The silane coupling agent may include any conventional silane coupling agent known to those skilled in the art. For example, the silane coupling agent may include, but is not limited to, epoxy group-containing silane coupling agents such as glycidoxypropyltrimethoxysilane and glycidoxypropylmethyldimethoxysilane.

[0093] The above silane coupling agent may be included in an amount of 0.01 to 5 parts by weight per 100 parts by weight of the polymer. Within the above range, the peeling strength may be improved.

[0094] According to one embodiment, the composition for the adhesive film may be a solvent-free type that does not contain a solvent.

[0095] According to another embodiment, the composition for the adhesive film may further include a solvent. The solvent can make the surface of the adhesive film uniform when forming a thin adhesive film, particularly having a thickness of 20 μm or less, from the composition. The solvent may be any common solvent known to those skilled in the art without limitation. For example, the solvent may be an organic solvent such as ethyl acetate, methyl ethyl ketone, or methyl isobutyl ketone, but is not limited thereto. The composition may have a solid content of 50 wt% or less, for example, 20 wt% or less.

[0096] The composition for the adhesive film, i.e., the adhesive film, may further include additives. The additives may provide additional functions to the adhesive film. Specifically, the additives may include, but are not limited to, one or more of a UV absorber, a reaction inhibitor, an adhesion enhancer, a thixotropic agent, a conductivity agent, a colorant regulator, a stabilizer, an antioxidant, a leveling agent, and an antistatic agent. The content of the additives in the composition, i.e., the adhesive film, may be appropriately selected within a range that does not affect the effects of the present invention.

[0097] According to one embodiment, the adhesive film may not include organic nanoparticles. Here, the "organic nanoparticles" may be organic nanoparticles known to provide foldability, such as core-shell nanoparticles. The adhesive film may provide excellent foldability even without including organic nanoparticles.

[0098] According to another embodiment, the adhesive film may further comprise the organic nanoparticles.

[0099] The adhesive film can be formed using the adhesive film composition described above. Specifically, the adhesive film can be manufactured by applying the adhesive film composition to a release film and then photocuring it. The photocuring is performed in an oxygen-free environment using a low-pressure lamp at a wavelength of 300 nm to 400 nm and an irradiation dose of 400 mJ / cm. 2 3000mJ / cm 2 It may include the investigation of the adhesive film, but the investigation amount and investigation wavelength may be changed depending on the thickness of the adhesive film and the investigation conditions.

[0100] Hereinafter, an optical member of one embodiment of the present invention will be described.

[0101] The optical member 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. Accordingly, the optical member has good bending and / or folding properties and can be used in a foldable display device.

[0102] In one embodiment, the optical film provides a certain optical function of a display device, such as polarization, optical compensation, display image quality improvement, and / or conductivity, and the optical film may be a window film, a window, a polarizing plate, a color filter, a phase difference film, an elliptically polarizing film, a reflective polarizing film, an antireflection film, a compensation film, a brightness enhancement film, an alignment film, a light diffusion film, a glass shatter prevention film, a surface protection film, an OLED device barrier layer, a plastic LCD substrate, a transparent electrode film including ITO (indium tin oxide), FTO (fluorinated tin oxide), AZO (aluminum dopped zinc oxide), CNT (carbon nanotube), Ag nanowire, graphene, etc. The method for manufacturing the optical film can be easily manufactured by a person having ordinary skill in the art to which the present invention pertains.

[0103] For example, a touch panel can be formed by attaching an adhesive film to a window or optical film using a touchpad. Alternatively, the adhesive film can be applied to a conventional polarizing film.

[0104] 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 of the display device. For example, the display device can include a window film, etc. The window film can include the optical member and a window coating layer (e.g., a silicone-based coating layer) formed on the optical member. Specifically, the optical film can be a film having a total light transmittance of 90% or more in the visible light region and formed of one or more resins from among a cellulose resin including triacetyl cellulose, 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 polymethyl methacrylate, etc., a cyclic olefin 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, and more specifically 30 µm to 50 µm. Within the above range, it may be used as a support layer of a display device.

[0105] The optical member may be a two-layer optical member comprising an optical film and an adhesive film formed on one surface of the optical film. Alternatively, the optical member may be a three-layer or more film laminate comprising two or more optical films, at least two of which are laminated using the adhesive film of the present invention.

