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

Abstract

The adhesive film is formed from a composition containing a monomer mixture including a monomer having a homopolymer glass transition temperature of about -50°C or less and a (meth)acrylate having a hydroxyl group, and an epoxy-based silane coupling agent, and the adhesive film has a rate of change in shear deformation rate of about 10% or less as shown in Equation 1. The adhesive film, an optical component including the adhesive, and an optical display device including the adhesive are provided.

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] In an optical display device, a plurality of optical elements are laminated with an adhesive film. Conventional adhesive films are manufactured by coating one side of a release film with a composition for an adhesive film, curing the film, and punching out the film according to the size of the optical elements.

[0003] In recent years, development of an optical display device having a foldable function has been progressing, and development of an adhesive film having a foldable function has also been progressing. The adhesive film having a foldable function shows a large difference in rheological properties compared to existing adhesive films.

[0004] Meanwhile, in relation to the durability of the adhesive film, there is a demand for an adhesive film having waterproof properties. That is, there is a growing need for an adhesive film that has a high peel strength and does not change in rheological properties compared to before immersion in water even when the adhesive film or an optical display device to which the adhesive film is attached is immersed in water, and that can reliably realize folding performance. Therefore, there is a need to develop an adhesive film that has excellent waterproof properties in addition to the existing folding performance, and has a low rate of change in peel strength even after being left at high temperature and high humidity for a long period of time, and can have excellent folding performance.

[0005] The background art of the present invention is disclosed in Korean Patent Publication No. 2017-0070370, etc. Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a pressure-sensitive adhesive film that has excellent folding properties at both low and high temperatures.

[0007] Another object of the present invention is to provide an adhesive film having excellent foldability at low temperature and high temperature even after being left at high temperature and humidity for a long period of time, and thus having excellent bending reliability.

[0008] Yet another object of the present invention is to provide an adhesive film suitable for a foldable display device that exhibits little change in peel strength, rheological properties, and durability even after exposure to high temperature and high humidity for a long period of time, compared to before exposure to high temperature and high humidity for a long period of time, and is required to be waterproof.

[0009] It is yet another object of the present invention to provide an adhesive film that has excellent waterproof properties and is suitable for a foldable display device that requires waterproof properties. [Means for solving the problem]

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

[0011] 1. The adhesive film is formed from a composition including a monomer mixture containing a monomer having a homopolymer glass transition temperature of about -50°C or less and a (meth)acrylate having a hydroxyl group, and an epoxy-based silane coupling agent, and the adhesive film has a rate of change in shear strain of about 10% or less as determined by the following formula 1:

[0012]

number

[0013] (In the above formula 1, A is the initial shear deformation rate value of the adhesive film (unit: %), B is the shear deformation rate value (unit: %) of the adhesive film obtained from the adhesive sheet obtained by leaving the adhesive film and the adhesive sheet having release polyethylene terephthalate films laminated on both sides of the adhesive film at 60°C and 95% relative humidity for 10 days and then leaving it at 25°C for 2 hours.

[0014] In 2.1, in said formula 1, A may be about 10% or more and B may be about 10% or more.

[0015] In 3.1-2, the pressure-sensitive adhesive film may have an initial modulus at -20°C of about 0.3 MPa or less.

[0016] In 4.1-3, the pressure-sensitive adhesive film may have an initial modulus at 60° C. of about 0.05 MPa or less.

[0017] In 5.1-4, the pressure-sensitive adhesive film may have a rate of change in peel strength as determined by the following formula 2 of about 20% or less.

[0018]

number

[0019] (In the above formula 2, C is the initial peel strength (unit: gf / 25 mm) of the adhesive film to the glass plate in a test piece in which a glass plate, an adhesive film, and a corona-treated polyethylene terephthalate film are laminated in this order, D is the peel strength (unit: gf / 25 mm) of the pressure-sensitive adhesive film to the glass plate after leaving the test piece at 60°C and 95% relative humidity for 10 days and then at 25°C for 2 hours.

[0020] In 6.5, in the formula 2, D may be about 400 gf / 25 mm or more.

[0021] In 7.1-6, the pressure-sensitive adhesive film may have a modulus of about 0.3 MPa or less at -20°C after being left at 60°C and 95% relative humidity for 10 days.

[0022] In 8.1-7, the PSA film may have a modulus change rate of about 10% or less as shown in the following formula 3.

[0023]

number

[0024] (In the above formula 3, E is the initial modulus of the adhesive film at 60 ° C. (unit: MPa), F is the modulus (unit: MPa) at 60°C of the adhesive film after leaving an adhesive sheet, which is an adhesive film and a release polyethylene terephthalate film laminated on both sides of the adhesive film, at 60°C and 95% relative humidity for 10 days and then at 25°C for 2 hours.

[0025] In 9.1-8, the epoxy-based silane coupling agent may be included in an amount of about 0.2 parts by weight to about 5 parts by weight based on 100 parts by weight of the monomer mixture.

[0026] In 10.1-9, the epoxy-based silane coupling agent may include one or more of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane.

[0027] In 11.1-10, the monomer having a homopolymer glass transition temperature of about -50°C or lower can have a branched chain.

[0028] In 12.1-11, the monomer having a homopolymer glass transition temperature of about -50°C or less can include a mixture of (meth)acrylic acid esters having an unsubstituted alkyl group having 3 to 20 carbon atoms and no alkylene glycol group, and (meth)acrylic acid esters having an unsubstituted alkyl group having 3 to 20 carbon atoms and an alkylene glycol group.

[0029] In 13.12, the alkyl group without an alkylene glycol group and the alkyl group with an alkylene glycol group can each have a branched chain.

[0030] In 14.12-13, the (meth)acrylic acid ester having an unsubstituted alkyl group having 3 to 20 carbon atoms and no alkylene glycol group may be included in the monomer mixture in an amount of about 50% by weight to about 80% by weight.

[0031] In 15.12-14, the (meth)acrylic acid ester having an unsubstituted alkyl group having 3 to 20 carbon atoms and an alkylene glycol group may be contained in an amount of about 10% by weight to about 40% by weight of the monomer mixture.

[0032] In 16.1-15, the monomer mixture may contain a monomer having a homopolymer glass transition temperature of about -50°C or lower in an amount of about 50% by weight to about 99% by weight, and the (meth)acrylate having a hydroxyl group in an amount of about 1% by weight to about 50% by weight.

[0033] In 17.1-16, the adhesive film may further include organic nanoparticles.

[0034] In 18.17, the organic nanoparticles may be included in an amount of about 0.1 parts by weight to about 20 parts by weight based on 100 parts by weight of the monomer mixture.

[0035] In 19.17-18, the organic nanoparticles may include core-shell nanoparticles satisfying the following formula 4:

[0036]

number

[0037] (In the above formula 4, Tg(c) is the glass transition temperature of the core (unit: ° C.), Tg(s) is the glass transition temperature of the shell (unit: °C).

[0038] The optical member of the present invention comprises an optical film and the pressure-sensitive adhesive film of the present invention formed on at least one surface of the optical film.

[0039] The optical display device of the present invention includes the pressure-sensitive adhesive film of the present invention. Effect of the Invention

[0040] The present invention can provide a pressure-sensitive adhesive film that has excellent folding properties at both low and high temperatures.

[0041] The present invention can provide a pressure-sensitive adhesive film having excellent foldability at low temperature and high temperature even after being left at high temperature and high humidity for a long period of time, and thus having excellent bending reliability.

[0042] The present invention provides an adhesive film suitable for a foldable display device that requires waterproofing, which exhibits little change in peel strength, rheological properties, and durability even after long-term storage at high temperature and high humidity compared to before long-term storage at high temperature and high humidity.

