KR20160053788A

KR20160053788A - Flexible display apparatus

Info

Publication number: KR20160053788A
Application number: KR1020150150670A
Authority: KR
Inventors: 문형랑; 김지호; 김일진; 곽병도; 김지희; 문성현; 신선희; 이광환; 이우진; 이은화; 조익환; 한재현
Original assignee: 삼성에스디아이 주식회사; 삼성전자주식회사
Priority date: 2014-11-01
Filing date: 2015-10-29
Publication date: 2016-05-13
Also published as: KR101659239B1

Abstract

The flexible display device of the present invention includes an optical element portion; A first adhesive film formed on the optical element; A touch function unit formed on the first adhesive film; A second adhesive film formed on the touch functional part; And a window film formed on the second adhesive film, wherein the first adhesive film or the second adhesive film has a distribution of storage modulus according to a temperature at which the temperature is x-axis (° C) and the storage modulus is y-axis (KPa) Has an average slope of -9.9 to 0 at -20 캜 to 80 캜 with respect to the x-axis, and the storage modulus of the first adhesive film or the second adhesive film at 80 캜 is 10 KPa or more.

Description

[0001] FLEXIBLE DISPLAY APPARATUS [0002]

The present invention relates to a flexible display device.

2. Description of the Related Art In recent years, a flexible display device capable of being folded and unfolded while replacing a glass substrate or a high hardness substrate with a film in a liquid crystal display device, an organic light emitting diode display device, or the like has been developed. The flexible display device has advantages of being thin and light as well as being strong against impacts, being foldable and unfolded by using a film as a substrate, and being able to be manufactured in various forms.

A flexible display device has a structure in which a window film is laminated on a display member, and an optical clear adhesive (OCA) film is interposed between the display member and the window film.

In recent years, the use environment, the storage environment and / or the manufacturing environment of the optical display device have become severer, and as the interest in flexible optical display devices has increased, various properties are required. In particular, for use in a flexible display, an OCA film having excellent viscoelastic characteristics and excellent recovery characteristics in a wide temperature range is required.

The background art of the present invention is disclosed in Japanese Patent Application Laid-Open No. 2007-176542.

An object of the present invention is to provide a flexible display device having excellent quality by applying an adhesive film which maintains viscoelastic characteristics and also has excellent recovery characteristics.

Another object of the present invention is to provide a flexible display device capable of maintaining excellent reliability and durability even in severe use environments, storage environments, and / or manufacturing environments.

The above and other objects of the present invention can be achieved by the present invention described below.

An aspect of the present invention relates to a flexible display device.

In a specific example, the flexible display device includes an optical element, a first adhesive film formed on the optical element, a touch function part formed on the first adhesive film, a second adhesive film formed on the touch functional part, Wherein the first adhesive film or the second adhesive film has a distribution of storage modulus according to a temperature at which the temperature is in the x-axis (° C) and the storage modulus is in the y-axis (KPa) And the average slope at -20 캜 to 80 캜 is -9.9 to 0, and the storage modulus of the first adhesive film or the second adhesive film at 80 캜 may be 10 KPa or more.

In another embodiment, the flexible display device includes an optical element, a first adhesive film formed on the optical element, a touch function formed on the first adhesive film, a second adhesive film formed on the touch functional part, Wherein the first adhesive film or the second adhesive film is formed of a pressure sensitive adhesive composition comprising a monomer mixture and organic particles forming a (meth) acrylic copolymer having a hydroxyl group, and the organic The average particle size of the particles may be between 10 nm and 400 nm.

In another embodiment, the flexible display device may further include a polarizer formed on the touch function unit or the first adhesive film.

In another embodiment, the touch function portion comprises a substrate layer, and the substrate layer may comprise a polarizer.

The optical device may be an OLED, an LED, or an LCD including a light source.

In an embodiment, the thickness of the first adhesive film may be thicker than that of the second adhesive film.

The first adhesive film or the second adhesive film may have a T-peel peel strength at 25 ° C of from 400 gf / in to 5,000 gf / in for a corona-treated polyethylene terephthalate (PET) film.

The first adhesive film or the second adhesive film may have a T-peel peel strength at 60 DEG C of from 200 gf / in to 3,000 gf / in for a corona-treated polyethylene terephthalate (PET) film.

The storage modulus of the first adhesive film or the second adhesive film at 80 ° C may be 10 KPa to 1000 KPa.

The storage modulus of the first adhesive film or the second adhesive film may be 10 KPa to 1000 KPa at -20 캜.

The first adhesive film or the second adhesive film may have a haze of 5% or less after 200% stretching at a thickness of 100 탆.

The first adhesive film or the second adhesive film may have a recovery power of 30% to 98% according to the following formula 1 at a thickness of 100 m.

[Formula 1]

Recovery power (%) = (1- (X _f / X ₀ )) x 100

(Both sides of a PET (polyethylene terephthalate) film (thickness: 75 占 퐉) of a width × length (50 mm × 20 mm) in the above formula 1 is referred to as a first end portion and a second end portion, (20 mm x 20 mm) of the PET film / second end portion of the PET film (20 mm x 20 mm), and the second end portion / And the other jig was pulled at a speed of 300 mm / min to obtain a thickness of the pressure-sensitive adhesive film (unit: (10 times the thickness, X ₀ ) of 10% of the thickness of the adhesive film (10 mm thickness) and then held for 10 seconds and restored to the same speed as the pulling speed (300 mm / min) to apply a force of 0 kPa The length of the stretched adhesive film is X _f (unit: 탆)).

The first adhesive film or the second adhesive film may have an elongation of 800% to 2000%.

On one side of the first adhesive film (13 cm 占 3 cm, thickness 100 占 퐉) or the second adhesive film (13 cm 占 3 cm, thickness 100 占 퐉), 50 占 퐉 thick PET and 100 占 퐉 thick Of PET was laminated in a direction of 50 占 퐉 PET so that the transverse length of the adhesive film was 1/2 between 1 cm of parallel frames, aging was carried out at a temperature of 70 占 폚 and a humidity of 93% for 24 hours, In one case, the bubble generation area may be 0%.

The window film of the flexible display device was replaced with a PET film (thickness: 100 탆), bent in the direction of the PET film between parallel frames spaced by 1 cm, aged at a temperature of 70 캜 and a humidity of 93% for 24 hours, The bubbling area of the first adhesive film or the second adhesive film may be 0%.

The first adhesive film or the second adhesive film is a cured product of the pressure-sensitive adhesive composition, and the pressure-sensitive adhesive composition may include a monomer mixture forming a (meth) acrylic copolymer having a hydroxyl group and organic particles.

The organic particles may have an average particle diameter of 10 nm to 400 nm.

The monomer mixture forming the (meth) acrylic copolymer having a hydroxyl group may include a (meth) acrylate having a hydroxyl group and a comonomer.

The organic particles may have a core-shell structure, and the glass transition temperature of the core and the shell may satisfy the following formula (2).

[Formula 2]

Tg (c) < Tg (s)

Tg (c) is the glass transition temperature (占 폚) of the core, and Tg (s) is the glass transition temperature (占 폚) of the shell.

The glass transition temperature of the core may be -150 ° C to 10 ° C, and the glass transition temperature of the shell may be 15 ° C to 150 ° C.

Wherein the core comprises at least one polyalkyl (meth) acrylate having a glass transition temperature of -150 캜 to 10 캜, and the shell is a polyalkyl (meth) acrylate having a glass transition temperature of 15 캜 to 150 캜 Or more.

In another embodiment, the core or shell comprises two or more layers, and the outermost layer of the organic particles may include one or more polyalkyl (meth) acrylates having a glass transition temperature of 15 ° C to 150 ° C.

The shell may comprise 1 wt% to 70 wt% of the organic particles.

The organic particles may be contained in an amount of 0.1 to 15 parts by weight based on 100 parts by weight of the monomer mixture forming the (meth) acrylic copolymer having a hydroxyl group.

The difference in refractive index between the organic particles and the (meth) acrylic copolymer having a hydroxyl group formed from the monomer mixture may be 0.05 or less.

The (meth) acrylic copolymer having a hydroxyl group may be polymerized from a monomer mixture containing 5 to 40% by weight of a (meth) acrylate having a hydroxyl group and 60 to 95% by weight of a comonomer.

