KR102063207B1 - Adhesive film, optical member comprising the same and optical display apparatus comprising the same - Google Patents

Abstract

The ratio of tan δ at 25 ° C. of Formula 1 is 1 to 2, and the ratio of tan δ at 0.1 ° to 1.5 at −20 ° C. of Formula 2 is formed from an adhesive composition comprising a monomer mixture comprising a (meth) acrylic acid ester having a hydroxyl group. The present invention provides an adhesive film, an optical member including the same, and an optical display including the same.

Description

Adhesive film, optical member including the same, and optical display including the same {ADHESIVE FILM, OPTICAL MEMBER COMPRISING THE SAME AND OPTICAL DISPLAY APPARATUS COMPRISING THE SAME}

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

The optical display device includes a display device including a window film, a conductive film, an organic light emitting device, and the like. The touch pad has a structure in which a transparent adhesive film (OCA, optical clear adhesive) is laminated between the window film and the conductive film. The touch pad is operated by a signal generated by the change in capacitance due to contact of a window film such as a human hand or a predetermined object. The transparent adhesive film may be laminated between two kinds of window films, conductive films, polarizing plates, and organic light emitting devices.

Recently, a flexible display device having flexibility to be folded and unfolded in an optical display device has been developed. The flexible display device can be folded and unfolded to be manufactured in various forms, and is thin, light and strong against impact.

In the flexible display device, various optical elements included in the device should have flexibility. Since the transparent adhesive film is formed between the window film and the conductive film, the adhesive force of both sides should be excellent. In addition, in order to be used in a flexible display device, the adhesive film should have good folding property at low temperature and high temperature as well as at room temperature. In addition, the flexible display device may be placed in a folded state for a long time, and as a result, wrinkles may occur in the adhesive film, thereby reducing reliability, optical transparency, and durability.

Background art of the present invention is disclosed in Korean Patent Laid-Open No. 2007-0055363.

The problem to be solved by the present invention is to provide a good pressure-sensitive adhesive film at low and room temperature.

Another problem to be solved by the present invention is to provide a pressure-sensitive adhesive film excellent in mechanical properties while having good folding properties as described above.

Another problem to be solved by the present invention is to provide a pressure-sensitive adhesive film having good resilience, good reliability, optical transparency, durability does not occur even after long-term folding.

Another object of the present invention is to provide an adhesive film having excellent reliability at high temperature and / or high humidity.

Another problem to be solved by the present invention is to provide an optically transparent adhesive film.

The pressure-sensitive adhesive film of the present invention is a pressure-sensitive adhesive composition comprising a monomer mixture containing a (meth) acrylic acid ester having a hydroxyl group of 1 to 2, a ratio of tan δ of the following formula 2 to 0.1 to 1.5, and a hydroxyl group. Can be formed:

<Equation 1>

Ratio of tan δ at 25 ° C. = ([tan δ] 100/25 _{° C.} ) / ([tan δ] 1/25 _{° C.} )

(In Formula 1, [tan δ] 1/25 ° C is tan δ, at 1rad / sec and 25 ° _C of the adhesive film,

[tan δ] 100/25 ° C. is tan δ at 100 rad / sec and 25 ° _C. of the adhesive film)

<Equation 2>

Ratio of tan δ at -20 ° C = ([tan δ] _{100 / -20 ° C} ) / ([tan δ] _{1 / -20 ° C} )

(In Formula 2, [tan δ] _{1 / -20 ℃} is tan δ, at 1rad / sec and -20 ℃ of the adhesive film,

[tan δ] _{100 / -20 ° C.} is tan δ at ₁₀₀ rad / sec and −20 ° _C. of the adhesive film).

The optical member of the present invention may include an optical film and the adhesive film formed on at least one surface of the optical film.

The optical display device of the present invention may include the adhesive film.

The present invention provides an adhesive film having good folding properties at low and normal temperatures.

The present invention provides a pressure-sensitive adhesive film excellent in mechanical properties, while having good folding properties as described above.

The present invention has a good restoring force does not cause wrinkles, etc. even after long-term folding to provide a reliable adhesive film.

The present invention provides an adhesive film having excellent reliability at high temperature and / or high humidity.

The present invention provides an optically transparent adhesive film.

1 is a conceptual diagram of a specimen for measuring the resistance change rate.
2 is a cross-sectional view of a specimen for measuring peel strength.
3 is a conceptual diagram of a specimen for measuring the restoring force.
4 is a graph for restoring force calculation.
5 is a cross-sectional view of a flexible display device according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. The drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification.

In the present specification, "upper" and "lower" are defined based on the drawings, and according to a viewpoint, "upper" may be changed to "lower" and "lower" to "upper", and "on" or What is referred to as “on” may include not only the above but also intervening other structures in the middle. On the other hand, what is referred to as "directly on" or "directly on" means that there is no intervening structure in between.

As used herein, "(meth) acryl" may mean acrylic and / or methacryl.

As used herein, "copolymer" may include oligomers, polymers or resins.

Referring to (a) and (b) of FIG. 3, the term "resilience" in the present specification refers to both ends of a PET (polyethylene terephthalate) film (thickness: 75 μm) each having a width x length (50 mm x 20 mm). , The second end portion, by adhering the end portions of each of the two PET films by an adhesive film of width x length (20mm x 20mm) to each other, the first end portion of the PET film / adhesive film / PET film of the second end portion It is adhered in order, and the contact area between the PET film and the pressure-sensitive adhesive film is measured as a specimen having a width x length (20 mm x 20 mm). 3 and 4, at 25 ° C., one jig is fixed and the other jig is 1000% of the length (adhesive film) of the thickness of the adhesive film (initial thickness: X ₀ , unit: μm) at a speed of 300 mm / min. After pulling up to 10 times the initial thickness of, X ₃ , unit: ㎛) and maintained for 10 seconds, then restored to the speed (300mm / min) at the same speed as the pulled pressure-sensitive adhesive film when a 0kPa force is applied to the adhesive film Extended length (X ₂ , unit: μm) is obtained. Referring to FIG. 4, a graph is obtained using the length of the adhesive film as the X axis and the force applied to the adhesive film as the Y axis. The restoring force is calculated according to Equation 5 below.

<Equation 5>

Resilience = (1-(X ₂ ) / (X ₃ )) x 100

The initial thickness of the adhesive film may be 20 μm to 300 μm. Resilience can be measured with the TA.XT_Plus Texture Analyzer (Stable Micro System).

"Folding condition" in the present specification is 12 hours after the adhesive film is placed between the corona treated thickness 50㎛ polyethylene terephthalate (PET) film, the corona treated surface of the PET film contact with the adhesive film and attached with a roller, After aging at room temperature, cut to the length × width (70mm × 140mm) size, and fixing the cut specimen to the flexibility evaluation equipment (CFT-200, Covotech Co., Ltd.) using the adhesive (4965, Tesa Co., Ltd.) Bending at a rate of 30 cycles per minute so that the length of the specimen (140 mm) of the specimen at -20 ° C. or 25 ° C. becomes 3 mm (bending and releasing the adhesive film in half once in one cycle) Repeated) means the folding condition more than 100,000 cycles.

In the present specification, "good folding" refers to a case in which no streaks and the like are generated at the folding site when the folding conditions are applied, and there are no cracks, lifting, peeling, or the like of the adhesive film or no crack in the PET film.

In the present specification, the "average particle diameter" of the organic nanoparticles is a particle diameter of the organic nanoparticles expressed in Z-average values measured in an aqueous or organic solvent with a Maltas Zetasizer nano-ZS device.

In the present specification, 25 ° C represents room temperature, -20 ° C represents low temperature, and 80 ° C represents high temperature.

When the temperature described when referring to "modulus" or "tan δ" or "ratio of tan δ" herein is X ° C, X ° C is not only X ° C but also (X-5) ° C to (X + 5) It may mean ° C.