[0043] The present invention can provide an adhesive film that has excellent waterproof properties and is suitable for a foldable display device that requires waterproof properties. [Brief description of the drawings]

[0044] [Figure 1] FIG. 2 is a diagram showing an example of measurement of shear deformation rate in the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] [Best Mode for Carrying Out the Invention] The present invention may, however, be embodied in various different forms and should not be construed as being limited to the embodiments set forth herein.

[0046] As used herein, "acrylic" can mean acrylic and / or methacrylic.

[0047] As used herein, a "copolymer" can include an oligomer, polymer, or resin.

[0048] In this specification, the "average particle size" of organic nanoparticles refers to the particle size of organic nanoparticles measured in an aqueous or organic solvent using a Zetasizer nano-ZS device manufactured by Malvern and expressed as a Z-average value, and the particle size confirmed by SEM / TEM observation.

[0049] As used herein, "modulus" refers to the storage modulus (G').

[0050] In this specification, "shear deformation rate" refers to the degree of deformation when a constant shear force is applied, measured at 60°C. Referring to Figure 1, when strain applied to an adhesive film under experimental conditions at a constant force over time is measured, the strain value at 600 seconds corresponds to the shear deformation rate.

[0051] In this specification, the term "glass transition temperature of homopolymer" may refer to the glass transition temperature (Tg) measured for a homopolymer of a monomer to be measured using a DSC Discovery from TA Instruments, Inc. Specifically, the homopolymer of a monomer to be measured 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 an endothermic transition curve as data, and the inflection point of the endothermic transition curve can be determined as the glass transition temperature.

[0052] In this specification, when describing a numerical range, "X to Y" means X or more and Y or less (X≦and≦Y).

[0053] The adhesive film of the present invention has excellent folding properties at low temperatures and high temperatures, and even after being left at high temperature and high humidity for a long period of time, it exhibits excellent folding properties at low temperatures and high temperatures, and can have excellent bending reliability. The adhesive film of the present invention has little change in peel strength, rheological properties, and durability even after being left at high temperature and high humidity for a long period of time compared to before being left at high temperature and high humidity for a long period of time, and provides an adhesive film suitable for a foldable display device that requires waterproofing. Therefore, the adhesive film of the present invention has excellent waterproofing and can be appropriately used in a foldable display device that requires waterproofing.

[0054] An adhesive film according to an embodiment of the present invention will now be described.

[0055] The adhesive film of this embodiment (hereinafter referred to as "adhesive film") is formed from a composition containing a monomer mixture including a monomer having a homopolymer glass transition temperature of approximately -50°C or less and a (meth)acrylate having a hydroxyl group, and an epoxy-based silane coupling agent, and the adhesive film has a rate of change in shear deformation rate of approximately 10% or less as shown in the following formula 1.

[0056]

number

[0057] (In the above formula 1, A is the initial shear deformation rate of the adhesive film (unit: %), B is the shear deformation rate value (unit: %) of the adhesive film obtained from the adhesive sheet obtained by leaving the adhesive film and the adhesive sheet having release polyethylene terephthalate films laminated on both sides of the adhesive film at 60°C and 95% relative humidity for 10 days and then leaving it at 25°C for 2 hours.

[0058] In one specific example, the adhesive film may have a rate of change in the shear deformation rate of the above formula 1 of, for example, about 0%, 0.1%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, specifically 0% to 10%, more specifically 0% to 5%, and further for example 0.1% to 4%.

[0059] In one embodiment, the shear deformation ratios A and B in the formula 1 may each be about 10% or more, for example, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, specifically, 10% to 30%, more specifically, 18% to 25%. Within this range, there may be an effect of ensuring folding reliability.

[0060] The release polyethylene terephthalate film is a polyethylene terephthalate film whose surface in contact with the adhesive film has been subjected to release treatment (e.g., silicon treatment or fluorine treatment) and may have a thickness of 30 μm to 100 μm.

[0061] The composition for forming the adhesive film contains a monomer mixture including a monomer having a homopolymer glass transition temperature of about -50°C or less and a (meth)acrylate having a hydroxyl group. As a result, the adhesive film can have high initial peel strength and excellent folding properties at low temperatures.

[0062] In one embodiment, the adhesive film may have an initial peel strength from a glass plate of about 400gf / 25mm or more, for example, 400gf / 25mm, 450gf / 25mm, 500gf / 25mm, 550gf / 25mm, 600gf / 25mm, 650gf / 25mm, 700gf / 25mm, 750gf / 25mm, 800gf / 25mm, 850gf / 25mm, 900gf / 25mm, 950gf / 25mm, 1000gf / 25mm, specifically 400gf / 25mm to 1000gf / 25mm. In this range, the adhesive film has excellent peel strength from the adherend, and since the adhesive film is not peeled off from the adherend during folding, excellent folding properties can be realized.

[0063] The term "initial peel strength" refers to the peel strength measured before a test piece for measuring the peel strength of an adhesive film is left at 60° C. and 95% relative humidity for 10 days.

[0064] A monomer having a homopolymer glass transition temperature of about -50°C or less can reduce the initial modulus of the PSA film at low temperatures, and the PSA film can have folding properties at low temperatures. In one embodiment, the PSA film can have an initial modulus of about 0.3 MPa or less at -20°C, for example, 0.01 MPa, 0.05 MPa, 0.1 MPa, 0.15 MPa, 0.2 MPa, 0.25 MPa, 0.3 MPa, specifically, 0.01 MPa to 0.3 MPa, 0.05 MPa to 0.15 MPa. In the above range, the PSA film can ensure viscoelasticity at low temperatures, and as a result, the PSA film can have excellent folding properties at low temperatures.

[0065] A monomer having a homopolymer glass transition temperature of about -50°C or less can reduce the initial modulus of the adhesive film at high temperatures, helping the adhesive film to have folding properties at high temperatures. In one embodiment, the adhesive film may have an initial modulus of about 0.05 MPa or less at 60°C, for example, 0.01 MPa, 0.02 MPa, 0.03 MPa, 0.04 MPa, 0.05 MPa, specifically 0.01 MPa to 0.05 MPa, 0.02 MPa to 0.03 MPa. This range can ensure the viscoelasticity of the adhesive film at high temperatures, and as a result, can help the adhesive film to have excellent folding properties and recovery properties at high temperatures.

[0066] A monomer having a homopolymer glass transition temperature of about -50°C or less can make the initial shear deformation rate of the adhesive film about 10% or more, for example, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, for example, 10% to 30%, 18% to 25%. Within this range, low-temperature folding reliability can be ensured.

[0067] The monomer having a homopolymer glass transition temperature of about -50°C or less may contain a (meth)acrylic acid ester having a branched alkyl group, a branched alkylene group, a branched alkyleneoxy group, or a functional group containing these at the ester moiety of the (meth)acrylic acid ester. The branched alkyl group, the branched alkylene group, or the branched alkyleneoxy group can further reduce the modulus of the PSA film at low temperatures and further improve the folding property even at low temperatures.

[0068] The branched alkyl group may be a branched alkyl group having 3 to 20 carbon atoms, such as an ethylhexyl group, an isooctyl group, or an isodecyl group. The branched alkylene group may be a branched alkylene group having 3 to 20 carbon atoms, such as an ethylhexylene group, an isooctylene group, or an isodecylene group. The branched alkyleneoxy group may be a branched alkyleneoxy group having 3 to 20 carbon atoms.

[0069] The monomer having a homopolymer glass transition temperature of about -50° C. or less may preferably have a homopolymer glass transition temperature of, for example, -100° C., -95° C., -90° C., -85° C., -80° C., -75° C., -70° C., -65° C., -60° C., -55° C., -50° C., for example, from -100° C. to -50° C., more preferably from -80° C. to -50° C. In the above range, there may be an effect of lowering the modulus at low temperatures.

