Self-adhesive film for OLED display unit

Abstract

To provide a self-adhesive film capable of imparting high weather resistance to an OLED display unit using no polarizer.SOLUTION: A self-adhesive film for an OLED display unit is to be used for an OLED display unit with only an optical element in a polarization degree of 95% or less laminated on a visible side of an OLED element. The self-adhesive film includes at least one layer containing an ultraviolet absorber as a layer composing the optical element. The self-adhesive film includes an adhesive layer. In the self-adhesive film, light transmittance at a wavelength 380 nm is 20% or less, and variation ratios of light transmittance at wavelengths 380 nm, 450 nm, 550 nm and 650 nm respectively are 0.9 to 1.2 after an exposure for 240 hours in an environment at a temperature 85°C and relative humidity 85%.SELECTED DRAWING: Figure 3

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 for an OLED display device that does not use a polarizing plate.

Background Art

[0002] An OLED (Organic light emitting diode) display device has advantages in display performance such as high visibility, low viewing angle dependence, and fast response speed compared to a liquid crystal display device. In addition, since the OLED display device does not use a backlight, it is advantageous for thinning, and can also be used as a flexible and foldable device that can be curved 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 laminated in this order. Since a transparent conductive material with a high refractive index such as ITO or a metal material with a high reflectivity is used for the electrodes (anode or cathode) of the OLED element, external light is reflected by the electrodes, causing problems such as contrast reduction and reflection due to internal reflection, and the display performance of the OLED display device may deteriorate. In order to suppress the adverse effects caused by external light reflection, a proposal has been made to dispose a polarizing plate and a circular polarizing plate such as a λ / 4 plate on the viewing side of the OLED display device (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 due to ultraviolet rays. Furthermore, due to the mechanical properties of the circular polarizing plate itself, it also has a function of absorbing external impacts and preventing damage to the OLED display device. However, when using a circular polarizing plate, the light utilization efficiency (i.e., light collection rate) is poor due to absorption by the polarizing plate, and the brightness decreases. Increasing the light emission intensity of the OLED element to obtain the desired brightness leads to an increase in power consumption and a shortening of the lifespan of the OLED element. In addition, when the polarizing plate includes an adhesive layer for pasting, it has a thickness of about 0.15 mm, which is disadvantageous for the thinning of the OLED display device. Furthermore, since the circular polarizing plate is expensive, there is also a problem that the manufacturing cost increases.

[0004] As an alternative to a circular polarizing plate, a method has been proposed in which a color filter is disposed on the viewing side of an OLED element and alignment is performed so that the color filter having the same color as the light emission color of the OLED layer faces each other, thereby improving the light emission luminance 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, it is said that the spectrum of the light extracted to the outside becomes steep and high-intensity, so that the luminance and color purity can be improved (for example, Patent Document 3). In an OLED display device, on the viewing side of the OLED element, layers of various optical elements such as an adhesive layer, a base material such as plastic or thin glass, and a hard coat layer are laminated in order to impart functions such as surface protection and flexibility.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in an OLED display device that does not use such a polarizing plate, there has been a problem that the weather resistance of the OLED element is low. The reason is that, compared with the case of using a polarizing plate, the ultraviolet absorption function of the color filter is not sufficient, and thus the OLED element is likely to deteriorate over time due to ultraviolet rays contained in external light.

[0007] Accordingly, an object of the present invention is to provide an adhesive film capable of imparting high weather resistance to an OLED display device that does not use a polarizing plate.

Means for Solving the Problems

[0008] As a result of intensive studies to achieve the above object, the present inventors have found that an OLED display device using an adhesive film for an OLED display device having a specific configuration exhibits sufficient weather resistance even when the OLED display device does not use a polarizing plate, and thus completed the present invention.

[0009] That is, in the present invention, there is provided an adhesive film used for an OLED display device in which only optical elements having a polarization degree of 95% or less are laminated on the viewing side of an OLED element, as a layer constituting the optical element, having at least one layer containing an ultraviolet absorber, having an adhesive layer, the light transmittance at a wavelength of 380 nm is 20% or less, and there is provided an adhesive film for an OLED display device, characterized in that the variation ratio of the light transmittance at 380 nm, 450 nm, 550 nm, and 650 nm after exposure to an environment of a temperature of 85° C. and a relative humidity of 85% for 240 hours is 0.9 to 1.2.

[0010] It is preferable that the adhesive layer contains an ultraviolet absorber.

[0011] It is preferable that the adhesive film further has a resin layer.

[0012] The present invention also provides an OLED display device in which only optical elements having a polarization degree of 95% or less are laminated on the viewing side of an OLED element, including the above adhesive film.

Effects of the Invention

[0013] The adhesive film of the present invention can impart high weather resistance to an OLED display device that does not use a polarizing plate.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0015] The present invention provides an adhesive film for an OLED display device. The adhesive film for an OLED display device of the present invention may be referred to as "the adhesive film of the present invention". Further, the present invention provides an OLED display device including an optical laminate including the 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.

[0016] In the OLED display device of the present invention, only an optical element with a polarization degree of 95% or less is laminated on the viewing side of the OLED element of the OLED display panel. "Only an optical element with a polarization degree of 95% or less is laminated on the viewing side of the OLED element" means that the optical element on the viewing side of the OLED element does not include an optical element with a polarization degree exceeding 95%. The "optical element with a polarization degree exceeding 95%" is not particularly limited, but includes polarizing plates such as a linear polarizing plate, a quarter-wave plate, a half-wave plate, a circular polarizing plate, and a reflective polarizing plate. That is, the OLED display device of the present invention is an OLED display device that does not include a polarizing plate on the viewing side of the OLED element. The polarization degree is 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 visual sensitivity. Polarization degree (%) = {(Tp - Tc) / (Tp + Tc)} 1 / 2 × 100

[0017] Since the OLED display device of the present invention does not include a polarizing plate on the viewing side of the OLED element, the absorption of light emitted from the OLED element by the polarizing plate is suppressed, the light collection rate is improved, power consumption can be saved, and the long life of the OLED element can be achieved. In addition, by not using a polarizing plate, thinning is possible and the manufacturing cost can be reduced.

[0018] The adhesive film of the present invention has an adhesive layer and has at least one layer containing an ultraviolet absorber as a layer constituting an optical element in the OLED display device. The adhesive film of the present invention has a light transmittance of 20% or less at a wavelength of 380 nm, and the variation ratio of the light transmittance at 380 nm, 450 nm, 550 nm, and 650 nm after being exposed to an environment of a temperature of 85 °C and a relative humidity of 85% for 240 hours is 0.9 to 1.2. The fact that the adhesive film of the present invention has the above characteristics is suitable in terms of improving the weather resistance in the OLED display device.

[0019] The pressure-sensitive adhesive film of the present invention includes at least a pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer may be a layer containing an ultraviolet absorber. The pressure-sensitive adhesive film of the present invention may also have a resin layer in addition to the pressure-sensitive adhesive layer, and the resin layer may be a layer containing an ultraviolet absorber. When the pressure-sensitive adhesive film of the present invention has a resin layer, it is preferable from the viewpoint of improving impact resistance. Further, the pressure-sensitive adhesive film of the present invention may have, as a component of the pressure-sensitive adhesive film, an optical element other than the above-described pressure-sensitive adhesive layer and resin layer laminated on the OLED display device of the present invention. In the pressure-sensitive adhesive film of the present invention, at least one layer of the pressure-sensitive adhesive layers may be a pressure-sensitive adhesive layer having a high refractive index, and all of them may be pressure-sensitive adhesive layers having a high refractive index.

[0020] The moisture permeability of the pressure-sensitive adhesive film of the present invention is not particularly limited. For example, 5000 g / m 2 ·24 h or less is preferable, more preferably 3500 g / m 2 ·24 h or less, more preferably 2000 g / m 2 ·24 h or less, more preferably 1000 g / m 2 ·24 h or less, more preferably 500 g / m 2 ·24 h or less, more preferably 200 g / m 2 ·24 h or less, still more preferably 100 g / m 2 ·24 h or less, particularly preferably 80 g / m 2 ·24 h or less. The lower limit value of the moisture permeability is not particularly limited, but from the viewpoint of suppressing swelling due to humidification, it is 10 g / m 2 ·24 h. When the pressure-sensitive adhesive film of the present invention is within the above range, there is a tendency to suppress deterioration of the panel due to moisture. The moisture permeability of the pressure-sensitive adhesive film of the present invention can be measured in accordance with JIS Z0208 under the environment of a temperature of 40°C and a relative humidity of 92%, and can be adjusted according to the type, thickness, etc. of the resin constituting the pressure-sensitive adhesive film of the present invention.

[0021] The light transmittance of the pressure-sensitive 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, still more preferably 2% or less, and particularly preferably 1% or less. The lower limit of the light transmittance at a wavelength of 380 nm is 0%. The method for measuring the light transmittance at a wavelength of 380 nm is not particularly limited, but for example, it can be measured by using a spectrophotometer U4100 (manufactured by Hitachi High-Technologies Corporation). The light transmittance at wavelengths other than 380 nm can also be measured by the above-mentioned device in the same manner.

[0022] The light transmittance of the pressure-sensitive adhesive film of the present invention at a wavelength of 450 nm is not particularly limited, but for example, it is preferably 20% or less, more preferably 15% or less, more preferably 10% or less, more preferably 7% or less, still more preferably 5% or less, and particularly preferably 4% or less. The lower limit of the light transmittance at a wavelength of 450 nm is 0%.

[0023] The variation ratio of the light transmittance at a wavelength of 380 nm after exposing the pressure-sensitive adhesive film of the present invention to an environment of a temperature of 85°C and a relative humidity of 85% for 240 hours (hereinafter, may be referred to as "the variation ratio of the light transmittance at a wavelength of 380 nm after humidification") is not particularly limited, but from the viewpoint of weather resistance, 0.9 to 1.2 is preferable, more preferably 0.95 to 1.2, still more preferably 1 to 1.19, and particularly preferably 1.07 to 1.19. By the variation ratio of the light transmittance being within the above range, it is possible to prevent the OLED element from deteriorating over time due to ultraviolet rays contained in external light even in the presence of high temperature and high humidity.