[0106] The optical display device of the present invention includes the adhesive film of the present invention.

[0107] An optical display device may include a light-emitting element display device, such as an organic light-emitting element display device, a liquid crystal display device, etc. An optical display device may include a flexible display device. However, an optical display device may also include a non-flexible display device.

[0108]

[0109] Hereinafter, the composition and operation of the present invention will be described in more detail through examples of the present invention. However, the following examples are intended to aid understanding of the present invention, and the scope of the present invention is not limited to the following examples.

[0110]

[0111] Example 1

[0112] 100 parts by weight of a monomer mixture containing 80 parts by weight of 2-ethylhexyl acrylate (2-EHA) and 20 parts by weight of 4-hydroxybutyl acrylate (4-HBA) and 0.05 parts by weight of Irgacure 651 (2,2-dimethoxy-2-phenylacetophenone, BASF) as an initiator were well mixed in a reactor. After the dissolved oxygen in the reactor was exchanged with nitrogen gas, the mixture was partially polymerized by irradiating it with ultraviolet rays using a low-pressure mercury lamp, thereby producing a polymer (viscous liquid having a viscosity of 5,000 cps at 25°C).

[0113] To the above viscous liquid, based on 100 parts by weight of the solid content of the polymer, 0.3 parts by weight of Irgacure 127, 0.1 parts by weight of Irgacure 651, 0.1 parts by weight of a crosslinking agent MF-001 having an alkylene oxide group and a (meth)acrylate group, and 0.5 parts by weight of beta-carboxyethyl acrylate were added and mixed to prepare a composition for an adhesive film.

[0114] The composition for the manufactured adhesive film is applied to a first release PET (polyethylene terephthalate) film, which is a release film, and then covered with a second release PET film, and then exposed to ultraviolet light at 2000 mJ / cm 2 By investigating the amount of light, an adhesive sheet of a first heterogeneous PET film - an adhesive film having a thickness of 50 ㎛ - a second heterogeneous PET film was manufactured.

[0115]

[0116] Examples 2 to 5

[0117] In Example 1, an adhesive film was manufactured in the same manner as in Example 1, except that the content of beta-carboxyethyl acrylate, the content of the crosslinking agent having an alkylene oxide group and a (meth)acrylate group were changed as shown in Table 1 below. In Table 1 below, the unit is parts by weight, and '-' means that the corresponding component is not included.

[0118]

[0119] Comparative Examples 1 and 2

[0120] In Example 1, an adhesive film was manufactured in the same manner as in Example 1, except that the content of beta-carboxyethyl acrylate, the content of a crosslinking agent having an alkylene oxide group and a (meth)acrylate group were changed as shown in Table 1 below, and the content of each component in the composition for an adhesive film was changed. In Table 1 below, the unit is parts by weight, and '-' means that the corresponding component is not included.

[0121]

[0122] The composition of the adhesive films of the examples and comparative examples is shown in Table 1 below. The physical properties of the adhesive films of the examples and comparative examples were evaluated in Table 1 below.

[0123] (1) Initial peel strength: After peeling off one of the release PET films from among the adhesive sheets manufactured in the examples and comparative examples, a polyurethane film (thickness: 25㎛, NK Company) was laminated to the peeled surface, cut to a size of width x length (2.5cm x 10cm), peeled off the remaining release PET film, and then adhered to a polyethylene terephthalate film (TAK) having an antistatic layer, thereby manufacturing a specimen laminated in the order of polyethylene terephthalate film having an antistatic layer - adhesive film - polyurethane film. After preparing the specimen and leaving it at 25°C for 30 minutes, the specimen was fixed to a TA (Texture Analyzer) Instrument for measuring peel strength, and the peel strength was measured when peeling an adhesive film and a polyurethane film laminate from a polyethylene terephthalate film having an antistatic layer at 25°C at a peel speed of 300 mm / min and a peel angle of 180°.

[0124] (2) High-temperature, high-humidity peel strength: Specimens were prepared using the same method as in (1). The prepared specimens were left at 60°C and 95% relative humidity for 500 hours. Then, the peel strength was measured using the same method as in (1).

[0125] (3) Resistance change rate: By removing the release films on both sides from the adhesive sheets manufactured in the examples and comparative examples, an adhesive film was obtained, and using the obtained adhesive film, indium tin oxide film, silver paste (including a paste for forming a silver layer and silver powder), and release PET film, a specimen for measuring resistance in Figs. 1 and 2 was manufactured.