[0070] The monomer having a homopolymer glass transition temperature of about -50°C or less may be included in one or more of the monomer mixture, i.e., one or more of the monomers. The monomer having a homopolymer glass transition temperature of about -50°C or less may be included in about 50% to about 99% by weight of the monomer mixture, for example, 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%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99%, 100%, 102%, 103%, 104%, 105%, 106%, 107%, 108%, 109%, 110%, 111%, 112%, 113%, 114%, 115%, 116%, 117%, 118%, 119%, 120%, 121%, 122%, 123%, 124%, 125%, 126%, 127%, 128%, 129%, 130%, 131%, 132%, 133%, 134%, 135%, 136%, 137%, 138%, 139%, 140%, 141%, 142%, 143%, 144%, %, 70 weight%, 71 weight%, 72 weight%, 73 weight%, 74 weight%, 75 weight%, 76 weight%, 77 weight%, 78 weight%, 79 weight%, 80 weight%, 81 weight%, 82 weight%, 83 weight%, 84 weight%, 85 weight%, 86 weight%, 87 weight%, 88 weight%, 89 weight%, 90 weight%, specifically 60 weight% to 90 weight%, more specifically 70 weight% to 85 weight%. In this range, it may have an effect of lowering the modulus at low temperature and providing excellent folding property at low temperature.

[0071] In one embodiment, the monomer having a homopolymer glass transition temperature of about -50°C or less may include a mixture of (meth)acrylic acid ester having an unsubstituted alkyl group having 3 to 20 carbon atoms, preferably 3 to 10 carbon atoms, and no alkylene glycol group, and (meth)acrylic acid ester having an unsubstituted alkyl group having 3 to 20 carbon atoms, preferably 10 to 20 carbon atoms, and having an alkyl group having an alkylene glycol group. This can easily realize the effects of the present invention, and can help maintain folding ability and peel strength even after long-term storage at high temperature and humidity.

[0072] The (meth)acrylic acid ester having an unsubstituted alkyl group having 3 to 20 carbon atoms and no alkylene glycol group may include one or more of 2-ethylhexyl (meth)acrylate, isooctyl acrylate, and isodecyl acrylate. The alkyl group having no alkylene glycol group may have a branched chain.

[0073] The (meth)acrylic acid ester having an unsubstituted alkyl group having 3 to 20 carbon atoms and an alkylene glycol group may include a polyfunctional (meth)acrylate having a plurality of alkylene glycol units. The alkylene glycol units may be the same or different. The alkylene glycol units may include alkylene glycol units having 1 to 5 carbon atoms, such as ethylene glycol and propylene glycol. The alkyl group having the alkylene glycol group may have a branched chain.

[0074] The (meth)acrylic acid ester having an unsubstituted alkyl group having 3 to 20 carbon atoms and no alkylene glycol group may be included in the monomer mixture at about 50% to about 80% by weight, for example, 50% by weight, 51% by weight, 52% by weight, 53% by weight, 54% by weight, 55% by weight, 56% by weight, 57% by weight, 58% by weight, 59% by weight, 60% by weight, 61% by weight, 62% by weight, 63% by weight, 64% by weight, 65% by weight, 66% by weight, 67% by weight, 68% by weight, 69% by weight, 70% by weight, 71% by weight, 72% by weight, 73% by weight, 74% by weight, 75% by weight, 76% by weight, 77% by weight, 78% by weight, 79% by weight, 80% by weight, specifically 50% to 70% by weight. In this range, high peel strength, excellent folding property at low temperature and excellent folding property at high temperature can be ensured.

[0075] The (meth)acrylic acid ester having an unsubstituted alkyl group having 3 to 20 carbon atoms and an alkylene glycol group may be included in the monomer mixture in an amount of about 10% by weight to about 40% by weight, for example, 10% by weight, 11% by weight, 12% by weight, 13% by weight, 14% by weight, 15% by weight, 16% by weight, 17% by weight, 18% by weight, 19% by weight, 20% by weight, 21% by weight, 22% by weight, 23% by weight, 24% by weight, 25% by weight, 26% by weight, 27% by weight, 28% by weight, 29% by weight, 30% by weight, 31% by weight, 32% by weight, 33% by weight, 34% by weight, 35% by weight, 36% by weight, 37% by weight, 38% by weight, 39% by weight, 40% by weight, specifically 15% by weight to 30% by weight. In this range, the peel strength is high, and excellent folding properties at low temperatures and high temperatures can be ensured.

[0076] The (meth)acrylate having a hydroxyl group can provide peel strength to the adhesive film. The (meth)acrylate having a hydroxyl group can include a (meth)acrylate containing an alkyl group having 1 to 10 carbon atoms and containing one or more hydroxyl groups. For example, the (meth)acrylate having a hydroxyl group 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.

[0077] The (meth)acrylate having a hydroxyl group may be included in one or more of the monomer mixture, i.e., one or more of the monomer mixture. The (meth)acrylate having a hydroxyl group may be included in about 1% by weight to about 50% by weight of the monomer mixture, for example, 1% by weight, 2% by weight, 3% by weight, 4% by weight, 5% by weight, 6% by weight, 7% by weight, 8% by weight, 9% by weight, 10% by weight, 11% by weight, 12% by weight, 13% by weight, 14% by weight, 15% by weight, 16% by weight, 17% by weight, 18% by weight, 19% by weight, 20% by weight, 21% by weight, 22% by weight, 23% by weight, 24% by weight, 25% by weight, 26% by weight, 27% by weight, 28% by weight, 29% by weight, 30% by weight, 31% by weight, 32% by weight, 33% by weight, 34% by weight, 35% by weight, 36% by weight, 37% by weight, 38% by weight, 39% by weight, 40% by weight, 41% by weight, 42% by weight, 43% by weight, 44% by weight, 45% by weight, 46% by weight, 47% by weight, 48% by weight, 49% by weight, 50% by weight, 51% by weight, 52% by weight, 53% by weight, 54% by weight, 55% by weight, 56% by weight, 57% by weight, 58% by weight, 59% by weight, 60% by weight, 61% by weight, 62% by weight, 63% by weight, 64% by weight %, 27% by weight, 28% by weight, 29% by weight, 30% by weight, 31% by weight, 32% by weight, 33% by weight, 34% by weight, 35% by weight, 36% by weight, 37% by weight, 38% by weight, 39% by weight, 40% by weight, 41% by weight, 42% by weight, 43% by weight, 44% by weight, 45% by weight, 46% by weight, 47% by weight, 48% by weight, 49% by weight, 50% by weight, specifically 10% to 40% by weight, more specifically 15% to 30% by weight. In this range, the peel strength and durability reliability of the adhesive film may be further improved.

[0078] The monomer mixture may further include a copolymerizable monomer in addition to the monomer having a homopolymer glass transition temperature of about -50°C or less and the (meth)acrylate having a hydroxyl group. The copolymerizable monomer may be further included in the monomer mixture to provide an additional effect to the PSA film. The copolymerizable monomer is a monomer different from the above-mentioned monomers, and may 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.

[0079] 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, acryloxyethyl trimethylammonium chloride acrylate, but is not limited thereto.

[0080] 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, and 3-butoxyhexyl acrylate.

[0081] The monomer having a phosphoric acid group may be an acrylic monomer having a phosphoric acid group, such as 2-methacryloyloxyethyl diphenyl phosphate acrylate, trimethacryloyloxyethyl phosphate acrylate, or triacryloyloxyethyl phosphate acrylate, but is not limited thereto.

[0082] 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, sodium 2-acrylamido-2-methylpropanesulfonate, etc., but is not limited thereto.

[0083] 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.

[0084] The monomer having a silane group may be a vinyl monomer having a silane group, such as, but not limited to, 2-acetoacetoxyethyl acrylate, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethyl)silane, vinyltriacetoxysilane, acryloyloxypropyltrimethoxysilane, etc.