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

In the adhesive film according to the present embodiment, the ratio of the following formula 1 tan δ may be 1 to 2, and the ratio of the tan δ of the following formula 2 may be 0.1 to 1.5: In the above range, the adhesive film has good folding property at both room temperature and low temperature. Can be used in flexible displays:

<Equation 1>

Ratio of tan δ at 25 ° C. = ([tan δ] 100/25 _{° C.} ) / ([tan δ] 1/25 _{° C.} )

(In Formula 1, [tan δ] 1/25 ° C is tan δ, at 1rad / sec and 25 ° _C of the adhesive film,

[tan δ] 100/25 ° C. is tan δ at 100 rad / sec and 25 ° _C. of the adhesive film)

<Equation 2>

Ratio of tan δ at -20 ° C = ([tan δ] _{100 / -20 ° C} ) / ([tan δ] _{1 / -20 ° C} )

(In Formula 2, [tan δ] _{1 / -20 ℃} is tan δ, at 1rad / sec and -20 ℃ of the adhesive film,

[tan δ] tan δ at ₁₀₀ rad / sec and -20 ° _C. of _{100 / -20 °} C.

The values of Equations 1 and 2 may be an index for evaluating whether the adhesive film exhibits good folding properties at 25 ° C. and −20 ° C., respectively. tan δ can be expressed as the ratio of loss modulus to storage modulus (loss modulus / storage modulus). As in the following experimental examples, the loss modulus and storage modulus in the present invention are measured while fixing the modulus measurement temperature and raising the shear rate from a low value to a high value. Therefore, the tan δ of the pressure-sensitive adhesive film at a low shear rate and the tan δ of the pressure-sensitive adhesive film at a relatively high shear rate have a specific ratio, thereby evaluating the degree of relaxation of the stress during the folding of the pressure-sensitive adhesive film, thereby Can be evaluated. Specifically, the ratio of tan δ of Equation 1 may be 1.1 to 1.8, and the ratio of tan δ of Equation 2 may be 0.2 to 1.4, more specifically 0.3 to 1.2.

The pressure-sensitive adhesive film may have a tan δ of 0.3 to 0.7 and a storage modulus of 100 kPa or less, specifically, 50 kPa to 100 kPa at −20 ° C. at 1 rad / sec. The adhesive film may have a tan δ of 0.1 to 0.75 and a storage modulus of 1000 kPa or less, and specifically 200 kPa to 1000 kPa at −20 ° C. at 100 rad / sec. In the above range, it may exhibit good folding properties at low temperatures, and there may be an effect that deformation does not occur even when an external force is applied. The adhesive film may have a tan δ of 0.2 to 0.3 and a storage modulus of 15 kPa or more and 18 kPa to 35 kPa at 1 rad / sec at 25 ° C. The adhesive film may have a tan δ of 0.3 to 0.5 and a storage modulus of 20 kPa or more and 25 kPa to 70 kPa at 100 rad / sec at 25 ° C. In the above range, it can exhibit good folding properties at room temperature, not only increase the number of cycles of the foldable test, but also have excellent effects of adhesion and reliability.

The adhesive film may have a gel fraction of Formula 3 of 70% or more, specifically 70% to 85%. In the above range, the mechanical properties of the pressure-sensitive adhesive film may be good, and the durability may have an excellent effect of reliability:

<Equation 3>

Gel fraction = (WC-WA) / (WB-WA) × 100

(Equation 3, WA is the weight of the wire mesh,

WB is measured by putting about 1g of adhesive film in the wire mesh so as not to leak,

WC is obtained by putting the pressure-sensitive adhesive film and the wire mesh in a sample bottle, adding 50 cc of ethyl acetate and leaving it for 1 day, taking out the wire mesh and drying it at 100 ° C. for 12 hours. to be).

As such, the adhesive film may have a gel fraction of Formula 3, and may also have mechanical properties. The adhesive film may have a ratio of tan δ of Formulas 1 and 2, and thus may have good folding properties at room temperature and low temperature. In particular, the pressure-sensitive adhesive film has not only good mechanical properties with the gel fraction of Formula 3 but also a ratio of tan δ of Formula 2 to have good folding properties at low temperatures.

The pressure-sensitive adhesive film may be formed of a pressure-sensitive adhesive composition according to an embodiment of the present invention. The pressure-sensitive adhesive composition will be described in more detail below.

The adhesive film may have a storage modulus at 1 rad / sec at 80 ° C. of 15 kPa or more, specifically 15 kPa to 32 kPa, more specifically 18 kPa to 30 kPa. In the above range, durability at high temperatures of the pressure-sensitive adhesive film, reliability (bubble, lifting, etc. does not occur) may be good, there may be an effect excellent in folding properties.

The adhesive film may have a peel strength of 700 gf / inch or more, specifically 800 gf / inch to 2000 gf / inch at 25 ° C. In the above range, the adherend can be attached to the adhesive film stably, increase the reliability, there can be an effect that no separation of the layer when folding.

The adhesive film may have a haze of 3.0% or less, specifically 0.1% to 0.95%, total light transmittance of 90% or more, and specifically 95% to 99% in the visible light region (for example, a wavelength of 380 nm to 780 nm). In the above range, the transparency can be used in the optical display device. The adhesive film may have a thickness of 10 μm to 300 μm, specifically 20 μm to 150 μm. Within this range, it can be used for an optical display device.

The pressure-sensitive adhesive film may have a resistance change rate of 3% or less, specifically 0% to 3%. Within this range, it is possible to prevent an increase in resistance when adhering to an adherend comprising a metal and to prevent corrosion of the adherend:

<Equation 4>

Resistance change rate = (P ² -P ¹ ) / P ¹ x 100

(In Formula 4, P ¹ is the initial resistance (unit: Ω) measured for the specimens with electrodes formed at both ends of the adhesive film, P ² is the specimen after leaving the specimen at 60 ℃ and 95% relative humidity for 250 hours) Resistance in Ω).

The adhesive film may have a glass transition temperature of -100 ° C to -30 ° C, specifically -80 ° C to -35 ° C. Within this range, the viscoelastic properties at low to high temperatures are excellent.

The pressure-sensitive adhesive film may be prepared by coating the pressure-sensitive adhesive composition according to an embodiment of the present invention on a release film to a predetermined thickness, drying and curing. Hereinafter, the pressure-sensitive adhesive composition according to the present embodiment will be described.

The pressure-sensitive adhesive composition may include a monomer mixture and an initiator, and the monomer mixture may form a (meth) acrylic copolymer.

The (meth) acrylic copolymer formed from the monomer mixture may have a refractive index of 1.40 to 1.70, specifically 1.48 to 1.60. Within this range, transparency can be maintained when laminating with other optical films. The (meth) acrylic copolymer formed from the monomer mixture may have a glass transition temperature (Tg) of -150 ° C to -13 ° C, specifically -100 ° C to -20 ° C. In the above range, the adhesive film has a good folding property, there is an effect having excellent adhesion and reliability in a wide temperature range.

In one embodiment, the monomer mixture is a (meth) acrylic acid ester having a hydroxyl group having a glass transition temperature of homopolymer of 0 ° C. or less, specifically −100 ° C. to 0 ° C. (hereinafter referred to as '(meth) acrylic acid having a hydroxyl group'). Ester '), and a (meth) acrylic acid ester having an alkyl group.

The (meth) acrylic acid ester having a hydroxyl group can lower the storage modulus at low and normal temperatures of the pressure-sensitive adhesive film and increase the adhesive force of the pressure-sensitive adhesive film. The (meth) acrylic acid ester having a hydroxyl group may include a (meth) acrylic acid ester having an alkyl group having 4 to 20 carbon atoms having at least one hydroxyl group. Therefore, the pressure-sensitive adhesive film can realize good folding at both room temperature and low temperature. Specifically, the (meth) acrylic acid ester having a hydroxyl group is 4-hydroxybutyl (meth) acrylate (glass transition temperature of homopolymer is -32 ° C), 2-hydroxybutyl (meth) acrylate (glass of homopolymer) Transition temperature is -49 ° C), and 6-hydroxyhexyl (meth) acrylate. The (meth) acrylic acid ester having a hydroxyl group may be included in an amount of 1% to 30% by weight, specifically 10% to 25% by weight, more specifically 15% to 20% by weight of the monomer mixture for the (meth) acrylic copolymer. Can be. In the above range, the folding property at room temperature and low temperature of the pressure-sensitive adhesive film may be good and the adhesive strength may be excellent.

