WO2018155787A1 - Polarizer-integrated window laminate and image display device including same - Google Patents

Abstract

A polarizer-integrated window laminate of the present invention, comprises: a window film; and a point-adhesive layer and a polarizer which are sequentially laminated on one side of the window film, the point-adhesive layer being capable of having an adhesive force according to a specific formula. The window laminate has improved adhesive force, peeling resistance, and bending properties at room temperature and high temperature and high humidity, and can be effectively applied to a flexible display.

Description

Polarizing plate integrated window laminate and image display device comprising the same

The present invention relates to a polarizing plate integrated window laminate and an image display device including the same.

In recent years, display devices capable of displaying information including image images have been actively developed. The display device includes a liquid crystal display (LCD) device, an organic light emitting display (OLED) device, a plasma display panel (PDP) device, and a field emission display (FED) device. ) Devices and the like.

In the display device, for example, a window substrate may be disposed on the display panel such as an LCD panel and an OLED panel to protect the display panel from an external environment. The window substrate is formed of a glass material, and as the flexible display is recently developed, a transparent plastic material is used as the window substrate.

In addition, additional members of a display device such as a polarizer and a touch screen panel may be disposed between the window substrate and the display panel. For example, external light reflected from the electrode pattern of the display panel may be blocked by the polarizer. In addition, the user's command may be input through the touch screen panel.

However, as a plurality of layers or structures, such as the polarizing plate, the touch screen panel, and the window substrate, are stacked on the display panel, there is a limit in that the requirements in recent display devices such as flexible characteristics and thinning are sufficiently implemented. exist. In addition, as the plurality of layers or structures are stacked, sufficient flexibility cannot be easily secured while maintaining mechanical strength and stability.

For example, Korean Patent Publication No. 2012-0076026 discloses a transparent substrate including a touch screen panel including a polarization layer.

One object of the present invention is to provide a polarizing plate-integrated window laminate having improved mechanical reliability and flexible properties.

One object of the present invention is to provide an image display device including a polarizing plate-integrated window laminate having improved mechanical reliability and flexible characteristics.

1.window film; And an adhesive layer and a polarizing plate sequentially stacked on one surface of the window film, and satisfying Equation 1 below:

[Equation 1]

Ya + Yb> 20

(In Formula 1 Ya represents the room temperature adhesive strength of the adhesive layer, Yb represents the moisture-resistant adhesive strength of the increasingly adhesive layer, Ya is calculated by the following formula 2, Yb is calculated by the following formula 3,

[Formula 2]

[Equation 3]

In Formulas 2 and 3, a represents the surface energy of the polarizing plate, a 'represents the surface energy of the window film, and b represents the surface energy of the adhesive layer.

2. The polarizing plate-integrated window laminate according to the above 1, wherein the first surface energy ratio represented by a / b is 2 or less, and the second surface energy ratio represented by a '/ b is 3 or less.

3. In the above 1, wherein the window film comprises a polyimide, the adhesive layer comprises an acrylic optical transparent adhesive agent (OCA), polarizing plate integrated window laminate.

4. In the above 1, wherein the polarizing plate comprises a first protective film and a polarizer, the surface energy of the polarizing plate is measured on the surface of the first protective film, polarizing plate integrated window laminate.

5. In the above 4, wherein the first protective film is in contact with the adhesive layer, comprising a cyclic olefin-based polymer (COP), polarizing plate integrated window laminate.

6. In the above 5, further comprising a second protective film facing the first protective film with the polarizer therebetween, the polarizing plate integrated window laminate.

7. In the above 6, wherein the second protective film comprises a COP film or retardation film, polarizing plate integrated window laminate.

8. In the above 1, wherein at least one surface of the window film, the polarizing plate or the adhesive layer is corona treated, polarizing plate integrated window laminate.

9. according to the above 1, the storage modulus of the increasingly adhesion layer is 0.01 to 0.5 Mpa in the temperature range of -20 to 80 ℃, polarizing plate integrated window laminate.

10. In the above 1, further comprising a hard coating layer formed on the other surface of the window film, polarizing plate integrated window laminate.