[0024] The above-mentioned variation ratio of the light transmittance at a wavelength of 380 nm after humidification can be calculated from the following formula. Variation ratio of the light transmittance at a wavelength of 380 nm after humidification = (Light transmittance at a wavelength of 380 nm after humidification) / (Initial light transmittance at a wavelength of 380 nm)

[0025] In the pressure-sensitive adhesive film of the present invention, the variation ratio of the light transmittance at wavelengths of 450 nm, 550 nm, and 650 nm after exposure to an environment of a temperature of 85°C and a relative humidity of 85% for 240 hours is not particularly limited as long as it is 0.9 to 1.2. The fact that the variation ratio of the light transmittance is within the above range in the visible light region such as 450 nm, 550 nm, and 650 nm is effective from the viewpoint that the decrease in the light extraction effect over time in the pressure-sensitive adhesive film does not occur. The variation ratios of the light transmittance at wavelengths of 450 nm, 550 nm, and 650 nm after the above humidification may be the same or different, preferably 0.93 to 1.15, more preferably 0.95 to 1.1, and still more preferably 0.97 to 1.05. The variation ratio of the light transmittance can be calculated in the same manner as the formula described for the "variation ratio of the light transmittance at a wavelength of 380 nm after humidification".

[0026] In the pressure-sensitive adhesive film of the present invention, the variation ratio of the light transmittance at a wavelength of 380 nm after exposure to an environment of a temperature of 60°C and a relative humidity of 90% for 240 hours is not particularly limited, but from the viewpoint of weather resistance, it is preferably 0.9 to 1.2, more preferably 0.91 to 1.18, still more preferably 0.92 to 1.16, and particularly preferably 0.93 to 1.14. By the variation ratio of the light transmittance being within the above range, it is possible to prevent the OLED element from deteriorating over time due to ultraviolet rays contained in external light even in the presence of high temperature and high humidity. The variation ratio of the light transmittance can be calculated in the same manner as the formula described for the "variation ratio of the light transmittance at a wavelength of 380 nm after humidification".

[0027] In the pressure-sensitive adhesive film of the present invention, the variation ratio of the light transmittance at a wavelength of 380 nm after exposure to an environment of a temperature of 60°C and a relative humidity of 95% for 240 hours is not particularly limited, but from the viewpoint of weather resistance, it is preferably 0.9 to 1.2, more preferably 0.95 to 1.18, still more preferably 1 to 1.16, and particularly preferably 1.03 to 1.14. By the variation ratio of the light transmittance being within the above range, even in the presence of high temperature and high humidity, it is possible to prevent the OLED element from deteriorating over time due to ultraviolet rays contained in external light. The variation ratio of the light transmittance can be calculated by the same method as the formula described in the above "variation ratio of the light transmittance at a wavelength of 380 nm after humidification".

[0028] In the pressure-sensitive adhesive film of the present invention, the method for adjusting the light transmittance and the variation ratio of the light transmittance at a specific wavelength (for example, 380 nm, 450 nm, etc.) is not particularly limited. For example, it can be adjusted by the composition of the layer constituting the optical element. Specifically, the type, monomer composition, degree of crosslinking, thickness of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer can be adjusted. In particular, as the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer, it can be adjusted by using the acrylic-based pressure-sensitive adhesive composition described later or by containing an ultraviolet absorber.

[0029] In the pressure-sensitive adhesive film of the present invention, the impact force (N) in the ball drop test is not particularly limited, but it is preferably 1500 N or less, more preferably 1400 N or less, still more preferably 1300 N or less. The lower limit value of the impact force (N) is not particularly limited, but it is preferably 100 N, more preferably 500 N. The impact force (N) in the ball drop test can be measured, for example, by the method described in the examples.

[0030] The thickness of the pressure-sensitive adhesive film of the present invention is not particularly limited. For example, it is preferably 10 μm to 2 mm, more preferably 15 μm to 1 mm, still more preferably 20 to 500 μm, and particularly preferably 20 to 200 μm.

[0031] In addition, in this specification, the "adhesive film" shall include the meanings of "adhesive sheet" and "adhesive tape". That is, the adhesive film of the present invention may be an adhesive sheet or an 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 adhesive layer with a high refractive index.

[0032] The adhesive film of the present invention may be a so-called "substrate-less type" adhesive film that does not have a substrate (corresponding to the "resin layer" described later), or may be an adhesive film of a type having a substrate. In addition, in this specification, the "substrate-less type" adhesive film may be referred to as a "substrate-less adhesive film", and the adhesive film of the type having a substrate may be referred to as an "adhesive film with a substrate". Examples of the above-mentioned substrate-less adhesive film include a double-sided adhesive sheet composed only of an adhesive layer. The adhesive layer in the above-mentioned double-sided adhesive sheet may be composed of a single layer or may have a multi-layer structure of two or more layers. Examples of the above-mentioned adhesive film with a substrate include 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, and the like. The adhesive layer in the above-mentioned single-sided adhesive film may be composed of a single layer or may have a multi-layer structure of two or more layers. Also, the two adhesive layers may be formed continuously or may be formed independently (that is, via other layers). One of the adhesive layers in the above-mentioned double-sided adhesive film may be composed of a single layer or may have a multi-layer structure of two or more layers. Also, the two adhesive layers may be formed continuously or may be formed independently (that is, via other layers). Also, the other adhesive layer may be composed of a single layer or may have a multi-layer structure of two or more layers. Also, the two adhesive layers may be formed continuously or may be formed independently (that is, via other layers). The above-mentioned "substrate" refers to a support, and when the adhesive film of the present invention is used (attached) to an adherend, it is the part that is attached to the adherend together with the adhesive layer. The release liner that is peeled off when the adhesive film is used (attached) is not included in the above-mentioned substrate.

[0033] Hereinafter, each component of the adhesive film of the present invention will be described.

[0034] (OLED display panel) The OLED display panel used in the OLED display device of the present invention includes, as an essential component, an OLED element in which an anode, an OLED layer including a light-emitting layer, and a cathode are laminated in this order. An optical laminate is laminated on the viewing side of the OLED element of the OLED display panel.

[0035] 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. FIG. 1 is a schematic cross-sectional view showing an embodiment of the OLED display panel.

[0036] As shown in FIG. 1, the OLED display panel 100 includes a transparent electrode 11a, a red OLED layer 10R that emits red light, a red OLED element 12R in which a back electrode 11b is laminated in this order, a transparent electrode 11a, a green OLED layer 10G that emits green light, and a green OLED element 12G in which a back electrode 11b is laminated in this order, a transparent electrode 11a, a blue OLED layer 10B that emits blue light, and a blue OLED element 12B in which a back electrode 11b is laminated in this order. The OLED elements 12R, 12G, 12B of each plurality of colors are arranged in order on the substrate 13. A TFT (Thin Film Transistor) layer 14 is formed on the surface of the substrate 13 where each OLED element is arranged, and is connected to the back electrodes 11b of the OLED elements 12R, 12G, 12B of each plurality of colors.

[0037] In the OLED display panel 100 of FIG. 1, a color filter 15 is arranged on the viewing side (the upper side in FIG. 1) of the OLED elements 12R, 12G, 12B of each plurality of 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.

[0038] In FIG. 1, the color filter 15 has a red coloring layer 15R, a green coloring layer 15G, and a blue coloring layer 15B, which are arranged to face the red OLED element 12R, the green OLED element 12G, and the blue OLED element 12B, respectively.

[0039] The transparent electrode 11a is either a cathode or an anode, but is generally provided as a cathode. As the 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.

[0040] The back electrode 11b functions as the counter electrode of the transparent electrode 11a. The back electrode 11b is either an anode or a cathode, but is generally provided as an anode on the substrate 13. Examples of the forming material include metals such as gold, silver, and chromium. Therefore, the back electrode 11b can reflect light.

[0041] A bonding layer 17 is provided between the substrate 13 and the color filter 15. The bonding layer 17 has light transmittance. As the material of the bonding layer 17, materials generally used in an OLED display device may be used. For example, photocurable resins such as photosensitive polyimide resins or thermosetting resins can be used.

[0042] In addition to the configuration shown in FIG. 1, the OLED display panel 100 may have configurations 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. (not shown).

[0043] The feature of the OLED display panel in Fig. 1 is that a color filter 15 is arranged such that color layers 15R, 15G, and 15B of the same color face the OLED elements 12R, 12G, and 12B of each plurality of colors, respectively. As shown in Fig. 1, external light W that is white passes through, for example, the red color layer 15R, further passes through the transparent electrode 11a and the red OLED layer 10R that emits red light, is reflected by 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 the reflected light G enters the observer's eye.

[0044] Since the external light W is absorbed by the red color layer 15R for green and blue, the light intensity becomes 1 / 3. Also, since the reflected light G passes through the red color layer 15R and the red OLED layer 10R again, attenuation occurs thereby. Also, since the reflected light G exhibits red, the red light emitted from the OLED layer 10R can be enhanced. Similarly, when the external light W is incident on the green color layer 15G and the blue color layer 15B, green light and blue light can be enhanced respectively. Therefore, by using a color filter in combination with the OLED display panel, even when a polarizing plate is not used for antireflection, the reflection of external light can be significantly suppressed and the emission luminance of the OLED element can be improved.

[0045] However, the color filter is likely to cause interference unevenness due to a regular two-dimensional structure. Also, the color filter has a problem that reflection easily occurs at the interface and the light collection rate of the light from the OLED element decreases. Also, the color filter has a problem that the ultraviolet absorption function is not sufficient compared to the case of using a polarizing plate, and the OLED element is likely to deteriorate over time (i.e., has low weather resistance) due to the ultraviolet rays contained in the external light. Also, the color filter has a problem that the shock absorption function is not sufficient compared to the case of using a polarizing plate.

