Adhesive film for OLED display device

Abstract

The present invention relates to an adhesive film for an OLED display device. The present invention provides an adhesive film capable of imparting high weather resistance and impact resistance to an OLED display device that does not use a polarizing plate. An adhesive film for an OLED display device, the adhesive film for an OLED display device being used in an OLED display device in which only an optical element having a degree of polarization of 95% or less is laminated on the viewing side of an OLED element, the adhesive film for an OLED display device being characterized in that: the adhesive film for an OLED display device has, as a layer constituting the optical element, at least one layer containing an ultraviolet light absorber; the adhesive film for an OLED display device has an adhesive layer, the adhesive layer has a loss factor (tan [delta]) peak in a region of 0 DEG C or less, the peak top value of the peak is 1.5 or more, and the light transmittance at a wavelength of 380 nm of the adhesive film for an OLED display device is 20% or less.

Description

Technical Field

[0001] The present invention relates to an adhesive film for an OLED display device. More specifically, it relates to an adhesive film used in an OLED display device that does not use a polarizing plate. Background Art

[0002] Compared with a liquid crystal display device, an OLED (organic light emitting diode) display device has advantages in display performance such as high visual recognition, small viewing angle dependence, and fast response speed. In addition, since the OLED display device does not use a backlight, it is advantageous for thinning, and can also be used as a foldable device that can be flexibly bent or folded.

[0003] An OLED display device generally has an OLED element in which an anode, an OLED layer including a light emitting layer, and a cathode are sequentially stacked. Since a transparent conductive material with a high refractive index such as ITO, a metal material with a high reflectivity, etc. are used for the electrodes (anode or cathode) of the OLED element, external light is reflected by the electrodes, resulting in problems such as reduced contrast and internal reflection-induced "mura", and sometimes the display performance of the OLED display device deteriorates. In order to suppress the adverse effects caused by external light reflection, a scheme of arranging a circular polarizing plate such as a polarizing plate and a λ / 4 plate on the visual recognition side of the OLED display device has been proposed (for example, Patent Document 1). Such a circular polarizing plate also has a function of blocking ultraviolet rays contained in external light and preventing deterioration of the OLED element caused by ultraviolet rays. In addition, according to the mechanical properties of the circular polarizing plate itself, it also has the following functions: absorbing external impacts and preventing damage to the OLED display device. However, when using a circular polarizing plate, due to the absorption of the polarizing plate, the light utilization efficiency (i.e., the light collection rate) is poor and the brightness becomes low. When increasing the light emission intensity of the OLED element to obtain the desired brightness, the power consumption increases and the short lifetime of the OLED element is caused. In addition, when the polarizing plate includes an adhesive layer for pasting, the thickness reaches about 0.15 mm, which is not conducive to the thinning of the OLED display device. In addition, since the circular polarizing plate is expensive, there is also a problem that the manufacturing cost becomes high.

[0004] As an alternative to a circularly polarizing plate, the following method has been proposed: for an OLED element, a color filter is disposed on its visually recognizable side, and alignment is performed such that the color filter having the same color as the light emission color of the OLED layer faces the light emitting layer of the OLED, thereby improving the light emission intensity of the OLED element while preventing external light reflection (for example, Patent Document 2). As one form of an OLED display device, an OLED display device having a microcavity (also referred to as multiple reflection interference, an optical resonator, or a microresonator) structure is known. According to the OLED display device having a microcavity structure, the spectrum of the light extracted to the outside becomes steep and has a high intensity, so that the brightness and color purity can be improved (for example, Patent Document 3). In an OLED display device, in order to impart functions such as surface protection and flexibility, various optical element layers such as an adhesive layer, a base material such as plastic or thin glass, and a hard coat are laminated on the visually recognizable side of the OLED element.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2003-332068

[0008] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2018-112715

[0009] Patent Document 3: Japanese Unexamined Patent Application Publication No. 2015-207377 Summary of the Invention

[0010] Problems to be Solved by the Invention

[0011] However, in an OLED display device that does not use such a polarizing plate, there is a problem of low weather resistance of the OLED element. As a reason therefor, it can be cited that, compared with the case of using a polarizing plate, the ultraviolet absorption function of the color filter is insufficient, and thus the OLED element is liable to deteriorate over time due to ultraviolet rays contained in external light.

[0012] In addition, since the polarizing plate has excellent impact resistance, it is possible to impart sufficient impact resistance to the OLED display device. However, in the case of not using a polarizing plate, there is a problem that the impact resistance of the OLED display device becomes insufficient.

[0013] Therefore, an object of the present invention is to provide an adhesive film capable of imparting high weather resistance and impact resistance to an OLED display device that does not use a polarizing plate.

[0014] Means for Solving the Problems

[0015] The inventor of the present invention conducted in-depth research to achieve the above object, and as a result, it was found that in the case of an OLED display device using an adhesive film for an OLED display device having a specific configuration, sufficient weather resistance and impact resistance can be exhibited even when the above OLED display device does not use a polarizing plate, thereby completing the present invention.

[0016] That is, the present invention provides an adhesive film for an OLED display device, which is used for an OLED display device in which only an optical element with a polarization degree of 95% or less is laminated on the visual recognition side of an OLED element. The adhesive film for an OLED display device is characterized in that the adhesive film for an OLED display device has at least one layer containing an ultraviolet absorber as a layer constituting the optical element, the adhesive film for an OLED display device has an adhesive layer, the adhesive layer has a peak of loss factor (tanδ) in a region below 0 °C, and the peak top value is 1.5 or more, and the light transmittance of the adhesive film for an OLED display device at a wavelength of 380 nm is 20% or less.

[0017] The above adhesive layer preferably contains an ultraviolet absorber.

[0018] The above adhesive film preferably further has a resin layer.

[0019] In the present invention, there is also provided an OLED display device in which only an optical element with a polarization degree of 95% or less is laminated on the visual recognition side of an OLED element, and the OLED display device includes the above adhesive film.

[0020] Advantages of the Invention

[0021] The adhesive film of the present invention can impart high weather resistance and impact resistance to an OLED display device that does not use a polarizing plate. Description of the Drawings

[0022] Figure 1 It is a schematic cross-sectional view showing an embodiment of an OLED display panel for an OLED display device used in the present invention.

[0023] Figure 2 It is a schematic cross-sectional view showing an embodiment of the OLED display device of the present invention.

[0024] Figure 3 (a) and Figure 3 (b) are schematic cross-sectional views showing an embodiment of the adhesive film of the present invention. (c) is a schematic cross-sectional view showing an embodiment of an OLED display device using the adhesive film of the present invention.

[0025] Figure 4A graph showing the loss factor (tanδ) of the adhesive layer in the adhesive film according to an embodiment of the present application.

[0026] Figure 5 A schematic diagram of the device for the ball drop test according to an embodiment of the present application.

[0027] Reference numeral description

[0028] 100 OLED display panel

[0029] 10R Red OLED layer

[0030] 10G Green OLED layer

[0031] 10B Blue OLED layer

[0032] 11a Transparent electrode (cathode)

[0033] 11b Back electrode (anode)

[0034] 12R Red OLED element

[0035] 12G Green OLED element

[0036] 12B Blue OLED element

[0037] 13 Substrate

[0038] 14 TFT layer

[0039] 15 Color filter

[0040] 15R Red coloring layer

[0041] 15G Green coloring layer

[0042] 15B Blue coloring layer

[0043] 16 Black matrix layer

[0044] W External light

[0045] G Reflected light

[0046] C1 First optical path (direct light)

[0047] C2 Second optical path (reflected light)

[0048] 17 Bonding layer

[0049] 200 OLED display device

[0050] 20 Optical laminate

[0051] 21 Adhesive layer or adhesive agent layer

[0052] 22 Resin layer, glass layer or shock absorption layer

[0053] 23 Hard coating or antiglare layer

[0054] 24 Adhesive layer or bonding agent layer

[0055] 25 Resin layer, glass layer or shock absorption layer

[0056] 26 Adhesive layer or bonding agent layer

[0057] 27 Resin layer, glass layer or shock absorption layer

[0058] 28 Hard coating or antiglare layer

[0059] 29 Antireflection layer

[0060] 300 Adhesive film with substrate

[0061] 301 Adhesive film

[0062] 302 OLED display device

[0063] 31 Adhesive layer

[0064] 32 Substrate (resin layer)

[0065] 33 Release liner

[0066] X ball drop impact testing machine

[0067] X1 Substrate

[0068] X2 Adhesive layer

[0069] X3 Pressure-sensitive paper

[0070] X4 Iron ball

[0071] X5 Height of the iron ball Detailed implementation mode

[0072] The present invention provides an adhesive film for an OLED display device. Sometimes, the adhesive film for an OLED display device of the present invention is referred to as "the adhesive film of the present invention". In addition, the present invention provides an OLED display device having an optical laminate including the above-mentioned adhesive film. The optical laminate is a laminate obtained by removing the OLED display panel from the OLED display device of the present invention and includes the adhesive film of the present invention. The optical laminate is composed of optical elements.

[0073] In the OLED display device of the present invention, in the OLED display panel, only optical elements with a polarization degree of 95% or less are stacked on the visual recognition side of the OLED element. "Only optical elements with a polarization degree of 95% or less are stacked on the visual recognition side of the OLED element" means that the optical elements on the visual recognition side of the OLED element do not include optical elements with a polarization degree greater than 95%. There are no particular limitations on the "optical elements with a polarization degree greater than 95%", including polarizing plates such as linear polarizing plates, quarter-wave plates, half-wave plates, circular polarizing plates, and reflective polarizing plates. That is, the OLED display device of the present invention can be described as an OLED display device that does not include a polarizing plate on the visual recognition side of the OLED element. The polarization degree is a value obtained by the following formula based on the parallel transmittance Tp and the orthogonal transmittance Tc measured using an ultraviolet-visible spectrophotometer and corrected for visibility.

[0074] Polarization degree (%) = {(Tp - Tc) / (Tp + Tc)} 1 / 2 × 100

[0075] Since the OLED display device of the present invention does not include a polarizing plate on the visual recognition side of the OLED element, it is possible to suppress the absorption of light emitted from the OLED element by the polarizing plate, improve the light collection rate, save power consumption, and contribute to the long life of the OLED element. In addition, by not using a polarizing plate, it is possible to achieve thinning and reduce the manufacturing cost.

[0076] The adhesive film of the present invention is characterized in that it has at least one layer containing an ultraviolet absorber as a layer constituting an optical element in the OLED display device, and has an adhesive layer, and the adhesive layer has a peak of tanδ in a region below 0 °C, and the peak top value is 1.5 or more, and the light transmittance at a wavelength of 380 nm is 20% or less. The adhesive film of the present invention having the above characteristics is suitable for improving the weather resistance and impact resistance in the OLED display device.