11. The image display device of any one of the above 1 to 10, comprising a window stack.

12. The image display device according to above 11, which is a flexible display device.

The window laminate of the present invention includes a window film and a polarizing plate bonded to each other by an adhesive layer, and can secure excellent room temperature adhesiveness and moisture resistance adhesive strength through surface energy control in each of the window film, the adhesive layer, and the polarizing plate. have.

Therefore, even in the bending or folding operation, a highly reliable window laminate in which defects such as delamination and cracking are suppressed can be realized. In addition, even in a high temperature, high humidity harsh environment, the desired mechanical properties of the window laminate can be maintained for a long time.

Since the window stack according to the exemplary embodiments has excellent flexibility and folding characteristics, the window stack may be effectively applied as a window or cover member of the flexible display.

1 is a schematic cross-sectional view illustrating a window stack according to exemplary embodiments of the present invention.

2 is a schematic diagram showing a contact angle measurement for surface energy calculation.

3 and 4 are schematic cross-sectional views illustrating a window stack in accordance with some example embodiments.

The present invention includes a window film, and an adhesive layer and a polarizing plate sequentially stacked on one surface of the window film, wherein the adhesive layer is provided with a window laminate that satisfies the adhesive force according to a specific formula. The window laminate has improved adhesion, peeling resistance, and bending characteristics at room temperature, high temperature, and high humidity, and can be effectively applied to a flexible display.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Although the following describes preferred embodiments of the present invention, these embodiments are only illustrative of the present invention and are not intended to limit the scope of the appended claims, and various modifications to the embodiments within the scope and spirit of the present invention. Modifications and variations are apparent to those skilled in the art, and such variations and modifications are naturally within the scope of the appended claims.

< window Laminate >

1 is a schematic cross-sectional view illustrating a window stack according to exemplary embodiments of the present invention. 2 is a schematic diagram showing a contact angle measurement for surface energy calculation.

Referring to FIG. 1, the window stack may include an adhesive layer 120 and a polarizer 150 sequentially stacked on the window film 100. According to exemplary embodiments, the window laminate may be a polarizing plate-integrated window laminate in which the window film 100 and the polarizing plate 150 are integrally bonded.

The window film 100 may be applied to, for example, an LCD device, an OLED device, a touch screen panel (TSP), or the like, and may include a material having durability against external impact and transparency that a user can see. In addition, the window film 100 may include a plastic material having a predetermined flexibility. In this case, the display device to which the window stack is applied may be provided as a flexible display. The window film 100 may include a glass material in which a flexible property is implemented.

In terms of enhanced flexibility, the window film 100 may be formed to include polyimide. For example, the window film 100 including the polyimide may be formed by curing a composition including the polyimide precursor.

The polyimide precursor may include dihydrides such as tetra carboxylic acid dianhydride and aromatic diamines. When the dianhydride and the diamine compound react, a polyamic acid (PAA) is prepared, and the imidization reaction may proceed by the nitrogen atom of the amide of the polyamic acid attacking the carbon atom of the carboxyl group by heat treatment or an appropriate catalytic reaction. have. Accordingly, the window film 100 including the polyimide may be manufactured.

In some embodiments, the imidization ratio may be adjusted in consideration of the improved moisture barrier performance and flexibility of the window film 100, and the surface energy of the window film 100 may vary according to the imidization ratio. have. Additionally, hydrophobic components can be introduced into the polyimide. For example, the window film 100 may be prepared by introducing a fluoro methyl component into the polyimide molecule or by mixing silica particles. In this case, the surface energy of the window film 100 may change according to the content of the hydrophobic component.

As shown in FIG. 1, the window film 100 may include one surface 100b and the other surface 100a. According to exemplary embodiments, one surface 100b and the other surface 100a may be surfaces facing each other. For example, one surface 100b may correspond to a lower surface of the substrate 100, and the other surface 100a may correspond to an upper surface of the substrate 100.

The other surface 100a may be an exposed surface or a viewing surface of the window film 100 when the window stack is applied to the image display device. For example, an image is implemented to the user on the other surface 100a side of the window film 100, and a user's command (eg, through a touch) may be input. One surface 100b of the window film 100 faces the display panel, for example, and additional layers and / or structures of the window stack may be stacked on the surface 100b.