[0085] The monomer having a carboxylic acid group may 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.

[0086] 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, and the like.

[0087] The copolymerizable monomer may be included in the monomer mixture in an amount of 30% by weight or less, preferably 0% to 30% by weight, in which the adhesive strength with the adhesive and optical properties can be adjusted.

[0088] The epoxy-based silane coupling agent can reduce the rate of change in the shear deformation rate of the adhesive film before and after it is left at high temperature and high humidity for a long period of time to a similar value that does not change significantly compared to the initial shear deformation rate, thereby making it possible to reduce the rate of change in the shear deformation rate of the adhesive film before and after it is left at high temperature and high humidity for a long period of time to 10% or less, as calculated by Equation 1.

[0089] As a result, the adhesive film can maintain its folding properties at low temperatures and high temperatures even after being left at high temperature and high humidity for a long period of time, and the rate of change in peel strength is reduced even after being left at high temperature and high humidity for a long period of time, allowing the adhesive film to exhibit excellent waterproofing properties.

[0090] In one specific example, the adhesive film may have a rate of change in shear deformation rate of about 10% or less as shown in formula 1. The inventors have confirmed that the above-mentioned effects of the present invention can be obtained by adding an epoxy-based silane coupling agent to the above-mentioned monomer mixture. They have confirmed that the above-mentioned effects of the present invention cannot be obtained when an amino-based silane coupling agent, an acrylic-based silane coupling agent, a (meth)acrylic-based silane coupling agent, a mercapto-based silane coupling agent, a vinyl-based silane coupling agent, or an isocyanate-based silane coupling agent is used in addition to the epoxy-based silane coupling agent.

[0091] In one embodiment, the adhesive film has a peel strength change rate of about 50% or less, for example, 0%, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 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%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 100%, 102%, 104%, 106%, 108%, 109%, 110%, 111%, %, 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%, for example, 0.1% to 20%, 0.5% to 10%, or more specifically, 1% to 5%. In the above range, the adhesive film has a low rate of change in peel strength due to long-term storage under high temperature and high humidity, so that the foldability can be easily maintained even after storage under high temperature and high humidity.

[0092]

number

[0093] (In the above formula 2, C is the initial peel strength (unit: gf / 25 mm) of the adhesive film to the glass plate in a test piece in which a glass plate, an adhesive film, and a corona-treated polyethylene terephthalate film are laminated in this order, D is the peel strength (unit: gf / 25 mm) of the pressure-sensitive adhesive film to the glass plate after leaving the test piece at 60°C and 95% relative humidity for 10 days and then at 25°C for 2 hours.

[0094] In the formula 2, D may be about 400gf / 25mm or more, for example, 400gf / 25mm, 450gf / 25mm, 500gf / 25mm, 550gf / 25mm, 600gf / 25mm, 650gf / 25mm, 700gf / 25mm, 750gf / 25mm, 800gf / 25mm, for example, 400gf / 25mm to 800gf / 25mm. In this range, the rate of change of the peel strength in the formula 2 can be easily reached.

[0095] In one embodiment, the adhesive film may have a modulus of about 0.3 MPa or less, e.g., 0.01 MPa, 0.05 MPa, 0.1 MPa, 0.15 MPa, 0.2 MPa, 0.25 MPa, 0.3 MPa, e.g., 0.01 MPa to 0.3 MPa, 0.05 MPa to 0.15 MPa, at -20°C after being left at 60°C and 95% relative humidity for 10 days. In this range, the adhesive film has little change compared to the initial modulus at -20°C even after being left at high temperature and high humidity, so that the adhesive film can ensure viscoelasticity at low temperatures, and as a result, the adhesive film can have excellent folding properties at low temperatures.

[0096] In one embodiment, the adhesive film may have a modulus of about 0.04 MPa or less, for example, 0.01 MPa, 0.015 MPa, 0.02 MPa, 0.025 MPa, 0.03 MPa, 0.035 MPa, 0.04 MPa, for example, 0.01 MPa to 0.035 MPa, at 60°C after being left at 60°C and 95% relative humidity for 10 days. In this range, the adhesive film has little change compared to the initial modulus at -60°C even after being left at high temperature and high humidity, so that the adhesive film can ensure viscoelasticity at high temperatures, which can help the adhesive film to have excellent folding properties at high temperatures.

[0097] In one embodiment, the adhesive film may have a rate of change in modulus of about 10% or less, for example, 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, for example, 0% to 10%, as shown in the following formula 3. In this range, the rate of change in high-temperature modulus of the adhesive film when left for a long period of time under high temperature and high humidity is low, so that the adhesive film has good folding properties even when repeatedly folded from low temperature to high temperature.

[0098]

number

[0099] (In the above formula 3, E is the initial modulus of the adhesive film at 60 ° C. (unit: MPa), F is the modulus (unit: MPa) at 60°C of the adhesive film after leaving an adhesive sheet, which is an adhesive film and a release polyethylene terephthalate film laminated on both sides of the adhesive film, at 60°C and 95% relative humidity for 10 days and then at 25°C for 2 hours.

[0100] The release polyethylene terephthalate film may be a film having a thickness of 30 μm to 100 μm, the surface of which that contacts the adhesive film is subjected to release treatment (for example, silicon treatment or fluorine treatment).

[0101] The "epoxy-based silane coupling agent" refers to a silane coupling agent having one or more epoxy groups as an alkoxysilane monomer or alkoxysilane oligomer. The "epoxy group" may refer to an epoxycyclohexyl group including a 3,4-epoxycyclohexyl group, a glycidoxyalkyl group including a 3-glycidoxypropyl group, etc. For example, the epoxy-based silane coupling agent may include one or more of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane.

[0102] The epoxy-based silane coupling agent may be included in an amount of about 0.2 parts by weight or more relative to 100 parts by weight of the monomer mixture. In this range, the adhesive film may reach the rate of change of the formula 1 after being left at high temperature and high humidity for a long period of time. Preferably, the epoxy-based silane coupling agent may be included in an amount of 0.2 to 5 parts by weight relative to 100 parts by weight of the monomer mixture, for example, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1 parts by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, for example, 0.2 parts by weight to 1 part by weight, more specifically, 0.2 parts by weight to 0.6 parts by weight.

[0103] The composition may further include an initiator, which may form an adhesive film by curing the composition or may form a partial polymer of the monomer mixture by polymerizing the monomer mixture in the composition.

[0104] The initiator may include at least one of a photopolymerization initiator and a thermal polymerization initiator.

[0105] As the photopolymerization initiator, any can be used as long as it can induce a polymerization reaction of a radical polymerizable compound in the curing process by light irradiation, etc. For example, as the photopolymerization initiator, a benzoin-based, hydroxyketone-based, aminoketone-based, or phosphine oxide-based photoinitiator can be used, and specifically, 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-phenylacetophenone, 2,2'-dimethoxy ... Acetophenone compounds such as methylpropiophenone, pt-butyltrichloroacetophenone, pt-butyldichloroacetophenone, 4-chloroacetophenone, and 2,2'-dichloro-4-phenoxyacetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenone), (2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzophenone, p-phenylbenzophenone, 4,4 diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, 2-aminoanthraquinone, Examples of such 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.