[0046] In addition, the OLED display panel 100 of this embodiment has a microcavity structure. The light generated from the OLED layers 10R, 10G, and 10B passes through the transparent electrode 11a and is emitted to the outside. Here, the emitted light includes both a "direct light" that is directly emitted from the OLED layers 10R, 10G, and 10B toward the transparent electrode 11a and a "reflected light" that is emitted from the OLED layers 10R, 10G, and 10B toward the back electrode 11b, reflected by the back electrode 11b, and then travels toward the transparent electrode 11a. That is, a part of the light emitted from the OLED layers 10R, 10G, and 10B travels toward the transparent electrode 11a without traveling toward the back electrode 11b side, and is emitted to the outside through the transparent electrode 11a, forming a first optical path C1. 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, forming a second optical path C2. Due to the interference between this direct light and the reflected light, the respective thicknesses of the OLED layers 10R, 10G, and 10B are made different so that the light components corresponding to each color reinforce each other. That is, the optical path lengths between the back electrode (positive electrode) 11b and the transparent electrode (negative electrode) 11a are matched to the respective EL spectral peak wavelengths of red, green, and blue, and the respective thicknesses of the OLED layers 10R, 10G, and 10B are made different so as to extract the strongest light from each color. Specifically, the thickness of the short-wavelength blue OLED layer 10B is designed to be thin, and the thickness of the long-wavelength red OLED layer 10R is designed to be thick. When the light generated in the OLED layer repeats reflection between the positive electrode and the negative electrode, only the light with a wavelength that matches the optical path length is resonated and enhanced, and the light of other wavelengths with a deviation in the optical path length is weakened, so that the spectrum of the light extracted to the outside becomes steep and high-intensity, improving the luminance and color purity.

[0047] According to an OLED display panel having a microcavity structure, while an excellent effect of improving the luminance and color purity can be obtained, there may occur a problem that the viewing angle dependence is strong (the viewing angle is narrow) because the spectrum is steep. For this reason, when an image is viewed obliquely during image display, a color shift may occur in which the image appears to be a color different from the color that is originally intended to be displayed.

[0048] (Optical element) The optical element is an optical element laminated on the viewing side of the OLED display device and includes at least an adhesive layer. The 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 those with a polarization degree exceeding 95% such as a polarizing plate.

[0049] (Adhesive layer) The adhesive layer refers to a layer that has adhesiveness at normal temperature and adheres to an adherend under a light pressure, and also refers to a layer that retains a practical adhesive force even when the adherend adhered to the adhesive layer is peeled off.

[0050] 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 preferably has a high refractive index. The refractive index of the adhesive layer is preferably 1.57 or more, more preferably 1.575 or more, still more preferably 1.580 or more, particularly preferably 1.585 or more, even more preferably 1.590 or more, and may be 1.595 or more.

[0051] 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 below.

[0052] The adhesive layer is not particularly limited, but preferably has a light scattering characteristic (function of scattering light) from the viewpoint of efficiently reducing color shift and interference unevenness of the OLED display device.

[0053] When the OLED display device includes a color filter on the viewing side, from the viewpoint 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, still more preferably 500 μm or less, and most preferably 0 μm, that is, the adhesive layer and the color filter are in direct contact.

[0054] The distance between the adhesive layer and the color filter indicates 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 another layer is laminated between the adhesive layer and the color filter, it corresponds to the thickness (μm) of the other layer (the total in the case of two or more layers).

[0055] The haze value of the adhesive layer is not particularly limited. From the viewpoint of efficiently reducing color shift and interference unevenness of the OLED display device, 20% or more is preferable, more preferably 30% or more, still more preferably 40% or more, and particularly preferably 50% or more. Also, 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 still more preferably 70% or less.

[0056] The total light transmittance of the adhesive layer is not particularly limited. From the viewpoint of ensuring the luminance of the OLED display device, 60% or more is preferable, more preferably 70% or more, still more preferably 80% or more, and particularly preferably 90% or more. Also, 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.

[0057] The haze value and the total light transmittance of the adhesive layer can be measured by the methods defined in JIS 7136 and JIS 7361, respectively, and can be controlled by the type and thickness of the adhesive layer, the type and blending amount of the light-scattering fine particles described later, and the like.

[0058] The adhesive layer has a peak of the loss factor (tanδ) in the region of 0°C or lower, and it is preferable that the peak top value of the peak is 1.5 or more. More preferably, the above loss factor is 1.8 or more, still more preferably 2.0 or more, and particularly preferably 2.2 or more. The maximum value of the above loss factor is not particularly limited, but for example, 5.0 is preferable, and more preferably 3.0. When the adhesive layer is composed of two or more continuous multi-layer adhesive layers, the loss factor (tanδ) of the adhesive layer is measured by regarding the two or more adhesive layers as one adhesive layer. When the loss factor of the adhesive layer is within the above range, the impact resistance tends to be improved.

[0059] The thickness of the adhesive layer is not particularly limited, but from the viewpoint of improving the impact resistance, it is preferably 10 to 500 μm, more preferably 15 to 300 μm, still more preferably 15 to 200 μm, still more preferably 20 to 100 μm, and particularly preferably 20 to 40 μm. When the adhesive layer is composed of two or more adhesive layers, the thickness of the adhesive layer is the total thickness of the two or more adhesive layers.

[0060] The adhesive layer may contain light-scattering fine particles. The light-scattering fine particles have an appropriate refractive index difference from the adhesive layer and impart light-scattering characteristics to the adhesive layer. Examples of the light-scattering fine particles include inorganic fine particles and polymer fine particles. Examples of the material of the inorganic fine particles include silica, calcium carbonate, etc. Examples of the material of the polymer fine particles include silicone resin, acrylic resin, methacrylic resin (for example, polymethyl methacrylate), etc. The light-scattering fine particles may be used alone or in combination of two or more.

[0061] The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is not particularly limited. For example, acrylic pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives, vinyl alkyl ether-based pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, polyester-based pressure-sensitive adhesives, polyamide-based pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, fluorine-based pressure-sensitive adhesives, epoxy-based pressure-sensitive adhesives, etc. may be mentioned. Among them, as the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer, acrylic pressure-sensitive adhesives are preferred in terms of transparency, adhesiveness, weather resistance, cost, and ease of designing the pressure-sensitive adhesive. That is, the pressure-sensitive adhesive layer is preferably an acrylic pressure-sensitive adhesive layer composed of an acrylic pressure-sensitive adhesive. The pressure-sensitive adhesive can be used alone or in combination of two or more.

[0062] The acrylic pressure-sensitive adhesive layer contains an acrylic polymer as a base polymer. The acrylic polymer is a polymer containing an acrylic monomer (a monomer having a (meth)acryloyl group in the molecule) as a monomer component constituting the polymer. The acrylic polymer is preferably a polymer containing an alkyl (meth)acrylate as a monomer component constituting the polymer. The acrylic polymers can be used alone or in combination of two or more.

[0063] The pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer may be in any form. For example, the pressure-sensitive adhesive composition may be an emulsion type, a solvent type (solution type), an active energy ray-curing type, a hot melt type (hot melt type), etc. Among them, from the viewpoints of productivity and the ease of obtaining a pressure-sensitive adhesive layer excellent in optical properties and appearance properties, solvent-type and active energy ray-curing type pressure-sensitive adhesive compositions are preferred. That is, the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive layer containing an acrylic polymer as a base polymer, and is preferably formed by a solvent-type or active energy ray-curing type acrylic pressure-sensitive adhesive composition.

[0064] Examples of the pressure-sensitive adhesive composition (acrylic pressure-sensitive adhesive composition) for forming the acrylic pressure-sensitive adhesive layer include, for example, an acrylic pressure-sensitive adhesive composition containing an acrylic polymer as an essential component, or an acrylic pressure-sensitive adhesive composition containing, as an essential component, a mixture of monomers (monomers) constituting the acrylic polymer (which may be referred to as a "monomer mixture") or a partial polymer thereof. Examples of the former include so-called solvent-type acrylic pressure-sensitive adhesive compositions. Examples of the latter include so-called active energy ray-curable acrylic pressure-sensitive adhesive compositions. The "monomer mixture" means a mixture containing monomer components constituting the polymer. The "partial polymer" may also be referred to as a "prepolymer" and means a composition in which one or more monomer components among the monomer components in the monomer mixture are partially polymerized.

[0065] The acrylic polymer is a polymer formed by using an acrylic monomer as an essential monomer component (monomer component). The acrylic polymer is preferably a polymer formed by using 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" represents "acrylic" and / or "methacrylic" (either one or both of "acrylic" and "methacrylic"), and the same applies to others. The acrylic polymer is composed of one or more monomer components.

[0066] Examples of the alkyl (meth)acrylate as the essential monomer component preferably include an alkyl (meth)acrylate having a linear or branched alkyl group. The alkyl (meth)acrylate can be used alone or in combination of two or more.

[0067] The alkyl (meth)acrylate having a linear or branched alkyl group is not particularly limited. For example, linear or branched alkyl (meth)acrylates having 1 to 20 carbon atoms such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc. are mentioned. Among them, the alkyl (meth)acrylate having a linear or branched alkyl group is preferably an alkyl (meth)acrylate having a linear or branched alkyl group with 4 to 18 carbon atoms, more preferably butyl acrylate. The alkyl (meth)acrylate having a linear or branched alkyl group can be used alone or in combination of two or more.

[0068] The proportion of the alkyl (meth)acrylate in all monomer components (100% by weight) constituting the acrylic polymer is not particularly limited, but is preferably 50% by weight or more (for example, 50 to 100% by weight), more preferably 60 to 99.5% by weight, and still more preferably 70 to 99% by weight.

[0069] The acrylic polymer may contain a copolymerizable monomer as a monomer component constituting the polymer together with the alkyl (meth)acrylate. That is, the acrylic polymer may contain a copolymerizable monomer as a structural unit. The copolymerizable monomer can be used alone or in combination of two or more.

[0070] The copolymerizable monomer is not particularly limited, but by using a monomer having an aromatic ring in the molecule, an adhesive layer with a high refractive index can be obtained, interfacial reflection with the OLED display panel can be suppressed, and the light collection rate from the OLED element can be improved. The 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" may be referred to as an "aromatic ring-containing monomer".

[0071] 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 kind of such a compound can be used alone or in combination of two or more kinds. Examples of the ethylenically unsaturated group include a (meth)acryloyl group, a vinyl group, a (meth)allyl group, etc. From the viewpoint of polymerization reactivity, a (meth)acryloyl group is preferable, and from the viewpoints of flexibility and adhesiveness, an acryloyl group is more preferable. From the viewpoint of suppressing a decrease in the flexibility of the adhesive, as the aromatic ring-containing monomer, a compound having one ethylenically unsaturated group in one molecule (that is, a monofunctional monomer) is preferably used.

[0072] The copolymerizable monomer is not particularly limited, but from the viewpoints of suppressing clouding in a high-humidity environment, improving durability, compatibility with various additives such as ultraviolet absorbers, and transparency, monomers having a nitrogen atom in the molecule or monomers having a hydroxyl group in the molecule are preferably mentioned.