[0077] The adhesive film of the present invention at least includes an adhesive layer. The above adhesive layer may be a layer containing an ultraviolet absorber. In addition to the adhesive layer, the adhesive film of the present invention may have a resin layer, and the resin layer may be a layer containing an ultraviolet absorber. When the adhesive film of the present invention has a resin layer, it is preferable from the viewpoint of improving the impact resistance. In addition, the adhesive film of the present invention may have an optical element other than the above adhesive layer and resin layer to be stacked on the OLED display device of the present invention as a constituent of the adhesive film. In the adhesive film of the present invention, at least one layer of the adhesive layer may be a high refractive index adhesive layer, or all may be high refractive index adhesive layers.

[0078] There are no particular limitations on the moisture permeability of the adhesive film of the present invention. For example, it is preferably 5000 g / m 2·Less than 24 hours, more preferably 3500 g / m 2 ·Less than 24 hours, more preferably 2000 g / m 2 ·Less than 24 hours, more preferably 1000 g / m 2 ·Less than 24 hours, more preferably 500 g / m 2 ·Less than 24 hours, more preferably 200 g / m 2 ·Less than 24 hours, further preferably 100 g / m 2 ·Less than 24 hours, particularly preferably 80 g / m 2 ·Less than 24 hours. The lower limit value of the water vapor transmission rate is not particularly limited, and from the viewpoint of suppressing humidification swelling, it is 10 g / m 2 ·24 hours. The water vapor transmission rate of the adhesive film of the present invention is within the above range, and has a tendency to suppress deterioration of the panel caused by moisture. The water vapor transmission rate of the adhesive film of the present invention can be measured according to JIS Z0208 in an environment of a temperature of 40°C and a relative humidity of 92%, and can be adjusted by the type, thickness, etc. of the resin constituting the adhesive film of the present invention.

[0079] The light transmittance of the adhesive film of the present invention at a wavelength of 380 nm is not particularly limited as long as it is 20% or less, preferably 15% or less, more preferably 10% or less, more preferably 7% or less, more preferably 5% or less, more preferably 4% or less, more preferably 3% or less, further preferably 2% or less, particularly preferably 1% or less. The lower limit of the light transmittance at a wavelength of 380 nm is 0%. It should be noted that the method for measuring the light transmittance at a wavelength of 380 nm is not particularly limited, and for example, it can be measured by using a spectrophotometer U4100 (manufactured by Hitachi High-Technologies Corporation). It should be noted that the light transmittance at wavelengths other than 380 nm can also be measured by the above device.

[0080] The light transmittance of the adhesive film of the present invention at a wavelength of 450 nm is not particularly limited, and for example, it is preferably 20% or less, more preferably 15% or less, more preferably 10% or less, more preferably 7% or less, further preferably 5% or less, particularly preferably 4% or less. The lower limit of the light transmittance at a wavelength of 450 nm is 0%.

[0081] After exposure to an environment of 85°C and 85% relative humidity for 240 hours, the variation ratio of the light transmittance at a wavelength of 380 nm of the adhesive film of the present invention (hereinafter sometimes referred to as "the variation ratio of the light transmittance at a wavelength of 380 nm after humidification") is not particularly limited as long as it is 0.9 to 1.2, preferably 0.95 to 1.2, more preferably 1 to 1.19, and further preferably 1.07 to 1.19. By keeping the variation ratio of the light transmittance within the above range, even in the presence of high temperature and high humidity, it is possible to prevent the ultraviolet rays contained in the external light from deteriorating over time for a long time.

[0082] The change ratio of the light transmittance at a wavelength of 380 nm after the humidification can be calculated by the following formula.

[0083] Change ratio of light transmittance at a wavelength of 380 nm after humidification = (light transmittance at a wavelength of 380 nm after humidification) / (light transmittance at an initial wavelength of 380 nm)

[0084] In the adhesive film of the present invention, the method for adjusting the transmittance and the variation ratio of the transmittance at a specific wavelength (e.g., 380 nm, etc.) is not particularly limited, and can be adjusted, for example, by the composition of the layer constituting the optical element, specifically, by the type, monomer composition, crosslinking degree, and thickness of the adhesive constituting the adhesive layer. In particular, the transmittance can be adjusted by using the acrylic adhesive composition described later as the adhesive constituting the adhesive layer, or by containing an ultraviolet absorber.

[0085] In the adhesive film of the present invention, the impact force (N) in the drop ball test is not particularly limited, and is preferably 1500 N or less, more preferably 1400 N or less, and further preferably 1300 N or less. The lower limit of the impact force (N) is not particularly limited, and is preferably 100 N, and more preferably 500 N. It should be noted that the impact force (N) in the drop ball test can be measured, for example, by the method described in the examples.

[0086] The thickness of the adhesive film of the present invention is not particularly limited, but is, for example, preferably 10 μm to 2 mm, more preferably 15 μm to 1 mm, further preferably 20 μm to 500 μm, and particularly preferably 20 μm to 200 μm.

[0087] It should be noted that, in this specification, "adhesive film" includes the meaning of "adhesive sheet" and "adhesive tape". That is, the adhesive film of the present invention may be an adhesive sheet or adhesive tape having a sheet-like or tape-like form. The adhesive film of the present invention is an element for forming an optical laminate, and may include the above-mentioned high refractive index adhesive layer.

[0088] The adhesive film of the present invention can be a so-called "substrate-free type" adhesive film without a substrate (equivalent to the "resin layer" described later), or can be an adhesive film with a substrate. It should be noted that in this specification, the "substrate-free type" adhesive film is sometimes referred to as a "substrate-free adhesive film", and the adhesive film with a substrate is sometimes referred to as a "substrate-bearing adhesive film". As the above-mentioned substrate-free adhesive film, for example, a double-sided adhesive sheet containing only an adhesive layer can be cited. The adhesive layer in the above double-sided adhesive sheet can be composed of one layer or a multi-layer structure of two or more layers. As the above-mentioned substrate-bearing adhesive film, for example, a single-sided adhesive film having an adhesive layer on one side of the substrate, a double-sided adhesive film having adhesive layers on both sides of the substrate, etc. can be cited. The adhesive layer in the above single-sided adhesive film can be composed of one layer or a multi-layer structure of two or more layers. In addition, the two adhesive layers can be formed continuously or independently (i.e., with other layers in between). One adhesive layer in the above double-sided adhesive film can be composed of one layer or a multi-layer structure of two or more layers. In addition, the two adhesive layers can be formed continuously or independently (i.e., with other layers in between). In addition, the other adhesive layer can be composed of one layer or a multi-layer structure of two or more layers. In addition, the two adhesive layers can be formed continuously or independently (i.e., with other layers in between). The above-mentioned "substrate" refers to a support, which is the part that is pasted to the adherend together with the adhesive layer when the adhesive film of the present invention is used (pasted) to the adherend. The release liner peeled off when using (pasting) the adhesive film is not included in the above substrate.

[0089] Hereinafter, each component of the adhesive film of the present invention will be described.

[0090] (OLED display panel)

[0091] The OLED display panel for an OLED display device of the present invention includes an OLED element in which an anode, an OLED layer including a light-emitting layer, and a cathode are sequentially stacked as an essential component. An optical laminate is stacked on the visual recognition side of the OLED element of the OLED display panel.

[0092] Hereinafter, an embodiment of the OLED display panel constituting the OLED display device of the present invention will be described with reference to the drawings, but the present invention is not limited to this embodiment.

[0093] Figure 1 It is a schematic cross-sectional view showing an embodiment of the OLED display panel.

[0094] As Figure 1As shown, the OLED display panel 100 has: a red OLED element 12R in which a transparent electrode 11a, a red OLED layer 10R that emits red light, and a back electrode 11b are stacked in sequence; a green OLED element 12G in which a transparent electrode 11a, a green OLED layer 10G that emits green light, and a back electrode 11b are stacked in sequence; and a blue OLED element 12B in which a transparent electrode 11a, a blue OLED layer 10B that emits blue light, and a back electrode 11b are stacked in sequence. Each of the OLED elements 12R, 12G, 12B of various colors is disposed on the substrate 13 in order. A TFT (thin film transistor) layer 14 is formed on the surface of the substrate 13 where each of the OLED elements is disposed, and is connected to the back electrodes 11b of each of the OLED elements 12R, 12G, 12B of various colors.

[0095] In Figure 1 the OLED display panel 100, a color filter 15 is disposed on the visual recognition side ( Figure 1 the upper side in ) of each of the OLED elements 12R, 12G, 12B of various colors. The color filter 15 includes a red coloring layer 15R, a green coloring layer 15G, and a blue coloring layer 15B, and a black matrix layer 16 is provided between the coloring layers.

[0096] In Figure 1 it, the color filter 15 is disposed in such a manner that the red coloring layer 15R, the green coloring layer 15G, and the blue coloring layer 15B face the red OLED element 12R, the green OLED element 12G, and the blue OLED element 12B, respectively.

[0097] The transparent electrode 11a is either a cathode or an anode, but is usually set as a cathode. As a material for forming the transparent electrode 11a, transparent conductive materials such as ITO (indium tin oxide), indium oxide, IZO (indium zinc oxide), SnO2, and ZnO are used.

[0098] The back electrode 11b functions as a counter electrode to the transparent electrode 11a. The back electrode 11b is either an anode or a cathode, but is usually set as an anode on the substrate 13. As materials for forming it, metals such as gold, silver, and chromium can be cited, etc. Therefore, the back electrode 11b can reflect light.

[0099] A bonding layer 17 is provided between the substrate 13 and the color filter 15. The bonding layer 17 has light transmissivity. As a material for the bonding layer 17, materials used in ordinary OLED display devices can be used. For example, photocurable resins such as photosensitive polyimide resins, or thermosetting resins, etc. can be used.

[0100] The OLED display panel 100 in addition to Figure 1In addition to the structure shown, it may also have the structure of an OLED display panel, such as a hole injection layer, a hole transport layer, an electron transport layer, a sealing layer, a touch sensor panel, etc. (illustrations are omitted).

[0101] Figure 1 The OLED display panel is characterized in that color filters 15 are respectively arranged on the OLED elements 12R, 12G, and 12B of various colors in a manner opposite to the color layers 15R, color layer 15G, and color layer 15B of the same color. As Figure 1 shown, the white external light W passes through the red color layer 15R, for example, further passes through the transparent electrode 11a and the red OLED layer 10R that emits red light, and is reflected at the back electrode 11b, and then passes through the red OLED layer 10R, the transparent electrode 11a, and the red color layer 15R again, and then the reflected light G enters the observer's eyes.

