JP2023126055A - Optical laminate for oled display device, and oled display device - Google Patents

Abstract

To provide an optical laminate for an OLED display device and an OLED display device which can suppress a folding trace and peeling at the time of folding.SOLUTION: An optical laminate 910 for an OLED display device is an optical laminate for an OLED display device having a resin layer 92 and an adhesive layer 91, wherein a dimensional change rate D1(%) to 85°C from room temperature in the resin layer and a dimensional change rate D2(%) of the resin layer after having been kept at 85°C for 5 hours after having reached at 85°C satisfy the following expression (A), and a creep amount Cr70 at 70°C of the adhesive layer is 200 μm or less. Expression (A): D1-D2≤0.4.SELECTED DRAWING: Figure 9

Description

The present invention relates to an optical laminate for an OLED display and an OLED display.

OLED (Organic light emitting diode) display devices have advantages in display performance compared to liquid crystal display devices, such as higher visibility, less viewing angle dependence, and faster response speed. Further, since the OLED display device does not use a backlight, it is advantageous for making it thinner, and it can also be used as a foldable device that can be flexibly curved or folded.

An OLED display device typically has an OLED element in which an anode, an OLED layer including a light emitting layer, and a cathode are stacked in this order. Since the electrodes (anode or cathode) of OLED elements are made of transparent conductive materials with a high refractive index such as ITO or metal materials with high reflectance, external light is reflected by the electrodes, resulting in decreased contrast and internal reflection. A problem of reflection may occur, and the display performance of the OLED display device may deteriorate.

In order to suppress the adverse effects of external light reflection, a proposal has been made to arrange a polarizing plate and a circularly polarizing plate such as a λ/4 plate on the viewing side of an OLED display device (for example, Patent Document 1). Such a circularly polarizing plate also has the function of blocking ultraviolet rays contained in external light and preventing deterioration of OLED elements due to ultraviolet rays. Furthermore, due to the mechanical properties of the circularly polarizing plate itself, it also has the function of absorbing external impact and preventing damage to the OLED display device.

On the other hand, when a circularly polarizing plate is used, the efficiency of light utilization is poor due to absorption by the polarizing plate, resulting in low brightness. Increasing the emission intensity of an OLED element to obtain desired brightness increases power consumption and shortens the life of the OLED element. In addition, the polarizing plate has a thickness of about 0.15 mm if an adhesive layer for pasting is included, which is disadvantageous for making the OLED display device thinner. Furthermore, since circularly polarizing plates are expensive, there is also the problem of increased manufacturing costs.

In addition, in order to make the OLED display device thinner and reduce manufacturing costs, instead of using a circularly polarizing plate, a color filter is placed on the viewing side of the OLED element, and the color filter is colored in the same color as the OLED layer emitted light. A method of aligning the filters has been proposed (for example, Patent Document 2).

As one type of OLED display device, an OLED display device having a microcavity (multiple reflection interference, also referred to as an optical resonator or a microresonator) structure is known. According to an OLED display device having a microcavity structure, the spectrum of the light extracted to the outside becomes steep and high intensity, so it is said that 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 viewing side of the OLED element in order to provide functions such as surface protection and flexibility. ing.

Japanese Patent Application Publication No. 2003-332068 Japanese Patent Application Publication No. 2018-112715 Japanese Patent Application Publication No. 2015-207377

In this way, OLED display devices that can be used as foldable devices have been put into practical use. However, when these display devices are folded, crease marks may occur on the surface of the display device. Moreover, peeling of members constituting the display device may occur. In this way, OLED display devices used as foldable devices are required to have greater flexibility.

Therefore, an object of the present invention is to provide an optical laminate for an OLED display device and an OLED display device with high flexibility. More specifically, it is an object of the present invention to provide an optical laminate for an OLED display device and an OLED display device that are less likely to cause crease marks and less likely to cause peeling of members constituting the display device when folded.

As a result of intensive studies to achieve the above object, the present inventors found that in an OLED display device, the dimensional change rate D1 (%) of the base material from room temperature to 85°C and 5 hours after reaching 85°C. , the dimensional change rate D2 (%) of the base material after being maintained at 85°C satisfies a specific formula, and the creep amount Cr ₇₀ of the adhesive layer determined by a test under specific conditions is below a specific value. The inventors have discovered that the optical laminate for an OLED display device and the OLED display device exhibit high flexibility due to certain factors, and have completed the present invention.

That is, the present invention is an optical laminate for an OLED display device having a resin layer and an adhesive layer,
The dimensional change rate D1 (%) of the resin layer from room temperature to 85°C and the dimensional change rate D2 (%) of the resin layer after being maintained at 85°C for 5 hours after reaching 85°C are as follows. satisfies formula (A),
The present invention provides an optical laminate for an OLED display device, in which the adhesive layer has a creep amount Cr ₇₀ of 200 μm or less as determined by the following test at 70°C.
Test: A test piece having an adhesive layer of 20 mm in length x 30 mm in width is placed on one end of a stainless steel test plate, and the bonding surface between the test plate and the adhesive layer is 20 mm in length x 20 mm in width, and Attach it so that it protrudes 10 mm horizontally from the part. With the test plate fixed so that one end to which the test piece is not bonded is vertically upward and one end to which the test piece is bonded is vertically downward, a weight is fixed to the center of the lower end of the test piece to give a weight of 500gf. Apply a load vertically downward. The amount of creep (amount of deviation) of the adhesive layer relative to the test plate 3600 seconds after the start of applying the load is measured.
D1-D2≦0.4 (A)

The 500% modulus of the adhesive layer is preferably 0.05 to 0.2 N/mm ² .

The OLED display device is preferably an OLED display device in which only an optical element having a degree of polarization of 80% or less is laminated on the viewing side of the OLED element.

The storage modulus G' of the adhesive layer at 25° C. is 1×10 ⁵ Pa or less,
The peak value of tan δ, which indicates the glass transition temperature (Tg) of the pressure-sensitive adhesive layer, is preferably 3 or less.

The loss modulus G'' of the pressure-sensitive adhesive layer at 25° C. is preferably 1×10 ⁵ Pa or less.

The adhesive layer preferably contains a (meth)acrylic polymer.

The resin layer and the adhesive layer are preferably laminated adjacent to each other.

The resin layer preferably contains at least one selected from the group consisting of polyimide and cycloolefin polymer.

The present invention comprises an OLED display panel and the optical laminate for an OLED display device according to any one of claims 1 to 10, which is laminated on the OLED display panel,
The present invention also provides an OLED display device in which the optical laminate for an OLED display device is located on a viewing side of the image display panel.

According to the present invention, it is possible to provide an optical laminate for an OLED display device and an OLED display device that can suppress folding marks and peeling when folded.

1 is a schematic cross-sectional view showing one embodiment of an OLED display panel used in an OLED display device of the present invention. 1 is a schematic cross-sectional view showing an embodiment of an OLED display device in which an optical laminate of the present invention is laminated. 1 is a schematic cross-sectional view showing an embodiment of an OLED display device in which an optical laminate of the present invention is laminated. 1 is a schematic cross-sectional view showing an embodiment of an OLED display device in which an optical laminate of the present invention is laminated. 1 is a schematic cross-sectional view showing an embodiment of an OLED display device in which an optical laminate of the present invention is laminated. 1 is a schematic cross-sectional view showing an embodiment of an OLED display device in which an optical laminate of the present invention is laminated. 1 is a schematic cross-sectional view showing an embodiment of an OLED display device in which an optical laminate of the present invention is laminated. 1 is a schematic cross-sectional view showing an embodiment of an OLED display device in which an optical laminate of the present invention is laminated. 1 is a schematic cross-sectional view showing an embodiment of an OLED display device in which an optical laminate of the present invention is laminated. It is a figure for demonstrating the measuring method of the creep amount about an adhesive layer. FIG. 3 is a diagram for explaining a bending retention test. It is a figure for demonstrating the bending angle of the optical laminated body for OLED display devices after the bending retention test. FIG. 3 is a diagram for explaining a continuous bending test. (A) It is a side view showing an example of an OLED display device. (B) It is a side view when the OLED display device shown in (A) is folded. (C) In (B), it is a figure for demonstrating the calculation method of the strain produced in the resin layer of an OLED display device. (A) It is a side view which shows another example of an OLED display device. (B) It is a figure for demonstrating the calculation method of the strain produced in the resin layer of an OLED display device in (A). (A) It is a side view which shows another example of an OLED display device. (B) It is a figure for demonstrating the calculation method of the strain produced in the resin layer of an OLED display device in (A).

The present invention provides an optical laminate for an OLED display and an OLED display. The optical laminate for an OLED display device of the present invention is referred to as the "optical laminate of the present invention"; the OLED display device using the optical laminate of the present invention is referred to as the "OLED display device of the present invention"; An optical element that does this may be referred to as an "optical element of the present invention". The optical laminate of the present invention is a laminate obtained by removing the OLED display panel from the OLED display device of the present invention.

In the OLED display device of the present invention, only an optical element with a polarization degree of 95% or less may be laminated on the OLED display panel on the viewing side of the OLED element, or one or more optical elements with a polarization degree of 95% or more on the viewing side of the OLED element. More than 100 optical elements may be stacked. "Only optical elements with a polarization degree of 95% or less are laminated on the viewing side of the OLED element" means that optical elements with a polarization degree of over 95% are not included in the optical elements on the viewing side of the OLED element. do. "Optical elements with a degree of polarization exceeding 95%" include, but are not limited to, polarizing plates such as linear polarizing plates, 1/4 retardation plates, 1/2 retardation plates, circular polarizing plates, and reflective polarizing plates. included. That is, the OLED display device of the present invention may be an OLED display device that does not include a polarizing plate on the viewing side of the OLED element, or may be an OLED display device that includes a polarizing plate on the viewing side of the OLED element.

The degree of polarization is determined by the following formula based on parallel transmittance Tp and cross transmittance Tc measured using an ultraviolet-visible spectrophotometer and corrected for visibility.
Degree of polarization (%) = {(Tp-Tc)/(Tp+Tc)}1/2×100

When the OLED display device of the present invention includes a polarizing plate on the viewing side of the OLED element, antireflection properties, shock absorption properties, and ultraviolet absorption properties tend to improve.

When the OLED display device of the present invention does not include a polarizing plate on the viewing side of the OLED element, absorption of light emitted from the OLED element by the polarizing plate is suppressed, improving the lighting rate and saving power consumption. This leads to a longer service life. Further, by not using a polarizing plate, it is possible to make the device thinner, and manufacturing costs can be reduced.

The optical laminate of the present invention is an optical laminate for an OLED display device having a resin layer and an adhesive layer, and the dimensional change rate D1 (%) of the resin layer from room temperature to 85°C and The dimensional change rate D2 (%) of the resin layer after being maintained at 85°C for 5 hours after reaching the temperature satisfies the following formula (A), and the creep amount of the adhesive layer was determined by the following test at 70°C. Cr ₇₀ is 200 μm or less.
Test: A test piece having an adhesive layer of 20 mm in length x 30 mm in width is placed on one end of a stainless steel test plate, and the bonding surface between the test plate and the adhesive layer is 20 mm in length x 20 mm in width, and Attach it so that it protrudes 10 mm horizontally from the part. With the test plate fixed so that one end to which the test piece is not bonded is vertically upward and one end to which the test piece is bonded is vertically downward, a weight is fixed to the center of the lower end of the test piece to give a weight of 500gf. Apply a load vertically downward. The amount of creep (amount of deviation) of the adhesive layer relative to the test plate 3600 seconds after the start of applying the load is measured.
D1-D2≦0.4 (A)

It is preferable that the optical laminate of the present invention has the above-mentioned characteristics in that folding marks and peeling can be suppressed when the OLED display device is bent. Furthermore, the optical laminate of the present invention may include optical elements other than the adhesive layer and resin layer that are laminated on the OLED display device of the present invention.

Each configuration will be explained below.

(OLED display panel)
An OLED display panel includes, as essential components, an OLED element in which an anode, an OLED layer including a light emitting layer, and a cathode are stacked in this order. The optical laminate of the present invention is laminated on the viewing side of the OLED elements of an OLED display panel.

Hereinafter, one 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 includes a red OLED element 12R in which a transparent electrode 11a, a red OLED layer 10R that emits red light, a back electrode 11b are laminated in this order, a transparent electrode 11a, and a red OLED layer 10R that emits red light. A green OLED element 12G in which a green OLED layer 10G that emits light and a back electrode 11b are stacked in this order, a transparent electrode 11a, and a blue OLED in which a blue OLED layer 10B that emits blue light and a back electrode 11b are stacked in this order. It has an element 12B. OLED elements 12R, 12G, and 12B of each plurality of colors are arranged in order on the substrate 13. A TFT (Thin Film Transistor) layer 14 is formed on the surface of the substrate 13 on which each OLED element is arranged, and is connected to the back electrode 11b of each of the OLED elements 12R, 12G, and 12B of a plurality of colors.

In the OLED display panel 100 of FIG. 1, a color filter 15 is arranged on the viewing side (upper side in FIG. 1) of each of the plurality of color OLED elements 12R, 12G, and 12B. The color filter 15 includes a red colored layer 15R, a green colored layer 15G, and a blue colored layer 15B, and a black matrix layer 16 is provided between each colored layer. However, the color filter 15 is not an essential component.

When the color filter 15 is not arranged in the OLED display panel 100, it is preferable that the OLED display device includes a polarizing plate on the viewing side of the OLED element. On the other hand, when the color filter 15 is arranged in the OLED display panel 100, the OLED display device may include a polarizing plate on the viewing side of the OLED element, but it is preferable that it does not include a polarizing plate.

In FIG. 1, the color filter 15 is arranged such that a red colored layer 15R, a green colored layer 15G, and a blue colored layer 15B face a red OLED element 12R, a green OLED element 12G, and a blue OLED element 12B, respectively. has been done.

The transparent electrode 11a is either a cathode or an anode, and is generally provided as a cathode. Transparent conductive materials such as ITO (indium tin oxide), indium oxide, IZO (indium zinc oxide), SnO ₂ , and ZnO are used as the material for forming the transparent electrode 11a.

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

A bonding layer 17 is provided between the substrate 13 and the color filter 15. The bonding layer 17 has translucency. As the material for the bonding layer 17, any material used in general OLED display devices may be used, and for example, a photocurable resin such as a photosensitive polyimide resin, a thermosetting resin, or the like may be used.

In addition to the configuration shown in FIG. 1, the OLED display panel 100 includes configurations that an OLED display panel has, such as a hole injection layer, a hole transport layer, an electron transport layer, a sealing layer, and a touch sensor panel. (not shown).

The feature of the OLED display panel of FIG. 1 is that a color filter 15 is arranged on each of the OLED elements 12R, 12G, and 12B of a plurality of colors so that colored layers 15R, 15G, and 15B of the same color face each other. It is that it is placed. As shown in FIG. 1, external light W, which is white, passes through, for example, a red colored layer 15R, and further passes through a transparent electrode 11a and a red OLED layer 10R that emits red light, and then reaches a back electrode 11b. The reflected light G passes through the red OLED layer 10R, the transparent electrode 11a, and the red colored layer 15R again, and enters the observer's eyes.

Since the green and blue components of the external light W are absorbed by the red colored layer 15R, the light intensity is reduced to 1/3. Further, since the reflected light G passes through the red colored layer 15R and the red OLED layer 10R again, this causes attenuation. Further, since the reflected light G has a red color, the red light emitted from the OLED layer 10R can be enhanced. Similarly, when external light W is incident on the green colored layer 15G and the blue colored layer 15B, green light and blue light can be respectively enhanced. Therefore, by using a color filter in combination with an OLED display panel, it is possible to significantly suppress reflection of external light and improve the luminous intensity of the OLED element even when a polarizing plate is not used for antireflection.

However, color filters are generally prone to interference unevenness due to their regular two-dimensional structure.
In addition, color filters have a problem in that reflection is likely to occur at the interface and the rate of light taken in from the OLED element is reduced.
In addition, color filters do not have sufficient ultraviolet absorption function compared to the case of using polarizing plates, and OLED elements tend to deteriorate over time due to ultraviolet rays contained in external light (i.e., have low weather resistance). be.
Additionally, color filters have a problem in that they do not have a sufficient impact absorption function compared to the case where polarizing plates are used.

Further, the OLED display panel 100 of this embodiment has a microcavity structure. Light generated from the OLED layers 10R, 10G, and 10B passes through the transparent electrode 11a and is emitted to the outside. Here, the emitted light includes "direct light" emitted directly from the OLED layers 10R, 10G, 10B toward the transparent electrode 11a, and "direct light" emitted from the OLED layers 10R, 10G, 10B toward the back electrode 11b, Both components of the reflected light directed toward the transparent electrode 11a after being reflected by the electrode 11b are included. That is, a first optical path C1 in which a part of the light emitted from the OLED layers 10R, 10G, and 10B proceeds to the transparent electrode 11a side without proceeding to the back electrode 11b side, and is emitted to the outside through the transparent electrode 11a; The remaining part of the light emitted from the OLED layers 10R, 10G, and 10B travels toward the back electrode 11b, is reflected by the back electrode 11b, and then is emitted to the outside through the OLED layers 10R, 10B, 10B, and the transparent electrode 11a. A second optical path C2 is formed. The thicknesses of the OLED layers 10R, 10G, and 10B are made different so that the light components corresponding to each color are strengthened by interference between the direct light and the reflected light. That is, the OLED layer is designed so that the optical path length between the back electrode (positive electrode) 11b and the transparent electrode (negative electrode) 11a matches the EL spectrum peak wavelength of each of red, green, and blue, and the strongest light is extracted from each color. 10R, 10G, and 10B have different thicknesses. Specifically, the short wavelength blue OLED layer 10B is designed to be thin, and the long wavelength red OLED layer 10R is designed to be thick. The light generated in the OLED layer is repeatedly reflected between the positive and negative electrodes, and by resonating and emphasizing only the light with wavelengths that match the optical path length, and weakening the light with other wavelengths that have mismatched optical path lengths. , the spectrum of light extracted to the outside becomes steeper and more intense, improving brightness and color purity.
Although an OLED display panel with a microcavity structure has the excellent effect of improving brightness and color purity, it has the problem of strong viewing angle dependence (narrow viewing angle) due to its steep spectrum. may occur. For this reason, when an image is viewed from an angle during image display, a color shift may occur that makes the image appear to be a different color from the color originally desired to be displayed.

(Optical element of the present invention)
The optical element of the present invention is an optical element laminated on the viewing side of an OLED display device, and includes at least an adhesive layer and a resin layer. The optical element of the present invention is further selected from a polarizing plate, an adhesive layer, a glass layer, a hard coat layer, an antireflection layer, an antiglare layer, an intermediate layer (compatible layer), a shock absorption layer, an antistatic layer, etc. It may include at least one layer.

(Adhesive layer)
An adhesive layer is a layer that has adhesive properties at room temperature and adheres to an adherend with light pressure.Even when an adherend that has been attached to the adhesive layer is peeled off, the adhesive layer remains practical. A substance that maintains a strong adhesive force.

The adhesive layer of the present invention is not particularly limited, but preferably has light scattering properties (a function of scattering light) from the viewpoint of efficiently reducing color shift and interference unevenness of an OLED display device. When the adhesive layer of the present invention has light scattering properties, it is preferable that the adhesive layer contains light scattering fine particles dispersed therein.

When the OLED display device of the present invention includes a color filter on the viewing side and the adhesive layer has light scattering properties, color shift and interference unevenness of the OLED display device can be reduced, and the OLED display device caused by light scattering can be reduced. From the viewpoint of suppressing image blur, it is preferable that the distance between the adhesive layer having light scattering properties and the color filter is 700 μm or less. From the viewpoint of suppressing image blurring of an OLED display device caused by light scattering, the distance between the adhesive layer having light scattering properties and the color filter is more preferably 600 μm or less, and 500 μm or less. is more preferred, and most preferred is 0 μm, that is, the adhesive layer having light scattering properties is in direct contact with the color filter.