[0073] The monomer having a nitrogen atom in the molecule is a monomer (monomer) having at least one nitrogen atom in the molecule (within one molecule). In this specification, the "monomer having a nitrogen atom in the molecule" may be referred to as a "nitrogen atom-containing monomer". The nitrogen atom-containing monomer is not particularly limited, but cyclic nitrogen-containing monomers, (meth)acrylamides, etc. are preferably mentioned. Note that the nitrogen atom-containing monomers can be used alone or in combination of two or more kinds.

[0074] The cyclic nitrogen-containing monomer is not particularly limited as long as it has a polymerizable functional group having an unsaturated double bond such as a (meth)acryloyl group or a vinyl group and has a cyclic nitrogen structure. The cyclic nitrogen structure preferably has a nitrogen atom in the cyclic structure. Examples of the cyclic nitrogen-containing monomer include N-vinyl cyclic amide (lactam-based vinyl monomer), vinyl-based monomers having a nitrogen-containing heterocyclic ring, and the like.

[0075] The monomer having a hydroxyl group in the molecule is a monomer having at least one hydroxyl group (hydroxyl group) in the molecule, and preferably has a polymerizable functional group having an unsaturated double bond such as a (meth)acryloyl group or a vinyl group and has a hydroxyl group. However, the monomer having a hydroxyl group in the molecule does not include the nitrogen atom-containing monomer. That is, in this specification, a monomer having both a nitrogen atom and a hydroxyl group in the molecule is included in the "nitrogen atom-containing monomer". In this specification, the "monomer having a hydroxyl group in the molecule" may be referred to as a "hydroxyl group-containing monomer". The hydroxyl group-containing monomer can be used alone or in combination of two or more.

[0076] Examples of the hydroxyl group-containing monomer include hydroxyl group-containing (meth)acrylic acid esters such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; vinyl alcohol; allyl alcohol and the like. Among them, the hydroxyl group-containing monomer is preferably a hydroxyl group-containing (meth)acrylic acid ester, more preferably 2-hydroxyethyl acrylate (HEA) and 4-hydroxybutyl acrylate (4HBA).

[0077] 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 monomer components (100% by weight) constituting the acrylic polymer is not particularly limited, but from the viewpoints of suppressing clouding in a high-humidity environment and improving durability, it is preferably 0.001 to 5% by weight, more preferably 0.01 to 3% by weight, and still more preferably 0.03 to 1% by weight.

[0078] Examples of copolymerizable monomers other than the nitrogen atom-containing monomer and the hydroxyl group-containing monomer include alicyclic structure-containing monomers, polyfunctional monomers, (meth)acrylic acid alkoxyalkyl esters, carboxy group-containing monomers, epoxy group-containing monomers, and the like. Examples of the carboxy group-containing monomer include (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.

[0079] When the acrylic polymer contains the carboxy group-containing monomer as a monomer component constituting the polymer, the proportion of the carboxy group-containing monomer in all monomer components (100% by weight) constituting the acrylic polymer is not particularly limited, but is preferably 0.1 to 30% by weight, more preferably 0.5 to 20% by weight.

[0080] The content of the base polymer (particularly acrylic polymer) in the pressure-sensitive adhesive layer is not particularly limited, but is preferably 50% by weight or more (for example, 50 to 100% by weight), more preferably 80% by weight or more (for example, 80 to 100% by weight), and still more preferably 90% by weight or more (for example, 90 to 100% by weight) based on 100% by weight of the total weight of the pressure-sensitive adhesive layer.

[0081] The base polymer such as the acrylic polymer contained in the adhesive layer is obtained by polymerizing monomer components. Although this polymerization method is not particularly limited, for example, solution polymerization method, emulsion polymerization method, bulk polymerization method, polymerization method by irradiation with active energy rays (active energy ray polymerization method), etc. can be mentioned.

[0082] When polymerizing the above monomer components, polymerization initiators such as solvents, thermal polymerization initiators, and photopolymerization initiators (photoinitiators) may be used according to the type of polymerization reaction. Note that the polymerization initiator can be used alone or in combination of two or more.

[0083] The thermal polymerization initiator is not particularly limited, and examples include azo-based polymerization initiators, peroxide-based polymerization initiators (for example, dibenzoyl peroxide, tert-butyl permaleate, etc.), redox-based polymerization initiators, etc. Among them, the azo-based polymerization initiator disclosed in JP-A-2002-69411 is preferable. Examples of the azo-based polymerization initiator include 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2-methylpropionic acid) dimethyl, 4,4'-azobis-4-cyanovaleric acid, etc. Note that the thermal polymerization initiator can be used alone or in combination of two or more.

[0084] When using the azo-based polymerization initiator during the polymerization of the acrylic polymer, the usage amount of the azo-based polymerization initiator is not particularly limited. For example, it is preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, based on 100 parts by weight of all monomer components constituting the acrylic polymer, and preferably 0.5 parts by weight or less, more preferably 0.3 parts by weight or less.

[0085] The photopolymerization initiator is not particularly limited, and examples include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, etc. The photopolymerization initiator can be used alone or in combination of two or more.

[0086] When the photoinitiator is used during the polymerization of the acrylic polymer, the amount of the photoinitiator used is not particularly limited. For example, it is preferably 0.01 parts by weight or more, more preferably 0.1 parts by weight or more, based on 100 parts by weight of all the monomer components constituting the acrylic polymer. Also, it is preferably 3 parts by weight or less, more preferably 1.5 parts by weight or less.

[0087] The adhesive layer may contain an ultraviolet absorber (UVA). When the adhesive layer contains an ultraviolet absorber, it is possible to suppress the deterioration of the OLED element due to ultraviolet rays contained in external light and obtain an OLED display device having excellent weather resistance without using a polarizing plate. Also, it is possible to suppress the deterioration of the high refractive index component due to ultraviolet rays and maintain a high light collection rate. Note that the ultraviolet absorber can be used alone or in combination of two or more.

[0088] The ultraviolet absorber is not particularly limited. For example, benzotriazole-based ultraviolet absorbers, hydroxyphenyltriazine-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, salicylic acid ester-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, oxybenzophenone-based ultraviolet absorbers, etc. can be mentioned. As the ultraviolet absorber, at least one ultraviolet absorber selected from the group consisting of benzotriazole-based ultraviolet absorbers, hydroxyphenyltriazine-based ultraviolet absorbers, and benzophenone-based ultraviolet absorbers is preferable in terms of having high ultraviolet absorption, excellent optical properties, ease of obtaining an adhesive layer having high transparency, and having excellent light stability.

[0089] Examples of the benzotriazole-based ultraviolet absorber (benzotriazole-based compound) include 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole, benzenepropanoic acid, and 3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy (C 7-9Examples thereof include ester compounds of (side-chain and linear alkyl), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, and the like.

[0090] Examples of the hydroxyphenyltriazine-based ultraviolet absorber (hydroxyphenyltriazine-based compound) include, for example, 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-hydroxyphenyl and [(C 10-16 (mainly C 12-13 ) alkyloxy)methyl]oxirane reaction product, 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, and the like.

[0091] Examples of the benzophenone-based ultraviolet absorber (benzophenone-based compound) and the oxybenzophenone-based ultraviolet absorber (oxybenzophenone-based compound) include, for example, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (anhydrous and trihydrate salts), 2-hydroxy-4-octyloxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, and the like.

[0092] 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. However, from the viewpoint of suppressing the deterioration of the OLED element due to ultraviolet rays contained in external light and obtaining an OLED display device having excellent weather resistance 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 still more preferably 0.1 part by weight or more with respect to 100 parts by weight of the base polymer (for example, an acrylic polymer). Further, 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 still more preferably 8 parts by weight or less with respect to 100 parts by weight of the acrylic polymer from the viewpoint of suppressing the occurrence of yellowing of the adhesive due to the addition of the ultraviolet absorber and obtaining excellent optical properties, high transparency, and excellent appearance properties.

[0093] The adhesive layer may contain a dye compound (for example, a dye compound having a maximum absorption wavelength of the absorption spectrum in the wavelength region of 380 to 430 nm) instead of the ultraviolet absorber or in combination with the ultraviolet absorber. Also, the dye compound can suppress the deterioration of the OLED element and the deterioration of the high refractive index component due to ultraviolet light.

[0094] The above pigment compound may be used alone or in combination of two or more. When only the pigment compound is used, the content of the pigment compound as a whole is preferably 0.005 parts by weight or more, more preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight or more, still more preferably 0.1 parts by weight or more, and particularly preferably 0.2 parts by weight or more, based on 100 parts by weight of the base polymer (for example, an acrylic polymer). Also, based on 100 parts by weight of the acrylic polymer, 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, still more preferably 5 parts by weight or less, and particularly preferably 2 parts by weight or less. By setting the addition amount of the pigment compound within the above range, light in a region that does not affect the light emission of the OLED element can be sufficiently absorbed, and by using the adhesive layer formed from the adhesive composition, deterioration of the OLED element and deterioration of the high refractive index component can be suppressed, which is preferable.

[0095] Either the above ultraviolet absorber or the pigment compound can be used, but it is preferable to use the ultraviolet absorber and the pigment compound in combination. According to the ultraviolet absorber, although it can absorb light with a wavelength of 380 nm, for example, light in the wavelength region (380 to 430 nm) shorter than the light emission region (longer wavelength side than 430 nm) of the OLED element is not sufficiently absorbed, and deterioration may occur due to the transmitted light. The pigment compound can suppress the transmission of light with a wavelength (380 to 430 nm) shorter than the light emission region (longer wavelength side than 430 nm) of the OLED element. By using the ultraviolet absorber and the pigment compound in combination, the light transmittance of visible light in the light emission region of the OLED element can be sufficiently ensured.

[0096] In the present invention, by using such a combination of a dye compound and an ultraviolet absorber, light in a region that does not affect the light emission of the OLED element (wavelength 380 to 430 nm) can be sufficiently absorbed, and the light emission region of the OLED element (longer wavelength side than 430 nm) can be sufficiently transmitted. As a result, it is possible to simultaneously suppress the deterioration due to external light and the deterioration of the high refractive index component of the OLED element. When the ultraviolet absorber and the dye compound are used in combination, the ultraviolet absorber is preferably 0.1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, and still more preferably 0.5 to 3 parts by weight with respect to 100 parts by weight of the base polymer (for example, an acrylic polymer). The dye compound is preferably 0.1 to 20 parts by weight, more preferably 0.1 to 10 parts by weight, and still more preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the base polymer (for example, an acrylic polymer).