The adhesive layer 120 may be formed on one surface 100b of the window film 100. As used herein, the term "adhesive layer" is used to encompass the adhesive layer and the adhesive layer. The adhesive layer 120 may be formed using a pressure sensitive adhesive (PSA) composition or an optically clear adhesive (OCA) composition.

The adhesive layer 120 may have an appropriate adhesive force to prevent peeling, bubbles, etc. when bending occurs in the window stack, and may have viscoelastic properties applicable to the flexible display. In one embodiment, the storage modulus of the increasingly adhesion layer 120 may be about 0.01 to 0.5 Mpa in the temperature range of about -20 to 80 ℃. The adhesive force of the adhesive layer 120 may be maintained without peeling or lifting by the adhesive layer 120 within the storage elastic modulus range.

In some embodiments, the adhesive layer 120 may be formed using an acrylic or silicone OCA composition.

For example, the acrylic OCA composition may include a (meth) acrylic acid ester copolymer, a crosslinking agent, and a solvent. For example, the (meth) acrylic acid ester copolymer may be prepared by copolymerizing a (meth) acrylic acid ester, an alkoxysilyl group-containing monomer, and a functional monomer.

The type of the crosslinking agent is not particularly limited and may be appropriately selected and used among those commonly used in the art. For example, the crosslinking agent may include a polyisocyanate compound, an epoxy resin, a melamine resin, a urea resin, a dialdehyde, a methylol polymer, and the like, and preferably a polyisocyanate compound may be used.

The solvent may include a conventional solvent used in the field of resin composition, for example, alcohol-based (methanol, ethanol, isopropanol, butanol, propylene glycol methoxy alcohol, etc.), ketone-based (methyl ethyl ketone, methyl butyl Ketone, methyl isobutyl ketone, diethyl ketone, dipropyl ketone, etc.), acetate type (methyl acetate, ethyl acetate, butyl acetate, propylene glycol methoxy acetate, etc.), cellosolve type (methyl cellosolve, ethyl cellosolve, propyl) Cellosolves, etc.), hydrocarbon-based (normal hexane, normal heptane, benzene, toluene, xylene, etc.) may be used. These may be used alone or in combination of two or more thereof.

The acrylic OCA composition may further include various known additives, for example, a plasticizer, a silane coupling agent, a light stabilizer, and the like, within a range that does not impair adhesion, durability, and viscoelastic properties of the adhesive layer 120.

For example, the surface energy of the adhesive layer 120 may be changed or adjusted according to the content of the above-described monomers, the content of the crosslinking agent, the degree of crosslinking of the copolymer and the like. The adhesive layer 120 does not cause lifting and peeling between the interfaces, and may satisfy room temperature adhesion and moisture resistance adhesion in a range described later in order to maintain adhesion in a harsh environment.

The polarizer 150 may be bonded to the window film 100 through the adhesive layer 120. For example, the OCA composition may be coated and cured on the upper surface of the polarizing plate 150 to form an adhesive layer 120, and the adhesive layer 120 may be attached to the window film 100.

The polarizing plate 150 may include a laminated structure of the first protective film 130 and the polarizer 140, and the first protective film 130 may be attached to the adhesive layer 120.

The first protective film 130 may be, for example, polyester resins such as polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate, polybutylene terephthalate and the like; Cellulose resins such as diacetyl cellulose and triacetyl cellulose; Polycarbonate resins; Acrylic resins such as polymethyl (meth) acrylate and polyethyl (meth) acrylate; Cyclic olefin polymer (COP) and the like. In one embodiment, the first protective film 130 may be a COP material film in consideration of transparency, mechanical strength, thermal stability, moisture shielding, isotropy.

The polarizer 140 may include, for example, a stretched polyvinyl alcohol (PVA) -based resin. The polyvinyl alcohol-based resin may be preferably a polyvinyl alcohol-based resin obtained by saponifying a polyvinyl acetate-based resin. As polyvinyl acetate type resin, the copolymer etc. of vinyl acetate and the other monomer copolymerizable with this besides the polyvinyl acetate which is a homopolymer of vinyl acetate are mentioned. Examples of the other monomers include unsaturated carboxylic acid type, unsaturated sulfonic acid type, olefin type, vinyl ether type, and acrylamide monomer having an ammonium group. The polyvinyl alcohol-based resin may be modified, for example, polyvinyl formal or polyvinyl acetal modified with aldehydes.