The distance between the adhesive layer having light scattering properties and the color filter is the distance (μm) between the surface of the adhesive layer in the color filter direction and the surface of the color filter in the adhesive layer direction. If another layer is laminated between the pressure-sensitive adhesive layer having light scattering properties and the color filter, the thickness (μm) of the other layer (if there are two or more layers, the total) corresponds to

The haze value of the adhesive layer of the present invention is not particularly limited, but from the viewpoint of efficiently reducing color shifts and interference unevenness of OLED display devices, it is preferably 20% or more, more preferably 30% or more, and still more preferably It is 40% or more, particularly preferably 50% or more. Further, from the viewpoint of suppressing image blurring of an OLED display device and displaying a high-definition image, the haze value of the adhesive layer of the present invention is preferably 90% or less, more preferably 80% or less, and 70% or less. More preferred.

The total light transmittance of the adhesive layer of the present invention is not particularly limited, but from the viewpoint of ensuring the brightness of the OLED display device, the total light transmittance is preferably 60% or more, more preferably 70% or more, still more preferably 80% or more, Particularly preferably, it is 90% or more. Further, the upper limit of the total light transmittance of the adhesive layer of the present invention is not particularly limited, but may be less than 100%, 99.9% or less, or 99% or less.

The haze value and total light transmittance of the adhesive of the present invention can be measured by the methods defined in JIS 7136 and JIS 7361, respectively, and are determined by the type and thickness of the adhesive layer, the type of light-scattering fine particles described below, It can be controlled by the amount added.

The thickness of the adhesive layer of the present invention is preferably 10 to 100 μm, more preferably 15 to 90 μm, and 20 to 80 μm from the viewpoint of efficiently reducing color shift and interference unevenness of an OLED display device. The thickness is more preferably 25 to 70 μm.

The light-scattering fine particles have an appropriate refractive index difference with the pressure-sensitive adhesive layer and impart light-scattering properties to the pressure-sensitive adhesive layer. It is preferable that the pressure-sensitive adhesive layer contains light-scattering fine particles because this imparts light-scattering performance. Examples of the light-scattering fine particles include inorganic fine particles and polymer fine particles. Examples of the material for the inorganic fine particles include silica, calcium carbonate, aluminum hydroxide, magnesium hydroxide, clay, talc, and titanium dioxide. Examples of the material of the polymer fine particles include silicone resin, acrylic resin, methacrylic resin (eg, polymethyl methacrylate), polystyrene resin, polyurethane resin, melamine resin, polyethylene resin, and epoxy resin. The light-scattering fine particles are preferably polymeric fine particles, and in particular, fine particles composed of silicone resin (for example, Tospear series manufactured by Momentive Performance Materials Japan) have excellent dispersion in the adhesive layer. An adhesive layer with excellent scattering performance that has a suitable refractive index difference with respect to the adhesive layer, exhibits uniform haze within the plane, and reduces color shift and interference unevenness in OLED display devices. It is suitable for this purpose. The shape of the light-scattering fine particles may be, for example, spherical, flat, or irregular. The light-scattering fine particles may be used alone or in combination of two or more types.

The average particle diameter of the light-scattering fine particles is preferably 0.1 μm or more, more preferably 0.15 μm or more, still more preferably 0.2 μm or more, and especially from the viewpoint of imparting appropriate light-scattering properties to the adhesive layer. Preferably it is 0.25 μm or more. In addition, the average particle diameter of the light-scattering fine particles is preferably 12 μm or less, more preferably 10 μm or less, and even more preferably 8 μm, from the viewpoint of preventing the haze value from becoming too high and displaying a high-definition image. It is as follows. The average particle diameter can be measured using, for example, a Coulter counter.

The refractive index of the light scattering fine particles is preferably 1.2 to 5, more preferably 1.25 to 4.5, and may be 1.3 to 4, or 1.35 to 3.

The absolute value of the refractive index difference between the light-scattering fine particles and the adhesive layer (the adhesive layer excluding the light-scattering fine particles) is a point of view for efficiently reducing color shifts and interference unevenness in OLED display devices. , preferably 0.001 or more, more preferably 0.01 or more, even more preferably 0.02 or more, particularly preferably 0.03 or more, and may be 0.04 or more, or 0.05 or more. . Further, the absolute value of the refractive index difference between the light-scattering fine particles and the adhesive layer is preferably 5. or less, more preferably 4 or less, still more preferably 3 or less.

From the viewpoint of imparting appropriate light scattering properties to the adhesive layer, the content of light-scattering fine particles in the adhesive layer is preferably 0.01 parts by weight based on 100 parts by weight of the adhesive constituting the adhesive layer. The amount is at least 0.05 parts by weight, more preferably at least 0.1 parts by weight, particularly preferably at least 0.15 parts by weight. In addition, the content of light-scattering fine particles is adjusted to 100 parts by weight of the adhesive constituting the adhesive layer, from the viewpoint of preventing the haze value from becoming too high, suppressing image blurring, and displaying a high-definition image. On the other hand, it is preferably 80 parts by weight or less, more preferably 70 parts by weight or less.

The adhesive layer of the present invention is not particularly limited, but preferably has a high refractive index from the viewpoint of preventing interface reflection and improving the rate of light emitted from the OLED element. The refractive index of the adhesive layer of the present invention is preferably 1.57 or more, more preferably 1.575 or more, and more preferably 1.57 or more, from the viewpoint of preventing interface reflection and improving the lighting rate of light emitted from the OLED element. It is preferably 1.580 or more, particularly preferably 1.585 or more, even more preferably 1.590 or more, and may be 1.595 or more.
The refractive index of the adhesive layer of the present invention can be adjusted by the type and content of the aromatic ring-containing monomer and high refractive index organic material described below.

The variation ratio of the refractive index before and after humidification of the adhesive layer of the present invention is not particularly limited, but it can prevent interface reflection and stably improve the lighting rate of light emitted from the OLED element even in a high temperature and high humidity environment. From this point of view, it is preferably 0.05 or less, preferably 0.04 or less, more preferably 0.02 or less, particularly preferably 0.01 or less.

The variation ratio of the refractive index before and after humidification of the adhesive layer of the present invention can be calculated using the following formula after storing the adhesive layer of the present invention in a humidified environment at a temperature of 85°C and a relative humidity of 85% for 120 hours. It is.
Change ratio of refractive index before and after humidification = |Initial refractive index - refractive index after humidification|/(Initial refractive index)
The variation ratio of the refractive index before and after humidification depends on the type and content of the aromatic ring-containing monomer, high refractive index organic material, and high refractive index inorganic material described below, the type of adhesive constituting the adhesive layer, monomer composition, degree of crosslinking, It can be adjusted depending on the thickness etc.

The adhesive constituting the adhesive layer of the present invention is not particularly limited, but includes, for example, an acrylic adhesive, a rubber adhesive, a vinyl alkyl ether adhesive, a silicone adhesive, a polyester adhesive, and a polyamide adhesive. Examples include adhesives, urethane adhesives, fluorine adhesives, and epoxy adhesives. Among these, acrylic pressure-sensitive adhesives are preferred as the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer in terms of transparency, adhesiveness, weather resistance, cost, and ease of designing the pressure-sensitive adhesive. That is, the adhesive layer of the present invention is preferably an acrylic adhesive layer made of an acrylic adhesive. The pressure-sensitive adhesives can be used alone 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 the molecule) as a monomer component constituting the polymer. The acrylic polymer is preferably a polymer containing an alkyl (meth)acrylic acid ester as a monomer component constituting the polymer. Note that the acrylic polymers can be used alone or in combination of two or more.

The adhesive composition forming the adhesive layer of the present invention may be in any form. For example, the adhesive composition may be of an emulsion type, a solvent type (solution type), an active energy ray-curable type, a heat melt type (hot melt type), or the like. Among these, solvent-based and active energy ray-curable adhesive compositions are preferred from the viewpoint of productivity and the ease of obtaining an adhesive layer with excellent optical properties and appearance.

That is, the adhesive layer of the present invention is an acrylic adhesive layer containing an acrylic polymer as a base polymer, and is preferably formed from a solvent-type or active energy ray-curable acrylic adhesive composition.

Examples of the active energy rays include ionizing radiation such as α rays, β rays, γ rays, neutron beams, and electron beams, and ultraviolet rays, with ultraviolet rays being particularly preferred. That is, the active energy ray-curable adhesive composition is preferably an ultraviolet ray-curable adhesive composition.

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

The acrylic polymer is a polymer composed (formed) of an acrylic monomer as an essential monomer component. The acrylic polymer is preferably a polymer composed (formed) of (meth)acrylic acid alkyl ester as an essential monomer component. That is, the acrylic polymer preferably contains an alkyl (meth)acrylate ester as a structural unit. In the present specification, "(meth)acrylic" refers to "acrylic" and/or "methacrylic" (either or both of "acrylic" and "methacrylic"), and the same applies to the others. In addition, the said acrylic polymer is comprised from 1 type, or 2 or more types of monomer components.

As the (meth)acrylic acid alkyl ester as an essential monomer component, a (meth)acrylic acid alkyl ester having a linear or branched alkyl group is preferably mentioned. In addition, (meth)acrylic acid alkyl ester can be used individually or in combination of 2 or more types.

The (meth)acrylic acid alkyl ester having a linear or branched alkyl group is not particularly limited, but includes, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, ( Isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, (meth)acrylate Isopentyl acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, (meth) ) Isononyl acrylate, (meth)decyl acrylate, (meth)isodecyl acrylate, (meth)undecyl acrylate, (meth)dodecyl acrylate, (meth)tridecyl acrylate, (meth)tetradecyl acrylate, (meth) Pentadecyl acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate (stearyl (meth)acrylate), isostearyl (meth)acrylate, nonadecyl (meth)acrylate, (meth)acrylic Examples include (meth)acrylic acid alkyl esters having a linear or branched alkyl group having 1 to 30 carbon atoms, such as eicosyl acid. Among them, from the viewpoint of flexibility, (meth)acrylic acid alkyl esters having a linear or branched alkyl group having 6 to 30 carbon atoms (hereinafter referred to as "(meth)acrylic acid alkyl esters having a long-chain alkyl group") ) is preferred, and n-dodecyl (meth)acrylate (lauryl (meth)acrylate) is more preferred. By using a (meth)acrylic acid alkyl ester having a long-chain alkyl group, the entanglement of the polymer is reduced, and the laminate of the present invention tends to be more easily deformed and the flexibility of the laminate of the present invention is improved. There is. In addition, from the viewpoint of flexibility and adhesion at low temperatures, it is also preferable to use a (meth)acrylic acid alkyl ester whose homopolymer has a glass transition temperature (Tg) of -70°C to -20°C. - It is more preferable to use ethylhexyl acrylate. One type or two or more types of (meth)acrylic acid alkyl esters can be used. Note that "minor distortion" means that in an optical laminate for an OLED display device, for example, the surface portion of the laminate 3 mm away from the apex of the bent portion is distorted by about ±0 to 10%. "+" indicates strain in the tensile direction, and "-" indicates strain in the compressive direction. Normally, a "+" tensile strain is applied to the outside of the bend (convex side), a "-" compressive strain is applied to the inside of the bend (concave side), and strain stress is applied inside the laminate to be bent. There is a neutral axis where is 0.

The proportion of the (meth)acrylic acid alkyl ester in all monomer components (100% by weight) constituting the acrylic polymer is not particularly limited, but is 50% by weight or more (for example, 50 to 100% by weight). It is preferably 53 to 90% by weight, and even more preferably 55 to 85% by weight.

The acrylic polymer may contain a copolymerizable monomer together with the (meth)acrylic acid alkyl ester as a monomer component constituting the polymer. That is, the acrylic polymer may contain a copolymerizable monomer as a structural unit. Note that the copolymerizable monomers can be used alone or in combination of two or more types.

The copolymerizable monomer is not particularly limited, but it is possible to obtain a pressure-sensitive adhesive layer with a high refractive index, suppress reflection at the interface with the OLED display panel, and improve the light absorption rate from the OLED element. Preferred examples include monomers having an aromatic ring. That is, the acrylic polymer preferably contains a monomer having an aromatic ring in the molecule as a structural unit.

The monomer having an aromatic ring in the molecule is a monomer (monomer) having at least one aromatic ring in the molecule (in one molecule). In this specification, the above-mentioned "monomer having an aromatic ring in the molecule" may be 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 type of such compounds can be used alone or two or more types can be used in combination.

Examples of the ethylenically unsaturated group include a (meth)acryloyl group, a vinyl group, and a (meth)allyl group. A (meth)acryloyl group is preferred from the viewpoint of polymerization reactivity, and an acryloyl group is more preferred from the viewpoint of flexibility and adhesiveness. From the viewpoint of suppressing a decrease in flexibility of the adhesive, a compound having one ethylenically unsaturated group in one molecule (ie, a monofunctional monomer) is preferably used as the aromatic ring-containing monomer.

The number of aromatic rings contained in one molecule of the compound used as the aromatic ring-containing monomer may be one or two or more. The upper limit of the number of aromatic rings contained in the aromatic ring-containing monomer is not particularly limited, and may be, for example, 16 or less. From the viewpoint of ease of preparation of the acrylic polymer and transparency of the adhesive, the number of aromatic rings may be, for example, 12 or less, preferably 8 or less, more preferably 6 or less, and 5 or less. It may be less than or equal to 4, it may be less than or equal to 3, and it may be less than or equal to 2.

The aromatic ring possessed by the compound used as the aromatic ring-containing monomer includes, for example, a benzene ring (it can be a benzene ring that forms part of a biphenyl structure or a fluorene structure); a naphthalene ring, an indene ring, an azulene ring, an anthracene ring, and a phenanthrene ring. It may be a carbocyclic ring such as a condensed ring, such as a pyridine ring, a pyrimidine ring, a pyridazine ring, a pyrazine ring, a triazine ring, a pyrrole ring, a pyrazole ring, an imidazole ring, a triazole ring, an oxazole ring, an isoxazole ring, and a thiazole ring. It may be a ring or a heterocyclic ring such as a thiophene ring. The heteroatoms included as ring constituent atoms in the heterocycle may be, for example, one or more heteroatoms selected from the group consisting of nitrogen, sulfur, and oxygen. The heteroatoms constituting the heterocycle may be one or both of nitrogen and sulfur. The aromatic ring-containing monomer may have a structure in which one or more carbon rings and one or more heterocycles are condensed, such as a dinaphthothiophene structure.

The aromatic ring (preferably a carbocyclic ring) may have one or more substituents on the ring-constituting atoms, or may have no substituents. When having a substituent, the substituent includes an alkyl group, an alkoxy group, an aryloxy group, a hydroxyl group, a halogen atom (fluorine atom, chlorine atom, bromine atom, etc.), a hydroxyalkyl group, a hydroxyalkyloxy group, a glycidyloxy group. Examples include, but are not limited to. In a substituent containing carbon atoms, the number of carbon atoms contained in the substituent is preferably 1 to 4, more preferably 1 to 3, and may be 1 or 2, for example. The aromatic ring has no substituent on the ring constituent atoms or has one or more substituents selected from the group consisting of an alkyl group, an alkoxy group, and a halogen atom (for example, a bromine atom). obtain. Note that the phrase "the aromatic ring of the aromatic ring-containing monomer has a substituent on its ring-constituting atoms" means that the aromatic ring has a substituent other than the substituent having an ethylenically unsaturated group.

The aromatic ring and the ethylenically unsaturated group may be bonded directly or may be bonded via a linking group. The linking group is, for example, an alkylene group, an oxyalkylene group, a poly(oxyalkylene) group, a phenyl group, an alkylphenyl group, an alkoxyphenyl group, or a structure in which one or more hydrogen atoms in these groups are substituted with a hydroxyl group. It may be a group containing one or more structures selected from a group such as a hydroxyalkylene group (for example, a hydroxyalkylene group), an oxy group (-O- group), a thiooxy group (-S- group), and the like. An aromatic structure in which an aromatic ring and an ethylenically unsaturated group are bonded directly or via a linking group selected from the group consisting of an alkylene group, an oxyalkylene group, and a poly(oxyalkylene) group. Ring-containing monomers can be preferably employed. The number of carbon atoms in the alkylene group and the oxyalkylene group is preferably 1 to 4, more preferably 1 to 3, and may be 1 or 2, for example. The number of repeating oxyalkylene units in the poly(oxyalkylene) group may be, for example, 2 to 3.

Examples of compounds that can be preferably employed as the aromatic ring-containing monomer include aromatic ring-containing (meth)acrylates and aromatic ring-containing vinyl compounds. The aromatic ring-containing (meth)acrylate and the aromatic ring-containing vinyl compound can each be used singly or in combination of two or more. One or more aromatic ring-containing (meth)acrylates and one or more aromatic ring-containing vinyl compounds may be used in combination.

When the acrylic polymer contains the aromatic ring-containing monomer as a monomer component constituting the polymer, the proportion of the aromatic ring-containing monomer in the total monomer components (100% by weight) constituting the acrylic polymer is: Although not particularly limited, it is preferably 30% by weight or more, more preferably 50% by weight or more, still more preferably 60% by weight or more, and may be 70% by weight or more. It is preferable that the ratio is 30% by weight or more because it tends to make it easier to obtain a higher refractive index. From the viewpoint of making it easier to obtain a higher refractive index, the content of the aromatic ring-containing monomer may be, for example, more than 70% by weight, 75% by weight or more, 80% by weight or more, or 85% by weight or more. It may be 90% by weight or more, or 95% by weight or more. In addition, the upper limit of the proportion of the aromatic ring-containing monomer is preferably 99% by weight or less, more preferably 98% by weight or less, from the viewpoint of obtaining an adhesive layer with appropriate flexibility and an adhesive layer with excellent transparency. % or less, more preferably 97% by weight or less, and may be 96% by weight or less. Further, the content of the aromatic ring-containing monomer may be 93% by weight or less, 90% by weight or less, 80% by weight or less, or 75% by weight or less. In some embodiments where more emphasis is placed on adhesive properties and/or optical properties, the content of the aromatic ring-containing monomer may be 70% by weight or less, 60% by weight or less, or 45% by weight or less.

As the aromatic ring-containing monomer, a monomer having two or more aromatic rings (preferably carbocycles) in one molecule can be preferably employed since it is easy to obtain a high refractive index effect. Examples of monomers having two or more aromatic rings in one molecule (hereinafter also referred to as "monomers containing multiple aromatic rings") include monomers having a structure in which two or more non-fused aromatic rings are bonded via a linking group. , a monomer having a structure in which two or more non-fused aromatic rings are chemically bonded directly (i.e., without intervening other atoms), a monomer having a fused aromatic ring structure, a monomer having a fluorene structure, a monomer having a dinaphthothiophene structure , monomers having a dibenzothiophene structure, and the like. The monomer containing multiple aromatic rings can be used alone or in combination of two or more.

The linking group is, for example, an oxy group (-O-), a thiooxy group (-S-), an oxyalkylene group (for example, a -O-(CH ₂ ) _n - group, where n is 1 to 3, preferably 1). , thiooxyalkylene groups (e.g. -S-(CH ₂ ) _n - group, where n is 1 to 3, preferably 1), linear alkylene groups (i.e. -(CH ₂ ) _n - group, where n is 1 to 6, preferably 1 to 3), the alkylene group in the oxyalkylene group, the thiooxyalkylene group, and the linear alkylene group may be a partially halogenated or completely halogenated group. From the viewpoint of the flexibility of the adhesive, preferred examples of the linking group include an oxy group, a thiooxy group, an oxyalkylene group, and a straight-chain alkylene group. Specific examples of monomers having a structure in which two or more non-fused aromatic rings are bonded via a linking group include phenoxybenzyl (meth)acrylate (for example, m-phenoxybenzyl (meth)acrylate), thiophenoxybenzyl (meth) Examples include acrylate, benzylbenzyl (meth)acrylate, and the like.

