CN120209729A

CN120209729A - Adhesive film for OLED display devices

Info

Publication number: CN120209729A
Application number: CN202411898462.XA
Authority: CN
Inventors: 三浦大生; 山本真也; 秋田雄贺; 永田拓也; 藤田昌邦
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2023-12-27
Filing date: 2024-12-23
Publication date: 2025-06-27
Also published as: JP2025103336A; KR20250101873A

Abstract

The present invention relates to an adhesive film for an OLED display device. The invention provides an adhesive film capable of imparting high weather resistance and impact resistance to an OLED display device without using a polarizing plate. An adhesive film for an OLED display device, which is used for an OLED display device in which only an optical element having a polarization degree of 95% or less is laminated on the visual recognition side of an OLED element, characterized in that the adhesive film for an OLED display device has at least one layer containing an ultraviolet absorber as a layer constituting the optical element, the adhesive film for an OLED display device has an adhesive layer having a peak of a loss factor (tan δ) at a region of 0 ℃ or less, the peak top value of the peak being 1.5 or more, and the light transmittance at a wavelength of 380nm of the adhesive film for an OLED display device is 20% or less.

Description

Adhesive film for OLED display device

Technical Field

The present invention relates to an adhesive film for an OLED display device. More particularly, the present invention relates to an adhesive film used in an OLED display device that does not use a polarizing plate.

Background

Compared with a liquid crystal display device, an OLED (organic light emitting diode) display device has advantages of high visual recognition, small viewing angle dependence, fast response speed, and the like. In addition, the OLED display device does not use a backlight, and thus is advantageous in terms of thickness reduction, and can be used as a foldable device that can be flexibly bent or bendable.

An OLED display device generally has an OLED element in which an anode, an OLED layer including a light emitting layer, and a cathode are sequentially stacked. Since a transparent conductive material having a high refractive index such as ITO or a metal material having a high reflectance is used for an electrode (anode or cathode) of the OLED element, external light is reflected by the electrode, and there is a problem in that contrast is lowered and reflection due to internal reflection is generated, and display performance of the OLED display device may be deteriorated. In order to suppress adverse effects caused by external light reflection, a circular polarizing plate such as a polarizing plate and a λ/4 plate is proposed on the visual recognition side of an OLED display device (for example, patent document 1). Such a circularly polarizing plate also has a function of blocking ultraviolet rays contained in external light and preventing degradation of the OLED element caused by the ultraviolet rays. In addition, the circular polarizing plate has a function of absorbing an impact from the outside and also preventing damage of the OLED display device according to the mechanical characteristics of the circular polarizing plate itself. However, when a circular polarizing plate is used, the light utilization efficiency (i.e., the lighting rate) is poor due to absorption by the polarizing plate, and the brightness becomes low. When the light emission intensity of the OLED element is increased in order to obtain a desired luminance, power consumption increases, and the lifetime of the OLED element is shortened. In addition, when the polarizing plate includes an adhesive layer for adhesion, the thickness may reach about 0.15mm, which is disadvantageous for the thinning of the OLED display device. Further, since the circular polarizing plate is expensive, there is a problem in that the manufacturing cost becomes high.

As an alternative to the circularly polarizing plate, there is proposed a method in which a color filter is disposed on the visual recognition side of an OLED element, and the color filter having a color similar to that of the light emission of an OLED layer is aligned so as to face the light emission layer of the OLED, thereby improving the light emission intensity of the OLED element while preventing reflection of external light (for example, patent document 2). As one form of the OLED display device, an OLED display device having a microcavity (also referred to as a multiple reflection interference, an optical resonator, or a microresonator) structure is known. According to the OLED display device having the microcavity structure, the spectrum of light extracted to the outside becomes steep and high in intensity, and therefore brightness and color purity can be improved (for example, patent document 3). In an OLED display device, 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 on the visual recognition side of an OLED element in order to impart functions such as surface protection and bendability.

Prior art literature

Patent literature

Patent document 1 Japanese patent laid-open publication No. 2003-332068

Patent document 2 Japanese patent application laid-open No. 2018-112715

Patent document 3 Japanese patent application laid-open No. 2015-207377

Disclosure of Invention

Problems to be solved by the invention

However, in the OLED display device not using such a polarizing plate, there is a problem in that the weatherability of the OLED element is low. The reason for this is that the ultraviolet absorption function of the color filter is insufficient as compared with the case of using a polarizing plate, and thus the OLED element is likely to deteriorate with time due to ultraviolet rays contained in external light.

Further, although the polarizing plate is excellent in impact resistance, it is possible to impart sufficient impact resistance to the OLED display device, there is a problem that the impact resistance of the OLED display device becomes insufficient without using the polarizing plate.

Accordingly, an object of the present invention is to provide an adhesive film capable of imparting high weather resistance and impact resistance to an OLED display device not using a polarizing plate.

Means for solving the problems

The present inventors have made intensive studies to achieve the above object, and as a result, have found that if an OLED display device having a specific structure is used as an adhesive film for an OLED display device, sufficient weather resistance and impact resistance can be exhibited even when the OLED display device is not used as a polarizing plate, and have completed the present invention.

Specifically, the present invention provides an adhesive film for an OLED display device, which is used for an OLED display device in which only an optical element having a polarization degree of 95% or less is laminated on the visual recognition side of the OLED element, and which has at least one layer containing an ultraviolet absorber as a layer constituting the optical element, and which has an adhesive layer having a peak of a loss factor (tan δ) in a region of 0 ℃ or less, the peak having a peak top value of 1.5 or more, and the light transmittance at a wavelength of 380nm of the adhesive film for an OLED display device being 20% or less.

The adhesive layer preferably contains an ultraviolet absorber.

The adhesive film preferably further has a resin layer.

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

Effects of the invention

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

Drawings

Fig. 1 is a schematic cross-sectional view showing an embodiment of an OLED display panel for an OLED display device of the present invention.

Fig. 2 is a schematic cross-sectional view showing an embodiment of the OLED display device of the present invention.

Fig. 3 (a) and 3 (b) are schematic cross-sectional views showing one embodiment of the adhesive film of the present invention. (c) To show a schematic cross-sectional view of one embodiment of an OLED display device using the adhesive film of the present invention.

Fig. 4 is a graph showing loss factor (tan δ) of an adhesive layer in an adhesive film according to an embodiment of the present application.

Fig. 5 is a schematic view of an apparatus for ball drop test according to an embodiment of the present application.

Description of the reference numerals

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 light path (direct light)

C2 second light path (reflected light)

17 Bonding layer

200 OLED display device

20 Optical laminate

21 Adhesive layer or adhesive layer

22 Resin layer, glass layer or impact absorbing layer

23 Hard coat or antiglare layer

24 Adhesive layer or adhesive layer

25 Resin layer, glass layer or impact absorbing layer

26 Adhesive layer or adhesive layer

27 Resin layer, glass layer or impact absorbing layer

28 Hard coat or antiglare layer

29 Antireflection layer

300 Adhesive film with substrate

301 Adhesive film

302 OLED display device

31 Adhesive layer

32 Base material (resin layer)

33 Release liner

X ball drop impact testing machine

X1 substrate

X2 adhesive layer

X3 pressure sensitive paper

X4 iron ball

Height of X5 iron ball

Detailed Description

The invention provides an adhesive film for an OLED display device. The adhesive film for an OLED display device of the present invention is sometimes referred to as "adhesive film of the present invention". In addition, the present invention provides an OLED display device having an optical laminate including the adhesive film described above. The optical laminate is a laminate obtained by removing an 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 an optical element.

In the OLED display device of the present invention, only an optical element having a polarization degree of 95% or less is laminated on the visual recognition side of the OLED element in the OLED display panel. The phrase "an optical element having a polarization degree of 95% or less is laminated on the viewing side of an OLED element" means that an optical element having a polarization degree of more than 95% is not included in the optical element on the viewing side of the OLED element. The "optical element having a polarization degree of more than 95%" is not particularly limited, and includes polarizing plates such as linear polarizing plates, 1/4 phase difference plates, 1/2 phase difference plates, circular polarizing plates, and reflective polarizing plates. That is, the OLED display device of the present invention may be described as an OLED display device that does not include a polarizing plate on the visual recognition side of the OLED element. The polarization degree is a value obtained by the following formula based on the parallel transmittance Tp and the orthogonal transmittance Tc measured by an ultraviolet-visible spectrophotometer and subjected to visibility correction.

Degree of polarization (%) = { (Tp-Tc)/(tp+tc) } ^1/2 ×100

The OLED display device of the present invention does not include the polarizing plate on the visual recognition side of the OLED element, and can suppress absorption of light emitted from the OLED element by the polarizing plate, improve the lighting rate, save power consumption, and contribute to a longer life of the OLED element. In addition, by not using a polarizing plate, the thickness can be reduced, and the manufacturing cost can be reduced.