In one embodiment, the surface contacting the adhesive layer 120 of the first protective film 130 may include, for example, roughness formed through surface treatment such as corona treatment, primer treatment, alkali treatment, and the like. In addition, the surface of one surface 100b of the window film 100 and / or the adhesive layer 120 may also be surface treated.

According to embodiments of the present invention, the adhesive layer 120 may satisfy the following Equation 1.

[Equation 1]

Ya + Yb> 20

In Equation 1, Ya represents the room temperature adhesion of the adhesive layer 120, and Yb represents the moisture resistance adhesion of the increasingly adhesive layer 120. Ya and Yb may be expressed in units of Newtons (N), respectively, in which case the sum of the room temperature adhesiveness and the moisture resistance adhesive strength of the adhesive layer 120 may exceed 20N.

In some embodiments, the sum of Ya and Yb may be 25 or more.

Ya and Yb may be calculated through Equations 2 and 3 below, respectively.

[Formula 2]

[Equation 3]

In Equations 2 and 3, a represents the surface energy of the polarizing plate 150. For example, a denotes surface energy measured on the upper surface of the first protective film 130. a 'represents the surface energy of the window film 100. For example, a 'represents surface energy measured at one surface 100b of the window film 100. b represents the surface energy of the adhesive layer 120.

The surface energy can be calculated through an empirical formula by measuring the contact angle.

Referring to FIG. 2, after dropping a droplet on a surface of an object for measuring surface energy, a contact angle θ may be measured by showing a tangent line at a contact point of the object and the droplet.

As shown in "A" of FIG. 2, when the droplets have hydrophilicity or high wettability, the contact angle increases and when the droplets have hydrophobicity or low wetting as shown in "B", the contact angle decreases.

According to the exemplary embodiments, after dropping the droplets on the surface of the window film 100, the adhesive layer 120 and the polarizing plate 150, the contact angle is measured, and the contact angle is substituted into the empirical formula for the window film ( 100), the surface energy of each of the adhesive layer 120 and the polarizer 150 may be calculated.

The empirical formula is, for example, obtained by combining the empirical formula of Owen-Wendt and the equation of Young, can be represented by the following formula (4).

[Equation 4]

은 액적의 표면 에너지를 나타내며,

는 대상체의 전체 표면에너지를 나타낸다. 위첨자 d는 비극성 성분을 나타내며 및 p는 극성 성분을 나타낸다. 대상체의 전체 표면에너지는 하기의 수식 5로 계산될 수 있다.In Equation 4,

Represents the surface energy of the droplet,

Represents the total surface energy of the object. Superscript d represents the nonpolar component and p represents the polar component. The total surface energy of the object may be calculated by Equation 5 below.

[Equation 5]

와

를 구할 수 있다. 따라서, 대상체의 전체 표면에너지

가 계산될 수 있다. 윈도우 필름(100), 점접착층(120) 및 편광판(150)의

가 각각 계산되어 상기 수식 2 및 3에서 a', b 및 a의 값으로 활용될 수 있다,In some embodiments, the contact angle is measured by using different first droplets and second droplets, and then substituted and coalesced in Equation 4 above.

Wow

Can be obtained. Therefore, the total surface energy of the object

Can be calculated. Of the window film 100, the adhesive layer 120 and the polarizing plate 150

May be calculated to be used as the values of a ', b and a in Equations 2 and 3, respectively.

For example, water may be used as the first droplet, and di-iodomethane may be used as the second droplet.

Referring back to Equations 2 and 3, a / b is the first surface energy ratio and may be used as an indicator of room temperature adhesive force. a '/ b is the second surface energy ratio and may be utilized as an index of moisture resistance adhesion.

In some embodiments, the first surface energy ratio may be about 2 or less, and the second surface energy ratio may be about 3 or less.

In the window laminate according to the embodiments of the present invention, the adhesive layer 120 satisfies the above-described formulas, and the interlayer peeling, cracking, deformation of optical properties, etc. when bending or folding occurs at high temperature and high humidity conditions as well as at room temperature conditions. It may not cause a defect. Therefore, a highly reliable and highly durable window laminate applicable to the flexible display can be implemented.