The monomer having a structure in which two or more non-fused aromatic rings are directly chemically bonded may be, for example, biphenyl structure-containing (meth)acrylate, triphenyl structure-containing (meth)acrylate, vinyl group-containing biphenyl, or the like. Specific examples include o-phenylphenol (meth)acrylate, biphenylmethyl (meth)acrylate, and the like.

Examples of the monomer having the fused aromatic ring structure include naphthalene ring-containing (meth)acrylate, anthracene ring-containing (meth)acrylate, vinyl group-containing naphthalene, vinyl group-containing anthracene, and the like. Specific examples include 1-naphthylmethyl (meth)acrylate (also known as 1-naphthalenemethyl (meth)acrylate), hydroxyethylated β-naphthol acrylate, 2-naphthoethyl (meth)acrylate, 2-naphthoxyethyl acrylate, -(4-methoxy-1-naphthoxy)ethyl (meth)acrylate and the like.

Specific examples of the monomer having the fluorene structure include 9,9-bis(4-hydroxyphenyl)fluorene (meth)acrylate, 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene (meth)acrylate etc. In addition, since the monomer having a fluorene structure includes a structural part in which two benzene rings are directly chemically bonded, it is included in the concept of a monomer having a structure in which two or more non-fused aromatic rings are directly chemically bonded.

Examples of the monomer having the dinaphthothiophene structure include (meth)acryloyl group-containing dinaphthothiophene, vinyl group-containing dinaphthothiophene, (meth)allyl group-containing dinaphthothiophene, and the like. Specific examples include (meth)acryloyloxymethyl dinaphthothiophene (for example, a compound having a structure in which CH ₂ CH(R ¹ )C(O)OCH ₂ - is bonded to the 5th or 6th position of the dinaphthothiophene ring. , R ¹ is a hydrogen atom or a methyl group), (meth)acryloyloxyethyldinaphthothiophene (for example, CH ₂ CH(R ¹ )C(O) at the 5th or 6th position of the dinaphthothiophene ring A compound with a structure in which OCH(CH ₃ )- or CH ₂ CH(R ¹ )C(O)OCH ₂ CH ₂ - is bonded. Here, R ¹ is a hydrogen atom or a methyl group), vinyldinaphthothiophene (For example, a compound having a structure in which a vinyl group is bonded to the 5th or 6th position of the naphthothiophene ring), (meth)allyloxydinaphthothiophene, and the like. Note that monomers having a dinaphthothiophene structure are included in the concept of monomers having a fused aromatic ring structure because they include a naphthalene structure and also because they have a structure in which a thiophene ring and two naphthalene structures are condensed. Ru.

Examples of the monomer having the dibenzothiophene structure include (meth)acryloyl group-containing dibenzothiophene, vinyl group-containing dibenzothiophene, and the like. Note that a monomer having a dibenzothiophene structure has a structure in which a thiophene ring and two benzene rings are condensed, and therefore is included in the concept of a monomer having a condensed aromatic ring structure.
Note that neither the dinaphthothiophene structure nor the dibenzothiophene structure corresponds to a structure in which two or more non-fused aromatic rings are directly chemically bonded.

As the aromatic ring-containing monomer, a monomer having one aromatic ring (preferably a carbon ring) in one molecule may be used. A monomer having one aromatic ring in one molecule can be useful, for example, in improving the flexibility of the adhesive, adjusting the adhesive properties, and improving transparency. A monomer having one aromatic ring in one molecule is preferably used in combination with a monomer containing multiple aromatic rings from the viewpoint of improving the refractive index of the adhesive.

Examples of monomers having one aromatic ring in one molecule include benzyl (meth)acrylate, methoxybenzyl (meth)acrylate, phenyl (meth)acrylate, ethoxylated phenol (meth)acrylate, and phenoxypropyl (meth)acrylate. , phenoxybutyl (meth)acrylate, cresyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, chlorobenzyl (meth)acrylate, and other carbon aromatic ring-containing (meth)acrylates; 2-(4, 6-dibromo-2-s-butylphenoxy)ethyl (meth)acrylate, 2-(4,6-dibromo-2-isopropylphenoxy)ethyl (meth)acrylate, 6-(4,6-dibromo-2-s- Butylphenoxy)hexyl (meth)acrylate, 6-(4,6-dibromo-2-isopropylphenoxy)hexyl (meth)acrylate, 2,6-dibromo-4-nonylphenyl acrylate, 2,6-dibromo-4-dodecyl Bromine-substituted aromatic ring-containing (meth)acrylates such as phenyl acrylate; carbon aromatic ring-containing vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, tert-butylstyrene; N-vinylpyridine, N-vinylpyrimidine, N-vinylpyridine, N-vinylpyrimidine, Examples include compounds having a vinyl substituent on a heteroaromatic ring, such as -vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, and N-vinyloxazole.

As the aromatic ring-containing monomer, monomers having a structure in which an oxyethylene chain is interposed between the ethylenically unsaturated group and the aromatic ring in the various aromatic ring-containing monomers described above may be used. A monomer in which an oxyethylene chain is interposed between an ethylenically unsaturated group and an aromatic ring can be understood as an ethoxylated product of the original monomer. The number of repeating oxyethylene units (-CH ₂ CH ₂ O-) in the oxyethylene chain is typically 1 to 4, preferably 1 to 3, more preferably 1 to 2, for example 1. Specific examples of ethoxylated aromatic ring-containing monomers include ethoxylated o-phenylphenol (meth)acrylate, ethoxylated nonylphenol (meth)acrylate, ethoxylated cresol (meth)acrylate, phenoxyethyl (meth)acrylate, and phenoxydiethylene glycol. Examples include di(meth)acrylate.

The content of the monomer containing multiple aromatic rings in the aromatic ring-containing monomer is not particularly limited, and may be, for example, 5% by weight or more, 25% by weight or more, or 40% by weight or more. From the viewpoint of facilitating the realization of a pressure-sensitive adhesive having a higher refractive index, the content of the monomer containing multiple aromatic rings in the aromatic ring-containing monomer may be, for example, 50% by weight or more, and preferably 70% by weight or more. , 85% by weight or more, 90% by weight or more, or 95% by weight or more. Substantially 100% by weight of the aromatic ring-containing monomer may be a monomer containing multiple aromatic rings. That is, as the aromatic ring-containing monomer, only one or more aromatic ring-containing monomers may be used. Further, for example, in consideration of the balance between high refractive index and adhesive properties and/or optical properties, the content of the monomer containing multiple aromatic rings in the aromatic ring-containing monomer may be less than 100% by weight, and may be 98% by weight. It may be less than 90% by weight, it may be less than 80% by weight, and it may be less than 65% by weight. Considering adhesive properties and/or optical properties, the content of the monomer containing multiple aromatic rings in the aromatic ring-containing monomer may be 70% by weight or less, may be 50% by weight or less, may be 25% by weight or less, and may be 10% by weight or less. It may be less than %. An embodiment may also be implemented in which the content of the monomer containing multiple aromatic rings in the aromatic ring-containing monomer is less than 5% by weight. A monomer containing multiple aromatic rings may not be used.

When the acrylic polymer contains the monomer containing multiple aromatic rings as a monomer component constituting the polymer, the proportion of the monomer containing multiple aromatic rings in the total monomer components (100% by weight) constituting the acrylic polymer. Although not particularly limited, it is preferably 3% by weight or more, more preferably 10% by weight or more, and still more preferably 25% by weight or more. When the ratio is 3% by weight or more, a higher refractive index tends to be easily obtained, which is preferable. From the viewpoint of making it easier to obtain a higher refractive index, the content of the monomer containing multiple aromatic rings may be, for example, more than 35% by weight, more than 50% by weight, more than 70% by weight, more than 75% by weight. It may be 85% by weight or more, 90% by weight or more, or 95% by weight or more. Further, the upper limit of the proportion of the aromatic ring-containing monomer is preferably 99% by weight or less, more preferably 98% by weight or less, from the viewpoint of achieving both a high refractive index and adhesive properties and/or optical properties in a well-balanced manner. More preferably, it is 96% by weight or less, may be 93% by weight or less, may be 90% by weight or less, may be 85% by weight or less, may be 80% by weight or less, It may be 75% by weight or less. Further, from the viewpoint of adhesive properties and/or optical properties, the content of the monomer containing multiple aromatic rings may be 70% by weight or less, 50% by weight or less, 25% by weight or less, or 15% by weight or less. It may be 5% by weight or less.

The copolymerizable monomer is not particularly limited, but from the viewpoints of suppressing clouding in high humidity environments, improving durability, compatibility with various additives such as ultraviolet absorbers, and transparency, Preferred examples include monomers having a nitrogen atom and monomers having a hydroxyl group in the molecule. That is, the acrylic polymer preferably contains a monomer having a nitrogen atom in the molecule as a structural unit. Further, the acrylic polymer preferably contains a monomer having a hydroxyl group in the molecule as a structural unit.

The monomer having a nitrogen atom in the molecule is a monomer (monomer) having at least one nitrogen atom in the molecule (in one molecule). In this specification, the above-mentioned "monomer having a nitrogen atom in the molecule" may be referred to as a "nitrogen atom-containing monomer." The nitrogen atom-containing monomer is not particularly limited, but preferred examples include cyclic nitrogen-containing monomers, (meth)acrylamides, and the like. Note that the nitrogen atom-containing monomers can 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 within the cyclic structure.

Examples of the cyclic nitrogen-containing monomer include N-vinyl cyclic amide (lactam vinyl monomer), vinyl monomer having a nitrogen-containing heterocycle, and the like.

（式（１）中、Ｒ¹は２価の有機基を示す） Examples of the N-vinyl cyclic amide include N-vinyl cyclic amide represented by the following formula (1).

(In formula (1), R ¹ represents a divalent organic group)

R ¹ in the formula (1) is a divalent organic group, preferably a divalent saturated hydrocarbon group or an unsaturated hydrocarbon group, more preferably a divalent saturated hydrocarbon group (e.g. 3 to 5 alkylene groups, etc.).

Examples of the N-vinyl cyclic amide represented by the formula (1) include N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, N-vinyl-3-morpholinone, and N-vinyl-2-caprolactam. , N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, and the like.

Examples of the vinyl monomer having a nitrogen-containing heterocycle include acrylic monomers having a nitrogen-containing heterocycle such as a morpholine ring, a piperidine ring, a pyrrolidine ring, and a piperazine ring.

The vinyl monomer having a nitrogen-containing heterocycle is not particularly limited, but includes, for example, (meth)acryloylmorpholine, N-vinylpiperazine, N-vinylpyrrole, N-vinylimidazole, N-vinylpyrazine, and N-vinylmorpholine. , N-vinylpyrazole, vinylpyridine, vinylpyrimidine, vinyloxazole, vinylisoxazole, vinylthiazole, vinylisothiazole, vinylpyridazine, (meth)acryloylpyrrolidone, (meth)acryloylpyrrolidine, (meth)acryloylpiperidine, etc. .

Among the vinyl monomers having a nitrogen-containing heterocycle, acrylic monomers having a nitrogen-containing heterocycle are preferred, and (meth)acryloylmorpholine, (meth)acryloylpyrrolidine, and (meth)acryloylpiperidine are more preferred.

Examples of the (meth)acrylamides include (meth)acrylamide, N-alkyl(meth)acrylamide, and N,N-dialkyl(meth)acrylamide. Examples of the N-alkyl (meth)acrylamide include N-ethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, Nn-butyl (meth)acrylamide, N-octyl (meth)acrylamide, and the like. . Furthermore, the N-alkyl (meth)acrylamide also includes (meth)acrylamide having an amino group such as dimethylaminoethyl (meth)acrylamide, diethylaminoethyl (meth)acrylamide, and dimethylaminopropyl (meth)acrylamide. Examples of the N,N-dialkyl (meth)acrylamide include N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N,N-dipropyl (meth)acrylamide, and N,N-diisopropyl. Examples include (meth)acrylamide, N,N-di(n-butyl)(meth)acrylamide, and N,N-di(t-butyl)(meth)acrylamide.

Further, the (meth)acrylamides include, for example, various N-hydroxyalkyl (meth)acrylamides. Examples of the N-hydroxyalkyl (meth)acrylamide include N-methylol (meth)acrylamide, N-(2-hydroxyethyl)(meth)acrylamide, N-(2-hydroxypropyl)(meth)acrylamide, N- (1-hydroxypropyl)(meth)acrylamide, N-(3-hydroxypropyl)(meth)acrylamide, N-(2-hydroxybutyl)(meth)acrylamide, N-(3-hydroxybutyl)(meth)acrylamide, Examples include N-(4-hydroxybutyl)(meth)acrylamide and N-methyl-N-2-hydroxyethyl(meth)acrylamide.

Further, the (meth)acrylamides include, for example, various N-alkoxyalkyl (meth)acrylamides. Examples of the N-alkoxyalkyl (meth)acrylamide include N-methoxymethyl (meth)acrylamide and N-butoxymethyl (meth)acrylamide.

Examples of the cyclic nitrogen-containing monomer and the nitrogen atom-containing monomer other than the (meth)acrylamides include amino group-containing monomers, cyano group-containing monomers, imide group-containing monomers, and isocyanate group-containing monomers. Examples of the amino group-containing monomer include aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, and t-butylaminoethyl (meth)acrylate. . Examples of the cyano group-containing monomer include acrylonitrile and methacrylonitrile. The imide group-containing monomers include maleimide monomers (for example, N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide, etc.), itaconimide monomers (for example, N-methylitaconimide, N- ethyl itaconimide, N-butyl itaconimide, N-octyl itaconimide, N-2-ethylhexyl itaconimide, N-lauryl itaconimide, N-cyclohexy itaconimide, etc.), succinimide monomers (e.g. N-(meth)acryloyl oxymethylene succinimide, N-(meth)acryloyl-6-oxyhexamethylene succinimide, N-(meth)acryloyl-8-oxyoctamethylene succinimide, etc.). Examples of the isocyanate group-containing monomer include 2-(meth)acryloyloxyethyl isocyanate.

Among these, the nitrogen atom-containing monomer is preferably a cyclic nitrogen-containing monomer, and more preferably N-vinyl cyclic amide. More specifically, N-vinyl-2-pyrrolidone (NVP) is particularly preferred.

When the acrylic polymer contains the nitrogen atom-containing monomer as a monomer component constituting the polymer, the proportion of the nitrogen atom-containing monomer in the total monomer components (100% by weight) constituting the acrylic polymer is: Although not particularly limited, it is preferably 1% by weight or more, more preferably 3% by weight or more, and still more preferably 5% by weight or more. It is preferable that the ratio is 1% by weight or more, since it is possible to further improve the suppression of clouding and durability in a high-humidity environment. Further, the upper limit of the proportion of the nitrogen atom-containing monomer is preferably 30% by weight or less, more preferably 25% by weight or less, from the viewpoint of obtaining an adhesive layer with appropriate flexibility and an adhesive layer with excellent transparency. % or less, more preferably 20% by weight or less.

The monomer having a hydroxyl group in the molecule is a monomer having at least one hydroxyl group in the molecule (in one molecule), and is a monomer having an unsaturated double bond such as a (meth)acryloyl group or a vinyl group. Preferred examples include those having a functional group and a hydroxyl group. However, the monomer having a hydroxyl group in the molecule does not include the nitrogen atom-containing monomer. That is, in this specification, a monomer having both a nitrogen atom and a hydroxyl group in its molecule is included in the above-mentioned "nitrogen atom-containing monomer." In this specification, the above-mentioned "monomer having a hydroxyl group in the molecule" may be referred to as a "hydroxyl group-containing monomer." Note that the hydroxyl group-containing monomers can be used alone or in combination of two or more.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, ( Hydroxyl group-containing compounds such as 6-hydroxyhexyl meth)acrylate, hydroxyoctyl (meth)acrylate, hydroxydecyl (meth)acrylate, hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl) (meth)acrylate Examples include meth)acrylic acid ester; vinyl alcohol; allyl alcohol.

Among these, the hydroxyl group-containing monomer is preferably a hydroxyl group-containing (meth)acrylic ester, more preferably 2-hydroxyethyl acrylate (HEA) or 4-hydroxybutyl acrylate (4HBA).

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% by weight) constituting the acrylic polymer is particularly limited. However, from the viewpoint of suppressing clouding in a high humidity environment and improving durability, it is preferably 0.5% by weight or more, more preferably 0.8% by weight or more, and even more preferably 1% by weight. % or more. Further, the upper limit of the proportion of the hydroxyl group-containing monomer is preferably 30% by weight or less, more preferably 30% by weight or less, from the viewpoint of obtaining an adhesive layer with appropriate flexibility and an adhesive layer with excellent transparency. It is 25% by weight or less, more preferably 15% by weight or less.

The total proportion of the nitrogen atom-containing monomer and the hydroxyl group-containing monomer in all the monomer components (100% by weight) constituting the acrylic polymer is not particularly limited, but it can be used to suppress clouding in a high humidity environment. From the viewpoint of improving durability, the content is preferably 1% by weight or more, more preferably 5% by weight or more, and still more preferably 10% by weight or more. Further, the upper limit of the total ratio is preferably 50% by weight or less, more preferably 40% by weight or less, from the viewpoint of obtaining an adhesive layer with appropriate flexibility and excellent transparency. % or less, more preferably 35% by weight or less.

Copolymerizable monomers other than the nitrogen atom-containing monomer and the hydroxyl group-containing monomer further include alicyclic structure-containing monomers. The alicyclic structure-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 an alicyclic structure. For example, an alkyl (meth)acrylate having a cycloalkyl group is included in the alicyclic structure-containing monomer. Note that the alicyclic structure-containing monomers can be used alone or in combination of two or more.

The alicyclic structure in the alicyclic structure-containing monomer is a cyclic hydrocarbon structure, and preferably has 5 or more carbon atoms, more preferably 6 to 24 carbon atoms, even more preferably 6 to 15 carbon atoms, and Particularly preferred is 6 to 10.

Examples of the alicyclic structure-containing monomer include cyclopropyl (meth)acrylate, cyclobutyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, cyclooctyl (meth)acrylate, Isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, HPMPA represented by the following formula (2), TMA-2 represented by the following formula (3), HCPA represented by the following formula (4), etc. Examples include acrylic monomers. In addition, in the following formula (4), the bonding position between the cyclohexyl ring connected by a line and the structural formula in parentheses is not particularly limited. Among these, isobornyl (meth)acrylate is preferred.

When the acrylic polymer contains the alicyclic structure-containing monomer as a monomer component constituting the polymer, the proportion of the alicyclic structure-containing monomer in the total monomer components (100% by weight) constituting the acrylic polymer. Although not particularly limited, it is preferably 10% by weight or more from the viewpoint of improving durability. Further, the upper limit of the proportion of the alicyclic structure-containing monomer is preferably 50% by weight or less, more preferably 40% by weight or less, still more preferably 30% by weight or less, from the viewpoint of obtaining an adhesive layer with appropriate flexibility. It is.

Furthermore, examples of copolymerizable monomers include polyfunctional monomers. Examples of the polyfunctional monomer include hexanediol di(meth)acrylate, butanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, and neopentyl. Glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, Examples include allyl (meth)acrylate, vinyl (meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, and urethane acrylate. Note that the polyfunctional monomers can be used alone or in combination of two or more types.