[0097] The maximum absorption wavelength of the dye compound means the absorption maximum wavelength showing the maximum absorbance among a plurality of absorption maxima in the spectral absorption spectrum in the wavelength region of 300 to 460 nm. The maximum absorption wavelength of the absorption spectrum of the dye compound more preferably exists in the wavelength region of 380 to 420 nm. Further, the dye compound is not particularly limited as long as it has the above wavelength characteristics, but a material having no fluorescence and phosphorescence performance (photoluminescence) that does not inhibit the display performance of the OLED element is preferred.

[0098] Examples of the dye compound include organic dye compounds such as azomethine compounds, indole compounds, cinnamic acid compounds, pyrimidine compounds, porphyrin compounds, and cyanine compounds.

[0099] As the organic pigment compound, commercially available ones can be preferably used. Specifically, as the indole compound, BONASORB UA3911 (trade name, maximum absorption wavelength of absorption spectrum: 398 nm, manufactured by Orient Chemical Industries, Ltd.), as the cinnamic acid compound, SOM-5-0106 (trade name, maximum absorption wavelength of absorption spectrum: 416 nm, manufactured by Orient Chemical Industries, Ltd.), as the porphyrin compound, FDB-001 (trade name, maximum absorption wavelength of absorption spectrum: 420 nm, manufactured by Yamada Chemical Industry Co., Ltd.), as the cyanine compound, a merocyanine compound (trade name: FDB-009, maximum absorption wavelength of absorption spectrum: 394 nm, manufactured by Yamada Chemical Industry Co., Ltd.), etc. can be mentioned. Among them, from the viewpoints of crosslinking inhibition suppression and optical reliability, cyanine compounds are preferable, and polymethine compounds are particularly preferable.

[0100] Examples of the pigment compound include, for example, a compound represented by the following formula (1A) which is a cyanine compound (hereinafter, may be referred to as compound (1A)). When geometric isomers exist in the compound (1A), the compound (1A) includes any of its geometric isomers. Further, when one or more asymmetric carbon atoms exist in the compound (1A), the compound (1A) includes any of a compound in which each asymmetric carbon atom has an R configuration, a compound in which each asymmetric carbon atom has an S configuration, and any combination of them. Also included are any of these racemic compounds, racemic mixtures, single enantiomers, and diastereomer mixtures.

[0101]

Chemical formula

[0102] In formula (1A), m represents an integer from 1 to 6. Q 1 represents a hydrogen atom when m is 1, and represents a divalent to hexavalent linking group when m is 2 to 6. D 1 represents a group in which one hydrogen atom is removed from a compound represented by the following formula (2A) (hereinafter, may be referred to as compound (2A)).

[0103]

Chemical formula

[0104] 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 ring-containing group, -C(O)-R 7 or -SO2-R 8 represents. R 7 represents a hydroxy group or -OR 71 represents, and R 8 represents a halogen atom, a hydroxy group, -OR 81 , -NR 82 R 83 or -R 84 represents. 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 represents, and 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 and R 405 and R 404 and the nitrogen atom to which R 405 is bonded may form a 4- to 8-membered nitrogen-containing heterocyclic ring (a heterocyclic ring containing a nitrogen atom as a ring-constituting atom) which may have a substituent.

[0105] Although the preferred embodiments and production methods of compound (1A) are not particularly limited, for example, they can be produced by the method described in JP-A-2018-200463.

[0106] The pressure-sensitive adhesive layer may contain a light stabilizer. When the pressure-sensitive adhesive layer contains a light stabilizer, it is particularly preferable to contain a light stabilizer together with the ultraviolet absorber. Since the light stabilizer can capture radicals generated by photooxidation, the resistance of the pressure-sensitive adhesive layer to light (especially ultraviolet light) can be improved. Note that the light stabilizer can be used alone or in combination of two or more.

[0107] The light stabilizer is not particularly limited, and examples thereof include phenolic light stabilizers (phenolic compounds), phosphorus-based light stabilizers (phosphorus-based compounds), thioether-based light stabilizers (thioether-based compounds), amine-based light stabilizers (amine-based compounds) (especially hindered amine-based light stabilizers (hindered amine-based compounds)), and the like.

[0108] A crosslinking agent may be used for forming the pressure-sensitive adhesive layer. For example, the acrylic polymer in the acrylic pressure-sensitive adhesive layer can be crosslinked to control the gel fraction. Note that the crosslinking agent can be used alone or in combination of two or more.

[0109] The crosslinking agent is not particularly limited, and examples thereof include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, and urea-based crosslinking agents. Among them, isocyanate-based crosslinking agents and epoxy-based crosslinking agents are preferable.

[0110] When a crosslinking agent is used for forming the adhesive layer, the amount of the crosslinking agent used is not particularly limited, but from the viewpoint of obtaining sufficient adhesion reliability, it is preferably 0.001 part by weight or more, more preferably 0.01 part by weight or more, based on 100 parts by weight of the base polymer. Further, the upper limit of the amount used 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, from the viewpoint of obtaining appropriate flexibility in the adhesive layer and improving the adhesive strength.

[0111] The adhesive layer (particularly, an acrylic adhesive layer) may contain a silane coupling agent from the viewpoint of improving the adhesion reliability under humid conditions, particularly improving the adhesion reliability to glass. The silane coupling agent can be used alone or in combination of two or more. When the adhesive layer contains a silane coupling agent, the adhesiveness under humid conditions, particularly the adhesiveness to glass, can be improved.

[0112] The silane coupling agent is not particularly limited, and examples thereof include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-phenyl-aminopropyltrimethoxysilane, and the like. Further, examples of the silane coupling agent also include commercially available products such as the product name "KBM-403" (manufactured by Shin-Etsu Chemical Co., Ltd.). Among them, γ-glycidoxypropyltrimethoxysilane is preferable as the silane coupling agent.

[0113] When the adhesive layer contains a silane coupling agent, the content of the silane coupling agent in the adhesive layer (particularly, an acrylic adhesive layer) is not particularly limited, but it is preferably 0.01 part by weight or more, more preferably 0.02 part by weight or more, based on 100 parts by weight of the base polymer. Further, 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, based on 100 parts by weight of the base polymer.

[0114] The adhesive layer may further contain, if necessary, additives such as a crosslinking accelerator, tackifier resins (rosin derivatives, polyterpene resins, petroleum resins, oil-soluble phenols, etc.), anti-degradants, fillers, colorants (pigments, dyes, etc.), antioxidants, chain transfer agents, plasticizers, softeners, surfactants, antistatic agents, etc., as long as the effects of the present invention are not impaired. Such additives can be used alone or in combination of two or more kinds.

[0115] The method for producing the adhesive layer (particularly, an acrylic adhesive layer) is not particularly limited. For example, the adhesive composition is applied (coated) onto a base material (including a resin layer and a glass layer described later) or a release liner, and the obtained adhesive composition layer is dried and cured, or the adhesive composition is applied (coated) onto a base material (including a resin layer and a glass layer described later) or a release liner, and the obtained adhesive composition layer is irradiated with active energy rays for curing. Further, if necessary, heating and drying may be performed.

[0116] Examples of the active energy rays include ionizing radiations such as α-rays, β-rays, γ-rays, neutron rays, electron rays, and ultraviolet rays. In particular, ultraviolet rays are preferable. Further, the irradiation energy, irradiation time, irradiation method, etc. of the active energy rays are not particularly limited.

[0117] The adhesive composition can be produced by a known or conventional method. For example, a solvent-type acrylic adhesive composition can be produced by mixing an additive (for example, an ultraviolet absorber, etc.) with a solution containing the acrylic polymer, if necessary. For example, an active energy ray-curable acrylic adhesive composition can be produced by mixing an additive (for example, an ultraviolet absorber, etc.) with a mixture of the acrylic monomers or a partial polymer thereof, if necessary. In addition, a known coating method may be used for the application (coating) of the adhesive composition. For example, coaters such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, a spray coater, a comma coater, a direct coater, etc. may be used.

[0118] In particular, when forming the adhesive layer with an active energy ray-curable adhesive composition, the active energy ray-curable adhesive composition preferably contains a photoinitiator. When the active energy ray-curable adhesive composition contains an ultraviolet absorber, it is preferable to contain at least a photoinitiator having light absorption characteristics in a wide wavelength range as the photoinitiator. For example, it is preferable to contain at least a photoinitiator having light absorption characteristics not only in ultraviolet light but also in visible light. This is because there is a concern that the action of the ultraviolet absorber may inhibit curing by active energy rays, 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.

[0119] (Adhesive layer) The adhesive layer is a layer that can bond substances by intervening between adherends. When the adherends adhered with the adhesive layer are peeled off, the adhesive layer has no practical adhesive strength.

[0120] As the adhesive for forming the adhesive layer constituting the optical element, various adhesives can be applied. For example, isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl-based latexes, aqueous polyesters, etc. can be mentioned. These adhesives are usually used as adhesives composed of aqueous solutions (aqueous adhesives) and contain 0.5 to 60% by weight of solid content. Among these, polyvinyl alcohol-based adhesives are preferable, and polyvinyl alcohol-based adhesives containing an acetoacetyl group are more preferable.

[0121] The aqueous adhesive may contain a crosslinking agent. As the crosslinking agent, a compound having at least two functional groups reactive with components such as polymers constituting the adhesive in one molecule is usually used. For example, alkylenediamines; isocyanates; epoxies; aldehydes; amino-formaldehydes such as methylol urea and methylol melamine can be mentioned. The blending amount of the crosslinking agent in the adhesive is usually about 10 to 60 parts by weight with respect to 100 parts by weight of components such as polymers constituting the adhesive.

[0122] The adhesive may contain additives. Examples of the additives include 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 suppressants, antistatic agents, heat stabilizers, hydrolysis-resistant stabilizers, and the like.

[0123] The application of the adhesive may be performed on either one of the two adherends to be adhered, or on both of them. After bonding, a drying process may be performed to form an adhesive layer composed of a coated and dried layer. After the drying process, ultraviolet rays or electron beams can be irradiated as necessary. The thickness of the adhesive layer is not particularly limited. When an aqueous adhesive or the like is used, it is preferably about 30 to 5000 nm, more preferably about 100 to 1000 nm. When an ultraviolet-curable adhesive, an electron beam-curable adhesive, or the like is used, it is preferably about 0.1 to 100 μm, more preferably about 0.5 to 10 μm.