3 and 4 are schematic cross-sectional views illustrating a window stack in accordance with some example embodiments.

Referring to FIG. 3, the window stack may further include a hard coating layer 105. The hard coating layer 105 may be formed on the other surface 100a of the window film 100. In this case, the surface of the hard coating layer 105 may be exposed to the user's viewing side.

The hard coating layer 105 is formed using a hard coating composition including a photocurable compound, a photoinitiator, and a solvent, thereby additionally securing excellent flexibility, wear resistance, and surface hardness of the window film 100.

The photocurable compound may include, for example, a siloxane compound, an acrylate compound, a compound having a (meth) acryloyl group or a vinyl group. These may be used alone or in combination of two or more thereof.

Examples of the siloxane compound may include a polydimethylsiloxane (PDMS) compound. The siloxane compound may contain an epoxy group such as a glycidyl group. Accordingly, crosslinking or curing through epoxy ring opening may be promoted by light irradiation.

Examples of the acrylate-based compound include dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate And (meth) acrylate containing an oxyethylene group, ester (meth) acrylate, ether (meth) acrylate, epoxy (meth) acrylate, melamine (meth) acrylate, and the like.

Examples of the compound having a (meth) acryloyl group or a vinyl group include (meth) acrylic acid esters, N-vinyl compounds, vinyl-substituted aromatics, vinyl ethers and vinyl esters.

The photoinitiator is not particularly limited as long as the photoinitiator generates ions, Lewis acids or radicals by irradiation with active energy rays such as visible light, ultraviolet light, X-rays or electron beams to initiate the polymerization reaction of the photocurable compound. Examples of the photoinitiator include onium salts such as aromatic diazonium salts, aromatic iodonium salts and aromatic sulfonium salts, acetphenone compounds, benzoin compounds, benzophenone compounds, thioxanthone compounds and the like.

The solvent may use a solvent substantially the same as or similar to that used in the PSA composition, and is not particularly limited.

In some embodiments, the hard coating composition may further include a UV absorber. The ultraviolet absorbent may be used without particular limitation as long as it is a compound capable of absorbing an ultraviolet wavelength of about 380 nm or less. In some embodiments, the ultraviolet absorber may include a benzoxazinone-based compound, a triazine-based compound, a benzotriazole-based compound, or a benzophenone-based compound. . These may be used alone or in combination of two or more. Accordingly, the UV transmittance is reduced by the hard coating layer 105 to improve the optical properties and visible light transmittance of the window laminate.

In some embodiments, the window film may further include at least one functional layer applied to an image display device such as an anti-scattering film, an anti-fingerprint film, or the like.

Referring to FIG. 4, the polarizer 155 may further include a second protective film 160. The polarizing plate 155 has a laminated structure of the first protective film 130, the polarizer 140, and the second protective film 160, and the second protective film 160 has a first protective contact with the adhesive layer 120. The film 130 may be opposite to each other.

In one embodiment, the second protective film 160 may be formed of a material substantially the same as or similar to the first protective film 130.

In one embodiment, the second protective film 160 may include an optical functional layer. A retardation film is mentioned as an example of the said optical function layer. The retardation film may be included as a functional layer for retarding the phase of light passing through the polarizer 140. The material of the retardation film is not particularly limited, and may include a gradient stretched resin film, a liquid crystal coating layer, and the like.

For example, the retardation film may comprise a λ / 4 film. The retardation film may have, for example, a multilayer structure in which a λ / 4 film and a λ / 2 film are laminated.

The window stack may further include a touch sensor layer 190. The touch sensor layer 190 may include, for example, sensing electrodes 185 for converting a user's touch signal input through the window film 100 into an electrical signal. For example, the sensing electrodes may include first sensing electrodes and second sensing electrodes arranged to cross each other.

The sensing electrode 185 may include, for example, a transparent conductive material. Examples of the transparent conductive material include indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium zinc tin oxide (IZTO), cadmium tin oxide (CTO), and metal wires. These can be used individually or in combination of 2 or more types. In example embodiments, the electrode pattern may include ITO. The metal used for the metal wire is not particularly limited, and may include, for example, silver, gold, aluminum, copper, iron, nickel, titanium, telenium, chromium, or an alloy thereof.