The adhesive film of the present invention is characterized by comprising at least one layer containing an ultraviolet absorber as a layer constituting an optical element in an OLED display device, and by comprising an adhesive layer having a peak of tan delta at a region of 0 ℃ or less, the peak having a peak top value of 1.5 or more and a light transmittance at a wavelength of 380nm of 20% or less. The adhesive film of the present invention has the above-described characteristics and is suitable in improving weather resistance and impact resistance in an OLED display device.

The adhesive film of the present invention comprises at least an adhesive layer. The adhesive layer may be a layer containing an ultraviolet absorber. The adhesive film of the present invention may have a resin layer in addition to the adhesive layer, and the resin layer may be a layer containing an ultraviolet absorber. In the case where the adhesive film of the present invention has a resin layer, it is preferable from the viewpoint of improving impact resistance. The adhesive film of the present invention may have a structure in which an optical element other than the adhesive layer and the resin layer to be laminated to the OLED display device of the present invention is used as the adhesive film. In the adhesive film of the present invention, at least one of the adhesive layers may be a high refractive index adhesive layer, or may be all high refractive index adhesive layers.

The moisture permeability of the pressure-sensitive adhesive film of the present invention is not particularly limited, and is preferably 5000g/m ².24 hours or less, more preferably 3500g/m ².24 hours or less, more preferably 2000g/m ².24 hours or less, more preferably 1000g/m ².24 hours or less, more preferably 500g/m ².24 hours or less, more preferably 200g/m ².24 hours or less, more preferably 100g/m ².24 hours or less, and particularly preferably 80g/m ².24 hours or less. The lower limit of the moisture permeability is not particularly limited, but is 10g/m ².24 hours from the viewpoint of suppressing humidification expansion. The adhesive film of the present invention has a moisture permeability in the above range, and tends to suppress deterioration of the panel due to moisture. The moisture permeability of the adhesive film of the present invention can be measured in an environment having a temperature of 40 ℃ and a relative humidity of 92% according to JIS Z0208, and can be adjusted by the type, thickness, etc. of the resin constituting the adhesive film of the present invention.

The light transmittance of the adhesive film of the present invention at a wavelength of 380nm 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, more preferably 2% or less, and particularly preferably 1% or less. The lower limit of the light transmittance at the wavelength of 380nm is 0%. The method for measuring the light transmittance at a wavelength of 380nm is not particularly limited, and may be measured by using a spectrophotometer U4100 (manufactured by hitachi high technology corporation), for example. The light transmittance at wavelengths other than 380nm can be similarly measured by the above-described device.

The light transmittance of the pressure-sensitive adhesive film of the present invention at a wavelength of 450nm is not particularly limited, and is, for example, preferably 20% or less, more preferably 15% or less, still more preferably 10% or less, still 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 the wavelength of 450nm is 0%.

The transmittance change ratio at 380nm (hereinafter, sometimes referred to as "transmittance change ratio at 380nm after humidification") of the pressure-sensitive adhesive film of the present invention after exposure to an environment having a temperature of 85 ℃ and a relative humidity of 85% for 240 hours is not particularly limited as long as it is 0.9 to 1.2, preferably 0.95 to 1.2, more preferably 1 to 1.19, and even more preferably 1.07 to 1.19. By the fluctuation ratio of the light transmittance being within the above range, deterioration of the ultraviolet OLED element due to the external light with time can be prevented for a long period of time even in the presence of high temperature and high humidity.

The transmittance change ratio at 380nm after humidification can be calculated from the following equation.

Fluctuation ratio of transmittance at 380nm after humidification = (transmittance at 380nm after humidification)/(transmittance at 380nm at the initial wavelength)

In the adhesive film of the present invention, the method of adjusting the transmittance at a specific wavelength (for example, 380nm or the like) and the variation ratio of the transmittance is not particularly limited, and may be adjusted by, for example, the constitution of the layers constituting the optical element, specifically, the kind of the adhesive, the monomer composition, the degree of crosslinking, and the thickness of the adhesive constituting the adhesive layer. In particular, the acrylic pressure-sensitive adhesive composition described later can be used as a pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer, or can be adjusted by containing an ultraviolet absorber.

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

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

In the present specification, "adhesive film" includes the meaning of "adhesive sheet" and "adhesive tape". That is, the pressure-sensitive adhesive film of the present invention may be a pressure-sensitive adhesive sheet or 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 contain the adhesive layer having the high refractive index.

The adhesive film of the present invention may be a so-called "substrate-less" adhesive film having no substrate (corresponding to a "resin layer" described later), or may be a substrate-containing adhesive film. In the present specification, the "substrate-less" adhesive film may be referred to as "substrate-less adhesive film", and the type of adhesive film having a substrate may be referred to as "substrate-attached adhesive film". Examples of the substrate-free adhesive film include a double-sided adhesive sheet including only an adhesive layer. The pressure-sensitive adhesive layer in the double-sided pressure-sensitive adhesive sheet may be formed of one layer or may have a multilayer structure of two or more layers. Examples of the pressure-sensitive adhesive film with a base material include a single-sided pressure-sensitive adhesive film having a pressure-sensitive adhesive layer on one side of a base material and a double-sided pressure-sensitive adhesive film having a pressure-sensitive adhesive layer on both sides of a base material. The pressure-sensitive adhesive layer in the single-sided pressure-sensitive adhesive film may be formed of one layer or may have a multilayer structure of two or more layers. In addition, the two adhesive layers may be formed continuously or may be formed independently (i.e., with other layers interposed therebetween). One adhesive layer of the double-sided adhesive film may be formed of one layer, or may have a multilayer structure of two or more layers. In addition, the two adhesive layers may be formed continuously or may be formed independently (i.e., with other layers interposed therebetween). The other adhesive layer may be formed of one layer or may have a multilayer structure of two or more layers. In addition, the two adhesive layers may be formed continuously or may be formed independently (i.e., with other layers interposed therebetween). The "substrate" mentioned above means a support, and is a portion to be adhered to an adherend together with an adhesive layer when the adhesive film of the present invention is used (adhered) to the adherend. The release liner that is peeled off when the adhesive film is used (attached) is not contained in the above-described base material.

Hereinafter, each structure of the adhesive film of the present invention will be described.

(OLED display Panel)

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

Hereinafter, an embodiment of an OLED display panel constituting an 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 one embodiment of an OLED display panel.

As shown in fig. 1, the OLED display panel 100 has a red OLED element 12R in which a transparent electrode 11a, a red OLED layer 10R that emits red light, and a back electrode 11B are sequentially stacked, a green OLED element 12G in which a transparent electrode 11a, a green OLED layer 10G that emits green light, and a back electrode 11B are sequentially stacked, and a blue OLED element 12B in which a transparent electrode 11a, a blue OLED layer 10B that emits blue light, and a back electrode 11B are sequentially stacked. OLED elements 12R, 12G, 12B of each of the multiple colors are sequentially disposed on a substrate 13. A TFT (thin film transistor) layer 14 is formed on the surface of the substrate 13 on which each OLED element is disposed, and is connected to the back electrode 11B of each of the OLED elements 12R, 12G, 12B of the plurality of colors.

In the OLED display panel 100 of fig. 1, the color filters 15 are arranged on the visual recognition side (upper side in fig. 1) of the OLED elements 12R, 12G, 12B of each of the plurality of colors. The color filter 15 includes a red color layer 15R, a green color layer 15G, and a blue color layer 15B, and a black matrix layer 16 is provided between the color layers.

In fig. 1, the color filters 15 are arranged so that the red color layer 15R, the green color layer 15G, and the blue color layer 15B face the red OLED element 12R, the green OLED element 12G, and the blue OLED element 12B, respectively.

The transparent electrode 11a is either a cathode or an anode, but is generally provided as a cathode. As a material for forming the transparent electrode 11a, a transparent conductive material such as ITO (indium tin oxide), indium oxide, IZO (indium zinc oxide), snO ₂, znO, or the like is used.

The back electrode 11b functions as a counter electrode to the transparent electrode 11 a. The back electrode 11b is either an anode or a cathode, but is usually 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.

A bonding layer 17 is provided between the substrate 13 and the color filter 15. The bonding layer 17 has light transmittance. As a material of the bonding layer 17, a material used for a general OLED display device may be used, and for example, a photo-curable resin such as a photosensitive polyimide resin, a thermosetting resin, or the like may be used.

The OLED display panel 100 may have a structure of the OLED display panel, for example, a hole injection layer, a hole transport layer, an electron transport layer, a sealing layer, a touch sensor panel, or the like (not shown), in addition to the structure shown in fig. 1.

The OLED display panel of fig. 1 is characterized in that the color filters 15 are disposed on the OLED elements 12R, 12G, 12B of the respective multiple colors so as to face the color layers 15R, 15G, 15B of the same color, respectively. As shown in fig. 1, the white external light W passes through, for example, the red coloring layer 15R, further passes through the transparent electrode 11a and the red OLED layer 10R that emits red light and is reflected at the back electrode 11b, passes through the red OLED layer 10R, the transparent electrode 11a and the red coloring layer 15R again, and then the reflected light G enters the eyes of the observer.