[0124] (Resin layer) The resin layer constituting the optical element is not particularly limited, and examples thereof include plastic films. Examples of the materials such as the plastic film include polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) that are excellent in dimensional stability and difficult to shrink, cyclic olefin polymers (COP), polycarbonate (PC), polyether ether ketone (PEEK), and transparent polyimide (CPI). These plastic materials can be used alone or in combination of two or more. The release liner peeled off during the use (attachment) of the optical element is not included in the "resin layer".

[0125] The resin layer is preferably transparent. The total light transmittance in the visible light wavelength region of the resin layer (in accordance with JIS K 7361-1) is not particularly limited, but is preferably 85% or more, more preferably 88% or more.

[0126] In the present invention, the refractive index difference between the adhesive layer and the resin layer (the absolute value of "refractive index of the adhesive layer" - "refractive index of the resin layer") is not particularly limited. However, from the viewpoint of enhancing the antireflection property at the interface and improving the light collection rate from the OLED element, it is preferably 2 or less, more preferably 1 or less, still more preferably 0.5 or less, and particularly preferably 0.3 or less. When the resin layer has a multi-layer structure of two or more continuous layers, the refractive index difference is measured by regarding the two or more layers as one resin layer.

[0127] The thickness of the resin layer is not particularly limited. For example, it is preferably 10 to 80 μm. Note that the resin layer may have either a single-layer or multi-layer form. Further, known and commonly used surface treatments such as physical treatments like corona discharge treatment and plasma treatment, and chemical treatments like undercoat treatment may be appropriately applied to the surface of the resin layer. When the resin layer has a multi-layer structure of two or more continuous layers, the thickness is measured by regarding the two or more layers as one resin layer.

[0128] The resin layer preferably contains an ultraviolet absorber (UVA) or a dye compound whose maximum absorption wavelength of the absorption spectrum exists in the wavelength range of 380 to 430 nm. When the resin layer contains an ultraviolet absorber or the dye compound, deterioration of the OLED element due to ultraviolet rays contained in external light can be suppressed, and an OLED display device excellent in weather resistance can be obtained without using a polarizing plate. Further, deterioration of the high refractive index component of the adhesive layer due to ultraviolet rays can be suppressed, and a high light collection rate can be maintained. In particular, when the resin layer contains an ultraviolet absorber or the dye compound, the content of the ultraviolet absorber and the dye compound in the adhesive layer can be reduced, and precipitation and bleed-out of the ultraviolet absorber and the dye compound in the adhesive layer can be suppressed, which is preferable.

[0129] As the ultraviolet absorber (UVA) and the dye compound contained in the resin layer, the same ones as those contained in the adhesive layer can be used. Note that the ultraviolet absorber and the dye compound can be used alone or in combination of two or more.

[0130] When the resin layer contains an ultraviolet absorber or the pigment compound, the content of each of the ultraviolet absorber and the pigment compound in the resin layer is not particularly limited. However, in order to suppress the deterioration of the OLED element due to ultraviolet rays contained in external light and obtain an OLED display device excellent in weather resistance without using a polarizing plate, it is preferably 0.01% by weight or more, more preferably 0.05% by weight or more, and still more preferably 0.1% by weight or more based on 100% by weight of the resin layer. Further, the upper limit of the content of the ultraviolet absorber and the pigment compound is preferably 10% by weight or less, more preferably 9% by weight or less, and still more preferably 8% by weight or less based on 100% by weight of the resin layer in order to suppress the occurrence of the yellowing phenomenon of the adhesive accompanying the addition of the ultraviolet absorber and obtain excellent optical properties, high transparency, and excellent appearance properties.

[0131] When both the resin layer and the adhesive layer contain an ultraviolet absorber or the pigment compound, the total amount may be adjusted so as to be within the above range.

[0132] (Glass layer) The glass layer constituting the optical element is not particularly limited, and an appropriate one can be adopted according to the purpose. According to the classification by composition, the glass layer includes, for example, soda-lime glass, borate glass, aluminosilicate glass, quartz glass, etc. According to the classification by alkali component, non-alkali glass and low-alkali glass are included. The content of the alkali metal component (for example, Na2O, K2O, Li2O) of the glass is preferably 15% by weight or less, and more preferably 10% by weight or less.

[0133] The thickness of the glass layer is not particularly limited. However, considering the surface hardness, airtightness, and corrosion resistance of the glass, it is preferably 20 μm or more. Further, the glass layer desirably has flexibility and bendability like a film, and in order to suppress double imaging and enable a clear image to be projected, the thickness is preferably 60 μm or less. The thickness of the glass layer is more preferably 30 μm or more and 55 μm or less, and particularly preferably 40 μm or more and 50 μm or less.

[0134] The method for forming the glass layer is not particularly limited, and an appropriate one can be adopted according to the purpose. Typically, the glass layer can be produced by melting a mixture containing main raw materials such as silica and alumina, defoaming agents such as sodium sulfate and antimony oxide, and reducing agents such as carbon at a temperature of about 1400 to 1600 °C, forming it into a thin plate shape, and then cooling. Examples of the method for forming the glass layer include the slot down-draw method, the fusion method, the float method, etc. The glass layer formed into a plate shape by these methods may be chemically polished with a solvent such as hydrofluoric acid as necessary to make it thinner or improve its smoothness.

[0135] (Hard coat layer) The hard coat layer constituting the optical element can be formed from any appropriate resin as long as it has sufficient surface hardness, excellent mechanical strength, and excellent light transmittance. Specific examples of the resin include thermosetting resins, thermoplastic resins, ultraviolet curable resins, etc.

[0136] Examples of the ultraviolet curable resin include polyester-based, acrylic-based, urethane-based, amide-based, silicone-based, and epoxy-based ultraviolet curable resins. The ultraviolet curable resin contains ultraviolet curable monomers, oligomers, and polymers. Preferred ultraviolet curable resins include resin compositions containing an acrylic monomer component or oligomer component having preferably 2 or more, more preferably 3 to 6 ultraviolet polymerizable functional groups. Typically, a photoinitiator is incorporated into the ultraviolet curable resin.

[0137] The hard coat layer can be formed by any appropriate method. For example, the hard coat layer can be formed by coating a resin composition for forming a hard coat layer on a substrate (including the resin layer and the glass layer), drying it, and irradiating the dried coating film with ultraviolet light to cure it. The thickness of the hard coat layer is not particularly limited, but is, for example, 2 to 20 μm, preferably 4 to 15 μm.

[0138] (Anti-reflection layer) As the antireflection 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 to 140 nm and a refractive index of 1.35 to 1.55, (ii) a laminate having a medium refractive index layer, a high refractive index layer, and a low refractive index layer in this order, and (iii) an alternating multilayer laminate of a high refractive index layer and a low refractive index layer can be mentioned.

[0139] Examples of materials that can form the 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 1.55. Examples of materials that can form the high refractive index layer include titanium oxide (TiO2), niobium oxide (Nb2O3 or Nb2O5), tin-doped indium oxide (ITO), etc. The refractive index of the high refractive index layer is typically about 1.60 to 2.20. Examples of materials that can form the medium refractive index layer include titanium oxide (TiO2) and a mixture of a material that can form a low refractive index layer and a material that can form a high refractive index layer (for example, a mixture of titanium oxide and silicon oxide). The refractive index of the medium refractive index layer is typically about 1.50 to 1.85. The thicknesses of the low refractive index layer, the medium refractive index layer, and the high refractive index layer can be set so as to achieve an appropriate optical film thickness according to the layer structure of the antireflection layer, the desired antireflection performance, etc.

[0140] The antireflection layer may be formed by a dry process (for example, sputtering), may be formed by a wet process (for example, coating), or may be formed by combining a dry process and a wet process. The thickness of the antireflection layer is not particularly limited, but is, for example, about 20 to 300 nm.

[0141] (Antiglare layer) As the antiglare layer constituting the optical element, known ones can be adopted without limitation, and generally, it is formed as a layer in which inorganic or organic particles are dispersed as an antiglare agent in a resin.

[0142] 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. When the particles and the thixotropy imparting agent aggregate, convex portions are formed on the surface of the anti-glare layer. With this configuration, the anti-glare layer has excellent display characteristics that achieve both anti-glare properties and prevention of white blooming. Moreover, despite forming the anti-glare layer by utilizing the aggregation of particles, it is possible to prevent the generation of protrusions on the surface of the anti-glare layer that would be an appearance defect and improve the product yield.

[0143] Examples of the resin include thermosetting resins and radiation curable resins that cure with ultraviolet rays or light. It is also possible to use commercially available thermosetting resins, ultraviolet curable resins, etc. as the resin. The particles for forming the anti-glare layer mainly function to impart anti-glare properties by making the surface of the formed anti-glare layer uneven and to control the haze value of the anti-glare layer. The haze value of the anti-glare layer can be designed by controlling the refractive index difference between the particles and the resin.

[0144] The weight average particle diameter (D) of the particles is preferably in the range of 2.5 to 10 μm. By setting the weight average particle diameter of the particles within the above range, for example, the anti-glare property can be more excellent and white blooming can be prevented. The weight average particle diameter of the particles is more preferably in the range of 3 to 7 μm. The weight average particle diameter of the particles can be measured, for example, by the Coulter counter method. For example, using a particle size distribution measuring device (trade name: Coulter Multisizer, manufactured by Beckman Coulter, Inc.) that utilizes the pore electrical resistance method, the electrical resistance of the electrolyte corresponding to the volume of the particles when the particles pass through the pores is measured to measure the number and volume of the particles, and the weight average particle diameter is calculated.

[0145] The shape of the particles is not particularly limited. For example, it may be a substantially spherical shape like beads, or an irregular shape such as powder, but a substantially spherical shape is preferred, more preferably, substantially spherical particles with an aspect ratio of 1.5 or less, and most preferably spherical particles.

[0146] The thickness (d) of the antiglare layer is not particularly limited, but it is preferably in the range of 3 to 12 μm. By setting the thickness (d) of the antiglare layer within the above range, for example, the occurrence of curl in the optical laminate can be prevented, and problems such as a decrease in productivity due to poor transportability can be avoided.