[0106] As the thermal polymerization initiator, for example, a typical initiator such as an azo compound, a peroxide compound, or a redox compound can be used.Examples of the azo-based compound include 2,2-azobis(2-methylbutyronitrile), 2,2-tolylazobis(isobutyronitrile), 2,2-tolylazobis(2,4-dimethylvaleronitrile), 2,2-nitrazobis-2-hydroxymethylpropionitrile, dimethyl-2,2-methylazobis(2-methylpropionate), and 2,2-ioazobis(4-methoxy-2,4-dimethylvaleronitrile). Examples of the peroxide-based compound include inorganic peroxides such as potassium perlactate, ammonium persulfate, and hydrogen peroxide; are diacyl peroxy, peroxydicarbonates, peroxyesters, tetramethylbutyl peroxyneodecanoate, bis(4-butylcyclohexyl) peroxydicarbonate, di(2-ethylhexyl) peroxycarbonate, butyl peroxyneodecanoate, dipropyl peroxydicarbonate, diisopropyl peroxydicarbonate, diethoxyethyl peroxydicarbonate, diethoxyhexyl peroxydicarbonate, hexyl peroxydicarbonate, dimethoxybutyl peroxydicarbonate, bis (3-Methoxy-3-methoxybutyl) peroxydicarbonate, dibutyl peroxydicarbonate, dicetyl peroxydicarbonate, dimyristyl peroxydicarbonate, 1,1,3,3-tetramethylbutyl peroxypivalate, hexyl peroxypivalate, butyl peroxypivalate, trimethylhexanoyl peroxide, dimethylhydroxybutyl peroxyneodecanoate, amyl peroxyneodecanoate, butyl peroxyne Examples of the organic peroxides include odecanoate, t-butyl peroxyneoheptanoate, amyl peroxypivalate, t-butyl peroxypivalate, t-amyl peroxy-2-ethylhexanoate, lauryl peroxide, dilauroyl peroxide, didecanoyl peroxide, benzoyl peroxide, and dibenzoyl peroxide. Examples of the redox compound include, but are not limited to, a mixture of a peroxide compound and a reducing agent.

[0107] The initiator may be included in an amount of about 0.0001 to about 5 parts by weight, specifically 0.001 to 3 parts by weight, more specifically 0.001 to 1 part by weight, based on 100 parts by weight of the monomer mixture. In this range, the curing reaction can be completed, the light transmittance of the adhesive film can be prevented from decreasing due to the remaining amount of the initiator, and the generation of bubbles can be reduced, resulting in excellent reactivity.

[0108] The composition may further include a crosslinking agent, which can increase the degree of crosslinking of the composition and increase the mechanical strength of the PSA film.

[0109] The crosslinking agent can include a multifunctional (meth)acrylate that can be cured with active energy 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, arylated di(meth)acrylate, di(meth)acryloxyethyl isocyanurate ... Cyclohexyl 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. functional acrylates; trifunctional acrylates such as trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide modified trimethylolpropane tri(meth)acrylate, trifunctional urethane (meth)acrylate, 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 erythritol 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).

[0110] The crosslinking agent may be included in an amount of about 0.001 parts by weight to about 5 parts by weight, for example, 0.001 parts by weight, 0.05 parts by weight, 0.1 parts by weight, 0.15 parts by weight, 0.2 parts by weight, 0.25 parts by weight, 0.3 parts by weight, 0.35 parts by weight, 0.4 parts by weight, 0.45 parts by weight, 0.5 parts by weight, 0.55 parts by weight, 0.6 parts by weight, 0.65 parts by weight, 0.7 parts by weight, 0.75 parts by weight, 0.8 parts by weight, 0.85 parts by weight, 0.9 parts by weight, 0.95 parts by weight, 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, specifically, 0.003 parts by weight to 3 parts by weight, specifically, 0.005 parts by weight to 1 part by weight, based on 100 parts by weight of the monomer mixture. In the above range, there is an effect of excellent peel strength and increased reliability.

[0111] The composition may further include an additive. The additive may be included in the composition for the PSA film and may include a typical additive known to those skilled in the art. For example, the additive may include one or more of a pigment, an ultraviolet absorber, a leveling agent, and an antistatic agent, but is not limited thereto.

[0112] The adhesive film may have a glass transition temperature (Tg) of about -100°C to about -10°C, for example, -100°C, -95°C, -90°C, -85°C, -80°C, -75°C, -70°C, -65°C, -60°C, -55°C, -50°C, -45°C, -40°C, -35°C, specifically -70°C to -35°C. In this range, the folding reliability at low and high temperatures may be improved. Preferably, the adhesive film may have a glass transition temperature of -70°C to -45°C. In this range, the folding reliability at low and high temperatures may be improved, and the folding property may be excellent because the stress can be relieved even when folding in the tensile direction.

[0113] The adhesive film may have a haze of about 2% or less, specifically 0.1% to 1%, and a total light transmittance of about 90% or more, specifically 95% to 99%, in the visible light region (e.g., wavelength 380 nm to 780 nm). In this range, the optical transparency is improved, so the adhesive film can be used in optical display devices.

[0114] The thickness of the adhesive film may be about 10 μm to about 300 μm, specifically 12 μm to 175 μm, in which case the adhesive film may be used in optical display devices.

[0115] The pressure sensitive adhesive film can be produced by partially polymerizing the monomer mixture with an initiator, adding an epoxy silane coupling agent to produce a composition, coating the composition on a release film, and curing, for example, by photocuring. The curing is carried out in an oxygen-free environment using a low pressure lamp at a wavelength of 300 nm to 400 nm with an irradiation dose of 400 mJ / cm. 2 ~3000mJ / cm 2 The composition may include irradiation with light of 1000 nm. When the composition is prepared, an initiator, a crosslinking agent, an additive, etc. may be further included. The partial polymerization may include solution polymerization, suspension polymerization, photopolymerization, bulk polymerization, or emulsion polymerization. Specifically, the solution polymerization may be carried out at 50°C to 100°C by adding an initiator to the monomer mixture. As the initiator, an acetophenone-based initiator including 2,2-dimethoxy-2-phenylacetophenone, etc., and a photopolymerization initiator such as 1-hydroxycyclohexyl phenyl ketone may be used. The partial polymerization may have a viscosity of 300 cPs to 50,000 cPs, specifically 500 cPs to 9,000 cPs at 25°C.

[0116] Hereinafter, a pressure-sensitive adhesive film according to another embodiment of the present invention will be described.

[0117] The adhesive film is formed from a composition including a monomer mixture including a monomer having a homopolymer glass transition temperature of about -50°C or less and a (meth)acrylate having a hydroxyl group, an epoxy-based silane coupling agent, and organic nanoparticles, and the adhesive film has a rate of change in shear deformation rate of about 10% or less as shown in Equation 1. The adhesive film is substantially the same as the adhesive film of one embodiment of the present invention, except that it further includes organic nanoparticles.

[0118] The organic nanoparticles can further increase the modulus of the adhesive film at high temperatures compared to a film not containing organic nanoparticles, prevent peeling and / or lifting and / or the generation of bubbles in the adhesive film at high temperatures, and further increase the reliability at high temperatures. The organic nanoparticles have a high glass transition temperature, so they can increase the modulus of the adhesive film at high temperatures.

[0119] The organic nanoparticles may be included in an amount of about 0.1 parts by weight to about 20 parts by weight, for example, 0.1 parts by weight, 0.5 parts by weight, 1 parts by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, 20 parts by weight, specifically, 0.5 parts by weight to 12 parts by weight, specifically, 0.5 parts by weight to 8 parts by weight, based on 100 parts by weight of the monomer mixture. In this range, the modulus of the adhesive film at high temperature may be increased, the folding property of the adhesive film at room temperature and high temperature may be improved, and the viscoelasticity of the adhesive film at low temperature and / or room temperature may be excellent.

[0120] The average particle size of the organic nanoparticles may be about 10 nm to about 400 nm, specifically 10 nm to 300 nm, more specifically 30 nm to 280 nm, and more specifically 50 nm to 280 nm. In this range, the total light transmittance in the visible light region is 90% or more without affecting the folding of the adhesive film, and the transparency of the adhesive film may be good.