The external light W is absorbed in green and blue by the red coloring layer 15R, and thus the light intensity becomes 1/3. In addition, the reflected light G passes through the red coloring layer 15R and the red OLED layer 10R again, thereby generating attenuation. In addition, the reflected light G is red, and thus red light emitted from the OLED layer 10R can be enhanced. In the same manner, when the external light W is incident on the green color layer 15G and the blue color layer 15B, the green light and the blue light can be enhanced, respectively. Therefore, by using a color filter in combination with the OLED display panel, reflection of external light can be greatly suppressed and the light intensity of the light emitted from the OLED element can be improved even when reflection is prevented without using a polarizing plate.

However, color filters are generally prone to interference irregularities caused by regular two-dimensional structures. In addition, the color filter has a problem that reflection is likely to occur at the interface, and the light collection rate of light emitted from the OLED element is reduced. In addition, in the color filter, there is a problem that the ultraviolet absorption function is insufficient as compared with the case of using a polarizing plate, and the ultraviolet OLED element included in the external light is easily deteriorated with time (i.e., the weather resistance is low). In addition, the color filter has a problem that the impact absorbing function is insufficient as compared with the case of using a polarizing plate.

In addition, the OLED display panel 100 of the present embodiment has a microcavity structure. Light generated from the OLED layers 10R, 10G, and 10B is emitted to the outside through the transparent electrode 11 a. Here, the emitted light includes two components, that is, "direct light" emitted directly from the OLED layers 10R, 10G, 10B toward the transparent electrode 11a, and "reflected light" emitted from the OLED layers 10R, 10G, 10B toward the rear electrode 11B and reflected at the rear electrode 11B toward the transparent electrode 11 a. That is, a first optical path C1 is formed in which a part of the light emitted from the OLED layers 10R, 10G, and 10B does not travel toward the rear surface electrode 11B, but travels toward the transparent electrode 11a and is emitted to the outside through the transparent electrode 11a, and a second optical path C2 is formed in which a remaining part of the light emitted from the OLED layers 10R, 10G, and 10B travels toward the rear surface electrode 11B, is reflected by the rear surface electrode 11B, and is emitted to the outside through the OLED layers 10R, 10G, and 10B and the transparent electrode 11 a. The OLED layers 10R, 10G, and 10B have different thicknesses so that the light components corresponding to the respective colors are enhanced by the interference of the direct light and the reflected light. That is, the thicknesses of the OLED layers 10R, 10G, and 10B are made different so that the optical path length between the back electrode (positive electrode) 11B and the transparent electrode (negative electrode) 11a matches the peak wavelength of the EL spectrum of each of red, green, and blue, and the strongest light is extracted 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 light generated in the OLED layer is repeatedly reflected between the positive electrode and the negative electrode, only light having a wavelength with a uniform optical path length resonates, and light having other wavelengths with an optical path length deviated is weakened, whereby the spectrum of light extracted to the outside becomes steep and high in intensity, and brightness and color purity are improved.

According to the OLED display panel having the microcavity structure, excellent effects of improving brightness and color purity can be obtained, and on the other hand, since the spectrum is steep, there is a possibility that a problem of strong viewing angle dependence (narrow viewing angle) occurs. Therefore, when an image is viewed from an oblique direction during image display, there is a case where a color shift of a color which looks different from the color which is intended to be displayed is generated.

(Optical element)

The optical element is an optical element laminated on the visual recognition side of the OLED display device, and includes at least an adhesive layer. The 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 (compatible layer), an impact absorbing layer, an antistatic layer, and the like. However, the optical element does not include an optical element having a degree of polarization of more than 95%, such as a polarizing plate.

(Adhesive layer)

The pressure-sensitive adhesive layer is a layer that has tackiness at normal temperature and adheres to an adherend with light pressure, and is a layer that maintains practical adhesive strength even when the adherend adhered to the pressure-sensitive adhesive layer is peeled off.

The adhesive layer constituting the optical element is preferably high in refractive index from the viewpoints of preventing interface reflection and improving the light collection efficiency of light emitted from the OLED element. The refractive index of the pressure-sensitive adhesive layer is preferably 1.57 or more, more preferably 1.575 or more, further preferably 1.580 or more, particularly preferably 1.585 or more, still more preferably 1.590 or more, and may be 1.595 or more.

The refractive index of the pressure-sensitive adhesive layer can be adjusted by, for example, the type and content of an aromatic ring-containing monomer, a high refractive index organic material, and a high refractive index inorganic material, which will be described later.

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

In the case where the OLED display device includes a color filter on the visual recognition side, 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, from the viewpoint of reducing color shift and interference unevenness of the OLED display device and suppressing image blur of the OLED display device due to light scattering, that is, the adhesive layer is in direct contact with the color filter.

The distance between the pressure-sensitive adhesive layer and the color filter means the distance (μm) between the surface of the pressure-sensitive adhesive layer in the direction of the color filter and the surface of the pressure-sensitive adhesive layer in the direction of the color filter, and corresponds to the thickness (μm) of another layer (total of two or more layers) when the other layer is laminated between the pressure-sensitive adhesive layer and the color filter.

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

The total light transmittance of the adhesive layer is not particularly limited, but is preferably 60% or more, more preferably 70% or more, still more preferably 80% or more, and particularly preferably 90% or more from the viewpoint of securing the luminance of the OLED display device. The upper limit of the total light transmittance of the adhesive layer is not particularly limited, and may be less than 100%, or 99.9% or less or 99% or less.

The haze value and total light transmittance of the pressure-sensitive adhesive layer can be measured by the methods specified in JIS7136 and JIS7361, respectively, and can be controlled by the type and thickness of the pressure-sensitive adhesive layer, the type and amount of light scattering particles to be described later, and the like.

The adhesive layer has a peak of loss factor (tan delta) at a region of 0 ℃ or less, and the peak top value of the peak is 1.5 or more. The loss factor is more preferably 1.8 or more, still more preferably 2.0 or more, and particularly preferably 2.2 or more. The maximum value of the loss factor is not particularly limited, and is preferably 5.0, more preferably 3.0, for example. When the adhesive layer includes two or more continuous adhesive layers having a multilayer structure, the loss factor (tan δ) of the adhesive layer is measured by considering the two or more adhesive layers as one adhesive layer. The loss factor of the pressure-sensitive adhesive layer in the above range tends to improve impact resistance.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is preferably 10 μm to 500 μm, more preferably 15 μm to 300 μm, still more preferably 15 μm to 200 μm, still more preferably 20 μm to 100 μm, and particularly preferably 20 μm to 40 μm from the viewpoint of improving impact resistance. In the case where the adhesive layer includes two or more adhesive layers, the thickness of the adhesive layer is the total thickness of the two or more adhesive layers.

The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is not particularly limited, and examples thereof include acrylic pressure-sensitive adhesives, rubber pressure-sensitive adhesives, vinyl alkyl ether pressure-sensitive adhesives, silicone pressure-sensitive adhesives, polyester pressure-sensitive adhesives, polyamide pressure-sensitive adhesives, urethane pressure-sensitive adhesives, fluorine-containing pressure-sensitive adhesives, and epoxy pressure-sensitive adhesives. Among them, an acrylic adhesive is preferable as an adhesive constituting the adhesive layer from the viewpoints of transparency, adhesiveness, weather resistance, cost, and ease of designing the adhesive. That is, the adhesive layer is preferably an acrylic adhesive layer composed of an acrylic adhesive. The above binders may be used singly or in combination of two or more.

The acrylic 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 a 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 polymer may be used alone or in combination of two or more.

The adhesive composition forming the adhesive layer may be in any form. For example, the adhesive composition may be of emulsion type, solvent type (solution type), active energy ray-curable type, hot melt type (hot melt type), or the like. Among them, solvent-based and active energy ray-curable adhesive compositions are preferred in terms of productivity and ease of obtaining an adhesive layer excellent in optical characteristics and appearance characteristics. 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 of a solvent-based or active energy ray-curable acrylic pressure-sensitive adhesive composition.

Examples of the pressure-sensitive adhesive composition (acrylic pressure-sensitive adhesive composition) for forming the acrylic pressure-sensitive adhesive layer include an acrylic pressure-sensitive adhesive composition containing an acrylic polymer as an indispensable component, and an acrylic pressure-sensitive adhesive composition containing a mixture of monomers (monomers) constituting the acrylic polymer (sometimes referred to as "monomer mixture") or a partial polymer thereof as an indispensable component. The former includes, for example, a so-called solvent-based acrylic pressure-sensitive adhesive composition. The latter may be, for example, a so-called active energy ray-curable acrylic pressure-sensitive adhesive composition. The "monomer mixture" mentioned above means a mixture containing monomer components constituting a polymer. The term "partial polymer" is sometimes referred to as "prepolymer" and refers to a composition obtained by partially polymerizing one or more monomer components in the monomer mixture.