Peripheral wires connected to the sensing electrodes 185 may be further formed in the touch sensor layer 190.

In some embodiments, the touch sensor layer 190 may be bonded to the polarizer 155 through the second adhesive layer 170. The adhesive layer 120 described in FIGS. 1 and 3 is referred to as the first adhesive layer 120 in FIG. 4.

The sensing electrodes 185 may be formed on the substrate 187, and a passivation layer 180 may be formed on the substrate 187 to cover the sensing electrodes 185.

The touch sensor layer 190 may be coupled to the window stack in the form of a touch screen panel (TSP), for example. For example, the touch sensor layer 190 may be bonded to the polarizer 155 through the second adhesive layer 170.

<Image display device>

Embodiments of the present invention further provide an image display apparatus including the above-described window stack.

For example, the window stack may be combined with a display panel included in an OLED device, an LCD device, or the like. The display panel may include a pixel circuit including a thin film transistor (TFT) arranged on a substrate, and a pixel portion or a light emitting portion electrically connected to the pixel circuit.

For example, the display panel may include a base substrate including a flexible resin such as polyimide, and may be combined with the window stack to implement a flexible display device. As described above, the window film 100 of the window laminate also includes a material having enhanced flexibility, such as polyimide, and has improved room temperature and moisture resistance adhesive strength by the adhesive layer 120 satisfying the above-described physical properties or formulas. Can be implemented. Therefore, mechanical durability and reliability may be maintained even when a stress due to folding or bending is applied to the flexible display device.

Hereinafter, experimental examples including preferred embodiments are provided to help understanding of the present invention, but these examples are only for exemplifying the present invention, and do not limit the appended claims, and the scope and spirit of the present invention. It is apparent to those skilled in the art that various changes and modifications to the embodiments can be made within the scope, and such variations and modifications are within the scope of the appended claims.

Example  And Comparative example

COP film was used as a protective film of a polarizing plate, and polyimide film was used as a window film.

The adhesive adhesive layer was formed using the acrylic OCA composition of Lintec. The adhesive layer samples of Examples and Comparative Examples were prepared from different OCA compositions in terms of type and content of acrylate monomers.

For the protective film and the adhesive layer, the contact angle was measured using water and diiomethane, and the total surface energy of each of the protective film and the adhesive layer was calculated using Equations 4 and 5. Thereafter, the first surface energy ratio expressed by a / b in Equation 2 was calculated, and through this, the room temperature adhesive force of the adhesive layer was converted. Contact angle was measured using a KSV Instruments (Model: CAM 101). Specifically, the average value was used after five measurements while changing the position of the drop.

The measurement results mentioned above are shown in Table 1 below.

The contact angle was measured using water and diiomethane for the window film and the adhesive layers, and total surface energy of each of the window film and the adhesive layer was calculated using Equations 4 and 5. Thereafter, a second surface energy ratio expressed by a '/ b in Equation 3 was calculated, and through this, the moisture resistance adhesion of the adhesive layer was converted.

The measurement results mentioned above are shown in Table 2 below.

Experimental Example

A window laminate was manufactured by bonding the window film and the polarizing plate through the adhesive layer according to the above-described examples and comparative examples, and evaluated crack resistance and adhesion as follows.

(One) Crack resistance  evaluation

A sample was prepared by cutting the window laminate to a size of 1 cm × 10 cm, and a bending test of 100,000 times was performed at a radius of curvature of 2 mm. Thereafter, the window laminate was visually evaluated for cracking. Evaluation criteria are as follows.

○: no crack observed throughout the sample

(Triangle | delta): Partial crack observation at a curved part

X: Cracks propagate throughout the sample area

(Crack occurrence: X, no crack occurrence: O)

(2) adhesion evaluation

After eleven straight lines were formed on the window film side of the window laminates of Examples and Comparative Examples at 1 mm intervals, respectively, to make 100 squares, and then three peel tests were performed using a tape (CT-24, Nichi-Nishi). Proceeded. Three sets of 100 squares were tested and averaged.