The comonomer may be selected from the group consisting of alkyl (meth) acrylate monomers, monomers having ethylene oxide, monomers having propylene oxide, monomers having amine groups, monomers having amide groups, monomers having alkoxy groups, monomers having phosphoric acid groups, A monomer having a phenyl group and a monomer having a silane group, and the glass transition temperature (Tg) of the comonomer may be -150 ° C to 0 ° C.

In another embodiment, the pressure sensitive adhesive composition may further comprise at least one of an initiator and a crosslinking agent.

INDUSTRIAL APPLICABILITY The present invention provides a flexible display device which can maintain excellent reliability and durability even when the environment for use, the storage environment and / or the manufacturing environment is harsh by applying an adhesive film having excellent viscoelastic characteristics and excellent recovery characteristics, .

1 is a cross-sectional view of a flexible display device according to a specific embodiment of the present invention.
2 is a cross-sectional view of a flexible display device according to another embodiment of the present invention.
3 is a cross-sectional view of a flexible display device according to another embodiment of the present invention.
4 is a conceptual diagram of a specimen for measuring a peel strength of a T-peel.
5 is a sectional view and a plan view of a specimen for recovery force measurement.

The present invention is not limited to the above embodiments and various changes and modifications may be made by those skilled in the art without departing from the scope of the present invention. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification.

The terms "upper" and "lower" in this specification are defined with reference to the drawings, Quot; or "on" may include not only superimposition but also interposition of another structure in the middle. On the other hand, what is referred to as "directly on" or "directly above"

As used herein, "(meth) acryl" means acryl and / or methacryl.

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

As used herein, the term "comonomer" is not limited as long as it is a monomer capable of polymerizing with (meth) acrylate having a hydroxyl group and capable of polymerization with (meth) acrylate having a hydroxyl group.

In the present specification, the "glass transition temperature" of a monomer may mean a glass transition temperature measured by DS Instrument's DSC Discovery for a homopolymer of a monomer to be measured. Specifically, the homopolymer of the monomer to be measured was heated to 180 deg. C at a rate of 20 deg. C / min, cooled slowly to -80 deg. C, and then heated to 180 deg. C at a rate of 10 deg. After obtaining the data of the endothermic transition curve, the inflection point of the endothermic transition curve can be determined as the glass transition temperature.

In the present specification, the "bubble generation area of the pressure-sensitive adhesive film" in this specification refers to a pressure-sensitive adhesive film having a thickness of 50 mu m on one side of an adhesive film (13 cm x 3 cm, thickness 100 mu m) Was bent in a PET direction of 50 占 퐉 in such a manner that the transverse length of the adhesive film was 1/2 between 1 cm-wide parallel frames, aged at a temperature of 70 占 폚 and a humidity of 93% for 24 hours, EX-51) was analyzed with Mountech's Mac-view software and the ratio of the size of the bubble to the area occupied by the area was measured (%).

In the present specification, the "bubble generation area of the display device" is obtained by replacing the window film of the flexible display device with a PET film (thickness of 100 mu m), bending it in the direction of the PET film between parallel frames spaced by 1 cm, Images were measured with an optical microscope (Olympus, EX-51) at a humidity of 93% for 24 hours, analyzed by Mountech's Mac-view software, and the ratio of the size of the bubbles to the area occupied by the bubbles was measured Is the value (%).

In the present specification, "average particle diameter" is the particle diameter of organic particles expressed by the Z-average value measured in a water-based organic solvent by Malvern's Zetasizer nano-ZS equipment.

The term " core-shell structure "as used herein may mean a conventional core-shell structure, including structures in which the core or shell has multiple layers, and the" outermost layer " it means.

In the present specification, the "elongation percentage" refers to a value obtained by preparing a sample of an adhesive film having a thickness of 100 m and a size of 5 cm x 5 cm, and then rolling the sample so that the adhesive film is tightly adhered to the TA (TA.XT_Plus Texture Analyzer Refers to the ratio (%) of the length of the instant at which it is broken with respect to the length before stretching in the case of drawing at a speed of 300 mm / min.

In the present specification, "T-peel peel strength" means a value measured by the following methods i) to v).

i) The pressure-sensitive adhesive composition is coated on a PET (polyethylene terephthalate) film subjected to releasing treatment and irradiated with ultraviolet rays at a light quantity of 2000 mJ / cm ² to produce a pressure-sensitive adhesive sheet of a pressure-sensitive adhesive film and a PET film having a thickness of 100 탆.

ii) Prepare a 150 mm × 25 mm × 75 μm (width × length × thickness) PET film with corona treatment (total dose: 156 doses) while discharging at a dose of 78 doses using a corona processor.

(iii) An adhesive film of 100 mm x 25 mm x 100 m (width x length x thickness) was sampled from the adhesive sheet, and the corona-treated surfaces of the PET film were laminated on both sides of the adhesive film sample, to prepare the specimen shown in Fig.

iv) The specimen is autoclaved at a pressure of 3.5 bar at 50 ° C for 1,000 seconds, and the specimen is fixed on a TA.XT_Plus Texture Analyzer (Stable Micro System).

v) Measure the T-peel peel strength by fixing one PET film and pulling the other PET film at a rate of 50 mm / min in TA.XT_Plus Texture Analyzer. (See Fig. 4 (b)).

The term " recovery force "in this specification refers to the case where both end portions of a PET (polyethylene terephthalate) film (thickness: 75 m) of a length and a length (50 mm x 20 mm) are respectively referred to as a first end portion and a second end portion, The end portions of the two PET films were adhered to each other by a longitudinal (20 mm x 20 mm) adhesive film to be adhered in the order of the first end portion / adhesive film of the PET film / the second end portion of the PET film, And the contact area between the adhesive films is measured as a specimen having a width and a length (20 mm x 20 mm). 5A, a jig is fixed to both end portions of the PET film not adhered to the specimen at room temperature (25 DEG C) 10, pull the length (10 times the initial thickness of the adhesive film, X ₀₎ 1000% of: one jig is fixed and the speed of the other jig is 300 mm / min thickness (㎛) of the above adhesive film Sec and the length of the adhesive film stretched when a force of 0 kPa is applied to the adhesive film is restored to the same speed (300 mm / min) as the speed at which the adhesive film is pulled, is X _f (unit: , And the recovery force (%) are values calculated by the following formula 1:

[Formula 1]

Recovery power (%) = (1- (X _f / X ₀ )) x 100

At this time, the initial thickness of the adhesive film may be 20 탆 to 300 탆. Recovery power can be measured with TA.XT_Plus Texture Analyzer (Stable Micro System). The recovery force can be measured at 25 캜 to 80 캜.

Hereinafter, a flexible display device of the present invention will be described with reference to FIG. 1 is a flexible display device according to an embodiment of the present invention.

1, the flexible display device 100 according to the present invention includes a first adhesive film 92 (a) formed on an optical element 91, an optical element 91, a first adhesive film 92 (a) A second adhesive film 92 (b) formed on the touch function unit 93 and a window film 95 formed on the second adhesive film 92 (b) .

The distribution modulus of the first adhesive film 92 (a) or the second adhesive film 92 (b) varies depending on the temperature, the temperature is defined as x axis (° C), the storage modulus is defined as the y axis KPa, , The average slope at -20 캜 to 80 캜 may be -9.9 to 0. The average slope may be specifically -5 to 0, more specifically -2 to 0. In the above range, the pressure-sensitive adhesive film exhibits viscoelastic characteristics over a wide temperature range, has excellent recovery power, and can be used in a flexible display device.

The average slope means an average slope at -20 캜 to 80 캜 when the storage modulus distribution according to the temperature of the adhesive film is represented by the temperature x-axis (° C) and the storage modulus is represented by the y-axis (KPa) 3 < / RTI >

[Formula 3]

Average slope = (Mo (80 ° C) - Mo (-20 ° C)) / (80 - (- 20))

(In the formula 3, Mo (80 deg. C) is the storage modulus at 80 deg. C, Mo (-20 deg. C) is the storage modulus at -20 deg.

The first adhesive film 92 (a) or the second adhesive film 92 (b) may have a storage modulus of at least 10 KPa at 80 ° C. For example, the storage modulus of the first adhesive film 92 (a) or the second adhesive film 92 (b) is preferably 10 KPa to 1000 KPa, more preferably 10 KPa to 800 KPa, Lt; RTI ID = 0.0 > 100 KPa. &Lt; / RTI > Within the above range, elastic properties are exhibited even at a high temperature, and the recovery performance of the adhesive film is excellent.