The acrylic polymer is a polymer composed (formed) of an acrylic monomer as an indispensable monomer component (monomer component). The acrylic polymer is preferably a polymer composed (formed) of an alkyl (meth) acrylate as an indispensable monomer component. That is, the acrylic polymer preferably contains an alkyl (meth) acrylate as a structural unit. In the present specification, "(meth) acrylic" means "acrylic" and/or "methacrylic" ("acrylic" and "methacrylic" either or both), and the other are the same. The acrylic polymer is composed of one or two or more monomer components.

The alkyl (meth) acrylate as an essential monomer component is preferably an alkyl (meth) acrylate having a linear or branched alkyl group. The alkyl (meth) acrylate may be used alone or in combination of two or more.

Examples of the alkyl (meth) acrylate having a linear or branched alkyl group include, but are not limited to, alkyl (meth) acrylates having a linear or branched alkyl group 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, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. Among these, the alkyl (meth) acrylate having a linear or branched alkyl group is preferably an alkyl (meth) acrylate having a linear or branched alkyl group having 4 to 18 carbon atoms, and more preferably butyl acrylate. The above alkyl (meth) acrylate having a linear or branched alkyl group may be used singly or in combination of two or more.

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

The acrylic polymer may contain a copolymerizable monomer together with the alkyl (meth) acrylate as a monomer component constituting the polymer. That is, the acrylic polymer may contain a copolymerizable monomer as a structural unit. It should be noted that two or more copolymerizable monomers may be used singly or in combination.

The copolymerizable monomer is not particularly limited, and a monomer having an aromatic ring in a molecule thereof can be used to obtain an adhesive layer having a high refractive index, and can suppress the interface reflection with the OLED display panel and improve the light collection efficiency of light emitted from the OLED element. The monomer having an aromatic ring in the molecule is a monomer (monomer) having at least one aromatic ring in the molecule (one molecule). In the present specification, the "monomer having an aromatic ring in a molecule" is sometimes referred to as "aromatic ring-containing monomer".

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 or a combination of two or more of the above compounds may be used alone. Examples of the ethylenically unsaturated group include (meth) acryl, vinyl, and (meth) allyl. The (meth) acryl group is preferable from the viewpoint of polymerization reactivity, and the acryl group is more preferable from the viewpoints of flexibility and adhesion. From the viewpoint of suppressing the decrease in flexibility of the adhesive, it is preferable to use a compound having 1 number of ethylenically unsaturated groups contained in one molecule (i.e., a monofunctional monomer) as the aromatic ring-containing monomer.

The copolymerizable monomer is not particularly limited, and 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 and monomers having a hydroxyl group in the molecule are preferable.

The monomer having a nitrogen atom in the molecule is a monomer (monomer body) having at least one nitrogen atom in the molecule (one molecule). In this specification, the "monomer having a nitrogen atom in the molecule" is sometimes referred to as "nitrogen atom-containing monomer". The nitrogen atom-containing monomer is not particularly limited, and examples thereof include cyclic nitrogen-containing monomers, (meth) acrylamides, and the like. The monomer containing nitrogen atom may be used alone or in combination of two or more.

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 an N-vinyl cyclic amide (lactam-based vinyl monomer) and a vinyl monomer having a nitrogen-containing heterocycle.

The monomer having a hydroxyl group in the molecule is a monomer having at least one hydroxyl group (hydroxyl group) in the molecule (one molecule), and examples thereof include a monomer having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and having a hydroxyl group. However, the monomer having a hydroxyl group in the molecule does not contain the nitrogen atom-containing monomer. That is, in the present specification, a monomer having both a nitrogen atom and a hydroxyl group in the molecule is contained in the "nitrogen atom-containing monomer". In the present specification, the "monomer having a hydroxyl group in a molecule" described above is sometimes referred to as a "hydroxyl group-containing monomer". The hydroxyl group-containing monomers may be used singly or in combination of two or more.

Examples of the hydroxyl group-containing monomer include hydroxyl group-containing (meth) acrylates 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) acrylate, and more preferably 2-hydroxyethyl acrylate (HEA) or 4-hydroxybutyl acrylate (4 HBA).

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

Examples of copolymerizable monomers other than the nitrogen atom-containing monomer and the hydroxyl group-containing monomer include alicyclic structure-containing monomers, polyfunctional monomers, alkoxyalkyl (meth) acrylates, carboxyl group-containing monomers, epoxy group-containing monomers, and the like. Examples of the carboxyl group-containing monomer include acid anhydride group-containing monomers such as (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, and maleic anhydride and itaconic anhydride.

When the acrylic polymer contains the carboxyl group-containing monomer as a monomer component constituting the polymer, the proportion of the carboxyl group-containing monomer in the total monomer components (100 wt%) constituting the acrylic polymer is not particularly limited, but is preferably 0.1 wt% to 30 wt%, more preferably 0.5 wt% to 20 wt%.

The content of the base polymer (particularly, acrylic polymer) in the adhesive layer is not particularly limited, but is preferably 50 wt% or more (for example, 50 wt% to 100 wt%), more preferably 80 wt% or more (for example, 80 wt% to 100 wt%), and further preferably 90 wt% or more (for example, 90 wt% to 100 wt%) with respect to the total weight of the adhesive layer.

The base polymer such as the acrylic polymer contained in the pressure-sensitive adhesive layer is obtained by polymerizing a monomer component. The polymerization method is not particularly limited, and examples thereof include a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, a polymerization method using irradiation of active energy rays (active energy ray polymerization method), and the like.

In the polymerization of the monomer components, a polymerization initiator such as a solvent, a thermal polymerization initiator, a photopolymerization initiator (photoinitiator) or the like may be used depending on the kind of polymerization reaction. The polymerization initiator may be used alone or in combination of two or more.

The thermal polymerization initiator is not particularly limited, and examples thereof include azo-based polymerization initiators, peroxide-based polymerization initiators (e.g., dibenzoyl peroxide, t-butyl peroxymaleate, etc.), and redox-based polymerization initiators. Among them, the azo-based polymerization initiator disclosed in Japanese patent application laid-open No. 2002-69411 is preferable. Examples of the azo polymerization initiator include 2,2 '-azobisisobutyronitrile, 2' -azobis (2-methylbutyronitrile), dimethyl 2,2 '-azobis (2-methylpropionate), and 4,4' -azobis (-4-cyanovaleric acid). The thermal polymerization initiator may be used alone or in combination of two or more.

In the case where the azo-based polymerization initiator is used in the polymerization of the acrylic polymer, the amount of the azo-based polymerization initiator to be used is not particularly limited, and is preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, and further preferably 0.5 parts by weight or less, more preferably 0.3 parts by weight or less, based on 100 parts by weight of the total monomer components constituting the acrylic polymer.

The photopolymerization initiator is not particularly limited, and examples thereof include benzoin ether photopolymerization initiators, acetophenone photopolymerization initiators, α -ketol photopolymerization initiators, and aromatic sulfonyl chloride photopolymerization initiators. The photopolymerization initiator may be used singly or in combination of two or more.

In the case where the photopolymerization initiator is used in the polymerization of the acrylic polymer, the amount of the photopolymerization initiator to be used is not particularly limited, but is preferably 0.01 parts by weight or more, more preferably 0.1 parts by weight or more, and is preferably 3 parts by weight or less, more preferably 1.5 parts by weight or less, based on 100 parts by weight of the total monomer components constituting the acrylic polymer.

The adhesive layer may contain ultraviolet light absorber (UVA). When the adhesive layer contains an ultraviolet absorber, 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. In addition, deterioration of the high refractive index component due to ultraviolet rays can be suppressed, and a high light collection rate can be maintained. The ultraviolet absorber may be used alone or in combination of two or more.

The ultraviolet absorber is not particularly limited, and examples thereof include benzotriazole-based ultraviolet absorbers, hydroxyphenyl triazine-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, and hydroxybenzophenone-based ultraviolet absorbers. The ultraviolet absorber is preferably at least one ultraviolet absorber selected from benzotriazole-based ultraviolet absorbers, hydroxyphenyl triazine-based ultraviolet absorbers and benzophenone-based ultraviolet absorbers from the viewpoint of having high ultraviolet absorbability, obtaining an adhesive layer having excellent optical characteristics and high transparency, and having excellent light stability.

Examples of the benzotriazole ultraviolet absorber (benzotriazole compound) include 2- (2-hydroxy-5-t-butylphenyl) -2H-benzotriazole, an ester compound of phenylpropionic acid and 3- (2H-benzotriazol-2-yl) -5- (1, 1-dimethylethyl) -4-hydroxy (C _7-9 side chain and linear alkyl), and 2- (2H-benzotriazol-2-yl) -4, 6-bis (1-methyl-1-phenylethyl) phenol.