Adhesion was measured as follows.

i) adhesion = n / 100

ii) n: number of rectangles that do not peel out of the entire rectangle, 100: number of whole rectangles

When none was peeled off, it was recorded as 100/100.

(3) bending evaluation

The bending test according to the evaluation standard IEC-62715 was carried out using the bending evaluation equipment (DLDMLH-FS, manufactured by YUASA SYSTEM) for the window laminate according to the examples and the comparative examples. Specifically, 10,000 bending tests were performed on the window laminates at 60 ^° C. and 90% relative humidity. After the bending test, the window laminates were evaluated for peeling and bubble generation as follows.

<Evaluation Criteria>

○: no bubbles or peeling

△: partial swelling of the adhesive layer or the protective film occurs

X: Peeling of films | membrane clearly observed from the folding part of a laminated body

The evaluation results are shown in Table 3 below. Meanwhile, in Table 3, the sum (Ya + Yb) of the room temperature adhesive strength and the moisture resistance adhesive strength of the examples and the comparative examples is shown together.

Referring to Table 3, in the case of Examples 1 to 3 satisfying the relationship of Equation 1 (Ya + Yb> 20), better crack resistance, adhesiveness, and bending characteristics than the comparative example were obtained.

In addition, the best crack resistance, adhesion and flexural characteristics results were obtained in Example 3 in which the first surface energy ratio (a / b) was 2 or less and the second surface energy ratio (a '/ b) was 3 or less.

Meanwhile, the surface energy was measured after performing surface treatment through corona treatment on the surfaces of the protective film, the adhesive layer and the window film of the window laminate of Comparative Example described above. The measurement results are shown in Table 4. Specifically, corona treatment was performed at a spacing between the electrodes of 2 mm, a voltage of 8.61 kV and a treatment rate of 6 m / min.

Based on the surface energy of Table 4, the first surface energy ratio (a / b) was calculated as 1.7 and the second surface energy ratio (a '/ b) was calculated as 3.05. Yb) was measured to be 12.81 and 16.87, respectively. Therefore, it was possible to improve the adhesive strength of the comparative example to satisfy the formula 1 through the surface treatment.

Claims (12)

Window film; And It includes an adhesive layer and a polarizing plate sequentially stacked on one surface of the window film, A polarizing plate integrated window laminate that satisfies the following Equation 1: [Equation 1] Ya + Yb> 20 (In Formula 1 Ya represents the room temperature adhesive strength of the adhesive layer, Yb represents the moisture-resistant adhesive strength of the increasingly adhesive layer, Ya is calculated by the following formula 2, Yb is calculated by the following formula 3, [Formula 2]

[Equation 3]

In Formulas 2 and 3, a represents the surface energy of the polarizing plate, a 'represents the surface energy of the window film, and b represents the surface energy of the adhesive layer. The polarizing plate integrated window laminate according to claim 1, wherein the first surface energy ratio represented by a / b is 2 or less, and the second surface energy ratio represented by a '/ b is 3 or less. The polarizing plate integrated window laminate of claim 1, wherein the window film comprises a polyimide, and the adhesive layer includes an acrylic optical transparent adhesive agent (OCA). The polarizing plate-integrated window laminate according to claim 1, wherein the polarizing plate comprises a first protective film and a polarizer, and the surface energy of the polarizing plate is measured in terms of the first protective film. The polarizing plate integrated window laminate of claim 4, wherein the first protective film is in contact with the adhesive layer and includes a cyclic olefin polymer (COP). The polarizing plate integrated window laminate of claim 5, further comprising a second protective film facing the first protective film with the polarizer therebetween. The polarizing plate integrated window laminate of claim 6, wherein the second protective film comprises a COP film or a retardation film. The polarizing plate integrated window laminate according to claim 1, wherein a surface of at least one of the window film, the polarizing plate, or the adhesive layer is corona treated. The polarizing plate-integrated window laminate according to claim 1, wherein the storage modulus of the increasingly adhesion layer is 0.01 to 0.5 Mpa at a temperature range of -20 to 80 ° C. The polarizing plate integrated window laminate according to claim 1, further comprising a hard coating layer formed on the other surface of the window film. The image display apparatus containing the polarizing plate integrated window laminated body of any one of Claims 1-10. The image display device according to claim 11, which is a flexible display device.

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