The first adhesive film 92 (a) or the second adhesive film 92 (b) is subjected to surface treatment, for example, at 150 mJ / cm ² The corona can be subjected to a preprocessing step. For example, the corona pretreatment can be performed by using a corona processor (Now plasma) to treat the surface to be bonded (e.g., PET film) twice while discharging at a dose of 78 dose. no.

The first adhesive film 92 (a) or the second adhesive film 92 (b) has a T-peel peel strength of 100 μm and a corona-treated PET film at room temperature (25 ° C) Can be from 400 gf / in to 5,000 gf / in, specifically from 500 gf / in to 4,000 gf / in, more specifically from 700 gf / in to 3,500 gf / in. Within the above range, the adhesive strength and reliability of the pressure-sensitive adhesive film at room temperature are excellent.

The T-peel peel strength of the first adhesive film 92 (a) or the second adhesive film 92 (b) to a corona-treated PET film at a thickness of 100 占 퐉 at 60 占 폚 was 200 gf / in to 3,000 gf / in, specifically 500 gf / in to 2,000 gf / in, more specifically 500 gf / in to 1,500 gf / in. In the above range, even when the adhesive film at a high temperature has a curvature shape, the adhesive strength and the reliability are excellent.

The T-peel peel strength of the adhesive film is measured as follows. A corona-treated PET film of width × length × thickness (150 mm × 25 mm × 75 μm) on both sides of an adhesive film of 100 mm × 25 mm × 100 μm (width × length × thickness) , Autoclaved at a pressure of 3.5 bar at 50 캜 for 1000 seconds, and fixed on a TA.XT_Plus Texture Analyzer (Stable Micro System). One PET film is fixed at 25 DEG C or 60 DEG C and the other PET film is pulled at a rate of 50 mm / min to measure the peel strength of the T-peel to the PET film. The corona pretreatment of the PET film can be performed twice (total dose: 156 doses) while discharging at a dose of 78 doses using, for example, a corona processor (Now plasma).

The storage modulus of the first adhesive film 92 (a) or the second adhesive film 92 (b) is preferably 10 KPa or more, for example, 10 KPa to 1000 KPa, more preferably 10 KPa to 800 KPa, More specifically from 10 KPa to 100 KPa. Within the above range, elastic properties are exhibited even at a high temperature, and the recovery performance of the adhesive film is excellent.

The storage modulus of the first adhesive film 92 (a) or the second adhesive film 92 (b) is preferably 10 KPa to 1000 KPa, more preferably 10 KPa to 800 KPa, more specifically 20 KPa Lt; RTI ID = 0.0 > 500 KPa. &Lt; / RTI > Within the above range, viscoelastic characteristics are exhibited at room temperature and the recovery power is excellent.

The storage modulus of the first adhesive film 92 (a) or the second adhesive film 92 (b) is preferably 10 KPa to 1000 KPa, more preferably 10 KPa to 500 KPa, more specifically 20 KPa Lt; RTI ID = 0.0 > 500 KPa. &Lt; / RTI > In the above range, when used in a flexible device at a low temperature, there is an advantage that the pressure-sensitive adhesive film is flexible and is not whitened and can be used for an optical material.

The ratio of the storage modulus at 80 ° C to the storage modulus at -20 ° C is in the range of 1: 1 to 1:10, specifically 1: 1 at 80 ° C for the first adhesive film 92 (a) or the second adhesive film 92 (b) 1 to 1: 8, more specifically from 1: 1 to 1: 5. In the above-mentioned range, the adhesive film does not deteriorate the adhesive force between the adherend in a wide temperature range (-20 to 80 ° C) and can be used in a flexible display device.

The first adhesive film 92 (a) or the second adhesive film 92 (b) has a thickness of 100 탆 and an adhesive film having a haze of 5% or less, specifically 3% or less, more specifically 1% . &Lt; / RTI > In the above-mentioned range, when the pressure-sensitive adhesive film is used in an optical display device, it exhibits excellent transparency.

The first adhesive film 92 (a) or the second adhesive film 92 (b) has a haze of not more than 5%, specifically not more than 3%, more specifically not more than 1% % Or less of the adhesive film. In the above range, the pressure-sensitive adhesive film exhibits excellent transparency when used in a display.

The first adhesive film 92 (a) or the second adhesive film 92 (b) has a recovery force of 30% to 98%, for example, 40% to 95% Lt; / RTI > In the above-mentioned range, the pressure-sensitive adhesive film can be applied to a flexible display device, and the lifetime is also increased.

[Formula 1]

Recovery power (%) = (1- (X _f / X ₀ )) x 100

The first adhesive film 92 (a) or the second adhesive film 92 (b) was cut to have a thickness of 100 m and a size of 5 cm x 5 cm and then rolled so as to be closely contacted with each other to obtain a TA (TA.XT_Plus Texture Analyzer When the ends of the adhesive film are stretched at a speed of 300 mm / min, the length of the moment when the adhesive film is cut off is 800% to 2000%, specifically 800% To 1800%, and more specifically, from 900% to 1700%. The above-described range is applicable to a flexible display device and is excellent in reliability.

The first adhesive film 92 (a) or the second adhesive film 92 (b) is a PET film having a size of 13 cm x 3 cm and a thickness of 100 m and having a thickness of 50 m on one surface of a pressure- The adhesive film laminated with PET having a thickness of 100 mu m was bent in a PET direction of 50 mu m so that the transverse length of the adhesive film was 1/2 between parallel frames spaced by 1 cm, aged at a temperature of 70 DEG C and a humidity of 93% for 24 hours the agglomeration area may be 0%. In the above range, the pressure-sensitive adhesive film is excellent in reliability and can be applied to a flexible display device.

The flexible display device 100 was manufactured by replacing a window film with a PET film (thickness: 100 μm), bending it in the direction of the PET film between parallel frames spaced by 1 cm, aging at a temperature of 70 ° C. and a humidity of 93% the bubbling area of the first adhesive film or the second adhesive film may be 0%. Within the above-mentioned range, bubbles can be recovered by reducing the bubble area by spreading, spreading, and moving, and reliability of the pressure-sensitive adhesive film and display device is increased.

The first adhesive film 92 (a) or the second adhesive film 92 (b) may have a thickness of 1 to 2 mm, specifically 50 to 1 mm, and in this range, .

The first adhesive film 92 (a) or the second adhesive film 92 (b) may be formed by curing the pressure-sensitive adhesive composition. Alternatively, the first adhesive film 92 (a) or the second adhesive film 92 (b) may include a cured product of the pressure-sensitive adhesive composition.

The pressure-sensitive adhesive composition may include a monomer mixture and organic particles forming a (meth) acrylic copolymer having a hydroxyl group.

The monomer mixture forming the (meth) acrylic copolymer having a hydroxyl group may include a (meth) acrylate having a hydroxyl group and a comonomer, and the (meth) acrylic copolymer having the hydroxyl group may be prepared by polymerizing the monomer mixture .

The (meth) acrylate having a hydroxyl group is preferably a (meth) acrylic acid ester having an alkyl group of 1-20 carbon atoms having at least one hydroxyl group, a (meth) acrylic ester having a cycloalkyl group having 5-20 carbon atoms having at least one hydroxyl group, Or a (meth) acrylic acid ester having an aryl group having 6 to 20 carbon atoms and having at least one hydroxyl group.

Examples of the (meth) acrylate having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (Meth) acrylate, propyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 6-hydroxyhexyl (meth) acrylate. In particular, by using a (meth) acrylic monomer containing an alkyl group having 1 to 5 carbon atoms and having a hydroxyl group, an adhesive strength increasing effect can be further obtained.

The (meth) acrylate having a hydroxyl group may be contained in an amount of 5 to 40% by weight, for example, 10 to 30% by weight in the monomer mixture forming the (meth) acrylic copolymer having a hydroxyl group. In the above range, the pressure-sensitive adhesive film has an excellent adhesive strength and reliability.

The comonomer is at least one selected from the group consisting of alkyl (meth) acrylate monomers, monomers having ethylene oxide, monomers having propylene oxide, monomers having amine groups, monomers having amide groups, monomers having alkoxy groups, monomers having phosphoric acid groups, And monomers having a silane group. However, the present invention is not limited thereto.

The alkyl (meth) acrylate monomer may include unsubstituted linear or branched alkyl (meth) acrylates having 1 to 20 carbon atoms. (Meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, (Meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, ethylhexyl (meth) acrylate, octyl Acrylate, decyl (meth) acrylate, and lauryl (meth) acrylate. Specifically, by using an alkyl (meth) acryl monomer having 4 to 8 carbon atoms, the effect of increasing the initial adhesive strength may be further increased.