Examples of the hydroxyphenyl triazine ultraviolet light absorber (hydroxyphenyl triazine compound) include a reaction product of 2- (4, 6-bis (2, 4-dimethylphenyl) -1,3, 5-triazin-2-yl) -5-hydroxyphenyl and [ (C _10-16 (mainly C _12-13) alkoxy) methyl ] oxirane, 2- [4, 6-bis (2, 4-dimethylphenyl) -1,3, 5-triazin-2-yl ] -5- [3- (dodecyloxy) -2-hydroxypropoxy ] phenol), and 2, 4-bis- [ {4- (4-ethylhexyl oxy) -4-hydroxy } -phenyl ] -6- (4-methoxyphenyl) -1,3, 5-triazine.

Examples of the benzophenone-based ultraviolet absorber (benzophenone-based compound) and the hydroxybenzophenone-based ultraviolet absorber (hydroxybenzophenone-based compound) include 2, 4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (acid anhydride and trihydrate), 2-hydroxy-4-octoxybenzophenone, and 4-dodecyloxy-2-hydroxybenzophenone.

When the pressure-sensitive adhesive layer contains an ultraviolet absorber, the content of the ultraviolet absorber in the pressure-sensitive adhesive layer (particularly, the acrylic pressure-sensitive adhesive layer) is not particularly limited, but is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight or more, and even more preferably 0.1 parts by weight or more, based on 100 parts by weight of the base polymer (for example, acrylic polymer), from the viewpoint of suppressing deterioration of the OLED element due to ultraviolet rays contained in external light and obtaining an OLED display device excellent in weather resistance without using a polarizing plate. In addition, from the viewpoint of suppressing occurrence of yellowing phenomenon of the adhesive agent accompanied by addition of the ultraviolet absorber, and obtaining excellent optical characteristics, high transparency, and excellent appearance characteristics, the upper limit of the content of the ultraviolet absorber is preferably 20 parts by weight or less, more preferably 10 parts by weight or less, and further preferably 8 parts by weight or less, relative to 100 parts by weight of the acrylic polymer.

The pressure-sensitive adhesive layer may contain a pigment compound (for example, a pigment compound having an absorption spectrum with a maximum absorption wavelength in a wavelength range of 380nm to 430 nm) instead of or in combination with the ultraviolet absorber. The pigment compound can suppress degradation of the OLED element and degradation of the high refractive index component due to ultraviolet light.

The 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, still 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, acrylic polymer). The amount of the acrylic polymer is preferably 20 parts by weight or less, more preferably 15 parts by weight or less, still 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, based on 100 parts by weight of the acrylic polymer. The addition amount of the pigment compound in the above range is preferable because light in a region which does not affect light emission of the OLED element can be sufficiently absorbed and the use of the adhesive layer formed of the adhesive composition can suppress degradation of the OLED element and degradation of the high refractive index component.

Any one of the ultraviolet absorber and the pigment compound may be used, and the ultraviolet absorber and the pigment compound are preferably used in combination. According to the ultraviolet absorber, for example, light having a wavelength of 380nm can be absorbed, but light having a wavelength range (380 nm to 430 nm) shorter than the light emitting region (longer than 430 nm) of the OLED element may not be sufficiently absorbed, and the transmitted light may be degraded. The dye compound can suppress the transmission of light having a wavelength (380 nm to 430 nm) on a wavelength side shorter than the light emitting region (a wavelength side longer than 430 nm) of the OLED element, and the use of the ultraviolet absorber and the dye compound in combination can sufficiently ensure the transmittance of visible light in the light emitting region of the OLED element.

In the present invention, by using such a pigment compound in combination with an ultraviolet absorber, light in a region (wavelength 380nm to 430 nm) which does not affect light emission of the OLED element can be sufficiently absorbed, and the light emitting region (wavelength side longer than 430 nm) of the OLED element can be sufficiently transmitted, and as a result, degradation of the OLED element due to external light and degradation of the high refractive index component can be simultaneously suppressed. In the case where the ultraviolet absorber and the pigment 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, based on 100 parts by weight of the base polymer (for example, acrylic polymer). The pigment compound is preferably 0.1 to 20 parts by weight, more preferably 0.1 to 10 parts by weight, and even more preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the base polymer (for example, acrylic polymer).

The maximum absorption wavelength in the dye compound is an absorption maximum wavelength that exhibits maximum absorbance when a plurality of maximum absorptions exist in a spectroscopic absorption spectrum in a wavelength region of 300nm to 460 nm. The maximum absorption wavelength of the absorption spectrum of the dye compound is more preferably in the wavelength region of 380nm to 420 nm. The pigment compound is not particularly limited as long as it has the wavelength characteristics, and a material having no fluorescence or phosphorescence (photoluminescence) is preferable, which does not hinder the display performance of the OLED element.

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.

As the organic pigment compound, a commercially available organic pigment compound can be preferably used. Specifically, the indole compound may be BONASORB UA-3911 (trade name, maximum absorption wavelength of absorption spectrum: 398nm, manufactured by Orient chemical industry Co., ltd.), the cinnamic acid compound may be SOM-5-0106 (trade name, maximum absorption wavelength of absorption spectrum: 416nm, manufactured by Orient chemical industry Co., ltd.), the porphyrin compound may be FDB-001 (trade name, maximum absorption wavelength of absorption spectrum: 420nm, manufactured by mountain land chemical industry Co., ltd.), the cyanine compound may be merocyanine compound (trade name: FDB-009, maximum absorption wavelength of absorption spectrum: 394nm, manufactured by mountain land chemical industry Co., ltd.), or the like. Among them, from the viewpoint of suppressing crosslinking inhibition and optical reliability, cyanine compounds are preferable, and polymethylene compounds are particularly preferable.

Examples of the dye compound include a compound represented by the following formula (1A) (hereinafter, sometimes referred to as a compound (1A)) as a cyanine compound. In the case where a cis-trans isomer is present in the compound (1A), the compound (1A) contains any one of its cis-trans isomers. In addition, in the case where 1 or more asymmetric carbon atoms are present in the compound (1A), the compound (1A) contains any one of a compound in which each asymmetric carbon atom is in an R configuration, a compound in an S configuration, and a compound in any combination thereof. Also included are their racemic compounds, racemic mixtures, single enantiomers and diastereomeric mixtures.

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

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, cyano group, nitro group, trifluoromethyl group, heterocyclic ring-containing group, -C (O) -R ⁷ OR-SO ₂-R⁸.R⁷ represents a hydroxyl group OR-OR ⁷¹,R⁸ represents a halogen atom, Hydroxy, -OR ⁸¹、-NR⁸²R⁸³ OR-R ⁸⁴.R⁷¹ and R ⁸¹～R⁸⁴, which are the same OR different, 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 each represents a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent, -NR ⁴⁰⁶R⁴⁰⁷、-OR⁴⁰⁸, cyano group, -C (O) R ⁴⁰⁹、-O-C(O)R⁴¹⁰ OR-C (O) OR ⁴¹¹,R⁴⁰⁴～R⁴¹¹ are the same OR different and each represents a hydrogen atom, An alkyl group which may have a substituent or an aryl group which may have a substituent. the nitrogen atom to which R ⁴⁰⁴、R⁴⁰⁵、R⁴⁰⁴ and R ⁴⁰⁵ are bonded may form a 4-to 8-membered nitrogen-containing heterocyclic ring (heterocyclic ring containing a nitrogen atom as a ring constituting atom) which may have a substituent.

The preferred embodiment and production method of the compound (1A) are not particularly limited, and for example, can be produced by the method described in japanese patent application laid-open No. 2018-200463.

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

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.

In the case of using a crosslinking agent in the formation of the adhesive layer, the amount of the crosslinking agent used is not particularly limited, but is preferably 0.001 parts by weight or more, more preferably 0.01 parts by weight or more, based on 100 parts by weight of the base polymer, from the viewpoint of obtaining sufficient adhesive reliability. 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 adequate flexibility in the adhesive layer and improving the adhesive force.

The adhesive layer (particularly, acrylic adhesive layer) may contain a silane coupling agent from the viewpoint of improving the adhesion reliability under humidified conditions, particularly, from the viewpoint of improving the adhesion reliability to glass. The silane coupling agent may be used alone or in combination of two or more. When the pressure-sensitive adhesive layer contains a silane coupling agent, the adhesiveness under wet conditions, particularly the adhesiveness to glass, can be improved.

The silane coupling agent is not particularly limited, and examples thereof include gamma-glycidoxypropyl trimethoxysilane, gamma-glycidoxypropyl triethoxysilane, gamma-aminopropyl trimethoxysilane, and N-phenyl-aminopropyl trimethoxysilane. Further, as the silane coupling agent, for example, a commercially available product such as a trade name "KBM-403" (manufactured by Xinyue chemical industries, ltd.) can be cited. Among them, the silane coupling agent is preferably gamma-glycidoxypropyl trimethoxysilane.