When the acrylic polymer contains the polyfunctional monomer as a monomer component constituting the polymer, the proportion of the polyfunctional monomer in the total monomer components (100% by weight) constituting the acrylic polymer is: Although not particularly limited, it is preferably 0.5% by weight or less (for example, more than 0% by weight and 0.5% by weight or less), more preferably 0.2% by weight or less (for example, more than 0% by weight and 0.5% by weight or less). 2% by weight or less).

Furthermore, examples of the copolymerizable monomer include (meth)acrylic acid alkoxyalkyl ester. The (meth)acrylic acid alkoxyalkyl ester is not particularly limited, but includes, for example, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, ( Examples include 3-methoxypropyl meth)acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, and 4-ethoxybutyl (meth)acrylate. Among these, the (meth)acrylic acid alkoxyalkyl ester is preferably an acrylic acid alkoxyalkyl ester, and more preferably 2-methoxyethyl acrylate (MEA). In addition, the said (meth)acrylic acid alkoxyalkyl ester can be used individually or in combination of 2 or more types.

When the acrylic polymer contains the (meth)acrylic acid alkoxyalkyl ester as a monomer component constituting the polymer, the ratio of the (meth)acrylic acid alkyl ester to the (meth)acrylic acid alkoxyalkyl ester is: Although not particularly limited, [former:latter] (weight ratio) preferably exceeds 100:0 and is 25:75 or less, more preferably exceeds 100:0 and is 50:50 or less.

In addition, examples of the copolymerizable monomer include carboxyl group-containing monomers, epoxy group-containing monomers, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, (meth)acrylic acid esters having aromatic hydrocarbon groups, Examples include vinyl esters, aromatic vinyl compounds, olefins or dienes, vinyl ethers, and vinyl chloride. Examples of the carboxyl group-containing monomer include (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, etc.; , itaconic anhydride and other acid anhydride group-containing monomers are also included. Examples of the epoxy group-containing monomer include glycidyl (meth)acrylate and methylglycidyl (meth)acrylate. Examples of the sulfonic acid group-containing monomer include sodium vinyl sulfonate. Examples of the (meth)acrylic ester having an aromatic hydrocarbon group include phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate. Examples of the vinyl esters include vinyl acetate and vinyl propionate. Examples of the aromatic vinyl compound include styrene and vinyltoluene. Examples of the olefins or dienes include ethylene, propylene, butadiene, isoprene, and isobutylene. Examples of the vinyl ethers include vinyl alkyl ethers.

The acrylic polymer constitutes a polymer in order to obtain an acrylic adhesive layer with excellent corrosion resistance when the adherend of the adhesive layer includes metal or metal oxide wiring such as a touch panel. It is preferable that the monomer component does not contain or substantially contains no acidic group-containing monomer, and it is particularly preferable that it does not contain or substantially contains no carboxyl group-containing monomer. Examples of the acidic group-containing monomer include carboxyl group-containing monomers, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, and the like. Specifically, the proportion of the acidic group-containing monomer in the total monomer components (100% by weight) constituting the acrylic polymer is 0.05% by weight or less (preferably 0.01% by weight or less). It can be said that it does not contain substantially.

The content of the base polymer (especially acrylic polymer) in the adhesive layer of the present invention is not particularly limited, but is 50% by weight or more (for example, 50% by weight or more based on 100% by weight of the total weight of the adhesive layer of the present invention). to 100% by weight), more preferably 80% by weight or more (for example, 80 to 100% by weight), still more preferably 90% by weight or more (for example, 90 to 100% by weight).

The base polymer such as the acrylic polymer contained in the adhesive layer of the present invention is obtained by polymerizing monomer components. This polymerization method is not particularly limited, and includes, for example, a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, a polymerization method using active energy ray irradiation (active energy ray polymerization method), and the like. Among these, the solution polymerization method and the active energy ray polymerization method are preferred from the viewpoint of transparency of the adhesive layer, cost, and the like.

Furthermore, various common solvents may be used during the polymerization of the monomer components. Examples of the solvent include esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; cyclohexane and methylcyclohexane. alicyclic hydrocarbons; organic solvents such as ketones such as methyl ethyl ketone and methyl isobutyl ketone. In addition, a solvent can be used individually or in combination of 2 or more types.

When polymerizing the monomer components, a polymerization initiator such as a thermal polymerization initiator or a photopolymerization initiator (photoinitiator) may be used depending on the type of polymerization reaction. In addition, a polymerization initiator can be used individually or in combination of 2 or more types.

The thermal polymerization initiator is not particularly limited, but includes, for example, an azo polymerization initiator, a peroxide polymerization initiator (for example, dibenzoyl peroxide, tert-butyl permaleate, etc.), a redox polymerization initiator, etc. can be mentioned. Among these, the azo polymerization initiator disclosed in JP-A No. 2002-69411 is preferred. Examples of the azo polymerization initiator include 2,2'-azobisisobutyronitrile (hereinafter sometimes referred to as "AIBN") and 2,2'-azobis-2-methylbutyronitrile (hereinafter referred to as "AIBN"). (sometimes referred to as "AMBN"), dimethyl 2,2'-azobis(2-methylpropionate), and 4,4'-azobis-4-cyanovaleric acid. Note that the thermal polymerization initiator can be used alone or in combination of two or more types.

When using the azo polymerization initiator during polymerization of the acrylic polymer, the amount of the azo polymerization initiator used is not particularly limited, but for example, 100 parts by weight of all monomer components constituting the acrylic polymer. It is preferably 0.05 part by weight or more, more preferably 0.1 part by weight or more, and preferably 0.5 part by weight or less, more preferably 0.3 part by weight. It is as follows.

The photopolymerization initiator is not particularly limited, but includes, for example, a benzoin ether photopolymerization initiator, an acetophenone photopolymerization initiator, an α-ketol photopolymerization initiator, an aromatic sulfonyl chloride photopolymerization initiator, and a photopolymerization initiator. Examples include active oxime photopolymerization initiators, benzoin photopolymerization initiators, benzyl photopolymerization initiators, benzophenone photopolymerization initiators, ketal photopolymerization initiators, thioxanthone photopolymerization initiators, and the like. Other examples include acylphosphine oxide photopolymerization initiators and titanocene photopolymerization initiators. Examples of the benzoin ether photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethan-1-one, Examples include anisole methyl ether. Examples of the acetophenone photopolymerization initiator include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenylketone, 4-phenoxydichloroacetophenone, 4-(t-butyl ) dichloroacetophenone, etc. Examples of the α-ketol photopolymerization initiator include 2-methyl-2-hydroxypropiophenone, 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one, and the like. It will be done. Examples of the aromatic sulfonyl chloride photopolymerization initiator include 2-naphthalenesulfonyl chloride. Examples of the photoactive oxime-based photopolymerization initiator include 1-phenyl-1,1-propanedione-2-(O-ethoxycarbonyl)-oxime. Examples of the benzoin-based photopolymerization initiator include benzoin. Examples of the benzyl-based photopolymerization initiator include benzyl. Examples of the benzophenone photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, and α-hydroxycyclohexylphenyl ketone. Examples of the ketal-based photopolymerization initiator include benzyl dimethyl ketal. Examples of the thioxanthone photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone. Examples of the acylphosphine oxide photopolymerization initiator include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, and the like. . As the titanocene photopolymerization initiator, for example, bis(η ⁵ -2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl ) titanium, etc. In addition, a photoinitiator can be used individually or in combination of 2 or more types.

When the photopolymerization initiator is used during the polymerization of the acrylic polymer, the amount of the photopolymerization initiator used is not particularly limited, but for example, the amount of the photopolymerization initiator is, for example, based on 100 parts by weight of all monomer components constituting the acrylic polymer. The amount is preferably 0.01 parts by weight or more, more preferably 0.1 parts by weight or more, and preferably 3 parts by weight or less, and more preferably 1.5 parts by weight or less.

(acrylic oligomer)
The adhesive layer of the present invention may contain, but is not particularly limited to, an acrylic oligomer. As the acrylic oligomer, it is preferable to use a polymer having a weight average molecular weight (Mw) smaller than that of the acrylic polymer. By using such an acrylic oligomer, the acrylic oligomer is interposed between the acrylic polymers, and the acrylic Polymer entanglement is reduced, the polymer becomes more easily deformed in response to minute strains, and the flexibility of the laminate of the present invention tends to improve.

Examples of monomers constituting the acrylic oligomer include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, and s- Butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate Alkyl(meth)acrylates, isooctyl(meth)acrylate, nonyl(meth)acrylate, isononyl(meth)acrylate, decyl(meth)acrylate, isodecyl(meth)acrylate, undecyl(meth)acrylate, dodecyl(meth)acrylate Acrylates; esters of (meth)acrylic acid and alicyclic alcohols such as cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate; phenyl (meth)acrylate, benzyl (meth)acrylate Examples include aryl (meth)acrylates such as; (meth)acrylates obtained from terpene compound derivative alcohols; Such (meth)acrylates can be used alone or in combination of two or more.

Examples of acrylic oligomers include alkyl (meth)acrylates in which the alkyl group has a branched structure such as isobutyl (meth)acrylate and t-butyl (meth)acrylate; cyclohexyl (meth)acrylate and isobornyl (meth)acrylate dicyclo Esters of (meth)acrylic acid and alicyclic alcohols such as pentanyl (meth)acrylate; esters with a cyclic structure such as aryl (meth)acrylates such as phenyl (meth)acrylate and benzyl (meth)acrylate ( It is preferable that the monomer unit contains an acrylic monomer having a relatively bulky structure, such as meth)acrylate. By providing the acrylic oligomer with such a bulky structure, the adhesiveness of the pressure-sensitive adhesive layer can be further improved. Particularly in terms of bulk, those with a cyclic structure are highly effective, and those containing multiple rings are even more effective. In addition, when using ultraviolet rays when synthesizing acrylic oligomers or creating adhesive layers, those with saturated bonds are preferable because they are less likely to inhibit polymerization, and alkyl groups with branched structures are preferable. The alkyl (meth)acrylate or ester with an alicyclic alcohol can be suitably used as the monomer constituting the acrylic oligomer.

From this point of view, suitable acrylic oligomers include, for example, copolymers of butyl acrylate (BA), methyl acrylate (MA), and acrylic acid (AA), and copolymers of cyclohexyl methacrylate (CHMA) and isobutyl methacrylate (IBMA). Copolymers, copolymers of cyclohexyl methacrylate (CHMA) and isobornyl methacrylate (IBXMA), copolymers of cyclohexyl methacrylate (CHMA) and acryloylmorpholine (ACMO), copolymers of cyclohexyl methacrylate (CHMA) and diethyl acrylamide (DEAA) Copolymer, copolymer of 1-adamantyl acrylate (ADA) and methyl methacrylate (MMA), copolymer of dicyclopentanyl methacrylate (DCPMA) and isobornyl methacrylate (IBXMA), dicyclopentanyl methacrylate (DCPMA) ), cyclohexyl methacrylate (CHMA), isobornyl methacrylate (IBXMA), isobornyl acrylate (IBXA), copolymer of cyclopentanyl methacrylate (DCPMA) and methyl methacrylate (MMA), dicyclopentanyl acrylate (DCPA) , 1-adamantyl methacrylate (ADMA), and 1-adamantyl acrylate (ADA) homopolymers.

Polymerization methods for acrylic oligomers include solution polymerization, emulsion polymerization, bulk polymerization, emulsion polymerization, polymerization by heat or active energy ray irradiation (thermal polymerization, active energy ray polymerization), etc., as with acrylic polymers. Among these, solution polymerization and active energy ray polymerization are preferred in terms of transparency, water resistance, cost, and the like. Further, the obtained acrylic oligomer may be a random copolymer, a block copolymer, a graft copolymer, or the like.

Acrylic oligomers, like acrylic polymers, can be used in solvent-type adhesive compositions and active energy ray-curable adhesive compositions. For example, as an active energy ray-curable pressure-sensitive adhesive composition, an acrylic oligomer may be further mixed with a mixture of monomer components constituting an acrylic polymer (monomer mixture) or a partial polymer thereof. When the acrylic oligomer is dissolved in a solvent, the adhesive layer can be obtained by heat-drying the adhesive composition to remove the solvent and then completing curing with active energy rays.

The weight average molecular weight (Mw) of the acrylic oligomer used in the solvent-type adhesive composition is preferably 1,000 or more, more preferably 2,000 or more, even more preferably 3,000 or more, and particularly preferably 4,000 or more. Moreover, the weight average molecular weight (Mw) of the acrylic oligomer is preferably 30,000 or less, more preferably 15,000 or less, even more preferably 10,000 or less, and particularly preferably 7,000 or less. By adjusting the weight average molecular weight (Mw) of the acrylic oligomer within the above range, for example, when used in combination with an acrylic polymer, the acrylic oligomer is interposed between the acrylic polymers, and the entanglement of the acrylic polymers is prevented. The pressure-sensitive adhesive layer tends to be more easily deformed due to minute distortions, reducing the strain applied to other layers, and suppressing cracks in each layer and peeling between the adhesive layer and other layers. be. Note that the weight average molecular weight (Mw) of the acrylic oligomer is a value measured by GPC (gel permeation chromatography) and calculated based on polystyrene conversion, similarly to the acrylic polymer.

When the adhesive composition contains an acrylic oligomer, its amount is not particularly limited, but for example, it is preferably 70 parts by weight or less, more preferably 1 to 70 parts by weight, based on 100 parts by weight of the acrylic polymer. , more preferably 2 to 50 parts by weight, still more preferably 3 to 40 parts by weight. By adjusting the blending amount of the acrylic oligomer within the above range, the acrylic oligomer is moderately interposed between the acrylic polymers, reducing entanglement of the acrylic polymers, and making the adhesive layer resistant to minute distortions. It tends to become easier to deform, reduce strain on other layers, and suppress cracking of each layer and peeling between the adhesive layer and other layers.

The adhesive layer of the present invention is not particularly limited, but preferably contains a high refractive index organic material. When the adhesive layer of the present invention contains a high refractive index organic material, it is possible to obtain an adhesive layer with a high refractive index, suppress reflection at the interface with the OLED display panel, and improve the lighting rate of light from the OLED element. ,preferable. Note that the high refractive index organic materials can be used alone or in combination of two or more.

A high refractive index organic material represents an organic material with a high refractive index. By using such a high refractive index organic material in combination with an acrylic polymer, the refractive index and adhesive properties (peel strength, flexibility, etc.) and/or optical properties (total light transmittance, haze value, etc.) can be improved. It is possible to realize a pressure-sensitive adhesive that satisfies both conditions. The organic material used as the high refractive index organic material may be a polymer or a non-polymer. Further, it may or may not have a polymerizable functional group.

The refractive index of the high refractive index organic material is not limited to a specific range because it can be set within an appropriate range in relation to the refractive index of the acrylic polymer. The refractive index of the high refractive index organic material is, for example, more than 1.50, more than 1.55, or more than 1.57, and is preferably higher than the refractive index of the acrylic polymer. From the viewpoint of increasing the refractive index of the adhesive, the refractive index of the high refractive index organic material is advantageously 1.58 or more, preferably 1.60 or more, and 1.63 or more. is more preferable, and may be 1.65 or more, 1.70 or more, or 1.75 or more. With a higher refractive index organic material, the desired refractive index can be achieved using a smaller amount of the high refractive index organic material. This is preferable from the viewpoint of suppressing deterioration of adhesive properties and optical properties. The upper limit of the refractive index of the high refractive index organic material is not particularly limited, but from the viewpoint of compatibility in the adhesive and the ease of achieving both a high refractive index and flexibility suitable for the adhesive, for example, 3.000 or less, and may be 2.500 or less, 2.000 or less, 1.950 or less, 1.900 or less, or 1.850 or less. Further, as the high refractive index organic material, one that functions as a plasticizer that imparts flexibility to the adhesive layer can also be used.

The refractive index of the high refractive index organic material and the adhesive layer is measured using an Abbe refractometer at a measurement wavelength of 589 nm and a measurement temperature of 25°C. If a manufacturer or the like provides a nominal value of the refractive index at 25° C., that nominal value can be used.

The difference between the refractive index n _b of the high refractive index organic material and the refractive index n _a of the acrylic polymer, that is, n _b - _na (hereinafter also referred to as "Δn _A "), is set to be greater than 0. Ru. Δn _A is, for example, 0.02 or more, 0.05 or more, 0.07 or more, 0.10 or more, 0.15 or more, 0.20 or more, or 0.25 or more. good. By selecting the acrylic polymer and the high refractive index organic material so that Δn _A becomes larger, the effect of improving the refractive index by using the high refractive index organic material tends to be enhanced. Further, from the viewpoint of compatibility of the high refractive index organic material in the adhesive layer, Δn _A may be, for example, 0.70 or less, 0.60 or less, 0.50 or less, 0.40 or less. It may be less than or equal to 0.35.

The difference between the refractive index n _b of the high refractive index organic material and the refractive index n _T of the adhesive layer containing the high refractive index organic material, that is, n _b - n _T (hereinafter also referred to as "Δn _B ") is , may be set to be greater than 0. In some embodiments, Δn _B is, for example, 0.02 or more, 0.05 or more, 0.07 or more, 0.10 or more, 0.15 or more, 0.20 or more. Alternatively, it may be 0.25 or more. By selecting the composition of the adhesive layer and the high refractive index organic material so that Δn _B becomes larger, the effect of improving the refractive index by using the high refractive index organic material tends to be enhanced. Further, from the viewpoint of compatibility within the adhesive layer, transparency of the adhesive layer, etc., in some embodiments, Δn _B may be, for example, 0.70 or less, 0.60 or less, or 0. It may be .50 or less, 0.40 or less, or 0.35 or less.

The molecular weight of the organic material used as the high refractive index organic material is not particularly limited and can be selected depending on the purpose. From the viewpoint of achieving a good balance between the effect of increasing the refractive index and other properties (for example, flexibility suitable for adhesives, optical properties such as haze), the molecular weight of the high refractive index organic material is approximately less than 10,000. It is suitable that it is less than 5,000, more preferably less than 3,000 (for example, less than 1,000), it may be less than 800, it may be less than 600, it may be less than 500, and it may be less than 400. It may be advantageous that the molecular weight of the high refractive index organic material is not too large from the viewpoint of improving compatibility within the adhesive layer. Further, the molecular weight of the high refractive index organic material may be, for example, 130 or more, or 150 or more. From the viewpoint of increasing the refractive index of the high refractive index organic material, the molecular weight of the high refractive index organic material is preferably 170 or more, more preferably 200 or more, may be 230 or more, or may be 250 or more. , 270 or more, 500 or more, 1000 or more, 2000 or more. A polymer having a molecular weight of about 1,000 to 10,000 (for example, 1,000 or more and less than 5,000) can be used as the high refractive index organic material.
Regarding the molecular weight of high refractive index organic materials, for non-polymers or polymers with a low degree of polymerization (e.g. dimer to pentamer), the molecular weight calculated based on the chemical structure or matrix-assisted laser desorption ionization flight Measured values using time-based mass spectrometry (MALDI-TOF-MS) can be used. When the high refractive index organic material is a polymer with a higher degree of polymerization, the weight average molecular weight (Mw) based on GPC performed under appropriate conditions can be used. If a nominal value of molecular weight is provided by a manufacturer, etc., that nominal value can be used.

Examples of organic materials that can be selected as high refractive index organic materials include organic compounds having aromatic rings, organic compounds having heterocycles (which may be aromatic rings or non-aromatic heterocycles), etc. but not limited to.

The aromatic ring possessed by the organic compound having an aromatic ring (hereinafter also referred to as "aromatic ring-containing compound") used as a high refractive index organic material is similar to the aromatic ring possessed by the compound used as the aromatic ring-containing monomer. can be selected from.