As the monomer having an ethylene oxide, one or more (meth) acrylate monomers containing an ethylene oxide group (-CH ₂ CH ₂ O-) may be used. (Meth) acrylate, polyethylene oxide monoethyl ether (meth) acrylate, polyethylene oxide monopropyl ether (meth) acrylate, polyethylene oxide monobutyl ether (meth) acrylate, polyethylene oxide mono (Meth) acrylate, polyethylene oxide monoisobutyl ether (meth) acrylate, polyethylene oxide diethyl ether (meth) acrylate, polyethylene oxide monoisopropyl ether (meth) acrylate, polyethylene oxide monoisobutyl ether (Meth) acrylate such as polyethylene oxide mono-t-butyl ether (meth) acrylate, but is not limited thereto.

The monomer having propylene oxide may be at least one selected from the group consisting of 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 diethyl ether (meth) acrylate, polypropylene oxide monoisopropyl ether (meth) acrylate, polypropylene oxide monoethyl ether (Meth) acrylate such as polyoxyethylene (meth) acrylate, polypropylene oxide monoisobutyl ether (meth) acrylate, and polypropylene oxide mono butyl ether (meth) acrylate. Thing no.

Examples of the monomer having an amino group include monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate, monoethylaminopropyl (meth) acrylate, dimethylaminoethyl (Meth) acrylate containing an amino group such as (meth) acrylate, diethylaminoethyl (meth) acrylate, N-tert-butylaminoethyl (meth) acrylate and methacryloxyethyltrimethylammonium chloride But are not necessarily limited to, monomers.

The amide group-containing monomer may be at least one monomer selected from the group consisting of (meth) acrylamide, N-methyl acrylamide, N-methyl methacrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (Meth) acrylic monomer including amide group such as methylene bis (meth) acrylamide and 2-hydroxyethyl acrylamide, but is not limited thereto.

The monomer having an alkoxy group may be at least one monomer selected from the group consisting of 2-methoxyethyl (meth) acrylate, 2-methoxypropyl (meth) acrylate, 2-ethoxypropyl (meth) (Meth) acrylate, 2-methoxypentyl (meth) acrylate, 2-ethoxypentyl (meth) acrylate, 2-butoxyhexyl (Meth) acrylate, 3-butoxyhexyl (meth) acrylate, and the like.

Examples of the monomer having a phosphate group include 2-methacryloyloxyethyldiphenyl phosphate (meth) acrylate, trimethacryloyloxyethyl phosphate (meth) acrylate, triacryloyloxyethyl phosphate (meth) acrylate , And the like, but the present invention is not limited thereto.

The monomer having a sulfonic acid group is preferably an acrylic monomer having a sulfonic acid group such as sodium sulfopropyl (meth) acrylate, sodium 2-sulfoethyl (meth) acrylate and sodium 2-acrylamido- But is not necessarily limited thereto.

The monomer having a phenyl group can be an acrylic vinyl monomer having a phenyl group such as p-tert-butylphenyl (meth) acrylate or o-biphenyl (meth) acrylate, but is not limited thereto.

The monomer having a silane group may be at least one selected from the group consisting of 2-acetoacetoxyethyl (meth) acrylate, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (beta -methoxyethyl) silane, vinyltriacetylsilane, Propyltrimethoxysilane, and the like, but is not limited thereto.

The comonomer may comprise from 60% to 95% by weight, such as from 70% by weight to 90% by weight, of the monomer mixture forming the (meth) acrylic copolymer having a hydroxyl group. In the above range, the pressure-sensitive adhesive film has an excellent adhesive strength and excellent reliability.

In another embodiment, the comonomer having a glass transition temperature (Tg) of -150 ° C to 0 ° C may be used. Here, the glass transition temperature can be measured, for example, by using DSC Discovery of TA Instrument for a homopolymer of each monomer to be measured. Specifically, the homopolymer of each monomer was heated to 180 ° C at a rate of 20 ° C / minute, gradually cooled to -80 ° C, and then heated to 180 ° C at a rate of 10 ° C / After obtaining the data of the transition curve, the inflection point of the endothermic transition curve is determined as the glass transition temperature. The comonomer having a glass transition temperature (Tg) of -150 ° C to 0 ° C can be used without limitation as long as it has a glass transition temperature (Tg) of -150 ° C to 0 ° C. Specifically, a comonomer having a glass transition temperature (Tg) of -150 ° C. to -20 ° C., more specifically, a comonomer having a glass transition temperature (Tg) of -150 ° C. to -40 ° C. can be used.

In another embodiment, the comonomer is selected from the group consisting of alkyl (meth) acrylate monomers, monomers with ethylene oxide, monomers with propylene oxide, monomers with amine groups, monomers with amide groups, monomers with alkoxy groups, One or more monomers having a sulfonic acid group, a monomer having a phenyl group and a monomer having a silane group and having a glass transition temperature (Tg) of -150 ° C to 0 ° C may be used.

Such comonomers include, for example, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, hexyl (meth) acrylate, Alkyl (meth) acrylate monomers including hexyl acrylate, dodecyl (meth) acrylate and the like; (Meth) acrylate, polyethylene oxide monoethyl ether (meth) acrylate, polyethylene oxide monoethyl ether (meth) acrylate, polyethylene oxide monopropyl ether (meth) acrylate, polyethylene oxide monobutyl ether (Meth) acrylate, polypropylene oxide monomethyl ether (meth) acrylate, polypropylene oxide monoethyl ether (meth) acrylate, and polypropylene oxide monopropyl ether (meth) Meth) acrylate monomers; (Meth) acrylate having an amino group including monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate and monoethylaminopropyl (meth) Rate monomers; (Meth) acrylate monomers having an alkoxy group including 2-methoxyethyl (meth) acrylate, 2-methoxypropyl (meth) acrylate, 2-ethoxypropyl (meth) acrylate and the like; (Meth) acrylate monomer having a silane group including 2-acetoacetoxyethyl (meth) acrylate, vinyltrimethoxysilane, vinyltriethoxysilane, and the like.

In embodiments, the monomer mixture may comprise (meth) acrylate monomers having a hydroxyl group and comonomers having a glass transition temperature (Tg) between -150 ° C and 0 ° C. In this case, the comonomer having a glass transition temperature (Tg) of -150 ° C to 0 ° C in the monomer mixture may be contained in an amount of 60 to 95% by weight, for example, 70 to 90% by weight, There is an excellent effect of reliability. The (meth) acrylate having a hydroxyl group may be contained in the monomer mixture in an amount of 5 to 40% by weight, for example, 10 to 30% by weight. In the above range, the haze is low and the adhesive strength is excellent.

In an embodiment, the monomer mixture may further comprise a monomer having a carboxyl group.

The monomer having a carboxyl group is at least one monomer selected from the group consisting of (meth) acrylic acid, 2-carboxyethyl (meth) acrylate, 3-carboxypropyl (meth) acrylate, 4-carboxybutyl (meth) acrylate, itaconic acid, Fumaric acid, maleic anhydride, and the like, but are not limited thereto.

For example, the monomer having a carboxyl group may further include not more than 10% by weight, specifically not more than 5% by weight, more specifically not more than 1% by weight, of the total monomer mixture. In this range, the adhesive strength is high and the reliability is excellent.

Since the pressure-sensitive adhesive composition or the pressure-sensitive adhesive film contains organic particles, the pressure-sensitive adhesive composition or the pressure-sensitive adhesive film is excellent in low temperature and / or room temperature viscoelasticity, has a crosslinked structure, and stably exhibits high temperature viscoelasticity. In an embodiment, the organic particles may form a chemical bond with the (meth) acrylic copolymer having a hydroxyl group.

Specifically, although the pressure-sensitive adhesive composition or the pressure-sensitive adhesive film contains the organic particles, it has a specific refractive index difference between the following specific average particle size organic particles and the following (meth) acrylic copolymer having a hydroxyl group, .

The organic particles 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. Within the above range, aggregation of organic particles can be prevented, and transparency is excellent.

The difference in refractive index between the organic particles and the (meth) acrylic copolymer having a hydroxyl group may be 0.05 or less, specifically 0 or more and 0.03 or less, and more specifically 0 or more and 0.02 or less. Within the above range, the transparency of the adhesive film is excellent.