[0121] The difference in refractive index between the organic nanoparticles and the partial (meth)acrylic polymer or (meth)acrylic polymer formed from the monomer mixture may be about 0.1 or less, for example, 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, specifically 0 to 0.05, specifically 0 to 0.02. In this range, the transparency of the adhesive film may be excellent. The refractive index of the organic nanoparticles may be about 1.35 to about 1.70, specifically 1.40 to 1.60. In this range, the transparency of the adhesive film may be excellent.

[0122] The organic nanoparticles may include, but are not limited to, simple nanoparticles such as core-shell type and bead type. In the case of the core-shell type, the core and shell may satisfy the following formula 4. That is, both the core and the shell may be nanoparticles made of organic materials. When the particle has the above particle morphology, the adhesive film may have good folding properties and may be effective in balancing the physical properties of elasticity and flexibility.

[0123]

number

[0124] (In the above formula 4, Tg(c) is the glass transition temperature of the core (unit: ° C.), Tg(s) is the glass transition temperature of the shell (unit: °C).

[0125] In this specification, "shell" refers to the outermost layer of an organic nanoparticle. The core may be a single spherical particle. However, the core may further include an additional layer covering the spherical particle as long as the core has the above glass transition temperature.

[0126] Specifically, the glass transition temperature of the core may be about -150°C to about 10°C, for example, -150°C, -140°C, -130°C, -120°C, -110°C, -100°C, -90°C, -80°C, -70°C, -60°C, -50°C, -40°C, -30°C, -20°C, -10°C, 0°C, 10°C, specifically -150°C to -5°C, more specifically -150°C to -20°C. In this range, the adhesive film may have a viscoelastic effect at low temperature and / or room temperature. The core may include one or more of polyalkyl acrylate, polysiloxane, and polybutadiene having the above glass transition temperature.

[0127] 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, polyethylhexyl methacrylate, and polysiloxane.

[0128] The polysiloxane may be, for example, an organosiloxane (co)polymer. As the organosiloxane (co)polymer, a non-crosslinked one or a crosslinked (co)polymer may be used. For impact resistance and colorability, a crosslinked organosiloxane (co)polymer may be used. This is a crosslinked form of organosiloxane, and specifically, it may include crosslinked dimethylsiloxane, methylphenylsiloxane, diphenylsiloxane, or a mixture of two or more thereof. By using a form in which two or more organosiloxanes are copolymerized, the refractive index can be adjusted to 1.41 to 1.50.

[0129] The crosslinked state of the organosiloxane (co)polymer can be judged based on the degree of dissolution in various organic solvents. The deeper the crosslinked state, the smaller the degree of dissolution in the solvent. Acetone, toluene, etc. can be used as a solvent for judging the crosslinked state, and specifically, the organosiloxane (co)polymer can have a portion that is not dissolved in acetone or toluene. The organosiloxane copolymer may have 30% or more of insoluble components in toluene.

[0130] Additionally, the organosiloxane (co)polymer may further include an alkyl acrylate crosslinked polymer. As the alkyl acrylate crosslinked polymer, methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, etc. may be used. For example, n-butyl acrylate or 2-ethylhexyl acrylate having a low glass transition temperature may be used.

[0131] Specifically, the glass transition temperature of the shell may be about 15°C to about 150°C, for example, 15°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, specifically 35°C to 150°C, more specifically 50°C to 140°C. In 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.

[0132] The core may be contained in the organic nanoparticles at about 30% by weight to about 99% by weight, specifically 40% by weight to 95% by weight, and more specifically 50% by weight to 90% by weight. In this range, the folding property of the adhesive film may be good in a wide temperature range. The shell may be contained in the organic nanoparticles at about 1% by weight to about 70% by weight, specifically 5% by weight to 60% by weight, and more specifically 10% by weight to 50% by weight. In this range, the folding property of the adhesive film may be good in a wide temperature range.

[0133] The organic nanoparticles may be contained in the adhesive film in an amount of about 0.1% to about 20% by weight, for example, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20% by weight, specifically 0.5% to 12% by weight, specifically 0.5% to 8% by weight. In this range, the modulus of the adhesive film at high temperatures may be increased, the folding property of the adhesive film at room temperature and high temperature may be improved, and the viscoelasticity of the adhesive film at low temperature and / or room temperature may be excellent.

[0134] The organic nanoparticles can be prepared by conventional emulsion, suspension, and solution polymerization methods.

[0135] The 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, the adhesive film including the adhesive film according to each embodiment of the present invention, and thus the optical member has good bending and / or folding properties and can be used in a flexible display device.

[0136] 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 electrical conductivity, and examples of the optical film include window films, windows, polarizing plates, color filters, retardation films, elliptical polarizing films, reflective polarizing films, anti-reflection films, compensation films, brightness enhancement films, alignment films, light diffusion films, glass shatterproof films, surface protection films, OLED device barrier layers, plastic LCD substrates, transparent electrode films including ITO (indium tin oxide), FTO (fluorinated tin oxide), AZO (aluminum doped zinc oxide), CNT (carbon nanotube), Ag nanowires, graphene, etc. The optical film can be easily manufactured by a person having ordinary skill in the art to which the present invention pertains.

[0137] For example, a touch panel can be formed by attaching a window or optical film to a touch pad using an adhesive film, or an adhesive film can be applied to a normal polarizing film as in the past.

[0138] 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 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 may be a film having a total light transmittance of 90% or more in the visible light region and formed of one or more resins selected from 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 thickness of the optical film may be 10 μm to 100 μm, specifically 20 μm to 75 μm, and more specifically 30 μm to 50 μm. In the above range, the optical film can be used as a support layer of a display element.

[0139] The optical member may be a two-layer optical member including an optical film and an adhesive film formed on one side of the optical film, or may be a three-layer or more film laminate including two or more optical films, at least two of which are laminated with the adhesive film of the present invention.

[0140] In one embodiment, the optical member may be a three-layer film laminate including a first optical film, a second optical film, and the first optical film and the second optical film laminated with the adhesive film of the present invention. The first optical film and the second optical film may be films formed of one or more resins selected from the group consisting of polyethylene terephthalate resin, polycarbonate resin, polyimide resin, polyacrylate resin, cyclic olefin polymer resin, and acrylic resin. The first optical film and the second optical film may each have a thickness of 10 μm to 100 μm, specifically 20 μm to 75 μm, and more specifically 30 μm to 50 μm, and the adhesive film may have a thickness of 10 μm to 100 μm. In this range, there may be an effect of maximizing impact resistance while maintaining good folding properties. The first optical film and the second optical film may each have the same thickness and material or different materials.

[0141] The optical display device of the present invention includes the pressure-sensitive adhesive film of the present invention.

[0142] The optical display device may include an organic light emitting diode display device, a liquid crystal display device, etc. The optical display device may include a flexible display device, but may also include a non-flexible display device.

[0143] [Mode for carrying out the invention] Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention, however, these are presented as preferred examples of the present invention and should not be construed as limiting the present invention in any sense.

[0144] Manufacturing example: Manufacturing of organic nanoparticles Organic nanoparticles were produced by emulsion polymerization. The core was made of polybutyl acrylate and the shell was made of polymethyl methacrylate, with the shell being 35% by weight of the organic nanoparticles and the core being 65% by weight of the organic nanoparticles. The average particle size was 100 nm and the refractive index was 1.48.

[0145] Example 1 As shown in Table 1 below, 100 parts by weight of the monomer mixture, 100 ppm of the initiator Irgacure 651, and 3 parts by weight of the organic nanoparticles prepared in the above Preparation Example were thoroughly mixed in a reactor. The dissolved oxygen in the reactor was replaced with nitrogen gas for 30 minutes, and the monomer mixture was partially polymerized by irradiating ultraviolet light using a low-pressure mercury lamp for several minutes to produce a viscous liquid having a viscosity of 40 cps to 50 cps at 25°C. Thereafter, the low-pressure mercury lamp was turned off, and the polymerization reaction was terminated by cooling the reactor with air for 30 minutes, thereby obtaining a (meth)acrylic prepolymer prepared from the monomer mixture. The reactor contained the (meth)acrylic prepolymer prepared from the monomer mixture, unreacted monomers, and organic nanoparticles.