[0102] The external light W is absorbed by the red color layer 15R for green and blue, so the light intensity becomes 1 / 3. In addition, the reflected light G passes through the red color layer 15R and the red OLED layer 10R again, resulting in attenuation. In addition, the reflected light G is red, so the red light emitted from the OLED layer 10R can be enhanced. The same is true when the external light W is incident on the green color layer 15G and the blue color layer 15B, and the green light and the blue light can be enhanced respectively. Therefore, by using color filters in the OLED display panel, even without using a polarizing plate to prevent reflection, the reflection of external light can be greatly suppressed, and the light emission intensity of the OLED element can be improved.

[0103] However, color filters are usually prone to interference unevenness caused by a regular two-dimensional structure. In addition, there is a problem that color filters are prone to reflection at the interface, and the light collection rate of the light emitted from the OLED element is reduced. In addition, in color filters, compared with the case of using a polarizing plate, there is a problem that the ultraviolet absorption function is insufficient, and the OLED element is prone to deterioration over time due to the ultraviolet rays contained in the external light (that is, the weather resistance is low). In addition, compared with the case of using a polarizing plate, color filters have a problem of insufficient shock absorption function.

[0104] In addition, the OLED display panel 100 of the present embodiment has a microcavity structure. The light generated from the OLED layers 10R, 10G, and 10B is emitted to the outside through the transparent electrode 11a. Here, the emitted light includes two components: "direct light" that is directly emitted from the OLED layers 10R, 10G, and 10B toward the transparent electrode 11a, and "reflected light" that is emitted from the OLED layers 10R, 10G, and 10B toward the back electrode 11b and then reflected by the back electrode 11b and directed toward the transparent electrode 11a. That is, a first optical path C1 is formed in which a part of the light emitted from the OLED layers 10R, 10G, and 10B does not travel toward the back electrode 11b side but travels toward the transparent electrode 11a side and is emitted to the outside through the transparent electrode 11a, and a second optical path C2 is formed in which the remaining part of the light emitted from the OLED layers 10R, 10G, and 10B travels toward the back electrode 11b side, is reflected by the back electrode 11b, and then is emitted to the outside through the OLED layers 10R, 10G, and 10B and the transparent electrode 11a. The thicknesses of the OLED layers 10R, 10G, and 10B are different from each other to enhance the light components corresponding to each color through the interference of the direct light and the reflected light. That is, the thicknesses of the OLED layers 10R, 10G, and 10B are different from each other so that the optical path length between the back electrode (positive electrode) 11b and the transparent electrode (negative electrode) 11a coincides with the peak wavelengths of the EL spectra of red, green, and blue, respectively, thereby extracting the strongest light from each color. Specifically, the thickness of the short-wavelength blue OLED layer 10B is designed to be relatively thin, and the thickness of the long-wavelength red OLED layer 10R is designed to be relatively thick. When the light generated in the OLED layer is repeatedly reflected between the positive electrode and the negative electrode, only the light of the wavelength with the same optical path length resonates and is strengthened, and the light of the other wavelengths with deviated optical path lengths is weakened. As a result, the spectrum of the light extracted to the outside becomes steep and has a high intensity, and the brightness and color purity are improved.

[0105] According to the OLED display panel having a microcavity structure, excellent effects of improved brightness and color purity can be obtained. On the other hand, due to the steep spectrum, there may be a problem of strong viewing angle dependence (narrow viewing angle). Therefore, when observing an image from an inclined direction during image display, color shift may sometimes occur, where the color appears different from the color originally intended to be displayed.

[0106] (Optical element)

[0107] The optical element is an optical element laminated on the visual recognition side of the OLED display device and includes at least an adhesive layer. The above optical element may further include at least one layer selected from an adhesive layer, a resin layer, a glass layer, a hard coat layer, an antireflection layer, an antiglare layer, an intermediate layer (compatibilizing layer), a shock absorption layer, an antistatic layer, etc. However, the optical element does not include an optical element with a polarization degree greater than 95% such as a polarizing plate.

[0108] (Adhesive layer)

[0109] The adhesive layer refers to a layer that has adhesiveness at room temperature and adheres to the adherend with a light pressure, and is a layer that maintains a practical adhesive force even when the adherend adhered to the adhesive layer is peeled off.

[0110] From the viewpoint of preventing interface reflection and improving the light collection rate of the light emitted from the OLED element, the adhesive layer constituting the optical element is preferably a high refractive index. The refractive index of the adhesive layer is preferably 1.57 or more, more preferably 1.575 or more, further preferably 1.580 or more, particularly preferably 1.585 or more, still further preferably 1.590 or more, and may be 1.595 or more.

[0111] The refractive index of the adhesive layer can be adjusted, for example, by the types and contents of the aromatic ring-containing monomers, high refractive index organic materials, and high refractive index inorganic materials described later.

[0112] The adhesive layer is not particularly limited, and from the viewpoint of effectively reducing color shift and interference unevenness of the OLED display device, it preferably has a light scattering property (function of scattering light).

[0113] When the OLED display device includes a color filter on the visual recognition side, from the viewpoints of reducing color shift and interference unevenness of the OLED display device and suppressing image blurring of the OLED display device caused by light scattering, the distance between the adhesive layer and the color filter is preferably 700 μm or less, more preferably 600 μm or less, further preferably 500 μm or less, and most preferably 0 μm, that is, the adhesive layer is in direct contact with the color filter.

[0114] The distance between the adhesive layer and the color filter represents the distance (μm) between the surface of the adhesive layer in the direction of the color filter and the surface of the color filter in the direction of the adhesive layer. When other layers are laminated between the adhesive layer and the color filter, it corresponds to the thickness (μm) of the other layer (the total thereof in the case of two or more layers).

[0115] The haze value of the adhesive layer is not particularly limited. From the viewpoint of effectively reducing color shift and interference unevenness of the OLED display device, it is preferably 20% or more, more preferably 30% or more, further preferably 40% or more, and particularly preferably 50% or more. In addition, from the viewpoint of suppressing image blurring of the OLED display device and displaying a high-definition image, the haze value of the adhesive layer is preferably 90% or less, more preferably 80% or less, and further preferably 70% or less.

[0116] The total light transmittance of the adhesive layer is not particularly limited. From the viewpoint of ensuring the brightness of the OLED display device, it is preferably 60% or more, more preferably 70% or more, further preferably 80% or more, and particularly preferably 90% or more. In addition, the upper limit value of the total light transmittance of the adhesive layer is not particularly limited, and it may be less than 100%, or may be 99.9% or less or 99% or less.

[0117] The haze value and the total light transmittance of the adhesive layer can be measured by the methods specified in JIS7136 and JIS7361, respectively, and can be controlled by the type of the adhesive layer, the thickness, the type of the light-scattering particles described later, the compounding amount, etc.

[0118] The adhesive layer has a peak of the loss factor (tanδ) in the region below 0°C, and the peak top value is 1.5 or more. The above loss factor is more preferably 1.8 or more, further preferably 2.0 or more, and particularly preferably 2.2 or more. The maximum value of the above loss factor is not particularly limited, and for example, it is preferably 5.0, more preferably 3.0. It should be noted that in the case where the adhesive layer includes an adhesive layer having two or more continuous layers, the loss factor (tanδ) of the adhesive layer is measured by regarding the two or more adhesive layers as one adhesive layer. By the loss factor of the above adhesive layer being within the above range, there is a tendency for the impact resistance to be improved.

[0119] The thickness of the adhesive layer is not particularly limited. From the viewpoint of improving the impact resistance, it is preferably 10 μm to 500 μm, more preferably 15 μm to 300 μm, further preferably 15 μm to 200 μm, further preferably 20 μm to 100 μm, and particularly preferably 20 μm to 40 μm. It should be noted that in the case where the adhesive layer includes two or more adhesive layers, the thickness of the adhesive layer is the total thickness of the two or more adhesive layers.

[0120] The adhesive constituting the adhesive layer is not particularly limited, and examples thereof include acrylic adhesives, rubber adhesives, vinyl alkyl ether adhesives, polysiloxane adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, fluorine-containing adhesives, epoxy adhesives, etc. Among them, as the adhesive constituting the adhesive layer, from the viewpoints of transparency, adhesiveness, weather resistance, cost, and ease of design of the adhesive, acrylic adhesives are preferred. That is, the adhesive layer is preferably an acrylic adhesive layer composed of an acrylic adhesive. The above adhesives can be used alone or in combination of two or more.

[0121] The acrylic adhesive layer contains an acrylic polymer as a base polymer. The acrylic polymer is a polymer containing acrylic monomers (monomers having a (meth)acryloyl group in the molecule) as monomer components constituting the polymer. The acrylic polymer is preferably a polymer containing an alkyl (meth)acrylate as a monomer component constituting the polymer. It should be noted that the acrylic polymer can be used alone or in combination of two or more.

[0122] The adhesive composition for forming the adhesive layer can be in any form. For example, the adhesive composition can be an emulsion type, a solvent type (solution type), an active energy ray curable type, a hot melt type (hot melt type), etc. Among them, from the aspect of productivity and the aspect of easily obtaining an adhesive layer with excellent optical properties and appearance properties, a solvent type or an active energy ray curable type adhesive composition is preferred. That is, the adhesive layer is an acrylic adhesive layer containing an acrylic polymer as a base polymer, and is preferably formed from a solvent type or an active energy ray curable type acrylic adhesive composition.

[0123] Examples of the adhesive composition (acrylic adhesive composition) for forming the acrylic adhesive layer include: an acrylic adhesive composition having an acrylic polymer as an essential component, or an acrylic adhesive composition having a mixture of monomers (monomers) constituting the acrylic polymer (sometimes referred to as a "monomer mixture") or a partial polymer thereof as an essential component, etc. As the former, for example, a so-called solvent type acrylic adhesive composition can be cited. In addition, as the latter, for example, a so-called active energy ray curable type acrylic adhesive composition can be cited. The above "monomer mixture" refers to a mixture containing monomer components constituting the polymer. In addition, the above "partial polymer" is sometimes also referred to as a "prepolymer", and refers to a composition obtained by partially polymerizing one or two or more of the monomer components in the above monomer mixture.

[0124] The acrylic polymer is a polymer formed (constituted) with acrylic monomers as essential monomer components (monomer components). The acrylic polymer is preferably a polymer formed (constituted) with an alkyl (meth)acrylate as an essential monomer component. That is, the acrylic polymer preferably contains an alkyl (meth)acrylate as a structural unit. In this specification, "(meth)acrylic acid" means "acrylic acid" and / or "methacrylic acid" (either one or both of "acrylic acid" and "methacrylic acid"), and the same applies to others. It should be noted that the above acrylic polymer is composed of one or two or more monomer components.