[Formula 2]

Tg (c) < Tg (s)

(C) is the glass transition temperature (占 폚) of the core, and Tg (s) is the glass transition temperature (占 폚) of the shell)

Specifically, the glass transition temperature of the core may be -150 ° C to 10 ° C, specifically -150 ° C to -5 ° C, more specifically -150 ° C to -20 ° C. It is possible to realize a storage modulus value required at a low temperature (-20 DEG C) in the above range, and is excellent in low temperature and / or room temperature viscoelastic properties.

Specifically, the core may contain at least one polyalkyl (meth) acrylate having a glass transition temperature as described above. For example, the core may be selected from the group consisting of polymethyl acrylate, polyethylacrylate, polypropyl acrylate, polybutyl acrylate, polyisopropyl acrylate, polyhexyl acrylate, polyhexyl methacrylate, polyethylhexyl acrylate, And polyethylhexyl methacrylate, but is not limited thereto. For example, one or more of polybutyl acrylate and polyethylhexyl acrylate.

The glass transition temperature of the shell may be from 15 캜 to 150 캜, specifically from 35 캜 to 150 캜, more specifically from 50 캜 to 140 캜. There is an advantage that the dispersibility of the organic particles is excellent in the (meth) acrylic copolymer having a hydroxyl group within the above range.

Specifically, the shell may comprise a polyalkyl (meth) acrylate having a glass transition temperature as described above. For example, it is possible to use polymethylmethacrylate (PMMA), polyethylmethacrylate, polypropylmethacrylate, polybutylmethacrylate, polyisopropylmethacrylate, polyisobutylmethacrylate and polycyclohexylmethacrylate Rate, < / RTI > but is not necessarily limited thereto. For example, polymethyl methacrylate.

In another embodiment, the core or shell comprises two or more layers, and the outermost layer of the organic particles may comprise at least one polyalkyl (meth) acrylate having a glass transition temperature of 15 ° C to 150 ° C . Specifically, the core may comprise at least one polyalkyl (meth) acrylate having a glass transition temperature of -150 캜 to 10 캜, and may contain at least one polyalkyl (meth) acrylate , The glass transition temperature of the whole core may satisfy -150 캜 to 10 캜, but is not necessarily limited thereto. The shell may also contain at least one polyalkyl (meth) acrylate having a glass transition temperature of 15 ° C to 150 ° C, and may contain at least one polyalkyl (meth) acrylate without limitation of glass transition temperature, The glass transition temperature of the whole may satisfy 15 deg. C to 150 deg. C and is not necessarily limited thereto.

The shell may contain 1 wt% to 70 wt%, specifically 5 wt% to 60 wt%, and more specifically 10 wt% to 50 wt% of the organic particles. Within the above-mentioned range, the viscoelastic characteristics are maintained in a wide temperature range, and the recovery ability of the adhesive film is excellent.

The organic particles are added in an amount of 0.1 to 15 parts by weight, specifically 0.1 to 10 parts by weight, more specifically 0.1 to 8 parts by weight, based on 100 parts by weight of the monomer mixture forming the (meth) acrylic copolymer having a hydroxyl group 8 parts by weight. There is an effect of having good adhesion and reliability in the above range.

In one embodiment, the (meth) acrylic copolymer having a hydroxyl group comprises 5 to 40% by weight, specifically 10 to 30% by weight of a (meth) acrylate having a hydroxyl group and a comonomer (for example, From 60% by weight to 95% by weight, specifically from 70% by weight to 90% by weight, of a comonomer having a temperature (Tg) of -150 ° C to 0 ° C). There is an effect of having good adhesion and reliability in the above range.

In another embodiment, the (meth) acrylic copolymer having a hydroxyl group is a copolymer of 5 to 40% by weight, for example 10 to 30% by weight, of a (meth) acrylate having a hydroxyl group, For example, from 70% by weight to 90% by weight, from 0% by weight to 10% by weight, for example from 0.1% by weight, of a monomer having a carboxyl group, % &Lt; / RTI > to 1% by weight, based on the total weight of the composition. There is an effect of having good adhesion and reliability in the above range.

In one embodiment, the organic particles contained in the pressure-sensitive adhesive composition may be polymerized with the monomer mixture to form a (meth) acrylic copolymer having a hydroxyl group. In the preparation of the (meth) acrylic copolymer having a hydroxyl group, the organic particles may be used in a polymerized state together with the monomer mixture. In this case, the organic particles may be used in a state contained in a (meth) acrylic copolymer having a hydroxyl group.

In another embodiment, the pressure sensitive adhesive composition may comprise organic particles with a (meth) acrylic copolymer having a hydroxyl group already polymerized from the monomer mixture. In this case, the organic particles may be contained in the pressure-sensitive adhesive composition separately from the (meth) acrylic copolymer having a hydroxyl group.

The glass transition temperature of the (meth) acryl-based copolymer having a hydroxyl group may be -150 ° C to -13 ° C, specifically -100 ° C to -20 ° C. In this range, There is an effect of having good adhesion and reliability.

The (meth) acrylic copolymer having a hydroxyl group can be specifically prepared by mixing a monomer mixture and an organic particle with a radical photopolymerization initiator, followed by solution polymerization, suspension polymerization, photopolymerization, bulk polymerization, dispersion polymerization or emulsion polymerization. Or a monomer mixture is partially polymerized to prepare a prepolymer, and then organic particles are added to the prepolymer to prepare a (meth) acrylic copolymer having a hydroxyl group. Specifically, emulsion polymerization can be carried out at 25 ° C to 100 ° C by adding an initiator to a dispersant, a crosslinking agent and a monomer mixture and an organic particle in an aqueous solution.

In an embodiment, the pressure-sensitive adhesive composition may further comprise at least one of a crosslinking agent and an initiator.

The crosslinking agent may be a polyfunctional (meth) acrylate such as 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) (Meth) acrylate, neopentylglycol adipate di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylate, (Meth) acrylate, di (meth) acryloxyethyl isocyanurate, allyl cyclohexyl di (meth) acrylate, tricyclodecane dimethanol (meth) acrylate, (Meth) acrylate, ethylene oxide modified hexahydrophthalic acid di (meth) acrylate, tricyclodecane dimethanol (meth) acrylate, neopentyl glycol modified trimethylene Acrylate such as 2-ethylhexyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl acrylate, Rate; (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) acryloxyethylisocyanurate; Tetrafunctional acrylates such as diglycerin tetra (meth) acrylate or pentaerythritol tetra (meth) acrylate; Pentafunctional acrylates such as dipentaerythritol penta (meth) acrylate; (Meth) acrylate, dipentaerythritol hexa (meth) acrylate, caprolactone modified dipentaerythritol hexa (meth) acrylate or urethane (meth) acrylate (ex. Isocyanate monomer and trimethylol propane tri And a hexafunctional acrylate such as a polyfunctional acrylate having a hydroxyl group of 2 to 20. Specifically, the cross-linking agent may be a polyfunctional (meth) acrylate having 2 to 20 hydroxyl groups (Meth) acrylate having an excellent endurance reliability.

The crosslinking agent may be contained in an amount of 0.01 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 forming the (meth) acrylic copolymer having a hydroxyl group have. There is an effect of excellent adhesion and reliability in the above range.

As the initiator, a radical type photopolymerization initiator or a thermal polymerization initiator may be used.

The initiator may be the same as or different from the initiator used in the preparation of the (meth) acrylic copolymer having a hydroxyl group. In another embodiment, a thermal polymerization initiator may be used.

The photopolymerization initiator may be any as long as it can induce polymerization reaction of the radical polymerizing compound described above during the curing process by photoirradiation to realize the second crosslinking structure. For example, benzoin, hydroxy ketone, amino ketone or phosphine oxide photoinitiators can be used. Specific examples thereof include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether , Benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethyl anino acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy- Methyl-1 - [4- (methylthio) phenyl] -2-morpholino-propane-1-one, 1-hydroxycyclohexyl phenyl ketone, (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4-nonocydiethylaminobenzophenone, dichlorobenzophenone, 2 2-ethyl anthraquinone, 2-t-butyl anthraquinone, 2-amino anthraquinone, thioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4- Dimethyl t (2-hydroxy-2-methyl-1- [4- (1-methylvinyl) -1,3-dihydrothiazonato, benzyldimethyl ketal, acetophenone dimethyl ketal, p- Phenyl] propanone] and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide. In the present application, one kind or more kinds of the above can be used, but the present invention is not limited thereto.