[0147] The manufacturing method of the antiglare layer is not particularly limited, and it may be manufactured by any method. For example, an antiglare layer forming material (coating liquid) containing the resin, the particles, the thixotropy imparting agent, and the solvent is prepared, the antiglare layer forming material (coating liquid) is coated to form a coating film, and the coating film is cured to form an antiglare layer, whereby it can be manufactured. A transfer method using a mold, a method of imparting an uneven shape by an appropriate method such as sandblasting or an embossing roll, etc. can also be used in combination. As a method of coating the antiglare layer forming material, for example, coating methods such as a fan coat method, a die coat method, a spin coat method, a spray coat method, a gravure coat method, a roll coat method, a bar coat method, etc. can be used.

[0148] The antiglare layer may have a multi-layer structure in which two or more layers are laminated. The above-described antireflection layer may be disposed on the antiglare layer. For example, light reflection at the air-antiglare layer interface is one of the factors that reduce the visibility of an OLED display device. The antireflection layer reduces surface reflection thereof. Note that the antiglare layer and the antireflection layer may each have a multi-layer structure in which two or more layers are laminated.

[0149] (Intermediate layer) The intermediate layer constituting the optical element is formed between the resin layer and the hard coat layer, the antireflection layer, or the antiglare layer. By forming this intermediate layer, the adhesion between the resin layer and the hard coat layer, the antireflection layer, or the antiglare layer is improved.

[0150] The mechanism for forming the intermediate layer (also referred to as the penetration layer or compatible layer) is not particularly limited. For example, in the formation of the hard coat layer, antireflection layer, or antiglare layer, it is formed during the process of applying, penetrating, and drying a coating liquid for forming the hard coat layer, a coating liquid for forming the antireflection layer, or a coating liquid for forming the antiglare layer on the resin layer. In the drying process, for example, a coating liquid for forming the hard coat layer, a coating liquid for forming the antireflection layer, or a coating liquid for forming the antiglare layer penetrates into the resin layer, and the intermediate layer containing the resin derived from the resin layer and the resin derived from the hard coat layer, antireflection layer, or antiglare layer is formed. The resin contained in the intermediate layer is not particularly limited. For example, it may be simply a mixture (compatible) of the resin contained in the resin layer and the resin contained in the hard coat layer, antireflection layer, or antiglare layer. Also, the resin contained in the intermediate layer may be such that at least one of the resin contained in the resin layer and the resin contained in the hard coat layer, antireflection layer, or antiglare layer has undergone a chemical change by heating, light irradiation, etc.

[0151] (Shock absorption layer) The shock absorption layer constituting the optical element can be composed of any suitable resin layer capable of achieving a desired shock absorption rate. The resin layer may be composed of a resin film or an adhesive. The shock absorption layer typically contains an epoxy resin, a urethane resin, or an acrylic resin. These resins may be used alone or in combination. The thickness of the shock absorption layer is not particularly limited, but is preferably 30 to 200 μm. If the thickness of the shock absorption layer is within such a range, an optical laminate having excellent impact resistance can be realized.

[0152] (Antistatic layer) 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. Specific coating methods include roll coating, bar coating, gravure coating, etc. The thickness of the antistatic layer is not particularly limited, but is preferably 1 to 1000 nm, more preferably 5 to 900 nm. The antistatic layer may be only one layer or two or more layers.

[0153] (Method for manufacturing an optical laminate) The method for manufacturing an optical laminate is not particularly limited. 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 absorption layer, etc. that constitute an optical element can be sequentially laminated on the viewing side of the OLED display panel for manufacturing. Alternatively, a laminate that constitutes the optical laminate can be prepared in advance and laminated on the viewing side of the OLED display panel for manufacturing. When preparing in advance a laminate that constitutes the optical laminate, it may be a laminate that constitutes the entire optical laminate, or a laminate that constitutes a part of the optical laminate may be divided and laminated on the viewing side of the OLED display panel. The layer or laminate that constitutes the optical element may be protected with a release liner or a surface protection film until use.

[0154] (Release liner) The adhesive layer may have a release liner provided on the surface (adhesive surface) of the adhesive layer until use. The release liner is used as a protective material for the adhesive layer and is peeled off when pasted onto an adherend. Note that the release liner does not constitute an optical element and does not necessarily have to be provided.

[0155] (Surface protection film) The outermost surface (the outermost surface on the viewing side) of the optical laminate may be protected by a surface protection film. The surface protection film may be one that is pasted by a consumer. Note that the surface protection film does not constitute an optical element and does not necessarily have to be provided. As the surface protection film, a known or commonly used surface protection film can be used, and it is not particularly limited. For example, a film having an adhesive layer on the surface of a plastic film can be used.

[0156] (The OLED display device of the present invention) An embodiment of an OLED display device in which an optical laminate is laminated on the viewing side of an OLED display panel will be described with reference to the drawings, but the present invention is not limited to this embodiment. FIG. 2 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.

[0157] As shown in FIG. 2, in the OLED display device 200, layers constituting the optical laminate 20 are laminated on the viewing side (the upper side in FIG. 2) of the OLED display panel 100. The OLED display panel 100 is not particularly limited, and for example, it may adopt the same configuration as the OLED display panel 100 described in FIG. 1.

[0158] In the OLED display device 200 of FIG. 2, 21 to 29 are layers constituting the optical laminate 20. 21 is an adhesive layer or an adhesive agent layer, 22 is a resin layer, a glass layer or a shock absorption layer, 23 is a hard coat layer or an antiglare layer, 24 is an adhesive layer or an adhesive agent layer, 25 is a resin layer, a glass layer or a shock absorption layer, 26 is an adhesive layer or an adhesive agent layer, 27 is a resin layer, a glass layer or a shock absorption layer, 28 is a hard coat layer or an antiglare layer, 29 is an antireflection layer. Any one of 21, 24, and 26 is an adhesive layer. The laminated structure of the optical laminate 20 shown in FIG. 2 is not limited to this embodiment, and other layers constituting an optical element may be inserted between any layers of the laminated structure of the optical laminate 20 shown in FIG. 2, and any layer of the laminated structure of the optical laminate 20 shown in FIG. 2 may not exist.

[0159] In FIGS. 3(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.

[0160] In FIG. 3(a), the pressure-sensitive adhesive film 300 with a substrate has a configuration in which a pressure-sensitive adhesive layer 31 and a substrate 32 are laminated in this order on the upper side of a release liner 33. The substrate 32 is not an essential component (see FIG. 3(b)), but it is preferably present from the viewpoint of improving impact resistance. The release liner 33 is temporarily attached to the surface of the pressure-sensitive adhesive layer 31. The release liner 33 is not particularly limited, but for example, a sheet-like substrate having a release layer formed by a release treatment agent on one side thereof so that the one side becomes a release surface can be preferably used. Before bonding to the OLED display panel 100 as the adherend, the release liner 33 is peeled off from the surface of the pressure-sensitive adhesive layer 31, and the exposed surface of the pressure-sensitive adhesive layer 31 is bonded to the surface of the OLED display panel 100, whereby the pressure-sensitive adhesive film is temporarily attached to the OLED display panel 100. The thickness of the release liner 33 is not particularly limited, but for example, it is 3 to 200 μm, preferably 10 to 100 μm.

[0161] The form in which the pressure-sensitive adhesive film is temporarily attached to the OLED display panel 100 obtained by the above operation is shown in FIG. 3(c). In FIG. 3(c), the pressure-sensitive adhesive layer 31 of the pressure-sensitive adhesive film is in contact with the viewing side (upper side) of the OLED display panel 100.

[0162] When the pressure-sensitive adhesive film 300 has a substrate 32, a pressure-sensitive adhesive film with the release liner 33 omitted can also be used. By winding the pressure-sensitive adhesive film 300, the adhesive surface of the pressure-sensitive adhesive layer 31 that does not face the substrate 32 may be in contact with and protected by the surface of the substrate 32 where the pressure-sensitive adhesive layer 31 does not exist (roll form). In the pressure-sensitive adhesive film having a roll form, before bonding to the OLED display panel 100, the surface of the pressure-sensitive adhesive layer 31 is exposed, and the exposed surface of the pressure-sensitive adhesive layer 31 is bonded to the surface of the OLED display panel 100, whereby the pressure-sensitive adhesive film is temporarily attached to the OLED display panel 100.

[0163] By performing an adhesive force increasing treatment on the pressure-sensitive adhesive layer 31 of the pressure-sensitive adhesive film temporarily attached to the adherend, the adhesive force of the pressure-sensitive adhesive layer 31 increases, and the adherend and the substrate 32 are fixed via the pressure-sensitive adhesive layer 31.

[0164] In this specification, "fixation" means that two laminated layers are firmly adhered, and it is a state where separation at the interface between the two is impossible or difficult. "Temporary adhesion" means that the adhesive force between two laminated layers is small, and it is a state where the two can be easily separated at the interface.

Example

[0165] Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited by these examples.

[0166] [Example 1: Preparation of Adhesive Film 1] ·Preparation of (meth)acrylic polymer 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 hydroxyethyl acrylate (HEA) was charged into a four-necked flask equipped with a stirrer, a thermometer, a nitrogen gas inlet tube, and a cooler. Further, 0.1 part by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator was charged together with ethyl acetate with respect to 100 parts by weight of the monomer mixture (solid content). After introducing nitrogen gas while gently stirring for nitrogen substitution, 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%, and a solution of a (meth)acrylic polymer having a weight average molecular weight of 2 million was prepared.

[0167] ·Preparation of Acrylic Adhesive Composition 1 Based on 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 dye compound (polymethine compound of the following formula (3)), 0.1 part by weight of an isocyanate-based crosslinking agent (trade name: Takenate D110N, trimethylolpropane xylylene diisocyanate, manufactured by Mitsui Chemicals, Inc.), 0.3 part by weight of benzoyl peroxide as a peroxide-based crosslinking agent (trade name: Niper BMT, 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 to prepare an acrylic pressure-sensitive adhesive composition 1.

[0168] [Chemical formula]

[0169] · Preparation of Adhesive Film 1 Acrylic pressure-sensitive adhesive composition 1 was uniformly coated on the surface of a 38-μm-thick polyethylene terephthalate film (PET film, transparent substrate, release liner) treated with a silicone-based release agent using a fountain coater, and dried in an air-circulating constant-temperature oven at 155°C for 2 minutes to form an adhesive layer with a thickness of 20 μm. Subsequently, the obtained adhesive layer was peeled off from the PET film to obtain Adhesive Film 1. Adhesive Film 1 corresponds to a "substrate-free adhesive film".