[0125] As the above-mentioned (meth)acrylic acid alkyl ester which is an essential monomer component, preferably, (meth)acrylic acid alkyl esters having a linear or branched alkyl group can be mentioned. It should be noted that the (meth)acrylic acid alkyl esters can be used alone or in combination of two or more.

[0126] As the (meth)acrylic acid alkyl ester having a linear or branched alkyl group, there is no particular limitation. For example, (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid propyl ester, (meth)acrylic acid isopropyl ester, (meth)acrylic acid n-butyl ester, (meth)acrylic acid isobutyl ester, (meth)acrylic acid sec-butyl ester, (meth)acrylic acid tert-butyl ester, (meth)acrylic acid pentyl ester, (meth)acrylic acid hexyl ester, (meth)acrylic acid 2-ethylhexyl ester and the like, which are (meth)acrylic acid alkyl esters having a linear or branched alkyl group with 1 to 20 carbon atoms can be mentioned. Among them, the above-mentioned (meth)acrylic acid alkyl ester having a linear or branched alkyl group preferably has a (meth)acrylic acid alkyl ester having a linear or branched alkyl group with 4 to 18 carbon atoms, and more preferably butyl acrylate. The above-mentioned (meth)acrylic acid alkyl ester having a linear or branched alkyl group can be used alone or in combination of two or more.

[0127] The proportion of the above-mentioned (meth)acrylic acid alkyl ester in all monomer components (100% by weight) of the above-mentioned acrylic polymer is not particularly limited, and is preferably 50% by weight or more (for example, 50% by weight to 100% by weight), more preferably 60% by weight to 99.5% by weight, and further preferably 70% by weight to 99% by weight.

[0128] The above-mentioned acrylic polymer can contain a copolymerizable monomer together with the above-mentioned (meth)acrylic acid alkyl ester as a monomer component constituting the polymer. That is, the above-mentioned acrylic polymer can contain a copolymerizable monomer as a structural unit. It should be noted that the copolymerizable monomer can be used alone or in combination of two or more.

[0129] As the above-mentioned copolymerizable monomer, there is no particular limitation. By using a monomer having an aromatic ring in the molecule, an adhesive layer with a high refractive index can be obtained, the interfacial reflection with the OLED display panel can be suppressed, and the light collection rate of the light emitted from the OLED element can be improved. The above-mentioned monomer having an aromatic ring in the molecule is a monomer (monomer) having at least one aromatic ring in the molecule (within one molecule). In this specification, the "monomer having an aromatic ring in the molecule" is sometimes referred to as an "aromatic ring-containing monomer".

[0130] As the aromatic ring-containing monomer, a compound containing at least one aromatic ring and at least one ethylenically unsaturated group in one molecule is used. As the aromatic ring-containing monomer, one of the above compounds may be used alone or two or more thereof may be used in combination. Examples of the above ethylenically unsaturated group include: (meth)acryloyl group, vinyl group, (meth)allyl group, etc. From the viewpoint of polymerization reactivity, the (meth)acryloyl group is preferred, and from the viewpoints of flexibility and adhesiveness, the acryloyl group is more preferred. From the viewpoint of suppressing the reduction in the flexibility of the adhesive, as the aromatic ring-containing monomer, a compound having 1 ethylenically unsaturated group in one molecule (i.e., a monofunctional monomer) is preferably used.

[0131] There is no particular limitation on the above copolymerizable monomer. From the viewpoints of suppressing clouding in a high-humidity environment, improving durability, compatibility with various additives such as ultraviolet absorbers, and transparency, preferred examples include: monomers having a nitrogen atom in the molecule, monomers having a hydroxyl group in the molecule.

[0132] The above monomer having a nitrogen atom in the molecule is a monomer (single molecule) having at least one nitrogen atom in the molecule (in one molecule). In this specification, the "monomer having a nitrogen atom in the molecule" is sometimes referred to as the "nitrogen atom-containing monomer". There is no particular limitation on the above nitrogen atom-containing monomer, and preferred examples include: cyclic nitrogen-containing monomers, (meth)acrylamides, etc. It should be noted that the nitrogen atom-containing monomers may be used alone or in combination of two or more.

[0133] The above cyclic nitrogen-containing monomer is not particularly limited as long as it has a polymerizable functional group having an unsaturated double bond such as (meth)acryloyl group or vinyl group and has a cyclic nitrogen structure. The above cyclic nitrogen structure preferably has a nitrogen atom in the cyclic structure. Examples of the above cyclic nitrogen-containing monomer include: N-vinyl cyclic amide (vinyl monomer of lactam), vinyl monomers having a nitrogen-containing heterocycle, etc.

[0134] The above monomer having a hydroxyl group in the molecule is a monomer having at least one hydroxyl group (hydroxyl group) in the molecule (in one molecule), and preferred examples include: monomers having a polymerizable functional group having an unsaturated double bond such as (meth)acryloyl group or vinyl group and having a hydroxyl group. However, the above nitrogen atom-containing monomer is not included in the monomer having a hydroxyl group in the molecule. That is, in this specification, a monomer having both a nitrogen atom and a hydroxyl group in the molecule is included in the above "nitrogen atom-containing monomer". In this specification, the above "monomer having a hydroxyl group in the molecule" is sometimes referred to as the "hydroxyl group-containing monomer". It should be noted that the hydroxyl group-containing monomers may be used alone or in combination of two or more.

[0135] As the above-mentioned hydroxyl group-containing monomers, for example, the following can be cited: hydroxyl group-containing (meth)acrylic acid esters such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate; vinyl alcohol; allyl alcohol and the like. Among them, as the above-mentioned hydroxyl group-containing monomers, hydroxyl group-containing (meth)acrylic acid esters are preferred, and 2-hydroxyethyl acrylate (HEA) and 4-hydroxybutyl acrylate (4HBA) are more preferred.

[0136] When the acrylic polymer contains the hydroxyl group-containing monomer as a monomer component constituting the polymer, the proportion of the hydroxyl group-containing monomer in all the monomer components (100% by weight) constituting the acrylic polymer is not particularly limited. From the viewpoints of suppressing clouding in a high-humidity environment and improving durability, it is preferably 0.001% by weight to 5% by weight, more preferably 0.01% by weight to 3% by weight, and still more preferably 0.03% by weight to 1% by weight.

[0137] As copolymerizable monomers other than nitrogen atom-containing monomers and hydroxyl group-containing monomers, alicyclic structure-containing monomers, polyfunctional monomers, (meth)acrylic acid alkoxyalkyl esters, carboxyl group-containing monomers, epoxy group-containing monomers, etc. can be cited. As the above-mentioned carboxyl group-containing monomers, for example, the following can be cited: (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, and acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride.

[0138] When the acrylic polymer contains the carboxyl group-containing monomer as a monomer component constituting the polymer, the proportion of the carboxyl group-containing monomer in all the monomer components (100% by weight) constituting the acrylic polymer is not particularly limited, and it is preferably 0.1% by weight to 30% by weight, more preferably 0.5% by weight to 20% by weight.

[0139] The content of the base polymer (especially acrylic polymer) in the adhesive layer is not particularly limited. Relative to 100% by weight of the total weight of the adhesive layer, it is preferably 50% by weight or more (for example, 50% by weight to 100% by weight), more preferably 80% by weight or more (for example, 80% by weight to 100% by weight), and still more preferably 90% by weight or more (for example, 90% by weight to 100% by weight).

[0140] The above-mentioned base polymers such as acrylic polymers contained in the adhesive layer are obtained by polymerizing monomer components. As the polymerization method, there is no particular limitation, and for example, the following can be cited: solution polymerization method, emulsion polymerization method, bulk polymerization method, polymerization method using active energy ray irradiation (active energy ray polymerization method), etc.

[0141] When polymerizing the above monomer components, polymerization initiators such as solvents, thermal polymerization initiators, and photopolymerization initiators (photoinitiators) can be used according to the type of polymerization reaction. It should be noted that the polymerization initiators can be used alone or in combination of two or more.

[0142] As the above thermal polymerization initiator, there is no particular limitation. For example, azo polymerization initiators, peroxide polymerization initiators (such as benzoyl peroxide, tert-butyl peroxymaleate, etc.), redox polymerization initiators, etc. can be cited. Among them, azo polymerization initiators disclosed in Japanese Patent Application Laid-Open No. 2002-69411 are preferred. As the above azo polymerization initiators, 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), dimethyl 2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), etc. can be cited. It should be noted that the thermal polymerization initiators can be used alone or in combination of two or more.

[0143] When using the above azo polymerization initiator during the polymerization of the above acrylic polymer, the amount of use of the above azo polymerization initiator is not particularly limited. For example, relative to 100 parts by weight of all monomer components constituting the above acrylic polymer, it is preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more. In addition, the amount of use of the above azo polymerization initiator is preferably 0.5 parts by weight or less, more preferably 0.3 parts by weight or less.

[0144] As the above photopolymerization initiator, there is no particular limitation. For example, benzoin ether photopolymerization initiators, acetophenone photopolymerization initiators, α-ketol photopolymerization initiators, aromatic sulfonyl chloride photopolymerization initiators, etc. can be cited. The photopolymerization initiators can be used alone or in combination of two or more.

[0145] When using the above photopolymerization initiator during the polymerization of the above acrylic polymer, the amount of use of the above photopolymerization initiator is not particularly limited. For example, relative to 100 parts by weight of all monomer components constituting the above acrylic polymer, the amount of use of the photopolymerization initiator is preferably 0.01 parts by weight or more, more preferably 0.1 parts by weight or more. In addition, the amount of use of the photopolymerization initiator is preferably 3 parts by weight or less, more preferably 1.5 parts by weight or less.

[0146] The adhesive layer may contain an ultraviolet absorber (UVA). When the adhesive layer contains an ultraviolet absorber, deterioration of the OLED element caused by ultraviolet rays contained in external light can be suppressed, and an OLED display device with excellent weather resistance can be obtained even without using a polarizing plate. In addition, deterioration of the high refractive index component caused by ultraviolet rays can be suppressed, and high light transmittance can be maintained. It should be noted that the ultraviolet absorbers can be used alone or in combination of two or more.