The kind of the thermal polymerization initiator is not particularly limited as long as it has the above physical properties, and for example, a conventional initiator such as an azo compound, a peroxide compound or a redox compound can be used. Examples of the azo compound include 2,2-azobis (2-methylbutyronitrile), 2,2-triyl azo bis (isobutyronitrile), 2,2-triazabis 2-methyl azo bis (2-methylpropionate) and 2,2-phylazobis (4- (4-methoxyphenyl) Methoxy-2,4-dimethylvaleronitrile), and the like, and examples of the peroxide compound include inorganic peroxides such as potassium persulfate, ammonium persulfate or hydrogen peroxide; Or peroxydicarbonate, peroxydicarbonate, peroxy ester, tetramethyl butyl peroxyneodecanoate, bis (4-butylcyclohexyl) peroxydicarbonate, di (2-ethylhexyl) peroxycarbonate, Hexyl peroxy dicarbonate, dimethoxy butyl peroxy dicarbonate, hexyl peroxy dicarbonate, hexyl peroxy dicarbonate, diisopropyl peroxy dicarbonate, diethoxy ethyl peroxy dicarbonate, diethoxyhexyl 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 peroxypivalate, butyl peroxypivalate, trimethylhexanoyl peroxide, dimethylhydroxybutyl peroxy Amyl peroxyneodecanoate, t-butyl peroxyneoheptanoate, amyl peroxy pivalate, t-butyl peroxy pivalate, t-amyl peroxide, Organic peroxides such as peroxy-2-ethylhexanoate, lauryl peroxide, dilauroyl peroxide, didecanoyl peroxide, benzoyl peroxide or dibenzoyl peroxide, Examples of the system compound include, but are not limited to, a mixture of a peroxide compound and a reducing agent in combination. In the present application, one kind or a mixture of two or more kinds of azo type, peroxide type or redox type compound as described above can 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 forming the (meth) acrylic copolymer having a hydroxyl group have. In the above range, the curing reaction can be completely carried out, and the remaining amount of the initiator remains, the permeability can be prevented from being lowered, the bubble generation can be lowered, and the reactivity can be improved.

In another embodiment, the pressure sensitive adhesive composition may further comprise a silane coupling agent.

The silane coupling agent may further include a siloxane-based or epoxy-based silane coupling agent, but is not limited thereto. The silane coupling agent may be contained in an amount of 0.01 part by weight to 0.1 part by weight, specifically 0.05 part by weight to 0.1 part by weight, based on 100 parts by weight of the monomer mixture forming the (meth) acrylic copolymer having a hydroxyl group. There is an effect of increasing the reliability in the above range.

The pressure-sensitive adhesive composition may optionally contain a curing accelerator, an ionic liquid, a lithium salt, an inorganic filler, a softener, a molecular weight modifier, an antioxidant, an antioxidant, a stabilizer, a tackifier resin, a modifying resin (polyol resin, phenol resin, (Coloring pigments, extender pigments, etc.), treating agents, ultraviolet light blocking agents, fluorescent whitening agents, dispersing agents, heat stabilizers, antioxidants, antioxidants, A light stabilizer, an ultraviolet absorber, an antistatic agent, a coagulant, a lubricant and a solvent.

The pressure-sensitive adhesive composition may further comprise an uncurable compound.

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

1, the flexible display device 100 according to an embodiment of the present invention including the above-mentioned adhesive film includes a first adhesive film 92 (a (n) formed on an optical element 91, an optical element 91, ), A touch function unit 93 formed on the first adhesive film 92 (a), a second adhesive film 92 (b) formed on the touch function unit 93, and a second adhesive film 92 b)). < / RTI >

The optical element unit 91 may be an LCD including an OLED, an LED, or a light source, for example, as long as it is made of flexible materials. The optical device unit 91 may include a touch function unit 93 on an LCD panel having an OLED, an LED, or a light source, and the touch function unit 93 may be in contact with the polarizer 94. The adhesive film of the present invention may be interposed between the OLED, the LED, or the LCD panel having the light source and the touch function unit 93.

The touch function unit 93 senses an electrical signal due to contact of a finger or the like, and can be formed of a material having flexibility. Specifically, a metal nanowire as a conductive material having flexibility, or a conductor obtained by patterning a conductive film containing a conductive polymer can be used. For example, the touch function unit 93 can form the conductor on a base layer (not shown). The touch function unit 93 can be a conventional one, and is commercially available. The optical element portion 91 can be laminated to the lower portion of the touch function portion 93 via the first adhesive film 92 (a).

The window film 95 can be a conventional one, and is commercially available. In one embodiment, the window film 95 may be formed of an optically transparent and flexible resin, which may consist of a substrate layer and a hard coating layer. Examples of the base layer include polyester resins such as polyethylene terephthalate polyether naphthalate, polybutyl terephthalate and polybutylene naphthalate, polycarbonate resins, polyimide resins, polystyrene resins, polymethylmethacrylate, and the like. (Poly (meth) acrylate). &Lt; / RTI > The hard coating layer has a pencil hardness of 6H or more and may be formed of a siloxane resin.

In one embodiment, the second adhesive film 92 (b) may be made of the same material as the first adhesive film 92 (a). Here, 'the same material' means that the components and properties are the same. In another embodiment, the second adhesive film 92 (b) may be a different material from the first adhesive film 92 (a). In another embodiment, the thickness of the first adhesive film 92 (a) may be thicker than that of the second adhesive film 92 (b). Accordingly, the first adhesive film 92 (a) has a higher adhesive force than the second adhesive film 92 (b), and the reliability of the flexible display device is high and the optical element can be planarized.

2, the flexible display device 200a, 200b may further include a polarizer 94 formed on the touch function part 93 or the first adhesive film 92 (a) . More specifically, the flexible display device 200a may be configured such that the polarizer 94 is formed on the touch function unit 93 and the second adhesive film 92 (refer to FIG. the window film 95 may be laminated via the b). Or the flexible display device 200b may be laminated on the optical element 91 via the first adhesive film 92 (a).

The polarizer 94 polarizes natural light or artificial light. The polarizer 94 may be formed by dyeing iodine or a dichroic dye to a modified polyvinyl alcohol film or polyolefin film such as a partially-porous polyvinyl alcohol film or an acetoacetyl-modified polyvinyl alcohol film, And stretched in a predetermined direction. Specifically, it is produced through a swelling process, a dyeing process, and a stretching process. Methods of performing each step are commonly known to those skilled in the art. The polarizer 94 can be applied to a conventional one, and is commercially available.

3, the touch function portion 93 of the flexible display device 300 is capable of forming the conductor on a base layer, although not shown, and the base layer is made of a polarizer 98 .

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

The contents not described here are sufficiently technically inferior to those skilled in the art, and a description thereof will be omitted.

Example

Production of adhesive film

The composition used for producing the adhesive film is as follows.

(A) a monomer mixture

(a1) 2-ethylhexyl acrylate (EHA) was used.

(a2) 4-hydroxybutyl acrylate (HBA) was used.

(B) an organic particle

(b1) the core is a core-shell structure composed of polybutyl acrylate (PBA) and the shell is polymethyl methacrylate (PMMA), the shell is 40 wt% of the organic particles, the average particle diameter is 230 nm, the refractive index N _B ) was 1.48.

(b2) the core is a core-shell structure composed of polybutyl acrylate (PBA) and the shell is polymethyl methacrylate (PMMA), the shell is 30 wt% of the organic particles, the average particle diameter is 230 nm, the refractive index N _B ) was 1.48.

(b3) the core is a core-shell structure composed of polybutyl acrylate (PBA) and the shell is polymethyl methacrylate (PMMA), the shell is 30 wt% of the organic particles, the average particle diameter is 130 nm, the refractive index N _B ) was 1.48.

(b4) the core is a core-shell structure composed of poly 2-ethylhexyl acrylate (PEHA) and the shell is polymethylmethacrylate (PMMA), the shell is 30 wt% of the organic particles, , And refractive index (N _B ) of 1.48 were used.

(C) Radical polymerization initiator:

(c1) A product of IGACURE 651 (2,2-dimethoxy-2-phenylacetophenone) manufactured by BASF was used.

(c2) IGACURE 184 (1-hydroxycyclohexyl phenyl ketone) product manufactured by BASF was used.

(c3) A product of AIBN ((Azobisisobutyronitrile), Junsei) was used as a thermal polymerization initiator.