When the adhesive layer contains a silane coupling agent, the content of the silane coupling agent in the adhesive layer (particularly, the acrylic adhesive layer) is not particularly limited, but is preferably 0.01 parts by weight or more, more preferably 0.02 parts by weight or more, based on 100 parts by weight of the base polymer. The upper limit of the content of the silane coupling agent is preferably 10 parts by weight or less, more preferably 1 part by weight or less, based on 100 parts by weight of the base polymer.

The pressure-sensitive adhesive layer may contain additives such as a light stabilizer, a crosslinking accelerator, a tackifying resin (rosin derivative, polyterpene resin, petroleum resin, oil-soluble phenol resin, etc.), a deterioration inhibitor, a filler, a colorant (pigment, dye, etc.), an antioxidant, a chain transfer agent, a plasticizer, a softener, a surfactant, an antistatic agent, etc., as necessary, within a range that does not impair the effects of the present invention. In addition, such additives may be used singly or in combination of two or more.

The method for producing the adhesive layer (particularly, acrylic adhesive layer) is not particularly limited, and examples thereof include coating (application) the adhesive composition onto a substrate (including a resin layer and a glass layer described later) or a release liner, drying and curing the resulting adhesive composition layer, and coating (application) the adhesive composition onto a substrate (including a resin layer and a glass layer described later) or a release liner, and curing the resulting adhesive composition layer by irradiation with an active energy ray. Further, if necessary, the heat drying may be further performed.

Examples of the active energy ray include ionizing radiation such as α rays, β rays, γ rays, neutron rays, and electron rays, ultraviolet rays, and the like, and ultraviolet rays are particularly preferable. The irradiation energy, irradiation time, irradiation method, and the like of the active energy ray are not particularly limited.

The adhesive composition can be prepared by a known or conventional method. For example, the solvent-type acrylic adhesive composition can be produced by mixing an additive (for example, an ultraviolet absorber or the like) as necessary in a solution containing the acrylic polymer. For example, the active energy ray-curable acrylic pressure-sensitive adhesive composition can be produced by mixing an additive (for example, an ultraviolet absorber or the like) as necessary with a mixture of the aforementioned acrylic monomers or a partial polymer thereof. The adhesive composition may be applied (coated) by a known coating method. For example, a gravure roll coater, a reverse roll coater, a roll lick coater, a dip roll coater, a bar coater, a blade coater, a spray coater, a comma coater, a direct coater, or the like may be used.

In particular, when the adhesive layer is formed using an active energy ray-curable adhesive composition, the active energy ray-curable adhesive composition preferably contains a photopolymerization initiator. When the active energy ray-curable adhesive composition contains an ultraviolet absorber, the photopolymerization initiator preferably contains at least a photopolymerization initiator having light absorption characteristics in a wide wavelength range. For example, it is preferable to include at least a photopolymerization initiator having light absorption characteristics to visible light in addition to ultraviolet light. This is because there is a concern that curing by active energy rays is hindered by the action of an ultraviolet absorber, and when a photopolymerization initiator having light absorption characteristics in a wide wavelength range is contained, high photocurability is easily obtained in the adhesive composition.

(Adhesive layer)

The adhesive layer is a layer capable of bonding substances by being sandwiched between adherends, and is a layer that does not have a practical adhesive strength when the adherends adhered by the adhesive layer are peeled off.

As the adhesive for forming the adhesive layer constituting the optical element, various adhesives can be used, and examples thereof include isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latex adhesives, and aqueous polyesters. These adhesives are generally used as adhesives (aqueous adhesives) containing an aqueous solution and contain 0.5 to 60% by weight of a solid component.

The adhesive may contain a crosslinking agent and an additive. Examples of the additives include coupling agents such as silane coupling agents and titanium coupling agents, adhesion promoters such as ethylene oxide, ultraviolet absorbers, deterioration inhibitors, dyes, processing aids, ion capturing agents, antioxidants, tackifiers, fillers, plasticizers, leveling agents, foaming inhibitors, antistatic agents, heat stabilizers, and hydrolysis stabilizers.

(Resin layer)

The resin layer constituting the optical element is not particularly limited, and for example, a plastic film may be cited. As the material of the plastic film and the like, for example, a polyester resin such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), a Cyclic Olefin Polymer (COP), polycarbonate (PC), polyether ether ketone (PEEK), and transparent polyimide (CPI) which are excellent in dimensional stability and hardly shrink are preferable. It should be noted that two or more of these plastic materials may be used singly or in combination. The release liner that is peeled off when the optical element is used (when attached) is not contained in the "resin layer".

The resin layer is preferably transparent. The total light transmittance in the visible light wavelength region of the resin layer (according to JISK 7361-1) is not particularly limited, and is preferably 85% or more, more preferably 88% or more.

The refractive index difference between the adhesive layer and the resin layer (the absolute value of the refractive index of the adhesive layer "-" the refractive index of the resin layer ") in the present invention is not particularly limited, but is preferably 2 or less, preferably 1 or less, more preferably 0.5 or less, and particularly preferably 0.3 or less from the viewpoints of improving the interface antireflection property and improving the light collecting rate of light emitted from the OLED element. In the case where the resin layer includes a multilayer structure of two or more continuous layers, the refractive index difference is measured by considering the two or more layers as one resin layer.

The thickness of the resin layer is not particularly limited, and is preferably 10 μm to 80 μm, for example. The resin layer may have any of a single layer and a plurality of layers. The surface of the resin layer may be subjected to a known and conventional surface treatment such as physical treatment, e.g., corona discharge treatment and plasma treatment, and chemical treatment, e.g., primer treatment. In the case where the resin layer includes a continuous multilayer structure of two or more layers, the thickness is measured by considering the two or more layers as one resin layer.

The resin layer preferably contains an ultraviolet absorber (UVA) and a dye compound having an absorption spectrum with a maximum absorption wavelength in a wavelength range of 380nm to 430 nm. When the resin layer contains the ultraviolet absorber and the pigment 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. In addition, 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, the resin layer preferably contains the ultraviolet absorber and the dye compound, so that the content of the ultraviolet absorber and the dye compound in the adhesive layer can be reduced, and precipitation and bleeding of the ultraviolet absorber and the dye compound in the adhesive layer can be suppressed.

As the ultraviolet absorber (UVA) and the dye compound contained in the resin layer, the same ultraviolet absorber and the same dye compound contained in the pressure-sensitive adhesive layer can be used. The ultraviolet absorber and the pigment compound may be used singly or in combination.

When the resin layer contains the ultraviolet absorber and the dye compound, the content of each of the ultraviolet absorber and the dye compound in the resin layer is not particularly limited, but is preferably 0.01 wt% or more, more preferably 0.05 wt% or more, and even more preferably 0.1 wt% or more, based on 100 wt% of the resin layer, from the viewpoint of suppressing deterioration of the OLED element due to ultraviolet rays contained in external light and obtaining an OLED display device excellent in weather resistance without using a polarizing plate. In addition, from the viewpoint of suppressing occurrence of yellowing phenomenon of the adhesive agent accompanying addition of the ultraviolet absorber, and obtaining excellent optical characteristics, high transparency, and excellent appearance characteristics, 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 further preferably 8% by weight or less relative to 100% by weight of the resin layer.

In the case where both the resin layer and the pressure-sensitive adhesive layer contain an ultraviolet absorber and the pigment compound, the total amount thereof may be adjusted to the above range.

(Glass layer)

The glass layer constituting the optical element is not particularly limited, and an appropriate glass layer may be used according to purposes. Examples of the glass layer include soda lime glass, boric acid glass, aluminosilicate glass, and quartz glass, depending on the classification based on the composition. In addition, alkali-free glass and low alkali glass can be cited according to the classification based on alkali components. The content of the alkali metal component (for example, na ₂O、K₂O、Li₂ O) in the glass is preferably 15 wt% or less, more preferably 10 wt% or less.

(Hard coat)

The hard coat layer constituting the optical element may be formed of any appropriate resin as long as it has sufficient surface hardness, excellent mechanical strength, and excellent light transmittance. Specific examples of the resin include thermosetting resins, thermoplastic resins, ultraviolet curable resins, and the like.

Examples of the ultraviolet curable resin include ultraviolet curable resins such as polyesters, acrylics, carbamates, amides, silicones, and epoxies. The ultraviolet curable resin includes ultraviolet curable monomers, oligomers, and polymers. The preferable ultraviolet curable resin includes a resin composition containing an acrylic monomer component or oligomer component having preferably 2 or more, more preferably 3 to 6 ultraviolet polymerizable functional groups. The ultraviolet curable resin may be blended with a photopolymerization initiator.

(Antireflection layer)

Any suitable constitution may be used for the antireflection layer constituting the optical element, and examples thereof include (i) a single layer of a low refractive index layer having an optical film thickness of 120nm to 140nm and a refractive index of 1.35 to 1.55, (ii) a laminate of 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.