[0147] As the above-mentioned ultraviolet absorber, there is no particular limitation. For example, it may include: benzotriazole ultraviolet absorbers, hydroxyphenyltriazine ultraviolet absorbers, benzophenone ultraviolet absorbers, salicylate ultraviolet absorbers, cyanoacrylate ultraviolet absorbers, hydroxydibenzophenone ultraviolet absorbers, etc. As the above-mentioned ultraviolet absorber, from the viewpoints of having high ultraviolet absorbability, obtaining an adhesive layer having excellent optical properties and high transparency, and having excellent light stability, it is preferably at least one ultraviolet absorber selected from benzotriazole ultraviolet absorbers, hydroxyphenyltriazine ultraviolet absorbers, and benzophenone ultraviolet absorbers.

[0148] As the benzotriazole ultraviolet absorber (benzotriazole compound), for example, it may include: 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole, phenylpropionic acid, and an ester compound of 3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy (C 7-9 side-chain and straight-chain alkyl), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, etc.

[0149] As the hydroxyphenyltriazine ultraviolet absorber (hydroxyphenyltriazine compound), for example, it may include: the reaction product of 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-hydroxyphenyl and [(C 10-16 (mainly C 12-13 ) alkoxy)methyl]oxirane, 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-[3-(dodecyloxy)-2-hydroxypropoxy]phenol), 2,4-bis-[{4-(4-ethylhexyloxy)-4-hydroxy}-phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine, etc.

[0150] As the benzophenone ultraviolet absorber (benzophenone compound) and hydroxydibenzophenone ultraviolet absorber (hydroxydibenzophenone compound), for example, it may include: 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (anhydride and trihydrate), 2-hydroxy-4-octyloxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, etc.

[0151] When the adhesive layer contains an ultraviolet absorber, the content of the ultraviolet absorber in the adhesive layer (particularly an acrylic adhesive layer) is not particularly limited. From the viewpoint of suppressing the deterioration of the OLED element caused by ultraviolet rays contained in external light and obtaining an OLED display device with excellent weather resistance even without using a polarizing plate, it is preferably 0.01 part by weight or more, more preferably 0.05 part by weight or more, and further preferably 0.1 part by weight or more, relative to 100 parts by weight of the base polymer (e.g., acrylic polymer). In addition, from the viewpoint of suppressing the occurrence of yellowing of the adhesive accompanying the addition of the ultraviolet absorber and obtaining excellent optical properties, high transparency, and excellent appearance properties, the upper limit of the content of the ultraviolet absorber is preferably 20 parts by weight or less, more preferably 10 parts by weight or less, and further preferably 8 parts by weight or less, relative to 100 parts by weight of the acrylic polymer.

[0152] The adhesive layer may contain a pigment compound (e.g., a pigment compound having a maximum absorption wavelength of the absorption spectrum in the wavelength range of 380 nm to 430 nm) instead of the ultraviolet absorber or in combination with the ultraviolet absorber. By the pigment compound, it is possible to suppress the deterioration of the OLED element and the deterioration of the high refractive index component caused by ultraviolet light.

[0153] The above pigment compounds may be used alone or in combination of two or more. When only the above pigment compounds are used, the total content of the pigment compounds is preferably 0.005 part by weight or more, more preferably 0.01 part by weight or more, more preferably 0.05 part by weight or more, further preferably 0.1 part by weight or more, and particularly preferably 0.2 part by weight or more, relative to 100 parts by weight of the base polymer (e.g., acrylic polymer). In addition, it is preferably 20 parts by weight or less, more preferably 15 parts by weight or less, more preferably 10 parts by weight or less, further preferably 5 parts by weight or less, and particularly preferably 2 parts by weight or less, relative to 100 parts by weight of the acrylic polymer. By making the addition amount of the pigment compound within the above range, it is possible to sufficiently absorb the light in the region that does not affect the light emission of the OLED element. By using the adhesive layer formed from this adhesive composition, it is possible to suppress the deterioration of the OLED element and the deterioration of the high refractive index component, and thus it is preferred.

[0154] Either the ultraviolet absorber or the pigment compound can be used, and preferably, the ultraviolet absorber and the pigment compound are used in combination. Depending on the ultraviolet absorber, for example, although light with a wavelength of 380 nm can be absorbed, light in the wavelength region on the shorter wavelength side (380 nm to 430 nm) than the light emission region of the OLED element (the wavelength side longer than 430 nm) cannot be sufficiently absorbed, and sometimes deterioration may occur due to this transmitted light. The above pigment compound can suppress the transmission of light with a wavelength on the shorter wavelength side (380 nm to 430 nm) than the light emission region of the OLED element. By using the above ultraviolet absorber and pigment compound in combination, the transmittance of visible light in the light emission region of the above OLED element can be sufficiently ensured.

[0155] In the present invention, by using such a pigment compound and an ultraviolet absorber in combination, light in the region (wavelength 380 nm to 430 nm) that does not affect the light emission of the OLED element can be sufficiently absorbed, and the light emission region of the OLED element (the wavelength side longer than 430 nm) can be sufficiently transmitted. As a result, deterioration of the OLED element caused by external light and deterioration of the high refractive index component can be suppressed simultaneously. When the ultraviolet absorber and the pigment compound are used in combination, with respect to 100 parts by weight of the base polymer (for example, an acrylic polymer), the ultraviolet absorber is preferably 0.1 part by weight to 10 parts by weight, more preferably 0.1 part by weight to 5 parts by weight, and still more preferably 0.5 part by weight to 3 parts by weight. With respect to 100 parts by weight of the base polymer (for example, an acrylic polymer), the pigment compound is preferably 0.1 part by weight to 20 parts by weight, more preferably 0.1 part by weight to 10 parts by weight, and further preferably 0.5 part by weight to 5 parts by weight.

[0156] The maximum absorption wavelength in the above pigment compound refers to the absorption maximum wavelength showing the maximum absorbance in the case where there are multiple maximum absorptions in the spectral absorption spectrum in the wavelength region of 300 nm to 460 nm. The maximum absorption wavelength of the absorption spectrum of the above pigment compound more preferably exists in the wavelength region of 380 nm to 420 nm. In addition, the pigment compound is not particularly limited as long as it has the above wavelength characteristics, and a material that does not have fluorescence and phosphorescence properties (photoluminescence) and does not hinder the display performance of the OLED element is preferred.

[0157] Examples of the above pigment compound include organic pigment compounds such as azomethine compounds, indole compounds, cinnamic acid compounds, pyrimidine compounds, porphyrin compounds, and cyanine compounds.

[0158] As the above-mentioned organic pigment compounds, commercially available organic pigment compounds can be preferably used. Specifically, as the above-mentioned indole compounds, examples include: BONASORB UA3911 (trade name, maximum absorption wavelength of absorption spectrum: 398 nm, manufactured by Orient Chemical Industries, Ltd.), as the cinnamic acid compounds, examples include: SOM-5-0106 (trade name, maximum absorption wavelength of absorption spectrum: 416 nm, manufactured by Orient Chemical Industries, Ltd.), as the porphyrin compounds, examples include: FDB-001 (trade name, maximum absorption wavelength of absorption spectrum: 420 nm, manufactured by Yamada Chemical Industries, Ltd.), as the cyanine compounds, examples include: merocyanine compounds (trade name: FDB-009, maximum absorption wavelength of absorption spectrum: 394 nm, manufactured by Yamada Chemical Industries, Ltd.), etc. Among them, from the viewpoints of suppressing crosslinking hindrance and optical reliability, cyanine compounds are preferred, and polymethine compounds are particularly preferred.

[0159] As the above-mentioned pigment compounds, for example, a compound represented by the following formula (1A) (hereinafter sometimes referred to as compound (1A)) which is a cyanine compound can be cited. When there are cis-trans isomers in the compound (1A), the compound (1A) includes any of its cis-trans isomers. In addition, when there are one or more asymmetric carbon atoms in the compound (1A), the compound (1A) includes any one of a compound in which each asymmetric carbon atom is in the R configuration, a compound in the S configuration, and a compound of any combination thereof. It also includes their racemic compounds, racemic mixtures, single enantiomers, and diastereomeric mixtures.

[0160]

[0161] In formula (1A), m represents an integer of 1 to 6. When m is 1, Q 1 represents a hydrogen atom, and when m is 2 to 6, Q 1 represents a divalent to hexavalent linking group. D 1 represents a group obtained by removing one hydrogen atom from the compound represented by the following formula (2A) (hereinafter sometimes referred to as compound (2A)).

[0162]

[0163] In formula (2A), R 1 represents a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent. R 2 represents a hydrogen atom, a cyano group, a nitro group, a trifluoromethyl group, a heterocyclic group-containing group, -C(O)-R 7 or -SO2-R 8 . R 7represents a hydroxyl group or -OR 71 , R 8 represents a halogen atom, a hydroxyl group, -OR 81 , -NR 82 R 83 or -R 84 . R 71 and R 81 ~R 84 are the same or different and represent a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent. R 3 represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group which may have a substituent, or an aryl group which may have a substituent. R 402 and R 403 are the same or different and represent a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent, -NR 406 R 407 , -OR 408 , a cyano group, -C(O)R 409 , -O-C(O)R 410 or -C(O)OR 411 , R 404 ~R 411 are the same or different and represent a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent. R 404 , R 405 , R 404 and R 405 The nitrogen atom to which they are bonded may form a 4- to 8-membered nitrogen-containing heterocycle (a heterocycle containing a nitrogen atom as a ring-constituting atom) which may have a substituent.

[0164] There are no particular limitations on the preferred mode and production method of the compound (1A). For example, it can be produced by the method described in Japanese Patent Laid-Open No. 2018-200463.

[0165] A crosslinking agent can be used in the formation of the adhesive layer. For example, the acrylic polymer in the acrylic adhesive layer can be crosslinked to control the gel fraction. It should be noted that the crosslinking agent can be used alone or in combination of two or more.

[0166] There are no particular limitations on the above-mentioned crosslinking agent. For example, isocyanate crosslinking agents, epoxy crosslinking agents, melamine crosslinking agents, peroxide crosslinking agents, urea crosslinking agents can be cited. Among them, isocyanate crosslinking agents and epoxy crosslinking agents are preferred.

[0167] When a crosslinking agent is used in the formation of the adhesive layer, the amount of the crosslinking agent used is not particularly limited. From the viewpoint of obtaining sufficient adhesive reliability, it is preferably 0.001 parts by weight or more, more preferably 0.01 parts by weight or more, based on 100 parts by weight of the base polymer. In addition, from the viewpoints of obtaining appropriate flexibility in the adhesive layer and improving the adhesive strength, the upper limit of the above-mentioned usage amount is preferably 10 parts by weight or less, more preferably 5 parts by weight or less, based on 100 parts by weight of the base polymer.