[0146] Then, a mixture of 0.2 parts by weight of Omnirad 127 and 0.1 parts by weight of Omnirad 651 was mixed as an initiator with 0.035 parts by weight of dipentaerythritol hexaacrylate (DPHA) and 0.2 parts by weight of an epoxy silane coupling agent, KBM-403 (3-glycidoxypropyltrimethoxysilane, Shin-Etsu Chemical Co., Ltd.), to produce a composition for adhesive films.

[0147] The adhesive film composition prepared above was coated on one side of a release PET film to a predetermined thickness using a blade, and then the release PET film was placed on top of the film. The film was then exposed to ultraviolet light at a wavelength of 1200 mJ / cm using a low-pressure mercury lamp. 2 After the first hardening, the resin was irradiated with 2000mJ / cm using a metal halide lamp. 2 The adhesive sheet was then subjected to secondary curing by irradiation with light at 400 V for 1 hour, producing an adhesive sheet which was a laminate of PET release film-adhesive film-PET release film.

[0148] Examples 2 to 5 An adhesive sheet was produced in the same manner as in Example 1, except that the composition for an adhesive film was changed as shown in Table 1 below.

[0149] Comparative Examples 1 to 4 An adhesive sheet was produced in the same manner as in Example 1, except that the composition for an adhesive film was changed as shown in Table 1 below.

[0150] The PET release film was peeled off from the pressure-sensitive adhesive sheets produced in the Examples and Comparative Examples to produce pressure-sensitive adhesive films. The physical properties of the pressure-sensitive adhesive films were evaluated in Table 1 below, and the results are shown in Table 1 below.

[0151] (1) Peel strength (unit: gf / 25mm): A sample adhesive sheet (length x width: 25mm x 25mm) was obtained from the adhesive sheets of the examples and comparative examples. One side of a PET film (length x width x thickness: 150mm x 25mm x 75μm) was corona-treated by two corona treatments (total dose: 156 doses) while discharging with a dose of 78 doses (unit: W / (m / minm)) per treatment using a corona treatment machine. The PET release film on one side of the sample adhesive sheet was removed from the corona-treated surface of the corona-treated PET film, one side of the adhesive film was placed on the corona-treated surface of the corona-treated PET film, the PET release film on the other side of the adhesive sheet was removed, and the other side of the adhesive film was placed on a glass plate (soda-lime glass) and pressed with a 2kg hand roller to produce a test specimen.

[0152] The prepared test piece was fixed to a peel strength measuring device, TA.XT-Plus Texture Analyzer (manufactured by Stable Micro System). Using the TA.XT-Plus Texture Analyzer, the adhesive film and the PET film were pulled at 180° from the glass plate at 25°C at a speed of 300 mm / min, and the peel strength was measured when the adhesive film and the PET film started to peel off from the glass plate, and this value was taken as the "initial peel strength".

[0153] Adhesive sheets with length x width (25 mm x 25 mm) were obtained from the adhesive sheets of the examples and comparative examples. Test pieces were prepared as described above, and the test pieces were left in a chamber at 60°C and 95% relative humidity for 10 days, then removed and placed at 25°C for 2 hours, after which the peel strength was measured in the same manner as in the initial peel strength measurement, and this value was taken as the "peel strength after high temperature and high humidity."

[0154] (2) Modulus (unit: MPa): A sample with a thickness of 500 μm was prepared by laminating a plurality of the adhesive films prepared in the examples and comparative examples. The laminate of the adhesive film sample was punched using a punch with a diameter of 8 mm, and the resultant was used as a test piece. The modulus was measured under the conditions of 1% strain and 1 Hz in a temperature sweep test mode with a temperature rise rate of 5°C / min in the temperature range of -50°C to 100°C using a Rheometer (TA, DHR3), which is a dynamic viscoelasticity measuring device. The modulus was obtained at -20°C and 60°C, and this value was designated as the "initial modulus".

[0155] The adhesive sheets (with release PET films laminated on both sides of the adhesive film) produced in the examples and comparative examples were left in a chamber at 60° C. and 95% relative humidity for 10 days, then removed and left at 25° C. for 2 hours. Thereafter, the adhesive films were obtained, and the modulus was measured in the same manner as in the initial modulus measurement, and this value was taken as the "modulus after high temperature and high humidity."

[0156] (3) Shear deformation rate (unit: %): The PET films on both sides of the adhesive sheets of the examples and comparative examples were released to obtain adhesive films (length x width: 100 mm x 25 mm). A plurality of adhesive films were laminated, and the laminate was perforated using a punching machine with a diameter of 8 mm to produce cylindrical test pieces (thickness: 400 μm, diameter: 8 mm) having upper and lower surfaces.

[0157] The upper and lower surfaces of the manufactured cylindrical test piece were attached so that they engaged with the upper and lower jigs of a rheometer (TA, DHR3), a dynamic viscoelasticity measuring device. The chamber temperature was set to 60°C, the axial force to 1N, and the torque to 2000Pa. The time was specified as 600 seconds, and the deformation rate value at 600 seconds was taken as the shear deformation rate, and this value was defined as the "initial shear deformation rate."

[0158] The adhesive sheets (adhesive film with release PET film laminated on both sides) manufactured in the examples and comparative examples were left in a chamber at 60°C and 95% relative humidity for 10 days, then removed and placed at 25°C for 2 hours. After that, the adhesive film was obtained, and the shear deformation rate was measured in the same manner as the initial shear deformation rate measurement, and this value was defined as the "shear deformation rate after high temperature and high humidity". The rate of change was calculated using Equation 1.

[0159] (4)Flexibility 1(@-20℃): A module specimen was fabricated by laminating a window film, an adhesive film, a polarizer, an adhesive film, and an OLED panel in this order. The following window film, adhesive film, polarizer, adhesive film, and OLED panel were used in fabricating the module.

[0160] - Window film: replaced with PET film (thickness: 100 μm, Cosmoshine TA015, Toyobo Co., Ltd.).

[0161] -Adhesive film: The adhesive films prepared in the examples and comparative examples were used.

[0162] -Polarizer: PVA resin dyed with iodine was used. A 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 MD stretched 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 hue, and then dried at 50℃ for 4 minutes to produce a polarizer (thickness 25μm).

[0163] -OLED panel: Replaced with PET film (thickness: 100 μm, Cosmoshine TA015, Toyobo Co., Ltd.).

[0164] The manufactured module specimen was cut into a size of 170mm x 110mm in length x width, and left in a chamber at 60°C and 95% relative humidity for 10 days, and then folded 100,000 times at -20°C to evaluate whether bubbles, cracks, and delamination occurred in the module specimen. The module specimen was folded in the length direction and in the OLED panel direction, with a curvature radius of 1.5mm, and the folding rate was 30 cycles per minute. One cycle means that the specimen is folded at the curvature radius and expanded to 180°. If no bubbles, cracks, or delamination occurred, it was evaluated as "OK", and if one or more of bubbles, cracks, and delamination occurred, it was evaluated as "NG".

[0165] (5) Flexural reliability 2 (@60°C): Module test pieces were prepared in the same manner as in (4). After leaving them in a chamber at 60°C and 95% relative humidity for 10 days, the flexural reliability was evaluated at 60°C in the same manner as in (4).