Examples of the material capable of forming the low refractive index layer include silicon oxide (SiO ₂) and magnesium fluoride (MgF ₂). The refractive index of the low refractive index layer is typically about 1.35 to about 1.55. Examples of the material capable of forming the high refractive index layer include titanium oxide (TiO ₂), niobium oxide (Nb ₂O₃ or Nb ₂O₅), tin-doped indium oxide (ITO), and the like. The refractive index of the high refractive index layer is typically about 1.60 to about 2.20. Examples of the material capable of forming the medium refractive index layer include titanium oxide (TiO ₂), a mixture of a material capable of forming a low refractive index layer and a material capable of forming 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 about 1.85. The thicknesses of the low refractive index layer, the medium refractive index layer, and the high refractive index layer may be set so as to achieve an appropriate optical film thickness corresponding to the layer structure of the antireflection layer, the desired antireflection performance, and the like.

(Antiglare layer)

As the antiglare layer constituting the optical element, a known antiglare layer can be used without limitation, and is generally formed as a layer in which inorganic or organic particles as an antiglare agent are dispersed in a resin.

The antiglare layer is not particularly limited, and is formed, for example, using an antiglare layer-forming material containing a resin, particles, and a thixotropic agent, and the particles and the thixotropic agent are aggregated to form convex portions on the surface of the antiglare layer. With this configuration, the antiglare layer has excellent display characteristics that both antiglare property and prevention of white blurring, and even if the antiglare layer is formed by aggregation of particles, the occurrence of a protrusion on the surface of the antiglare layer, which is an appearance defect, can be prevented, thereby improving the yield of the product.

(Intermediate layer)

An intermediate layer constituting an optical element is formed between the resin layer and the hard coat layer, antireflection layer, or antiglare layer. By forming the intermediate layer, the adhesion between the resin layer and the hard coat layer, the antireflection layer, or the antiglare layer is improved.

The resin contained in the intermediate layer is not particularly limited, and may be, for example, a resin obtained by mixing (compatibilizing) the resin contained in the resin layer with the resin contained in the hard coat layer, the antireflection layer, or the antiglare layer alone. The resin contained in the intermediate layer may be, for example, a resin that is chemically changed by heating, light irradiation, or the like between the resin contained in the resin layer and at least one of the resin contained in the hard coat layer, the antireflection layer, or the antiglare layer.

(Impact absorbing layer)

The impact absorbing layer constituting the optical element may be composed of any appropriate resin layer capable of achieving a desired impact absorption rate. The resin layer may be formed of a resin film or an adhesive. The impact absorbing layer typically comprises an epoxy resin, a urethane resin or an acrylic resin. These resins may be used alone or in combination.

(Antistatic layer)

The antistatic layer constituting the optical element is not particularly limited, and is formed by, for example, coating a conductive coating liquid containing a conductive polymer.

(Method for producing optical laminate)

The method for producing the optical laminate is not particularly limited, and it may be produced by sequentially laminating an adhesive layer, a resin layer, a glass layer, a hard coat layer, an antireflection layer, an antiglare layer, an intermediate layer (compatible layer), an impact absorbing layer, and the like constituting the optical element on the visual recognition side of the OLED display panel, or may be produced by preliminarily producing a laminate constituting the optical laminate and laminating the laminate on the visual recognition side of the OLED display panel. In the case of previously manufacturing a laminate constituting the optical laminate, the laminate may be a laminate constituting the whole of the optical laminate, or a laminate constituting a part of the optical laminate may be separately laminated on the viewing side of the OLED display panel. The layer constituting the optical element or the laminate thereof may be protected with a release liner or a surface protective film before use.

(Release liner)

The adhesive layer may be provided with a release liner on the surface (adhesive face) of the adhesive layer before use. The release liner may be used as a protective material for the adhesive layer, and is peeled off when attached to an adherend. The release liner is not a component constituting the optical element, and may not be provided.

(Surface protective film)

The outermost surface (outermost surface on the visual recognition side) of the optical laminate may be protected by a surface protective film. The surface protective film may also be applied by the consumer. The surface protective film is not necessarily a component constituting the optical element, and may not be provided. As the surface protective film, a known or conventional surface protective film may be used, and there is no particular limitation, and for example, a surface protective film having an adhesive layer on the surface of a plastic film may be used.

(OLED display device of the invention)

An embodiment of an OLED display device in which an optical laminate is laminated on the visual recognition side of an OLED display panel will be described below 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 a basic configuration of an OLED display device in which an optical laminate is laminated.

As shown in fig. 2, the OLED display device 200 is laminated with layers constituting the optical laminate 20 on the visual recognition side (upper side in fig. 2) of the OLED display panel 100. The OLED display panel 100 is not particularly limited, and may have the same structure as the OLED display panel 100 shown in fig. 1, for example.

In the OLED display device 200 of fig. 2, 21 to 29 are layers constituting the optical laminate 20, 21 represents an adhesive layer or an adhesive layer, 22 represents a resin layer, a glass layer or an impact absorbing layer, 23 represents a hard coat layer or an antiglare layer, 24 represents an adhesive layer or an adhesive layer, 25 represents a resin layer, a glass layer or an impact absorbing layer, 26 represents an adhesive layer or an adhesive layer, 27 represents a resin layer, a glass layer or an impact absorbing layer, 28 represents a hard coat layer or an antiglare layer, 29 represents an antireflection layer, and any one of 21, 24, 26 is an adhesive layer. The laminated structure of the optical laminate 20 shown in fig. 2 is not limited to the present embodiment, and other layers constituting the optical element may be interposed between any layers of the laminated structure of the optical laminate 20 shown in fig. 2, or any layers of the laminated structure of the optical laminate 20 shown in fig. 2 may be absent.

In fig. 3 (a) - (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.

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

The adhesive film obtained by the above-described operation is temporarily adhered to the OLED display panel 100 in fig. 3 (c). In fig. 3 (c), the adhesive layer 31 of the adhesive film is in contact with the visually recognized side (upper side) of the OLED display panel 100.

In the case where the adhesive film 300 has the base material 32, an adhesive film in which the release liner 33 is omitted may be used. By winding the adhesive film 300, the adhesive surface of the adhesive layer 31 that does not face the substrate 32 may be protected by contact with the surface of the substrate 32 where the adhesive layer 31 is not present (roll form). In the case of the adhesive film having the roll form, the surface of the adhesive layer 31 is exposed before the adhesive film is attached to the OLED display panel 100, and the exposed surface of the adhesive layer 31 is attached to the surface of the OLED display panel 100, whereby the adhesive film is temporarily attached to the OLED display panel 100.

In the adhesive film temporarily adhered to the adherend, the adhesive force of the adhesive layer 31 is increased by applying an adhesive force increasing treatment to the adhesive layer 31, and the adherend is fixed to the substrate 32 by the adhesive layer 31.

In this specification, "fixation" refers to a state in which two layers stacked are firmly glued and it is impossible or difficult to peel them at the interface of the two. The term "temporary adhesion" means a state in which the adhesion between two layers stacked is small and can be easily peeled off at the interface between the two layers.

Examples

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

Example 1 production of adhesive film 1

Preparation of (meth) acrylic polymers

A four-necked flask equipped with a stirrer, a thermometer, a nitrogen inlet tube and a condenser was charged with a monomer mixture comprising 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). Further, 0.1 part by weight of 2,2' -azobisisobutyronitrile as a polymerization initiator was added together with ethyl acetate with respect to 100 parts by weight of the monomer mixture (solid content), nitrogen was introduced while stirring slowly, thereby performing nitrogen substitution, and then the liquid temperature in the flask was maintained at around 55 ℃ to perform polymerization for 7 hours. Then, ethyl acetate was added to the obtained reaction solution to adjust the concentration of the solid content to 30%, thereby preparing a solution of a (meth) acrylic polymer having a weight average molecular weight of 200 ten thousand.

Preparation of acrylic adhesive composition 1

An acrylic adhesive composition 1 was prepared by blending 100 parts by weight of the solid content of the resulting (meth) acrylic polymer solution with 2.3 parts by weight of an ultraviolet absorber (2, 4-bis- [ {4- (4-ethylhexyl oxy) -4-hydroxy } -phenyl ] -6- (4-methoxyphenyl) -1,3, 5-triazine, trade name: tinosorb S, manufactured by BASF corporation), 3.5 parts by weight of a pigment compound (polymethylene compound of the following formula (3)), 0.1 part by weight of an isocyanate-based crosslinking agent (trade name: TAKENATE D N, trimethylol propane xylylene diisocyanate, manufactured by Sanjing chemical Co., ltd.), 0.3 parts by weight of benzoyl peroxide (trade name: NYPER BMT, manufactured by Japanese fat and oil Co., ltd.) as a peroxide-based crosslinking agent, and 0.08 parts by weight of a silane coupling agent (trade name: KBM403, manufactured by Sangyo chemical Co., ltd.).