The (meth) acrylic acid ester having an alkyl group may form a matrix of the adhesive film and improve mechanical properties of the adhesive film. The (meth) acrylic acid ester having an alkyl group may include an (meth) acrylic acid ester having an unsubstituted linear or branched alkyl group having 1 to 20 carbon atoms. For example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, iso-butyl (meth) acrylic Latex, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) One or more of acrylate, decyl (meth) acrylate, lauryl (meth) acrylate. Specifically, the (meth) acrylic acid ester having an alkyl group having 4 to 8 carbon atoms may further have an effect of increasing the initial adhesive strength. Specifically, the (meth) acrylic acid ester having a branched alkyl group may further have an effect of increasing initial adhesion. The (meth) acrylic acid ester having an alkyl group may be included in 70% to 99% by weight, specifically 75% to 90% by weight, more specifically 80% to 85% by weight of the monomer mixture for the (meth) acrylic copolymer. Can be. In the above range, the folding property at room temperature and low temperature of the pressure-sensitive adhesive may have a good effect.

In one embodiment, the monomer mixture comprises from 10% to 25% by weight of (meth) acrylic acid esters having hydroxyl groups and (meth) having alkyl groups in the sum of the (meth) acrylic acid esters having hydroxyl groups and the (meth) acrylic acid esters having alkyl groups. It may comprise 75% to 90% by weight of the acrylic ester, the (meth) acrylic copolymer may be a non-carboxylic acid copolymer. In the above range, the above-described tan δ ratio can be good folding at low temperature and room temperature.

The monomer mixture for the (meth) acrylic copolymer may further include a comonomer polymerizable with at least one of (meth) acrylic acid esters having hydroxyl groups and (meth) acrylic acid esters having alkyl groups. Co-monomers may be included in 0 to 30% by weight of the monomer mixture. The co-monomer may provide additional functions to the pressure-sensitive adhesive film, or may supplement the function of the (meth) acrylic acid ester having a hydroxyl group or the (meth) acrylic acid ester having an alkyl group.

Co-monomers include monomers with ethylene oxide, monomers with propylene oxide, monomers with amine groups, monomers with amide groups, monomers with alkoxy groups, monomers with phosphoric acid groups, monomers with sulfonic acid groups, monomers with phenyl groups and monomers with silane groups It may include one or more of.

Monomers having ethylene oxide may be at least one (meth) acrylate monomer containing an ethylene oxide group (-CH ₂ CH ₂ O-). For example, polyethylene oxide monomethyl ether (meth) acrylate, polyethylene oxide monoethyl ether (meth) acrylate, polyethylene oxide monopropyl ether (meth) acrylate, polyethylene oxide monobutyl ether (meth) acrylate, polyethylene oxide mono Pentyl ether (meth) acrylate, polyethylene oxide dimethyl ether (meth) acrylate, polyethylene oxide diethyl ether (meth) acrylate, polyethylene oxide monoisopropyl ether (meth) acrylate, polyethylene oxide monoisobutyl ether (meth) It may be a polyethylene oxide alkyl ether (meth) acrylate, such as acrylate, polyethylene oxide monotertbutyl ether (meth) acrylate, but is not necessarily limited thereto.

Monomers with propylene oxide include polypropylene oxide monomethyl ether (meth) acrylate, polypropylene oxide monoethyl ether (meth) acrylate, polypropylene oxide monopropyl ether (meth) acrylate, polypropylene oxide monobutyl ether (meth ) Acrylate, polypropylene oxide monopentyl ether (meth) acrylate, polypropylene oxide dimethyl ether (meth) acrylate, polypropylene oxide diethyl ether (meth) acrylate, polypropylene oxide monoisopropyl ether (meth) acrylic Polypropylene oxide alkylether (meth) acrylates, such as latex, polypropylene oxide monoisobutyl ether (meth) acrylate, polypropylene oxide monotertbutyl ether (meth) acrylate, but are not necessarily limited thereto. no All.

Monomers having an amine group include monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate, monoethylaminopropyl (meth) acrylate, dimethylaminoethyl ( Amine group-containing (meth) acrylic systems, such as meth) acrylate, diethylaminoethyl (meth) acrylate, N-tert- butylaminoethyl (meth) acrylate, and methacryloxyethyl trimethylammonium chloride (meth) acrylate It may be a monomer, but is not necessarily limited thereto.

Monomers having an amide group include (meth) acrylamide, N-methylacrylamide, N-methylmethacrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N, N-methylene Amide group-containing (meth) acrylic monomers such as bis (meth) acrylamide and 2-hydroxyethylacrylamide may be used, but are not necessarily limited thereto.

Monomers having an alkoxy group include 2-methoxy ethyl (meth) acrylate, 2-methoxypropyl (meth) acrylate, 2-ethoxypropyl (meth) acrylate, 2-butoxypropyl (meth) acrylate, 2 -Methoxypentyl (meth) acrylate, 2-ethoxypentyl (meth) acrylate, 2-butoxyhexyl (meth) acrylate, 3-methoxypentyl (meth) acrylate, 3-ethoxypentyl (meth ) Acrylate, 3-butoxyhexyl (meth) acrylate, 2-acetoacetoxyethyl (meth) acrylate, but are not necessarily limited thereto.

Monomers having a phosphoric acid group include 2-methacryloyloxyethyldiphenyl phosphate (meth) acrylate, trimethacryloyloxyethyl phosphate (meth) acrylate, triacryloyloxyethyl phosphate (meth) acrylate, and the like. It may be an acrylic monomer having a phosphoric acid group, but is not necessarily limited thereto.

The monomer having a sulfonic acid group may be an acrylic monomer having a sulfonic acid group such as sodium sulfopropyl (meth) acrylate, sodium 2-sulfoethyl (meth) acrylate and sodium 2-acrylamido-2-methylpropane sulfonate. However, the present invention is not limited thereto.

The monomer having a phenyl group may be an acrylic vinyl monomer having a phenyl group such as p-tert-butylphenyl (meth) acrylate, o-biphenyl (meth) acrylate, phenoxyethyl (meth) acrylate, but is not limited thereto. It doesn't happen.

The monomer having a silane group includes silane groups such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethyl) silane, vinyltriacetoxysilane, and (meth) acryloyloxypropyltrimethoxysilane. It may be a vinyl monomer having, but is not necessarily limited thereto.

The (meth) acrylic copolymer may be a non-carboxylic acid copolymer having no carboxylic acid group in order to secure the resistance change rate. However, the monomer mixture may further lower the resistance change rate by including more than 0% by weight and less than 1% by weight of the (meth) acrylic monomer having a carboxylic acid group. The (meth) acrylic monomer having a carboxylic acid group may include (meth) acrylic acid and the like.