Manufacturing example One

4 parts by weight of the organic particles (b1) relative to 100 parts by weight of the mixture of 70% by weight of 2-ethylhexyl acrylate (a1), 30% by weight of 4-hydroxybutyl acrylate (a2), and a photopolymerization initiator (c1) (Irgacure 651 ) Were mixed well in a glass container. The mixture was polymerized by replacing the dissolved oxygen in the glass vessel with nitrogen gas and irradiating with ultraviolet rays using a low-pressure lamp (BL Lamp manufactured by Sankyo) for several minutes to obtain a solution having a viscosity of about 1000 CPS (Meth) acrylic copolymer having a hydroxyl group having a refractive index (N _AB ). 0.35 parts by weight of an additional photopolymerization initiator (c2) (Irgacure 184) was added to the resulting (meth) acrylic copolymer having a hydroxyl group to prepare a pressure-sensitive adhesive composition.

The resulting pressure-sensitive adhesive composition was coated on a polyester film (release film, polyethylene terephthalate film, thickness: 50 mu m) to form an adhesive film having a thickness of 100 mu m. The upper side of the release film was covered with a 75 mu m thick release film and then irradiated with a low-pressure lamp (BL Lamp manufactured by Sankyo Company) for about 6 minutes to obtain a transparent pressure-sensitive adhesive sheet.

Manufacturing example 2 to 7 and 9

A transparent pressure-sensitive adhesive sheet was produced in the same manner as in Production Example 1, except that the content of each component in Production Example 1 was changed as shown in Table 1 below.

Manufacturing example 8

4 parts by weight of organic particles (b3) relative to 100 parts by weight of a mixture of 80% by weight of 2-ethylhexyl acrylate (a1), 20% by weight of 4-hydroxybutyl acrylate (a2), and 10 parts by weight of a thermopolymerization initiator (AIBN (Junsei) And 130 parts by weight of ethyl acetate relative to 100 parts by weight of the monomer and the organic particle mixture were put in a glass container and mixed well. The dissolved oxygen in the glass container was replaced with nitrogen gas and subjected to ordinary solution polymerization at 65 ° C to obtain a (meth) acrylic copolymer having a hydroxyl group having the refractive index (N _AB ) shown in Table 1 below. An additional photopolymerization initiator (c2) IRGACURE 184 (0.35 parts by weight) was added to the resulting (meth) acrylic copolymer having a hydroxyl group to prepare a pressure-sensitive adhesive composition.

Thereafter, a transparent pressure-sensitive adhesive sheet was prepared in the same manner as in Production Example 1, and hot air drying was further performed at 80 ° C for 20 minutes and at 100 ° C for 5 minutes.

The properties of the transparent pressure-sensitive adhesive sheets prepared in Production Examples 1 to 9 were evaluated in the following Table 1, and the results are shown in Table 1 below.

Property evaluation method

(1) Storage modulus: The viscoelasticity was measured by ARES (Anton Paar MCR-501), a dynamic viscoelasticity measuring device, at a shear rate of 1 rad / sec and strain 1% under an auto strain condition. After removing the release film, the adhesive film was laminated to a thickness of 500 탆, and the laminate was punctured with a perforator having a diameter of 8 mm and used as a specimen. The measurement was carried out at a temperature rise rate of 5 DEG C / min in a temperature range of -60 DEG C to 90 DEG C using an 8 mm jig, and the elastic modulus was recorded at -20 DEG C, 25 DEG C and 80 DEG C.

(2) Average slope: When the storage modulus distribution according to the temperature of the adhesive film is represented by the temperature x axis (占 폚) and the storage modulus is represented by the y axis (KPa), the average slope at- Respectively.

[Formula 3]

Average slope = (Mo (80 ° C) - Mo (-20 ° C)) / (80 - (- 20))

(3) T-peel peeling strength: The corona was treated twice with a width × length × thickness (150 mm × 25 mm × 75 μm) PET film while discharging at a dose of 78 dose using a corona processor : 156 dose). Adhesive film samples were obtained from the pressure-sensitive adhesive sheets of Examples and Comparative Examples in a size of 100 mm x 25 mm x 100 m (width x length x thickness). The corona-treated surfaces of the PET film were laminated on both sides of the adhesive film sample to prepare the specimen shown in Fig. 4 (a). The specimen was autoclaved at a pressure of 3.5 bar at 50 ° C for 1000 seconds and the specimens were fixed on a TA.XT_Plus Texture Analyzer (Stable Micro System). Referring to FIG. 4 (b), one PET film was fixed at 25 ° C. using a TA.XT_Plus Texture Analyzer and the other PET film was pulled at a rate of 50 mm / min to remove the T-peel at 25 ° C. The strength was measured. (See Fig. 4 (b)).

The T-Peel peel strength at 60 ° C was measured by using a TA.XT_Plus Texture Analyzer to fix one PET film at 60 ° C and pull the other PET film at a rate of 50 mm / min.

(4) Haze: Haze meter (model Nippon Denshoku Model NDH 5000) was used. According to the American Society for Testing and Measurement (ASTM) Test Method D 1003-95 ("Standard Test for Haze and Luminous Transmittance of Transparent Plastic"), The haze was measured.

(5) Haze after 200% stretching: Both ends of a sample (5 cm x 5 cm, thickness 100 m) of the produced adhesive film were fixed on both sides of a horizontal tensile tester, and 200% An elongated specimen was prepared by adhering a glass plate on the lower part and a releasing film on the lower part and an adhesive film having passed through a 2 Kg roller in the stretched state (twice the initial length and 10 cm in the sample). After removal of the release film on the top, the haze was measured by the same method as the haze measurement.

(6) Recovery power: When both end portions of a PET (polyethylene terephthalate) film (thickness: 75 m) of width × length (50 mm × 20 mm) were respectively referred to as a first end portion and a second end portion, The end portions of each of the two PET films were adhered to each other with an adhesive film of a length and a length (20 mm x 20 mm) manufactured from the past to adhere to the first end portion of the PET film / the second end portion of the PET film / , And the contact area between the PET film and the adhesive film is measured as a test piece having a width and a length (20 mm x 20 mm). 5A, a jig is fixed to both end portions of the PET film without the pressure-sensitive adhesive film of the specimen at room temperature (25 DEG C) , The one jig is fixed and the other jig is pulled by a length of 1000% (10 times the initial thickness of the adhesive film, X ₀ ) of the thickness (unit: 탆) of the adhesive film at a speed of 300 mm / Sec and the length of the adhesive film stretched when a force of 0 kPa is applied to the adhesive film is restored to the same speed (300 mm / min) as the pulling speed is denoted by X _f (unit: 1, the recovery power (%) was calculated.

[Formula 1]

Recovery power (%) = (1- (X _f / X ₀ )) x 100

(7) Elongation (%): An adhesive film (thickness: 100 占 퐉) having a size of 5 cm 占 5 cm was rolled so as to tightly adhere tightly to TA (TA.XT_Plus Texture Analyzer (Stable Micro System) And the rate of change of the length until it is cut off is measured.

(8) Bubble generation area (%): An adhesive film having a thickness of 50 占 퐉 on one side of an adhesive film (13 cm 占 3 cm and a thickness of 100 占 퐉) and a PET film having a thickness of 100 占 퐉 on the back surface of the above- Was bent in a PET direction of 50 占 퐉 in such a manner that the transverse length of the adhesive film was 1/2 between 1 cm-wide parallel frames, aged at a temperature of 70 占 폚 and a humidity of 93% for 24 hours, EX-51) was analyzed with Mountech's Mac-view software, and the ratio of the size of the bubble to the area occupied by the area was measured (%).

Example One :

The following layers were laminated to produce a flexible display device (13 cm x 3 cm).

- Optical element: PET (thickness 100 μm) was used.

First Adhesive Film: An adhesive film having a thickness of 100 占 퐉 was formed from the composition of Production Example 1.

- PC film coated with transparent electrode (touch function part): 50um Teijin chemical PC film was prepared by applying silver nano wire containing solution (Clearohm-A G4-05, Cambrios, including silver nanowire and binder).

Second adhesive film: An adhesive film having a thickness of 50 占 퐉 was formed from the composition of Production Example 1.

- Window film: PET film (100um Cosmoshine TA015, Toyobo, thickness: 100um) was substituted.

Example 2 to 8

A flexible display device was manufactured in the same manner as in Example 1, except that Production Examples 2 to 8 were used as the pressure-sensitive adhesive composition for forming an adhesive film.