The aromatic ring may have one or more substituents on the ring-constituting atoms, or may have no substituents. When having a substituent, the substituent includes an alkyl group, an alkoxy group, an aryloxy group, a hydroxyl group, a halogen atom (fluorine atom, chlorine atom, bromine atom, etc.), a hydroxyalkyl group, a hydroxyalkyloxy group, a glycidyloxy group. Examples include, but are not limited to. In a substituent containing carbon atoms, the number of carbon atoms contained in the substituent is, for example, 1 to 10, advantageously 1 to 6, preferably 1 to 4, more preferably 1 to 3. and can be, for example, 1 or 2. The aromatic ring has no substituent on the ring constituent atoms or has one or more substituents selected from the group consisting of an alkyl group, an alkoxy group, and a halogen atom (for example, a bromine atom). obtain.

Examples of aromatic ring-containing compounds that can be used as high refractive index organic materials include: Compounds that can be used as aromatic ring-containing monomers; Oligomers containing as monomer units compounds that can be used as aromatic ring-containing monomers; Aromatic ring-containing monomers From the compounds that can be used as a hydrogen atom or an ethylene Compounds whose structure is replaced with a group that does not have a sexually unsaturated group (for example, a hydroxyl group, an amino group, a halogen atom, an alkyl group, an alkoxy group, a hydroxyalkyl group, a hydroxyalkyloxy group, a glycidyloxy group, etc.); etc. However, it is not limited to these. Non-limiting examples of aromatic ring-containing compounds that can be used as high refractive index organic materials include benzyl acrylate, m-phenoxybenzyl acrylate, 2-(o-phenylphenoxy)ethyl acrylate, phenoxyethyl acrylate, phenoxydiethylene glycol acrylate. , phenoxypolyethylene glycol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, monomers having a fluorene structure mentioned above, monomers having a dinaphthothiophene structure, monomers having a dibenzothiophene structure, and other aromatic ring-containing monomers; 3-phenoxybenzyl alcohol , dinaphthothiophene and its derivatives (for example, a structure in which one or more substituents selected from a hydroxy group, methanol group, diethanol group, glycidyl group, etc. are bonded to a dinaphthothiophene ring) aromatic ring-containing compounds having no ethylenically unsaturated group, such as compounds such as Further, the aromatic ring-containing compound is an oligomer (preferably an oligomer having a molecular weight of about 5,000 or less, more preferably about 1,000 or less; for example, a low polymer of about 2 to 5 mer) containing such an aromatic ring-containing monomer as a monomer unit. ). The oligomers include, for example: homopolymers of aromatic ring-containing monomers; copolymers of one or more aromatic ring-containing monomers; copolymers of one or more aromatic ring-containing monomers and other monomers. It can be a combination; etc. As the other monomer, one or more monomers having no aromatic ring may be used.

In some embodiments, the high refractive index organic material is an organic compound having two or more aromatic rings in one molecule (hereinafter referred to as "compound containing multiple aromatic rings") because it is easy to obtain a high refractive index effect. ) can be preferably adopted. The compound containing multiple aromatic rings may or may not have a polymerizable functional group such as an ethylenically unsaturated group. Further, the compound containing multiple aromatic rings may be a polymer or a non-polymer. Further, the polymer is an oligomer (preferably an oligomer with a molecular weight of about 5000 or less, more preferably about 1000 or less; for example, a low polymer of about 2 to 5 molecules) containing a monomer containing multiple aromatic rings as a monomer unit. obtain. The oligomer may be, for example: a homopolymer of a monomer containing a plurality of aromatic rings; a copolymer of one or more monomers containing a plurality of aromatic rings; a copolymer of one or more monomers containing a plurality of aromatic rings and another monomer; copolymers; etc. The other monomer may be an aromatic ring-containing monomer that does not correspond to a monomer containing multiple aromatic rings, a monomer having no aromatic ring, or a combination thereof.

Non-limiting examples of compounds containing multiple aromatic rings include compounds having a structure in which two or more non-fused aromatic rings are bonded via a linking group; Examples include a compound having a chemically bonded structure (without intervening), a compound having a fused aromatic ring structure, a compound having a fluorene structure, a compound having a dinaphthothiophene structure, a compound having a dibenzothiophene structure, and the like. The compound containing multiple aromatic rings can be used alone or in combination of two or more.

Specific examples of the compound having a fluorene structure include the above-mentioned monomer having a fluorene structure and oligomers that are homopolymers or copolymers of such monomers, as well as 9,9-bis(4-hydroxyphenyl)fluorene ( Refractive index: 1.68), 9,9-bis(4-aminophenyl)fluorene (Refractive index: 1.73), 9,9-bis(4-hydroxy-3-methylphenyl)fluorene (Refractive index: 1 .68), 9,9-bisphenylfluorene and its derivatives, such as 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene (refractive index: 1.65).

Specific examples of the compound having the dinaphthothiophene structure include the above-mentioned monomer having the dinaphthothiophene structure and oligomers that are homopolymers or copolymers of such monomers, as well as dinaphthothiophene (refractive index: 1. 808); Hydroxyalkyldinaphthothiophenes such as 6-hydroxymethyldinaphthothiophene (refractive index: 1.766); Dihydroxydinaphthothiophenes such as 2,12-dihydroxydinaphthothiophene (refractive index: 1.750); 2 , 12-dihydroxyalkyloxydinaphthothiophene (refractive index: 1.677); diglycidyloxydinaphthothiophene such as 2,12-diglycidyloxydinaphthothiophene (refractive index: 1.723); naphthothiophene; dinaphthothiophene having two or more ethylenically unsaturated groups, such as 2,12-diallyloxydinaphthothiophene (abbreviation: 2,12-DAODNT, refractive index 1.729); Examples include derivatives thereof.

Specific examples of the compound having the dibenzothiophene structure include the above-mentioned monomer having the dibenzothiophene structure and oligomers that are homopolymers or copolymers of such monomers, as well as dibenzothiophene (refractive index: 1.607), Examples include 4-dimethyldibenzothiophene (refractive index: 1.617), 4,6-dimethyldibenzothiophene (refractive index: 1.617), and the like.

Examples of organic compounds having a heterocycle (hereinafter also referred to as heterocycle-containing organic compounds) that can be selected as high refractive index organic materials include thioepoxy compounds, compounds having a triazine ring, and the like. Examples of thioepoxy compounds include bis(2,3-epithiopropyl) disulfide and its polymer (refractive index 1.74) described in Japanese Patent No. 3712653. Examples of compounds having a triazine ring include compounds having at least one (eg, 3 to 40, preferably 5 to 20) triazine rings in one molecule. In addition, since the triazine ring has aromaticity, compounds having a triazine ring are also included in the concept of the aromatic ring-containing compound, and compounds having multiple triazine rings are also included in the concept of the compound containing multiple aromatic rings. be done.

As the high refractive index organic material, a compound having no ethylenically unsaturated group can be preferably employed. Thereby, deterioration of the adhesive composition due to heat or light (decrease in leveling properties due to progress of gelation or increase in viscosity) can be suppressed, and storage stability can be improved. Adopting a high refractive index organic material that does not have ethylenically unsaturated groups means that in an adhesive film having an adhesive layer containing the high refractive index organic material or a laminate containing the adhesive film, ethylenically unsaturated It is also preferable from the viewpoint of suppressing dimensional changes, deformations (warpage, waving, etc.), optical distortion, etc. caused by group reactions.

In embodiments in which oligomers are used as the high refractive index organic material, the oligomers can be obtained by polymerizing the corresponding monomer components by a known method. When the oligomer is produced by radical polymerization, polymerization can be carried out by appropriately adding a polymerization initiator, a chain transfer agent, an emulsifier, etc. used in radical polymerization to the monomer component. The polymerization initiator, chain transfer agent, emulsifier, etc. used in the radical polymerization are not particularly limited, and can be appropriately selected and used. The weight average molecular weight of the oligomer can be controlled by the amounts of the polymerization initiator and chain transfer agent used and the reaction conditions, and the amounts used are adjusted as appropriate depending on the types of these.
Examples of the chain transfer agent include lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, α-thioglycerol, thioglycolic acid, 2-ethylhexyl thioglycolate, 2,3-dimercapto-1-propanol, and the like. It will be done. One type of chain transfer agent may be used alone, or two or more types may be used in combination. The amount of the chain transfer agent used can be determined depending on the composition of the monomer components used in oligomer synthesis, the type of chain transfer agent, etc. so as to obtain an oligomer with a desired weight average molecular weight. In some embodiments, the amount of chain transfer agent used is approximately 15 parts by weight or less, and may be 10 parts by weight or less, and may be 5 parts by weight or less, based on 100 parts by weight of the total amount of monomers used to synthesize the oligomer. It may be less than that. The lower limit of the amount of the chain transfer agent to be used with respect to 100 parts by weight of the total amount of monomers used in the synthesis of the oligomer is not particularly limited, but may be, for example, 0.01 parts by weight or more, 0.1 parts by weight or more, and 0.01 parts by weight or more. The amount may be 5 parts by weight or more, or 1 part by weight or more.

The amount of the high refractive index organic material used (if multiple types of compounds are used, the total amount thereof) based on 100 parts by weight of the acrylic polymer is not particularly limited as long as it exceeds 0 parts by weight, and is set depending on the purpose. be able to. The amount of the high refractive index organic material used per 100 parts by weight of the acrylic polymer can be, for example, 80 parts by weight or less, achieving a good balance between increasing the refractive index of the adhesive and suppressing deterioration of adhesive properties and optical properties. From this point of view, it is advantageous to use 60 parts by weight or less, and preferably 45 parts by weight or less. From the viewpoint of placing more emphasis on adhesive properties and optical properties, the amount of the high refractive index organic material used relative to 100 parts by weight of the acrylic polymer may be, for example, 30 parts by weight or less, 20 parts by weight or less, 15 parts by weight or less. The amount may be 10 parts by weight or less. In addition, from the viewpoint of increasing the refractive index of the adhesive, the amount of the high refractive index organic material used per 100 parts by weight of the acrylic polymer can be, for example, 1 part by weight or more, and preferably 3 parts by weight or more. The amount is preferably 5 parts by weight or more, 7 parts by weight or more, 10 parts by weight or more, 15 parts by weight or more, and 20 parts by weight or more.

The adhesive layer of the present invention may contain an ultraviolet absorber (UVA). When the adhesive layer of the present invention 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 with excellent weather resistance can be obtained. Note that the ultraviolet absorbers can be used alone or in combination of two or more.

The UV absorbers are not particularly limited, but include, for example, benzotriazole UV absorbers, hydroxyphenyltriazine UV absorbers, benzophenone UV absorbers, salicylic acid ester UV absorbers, cyanoacrylate UV absorbers, and Examples include benzophenone ultraviolet absorbers.

Examples of benzotriazole-based ultraviolet absorbers (benzotriazole-based compounds) include 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole (trade name "TINUVIN PS", manufactured by BASF), benzene Ester compound of propanoic acid and 3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy (C7-9 side chain and straight chain alkyl) (trade name "TINUVIN 384") -2'', manufactured by BASF), octyl 3-[3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazol-2-yl)phenyl]propionate and 2-ethylhexyl-3-[ A mixture of 3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazol-2yl)phenyl]propionate (trade name "TINUVIN 109", manufactured by BASF), 2-(2H-benzotriazole) 2-(2H-benzotriazol-2-yl)-6- (1-Methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (trade name "TINUVIN 928", manufactured by BASF), methyl 3-(3-(2H-benzotriazole) -2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate/polyethylene glycol 300 reaction product (trade name "TINUVIN 1130", manufactured by BASF), 2-(2H-benzotriazol-2-yl) )-p-cresol (trade name "TINUVIN P", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (trade name "TINUVIN 234", manufactured by BASF), 2-[5-chloro-2H-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol (trade name "TINUVIN 326", manufactured by BASF) ), 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (trade name "TINUVIN 328", manufactured by BASF), 2-(2H-benzotriazol-2-yl) -4-(1,1,3,3-tetramethylbutyl)phenol (trade name "TINUVIN 329", manufactured by BASF), 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)- 4-(1,1,3,3-tetramethylbutyl)phenol] (trade name "TINUVIN 360", manufactured by BASF), methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert - Reaction product of butyl-4-hydroxyphenyl) propionate and polyethylene glycol 300 (trade name "TINUVIN 213", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-6-dodecyl-4- Methylphenol (trade name "TINUVIN 571", manufactured by BASF), 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimido-methyl)-5-methylphenyl]benzotriazole (trade name " Sumisorb 250'', manufactured by Sumitomo Chemical Co., Ltd.), 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-tert-octylphenol] (trade name: ``Adekastab LA-31'', manufactured by Sumitomo Chemical Co., Ltd.) ) manufactured by ADEKA).

Examples of hydroxyphenyltriazine-based ultraviolet absorbers (hydroxyphenyltriazine-based compounds) include 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5 - Reaction product of hydroxyphenyl and [(C10-C16 (mainly C12-C13) alkyloxy)methyl]oxirane (trade name "TINUVIN 400", manufactured by BASF), 2-[4,6-bis(2, 4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-[3-(dodecyloxy)-2-hydroxypropoxy]phenol), 2-(2,4-dihydroxyphenyl)-4, Reaction product of 6-bis-(2,4-dimethylphenyl)-1,3,5-triazine and (2-ethylhexyl)-glycidic acid ester (trade name "TINUVIN 405", manufactured by BASF), 2,4 -bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-dibutoxyphenyl)-1,3,5-triazine (trade name "TINUVIN 460", manufactured by BASF), 2-(4, 6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]-phenol (trade name "TINUVIN 1577", manufactured by BASF), 2-(4,6-diphenyl-1 , 3,5-triazin-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]-phenol (trade name "ADEKA STAB LA-46", manufactured by ADEKA Co., Ltd.), 2-(2 -Hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine (trade name "TINUVIN 479", manufactured by BASF), etc. It will be done. Other examples include a compound represented by the following formula (5) (trade name "TINUVIN 477", manufactured by BASF).

Examples of benzophenone ultraviolet absorbers (benzophenone compounds) and oxybenzophenone ultraviolet absorbers (oxybenzophenone compounds) include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, and 2-hydroxy-4- Methoxybenzophenone-5-sulfonic acid (anhydride and trihydrate), 2-hydroxy-4-octyloxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 4-benzyloxy-2-hydroxybenzophenone, 2,2'- Dihydroxy-4-methoxybenzophenone (trade name "KEMISORB 111", manufactured by Chemipro Kasei Co., Ltd.), 2,2',4,4'-tetrahydroxybenzophenone (trade name "SEESORB 106", manufactured by Cipro Kasei Co., Ltd.) , 2,2'-dihydroxy-4,4'-dimethoxybenzophenone and the like.

Examples of salicylic acid ester ultraviolet absorbers (salicylic acid ester compounds) include phenyl 2-acryloyloxybenzoate, phenyl 2-acryloyloxy-3-methylbenzoate, phenyl 2-acryloyloxy-4-methylbenzoate, and phenyl 2-acryloyloxybenzoate. Acryloyloxy-5-methylbenzoate, phenyl 2-acryloyloxy-3-methoxybenzoate, phenyl 2-hydroxybenzoate, phenyl 2-hydroxy-3-methylbenzoate, phenyl 2-hydroxy-4-methylbenzoate, phenyl 2-hydroxy- 5-methylbenzoate, phenyl 2-hydroxy-3-methoxybenzoate, 2,4-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate (trade name: "TINUVIN 120", manufactured by BASF) ), etc.

Examples of the cyanoacrylate ultraviolet absorber (cyanoacrylate compound) include alkyl 2-cyanoacrylate, cycloalkyl 2-cyanoacrylate, alkoxyalkyl 2-cyanoacrylate, alkenyl 2-cyanoacrylate, alkynyl 2-cyanoacrylate, and the like. Can be mentioned.

As the ultraviolet absorber, benzotriazole-based ultraviolet absorbers are selected from the viewpoints of high ultraviolet absorption, excellent optical properties, ease of obtaining an adhesive layer with high transparency, and excellent photostability. At least one type of UV absorber selected from the group consisting of UV absorbers, benzophenone UV absorbers, and hydroxyphenyltriazine UV absorbers is preferred, and benzotriazole UV absorbers and benzophenone UV absorbers are more preferred. Particularly preferred are benzotriazole ultraviolet absorbers in which a group having 6 or more carbon atoms and a phenyl group having a hydroxyl group as a substituent are bonded to the nitrogen atom constituting the benzotriazole ring. Furthermore, from the viewpoint of preventing deterioration in appearance due to precipitation of the ultraviolet absorber, it is preferable to use a liquid ultraviolet absorber or two or more types of ultraviolet absorbers.

Further, in order to obtain higher ultraviolet absorbency, the ultraviolet absorber preferably has an absorbance A determined below of 0.5 or less.
Absorbance A: Absorbance measured by applying light with a wavelength of 400 nm to a 0.08% toluene solution of the ultraviolet absorber.

When the adhesive layer of the present invention contains an ultraviolet absorber, the content of the ultraviolet absorber in the adhesive layer of the present invention (particularly the acrylic adhesive layer) is not particularly limited, but the content of the ultraviolet absorber in the adhesive layer of the present invention is not particularly limited. From the viewpoint of suppressing the deterioration of OLED elements due to ultraviolet rays and obtaining an OLED display device with excellent weather resistance, the amount is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight, based on 100 parts by weight of the acrylic polymer. It is at least 0.1 part by weight, more preferably at least 0.1 part by weight. In addition, the upper limit of the content of the ultraviolet absorber is set at the point of suppressing the yellowing phenomenon of the adhesive due to the addition of the ultraviolet absorber and obtaining excellent optical properties, high transparency, and excellent appearance characteristics. More preferably, the amount is 20 parts by weight or less, more preferably 10 parts by weight or less, and even more preferably 8 parts by weight or less, based on 100 parts by weight of the acrylic polymer.

In place of the ultraviolet absorber or in combination with the ultraviolet absorber, a dye compound having a maximum absorption wavelength in the absorption spectrum in a wavelength range of 380 to 430 nm may be contained. The dye compound can also suppress deterioration of OLED elements and high refractive index components caused by ultraviolet light.

The dye compounds may be used alone or in combination of two or more. When only the dye compound is used, the total content of the dye compound is preferably 0.1 to 20 parts by weight based on 100 parts by weight of the base polymer (eg, acrylic polymer), and 0.1 to 20 parts by weight. It is preferably 1 to 10 parts by weight, preferably 0.1 to 5 parts by weight, and more preferably 0.5 to 3 parts by weight. By adjusting the amount of the dye compound added within the above range, it is possible to sufficiently absorb light in a region that does not affect the light emission of the OLED element, and by using the adhesive layer formed from the adhesive composition, the OLED This is preferable because deterioration of the element and deterioration of the high refractive index component can be suppressed.

Although either the ultraviolet absorber or the dye compound can be used, it is preferable to use the ultraviolet absorber and the dye compound together. For example, although the ultraviolet absorber can absorb light with a wavelength of 380 nm, it cannot absorb enough light in a wavelength region (380 nm to 430 nm) shorter than the light emitting region of the OLED element (longer wavelength than 430 nm). The transmitted light may cause deterioration. The dye compound can suppress the transmission of light having a wavelength shorter than 430 nm (380 nm to 430 nm) than the emission region of the OLED element (wavelength longer than 430 nm), and the ultraviolet absorber and the dye compound are used together. Thereby, sufficient visible light transmittance in the light emitting region of the OLED element can be ensured.