[0126] Referring to FIGS. 1 and 2, an indium tin oxide film (2) is bonded to a glass plate (1) with an adhesive, and the indium tin oxide film (2) (thickness: 150 μm); a first silver layer (3) and a second silver layer (4) are laminated on both ends of the upper surface of the indium tin oxide film (2), respectively; an adhesive film (5) (thickness: 150 μm) covering a portion of the first silver layer (3), a portion of the second silver layer (4), and the indium tin oxide film (2) positioned between the first silver layer and the second silver layer; For a specimen having a PET film (6) (thickness: 50 ㎛) that covers the adhesive film (5), the line resistance (unit: Ω, R1) between the first silver layer (3) and the second silver layer (4) and between the measuring points (A) and (B) was measured using a resistance meter (7) (3244-60, Hioki).

[0127] After the above specimen was left at 60°C and 93% relative humidity for 500 hours, the line resistance (unit: Ω, R2) measured between the first silver layer and the second silver layer was measured using the same method as above.

[0128] The resistance change rate was measured using the measured R1 and R2 and the above equation 1.

[0129] (4) Adhesion to substrate: A specimen having a laminated structure of the polyurethane film / adhesive film / polyethylene terephthalate film with an antistatic layer described above was manufactured, and the peeling force was measured when the adhesive film was peeled from the polyethylene terephthalate film with an antistatic layer. The peeling force was measured at 25°C and a peeling speed of 50 mm / min in a T-Peel structure.

[0130] (5) Storage modulus: The storage modulus was measured under auto strain conditions at a shear rate of 1 rad / sec and a strain of 1% using a rheometer (TA ARES G2), a dynamic viscoelasticity measuring device. The adhesive films manufactured in the examples and comparative examples were laminated in multiple layers to produce samples with a thickness of 800 ㎛. The laminates were perforated with a perforator having a diameter of 8 mm to use as specimens. A force of 1.0 N of normal force was applied to the specimen using an 8 mm jig, and the temperature was increased at a temperature of 5°C / min from -60°C to 90°C, and the measurement was performed, and the storage modulus was obtained at 25°C.

[0131] (6) Foldability: The adhesive films were obtained by separating the release films on both sides from the adhesive sheets manufactured in the examples and comparative examples. The adhesive films were placed between two 50 ㎛ thick polyethylene terephthalate (PET) films that had been corona-treated, and the corona-treated side of the PET film was made to come into contact with the adhesive films and attached with a roller. Then, the films were aged at room temperature for 12 hours and cut into a size of width X length (70 mm X 140 mm) to prepare specimens. The cut specimens were fixed to a bendability evaluation device (CFT-200, Covotech) using an adhesive (4965, Tesa Co.), and the length (140 mm) of the specimen was bent at a speed of 30 cycles per minute at 25°C so that the radius of curvature became 3 mm (one cycle is defined as bending and unfolding the adhesive film in half once). When bending was repeated as 1 cycle, the first number of cycles at which cracks appeared visually in the polyethylene terephthalate film was measured. An adhesive film with a large minimum number of cycles is an adhesive film that can easily relax the stress of the polyethylene terephthalate film caused by bending. If the first number of cycles is 100,000 or more, it is OK, and if it is less than 100,000, it is NG.

[0132] Example Comparative Example 1234512 Monomer Mixture 2-EHA808080808080804-HBA20202020200202-HEA00000200 Beta-CEA0000000 Composition IC1270.30.30.30.30.30.30.3 IC6510.10.10.10.10.10.10.1MF-0010.10.10.10.10.10.10.10.1 Beta-CEA0.5123500AA0000003ACMO0000050 Initial Peeling Strength (gf / 25mm) 750790795800807930850 After High Temperature and High Humidity Peeling strength (gf / 25mm) 450 465 480 491 494 340 630 Resistance change rate (%) 00000003 Adhesion to substrate (gf / 25mm) 410 430 4 ...

[0133]

[0134] *In Table 1 above,

[0135] AA: Acrylic acid,

[0136] 2-HEA: 2-hydroxyethyl acrylate

[0137] ACMO: Acryloylmorpholine.