[0168] From the viewpoints of improving the adhesive reliability under humid conditions, particularly improving the adhesive reliability to glass, the adhesive layer (especially an acrylic adhesive layer) may contain a silane coupling agent. It should be noted that the silane coupling agent can be used alone or in combination of two or more. When the above-mentioned adhesive layer contains a silane coupling agent, the adhesiveness under humid conditions, particularly the adhesiveness to glass, can be improved.

[0169] The above-mentioned silane coupling agent is not particularly limited. For example, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-phenyl-aminopropyltrimethoxysilane, etc. can be cited. In addition, as the silane coupling agent, commercially available products such as the trade name "KBM-403" (manufactured by Shin-Etsu Chemical Co., Ltd.) can also be cited. Among them, γ-glycidoxypropyltrimethoxysilane is preferably used as the above-mentioned silane coupling agent.

[0170] When the adhesive layer contains a silane coupling agent, the content of the silane coupling agent in the adhesive layer (especially an acrylic adhesive layer) is not particularly limited. Based on 100 parts by weight of the base polymer, it is preferably 0.01 parts by weight or more, more preferably 0.02 parts by weight or more. In addition, based on 100 parts by weight of the base polymer, the upper limit of the content of the silane coupling agent is preferably 10 parts by weight or less, more preferably 1 part by weight or less.

[0171] The adhesive layer may further contain additives such as a light stabilizer, a crosslinking accelerator, a tackifying resin (rosin derivative, polyterpene resin, petroleum resin, oil-soluble phenolic, etc.), an anti-deterioration agent, a filler, a coloring agent (pigment, dye, etc.), an antioxidant, a chain transfer agent, a plasticizer, a softening agent, a surfactant, an antistatic agent, etc., as needed within the range that does not impair the effects of the present invention. In addition, such additives can be used alone or in combination of two or more.

[0172] The method for producing the adhesive layer (especially an acrylic adhesive layer) is not particularly limited. For example, it may include: coating (applying) the above-mentioned adhesive composition on a substrate (including the resin layer and glass layer described later) or a release liner, and drying and curing the obtained adhesive composition layer; coating (applying) the above-mentioned adhesive composition on a substrate (including the resin layer and glass layer described later) or a release liner, and irradiating the obtained adhesive composition layer with active energy rays to cure it. Additionally, heat drying may be further performed as needed.

[0173] Examples of the above-mentioned active energy rays include ionizing rays such as α-rays, β-rays, γ-rays, neutron rays, and electron rays, and ultraviolet rays, with ultraviolet rays being particularly preferred. Additionally, the irradiation energy, irradiation time, irradiation method, etc. of the active energy rays are not particularly limited.

[0174] The above-mentioned adhesive composition can be produced by known or conventional methods. For example, a solvent-based acrylic adhesive composition can be produced by mixing additives (such as ultraviolet absorbers, etc.) as needed in a solution containing the acrylic polymer. For example, an active energy ray-curable acrylic adhesive composition can be produced by mixing additives (such as ultraviolet absorbers, etc.) as needed in a mixture of the aforementioned acrylic monomers or a partial polymer thereof. It should be noted that the coating (application) of the above-mentioned adhesive composition can be carried out using known coating methods. For example, coating machines such as gravure roll coaters, reverse roll coaters, roll kiss coaters, dip roll coaters, bar coaters, knife coaters, spray coaters, comma coaters, and direct coaters can be used.

[0175] Especially when forming an adhesive layer using an active energy ray-curable adhesive composition, the active energy ray-curable adhesive composition preferably contains a photoinitiator. It should be noted that when the active energy ray-curable adhesive composition contains an ultraviolet absorber, as the photoinitiator, it is preferably at least a photoinitiator having light absorption characteristics in a wide wavelength range. For example, it is preferably at least a photoinitiator having light absorption characteristics not only for ultraviolet light but also for visible light. This is because there is a concern that the curing caused by active energy rays may be hindered by the action of the ultraviolet absorber, and when a photoinitiator having light absorption characteristics in a wide wavelength range is included, high photocurability can be easily obtained in the adhesive composition.

[0176] (Adhesive layer)

[0177] The adhesive layer refers to a layer that can bond substances by being sandwiched between adherends, and it refers to a layer that does not have practical adhesive force when the adherends pasted using the adhesive layer are peeled off.

[0178] As the adhesive for forming the adhesive layer constituting the optical element, various adhesives can be applied. For example, the following can be cited: isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latexes, aqueous polyesters, etc. These adhesives are usually used as adhesives containing an aqueous solution (aqueous adhesives) and contain 0.5% to 60% by weight of solid components.

[0179] The above-mentioned adhesives may contain crosslinking agents and additives. As the above-mentioned additives, for example, the following can be cited: coupling agents such as silane coupling agents and titanium coupling agents, adhesion promoters such as ethylene oxide, ultraviolet absorbers, anti-degradants, dyes, processing aids, ion trappers, antioxidants, tackifiers, fillers, plasticizers, leveling agents, foam inhibitors, antistatic agents, heat stabilizers, hydrolysis stabilizers, etc.

[0180] (Resin layer)

[0181] The resin layer constituting the optical element is not particularly limited. For example, a plastic film can be cited. As the material for the above-mentioned plastic film, etc., for example, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) with excellent dimensional stability and difficult to shrink, cyclic olefin polymers (COP), polycarbonate (PC), polyether ether ketone (PEEK), and transparent polyimide (CPI) are preferred. It should be noted that these plastic materials can be used alone or in combination of two or more. The release liner peeled off when using the optical element (during pasting) is not included in the "resin layer".

[0182] The resin layer is preferably transparent. The total light transmittance in the visible light wavelength region of the resin layer (according to JIS K7361-1) is not particularly limited, preferably 85% or more, more preferably 88% or more.

[0183] The refractive index difference between the adhesive layer and the resin layer in the present invention (the absolute value of "refractive index of the adhesive layer" - "refractive index of the resin layer") is not particularly limited. From the viewpoints of improving the interfacial antireflectivity and the light collection rate of the light emitted from the OLED element, it is preferably 2 or less, preferably 1 or less, more preferably 0.5 or less, and particularly preferably 0.3 or less. In the case where the resin layer includes a multilayer structure of two or more continuous layers, the above refractive index difference is measured by regarding the two or more layers as one resin layer.

[0184] The thickness of the resin layer is not particularly limited, and is preferably 10 μm to 80 μm, for example. It should be noted that the resin layer can have any form of single layer or multiple layers. In addition, the surface of the resin layer can be appropriately subjected to known and conventional surface treatments such as physical treatments such as corona discharge treatment and plasma treatment, and chemical treatments such as undercoat treatment. In the case where the resin layer includes a multilayer structure of two or more continuous layers, the above thickness is measured by treating the two or more layers as one resin layer.

[0185] The resin layer preferably contains an ultraviolet absorber (UVA) and a pigment compound whose maximum absorption wavelength of the absorption spectrum is in the wavelength range of 380 nm to 430 nm. When the resin layer contains an ultraviolet absorber and the above pigment compound, it is possible to suppress the deterioration of the OLED element caused by ultraviolet rays contained in external light, and an OLED display device with excellent weather resistance can be obtained even without using a polarizing plate. In addition, it is possible to suppress the deterioration of the high refractive index component of the adhesive layer caused by ultraviolet rays, and a high light transmittance can be maintained. In particular, by including an ultraviolet absorber and the above pigment compound in the resin layer, the content of the ultraviolet absorber and the above pigment compound in the adhesive layer can be reduced, and the precipitation and exudation of the ultraviolet absorber and the above pigment compound in the adhesive layer can be suppressed, which is preferable.

[0186] As the ultraviolet absorber (UVA) and the above pigment compound contained in the resin layer, the same substances as the ultraviolet absorber and the above pigment compound contained in the above adhesive layer can be used. It should be noted that the ultraviolet absorber and the above pigment compound can be used alone or in combination of two or more.

[0187] When the resin layer contains an ultraviolet absorber and the above pigment compound, the content of each of the above ultraviolet absorber and the above pigment compound in the resin layer is not particularly limited. From the viewpoint of suppressing the deterioration of the OLED element caused by ultraviolet rays contained in external light and obtaining an OLED display device with excellent weather resistance even without using a polarizing plate, the content of each of the above ultraviolet absorber and the above pigment compound in the resin layer is preferably 0.01% by weight or more, more preferably 0.05% by weight or more, and further preferably 0.1% by weight or more, based on 100% by weight of the resin layer. In addition, from the viewpoint of suppressing the occurrence of yellowing of the adhesive accompanied by the addition of the ultraviolet absorber and obtaining excellent optical properties, high transparency, and excellent appearance properties, the upper limit of the content of the above ultraviolet absorber and the above pigment compound is preferably 10% by weight or less, more preferably 9% by weight or less, and further preferably 8% by weight or less, based on 100% by weight of the resin layer.

[0188] When both the resin layer and the adhesive layer contain an ultraviolet absorber and the above pigment compound, it is only necessary to adjust the total amount to the above range.

[0189] (Glass layer)

[0190] The glass layer constituting the optical element is not particularly limited, and an appropriate glass layer can be adopted according to the purpose. According to the classification based on the composition, the glass layer can be exemplified by soda-lime glass, boric acid glass, aluminosilicate glass, quartz glass, etc. In addition, according to the classification based on the alkali component, alkali-free glass and low-alkali glass can be exemplified. The content of the alkali metal component (for example, Na2O, K2O, Li2O) of the above glass is preferably 15% by weight or less, and more preferably 10% by weight or less.

[0191] (Hard coat)

[0192] The hard coat constituting the optical element can be formed of any appropriate resin as long as it has sufficient surface hardness, excellent mechanical strength, and excellent light transmittance. Specific examples of the resin can be exemplified by thermosetting resins, thermoplastic resins, ultraviolet curable resins, etc.

[0193] As the ultraviolet curable resin, polyester-based, acrylic-based, urethane-based, amide-based, silicone-based, and epoxy-based ultraviolet curable resins can be exemplified. The ultraviolet curable resin contains ultraviolet curable monomers, oligomers, and polymers. As a preferred ultraviolet curable resin, a resin composition containing an acrylic monomer component or oligomer component having preferably 2 or more, more preferably 3 to 6 ultraviolet polymerizable functional groups can be exemplified. The ultraviolet curable resin can be blended with a photoinitiator.

[0194] (Anti-reflection layer)

[0195] As the anti-reflection layer constituting the optical element, any appropriate configuration can be adopted. For example, (i) a single layer of a low refractive index layer with an optical film thickness of 120 nm to 140 nm and a refractive index of 1.35 to 1.55, (ii) a laminate having a middle refractive index layer, a high refractive index layer, and a low refractive index layer in sequence, and (iii) an alternating multilayer laminate of a high refractive index layer and a low refractive index layer can be exemplified.