In the present invention, by using such a dye compound and an ultraviolet absorber in combination, it is possible to sufficiently absorb light in a region (wavelength 380 nm to 430 nm) that does not affect the light emission of the OLED element, and The light emitting region (longer wavelength side than 430 nm) can be sufficiently transmitted, and as a result, deterioration of the OLED element due to external light and deterioration of the high refractive index component can be suppressed at the same time. When the ultraviolet absorber and the dye compound are used together, the ultraviolet absorber is preferably 0.1 to 10 parts by weight based on 100 parts by weight of the base polymer (for example, acrylic polymer), It is preferably 0.1 to 5 parts by weight, more preferably 0.5 to 3 parts by weight. The amount of the dye compound is preferably about 0.1 to 10 parts by weight, more preferably about 0.1 to 5 parts by weight, based on 100 parts by weight of the base polymer (for example, acrylic polymer). More preferably, it is 0.5 to 3 parts by weight.

The dye compound is not particularly limited as long as it has a maximum absorption wavelength in the absorption spectrum in a wavelength range of 380 to 430 nm. Note that the term "maximum absorption wavelength" refers to the absorption maximum wavelength that exhibits the maximum absorbance among a plurality of absorption maximums in the spectral absorption spectrum in the wavelength region of 300 to 460 nm.

It is more preferable that the maximum absorption wavelength of the absorption spectrum of the dye compound exists in a wavelength range of 380 to 420 nm. Further, the dye compound is not particularly limited as long as it has the wavelength characteristics described above, but it is preferably a material that does not have fluorescence or phosphorescence performance (photoluminescence) and does not inhibit 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 dye compound, commercially available compounds can be suitably used. Specifically, as the indole compound, BONASORB UA3911 (trade name, maximum absorption wavelength of absorption spectrum: 398 nm, manufactured by Orient Chemical Industry Co., Ltd.), and as the cinnamic acid compound, SOM-5-0106 (trade name) was used. , maximum absorption wavelength of absorption spectrum: 416 nm, manufactured by Orient Chemical Industry Co., Ltd.), FDB-001 (trade name, maximum absorption wavelength of absorption spectrum: 420 nm, manufactured by Yamada Chemical Industry Co., Ltd.) as a porphyrin compound, cyanine As a system compound, merocyanine compound (trade name: FDB-009, maximum absorption wavelength of absorption spectrum: 394 nm, manufactured by Yamada Chemical Industry Co., Ltd.), polymethine compound (trade name: DAA-247, maximum absorption wavelength of absorption spectrum: 389 nm) , manufactured by Yamada Chemical Industry Co., Ltd.). Among these, cyanine compounds are preferred, and polymethine compounds are particularly preferred, from the viewpoints of suppressing crosslinking inhibition and optical reliability.

The adhesive layer of the present invention may contain a light stabilizer. When the adhesive layer of the present invention contains a light stabilizer, it is particularly preferable to contain the light stabilizer together with the ultraviolet absorber. Since the light stabilizer can capture radicals generated by photo-oxidation, it can improve the resistance of the adhesive layer to light (particularly ultraviolet light). In addition, a light stabilizer can be used individually or in combination of 2 or more types.

The light stabilizer is not particularly limited, but includes, for example, phenolic light stabilizers (phenol compounds), phosphorus light stabilizers (phosphorus compounds), thioether light stabilizers (thioether compounds), and amine light stabilizers. Examples include stabilizers (amine compounds) (particularly hindered amine stabilizers (hindered amine compounds)).

Examples of the phenolic light stabilizer (phenolic compound) include 2,6-di-tertiary butyl-4-methylphenol, 4-hydroxymethyl-2,6-di-tertiary butylphenol, 2, 6-di-tert-butyl-4-ethylphenol, butylated hydroxyanisole, n-octadecyl 3-(4-hydroxy-3,5-di-tert-butylphenyl) propionate, distearyl (4-hydroxy- 3-methyl-5-tert-butyl)benzyl malonate, tocopherol, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), tertiary butylphenol), 4,4'-methylenebis(2,6-di-tertiary butylphenol), 4,4'-butylidenebis(6-tertiary butyl-m-cresol), 4,4'-thiobis( 6-tert-butyl-m-cresol), styrenated phenol, N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyhydrocinnamide, bis(3,5-di -Tertiary butyl-4-hydroxybenzylphosphonic acid ethyl ester) calcium, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-trimethyl -2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxy Methyl]methane, 1,6-hexanediol-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,2'-methylenebis(4-methyl-6-cyclohexylphenol) ), 2,2'-methylenebis[6-(1-methylcyclohexyl)-p-cresol], 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanur Acid, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanuric acid, triethylene glycol-bis[3-(3-tert-butyl-4-hydroxy-5 -methylphenyl)propionate], 2,2'-oxamidobis[ethyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 6-(4-hydroxy-3,5-di- tert-butylanilino)-2,4-dioctylthio-1,3,5-triazine, bis[2-tert-butyl-4-methyl-6-(2-hydroxy-3-tert-butyl-5- methylbenzyl)phenyl]terephthalate, 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4 , 8,10-tetraoxaspiro[5.5]undecane, 3,9-bis{2-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxy]-1,1 -dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane and the like.

Examples of phosphorus-based light stabilizers (phosphorus-based compounds) include trisnonylphenyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tris[2-tert-butyl-4-( 3-tertiary butyl-4-hydroxy-5-methylphenylthio)-5-methylphenyl] phosphite, tridecyl phosphite, octyldiphenyl phosphite, di(decyl) monophenyl phosphite, di(tridecyl) penta Erythritol diphosphite, distearyl pentaerythritol diphosphite, di(nonylphenyl) pentaerythritol diphosphite, bis(2,4-di-tertiary butylphenyl) pentaerythritol diphosphite, bis(2,6- Di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, bis(2,4,6-tri-tert-butylphenyl) pentaerythritol diphosphite, tetra(tridecyl)isopropylidene diphenol diphosphite phyto, tetra(tridecyl)-4,4'-n-butylidenebis(2-tert-butyl-5-methylphenol) diphosphite, hexa(tridecyl)-1,1,3-tris(2-methyl-4-hydroxy) -5-tertiary butylphenyl)butane triphosphite, tetrakis(2,4-di-tertiary butylphenyl)biphenylene diphosphonite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene- 10-oxide, tris(2-[(2,4,8,10-tetrakis-tert-butyldibenzo[d,f][1,3,2]dioxaphosphepin-6-yl)oxy]ethyl ) amines, etc.

Examples of thioether light stabilizers (thioether compounds) include dialkylthiodipropionate compounds such as dilauryl thiodipropionate, dimyristyl, and distearyl; polyol β such as tetrakis[methylene(3-dodecylthio)propionate]methane; -Alkylmercaptopropionic acid ester compounds and the like.

As the amine light stabilizer (amine compound), for example, a polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidine ethanol (trade name "TINUVIN 622", BASF ), a polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol and N,N',N'',N'''-tetrakis-(4, 6-bis-(butyl-(N-methyl-2,2,6,6-tetramethylpiperidin-4-yl)amino)-triazin-2-yl)-4,7-diazadecane-1,10-diamine and (trade name "TINUVIN 119", manufactured by BASF), dibutylamine/1,3-triazine/N,N'-bis(2,2,6,6-tetramethyl-4- Polycondensate of piperidyl-1,6-hexamethylenediamine and N-(2,2,6,6-tetramethyl-4-piperidyl)butylamine (trade name "TINUVIN 2020", manufactured by BASF), poly[{6 -(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2-4-diyl}{2,2,6,6-tetramethyl-4-piperidyl}imino]hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl)imino} (trade name "TINUVIN 944", manufactured by BASF), bis(1,2,2,6,6-pentamethyl-4-piperidyl) Sebacate and a mixture of methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate (trade name "TINUVIN 765", manufactured by BASF), bis(2,2,6,6-tetramethyl-4- piperidyl) sebacate (trade name "TINUVIN 770", manufactured by BASF), decanedioic acid bis(2,2,6,6-tetramethyl-1-(octyloxy)-4-piperidinyl) ester, 1,1-dimethyl Reaction product of ethyl hydroperoxide and octane (trade name "TINUVIN 123", manufactured by BASF), bis(1,2,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis(1, 1-dimethylethyl)-4-hydroxyphenyl]methyl]butyl malonate (trade name "TINUVIN 144", manufactured by BASF), cyclohexane and N-butyl peroxide 2,2,6,6-tetramethyl-4-piperidine Reaction product of amine-2,4,6-trichloro-1,3,5-triazine and 2-aminoethanol (trade name "TINUVIN 152", manufactured by BASF), bis(1,2, Mixture of 2,6,6-pentamethyl-4-piperidyl) sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate (trade name "TINUVIN 292", manufactured by BASF), 1,2 , 3,4-butanetetracarboxylic acid and 1,2,2,6,6-pentamethyl-4-piperidinol and 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8, Examples include a mixed ester with 10-tetraoxaspiro[5.5]undecane (trade name "ADEKASTAB LA-63P", manufactured by ADEKA Co., Ltd.). As the amine stabilizer, hindered amine stabilizers are particularly preferred.

When the adhesive layer of the present invention contains a light stabilizer, the content of the light stabilizer in the adhesive layer of the present invention (particularly the acrylic adhesive layer) is not particularly limited, but the content of the light stabilizer is not particularly limited. In order to facilitate development, the amount is preferably 0.1 part by weight or more, more preferably 0.2 part by weight or more, based on 100 parts by weight of the acrylic polymer. In addition, the upper limit of the content is 5 parts by weight or less based on 100 parts by weight of the acrylic polymer, from the viewpoint of preventing coloration from occurring due to the light stabilizer itself, making it easy to obtain high transparency, and from the viewpoint of optical properties. The amount is preferably 3 parts by weight or less, and more preferably 3 parts by weight or less.

Although not particularly limited, a crosslinking agent may be used in forming the adhesive layer of the present invention. For example, the gel fraction can be controlled by crosslinking the acrylic polymer in the acrylic adhesive layer. In addition, a crosslinking agent can be used individually or in combination of 2 or more types.

The crosslinking agent is not particularly limited, but includes, for example, isocyanate crosslinking agents, epoxy crosslinking agents, melamine crosslinking agents, peroxide crosslinking agents, urea crosslinking agents, metal alkoxide crosslinking agents, and metal chelate crosslinking agents. agent, metal salt type crosslinking agent, carbodiimide type crosslinking agent, oxazoline type crosslinking agent, aziridine type crosslinking agent, amine type crosslinking agent and the like. Among these, isocyanate-based crosslinking agents and epoxy-based crosslinking agents are preferred, and isocyanate-based crosslinking agents are more preferred.

Examples of the isocyanate crosslinking agent (polyfunctional isocyanate compound) include lower aliphatic polyisocyanates such as 1,2-ethylene diisocyanate, 1,4-butylene diisocyanate, and 1,6-hexamethylene diisocyanate; cyclopentylene diisocyanate; , cyclohexylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, and other alicyclic polyisocyanates; 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate and aromatic polyisocyanates such as xylylene diisocyanate. In addition, examples of the isocyanate-based crosslinking agent include trimethylolpropane/tolylene diisocyanate adduct (product name "Coronate L", manufactured by Nippon Polyurethane Industries, Ltd.), trimethylolpropane/hexamethylene diisocyanate adduct (product name Commercially available products such as "Coronate HL" (manufactured by Nippon Polyurethane Industries, Ltd.) and trimethylolpropane/xylylene diisocyanate adduct (trade name "Takenate D-110N", manufactured by Mitsui Chemicals, Ltd.) can also be mentioned.

Examples of the epoxy crosslinking agent (polyfunctional epoxy compound) include N,N,N',N'-tetraglycidyl-m-xylene diamine, diglycidylaniline, 1,3-bis(N,N-diglycidyl (aminomethyl) cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether , glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl-tris(2) -hydroxyethyl) isocyanurate, resorcin diglycidyl ether, bisphenol-S-diglycidyl ether, and epoxy resins having two or more epoxy groups in the molecule. Examples of the epoxy crosslinking agent include commercially available products such as the trade name "Tetrad C" (manufactured by Mitsubishi Gas Chemical Co., Ltd.).

When a crosslinking agent is used to form the adhesive layer of the present invention, the amount of the crosslinking agent used is not particularly limited, but from the viewpoint of obtaining sufficient adhesion reliability, it is 0.00 parts by weight based on 100 parts by weight of the base polymer. It is preferably at least 0.001 part by weight, more preferably at least 0.01 part by weight. Further, the upper limit of the amount used is preferably 10 parts by weight or less, more preferably 10 parts by weight or less based on 100 parts by weight of the base polymer, from the viewpoint of obtaining appropriate flexibility in the adhesive layer and improving adhesive strength. is 5 parts by weight or less.

The adhesive layer (especially the acrylic adhesive layer) of the present invention contains a silane coupling agent in order to improve the adhesive reliability under humid conditions, especially to improve the adhesive reliability to glass. You can. Note that the silane coupling agents can be used alone or in combination of two or more. When the pressure-sensitive adhesive layer contains a silane coupling agent, the adhesiveness under humid conditions, especially the adhesiveness to glass, can be improved.

The silane coupling agent is not particularly limited, but examples thereof include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and N-phenyl-aminopropyltrimethoxysilane. Examples include methoxysilane. Furthermore, examples of the silane coupling agent include commercially available products such as the trade name "KBM-403" (manufactured by Shin-Etsu Chemical Co., Ltd.). Among these, γ-glycidoxypropyltrimethoxysilane is preferred as the silane coupling agent.

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

The adhesive layer of the present invention may further contain a crosslinking accelerator, tackifying resin (rosin derivative, polyterpene resin, petroleum resin, oil-soluble phenol, etc.), anti-aging agent, filler, coloring agent (pigment, etc.), as necessary. It may contain additives such as dyes, etc.), antioxidants, chain transfer agents, plasticizers, softeners, surfactants, antistatic agents, etc., to the extent that they do not impair the effects of the present invention. Note that such additives can be used alone or in combination of two or more.

The method for producing the adhesive layer (particularly the acrylic adhesive layer) of the present invention is not particularly limited, but for example, the adhesive composition is coated on a base material (including a resin layer and a glass layer described below) or a release liner. The pressure-sensitive adhesive composition layer may be coated (coated) on a base material (including a resin layer and a glass layer described below) or a release liner, and the resulting pressure-sensitive adhesive composition layer may be dried and cured. An example of this method is to irradiate the resulting adhesive composition layer with active energy rays to cure it. Moreover, if necessary, it may be further dried by heating.

Examples of the active energy rays include ionizing radiation such as α rays, β rays, γ rays, neutron beams, and electron beams, and ultraviolet rays, with ultraviolet rays being particularly preferred. Furthermore, the irradiation energy, irradiation time, irradiation method, etc. of the active energy rays are not particularly limited.

The pressure-sensitive adhesive composition can be produced by a known or commonly used method. For example, a solvent-based acrylic pressure-sensitive adhesive composition can be produced by mixing additives (for example, ultraviolet absorbers, etc.) into a solution containing the acrylic polymer, if necessary. For example, an active energy ray-curable acrylic pressure-sensitive adhesive composition can be prepared by mixing an additive (for example, an ultraviolet absorber, etc.) with the mixture of acrylic monomers or a partial polymer thereof, if necessary. It can be made.

Note that a known coating method may be used to apply (coating) the pressure-sensitive adhesive composition. For example, coaters such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, a spray coater, a comma coater, and a direct coater may be used.

In particular, when forming an adhesive layer using an active energy ray-curable adhesive composition, it is preferable that the active energy ray-curable adhesive composition contains a photopolymerization initiator. In addition, when the active energy ray-curable pressure-sensitive adhesive composition contains an ultraviolet absorber, it is preferable to include 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 that has absorption characteristics not only for ultraviolet light but also for visible light. This is because there is a concern that the effect of ultraviolet absorbers may inhibit curing by active energy rays, but if the adhesive composition contains a photoinitiator that has light-absorbing properties over a wide wavelength range, the adhesive composition will have high photocurability. This is because it is easier to obtain.

Regarding the adhesive layer, the creep amount Cr ₇₀ (μm) at 70° C. is 200 μm or less.

The creep amount Cr ₇₀ of the adhesive layer at 70° C. can be evaluated as follows (see FIG. 10). The optical laminate of the adhesive layer 104 and the support film 105 to be evaluated is cut into a strip of 20 mm x 30 mm to form a test piece 106. The support film 105 is disposed for the purpose of suppressing deformation of the load-applied portion of the adhesive layer 104 during the test, and thereby measuring the creep amount Cr ₇₀ with higher accuracy. For example, a resin film such as a polyethylene terephthalate (PET) film can be used as the support film 105. A resin layer may be used instead of the support film 105. The thickness of the support film 105 may be such that it does not deform itself under the above load, and is, for example, 20 to 200 μm. Next, as shown in FIGS. 10(a) and 10(b), a test piece 106 is attached to the surface of a stainless steel test plate 107 using an adhesive layer 104 at a joint surface measuring 20 mm in length x 20 mm in width. Note that FIG. 10(b) is a cross section BB in FIG. 10(a). The test piece 106 is attached to the test plate 107 so that no air bubbles are mixed between the test plate 107 and the adhesive layer 104. After pasting by hand, the test plate 107 was placed in an autoclave at 5 atm (absolute pressure) for 15 minutes to homogenize the bond between the test plate 107 and the adhesive layer 104, and then the pressure at 60° C. Leave to age under atmosphere for 2 hours. Next, the test plate 107 and the test piece 106 are held vertically with the test plate 107 facing upward and left in an atmosphere of 70°C for at least 5 minutes. A weight is fixed at the center of the lower end and a load 108 of 500 gf is applied vertically downward. The amount of creep (deviation amount) of the adhesive layer 104 with respect to the test plate 107 after 3600 seconds from the start of applying the load 108 is measured as the amount of fall of the weight, and is defined as the amount of creep Cr ₇₀ . A laser displacement meter can be used to measure the amount of weight fall.

The creep amount Cr ₇₀ of the adhesive layer is, for example, preferably 180 μm or less, more preferably 160 μm or less, even more preferably 140 μm or less, particularly preferably 120 μm or less, and most preferably 100 μm or less. The creep amount Cr ₇₀ of the adhesive layer is, for example, preferably 20 μm or more, more preferably 50 μm or more, still more preferably 70 μm or more, particularly preferably 90 μm or more.

When the creep amount Cr ₇₀ (μm) of the adhesive layer is 200 μm or less, it is possible to prevent crease marks from remaining on the optical laminate when the optical laminate is bent. Specifically, when the adhesive layer is held in a bent state for a long time, the adhesive layer gradually deforms. According to the time-temperature conversion rule for the adhesive layer, deformation of the adhesive layer over a long period of time can be treated as deformation of the adhesive layer under high temperature.

When the optical laminate includes a plurality of adhesive layers, the plurality of adhesive layers may have the same configuration or different configurations. As long as at least one of the plurality of adhesive layers satisfies the condition that the creep amount Cr ₇₀ (μm) is 200 μm or less, it is not necessary for all the adhesive layers to satisfy the above condition. It is more preferable that the number of adhesive layers satisfying the above conditions is large among the pressure-sensitive adhesive layers, and it is even more preferable that all of the plurality of resin layers satisfy the above conditions. The problem of folding marks tends to be more noticeable on the viewing side of the optical laminate. Therefore, it is preferable that the adhesive layer closest to the viewer among the plurality of adhesive layers has a creep amount Cr ₇₀ (μm) at 70° C. of 200 μm or less.

Examples of methods for producing an adhesive layer having a creep amount Cr ₇₀ (μm) of 200 μm or less include the following methods.

First, methods using a solvent-based adhesive composition (solvent-based first to fourth methods) will be described. The first solvent-based method uses an acrylic polymer copolymerized with a (meth)acrylic acid alkyl ester having a long-chain alkyl group. Here, in the first solvent-based method, it is preferable that the (meth)acrylic acid alkyl ester having a long-chain alkyl group accounts for 40% by weight or more and 99% by weight of all monomers.