The initiator may form a (meth) acrylic copolymer or cure the (meth) acrylic copolymer from the monomer mixture. The initiator may use a photopolymerization initiator or a thermal polymerization initiator. The initiator may use the same or different initiator as the initiator used in preparing the prepolymer to partially polymerize. As said photoinitiator, as long as it can induce the polymerization reaction of the radically polymerizable compound mentioned above in the hardening process by light irradiation etc., and can implement | achieve a 2nd crosslinked structure, any can be used. For example, benzoin type, acetophenone type, hydroxy ketone type, amino ketone type, or phosphine oxide type photoinitiator can be used, and specifically, benzoin, benzoin methyl ether, benzoin ethyl ether, benzo Phosphorus isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylanino acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenyl Acetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1one, 1-hydroxycyclohexylphenylketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino- Propane-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4-nonsidiethylaminobenzophenone, dichloro Benzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxane , 2,4-dimethyl thioxanthone, 2,4-diethyl thioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethylamino benzoic acid ester, oligo [2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone], 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, etc. are mentioned. In the present application, one or more of the above may be used, but is not limited thereto. The type of the thermal polymerization initiator is not particularly limited as long as it can induce a polymerization reaction of the polymerizable compound to implement a second crosslinked structure. For example, an azo compound, a peroxide compound, or a redox system is used. Conventional initiators such as compounds can be used. Examples of the azo compound in the above are 2,2-azobis (2-methylbutyronitrile), 2,2-triazobis (isobutyronitrile), 2,2-triazobis (2,4-dimethyl Valeronitrile), 2,2-nitazobis-2-hydroxymethylpropionitrile, dimethyl-2,2-methylazobis (2-methylpropionate), and 2,2-pioazobis (4- Methoxy-2,4-dimethylvaleronitrile) and the like, and examples of the peroxide-based compound include inorganic peroxides such as potassium peroxide, ammonium persulfate or hydrogen peroxide; Or diacyl peroxide, peroxy dicarbonate, peroxy ester, tetramethylbutylperoxy neodecanoate, bis (4-butylcyclohexyl) peroxydicarbonate, di (2-ethylhexyl) peroxy carbonate, butylper Oxy neodecanoate, dipropyl peroxy dicarbonate, diisopropyl peroxy dicarbonate, diethoxyethyl peroxy dicarbonate, diethoxyhexyl peroxy dicarbonate, hexyl peroxy dicarbonate, dimethoxybutyl peroxy dicarbonate , Bis (3-methoxy-3-methoxybutyl) peroxy dicarbonate, dibutyl peroxy dicarbonate, dicetyl peroxy dicarbonate, dimyristyl peroxy dicarbonate, 1,1 , 3,3-tetramethylbutyl peroxypivalate, hexyl peroxy pivalate, butyl peroxy pivalate, trimethyl hexanoyl peroxide, dimethyl hydroxybutyl peroxy Odecanoate, amyl peroxyneodecanoate, butyl peroxyneodecanoate, t-butylperoxy neoheptanoate, amylperoxy pivalate, t-butylperoxy pivalate, t-amyl Organic peroxides such as peroxy-2-ethylhexanoate, lauryl peroxide, dilauuroyl peroxide, didecanoyl peroxide, benzoyl peroxide or dibenzoyl peroxide, and the like. Examples of the compound include, but are not limited to, a mixture using a peroxide compound and a reducing agent in combination. In the present application, one kind or a mixture of two or more kinds of the azo-based, peroxide-based or redox-based compounds may be used. The initiator may be included in an amount of 0.01 to 5 parts by weight, specifically 0.05 to 3 parts by weight, more specifically 0.1 to 1 part by weight, based on 100 parts by weight of the monomer mixture for the (meth) acrylic copolymer. In the above range, the curing reaction may proceed completely, remaining amount of initiator may remain to prevent the transmittance of the pressure-sensitive adhesive film from being lowered, and also may lower bubble generation and have excellent reactivity.

The pressure-sensitive adhesive composition may further include a crosslinking agent. The crosslinking agent may increase the degree of crosslinking of the pressure-sensitive adhesive composition to increase the mechanical strength of the pressure-sensitive adhesive film. The crosslinking agent may comprise a polyfunctional (meth) acrylate that is curable with active energy rays. In an embodiment, the crosslinking agent is 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentylglycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, Neopentylglycol adipate di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylate, ethylene oxide modified di (meth) ) Acrylate, di (meth) acryloxy ethyl isocyanurate, allylated cyclohexyl di (meth) acrylate, tricyclodecanedimethanol (meth) acrylate, dimethylol dicyclopentanedi (meth) acrylate, Ethylene oxide modified hexahydrophthalic acid di (meth) acrylate, tricyclodecane dimethanol (meth) acrylate, neopentyl glycol modified trimethylpropane di (meth) acrylate, ah Bifunctional acrylates such as adamantane di (meth) acrylate or 9,9-bis [4- (2-acryloyloxyethoxy) phenyl] fluorene; Trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide Trifunctional acrylates such as modified trimethylolpropane tri (meth) acrylate, trifunctional urethane (meth) acrylate or tris (meth) acryloxyethyl isocyanurate; Tetrafunctional acrylates such as diglycerin tetra (meth) acrylate or pentaerythritol tetra (meth) acrylate; 5-functional acrylates, such as dipentaerythritol penta (meth) acrylate; And dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate or urethane (meth) acrylate (ex. Isocyanate monomers and trimethylolpropane tri (meth) acrylate 6 functional acrylates such as reactants, etc., but are not limited thereto.They may be used singly or in mixture of two or more. Preferably, the crosslinking agent may be a polyfunctional (meth) acrylate of a polyhydric alcohol. The crosslinking agent may be included in an amount of 0 to 10 parts by weight, specifically 0.03 to 7 parts by weight, specifically 0.1 to 5 parts by weight, based on 100 parts by weight of the monomer mixture for the (meth) acrylic copolymer. In the range, there is an effect of excellent adhesion and increased reliability.

The pressure-sensitive adhesive composition may further include a silane coupling agent. Silane coupling agents can be used conventionally known to those skilled in the art. For example, 3-glycidoxy propyl trimethoxysilane, 3-glycidoxy propyl triethoxysilane, 3-glycidoxy propylmethyl dimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltri Silicon compounds having an epoxy structure such as methoxysilane; Polymerizable unsaturated group-containing silicon compounds such as vinyl trimethoxy silane, vinyl triethoxy silane, and (meth) acryloxy propyl trimethoxysilane; Amino group-containing silicon compounds such as 3-aminopropyl trimethoxysilane, N- (2-aminoethyl) -3-aminopropyl trimethoxysilane, N- (2-aminoethyl) -3-aminopropyl methyl dimethoxysilane ; And 3-chloro propyl trimethoxysilane and the like may include one or more selected from the group consisting of, but is not limited thereto. Preferably, a silane coupling agent having an epoxy structure can be used. The silane coupling agent may be included in an amount of 0 to 0.1 parts by weight, specifically 0.05 to 0.1 parts by weight, based on 100 parts by weight of the monomer mixture for the (meth) acrylic copolymer. There is an effect of increasing the reliability in the above range.

The pressure-sensitive adhesive composition may optionally include a curing accelerator, an ionic liquid, a lithium salt, an inorganic filler, a softener, a molecular weight regulator, an antioxidant, an antioxidant, a stabilizer, a tackifying resin, a modified resin (polyol resin, phenol resin, acrylic resin, polyester resin) , Polyolefin resins, epoxy resins, epoxidized polybutadiene resins, etc.), leveling agents, antifoaming agents, plasticizers, dyes, pigments (colored pigments, sieving pigments, etc.), treatment agents, sunscreen agents, fluorescent brighteners, dispersants, thermal stabilizers, Conventional additives such as light stabilizers, ultraviolet absorbers, antistatic agents, flocculants, lubricants and solvents may be further included.

The pressure-sensitive adhesive composition may have a viscosity of 25 ° C. to 300 cPs to 50,000 cPs, and may have an effect of obtaining excellent coating properties and thickness uniformity in the above range.

The pressure-sensitive adhesive composition may be prepared by partially polymerizing a monomer mixture for a (meth) acrylic copolymer and including an initiator. The crosslinking agent, silane coupling agent, additive, etc. which were mentioned above may further be included. The pressure-sensitive adhesive composition partially polymerizes the monomer mixture for the (meth) acrylic copolymer to prepare a viscous liquid comprising a hydroxyl group and an alkyl group-containing (meth) acrylic copolymer (prepolymer) and the unpolymerized monomer mixture, followed by an initiator. It can be prepared to include. The crosslinking agent, silane coupling agent, additive, etc. which were mentioned above may further be included. Partial polymerization can include solution polymerization, suspension polymerization, photopolymerization, bulk polymerization, or emulsion polymerization. Specifically, solution polymerization may be performed at 50 ° C. to 100 ° C. by adding an initiator to the monomer mixture. The initiator may be an acetophenone-based radical photopolymerization initiator including 2,2-dimethoxy-2-phenylacetophenone and the like, but is not limited thereto. Partial polymerization may be polymerized at 25 ° C. with a viscosity of 1,000 cPs to 10,000 cPs, specifically 4,000 cPs to 9,000 cPs.