[0166] [Table 1]

[0167] *Monomer 1: 2-Ethylhexyl acrylate (branched chain type, homopolymer Tg: -70℃) *Monomer 2: 4-hydroxybutyl acrylate (Tg of homopolymer: -40℃) *Monomer 3: 2-Ethylhexyl diethylene glycol acrylate (Tg of homopolymer: -72℃) *Omnirad 127 (IGM Resins BV) *Omnirad 651 (IGM Resins BV) *DPHA: Dipentaerythritol hexaacrylate *SC1: Epoxy-based silane coupling agent, 3-glycidoxypropyltrimethoxysilane (KBM-403, Shin-Etsu Chemical Co., Ltd.) *SC2: Methacrylic silane coupling agent, 3-methacryloxypropyltriethoxysilane (KBE-503, Shin-Etsu Chemical Co., Ltd.) *SC3: Acrylic silane coupling agent, 3-acryloxypropyltrimethoxysilane (KBM-5103, Shin-Etsu Chemical Co., Ltd.) *SC4: Amino-silane coupling agent, 3-aminopropyltriethoxysilane (KBE-903, Shin-Etsu Chemical Co., Ltd.) As shown in Table 1, the pressure-sensitive adhesive film of the present invention can have excellent waterproofing because the change in rheological properties is less than that before being left at high temperature and high humidity for a long period of time when the value of formula 1 is 10% or less. In addition, the values ​​of formula 2 and formula 3 each satisfy the range of the present application, so that the foldability at low temperature and high temperature can be excellent.

[0168] On the other hand, the comparative examples that do not satisfy the present invention do not have folding properties at low temperatures and high temperatures, and in the case of formula 1, the folding properties significantly exceed 10%. Even after being left at high temperature and high humidity for a long period of time, the change in rheological properties is large compared to before being left at high temperature and high humidity for a long period of time, and the waterproofness is low, so they cannot be used for foldable displays that require waterproofing.

[0169] Simple modifications and variations of the present invention can be easily implemented by those having ordinary skill in the art, and all such modifications and variations can be considered to be included within the scope of the present invention.

Claims

1. A pressure-sensitive adhesive film obtained by curing a composition containing a monomer mixture including a monomer having a homopolymer glass transition temperature of −50° C. or lower and a (meth)acrylate having a hydroxyl group, and an epoxy-based silane coupling agent, The monomer having a homopolymer glass transition temperature of −50° C. or less includes a mixture of a (meth)acrylic acid ester having an unsubstituted alkyl group having 3 to 20 carbon atoms and no alkylene glycol group, and a (meth)acrylic acid ester having an unsubstituted alkyl group having 3 to 20 carbon atoms and an alkylene glycol group, The pressure-sensitive adhesive film has a rate of change in shear deformation rate as determined by the following formula 1 of 10% or less. [0010] (In the above formula 1, A is the initial shear deformation rate (unit: %) of the PSA film, B is the shear deformation rate value (unit: %) of the adhesive film obtained from the adhesive sheet obtained by leaving the adhesive film and the adhesive sheet having release polyethylene terephthalate films laminated on both sides of the adhesive film at 60°C and 95% relative humidity for 10 days and then leaving it at 25°C for 2 hours.

2. The pressure-sensitive adhesive film according to claim 1 , wherein in formula 1, A is 10% or more and B is 10% or more.

3. The pressure-sensitive adhesive film according to claim 1, wherein the pressure-sensitive adhesive film has an initial modulus of 0.3 MPa or less at -20°C.

4. The pressure-sensitive adhesive film according to claim 1 , wherein the pressure-sensitive adhesive film has an initial modulus at 60° C. of 0.05 MPa or less.

5. The pressure-sensitive adhesive film according to claim 1 , wherein the change rate of the peel strength as determined by the following formula 2 is 20% or less. [0025] (In the above formula 2, C is the initial peel strength (unit: gf / 25 mm) measured by the following method, D is the peel strength (unit: gf / 25 mm) of the pressure-sensitive adhesive film to the glass plate after leaving the test piece at 60 ° C and 95% relative humidity for 10 days and then at 25 ° C for 2 hours: [Initial peel strength] One side of the PET film was corona-treated twice (total dose: 156 doses) using a corona treatment machine, discharging at a dose of 78 doses (unit: W / (m / min)m) per treatment, One PET release film of the sample adhesive sheet was removed from the corona-treated surface of the corona-treated PET film, one side of the adhesive film was placed on the corona-treated surface of the corona-treated PET film, the other PET release film of the adhesive sheet was removed, and the other side of the adhesive film was placed on a glass plate (soda-lime glass) and pressed with a 2 kg hand roller to prepare a test piece. The adhesive film and the PET film of the test piece are pulled at 180° from the glass plate in the test piece at a speed of 300 mm / min using a peel strength measuring machine at 25° C., and the peel strength is measured when the adhesive film and the PET film start to peel off from the glass plate.

6. The pressure-sensitive adhesive film according to claim 5 , wherein in formula 2, D is 400 gf / 25 mm or more.

7. The pressure-sensitive adhesive film according to claim 1, wherein the pressure-sensitive adhesive film has a modulus of 0.3 MPa or less at -20°C after being left at 60°C and 95% relative humidity for 10 days.

8. The pressure-sensitive adhesive film according to claim 1, wherein the pressure-sensitive adhesive film has a modulus change rate of 10% or less as determined by the following formula 3: [0030] (In the above formula 3, E is the initial modulus (unit: MPa) of the adhesive film at 60 ° C., F is the modulus (unit: MPa) at 60° C. of the adhesive film after leaving an adhesive sheet having a release polyethylene terephthalate film laminated on both sides of the adhesive film at 60° C. and 95% relative humidity for 10 days and then at 25° C. for 2 hours.

9. The pressure-sensitive adhesive film according to claim 1 , wherein the epoxy-based silane coupling agent is contained in an amount of 0.2 to 5 parts by weight based on 100 parts by weight of the monomer mixture.

10. The epoxy-based silane coupling agent includes one or more of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane. The pressure-sensitive adhesive film according to claim 1.

11. The adhesive film according to claim 1, wherein the monomer having a homopolymer glass transition temperature of −50° C. or lower has a branched chain.

12. The pressure-sensitive adhesive film according to claim 1 , wherein the alkyl group having no alkylene glycol group and the alkyl group having an alkylene glycol group each have a branched chain.

13. The pressure-sensitive adhesive film according to claim 1 , wherein the (meth)acrylic acid ester having an unsubstituted alkyl group having 3 to 20 carbon atoms and no alkylene glycol group is contained in an amount of 50% by weight to 80% by weight of the monomer mixture.

14. The pressure-sensitive adhesive film according to claim 1 , wherein the (meth)acrylic acid ester having an unsubstituted alkyl group having 3 to 20 carbon atoms and an alkylene glycol group is contained in an amount of 10 to 40% by weight of the monomer mixture.

15. The composition further comprises at least one crosslinking agent selected from the group consisting of 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, tris(meth)acryloxyethyl isocyanurate, diglycerin tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, caprolactone modified dipentaerythritol hexa(meth)acrylate, and a reaction product of an isocyanate monomer and trimethylolpropane tri(meth)acrylate. The pressure-sensitive adhesive film according to claim 1.

16. The adhesive film according to claim 1 , further comprising organic nanoparticles.

17. The pressure-sensitive adhesive film according to claim 16, wherein the organic nanoparticles are contained in an amount of 0.1 to 20 parts by weight based on 100 parts by weight of the monomer mixture.

18. The adhesive film according to claim 16, wherein the organic nanoparticles include core-shell type nanoparticles satisfying the following formula 4: [0045] (In the above formula 4, Tg(c) is the glass transition temperature of the core (unit: ° C.), Tg(s) is the glass transition temperature of the shell (unit: ° C.)

19. An optical member comprising: an optical film; and an adhesive film formed on at least one surface of the optical film, the adhesive film comprising the adhesive film according to any one of claims 1 to 18.

20. An optical display device comprising the optical member of claim 19.

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