In the second solvent-based method, a peroxide crosslinking agent is used alone as a crosslinking agent, and is added in an amount of 0.5 parts by weight or more and 5 parts by weight or less per 100 parts by weight of the acrylic polymer.

In the third solvent-based method, a peroxide-based cross-linking agent and an isocyanate-based cross-linking agent are used together as cross-linking agents, and the weight ratio of the peroxide-based cross-linking agent to the isocyanate-based cross-linking agent (peroxide-based cross-linking agent/isocyanate-based cross-linking agent) is (type crosslinking agent) is 1.2 or more and 500 or less, and the amount of the peroxide crosslinking agent added is 0.2 parts by weight or more per 100 parts by weight of the acrylic polymer.

In the fourth solvent-based method, in the second or third solvent-based method, 1 part by weight or more and 70 parts by weight or less of an acrylic oligomer is further added to 100 parts by weight of the acrylic polymer.

Next, methods using active energy ray-curable adhesive compositions (active energy ray-curable first method to second method) will be described. In the first active energy ray-curable method, a mixture (monomer (mixture) or a partially polymerized product of the mixture is polymerized together with a polyfunctional monomer.

In addition, in the second method of active energy ray curing, in the first method of active energy ray curing, an alkyl group having 10 to 30 carbon atoms is used as a (meth)acrylic acid alkyl ester having a long chain alkyl group. A mixture (monomer mixture) of a (meth)acrylic monomer having the following and a (meth)acrylic monomer having an alkyl group having 6 or more and 9 or less carbon atoms, or a partial polymer of the mixture is used.

Here, in the first method and the second method of active energy ray curing type, it is preferable that the content of the (meth)acrylic acid alkyl ester having a long-chain alkyl group in all monomers is 60% by weight or more. , more preferably 70% by weight or more, on the other hand, preferably 100% by weight or less, and more preferably 99% by weight or less. Furthermore, when using a mixture of a (meth)acrylic monomer having an alkyl group having 10 to 30 carbon atoms and a (meth)acrylic monomer having an alkyl group having 6 to 9 carbon atoms, the mixing ratio is ( (meth)acrylic monomer having an alkyl group having 10 to 30 carbon atoms): ((meth)acrylic monomer having an alkyl group having 6 to 9 carbon atoms) = 40:60 to 90:10 preferable.

The 500% modulus of the adhesive layer is not particularly limited, but is preferably 0.05 to 0.2 N/mm ² , more preferably 0.06 to 0.18 N/mm ² , and more preferably 0.05 to 0.2 N/mm 2 . 08 to 0.16 N/mm ² , more preferably 0.1 to 0.15 N/mm ² , more preferably 0.085 to 0.2 N/mm ² , even more preferably 0.1 to 0.2 N/mm ² , particularly preferably 0.12 to 0.2 N/mm ² , most preferably 0.15 to 0.2 N/mm ² . By adjusting to the above range, the cohesive force of the adhesive layer is ensured, and cracks in each layer and peeling due to cohesive failure of the adhesive layer can be prevented when bending under normal temperature (room temperature) environment or especially in high temperature environment. There is a tendency to prevent this from occurring. The 500% modulus of the adhesive layer is the stress (tensile stress) generated in the adhesive layer when 500% elongation is applied to the adhesive layer by a tensile force in one direction, based on the initial cross-sectional area of the adhesive layer. It is a characteristic expressed by the value divided by The 500% modulus of the adhesive layer can be evaluated as follows.

The adhesive layer to be evaluated is cut out into a strip of 30 mm x 100 mm. Next, the cut out adhesive layer is wound in the direction of the long side so as not to include air bubbles to obtain a cylindrical test piece having a height of 30 mm corresponding to the length of the short side. Next, the obtained test piece is set in a tensile testing machine such as Tensilon, and a uniaxial tensile test is performed in the height direction to obtain an elongation-stress curve of the adhesive layer. In addition, the preparation of the test piece and the uniaxial tensile test are carried out at room temperature (for example, 23° C.), and the initial distance between the chucks in the uniaxial tensile test is 10 mm, and the tensile speed is 300 mm/min. From the obtained elongation-stress curve, the stress at 100% elongation (distance between chucks at this time is 20 mm) is determined, and this is divided by the initial cross-sectional area of the test piece to obtain the 500% modulus of the adhesive layer.

The 700% modulus of the adhesive layer is, for example, 0.05 to 0.3 N/mm ² . The 700% modulus of the adhesive layer is the stress (tensile stress) generated in the adhesive layer when a 700% elongation is applied to the adhesive layer by a tensile force in one direction, based on the initial cross-sectional area of the adhesive layer. It is a characteristic expressed by the value divided by The 700% modulus of the adhesive layer can be evaluated using the method described above for the 500% modulus of the adhesive layer.

The 700% modulus of the adhesive layer is preferably 0.1 to 0.3 N/mm ² , more preferably 0.13 to 0.3 N/mm ² , and 0.18 to 0.3 N/mm 2 . It is more preferably 0.23 to 0.3 N/mm ² , and particularly preferably 0.23 to 0.3 N/mm ² . By adjusting to the above range, the cohesive force of the adhesive layer is ensured, and cracks in each layer and peeling due to cohesive failure of the adhesive layer can be prevented when bending under normal temperature (room temperature) environment or especially in high temperature environment. There is a tendency to prevent this from occurring.

In order to make the 500% modulus of the adhesive layer 0.085 to 0.2 N/mm ² , in the solvent-type adhesive composition, a (meth)acrylic monomer having an alkyl group having 4 to 12 carbon atoms is used. Further, an isocyanate-based crosslinking agent and a peroxide-based crosslinking agent are used in combination, and the weight ratio of peroxide-based crosslinking agent to isocyanate-based crosslinking agent (peroxide-based crosslinking agent/isocyanate-based crosslinking agent) is It is desirable that the adhesive composition is crosslinked by adjusting the crosslinking agent (crosslinking agent) to have a molecular weight of 1.5 to 200. This tends to make it easier to obtain an adhesive layer having the above modulus.

In addition, when using an acrylic oligomer in preparing the adhesive layer, it is recommended to use an isocyanate-based crosslinking agent and a peroxide-based crosslinking agent together in a solvent-based adhesive composition to obtain an adhesive having the above-mentioned modulus. There is a tendency that it becomes easier to obtain a drug layer. Specifically, an acrylic oligomer having a weight average molecular weight (Mw) of 3,000 or more and 10,000 or less is used, and the weight ratio of the peroxide crosslinking agent to the isocyanate crosslinking agent is 40 or more and 150 or less.

In the case of an active energy ray-curable adhesive composition, a (meth)acrylic monomer having an alkyl group having 6 to 30 carbon atoms is used, and a mixture of monomer components (monomer mixture) excluding polyfunctional monomers or a partial polymerization thereof is used. By polymerizing with 0.05 to 3% by weight of polyfunctional acrylate based on 100% by weight of the material, it tends to be easier to obtain an adhesive layer having the above modulus while exhibiting a crosslinking effect. be.

The storage modulus G' of the adhesive layer at 25° C. is preferably 1×10 ⁵ Pa or less. The peak value of tan δ (loss tangent) indicating the glass transition temperature (Tg) of the adhesive layer is preferably 3 or less. Further, the storage modulus G' is more preferably 8×10 ⁴ Pa or less, even more preferably 6×10 ⁴ Pa or less, particularly preferably 4×10 ⁴ Pa or less, and 3× Most preferably it is 10 ⁴ Pa or less. Further, the peak value of tan δ is more preferably 2.5 or less, even more preferably 2 or less, particularly preferably 1.5 or less, and most preferably 1 or less. The peak value of tan δ indicating the storage modulus G' and Tg of the adhesive layer at 25°C is within the above range.In other words, by keeping the storage modulus G' low, the adhesive layer is easily distorted when bent. However, by keeping the peak value of tan δ low, strain stress is difficult to diffuse, and by making the adhesive layer easily distorted, it is possible to bend or open the optical laminate even with a light force (load). There is a tendency to Furthermore, by making it difficult to diffuse the strain stress, the strain stress generated during bending becomes energy when returning from the bent state to the flat state, making it easier to return from the bent state to the flat state, and it is assumed that the bending angle increases. .

The loss modulus G'' of the adhesive layer at 25° C. is preferably 1×10 ⁵ Pa or less, more preferably 8×10 ⁴ Pa or less, and 4×10 ⁴ Pa or less. More preferred. The loss elastic modulus G'' of the adhesive layer at 25°C is within the above range.In other words, by keeping the loss elastic modulus G'' low, the adhesive layer is difficult to adjust to the bent state and when returning to the flat state. There is a tendency that the bending angle can be increased.

The storage modulus G' and loss modulus G'' of the adhesive layer can be measured, for example, by the following method. First, a measurement sample made of the material that makes up the adhesive layer is prepared. The shape of the measurement sample is, for example, disc-shaped (bottom diameter: 7.9 mm, thickness: 2 mm). Next, dynamic viscoelasticity measurement is performed on the measurement sample. For dynamic viscoelasticity measurement, for example, "Advanced Rheometric Expansion System (ARES)" manufactured by Rheometric Scientific can be used. Dynamic viscoelasticity measurement is performed, for example, under the following conditions. Based on the results of the dynamic viscoelasticity measurement, the storage modulus G' and loss modulus G'' of the adhesive layer can be determined.
(Measurement condition)
Deformation mode: Torsion Measurement temperature: -70℃~150℃
Heating rate: 5℃/min

The tan δ (loss tangent) of the adhesive layer at the glass transition temperature (Tg) can be calculated using the following formula.
tan δ (loss tangent) = G"/G'

The gel fraction of the adhesive layer is preferably 55 to 90% by weight, more preferably 57 to 90% by weight, even more preferably 60 to 88% by weight, even more preferably 62 to 88% by weight, and particularly preferably is between 65 and 86% by weight, most preferably between 70 and 86% by weight. When the gel fraction of the adhesive layer is within the above range, the appearance (glue dents, etc.), workability, durability, and flexibility will be good, and in particular, flexibility will be compatible in both room temperature and high temperature environments. It tends to be easier.

The upper limit of the glass transition temperature (Tg) of the adhesive layer is preferably 5° C. or lower. When considering flexibility in a low temperature environment or in a high speed range, the temperature is more preferably −20° C. or lower, and still more preferably −25° C. or lower. If the Tg of the adhesive layer is within this range, the adhesive layer will not become hard even when bending in a low temperature environment or at a high bending speed of more than 1 second/time, and will have excellent stress relaxation properties. It is possible to realize a bendable or foldable optical laminate for an OLED display and an OLED display comprising the optical laminate for an OLED display.

(Polarizer)
The polarizing plate (sometimes referred to as a polarizing film) constituting the optical element of the present invention is provided with an OLED display device on the viewing side of the OLED element from the viewpoint of improving antireflection properties, shock absorption properties, and ultraviolet absorption properties. . Although the polarizing plate is not particularly limited, it may include a polarizer and a transparent protective film on at least one side of the polarizer. The transparent protective film may have the same structure as the resin layer. That is, the polarizing plate includes a polarizer and a resin layer on at least one side of the polarizer, and the resin layer may have a moisture permeability of 50 (g/m ² ·24 h) or more.

The polarizer is not particularly limited, and for example, a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, a partially saponified ethylene/vinyl acetate copolymer film, etc., is coated with iodine or dichroic dye. Examples include polyene-based oriented films such as those obtained by adsorbing a dichroic substance and uniaxially stretched, dehydrated polyvinyl alcohol, and dehydrochloric acid treated polyvinyl chloride. Among these, a polarizer made of a polyvinyl alcohol film and a dichroic substance such as iodine is preferred. The thickness of these polarizers is not particularly limited, but is preferably, for example, 5 to 80 μm, more preferably 10 to 40 μm.

A polarizer made by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching it can be produced, for example, by dyeing polyvinyl alcohol by immersing it in an aqueous solution of iodine and stretching it to 3 to 7 times its original length. If necessary, it can also be immersed in an aqueous solution of potassium iodide or the like which may contain boric acid, zinc sulfate, zinc chloride, or the like. Furthermore, if necessary, the polyvinyl alcohol film may be washed with water by immersing it in water before dyeing. By washing the polyvinyl alcohol film with water, dirt and anti-blocking agents on the surface of the polyvinyl alcohol film can be washed away, and by swelling the polyvinyl alcohol film, uneven dyeing can be prevented. You can also do it. Stretching may be carried out after dyeing with iodine, or may be carried out while dyeing. Alternatively, it may be stretched and then dyed with iodine. Furthermore, it can be stretched in an aqueous solution of boric acid, potassium iodide, etc. or in a water bath.

As the polarizer, a thin polarizer with a thickness of 10 μm or less can also be used. From the viewpoint of thinning, the thickness is preferably 1 to 7 μm. Such a thin polarizer is preferable because it has less unevenness in thickness, has excellent visibility, has less dimensional change, has excellent durability, and can also be made thinner as a polarizing plate.

A thin polarizer can be obtained, for example, by a manufacturing method including a process of stretching a polyvinyl alcohol resin layer and a resin base material for stretching in the state of an optical laminate, and a process of dyeing. With this manufacturing method, even if the polyvinyl alcohol resin is thin, it can be stretched without problems such as breakage due to stretching because it is supported by the stretching resin base material.

The above-mentioned thin polarizing film is produced by stretching in a boric acid aqueous solution because it can be stretched to a high magnification and improves polarization performance among the manufacturing methods that include stretching and dyeing in the state of an optical laminate. Preferably, those obtained by a manufacturing method including a step, and particularly preferably, those obtained by a manufacturing method including an auxiliary step of stretching in air before stretching in an aqueous boric acid solution.

The above-mentioned transparent protective film is not particularly limited, but it is preferably a transparent protective film made of a material with excellent transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, etc., such as polyethylene terephthalate or polyethylene naphthalate. Polyester polymers such as phthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, styrene polymers such as polystyrene and acrylonitrile-styrene copolymer (AS resin), polycarbonate polymers, etc. can be mentioned. In addition, polyolefin polymers such as polyethylene, polypropylene, polyolefins having a cyclo- or norbornene structure, ethylene-propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamides, imide polymers, and sulfone polymers. , polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or Blends of the above polymers are also examples of polymers forming the transparent protective film. The transparent protective film can also be formed as a cured layer of thermosetting or ultraviolet curing resin such as acrylic, urethane, acrylic urethane, epoxy, or silicone resin.

The thickness of the transparent protective film can be determined as appropriate, but is generally about 1 to 500 μm from the viewpoint of strength, workability such as handleability, and thin film properties.

It is preferable that the polarizer and the transparent protective film are in close contact with each other via a water-based adhesive or the like. Examples of water-based adhesives include, but are not limited to, isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl latex-based adhesives, water-based polyurethanes, and water-based polyesters. Examples of adhesives for the polarizer and transparent protective film other than water-based adhesives include ultraviolet curable adhesives and electron beam curable adhesives. Electron beam curable adhesives exhibit good adhesion to the various transparent protective films described above. These adhesives may contain metal compound fillers.

The surface of the transparent protective film to which the polarizer is not attached may be treated with a hard coat layer, antireflection treatment, or treatment for the purpose of preventing sticking, diffusion, or antiglare.

As the transparent protective film, one that has a retardation and can function as an optical compensation layer (sometimes referred to as a retardation film) can be used. The retardation characteristics of the transparent protective film having a retardation can be appropriately adjusted to a value required for optical compensation. As such a retardation film, a stretched film can be suitably used. In the above-mentioned retardation film, where nx is the refractive index in the slow axis direction, ny is the refractive index in the in-plane fast axis direction, and nz is the refractive index in the thickness direction, nx=ny>nz, nx>ny >nz, nx>ny=nz, nx>nz>ny, nz=nx>ny, nz>nx>ny, nz>nx=ny, and those that satisfy the following relationships can be selected and used according to various uses. It will be done. Note that nx=ny includes not only the case where nx and ny are completely the same, but also the case where nx and ny are substantially the same. Further, ny=nz includes not only the case where ny and nz are completely the same, but also the case where ny and nz are substantially the same.

When the polarizing plate is used as a circularly polarizing plate, the retardation film is preferably a 1/4 wavelength plate in which the front retardation of the transparent protective film is 1/4 wavelength (approximately 100 to 170 nm).

When using a retardation film as the above-mentioned transparent protective film, a polarizing plate can be used in which a transparent protective film is provided on one surface of a polarizer and a retardation film is provided on the other surface. In that case, the installation location of the adhesive layer is not particularly limited, and it may be provided on the surface of the transparent protective film opposite to the surface in contact with the polarizer, or Although it may be provided on the surface opposite to the surface in contact with the surface, from the viewpoint of suppressing deterioration of the OLED element, it is preferable to provide it on at least one surface or both surfaces.

(adhesive layer)
An adhesive layer is a layer that can bond substances by intervening between adherends, and when an adherend that has been attached with an adhesive layer is peeled off, the adhesive layer has no practical adhesive strength. refers to something that does not have

Various adhesives can be used as the adhesive forming the adhesive layer (hereinafter sometimes referred to as "the adhesive layer of the present invention") constituting the optical element of the present invention. For example, isocyanate-based adhesive , polyvinyl alcohol adhesive, gelatin adhesive, vinyl latex adhesive, water-based polyester, and the like. These adhesives are usually used as adhesives made of aqueous solutions (water-based adhesives) and contain solid content of 0.5 to 60% by weight. Among these, polyvinyl alcohol adhesives are preferred, and acetoacetyl group-containing polyvinyl alcohol adhesives are more preferred.

The water-based adhesive may contain a crosslinking agent. As the crosslinking agent, a compound having at least two functional groups in one molecule that is reactive with components such as polymers constituting the adhesive is usually used, such as alkylene diamines; isocyanates; epoxies; Aldehydes: Amino-formaldehydes such as methylol urea and methylol melamine are included. The amount of the crosslinking agent in the adhesive is usually about 10 to 60 parts by weight per 100 parts by weight of components such as polymers constituting the adhesive.

Examples of the adhesive include active energy ray curable adhesives such as ultraviolet ray curable adhesives and electron beam curable adhesives in addition to those described above. Examples of the active energy ray-curable adhesive include (meth)acrylate adhesives. Examples of the curable component in the (meth)acrylate adhesive include a compound having a (meth)acryloyl group and a compound having a vinyl group. Examples of compounds having a (meth)acryloyl group include alkyl (meth)acrylates having 1 to 20 carbon atoms, alicyclic alkyl (meth)acrylates, and polycyclic alkyl (meth)acrylates. ) acrylate; hydroxyl group-containing (meth)acrylate; epoxy group-containing (meth)acrylate such as glycidyl (meth)acrylate; and the like. (Meth)acrylate adhesives include hydroxyethyl (meth)acrylamide, N-methylol (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, (meth)acrylamide, and (meth)acrylate. It may also contain a nitrogen-containing monomer such as acryloylmorpholine. The (meth)acrylate adhesive contains tripropylene glycol diacrylate, 1,9-nonanediol diacrylate, tricyclodecane dimethanol diacrylate, cyclic trimethylolpropane formal acrylate, dioxane glycol diacrylate, EO as a crosslinking component. It may also contain a polyfunctional monomer such as modified diglycerol tetraacrylate. Moreover, a compound having an epoxy group or an oxetanyl group can also be used as a cationic polymerization-curable adhesive. The compound having an epoxy group is not particularly limited as long as it has at least two epoxy groups in the molecule, and various commonly known curable epoxy compounds can be used.

The adhesive may contain appropriate additives as necessary. 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 trapping agents, and antioxidants. agents, tackifiers, fillers, plasticizers, leveling agents, foaming inhibitors, antistatic agents, heat stabilizers, hydrolysis stabilizers, and the like.