The pressure-sensitive adhesive film may be prepared by a conventional method. For example, the pressure-sensitive adhesive composition may be prepared by coating a release film and curing the same. Curing may include irradiation of the irradiation dose 400mJ / cm ² to 3000mJ / cm ² at a wavelength of 300nm to 400nm into a low-pressure lamp in an oxygen-free state.

Hereinafter, an adhesive film of another embodiment of the present invention will be described.

In the adhesive film of the present embodiment, the ratio of tan δ of Formula 1 may be 1 to 2, the ratio of tan δ of Formula 2 is 0.1 to 1.5, and the restoring force may be 85% or more, specifically, 85% to 90%. Since the pressure-sensitive adhesive film has a ratio of tan δ of Formula 1 and Formula 2, it may exhibit good folding property even at low temperature and room temperature. Since the adhesive film has a restoring force of 85% or more, the adhesive film has good restoring force, and thus, even when the adhesive film is restored to its original state after long-term folding of the adhesive film, wrinkles may not occur in the adhesive film. Except that the restoring force is more than 85% is substantially the same as the pressure-sensitive adhesive film according to an embodiment of the present invention.

The adhesive film of this embodiment may include organic nanoparticles. The organic nanoparticles may have good folding properties at room temperature and high temperature of the pressure-sensitive adhesive film, have excellent low-temperature and / or room temperature viscoelasticity, and have a crosslinked structure to stably express high-temperature viscoelasticity of the pressure-sensitive adhesive film. . In addition, the organic nanoparticles may increase the storage modulus at a high temperature to increase the reliability at a high temperature.

The organic nanoparticles may have a specific average particle diameter, and the difference in refractive index between the organic nanoparticles and the (meth) acrylic copolymer may be small. Therefore, although the adhesive film contains organic nanoparticles, the adhesive film can secure high transparency. The organic nanoparticles may have an average particle diameter of 10 nm to 400 nm, specifically 10 nm to 300 nm, more specifically 10 nm to 200 nm, and more specifically 50 nm to 150 nm. In the above range, it is possible to prevent the aggregation of the organic nanoparticles, does not affect the folding of the adhesive film, the transparency of the adhesive film may be good. The organic nanoparticles may have a refractive index difference of 0.05 or less, specifically 0 or more and 0.03 or less, specifically 0 or more and 0.02 or less. In the above range, the transparency of the pressure-sensitive adhesive film may be excellent. The organic nanoparticles may have a refractive index of 1.40 to 1.70, specifically 1.48 to 1.60. In the above range, the transparency of the adhesive film may be excellent.

In one embodiment, the organic nanoparticles are core-shell organic nanoparticles, and the core and the shell may satisfy the following Equation 6: When the core-shell-type particle form as described above, the foldability of the adhesive film is good, elastic It can have an effect on the balance physical properties of and flexibility.

<Equation 6>

Tg (c) <Tg (s)

(In Formula 6, Tg (c) is the glass transition temperature (unit: ° C) of the core, Tg (s) is the glass transition temperature (unit: ° C) of the shell).

As used herein, "shell" refers to the outermost layer of organic nanoparticles. The core may be one spherical particle. However, the core may further comprise an additional layer surrounding the spherical particles if it has the above glass transition temperature.

Specifically, the glass transition temperature of the core may be -150 ℃ to 10 ℃, specifically -150 ℃ to -5 ℃, more specifically -150 ℃ to -20 ℃. In the above range may be a low temperature and / or room temperature viscoelastic effect of the adhesive film. The core may comprise at least one of polyalkyl (meth) acrylates or polysiloxanes having the above glass transition temperature.

Polyalkyl (meth) acrylates are polymethylacrylate, polyethylacrylate, polypropylacrylate, polybutylacrylate, polyisopropylacrylate, polyhexyl acrylate, polyhexyl methacrylate, polyethylhexyl acrylate And polyethylhexyl methacrylate, but are not necessarily limited thereto.

The polysiloxane can be, for example, an organosiloxane (co) polymer. The organosiloxane (co) polymer may be one which is not crosslinked, or a crosslinked (co) polymer may be used. Crosslinked organosiloxane (co) polymers can be used for impact resistance and colorability. This is a crosslinked organosiloxane, specifically, crosslinked dimethylsiloxane, methylphenylsiloxane, diphenylsiloxane or a mixture of two or more thereof may be used. The refractive index of 1.41 to 1.50 can be adjusted by using a form in which two or more organosiloxanes are copolymerized.

The crosslinking state of the organosiloxane (co) polymer can be judged with the degree of dissolution by various organic solvents. The deeper the crosslinking state, the smaller the degree of dissolution by the solvent. Acetone or toluene may be used as a solvent for determining the crosslinking state. Specifically, the organosiloxane (co) polymer may have a portion which is not dissolved by acetone or toluene. The insoluble component of the organosiloxane copolymer to toluene may be 30% or more.

Additionally, the organosiloxane (co) polymer may further include an alkylacrylate crosspolymer. As the alkyl acrylate crosspolymer, methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate and the like can be used. For example, n-butyl acrylate or 2-ethylhexyl acrylate having a low glass transition temperature can be used.

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

The core may be included in 30 to 99% by weight, specifically 40 to 95% by weight, more specifically 50 to 90% by weight of the organic nanoparticles. In the above range, the folding property of the adhesive film in a wide temperature range may be good.

The shell may comprise 1% to 70% by weight, specifically 5% to 60% by weight, and more specifically 10% to 50% by weight of the organic nanoparticles. In the above range, the folding property of the adhesive film in a wide temperature range may be good.

Organic nanoparticles can be prepared by emulsion polymerization method.

The organic nanoparticles may be included in an amount of 0.1 parts by weight to 20 parts by weight, specifically 0.5 parts by weight to 10 parts by weight, and more specifically 0.5 parts by weight to 5 parts by weight, based on 100 parts by weight of the monomer mixture for the (meth) acrylic copolymer. In the above range, the viscoelasticity and modulus of the pressure-sensitive adhesive film and the restoring force can be balanced, there may be an excellent effect of folding at high temperatures.

The pressure-sensitive adhesive film of this embodiment may be formed of a pressure-sensitive adhesive composition comprising a monomer mixture, an initiator, and organic nanoparticles including a (meth) acrylic acid ester having a hydroxyl group and a (meth) acrylic acid ester having an alkyl group. It is substantially the same as the pressure-sensitive adhesive composition described above except that it further comprises organic nanoparticles.

An optical member according to an embodiment of the present invention includes an optical film, and an adhesive film formed on at least one surface of the optical film, the adhesive film may include an adhesive film according to embodiments of the present invention. Thus, the optical member can be used in a flexible display device having good bending and / or good folding characteristics.

In one embodiment, the optical film provides a constant optical function of the display device, such as polarization, optical compensation, display quality improvement, and / or conductivity, the optical film is a polarizing plate, color filter, retardation film, elliptical polarizing film, Transparent conductive films including reflective films, antireflection films, compensation films, brightness enhancement films, alignment films, light diffusion films, glass scattering prevention films, surface protection films, plastic LCD substrates, indium tin oxide (ITO) films, and the like. Can be. The manufacturing method of the optical film can be easily manufactured by those skilled in the art to which the present invention pertains.

For example, a touch panel may be formed by attaching the touch pad to a window or an optical film using an adhesive film. Or it may be applied as an adhesive film to a conventional polarizing film as in the prior art.