[0196] Examples of materials capable of forming a low refractive index layer include silicon oxide (SiO2) and magnesium fluoride (MgF2). The refractive index of the low refractive index layer is typically about 1.35 to about 1.55. Examples of materials capable of forming a high refractive index layer include titanium oxide (TiO2), niobium oxide (Nb2O3 or Nb2O5), indium tin oxide (ITO), etc. The refractive index of the high refractive index layer is typically about 1.60 to about 2.20. Examples of materials capable of forming a medium refractive index layer include titanium oxide (TiO2), and a mixture of a material capable of forming a low refractive index layer and a material capable of forming a high refractive index layer (e.g., a mixture of titanium oxide and silicon oxide). The refractive index of the medium refractive index layer is typically about 1.50 to about 1.85. The thicknesses of the low refractive index layer, the medium refractive index layer, and the high refractive index layer can be set in a manner that achieves an appropriate optical film thickness corresponding to the layer structure of the antireflection layer, the desired antireflection performance, etc.

[0197] (Anti-glare layer)

[0198] As the anti-glare layer constituting the optical element, a known anti-glare layer can be used without limitation, and it is usually formed as a layer in which inorganic or organic particles as anti-glare agents are dispersed in a resin.

[0199] The anti-glare layer is not particularly limited. For example, it is formed using an anti-glare layer forming material containing a resin, particles, and a thixotropy imparting agent. By aggregating the above-mentioned particles and the above-mentioned thixotropy imparting agent, convex portions are formed on the surface of the anti-glare layer. With this configuration, the anti-glare layer has excellent display characteristics that balance anti-glare properties and prevention of white blurring, and although the anti-glare layer is formed by aggregating particles, it is possible to prevent the generation of protrusions on the surface of the anti-glare layer that would be appearance defects, thereby improving the product yield.

[0200] (Intermediate layer)

[0201] The intermediate layer constituting the optical element is formed between the resin layer and the hard coat layer, the antireflection layer, or the anti-glare layer. By forming this intermediate layer, the adhesion between the resin layer and the above-mentioned hard coat layer, antireflection layer, or anti-glare layer is improved.

[0202] The resin contained in the intermediate layer is not particularly limited. For example, it can be a resin obtained by simply mixing (compatibilizing) the resin contained in the resin layer with the resin contained in the hard coat layer, the antireflection layer, or the anti-glare layer. Additionally, the resin contained in the intermediate layer can be, for example, a resin in which at least one of the resin contained in the resin layer and the resin contained in the hard coat layer, the antireflection layer, or the anti-glare layer has undergone a chemical change by heating, light irradiation, etc.

[0203] (Impact absorption layer)

[0204] The shock-absorbing layer constituting the optical element may be constituted by any suitable resin layer capable of achieving the desired shock absorption rate. The resin layer may be constituted by a resin film or an adhesive. The shock-absorbing layer typically includes an epoxy resin, a urethane resin, or an acrylic resin. These resins may be used alone or in combination.

[0205] (Antistatic layer)

[0206] The antistatic layer constituting the optical element is not particularly limited. For example, it is an antistatic layer formed by coating a conductive coating liquid containing a conductive polymer.

[0207] (Manufacturing method of the optical laminate)

[0208] The manufacturing method of the optical laminate is not particularly limited. It can be manufactured by sequentially laminating an adhesive layer, an adhesive layer, a resin layer, a glass layer, a hard coat layer, an antireflection layer, an antiglare layer, an intermediate layer (compatibilizing layer), a shock-absorbing layer, etc. on the visual recognition side of the OLED display panel. Additionally, it can be manufactured by prefabricating the laminate constituting the optical laminate and laminating it on the visual recognition side of the OLED display panel. In the case of prefabricating the laminate constituting the optical laminate, it can be the entire laminate constituting the optical laminate, or the laminate of a part of the optical laminate can be separately laminated on the visual recognition side of the OLED display panel. The layer or its laminate constituting the optical element can be protected with a release liner or a surface protective film before use.

[0209] (Release liner)

[0210] A release liner may be provided on the surface (adhesive surface) of the adhesive layer before use. The release liner can be used as a protective material for the adhesive layer and is peeled off when pasted onto the adherend. It should be noted that the release liner is not an element constituting the optical element and may not be provided.

[0211] (Surface protective film)

[0212] The outermost surface of the optical laminate (the outermost surface on the visual recognition side) can be protected by a surface protective film. The surface protective film can also be pasted by the consumer. It should be noted that the surface protective film is not an element constituting the optical element and may not be provided. As the above surface protective film, a known or conventional surface protective film can be used, and there is no particular limitation. For example, a surface protective film having an adhesive layer on the surface of a plastic film can be used.

[0213] (The OLED display device of the present invention)

[0214] Hereinafter, an embodiment of an OLED display device in which an optical laminate is laminated on the visual recognition side of an OLED display panel will be described with reference to the accompanying drawings. However, the present invention is not limited to this embodiment. Figure 2 It is a schematic cross-sectional view showing an embodiment of the basic configuration of an OLED display device on which an optical laminate is laminated.

[0215] As Figure 2 shown, in the OLED display device 200, layers constituting the optical laminate 20 are laminated on the visual recognition side ( Figure 2 the upper side) of the OLED display panel 100. The OLED display panel 100 is not particularly limited. For example, it may have the same structure as the OLED display panel 100 described in Figure 1 .

[0216] In Figure 2 the OLED display device 200, 21 to 29 are layers constituting the optical laminate 20. 21 represents an adhesive layer or an adhesive agent layer, 22 represents a resin layer, a glass layer, or an impact absorption layer, 23 represents a hard coat layer or an antiglare layer, 24 represents an adhesive layer or an adhesive agent layer, 25 represents a resin layer, a glass layer, or an impact absorption layer, 26 represents an adhesive layer or an adhesive agent layer, 27 represents a resin layer, a glass layer, or an impact absorption layer, 28 represents a hard coat layer or an antiglare layer, 29 represents an antireflection layer, and any one of 21, 24, and 26 is an adhesive layer. Figure 2 The laminated structure of the optical laminate 20 shown is not limited to this embodiment. Other layers constituting optical elements can be inserted between any layers of the laminated structure of the optical laminate 20 shown, or any layer of the laminated structure of the optical laminate 20 shown may not exist. Figure 2 shown, and any layer of the laminated structure of the optical laminate 20 shown may not exist. Figure 2 shown.

[0217] Figure 3 In (a) to (c), 300 is an adhesive film with a substrate, 301 is an adhesive film, 302 is an OLED display device, 31 is an adhesive layer, 32 is a substrate (resin layer), 33 is a release liner, and 100 is an OLED display panel.

[0218] In Figure 3 (a), the adhesive film 300 with a substrate has a form in which an adhesive layer 31 and a substrate 32 are laminated in this order on the upper side of the release liner 33. The substrate 32 is not an essential component (refer to Figure 3(b)), but from the viewpoint of improving impact resistance, the base material 32 is preferably present. The release liner 33 is temporarily adhered to the surface of the adhesive layer 31. The release liner 33 is not particularly limited. For example, a release liner formed by providing a release layer formed of a release treatment agent on one side of a sheet-like base material and having the one side as a release surface can be preferably used. Before bonding to the OLED display panel 100 as an adherend, the release liner 33 is peeled off from the surface of the adhesive layer 31, and the exposed surface of the adhesive layer 31 is bonded to the surface of the OLED display panel 100, whereby the adhesive film is temporarily bonded to the OLED display panel 100. The thickness of the release liner 33 is not particularly limited. For example, it is 3 μm to 200 μm, preferably 10 μm to 100 μm.

[0219] The form in which the adhesive film obtained by the above operation is temporarily bonded to the OLED display panel 100 is Figure 3 (c). In Figure 3 (c), the adhesive layer 31 of the adhesive film is in contact with the visually recognizable side (upper side) of the OLED display panel 100.

[0220] In the case where the adhesive film 300 has the base material 32, an adhesive film omitting the release liner 33 can also be used. By winding the adhesive film 300, the adhesive surface of the adhesive layer 31 that does not face the base material 32 can be in a state of being protected by contacting the surface of the base material 32 where the adhesive layer 31 does not exist (reel form). In the case of an adhesive film having a reel form, before bonding to the OLED display panel 100, the surface of the adhesive layer 31 is exposed, and the exposed surface of the adhesive layer 31 is bonded to the surface of the OLED display panel 100, whereby the adhesive film is temporarily bonded to the OLED display panel 100.

[0221] For the adhesive film temporarily bonded to the adherend, by performing an adhesive force increasing treatment on the adhesive layer 31, the adhesive force of the adhesive layer 31 is increased, and the adherend and the base material 32 are fixed by the adhesive layer 31.

[0222] In this specification, "fixation" means a state in which two laminated layers are firmly adhered and it is impossible or difficult to peel them at the interface between the two. "Temporary adhesion" means a state in which the adhesive force between two laminated layers is small and it is easy to peel them at the interface between the two.

[0223] Examples

[0224] Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

[0225] [Example 1: Production of Adhesive Film 1]

[0226] · Preparation of (meth)acrylic polymer

[0227] Into a four-necked flask equipped with a stirrer, a thermometer, a nitrogen inlet tube, and a condenser, a monomer mixture containing 94.9 parts by weight of butyl acrylate (BA), 5 parts by weight of acrylic acid (AA), and 0.1 part by weight of 2-hydroxyethyl acrylate (HEA) was charged. In addition, 0.1 part by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator was added together with ethyl acetate relative to 100 parts by weight of the monomer mixture (solid content). While slowly stirring, nitrogen was introduced, and thus nitrogen replacement was carried out. Then, the liquid temperature in the flask was maintained at around 55 °C and a polymerization reaction was carried out for 7 hours. Then, ethyl acetate was added to the obtained reaction solution to adjust the solid content concentration to 30%, thereby preparing a solution of a (meth)acrylic polymer having a weight average molecular weight of 2 million.

[0228] · Preparation of acrylic adhesive composition 1

[0229] Relative to 100 parts by weight of the solid content of the obtained (meth)acrylic polymer solution, 2.3 parts by weight of an ultraviolet absorber (2,4-bis -[{4-(4-ethylhexyloxy)-4-hydroxy}-phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine, trade name: Tinosorb S, manufactured by BASF), 3.5 parts by weight of a pigment compound (polymethine compound of the following formula (3)), 0.1 part by weight of an isocyanate crosslinking agent (trade name: Takenate D110N, trimethylolpropane benzylidene diisocyanate, manufactured by Mitsui Chemicals, Inc.), 0.3 part by weight of benzoyl peroxide as a peroxide crosslinking agent (trade name: NYPERBMT, manufactured by NOF Corporation), and 0.08 part by weight of a silane coupling agent (trade name: KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.) were blended, thereby preparing acrylic adhesive composition 1.