[0138]

[0139] As shown in Table 1 above, the adhesive film of the example provided the effects of excellent folding properties, high peel strength after long-term storage at high temperature and high humidity, and low resistance change rate after long-term storage at high temperature and high humidity.

[0140] On the other hand, the adhesive film of the comparative example did not provide all of the above-described effects.

[0141]

[0142] Simple modifications or changes of the present invention can be easily implemented by a person having ordinary skill in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

Claims

1. As an adhesive film, The above adhesive film comprises a cured product of a composition for an adhesive film comprising a polymer of a (meth)acrylic monomer mixture, The adhesive film has a peel strength of 400 gf / 25 mm or more for the polyethylene terephthalate film having the antistatic layer, measured after leaving the specimen on which the adhesive film is laminated on the polyethylene terephthalate film having the antistatic layer at 60° C. and 93% relative humidity for 500 hours. The above adhesive film has a storage modulus of 10 to 100 kPa at 25°C, The above adhesive film is an adhesive film having a resistance change rate of 1% or less in the following formula 1: [Formula 1] Resistance change rate = |(R2 - R1) / R1 | × 100 (In the above equation 1, R1 is an indium tin oxide film; a first silver layer and a second silver layer each laminated on both ends of an upper surface of the indium tin oxide film; an adhesive film covering the indium tin oxide film, a part of the first silver layer, a part of the second silver layer, and a part of the first silver layer between the first silver layer and the second silver layer; and a release film covering the adhesive film; the line resistance (unit: Ω) measured between the first silver layer and the second silver layer for a specimen having the same. R2 is the line resistance (unit: Ω) measured between the first silver layer and the second silver layer after the specimen was left at 60°C and 95% relative humidity for 500 hours.

2. In the first paragraph, the adhesive film is an adhesive film in which a specimen is prepared by laminating the adhesive film on a polyethylene terephthalate film having an antistatic layer, and the adhesive film is left to stand at 25° C. for 30 minutes, and then the peeling force of the adhesive film with respect to the polyethylene terephthalate film having an antistatic layer is measured to be 600 gf / 25 mm or more.

3. In the first paragraph, the composition for the adhesive film comprises a polymer of the (meth)acrylic monomer mixture, a (meth)acrylate having a carboxylic acid group, a photoinitiator, and a crosslinking agent having an alkylene oxide group and a (meth)acrylate group.

4. An adhesive film according to claim 3, wherein the (meth)acrylate having a carboxylic acid group is beta-carboxyalkyl (meth)acrylate.

5. An adhesive film in claim 3, wherein the alkylene oxide group is an ethylene oxide group or a propylene oxide group.

6. An adhesive film in the third paragraph, wherein the crosslinking agent having an alkylene oxide group and a (meth)acrylate group has 2 to 6 (meth)acrylate groups.

7. An adhesive film according to claim 1, wherein the monomer mixture comprises a (meth)acrylic monomer having an alkyl group and a (meth)acrylic monomer having a hydroxyl group.

8. An adhesive film in claim 7, wherein the total amount of the (meth)acrylic monomer having the alkyl group and the (meth)acrylic monomer having the hydroxyl group is comprised at 95 wt% or more of the monomer mixture.

9. An adhesive film in the 7th paragraph, wherein the (meth)acrylic monomer having the alkyl group in the monomer mixture is contained in an amount of 60 to 90 wt% and the (meth)acrylic monomer having the hydroxyl group is contained in an amount of 10 to 40 wt%.

10. An adhesive film according to claim 1, wherein the monomer mixture does not contain a (meth)acrylic monomer having a carboxylic acid group.

11. In the third paragraph, the composition for the adhesive film is 100 parts by weight of a polymer of the above (meth)acrylic monomer mixture, 0.1 to 5 parts by weight of (meth)acrylate having the above carboxylic acid group, 0.001 to 5 parts by weight of the above photoinitiator, and An adhesive film comprising 0.01 to 0.5 parts by weight of a crosslinking agent having an alkylene oxide group and a (meth)acrylate group.

12. In the first paragraph, the adhesive film does not contain organic nanoparticles.

13. In the first paragraph, the adhesive film has a substrate adhesion of 400 gf / 25 mm or more.

14. An optical member comprising an adhesive film according to any one of claims 1 to 13.

15. An optical display device comprising an adhesive film according to any one of claims 1 to 13.

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