Comparative Example One

A flexible display device was manufactured in the same manner as in Example 1, except that the pressure-sensitive adhesive composition for forming a pressure-sensitive adhesive film used in Production Example 9 was used.

The following properties of the above Examples 1 to 8 and Comparative Example 1 were evaluated and shown in Table 2.

Example Comparative Example One 2 3 4 5 6 7 8 One Bubble generation area (%) 0 0 0 0 0 0 0 0 3.22

As shown in Table 2, it can be seen that the embodiment using the adhesive film of the present invention is excellent in reliability with a bubble generation area of 0%.

Property evaluation method

Bubble generation area (%): The manufactured display device (window film was replaced with a PET film (thickness 100 탆)) was bent in the direction of the PET film (thickness 100 탆) between parallel frames spaced 1 cm apart, , The film was aged at a humidity of 93% for 24 hours and an adhesive film was measured with an optical microscope (Olympus, EX-51, and 30 magnification) by using Mountech's Mac-view software. (%) Obtained by measuring the ratio of the area occupied.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the embodiments described above are in all respects illustrative and not restrictive.

Claims

Optical element;
A first adhesive film formed on the optical element;
A touch function unit formed on the first adhesive film;
A second adhesive film formed on the touch functional part; And
And a window film formed on the second adhesive film,
The first adhesive film or the second adhesive film is characterized in that the distribution of storage modulus according to the temperature at which the temperature is x axis (° C) and the storage modulus is the y axis (KPa) is in the range of -20 ° C. to 80 ° C. A slope of -9.9 to 0,
Wherein the first adhesive film or the second adhesive film has a storage modulus of 10 KPa or more at 80 ° C.

Optical element;
A first adhesive film formed on the optical element;
A touch function unit formed on the first adhesive film;
A second adhesive film formed on the touch functional part; And
And a window film formed on the second adhesive film,
Wherein the first adhesive film or the second adhesive film comprises a monomer mixture forming a (meth) acrylic copolymer having a hydroxyl group; And organic particles, wherein the pressure-
Wherein the average particle diameter of the organic particles is 10 nm to 400 nm.

The flexible display device according to claim 1 or 2, further comprising a polarizer formed on the touch function unit or the first adhesive film.

The flexible display device according to claim 1 or 2, wherein the touch function portion includes a base layer, and the base layer includes a polarizer.

The flexible display device according to claim 1 or 2, wherein the optical element is an LCD including an OLED, an LED, or a light source.

The flexible display device according to claim 1 or 2, wherein the thickness of the first adhesive film is thicker than that of the second adhesive film.

The method according to claim 1 or 2, wherein the first adhesive film or the second adhesive film has a T-peel peel strength at 25 DEG C of not more than 400 gf / in To 5,000 gf / in.

The method according to claim 1 or 2, wherein the first adhesive film or the second adhesive film has a T-peel peel strength of 60 g / cm < 2 > at 60 DEG C on a corona-treated polyethylene terephthalate (PET) To 3,000 gf / in.

The flexible display device according to claim 2, wherein the first adhesive film or the second adhesive film has a storage modulus of 10 KPa to 1000 KPa at 80 ° C.

The flexible display device according to claim 1 or 2, wherein the first adhesive film or the second adhesive film has a storage modulus of 10 KPa to 1000 KPa at -20 캜.

The flexible display device according to claim 1 or 2, wherein the first adhesive film or the second adhesive film has a thickness of 100 m and a haze after 200% stretching of 5% or less.

3. The flexible display device according to claim 1 or 2, wherein the first adhesive film or the second adhesive film has a recovery force of 30% to 98% according to the following formula 1 at a thickness of 100 m:
[Formula 1]
Recovery power (%) = (1- (X _f / X ₀ )) x 100
(Both sides of a PET (polyethylene terephthalate) film (thickness: 75 占 퐉) of a width × length (50 mm × 20 mm) in the above formula 1 is referred to as a first end portion and a second end portion, (20 mm x 20 mm) of the PET film / second end portion of the PET film (20 mm x 20 mm), and the second end portion / And the other jig was pulled at a speed of 300 mm / min to obtain a thickness of the pressure-sensitive adhesive film (unit: (10 times the thickness, X ₀ ) of 10% of the thickness of the adhesive film (10 mm thickness) and then held for 10 seconds and restored to the same speed as the pulling speed (300 mm / min) to apply a force of 0 kPa The length of the stretched adhesive film is X _f (unit: 탆)).

The flexible display device according to claim 1 or 2, wherein the first adhesive film or the second adhesive film has an elongation of 800% to 2000%.

The method according to claim 1 or 2, wherein a PET film having a thickness of 50 占 퐉 is formed on one side of the first adhesive film (13 cm 占 3 cm, thickness 100 占 퐉) or the second adhesive film (13 cm 占 3 cm, And a pressure-sensitive adhesive film having a thickness of 100 탆 laminated on the back surface of the pressure-sensitive adhesive film was bent in a PET direction of 50 탆 so that the transverse length of the pressure-sensitive adhesive film was 1/2 between parallel frames spaced by 1 cm, Wherein the bubble generation area is 0% when aged at a humidity of 93% for 24 hours.

The flexible display device according to claim 1 or 2, wherein the window film of the flexible display device is replaced with a PET film (100 탆 thick), bent in the direction of the PET film between parallel frames spaced by 1 cm, Wherein the bubbling area of the first adhesive film or the second adhesive film is 0% when aged at a humidity of 93% for 24 hours.

The method of claim 1, wherein the first adhesive film or the second adhesive film is a cured product of a pressure-
Wherein the pressure-sensitive adhesive composition comprises a monomer mixture and organic particles forming a (meth) acrylic copolymer having a hydroxyl group.

The flexible display device according to claim 16, wherein the organic particles have an average particle diameter of 10 nm to 400 nm.

The flexible display device according to claim 2 or claim 16, wherein the monomer mixture forming the (meth) acrylic copolymer having a hydroxyl group comprises a (meth) acrylate having a hydroxyl group and a comonomer.

The flexible display device according to claim 2 or claim 16, wherein the organic particles have a core-shell structure, and the glass transition temperature of the core and the shell satisfy the following formula 2:
[Formula 2]
Tg (c) < Tg (s)
Tg (c) is the glass transition temperature (占 폚) of the core, and Tg (s) is the glass transition temperature (占 폚) of the shell.

The flexible display device according to claim 19, wherein the core has a glass transition temperature of -150 캜 to 10 캜, and the shell has a glass transition temperature of 15 캜 to 150 캜.

20. The method of claim 19, wherein the core comprises at least one polyalkyl (meth) acrylate having a glass transition temperature of from -150 DEG C to 10 DEG C, the shell having a glass transition temperature of from 15 DEG C to 150 DEG C, (Meth) acrylate.

20. The method of claim 19, wherein the core or shell comprises two or more layers,
Wherein the outermost layer of the organic particles comprises at least one polyalkyl (meth) acrylate having a glass transition temperature of 15 to 150 캜.

The flexible display device according to claim 19, wherein the shell comprises 1 wt% to 70 wt% of the organic particles.

The flexible display device according to claim 16, wherein the organic particles are contained in an amount of 0.1 to 15 parts by weight based on 100 parts by weight of a monomer mixture forming a (meth) acrylic copolymer having a hydroxyl group.

The flexible display device according to claim 2 or claim 16, wherein the organic particles have a refractive index difference of 0.05 or less from the (meth) acrylic copolymer having a hydroxyl group formed from the monomer mixture.

The composition according to claim 25, wherein the (meth) acrylic copolymer having a hydroxyl group is polymerized from a monomer mixture comprising 5 to 40% by weight of a (meth) acrylate having a hydroxyl group and 60 to 95% by weight of a comonomer Lt; / RTI >

19. The composition of claim 18, wherein the comonomer is selected from the group consisting of alkyl (meth) acrylate monomers, monomers with ethylene oxide, monomers with propylene oxide, monomers with amine groups, monomers with amide groups, monomers with alkoxy groups, At least one of a monomer having a sulfonic acid group, a monomer having a phenyl group, and a monomer having a silane group,
Wherein the comonomer has a glass transition temperature (Tg) of -150 캜 to 0 캜.

The flexible display device according to claim 2 or claim 16, wherein the pressure-sensitive adhesive composition further comprises at least one of an initiator and a crosslinking agent.