[0230]

[0231] · Production of adhesive film 1

[0232] Acrylic adhesive composition 1 was uniformly coated on the surface of a polyethylene terephthalate film (PET film, transparent substrate, release liner) having a thickness of 38 μm treated with a polysiloxane-based release agent using a fountain coater and dried in an air-circulating constant-temperature oven at 155 °C for 2 minutes, thereby forming an adhesive layer having a thickness of 20 μm. Then, the obtained adhesive layer was peeled off from the PET film, thereby producing adhesive film 1. Adhesive film 1 corresponds to a "substrate-free adhesive film".

[0233] [Example 2: Production of adhesive film 2]

[0234] · Preparation of acrylic adhesive composition 2

[0235] With respect to 100 parts by weight of the solid content of the (meth)acrylic polymer solution, the compounding amount of the ultraviolet absorber was set to 1.3 parts by weight, and the compounding amount of the pigment compound was set to 4.3 parts by weight. Except for this, an acrylic adhesive composition 2 was prepared in the same manner as in Example 1.

[0236] · Production of Adhesive Film 2

[0237] The acrylic adhesive composition 2 was uniformly coated on the surface of a polyethylene terephthalate film (PET film, transparent substrate, release liner) with a thickness of 38 μm treated with a polysiloxane-based release agent using a fountain coater, and dried in an air-circulation constant-temperature oven at 155°C for 2 minutes, thereby forming an adhesive layer with a thickness of 20 μm. Then, it was pasted onto a transparent plastic film substrate (acrylic film, manufactured by Toyo Kohan Co., Ltd., trade name "HX40UF", thickness: 40 μm), and the PET film was peeled off, thereby producing an adhesive film 2. The adhesive film 2 corresponds to a "substrate-attached adhesive film".

[0238] [Example 3: Production of Adhesive Film 3]

[0239] · Preparation of Acrylic Adhesive Composition 3

[0240] With respect to 100 parts by weight of the solid content of the (meth)acrylic polymer solution, the compounding amount of the ultraviolet absorber was set to 0.8 parts by weight, and the compounding amount of the pigment compound was set to 2.3 parts by weight. Except for this, an acrylic adhesive composition 3 was prepared in the same manner as in Example 1.

[0241] · Production of Adhesive Film 3

[0242] The acrylic adhesive composition 3 was uniformly coated on the surface of a polyethylene terephthalate film (PET film, transparent substrate, release liner) with a thickness of 38 μm treated with a polysiloxane-based release agent using a fountain coater, and dried in an air-circulation constant-temperature oven at 155°C for 2 minutes, thereby forming an adhesive layer with a thickness of 40 μm. Then, it was pasted onto a substrate (trade name "RV20", thickness 20 μm, manufactured by Toyo Kohan Co., Ltd.), and the PET film was peeled off, thereby producing an adhesive film 3. The adhesive film 3 corresponds to a "substrate-attached adhesive film".

[0243] [Comparative Example 1: Production of Adhesive Film 4]

[0244] As the acrylic adhesive composition 1, a composition not containing an ultraviolet absorber was used, and in other respects, the acrylic adhesive composition 4 was prepared in the same manner as in Example 1. In addition, except for using the acrylic adhesive composition 4, the operation was the same as in Example 1 to produce the adhesive film 4. The adhesive film 4 corresponds to a "substrate-free adhesive film".

[0245] [Comparative Example 2: Production of Adhesive Film 5]

[0246] The acrylic adhesive composition 4 was uniformly coated on the surface of a polyethylene terephthalate film (PET film, transparent substrate, release liner) with a thickness of 38 μm treated with a polysiloxane-based release agent using a fountain coater, and dried in an air-circulation constant-temperature oven at 155°C for 2 minutes to form an adhesive layer with a thickness of 20 μm. Then, it was pasted onto a transparent plastic film substrate (acrylic film, manufactured by Toyo Kohan Co., Ltd., trade name "HX40UF", thickness: 40 μm), and the PET film was peeled off, thereby producing the adhesive film 5. The adhesive film 5 corresponds to a "substrate-containing adhesive film".

[0247] [Comparative Example 3: Production of Adhesive Film 6]

[0248] The acrylic adhesive composition 4 was uniformly coated on the surface of a polyethylene terephthalate film (PET film, transparent substrate, release liner) with a thickness of 38 μm treated with a polysiloxane-based release agent using a fountain coater, and dried in an air-circulation constant-temperature oven at 155°C for 2 minutes to form an adhesive layer with a thickness of 40 μm. Then, it was pasted onto a substrate (trade name "RV20", thickness 20 μm, manufactured by Toyo Kohan Co., Ltd.), and the PET film was peeled off, thereby producing the adhesive film 6. The adhesive film 6 corresponds to a "substrate-containing adhesive film".

[0249] Evaluation

[0250] For the adhesive films 1 to 6 obtained in the examples and comparative examples, the following evaluations were carried out.

[0251] (Measurement of the weight-average molecular weight (Mw) of the (meth)acrylic polymer)

[0252] The weight-average molecular weight (Mw) of the obtained (meth)acrylic polymer was measured by GPC (gel permeation chromatography).

[0253] · Analytical device: HLC-8120 GPC manufactured by Tosoh Corporation

[0254] · Column: G7000 HXL + GMHXL + GMHXL manufactured by Tosoh Corporation

[0255] · Column size: Each 7.8 mmφ × 30 cm, total 90 cm

[0256] · Column temperature: 40 °C

[0257] · Flow rate: 0.8 ml / min

[0258] · Injection volume: 100 μl

[0259] · Eluent: Tetrahydrofuran

[0260] · Detector: Differential refractometer (RI)

[0261] · Standard sample: Polystyrene

[0262] (Evaluation of water vapor transmission rate)

[0263] The water vapor transmission rate of the adhesive films obtained in the examples and comparative examples was investigated. Specifically, in an environment of 40 °C and 92% relative humidity, the water vapor transmission rate (g / m 2 · 24 h) of the adhesive film was measured according to JIS Z0208. The results are shown in Table 1.

[0264] (Measurement of light transmittance)

[0265] The adhesive films obtained in the examples and comparative examples were laminated on a glass plate to obtain test specimens for measurement. The light transmittance spectrum at room temperature (23 °C) was measured using a visible ultraviolet spectrophotometer (Spectrophotometer U4100, manufactured by Hitachi High-Technologies Corporation), and the light transmittance (%) at a wavelength of 380 nm was read. Similarly, the light transmittance (%) at a wavelength of 450 nm was measured. The results are shown in Table 1.

[0266] (Measurement of the change ratio of light transmittance before and after humidification)

[0267] After exposing the adhesive films obtained in the examples and comparative examples to an environment of 85 °C and 85% relative humidity for 240 hours, the change ratio of the light transmittance before and after humidification at a wavelength of 380 nm was calculated according to the following formula.

[0268] Change ratio of light transmittance at a specific wavelength before and after humidification = (Light transmittance at a specific wavelength after humidification) / (Initial light transmittance at a specific wavelength)

[0269] The results are shown in "Change ratio of light transmittance at a wavelength of 380 nm before and after 85 °C 85% (after 240 hours)" in Table 1.

[0270] (Measurement of loss factor (tanδ))

[0271] The adhesive films obtained in the examples and comparative examples were blanked into Φ8 mm size using a jig, and the probes of ARES-G2 (TA instruments) were set. Measurements were carried out at intervals of 5 °C in the range from -50 °C to 200 °C under the conditions of 0.05% strain and 1 Hz frequency. The peak top value of the loss factor (tanδ) was extracted from the obtained data ( Figure 4 ). The results are shown in "Loss factor (tanδ)" in Table 1. It should be noted that although Figure 4 only shows that Examples 1 and Comparative Example 1 have peaks of the loss factor (tanδ) in the region below 0 °C, Examples 2 and 3 also have peaks of the loss factor (tanδ) in the region below 0 °C.

[0272] (Evaluation of impact force)

[0273] The impact force (N) of the adhesive films obtained in the examples and comparative examples was evaluated by the falling ball test described below. The results are shown in Table 1.

[0274] · Preparation of evaluation samples

[0275] For the adhesive films described in the examples and comparative examples, (1) a pressure-sensitive paper (manufactured by Fujifilm Corporation, PRESCALE ultra-low pressure pressure measurement film) was installed on one surface of the adhesive layer or (2) on the surface of the adhesive layer opposite to the surface to which the substrate was adhered, thereby obtaining samples in which the substrate, the adhesive layer, and the pressure-sensitive paper were laminated in sequence. The obtained samples were subjected to autoclave treatment (50 °C, 0.5 MPa, 15 minutes) to obtain evaluation samples. It should be noted that for the above (1), it corresponds to Adhesive Films 1 and 4 for Example 1 and Comparative Example 1, and for the above (2), it corresponds to their adhesive films for other examples and comparative examples.

[0276] · Test method

[0277] 1: The evaluation samples of Examples 1 to 3 and Comparative Examples 1 to 3 were placed on the stage of the ball drop impact testing machine ( Figure 5 X). It should be noted that Figure 5 X1 of

[0278] is the substrate, X2 is the adhesive layer, and X3 is the pressure-sensitive paper. In the evaluation samples of Example 1 and Comparative Example 1, X1 does not exist. Figure 5 2: A 10 g iron ball ( Figure 5 X4 of

[0279] ) was placed at a height of 30 cm (

[0280]

Claims

1. An adhesive film for an OLED display device, wherein the adhesive film is used for an OLED display device in which only an optical element having a polarization degree of 95% or less is laminated on a visual recognition side of an OLED element, characterized in that: The adhesive film for an OLED display device has at least one layer containing an ultraviolet absorber as a layer constituting the optical element, The adhesive film for an OLED display device comprises an adhesive layer, wherein the adhesive layer has a peak of a loss factor (tan δ) in a region below 0° C., and the peak top value of the peak is 1.5 or more. The adhesive film for an OLED display device has a light transmittance of 20% or less at a wavelength of 380 nm.

2. The adhesive film for an OLED display device according to claim 1, wherein: The adhesive layer contains an ultraviolet absorber.

3. The adhesive film for an OLED display device according to claim 1 or 2, wherein: The adhesive film for an OLED display device further includes a resin layer.

4. An OLED display device, in which only an optical element having a polarization degree of 95% or less is stacked on the visual recognition side of the OLED element, wherein: The OLED display device comprises the adhesive film according to claim 1 or 2.

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