In another embodiment, the optical film is an optically transparent optical film, the optical member including the optical film and the adhesive film may serve as a support layer of the display element. For example, the display element may include a window film or the like. The window film may include the optical member and a window coating layer (eg, a silicon based coating layer) formed on the optical member. The window film can be a flexible window film. Specifically, the optical film has a total light transmittance of 90% or more in the visible region, and includes a cellulose resin including triacetyl cellulose, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, and the like. Formed of at least one of a poly (meth) acrylate resin, a cyclic olefin polymer resin, an acrylic resin, a polyamide resin, including a polyester resin, a polycarbonate resin, a polyimide resin, a polystyrene resin, a polymethylmethacrylate, and the like It may be a film. 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. It can be used as the support layer of the display element in the above range.

The optical member may be an optical film and two layers of optical members having an adhesive film formed on one surface of the optical film. Alternatively, the optical member may include two or more optical films, and at least two or more of the optical films may be three or more film laminates laminated by the adhesive film of the present invention.

In one embodiment, the optical member may be a first optical film, a second optical film, and a three-layer film laminate in which the first optical film and the second optical film are laminated by the adhesive film of the present invention. Each of the first optical film and the second optical film may be a film formed of at least one of polyethylene terephthalate resin, polycarbonate resin, polyimide resin, poly (meth) acrylate resin, cyclic olefin polymer resin, and acrylic resin. Can be. Each of the first optical film and the second optical film has a thickness of 10 μm to 100 μm, specifically 20 μm to 75 μm, more specifically 30 μm to 50 μm, and the adhesive film has a thickness of 10 μm to 100 μm. This can be In the above range, it can be effective to maximize the impact resistance while maintaining good folding properties. The first optical film and the second optical film may be the same or different in thickness and material, respectively.

The optical display device of the present invention may include the adhesive film of the present invention. The optical display device may include an organic light emitting display device, a liquid crystal display device and the like. The optical display device may include a flexible display device. However, the optical display device may include a non-flexible display device.

Hereinafter, a flexible display device according to an exemplary embodiment of the present invention will be described with reference to FIG. 5. 5 is a cross-sectional view of a flexible display device according to an exemplary embodiment of the present invention.

Referring to FIG. 5, the flexible display apparatus 100 according to an exemplary embodiment of the present invention may include a display 110, an adhesive layer 120, a polarizer 130, a touch screen panel 140, and a flexible window film ( 150), and the adhesive layer 120 may include an adhesive film according to an embodiment of the present invention.

The display unit 110 is for driving the flexible display apparatus 100 and may include an optical element including a substrate and an OLED, an LED, or an LCD element formed on the substrate. Although not shown in FIG. 5, the display unit 110 may include a lower substrate, a thin film transistor, an organic light emitting diode, a planarization layer, a protective film, and an insulating film.

The polarizer 130 may implement polarization of internal light or prevent reflection of external light to implement a display or increase a contrast ratio of the display. The polarizing plate may be composed of a polarizer alone. Alternatively, the polarizer may include a polarizer and a protective film formed on one or both sides of the polarizer. Alternatively, the polarizing plate may include a polarizer and a protective coating layer formed on one or both surfaces of the polarizer. The polarizer, the protective film, and the protective coating layer may use a conventional one known to those skilled in the art.

The touch screen panel 140 generates an electrical signal by detecting a change in capacitance generated when a human body or a conductor such as a stylus touches the touch screen panel. The display 110 may be driven by the signal. The touch screen panel 140 is formed by patterning a flexible and conductive conductor, and may include a second sensor electrode formed between the first sensor electrode and the first sensor electrode to cross the first sensor electrode. have. The conductor for the touch screen panel 340 may include, but is not limited to, metal nanowires, conductive polymers, carbon nanotubes, and the like.

The flexible window film 150 may be formed on the outermost side of the flexible display device 300 to protect the display device.

Although not shown in FIG. 5, a pressure-sensitive adhesive layer is further formed between the polarizing plate 130 and the touch screen panel 140 and / or between the touch screen panel 140 and the flexible window film 150 to form a polarizing plate, a touch screen panel, and a flexible display. The bond between the window films can be strengthened. In one embodiment, the pressure-sensitive adhesive layer may be formed of a pressure-sensitive adhesive composition comprising a (meth) acrylate-based resin, a curing agent, an initiator and a silane coupling agent. In another embodiment, the adhesive layer may include an adhesive film according to an embodiment of the present invention. In addition, although not shown in FIG. 5, a polarizer may be further formed below the display unit 110 to implement polarized light.

Hereinafter, the configuration and operation of the present invention through the preferred embodiment of the present invention will be described in more detail. However, this is presented as a preferred example of the present invention and should not be construed as limiting the present invention by any means.

Production Example

By emulsion polymerization method, organic nanoparticles were prepared. The core is polybutyl acrylate, the shell is polymethyl methacrylate, the shell is 35% by weight of the organic nanoparticles, the core is 65% by weight of the organic nanoparticles, the average particle diameter is 100nm, the organic nanoparticles having a refractive index of 1.48 Was prepared.

Example  One

100 parts by weight of a monomer mixture comprising 20 parts by weight of 4-hydroxybutyl acrylate (4-HBA) and 80 parts by weight of 2-ethylhexyl acrylate (2-EHA), Irgacure 651 (2,2-dimethoxy- as an initiator 0.03 parts by weight of 2-phenylacetophenone, BASF) was mixed well in the reactor. After exchange of dissolved oxygen in the reactor with nitrogen gas, the mixture was partially polymerized by ultraviolet irradiation using a low pressure mercury lamp to prepare a viscous liquid having a viscosity of 5,000 cps at 25 ° C. An adhesive composition was prepared by adding 0.5 parts by weight of an initiator Irgacure 184 (1-hydroxycyclohexylphenyl ketone, BASF) and mixing the viscous liquid. The pressure-sensitive adhesive composition was applied to a PET (polyethylene terephthalate) film, which is a release film, and irradiated with an ultraviolet light amount of 2000 mJ / cm ² to prepare a pressure-sensitive adhesive film and a pressure-sensitive adhesive sheet having a thickness of 50 μm.

Example  2

17 parts by weight of 4-HBA, 100 parts by weight of a monomer mixture including 83 parts by weight of 2-EHA, 1 part by weight of organic nanoparticles of the preparation example, Irgacure 651 (2,2-dimethoxy-2-phenylacetophenone, BASF Corporation as an initiator ) 0.03 parts by weight was mixed well in the reactor. After exchange of dissolved oxygen in the reactor with nitrogen gas, the mixture was partially polymerized by ultraviolet irradiation using a low pressure mercury lamp for a few minutes to prepare a viscous liquid having a viscosity of 5,000 cps at 25 ° C. An adhesive composition was prepared by adding 0.5 parts by weight of an initiator Irgacure184 (1-hydroxycyclohexylphenyl ketone, BASF) and mixing the viscous liquid. An adhesive sheet was prepared in the same manner as in Example 1.

Example  3

In Example 2, an adhesive sheet was prepared in the same manner except that 100 parts by weight of the monomer mixture including 20 parts by weight of 4-HBA and 80 parts by weight of 2-EHA were used.

Comparative example  One

100 parts by weight of a monomer mixture comprising 54 parts by weight of 2-EHA, 20 parts by weight of isobornyl acrylate (IBOA), 25 parts by weight of 2-hydroxyethyl acrylate (2-HEA), and 1 part by weight of acrylic acid (AA), 0.03 parts by weight of Irgacure651 (2,2-dimethoxy-2-phenylacetophenone, BASF) as an initiator was mixed well in the reactor. After exchange of dissolved oxygen in the reactor with nitrogen gas, the mixture was partially polymerized by ultraviolet irradiation using a low pressure mercury lamp for a few minutes to prepare a viscous liquid having a viscosity of 5,000 cps at 25 ° C. An adhesive composition was prepared by adding 0.5 parts by weight of an initiator Irgacure184 (1-hydroxycyclohexylphenyl ketone, BASF) and mixing the viscous liquid. The pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 prepared pressure-sensitive adhesive composition.

Comparative example  2

In Comparative Example 1, an adhesive sheet was prepared in the same manner except that 100 parts by weight of the monomer mixture including 60 parts by weight of 2-EHA, 35 parts by weight of 2-HEA, and 5 parts by weight of acryloyl morpholine (ACMO) was used. .