Production of adhesive film 1

The acrylic adhesive composition 1 was uniformly applied to the surface of a polyethylene terephthalate film (PET film, transparent substrate, release liner) having a thickness of 38 μm after treatment with a silicone-based release agent by means of a fountain coater, and dried in an air circulation type constant temperature oven at 155 ℃ for 2 minutes, thereby forming an adhesive layer having a thickness of 20 μm. Next, the obtained adhesive layer was peeled off from the PET film, thereby producing an adhesive film 1. Adhesive film 1 corresponds to "substrate-less adhesive film".

EXAMPLE 2 preparation of adhesive film 2

Preparation of acrylic adhesive composition 2

An acrylic pressure-sensitive adhesive composition 2 was prepared in the same manner as in example 1, except that the amount of the ultraviolet absorber to be blended was 1.3 parts by weight and the amount of the pigment compound to be blended was 4.3 parts by weight, based on 100 parts by weight of the solid content of the (meth) acrylic polymer solution.

Production of adhesive film 2

The acrylic adhesive composition 2 was uniformly applied to the surface of a polyethylene terephthalate film (PET film, transparent substrate, release liner) having a thickness of 38 μm treated with a silicone-based release agent by means of a fountain coater, and dried in an air circulation type constant temperature oven at 155 ℃ for 2 minutes, thereby forming an adhesive layer having a thickness of 20 μm. Next, the adhesive film 2 was produced by adhering the adhesive film to a transparent plastic film base material (manufactured by acrylic film, toyo Steel plate Co., ltd., trade name "HX40UF", thickness: 40 μm) and peeling the PET film. The adhesive film 2 corresponds to "adhesive film with a base material".

EXAMPLE 3 preparation of adhesive film 3

Preparation of acrylic adhesive composition 3

An acrylic pressure-sensitive adhesive composition 3 was prepared in the same manner as in example 1, except that the amount of the ultraviolet absorber to be blended was 0.8 part by weight and the amount of the pigment compound to be blended was 2.3 parts by weight, based on 100 parts by weight of the solid content of the (meth) acrylic polymer solution.

Production of adhesive film 3

The acrylic adhesive composition 3 was uniformly applied to the surface of a polyethylene terephthalate film (PET film, transparent substrate, release liner) having a thickness of 38 μm treated with a silicone-based release agent by means of a fountain coater, and dried in an air circulation type constant temperature oven at 155 ℃ for 2 minutes, thereby forming an adhesive layer having a thickness of 40 μm. Next, the PET film was peeled off after being adhered to a base material (trade name "RV20", manufactured by eastern steel sheet (ltd.) with a thickness of 20 μm), to thereby manufacture an adhesive film 3. The adhesive film 3 corresponds to "adhesive film with a base material".

Comparative example 1 production of adhesive film 4

An acrylic adhesive composition 4 was prepared in the same manner as in example 1, except that a composition not containing an ultraviolet absorber was used as the acrylic adhesive composition 1. An adhesive film 4 was produced in the same manner as in example 1, except that the acrylic adhesive composition 4 was used. The adhesive film 4 corresponds to "a substrate-less adhesive film".

Comparative example 2 production of adhesive film 5

The acrylic adhesive composition 4 was uniformly applied to the surface of a polyethylene terephthalate film (PET film, transparent substrate, release liner) having a thickness of 38 μm after treatment with a silicone-based release agent by means of a fountain coater, and dried in an air circulation type constant temperature oven at 155 ℃ for 2 minutes, thereby forming an adhesive layer having a thickness of 20 μm. Next, the adhesive film 5 was produced by adhering the adhesive film to a transparent plastic film base material (manufactured by acrylic film, toyo Steel plate Co., ltd., trade name "HX40UF", thickness: 40 μm) and peeling the PET film. The adhesive film 5 corresponds to "adhesive film with a base material".

Comparative example 3 production of adhesive film 6

The acrylic adhesive composition 4 was uniformly applied to the surface of a polyethylene terephthalate film (PET film, transparent substrate, release liner) having a thickness of 38 μm treated with a silicone-based release agent by means of a fountain coater, and dried in an air circulation type constant temperature oven at 155 ℃ for 2 minutes, thereby forming an adhesive layer having a thickness of 40 μm. Next, the PET film was peeled off after being adhered to a base material (trade name "RV20", manufactured by eastern steel sheet (ltd.) with a thickness of 20 μm), to thereby manufacture an adhesive film 6. The adhesive film 6 corresponds to "adhesive film with a base material".

Evaluation

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

((Measurement of weight average molecular weight (Mw) of (meth) acrylic Polymer)

The weight average molecular weight (Mw) of the resulting (meth) acrylic polymer was measured by GPC (gel permeation chromatography).

Analytical device HLC-8120 GPC manufactured by Tosoh Corp

Column manufactured by Tosoh corporation, G7000 HXL+GMHXL+GMHXL

Column dimensions 7.8mm phi.times.30 cm each, totaling 90cm

Column temperature of 40 DEG C

Flow rate 0.8 ml/min

Injection amount 100. Mu.l

Eluent tetrahydrofuran

Detector differential Refractometer (RI)

Standard sample polystyrene

(Evaluation of moisture permeability)

The adhesive films obtained in examples and comparative examples were examined for moisture permeability. Specifically, the moisture permeability (g/m ². Multidot.24 hours) of the adhesive film was measured in accordance with JIS Z0208 under an environment having a temperature of 40℃and a relative humidity of 92%. The results are shown in Table 1.

(Determination of light transmittance)

The adhesive films obtained in examples and comparative examples were bonded to a glass plate to obtain test samples. The light transmittance spectrum at room temperature (23 ℃) was measured by a visible ultraviolet spectrophotometer (spectrophotometer U4100, manufactured by Hitachi high Co., ltd.) and the light transmittance (%) at 380nm was read. Similarly, the light transmittance (%) at a wavelength of 450nm was measured. The results are shown in Table 1.

(Measurement of transmittance ratio of transmittance before and after humidification)

After the adhesive films obtained in examples and comparative examples were exposed to an environment having a temperature of 85 ℃ and a relative humidity of 85% for 240 hours, the change ratio of light transmittance before and after humidification at a wavelength of 380nm was calculated according to the following formula.

Fluctuation ratio of transmittance of specific wavelength before and after humidification= (transmittance of specific wavelength after humidification)/(transmittance of initial specific wavelength)

The results are shown in Table 1 as "fluctuation ratio of transmittance at 380nm (after 240 hours) before and after 85℃at 85%.

(Measurement of loss factor (tan. Delta.))

The adhesive films obtained in examples and comparative examples were punched out to a size of Φ8mm using a jig, and probes for ARES-G2 (TA instruments) were provided. The measurement was performed at intervals of 5℃in the range from-50℃to 200℃under a strain of 0.05% and a frequency of 1 Hz. Peak top values of peaks of loss factors (tan δ) were extracted from the obtained data (fig. 4). The results are shown in "loss factor (tan δ)" in table 1. It is understood that, although only the peak having the loss factor (tan δ) in the region of 0 ℃ or lower in example 1 and comparative example 1 is shown in fig. 4, the peak having the loss factor (tan δ) in the region of 0 ℃ or lower in example 2 and example 3 is also shown.

(Evaluation of impact force)

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

Preparation of evaluation sample

The pressure-sensitive paper (PRESCALE film manufactured by fuji film co., ltd.) was attached to one surface of the pressure-sensitive adhesive layer or (2) the surface of the pressure-sensitive adhesive layer opposite to the surface to which the base material was attached, to the pressure-sensitive films described in examples and comparative examples, thereby obtaining samples in which the base material, the pressure-sensitive paper, and the pressure-sensitive paper were laminated in this order. The obtained sample was autoclaved (50 ℃ C., 0.5MPa,15 minutes) to obtain an evaluation sample. The adhesive films 1 and 4 for the above (1) and the examples 1 and comparative example and the adhesive films for the other examples and comparative example and the above (2).

Test method

1 The evaluation samples of examples 1 to 3 and comparative examples 1 to 3 were set on a table of a ball drop impact tester (X of FIG. 5). In fig. 5, X1 is a substrate, X2 is an adhesive layer, and X3 is pressure-sensitive paper. In the evaluation samples of example 1 and comparative example 1, X1 was not present.

10G of iron balls (X4 of FIG. 5) were placed at a height of 30cm (X5 of FIG. 5).

3, The iron ball was dropped, and the impact force was measured by a sensor located under the table, and the results are shown in Table 1.

Claims

1. An adhesive film for an OLED display device, which is used for an OLED display device in which only an optical element having a polarization degree of 95% or less is laminated on the visual recognition side of an OLED element,

The adhesive film for an OLED display device has at least one layer containing an ultraviolet absorber as a layer constituting the optical element,

The adhesive film for an OLED display device has an adhesive layer having a peak of a loss factor (tan delta) at a region of 0 ℃ or less, the peak having a peak top value of 1.5 or more,

The adhesive film for an OLED display device has a light transmittance of 20% or less at 380 nm.

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

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

4. An OLED display device in which only an optical element having a polarization degree of 95% or less is laminated on a visual recognition side of an OLED element,

The OLED display device comprising the adhesive film according to claim 1 or 2.