[0170] [Example 2: Preparation of Adhesive Film 2] · Preparation of Acrylic Pressure-Sensitive Adhesive Composition 2 An acrylic pressure-sensitive adhesive composition 2 was prepared in the same manner as in Example 1, except that the blending amount of the ultraviolet absorber was 1.3 parts by weight and the blending amount of the dye compound was 4.3 parts by weight based on 100 parts by weight of the solid content of the (meth)acrylic polymer solution.

[0171] · Preparation of Adhesive Film 2 The acrylic pressure-sensitive adhesive composition 2 was uniformly applied onto the surface of a 38-μm thick polyethylene terephthalate film (PET film, transparent base material, release liner) treated with a silicone-based release agent using a fountain coater, and dried in an air-circulating constant-temperature oven at 155°C for 2 minutes to form an adhesive layer with a thickness of 20 μm. Subsequently, after pasting it onto a transparent plastic film base material (acrylic film, manufactured by Toyo Steel Co., Ltd., trade name "HX40UF", thickness: 40 μm), the PET film was peeled off to produce an adhesive film 2. The adhesive film 2 corresponds to an "adhesive film with a base material".

[0172] [Example 3: Production of Adhesive Film 3] · Preparation of Acrylic Pressure-Sensitive Adhesive Composition 3 An acrylic pressure-sensitive adhesive composition 3 was prepared in the same manner as in Example 1, except that the blending amount of the ultraviolet absorber was 0.8 parts by weight and the blending amount of the dye compound was 2.3 parts by weight with respect to 100 parts by weight of the solid content of the (meth)acrylic polymer solution.

[0173] · Production of Adhesive Film 3 The acrylic pressure-sensitive adhesive composition 3 was uniformly applied onto the surface of a 38-μm thick polyethylene terephthalate film (PET film, transparent base material, release liner) treated with a silicone-based release agent using a fountain coater, and dried in an air-circulating constant-temperature oven at 155°C for 2 minutes to form an adhesive layer with a thickness of 40 μm. Subsequently, after pasting it onto a base material (trade name "RV20", thickness: 20 μm, manufactured by Toyo Steel Co., Ltd.), the PET film was peeled off to produce an adhesive film 3. The adhesive film 3 corresponds to an "adhesive film with a base material".

[0174] [Comparative Example 1: Production of Adhesive Film 4] An acrylic pressure-sensitive adhesive composition 4 was prepared in the same manner as in Example 1, except that no ultraviolet absorber was blended as the acrylic pressure-sensitive adhesive composition 1. Also, an adhesive film 4 was produced in the same manner as in Example 1, except that the acrylic pressure-sensitive adhesive composition 4 was used. The adhesive film 4 corresponds to a "base-material-free adhesive film".

[0175] [Comparative Example 2: Preparation of Adhesive Film 5] The acrylic-based pressure-sensitive adhesive composition 4 was uniformly applied onto the surface of a 38-μm thick polyethylene terephthalate film (PET film, transparent substrate, release liner) treated with a silicone-based release agent using a fountain coater, and dried in an air-circulating constant-temperature oven at 155°C for 2 minutes to form a 20-μm thick pressure-sensitive adhesive layer. Subsequently, after pasting it onto a transparent plastic film substrate (acrylic film, manufactured by Toyo Kohan Co., Ltd., trade name "HX40UF", thickness: 40 μm), the PET film was peeled off to prepare an adhesive film 5. The adhesive film 5 corresponds to an "adhesive film with substrate".

[0176] [Comparative Example 3: Preparation of Adhesive Film 6] The acrylic-based pressure-sensitive adhesive composition 4 was uniformly applied onto the surface of a 38-μm thick polyethylene terephthalate film (PET film, transparent substrate, release liner) treated with a silicone-based release agent using a fountain coater, and dried in an air-circulating constant-temperature oven at 155°C for 2 minutes to form a 40-μm thick pressure-sensitive adhesive layer. Subsequently, after pasting it onto a substrate (trade name "RV20", thickness 20 μm, manufactured by Toyo Kohan Co., Ltd.), the PET film was peeled off to prepare an adhesive film 6. The adhesive film 6 corresponds to an "adhesive film with substrate".

[0177] [Evaluation] The following evaluations were performed on the adhesive films 1 to 6 obtained in the examples and comparative examples.

[0178] [Measurement of Weight-Average Molecular Weight (Mw) of (Meth)Acrylic Polymer] The weight-average molecular weight (Mw) of the obtained (meth)acrylic polymer was measured by GPC (gel permeation chromatography). · Analytical instrument: HLC-8120GPC manufactured by Tosoh Corporation · Column: G7000HXL + GMHXL + GMHXL manufactured by Tosoh Corporation · Column size: Each 7.8 mmφ × 30 cm, total 90 cm · Column temperature: 40°C · Flow rate: 0.8 ml / min · Injection volume: 100 μl · Eluent: Tetrahydrofuran · Detector: Differential refractometer (RI) · Standard sample: Polystyrene

[0179] (Evaluation of water vapor transmission rate) The water vapor transmission rates of the pressure-sensitive adhesive films obtained in the examples and comparative examples were examined. Specifically, under the environment of a temperature of 40°C and a relative humidity of 92%, in accordance with JIS Z0208, the water vapor transmission rate (g / m 2 · 24 h) of the pressure-sensitive adhesive film was measured. The results are shown in Table 1.

[0180] (Measurement of light transmittance) The pressure-sensitive adhesive films obtained in the examples and comparative examples were bonded to a glass plate to prepare measurement samples. 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 also measured. The results are shown in Table 1.

[0181] (Measurement of the variation ratio of light transmittance before and after humidification) After exposing the pressure-sensitive adhesive films obtained in the examples and comparative examples to an environment of a temperature of 85°C and a relative humidity of 85% for 240 hours, the variation ratio of the light transmittance before and after humidification at a wavelength of 380 nm was calculated according to the following formula. Variation 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) The results are shown in "Variation ratio of light transmittance at a wavelength of 380 nm before and after 85°C 85% (after 240 h)" in Table 1.

[0182] Also, the variation ratio of the light transmittance was calculated by appropriately changing the humidification conditions or wavelengths as described in Table 1. The results are shown in Table 1.

[0183] (Measurement of loss factor (tanδ)) The pressure-sensitive adhesive films obtained in the examples and comparative examples were punched into a size of Φ8 mm using a jig and set on the probe of ARES-G2 (TA instruments). Measurements were taken at a frequency of 1 Hz with a strain of 0.05% at every 5 °C from -50 °C to 200 °C. The peak top value of the peak of the loss factor (tanδ) was extracted from the obtained data (Figure 4). The results are described in "Loss factor (tanδ)" in Table 1.

[0184] (Evaluation of impact force) The impact forces (N) of the pressure-sensitive adhesive films obtained in the examples and comparative examples were evaluated by a ball drop test. The results are described in Table 1.

[0185] · Preparation of evaluation samples Regarding the pressure-sensitive adhesive films described in the examples and comparative examples, a pressure-sensitive paper (manufactured by Fuji Film Co., Ltd., pressure measurement film Prescale, ultra-low pressure type) was attached to (1) one side of the adhesive layer or (2) the side opposite to the side where the base material was attached in the adhesive layer, and a sample laminated in the order of the base material, the adhesive layer, and the pressure-sensitive paper was obtained. The obtained sample was subjected to an autoclave (50 °C, 0.5 MPa, 15 minutes) to obtain an evaluation sample. For the above (1), it corresponds to the pressure-sensitive adhesive films 1 and 4 of Example 1 and Comparative Example 1, and for the above (2), it corresponds to the other examples and comparative examples and their pressure-sensitive adhesive films.

[0186] · Test method 1: The evaluation samples according to Examples 1 to 3 and Comparative Examples 1 to 3 are set on the stage of the ball drop impact tester (X in Figure 5) described below. In Figure 5, X1 is the base material, X2 is the adhesive layer, and X3 is the pressure-sensitive paper. In the evaluation samples according to Example 1 and Comparative Example 1, X1 does not exist. 2: A 10 g iron ball (X4 in Figure 5) is set at a height of 30 cm (X5 in Figure 5). 3: The iron ball is dropped, and the impact force is measured by a sensor under the stage, and the results are described in Table 1.

[0187]

Table 1

Description of Symbols

[0188] 100 OLED display panel 10R Red OLED layer 10G Green OLED layer 10B Blue OLED layer 11a Transparent electrode (cathode) 11b Back electrode (anode) 12R Red OLED element 12G Green OLED element 12B Blue OLED element 13 Substrate 14 TFT layer 15 Color filter 15R Red coloring layer 15G Green coloring layer 15B Blue coloring layer 16 Black matrix layer W External light G Reflected light C1 First optical path (direct light) C2 Second optical path (reflected light) 17 Bonding layer 200 OLED display device 20 Optical laminate 21 Adhesive layer or bonding agent layer 22 Resin layer, glass layer or shock absorption layer 23 Hard coat layer or anti-glare layer 24 Adhesive layer or bonding agent layer 25 Resin layer, glass layer or shock absorption layer 26 Adhesive layer or bonding agent layer 27 Resin layer, glass layer or shock absorption layer 28 Hard coat layer or anti-glare layer 29 Anti-reflection layer 300 Adhesive film with substrate 301 Adhesive film 302 OLED display device 31 Adhesive layer 32 Substrate (resin layer) 33 Release liner X Ball drop impact tester X1 Base material X2 Adhesive layer X3 Pressure-sensitive paper X4 Iron ball X5 Height of the iron ball

Claims

1. An adhesive film used in an OLED display device in which only an optical element with a polarization degree of 95% or less is laminated on the viewing side of the OLED element, As a layer constituting the optical element, it has at least one layer containing an ultraviolet absorber, It has an adhesive layer, The light transmittance at a wavelength of 380 nm is 20% or less, The ratio of the variation in the light transmittance at 380 nm, 450 nm, 550 nm, and 650 nm after exposure to an environment of 85°C and 85% relative humidity for 240 hours is 0.9 to 1.

2. An adhesive film for an OLED display device characterized by this.

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, further having a resin layer.

4. An OLED display device in which only an optical element with a polarization degree of 95% or less is laminated on the viewing side of the OLED element, including the adhesive film according to Claim 1 or 2.

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