Comparative example  3 lessons Comparative example  4

In Comparative Example 1, Comparative Example 2, the pressure-sensitive adhesive sheet was prepared in the same manner except for changing the monomer mixture as shown in Table 2 below.

The composition of the pressure-sensitive adhesive film of Examples and Comparative Examples is shown in Table 1 and Table 2. The physical properties of Table 1 and Table 2 were evaluated for the adhesive film.

(1) Modulus: Using an ARES (Anton Paar MCR-501) dynamic viscoelasticity measuring device, the shear rate is increased from 0.1 rad / sec to 100 rad / sec at a constant temperature of -20 ° C., with an auto strain condition of 1% strain. Modulus was measured. After removing the release film in Examples and Comparative Examples, the adhesive film having a thickness of 50 μm was laminated to a thickness of 500 μm, and the laminate was punched out using a perforator having a diameter of 8 mm to be used as a specimen for measuring modulus. Storage modulus (G ′) and loss modulus (G ″) were calculated and tan δ was calculated as G ″ / G '. The ratio of tan δ was calculated according to Equations 1 and 2 above. The ratio of modulus, tan δ, and tan δ was obtained in the same manner as above under constant temperature of 25 ° C. and constant temperature of 80 ° C.

(2) Resistance change rate: Referring to FIG. 1, a polyethylene terephthalate (PET) film coated with indium tin oxide (ITO) is laminated on a glass plate, and the adhesive film and PET film obtained in (1) on the middle part of the ITO surface. The laminate was placed, and electrodes were formed at both ends of the ITO film without the adhesive film by using a silver paste to prepare a specimen. Initial resistance (P ¹ ) was measured by connecting wires to both electrodes of the prepared specimen. The specimen was left at 60 ° C. and 95% relative humidity for 250 hours and then the resistance (P ² ) was measured. Equation 4 was used to obtain the resistance change rate.

(3) Peeling strength: A corona treatment (total dose: 156 dose) was performed on a PET film having a width x length x thickness (150 mm x 25 mm x 75 µm) while discharging plasma at a dose of 78 doses using a corona treatment machine. The adhesive film sample was obtained by the magnitude | size of 100 mmx25mmx50micrometer (width x length x thickness) from the adhesive sheet of an Example and a comparative example. The corona treated surface of the PET film was laminated on both surfaces of the adhesive film sample, thereby preparing the specimen shown in FIG. The specimens were autoclaved at pressure of 3.5 bar at 50 ° C. for 1000 seconds and the specimens were fixed in a TA.XT_Plus Texture Analyzer (Stable Micro System). Referring to FIG. 2 (b), one PET film was fixed at 25 ° C. in TA.XT_Plus Texture Analyzer and the other PET film was pulled at a rate of 50 mm / min to measure T-Peel peel strength.

(4) Haze: Haze meter (Nippon Denshoku company model NDH 5000) equipment was used. Haze was measured for a 50 μm thick adhesive film according to ASTM D 1003-95 5 (“Standard Test for Haze and Luminous Transmittance of Transparent Plastic”).

(5) Gel fraction: The release film was released from the adhesive sheets of Examples and Comparative Examples to obtain an adhesive film. The gel fraction of the adhesive film 1g was measured according to Equation 3 above. At this time, a 100 mL photosphere bottle was used as the sample bottle, and a mesh size of 200 mesh was used as the wire mesh.

(6) Restoration force: The release film was released from the adhesive sheets of Examples and Comparative Examples to obtain an adhesive film. Resilience was evaluated by TA.XT_Plus Texture Analyzer (Stable Micro System) at 25 ° C.

Referring to FIG. 3, first and second ends of a PET (polyethylene terephthalate) film (thickness: 75 μm) having a width x length (50 mm × 20 mm) by a pressure-sensitive adhesive film having a width × length × thickness (20mm × 20mm × 50μm), respectively When referring to the distal end and the second distal end, the distal ends of the two PET films are adhered to each other by an adhesive film of horizontal x vertical (20 mm x 20 mm), and the second end of the first end / adhesive film / PET film of the PET film. It is adhered in the order of, and the contact area between the PET film and the pressure-sensitive adhesive film is measured as a specimen having a width x length (20 mm x 20 mm). The jig was fixed to both ends of the PET film of the specimen. The contact area between the PET film and the jig was set to be horizontal x vertical (15 mm x 20 mm).

3 and 4, at 25 ° C., one jig is fixed and the other jig is 1000% of the length (adhesive film) of the thickness (initial thickness: X ₀ , unit: μm) of the adhesive film at a speed of 300 mm / min. After pulling up to 10 times the initial thickness of, X ₃ , unit: ㎛) and maintained for 10 seconds, then restored to the speed (300mm / min) at the same speed as the pulled pressure-sensitive adhesive film when a 0kPa force is applied to the adhesive film Extended length (X ₂ , unit: μm) is obtained. Referring to FIG. 4, a graph is obtained using the length of the adhesive film as the X axis and the force applied to the adhesive film as the Y axis. The restoring force is calculated according to Equation 5 above.

(6) Tg of adhesive film: 15mg (on 6mm Al Pan) sample was made with respect to the adhesive film of the Example and the comparative example, and it heated up to 180 degreeC by the temperature increase rate of 20 degreeC / min in nitrogen atmosphere (50mL / min). After cooling to -100 ° C (first heating condition (1st run)), the glass transition temperature (Tg) of the pressure-sensitive adhesive film was measured using the DSC Discovery of TA Instrument while raising the temperature to 100 ° C at a heating rate of 10 ° C / min. It was.

(7) Folding: Both release films were separated from the pressure-sensitive adhesive sheets prepared in Examples and Comparative Examples to obtain a pressure-sensitive adhesive film (thickness: 50 μm). A pressure-sensitive adhesive film (thickness: 50 μm) is placed between the corona-treated 50 μm polyethylene terephthalate (PET) films, and the corona-treated side of the PET film is in contact with the pressure-sensitive adhesive film and attached with a roller, followed by room temperature for 12 hours. Aging (aging) at, and cut to the horizontal × vertical (70mm × 140mm) size to prepare a specimen. The cut specimen is fixed to a bendability evaluation device (CFT-200, Covotech) using an adhesive (4965, Tesa Co., Ltd.), and the length of the specimen (140 mm) at -20 ° C or 25 ° C to have a radius of curvature of 3 mm. Bending was repeated at a rate of 30 cycles per minute (bending and releasing the adhesive film in half once in one cycle). When the bending was repeated with 1 cycle, the number of cycles for generating cracks in the polyethylene terephthalate film was visually measured. An adhesive film having a high minimum cycle number means an adhesive film which can easily relax the stress of the polyethylene terephthalate film due to bending. If the initial cycle number is 100,000 or more, ○, 70,000 or more and less than 100,000 times, △, and 70,000 or less times, X. Folding was evaluated at -20 ° C and 25 ° C, respectively.

(8) Durability: The release film was released from the adhesive sheets of Examples and Comparative Examples to obtain an adhesive film. A pressure-sensitive adhesive film was laminated on the ITO film, and a glass or polycarbonate film was laminated on the pressure-sensitive adhesive film to prepare a specimen. After autoclaving the specimens, the specimens were allowed to stand at 60 ° C. and 90% relative humidity for 500 hours. Lifting, peeling, or thinning of bubbles between the adhesive film as the adherend surface and the glass or polycarbonate film was visually evaluated. When there was no bubble or peeling, (circle) and the case where there existed some bubbles or peeling, (triangle | delta) and the case where there were a lot of bubbles and peeling were evaluated as x.

Example 1 Example 2 Example 3 Monomer 4-HBA (parts by weight) 20 17 20 2-EHA (parts by weight) 80 83 80 Organic Nanoparticles (parts by weight) 0 One One -20 ℃ G '(kPa, 1rad / sec) 72 68 74 tan δ (1 rad / sec) 0.43 0.59 0.53 G '(kPa, 100rad / sec) 215 832 951 tan δ (100 rad / sec) 0.14 0.69 0.46 ratio of tan δ 0.33 1.17 0.87 25 ℃ G '(kPa, 1rad / sec) 27 28 31 tan δ (1 rad / sec) 0.25 0.26 0.24 G '(kPa, 100rad / sec) 61.2 60.9 65 tan δ (100 rad / sec) 0.39 0.41 0.41 ratio of tan δ 1.56 1.58 1.71 80 ℃ G '(kPa, 1rad / sec) 18 19 21 Resistance change rate (%) 3 3 2 Peel Strength (gf / inch) 1500 1400 1630 Gel fraction (%) 78 75 74 Haze (%) 0.57 0.7 0.92 dynamic stability(%) 80 85 90 Tg (℃) of adhesive film -56 -58 -56 -20 ℃ Folding ○
(100,000 times) ○
(100,000 times) ○
(100,000 times) 25 ℃ Folding ○
(100,000 times) ○
(100,000 times) ○
(100,000 times) durability ○ ○ ○

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Monomer 2-EHA (parts by weight) 54 60 57 84 IBOA (parts by weight) 20 - 18 - 2-HEA (parts by weight) 25 35 22 15 AA (part by weight) One - 3 One ACMO (part by weight) - 5 - - -20 ℃ G '(kPa, 1rad / sec) 550 580 550 430 tan δ (1 rad / sec) 0.98 1.3 One 0.85 G '(kPa, 100rad / sec) Not measurable Not measurable Not measurable Not measurable tan δ (100 rad / sec) Not measurable Not measurable Not measurable Not measurable ratio of tan δ Not measurable Not measurable Not measurable Not measurable 25 ℃ G '(kPa, 1rad / sec) 31.5 17 23.8 48 tan δ (1 rad / sec) 0.18 0.14 0.235 0.325 G '(kPa, 100rad / sec) 54 32 70.1 185 tan δ (100 rad / sec) 0.34 0.55 0.89 1.04 ratio of tan δ 1.89 3.93 3.79 3.20 80 ℃ G '(kPa, 1rad / sec) 31.5 35.5 19.9 24.6 Resistance change rate (%) 3 2 5 3 Peel Strength (gf / inch) 1900 2700 2400 2000 Gel fraction (%) 85 74 74 92 Haze (%) 0.57 0.57 0.57 0.57 dynamic stability(%) 75 88 80 74 Tg (℃) of adhesive film -20 -30 -23 -50 -20 ℃ Folding X
(Less than 10 times) X
(Less than 10 times) X
(Less than 10 times) X
(Less than 100 times) 25 ℃ Folding X
(40000 times) X
(500 times) X
(Less than 1000 times) X
(10000 Episodes) durability ○ ○ ○ ○

As shown in Table 1, the pressure-sensitive adhesive film according to this embodiment included tan δ in the range of the present invention, and showed good folding property at room temperature and low temperature. In addition, Examples 2 and 3 containing organic nanoparticles were also optically transparent with low haze. In addition, Examples 2 and 3 including the organic nanoparticles has a high restoring force, even when the adhesive film is placed in its original state after being folded for a long time, wrinkles may not occur in the adhesive film.

On the other hand, Comparative Example 1 to Comparative Example 4 in which tan δ deviates from the scope of the present invention as shown in Table 2 has a problem in that folding does not occur because stress is not solved during folding.

Simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (21)

The ratio of tan δ at 25 ° C. of Formula 1 is 1 to 2, the ratio of tan δ at −20 ° C. of Formula 2 is 0.1 to 1.5,
An adhesive film formed of an adhesive composition containing a monomer mixture containing a (meth) acrylic acid ester having a hydroxyl group,
<Equation 1>
Ratio of tan δ at 25 ° C. = ([tan δ] 100/25 _{° C.} ) / ([tan δ] 1/25 _{° C.} )
(In Formula 1, [tan δ] 1/25 ° C is tan δ, at 1rad / sec and 25 ° _C of the adhesive film,
[tan δ] 100/25 ° C. is tan δ at 100 rad / sec and 25 ° _C. of the adhesive film)
<Equation 2>
Ratio of tan δ at -20 ° C = ([tan δ] _{100 / -20 ° C} ) / ([tan δ] _{1 / -20 ° C} )
(In Formula 2, [tan δ] _{1 / -20 ℃} is tan δ, at 1rad / sec and -20 ℃ of the adhesive film,
[tan δ] _{100 / -20 ° C.} is tan δ at ₁₀₀ rad / sec and −20 ° _C. of the adhesive film),
The monomer mixture comprises 10% to 25% by weight of (meth) acrylic acid ester having the hydroxyl group and 75% to 90% by weight of (meth) acrylic acid ester having an alkyl group,
The adhesive film is an adhesive modulus of 20 to 70 kPa storage modulus at 100rad / sec at 25 ℃.
The pressure-sensitive adhesive film of claim 1, wherein the pressure-sensitive adhesive composition further comprises an initiator.
The pressure-sensitive adhesive film of claim 1, wherein the (meth) acrylic acid ester having a hydroxyl group comprises a (meth) acrylic acid ester having a hydroxyl group having a glass transition temperature of the homopolymer of -100 ° C to 0 ° C.
The pressure-sensitive adhesive film of claim 1, wherein the (meth) acrylic acid ester having a hydroxyl group comprises at least one of (meth) acrylic acid esters having an alkyl group having 4 to 20 carbon atoms having at least one hydroxyl group.
delete The pressure-sensitive adhesive film of claim 1, wherein the pressure-sensitive adhesive film has a tan δ of 0.3 to 0.7 at 1 rad / sec at −20 ° C. and a storage modulus of 50 kPa to 100 kPa.
The pressure-sensitive adhesive film of claim 1, wherein the pressure-sensitive adhesive film has a tan δ of 0.1 to 0.75 and a storage modulus of 200 kPa to 1000 kPa at 100 rad / sec at -20 ° C.
The pressure-sensitive adhesive film of claim 1, wherein the pressure-sensitive adhesive film further includes organic nanoparticles.
The pressure-sensitive adhesive film of claim 8, wherein the organic nanoparticles have an average particle diameter of 10 nm to 400 nm.
The adhesive film of claim 8, wherein the organic nanoparticles are core-shell particles.
The adhesive film of claim 10, wherein the core and the shell satisfy the following Equation 6:
<Equation 6>
Tg (c) <Tg (s)
(In Formula 6, Tg (c) is the glass transition temperature (unit: ° C) of the core, Tg (s) is the glass transition temperature (unit: ° C) of the shell).
The pressure-sensitive adhesive film of claim 8, wherein the organic nanoparticles are included in an amount of 0.1 to 20 parts by weight based on 100 parts by weight of the monomer mixture.
The pressure-sensitive adhesive film of claim 10, wherein the core is formed of at least one of polybutyl acrylate and polysiloxane, and the shell is polymethyl methacrylate.
The pressure-sensitive adhesive film of claim 2, wherein the pressure-sensitive adhesive composition further comprises at least one of a crosslinking agent and a silane coupling agent.
An optical film, and an adhesive film formed on at least one surface of the optical film,
The adhesive film is to include the adhesive film of claim 1, the optical member.
The optical member according to claim 15, wherein the optical member is a first optical film, a second optical film, and a three-layer film laminate in which the first optical film and the second optical film are laminated by the adhesive film. .
The method of claim 16, wherein the first optical film and the second optical film is one of polyethylene terephthalate resin, polycarbonate resin, polyimide resin, poly (meth) acrylate resin, cyclic olefin polymer resin, acrylic resin Optical member which is a film formed from the above resin.
The optical member of claim 16, wherein each of the first optical film and the second optical film has a thickness of 10 μm to 100 μm, and the adhesive film has a thickness of 10 μm to 100 μm.
The optical member of claim 16, wherein the optical member is for a window film.
An optical display device comprising the adhesive film of claim 1.
The optical member according to any one of claims 15 to 19; And a window coating layer formed on the optical member.

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