The adhesive may be applied to either one or both of the two adherends to be adhered. After bonding, a drying step can be performed to form the adhesive layer of the present invention, which is a coated and dried layer. After the drying step, ultraviolet rays or electron beams can be irradiated if necessary. The thickness of the adhesive layer of the present invention is not particularly limited, and when a water-based adhesive or the like is used, it is preferably about 30 to 5000 nm, more preferably about 100 to 1000 nm, and ultraviolet curing type When using an adhesive, an electron beam curing adhesive, etc., the thickness is preferably about 0.1 to 100 μm, more preferably about 0.5 to 10 μm.

(resin layer)
The resin layer constituting the optical element of the present invention (hereinafter sometimes referred to as the "resin layer of the present invention") is not particularly limited, but includes, for example, a plastic film. Materials for the plastic film include, for example, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), and cyclic olefin polymers (COP) (for example, product name "Arton" (manufactured by JSR Corporation)). ), product name "Zeonor" (manufactured by Nippon Zeon Co., Ltd.), etc.), acrylic resins such as polymethyl methacrylate (PMMA), polycarbonate (PC), triacetyl cellulose (TAC), polysulfone, polyarylate, polyether ether Plastic materials include ketone (PEEK), polyimide (PI), transparent polyimide (CPI), polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, and ethylene-propylene copolymer, which have excellent dimensional stability and do not shrink. Preferred are polyester resins such as hard polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), cyclic olefin polymers (COP), polycarbonate (PC), polyether ether ketone (PEEK), and transparent polyimide (CPI). More preferred are polyethylene terephthalate (COP), polyethylene terephthalate (PET), and transparent polyimide (CPI), and from the viewpoint of improving flexibility, cyclic olefin polymer (COP) and transparent polyimide (CPI) are particularly preferred. In addition, these plastic materials can be used individually or in combination of 2 or more types. The "resin layer" does not include a release liner that is peeled off when the optical element of the present invention is used (applied).

The resin layer of the present invention is preferably transparent. The total light transmittance of the resin layer of the present invention in the visible wavelength region (according to JIS K 7361-1) is not particularly limited, but is preferably 85% or more, more preferably 88% or more. Further, the haze (according to JIS K 7136) of the resin layer of the present invention is not particularly limited, but is preferably 1.5% or less, more preferably 1.0% or less.

The dimensional change rate D1 (%) of the resin layer from room temperature to 85°C and the dimensional change rate D2 (%) of the resin layer after being maintained at 85°C for 5 hours after reaching 85°C are: The following formula (A) is satisfied.
D1-D2≦0.4 (A)

More specifically, when measuring the dimensional change rate of the resin layer using thermomechanical analysis (TMA), the dimensional change rate of the resin layer at the time when the resin layer reaches 85° C. from room temperature. D1 (%) and the dimensional change rate D2 (%) of the resin layer after the resin layer reaches 85°C and is maintained at 85°C for 5 hours satisfy the above formula (A).

As used herein, room temperature means 20±10°C, typically 20°C. Additionally, thermomechanical analysis of the resin layer can be performed using a tensile probe. The dimensional change rates D1 and D2 of the resin layer mean, for example, the dimensional change rate in the direction in which the resin layer is bent.

The dimensional change rate D1 of the resin layer can be calculated using the following formula (C). L ₁ in formula (C) is the length of the resin layer at room temperature. L ₂ is the length of the resin layer when the temperature of the resin layer reaches 85°C.
Dimensional change rate D1 (%) = [(L ₂ - L ₁ )/L ₁ ] x 100 (C)

The dimensional change rate D2 of the resin layer can be calculated using the following formula (D). L ₁ in formula (D) is the same as in formula (C), and is the length of the resin layer at room temperature. L ₃ is the length of the resin layer after the resin layer reaches 85°C and is maintained at 85°C for 5 hours.
Dimensional change rate D2 (%) = [(L ₃ - L ₁ )/L ₁ ] x 100 (D)

The dimensional change rate D1 of the resin layer is, for example, 0.60% or less, preferably 0.50% or less, more preferably 0.40% or less, still more preferably 0.30% or less, particularly preferably 0. It is 20% or less, most preferably 0.10% or less. The lower limit of the dimensional change rate D1 is, for example, 0%.

The dimensional change rate D2 of the resin layer is, for example, 0.60% or less, preferably 0.50% or less, more preferably 0.40% or less, still more preferably 0.30% or less, particularly preferably 0. It is 20% or less, most preferably 0.10% or less. The lower limit of the dimensional change rate D2 is, for example, 0%.

The value of D1-D2 is preferably 0.35% or less, more preferably 0.30% or less, more preferably 0.30% or less, more preferably 0.25% or less, and even more preferably 0. It is 20% or less, more preferably 0.15% or less, particularly preferably 0.10% or less. The lower limit of D1-D2 is, for example, 0%.

When a resin layer that satisfies the above formula (A) is bent and placed in a high-temperature environment, the shrinkage rate (D1-D2) of the resin layer is small, so the resin layer will absorb the stress (strain) generated when it is bent. It is possible to maintain the state in which it is held. In the resin layer, stress (strain) is retained and a high energy state is maintained, so when the resin layer is released from the bent state, the force (restoring force) that tries to return to the original low energy state is large. It is easy to return to the original state. As a result, the OLED display device is less prone to crease marks (bent corners). On the other hand, in a resin layer that does not satisfy the above formula (A), that is, a resin layer with a large D1-D2, the stress (strain) generated when bending is relaxed by the contraction of the resin layer, resulting in a low energy state. Therefore, the restoring force becomes small and it is difficult to return to the original state when released from the bent state.

When the optical laminate includes a plurality of resin layers, the plurality of resin layers may have the same configuration or may have different configurations. As long as at least one resin layer among the plurality of resin layers satisfies the above formula (A), all the resin layers do not need to satisfy the above formula (A). It is more preferable that the number of resin layers satisfying the formula (A) is large, and it is even more preferable that all of the plurality of resin layers satisfy the above formula (A). Note that fold marks tend to occur on the viewing side of the OLED display device, so when the optical laminate includes a plurality of resin layers, the resin layer located closest to the viewing side among the plurality of resin layers is It is preferable that formula (A) is satisfied.

In the optical laminate for an OLED display device of the present invention, the strain occurring in the resin layer at the yield point of the resin layer is within the range allowed by the design of the OLED display device in which the optical laminate for an OLED display device is used. It is preferable that the strain ε is larger than the maximum strain ε that occurs in the resin layer when the resin layer is bent to the maximum extent within the range. Such a characteristic may be hereinafter referred to as "characteristic A." In this case, even if the OLED display device is bent, the yield point of the resin layer is not exceeded, so no bending marks are produced.

The yield point of the resin layer can be determined, for example, by the following method. First, a tensile test is performed on the resin layer in accordance with JIS K7161-1:2014, and a stress-strain curve is created based on the results. In the created stress-strain curve, the first point where strain increases without an increase in stress is regarded as the yield point of the resin layer. If the yield point cannot be determined by this method, the point at which a permanent strain of 0.2% occurs when stress is removed in a tensile test is considered to be the yield point of the resin layer.

The strain generated in the resin layer at the yield point of the resin layer is, for example, preferably 1.50% or more, more preferably 1.52% or more, even more preferably 1.53% or more, particularly preferably 1.54% or more. , most preferably 1.55% or more. Further, the above strain may be 1.60% or more. The upper limit of the strain that occurs in the resin layer at its yield point is not particularly limited, but is preferably 3.00%, more preferably 2.50%, for example.

With reference to FIG. 14, a method for specifying the maximum strain ε (%) that occurs in the resin layer 142 when the OLED display device 300 is bent to the maximum extent allowed by its design will be described. In FIG. 14(A), the OLED display device 300 includes two rigid parts 140a and 140b. Rigid parts 140a and 140b are lined up in the in-plane direction of OLED display device 300. Between the rigid parts 140a and 140b, there is a flexible part 141 that is thinner than the rigid parts 140a and 140b and forms a recessed part on one main surface of the OLED display device 300. The other main surface of OLED display device 300 is flat across rigid parts 140a and 140b and flexible part 141, and this main surface functions as one screen. In the illustrated form, the resin layer 142 included in the optical laminate is exposed on this flat main surface. However, the resin layer 142 may be arranged on the flattest main surface side of the optical laminate, and a window may be separately arranged thereon.

The OLED display device 300 in FIG. 14(A) can be bent using the flexible portion 141 as a bending portion so that the rigid portion 140a and the rigid portion 140b are in contact with each other (FIG. 14(B)). In FIG. 14(B), one main surface of the rigid section 140a is in contact with one main surface of the rigid section 140b. FIG. 14(B) shows a state in which the OLED display device 300 is bent to the maximum extent within the design range. The strain that occurs in the resin layer 142 in this state is the maximum strain ε. As can be understood from FIG. 14(C), the resin layer 142 is bent at 180°. In this specification, the maximum strain ε is calculated using the following formula [11]. However, in Formula [11], the length I (mm) means the length (inner circumference) of the inner surface 143 having a curvature in a side view of the inner surface 143 of the resin layer 142. The length O (mm) means the length (outer circumference) of the outer surface 144 having a curvature in a side view of the outer surface 144 of the resin layer 142 .
Maximum strain ε (%) = {(length O - length I) / (2 x length I)} x 100 [11]

In FIG. 14C, the resin layer 142 is bent in a semicircular manner when viewed from the side. In this case, the length I is expressed by the following formula [12]. However, in equation [12], the bending diameter R (mm) is the curvature diameter at the bent portion of the inner surface 143 of the resin layer 142.
Length I = π x bending diameter R/2 [12]

In FIG. 14(C), the length O is expressed by the following formula [13]. However, in formula [13], the thickness t (mm) is the thickness of the resin layer 142.
Length O=π×(bending diameter R+2×thickness t)/2 [13]

When equations [12] and [13] are substituted into equation [11], the maximum strain ε is expressed by the following equation [14].
Maximum strain ε (%) = thickness t/bending diameter R x 100 [14]

The bending diameter R of the resin layer 142 when the OLED display device 300 is bent to the maximum extent allowed by its design is not particularly limited, but is preferably, for example, 30 mm or less, more preferably 15 mm or less, and Preferably it is 10 mm or less, particularly preferably 5 mm or less. The strain that occurs in the resin layer 142 at the yield point of the resin layer 142 is, for example, greater than the maximum strain ε that occurs in the resin layer 142 when the OLED display device 300 is bent so that the bending diameter R is 3.5 mm. It's also big.

Usually, the maximum folded form of the OLED display device 300 is determined depending on its design. FIG. 15A shows a state in which the OLED display device 300 is bent to the maximum extent within the design range. Also in this case, the maximum strain ε generated in the resin layer 142 in this state can be calculated from equation [11] based on the length I and the length O shown in FIG. 15(B).

As shown in FIG. 16(A), the OLED display device 300 may be designed to be drawn in while being wrapped around a roller 145 and being bent. Also for such an OLED display device 300, the maximum strain ε occurring in the resin layer 142 can be calculated from equation [11] based on the length I and the length O shown in FIG. 16(B). Note that in order to draw in the OLED display device 300 further than in FIGS. 16(A) and 16(B), the OLED display device 300 is rolled up in a spiral shape. In this case, the OLED display device 300 is bent with a large curvature and is substantially folded.

In the laminate 10 of this embodiment, the resin layer 2 has the characteristic A, so that it maintains sufficient elasticity even if the OLED display device 300 is bent within the designed range. This elasticity can prevent crease marks from remaining on the optical laminate.

When the optical laminate includes a plurality of resin layers, the plurality of resin layers may be the same or different. Preferably, each of the plurality of resin layers has characteristic A. However, it is sufficient that at least one resin layer among the plurality of resin layers has characteristic A. It is preferable that the resin layer located closest to the viewer among the plurality of resin layers has characteristic A.

The thickness of the resin layer is not particularly limited, but is preferably 200 μm or less, more preferably 150 μm or less, more preferably 100 μm or less, more preferably 70 μm or less, more preferably 60 μm or less, even more preferably 50 μm or less, and particularly preferably It is 40 μm or less, most preferably 30 μm or less. The lower limit of the thickness of the resin layer is not particularly limited, but is preferably, for example, 5 μm, more preferably 10 μm.

The resin layer of the present invention is not particularly limited, but preferably contains an ultraviolet absorber (UVA) and a dye compound whose absorption spectrum has a maximum absorption wavelength in a wavelength range of 380 to 430 nm. When the resin layer of the present invention contains an ultraviolet absorber or the dye compound, it is possible to suppress deterioration of the OLED element due to ultraviolet rays contained in external light, and to obtain an OLED display device with excellent weather resistance. Further, it is possible to suppress deterioration of the high refractive index component of the adhesive layer due to ultraviolet rays, and maintain a high light absorption rate. In particular, by containing the ultraviolet absorber and the dye compound in the resin layer of the present invention, the content of the ultraviolet absorber and the dye compound in the adhesive layer of the present invention can be reduced. This is preferable because precipitation and bleed-out of the ultraviolet absorber and the dye compound therein can be suppressed.

As the ultraviolet absorber (UVA) and the dye compound contained in the resin layer of the present invention, the same ones as the ultraviolet absorber and the dye compound contained in the adhesive layer of the present invention can be used. In addition, the ultraviolet absorber and the said dye compound can be used individually or in combination of 2 or more types.

When the resin layer of the present invention contains an ultraviolet absorber or the dye compound, the content of each of the ultraviolet absorber or the dye compound in the resin layer of the present invention is not particularly limited, but the content of each of the ultraviolet absorber and the dye compound contained in external light is not limited. From the viewpoint of suppressing the deterioration of the OLED element due to ultraviolet rays and obtaining an OLED display device with excellent weather resistance, the amount is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight, based on 100 parts by weight of the resin layer. part or more, more preferably 0.1 part by weight or more. In addition, the upper limit of the content of the ultraviolet absorber and the dye compound suppresses the yellowing phenomenon of the adhesive due to the addition of the ultraviolet absorber, and provides excellent optical properties, high transparency, and excellent appearance. From the viewpoint of obtaining properties, the amount is preferably 10 parts by weight or less, more preferably 9 parts by weight or less, and even more preferably 8 parts by weight or less, based on 100 parts by weight of the resin layer.

When both the resin layer and the adhesive layer of the present invention contain an ultraviolet absorber or the dye compound, the total amount may be adjusted to fall within the above range.

The moisture permeability of the resin layer of the present invention is not particularly limited; 40 g/m ² ·24 h or more is more preferable, still more preferably 100 g/m ² ·24 h or more, particularly preferably 200 g/m ² ·24 h or more. The upper limit of the moisture permeability of the resin layer of the present invention is not particularly limited, but may be 1200 g/m ² ·24 h or less from the viewpoint of suppressing humid expansion. Since the resin layer of the present invention has high moisture permeability, there is a tendency for reliability in lighting performance to improve.

The moisture permeability of the resin layer of the present invention can be measured in accordance with JIS Z0208 at a temperature of 40°C and a relative humidity of 92%, and can be adjusted depending on the type and thickness of the resin constituting the resin layer of the present invention. Can be done.

(Glass layer)
The glass layer constituting the optical element of the present invention (hereinafter sometimes referred to as "the glass layer of the present invention") is not particularly limited, and any suitable layer can be employed depending on the purpose. The glass layer of the present invention is categorized by composition, and includes, for example, soda lime glass, boric acid glass, aluminosilicate glass, quartz glass, and the like. Furthermore, according to classification based on alkali components, alkali-free glass and low-alkali glass can be mentioned. The content of alkali metal components (eg, Na ₂ O, K ₂ O, Li ₂ O) in the glass is preferably 15% by weight or less, more preferably 10% by weight or less.

The thickness of the glass layer of the present invention is preferably 20 μm or more, considering the surface hardness, airtightness, and corrosion resistance of glass. In addition, the glass layer of the present invention preferably has film-like flexibility and bendability, and since it is possible to suppress double images and project a clear image, The thickness is preferably 60 μm or less. The thickness of the glass layer of the present invention is more preferably 30 μm or more and 55 μm or less, particularly preferably 40 μm or more and 50 μm or less.

The light transmittance of the glass layer of the present invention at a wavelength of 550 nm is preferably 85% or more. The refractive index of the glass layer of the present invention at a wavelength of 550 nm is preferably 1.4 to 1.65. The density of the glass layer of the present invention is preferably 2.3 g/cm ³ to 3.0 g/cm ³ , more preferably 2.3 g/cm ³ to 2.7 g/cm ³ .

The method for forming the glass layer of the present invention is not particularly limited, and any suitable method can be adopted depending on the purpose. Typically, the glass layer of the present invention is prepared by heating a mixture containing a main raw material such as silica or alumina, an antifoaming agent such as mirabilite or antimony oxide, and a reducing agent such as carbon at a temperature of approximately 1400°C to 1600°C. It can be produced by melting at a high temperature, forming it into a thin plate shape, and then cooling it. Examples of the method for forming the glass layer of the present invention include a slot down-draw method, a fusion method, and a float method. The glass layer formed into a plate shape by these methods may be chemically polished with a solvent such as hydrofluoric acid, if necessary, in order to make the glass layer thinner or to improve its smoothness.

(Hard coat layer)
As long as the hard coat layer constituting the optical element of the present invention (hereinafter sometimes referred to as the "hard coat layer of the present invention") has sufficient surface hardness, excellent mechanical strength, and excellent light transmittance, , may be formed from any suitable resin. Specific examples of the resin include thermosetting resins, thermoplastic resins, ultraviolet curable resins, electron beam curable resins, and two-component mixed resins. Ultraviolet curable resins are preferred. This is because the hard coat layer can be formed with simple operation and high efficiency.

Specific examples of the ultraviolet curable resin include polyester-based, acrylic-based, urethane-based, amide-based, silicone-based, and epoxy-based ultraviolet curable resins. The UV-curable resin includes UV-curable monomers, oligomers, and polymers. Preferred ultraviolet curable resins include resin compositions containing acrylic monomer components or oligomer components having preferably two or more, more preferably three to six, ultraviolet polymerizable functional groups. Typically, a photopolymerization initiator is blended into the ultraviolet curable resin.

The hard coat layer of the present invention may be formed by any suitable method. For example, the hard coat layer of the present invention can be produced by coating a resin composition for forming a hard coat layer on a base material (including the resin layer and glass layer), drying it, and irradiating the dried coating film with ultraviolet rays. It can be formed by hardening.

The thickness of the hard coat layer of the present invention is, for example, 2 μm to 20 μm, preferably 4 μm to 15 μm.

The water contact angle of the hard coat layer of the present invention is preferably 95° or more, more preferably 100° or more, still more preferably 105° or more, from the viewpoint of antifouling properties.
The water contact angle of the hard coat layer of the present invention is measured in accordance with JIS R3257, and can be adjusted depending on the type of resin constituting the hard coat layer, curing conditions, etc.

The hard coat layer of the present invention preferably has a Vickers hardness of 80 or more, more preferably 90 or more, and still more preferably 100 or more from the viewpoint of excellent surface hardness and scratch resistance.
The Vickers hardness of the hard coat layer of the present invention is measured in accordance with JIS Z2244, and can be adjusted depending on the type of resin constituting the hard coat layer, curing conditions, etc.

The surface element ratio of carbon element on the surface of the hard coat layer of the present invention is 50 atomic % or less, preferably 45 atomic % or less, from the viewpoint of antifouling property, and the fluorine element ratio on the surface of the hard coat layer is 30 atomic % or more. be.
Further, the nitrogen element ratio on the surface of the hard coat layer is, for example, less than 1.5 atomic %, preferably 1.3 atomic % or less, and, for example, 0 atomic % or more.
The surface element ratios of fluorine, carbon, and nitrogen elements on the surface of the hard coat layer of the present invention can be measured by X-ray photoelectron spectroscopy, and are determined by the type of resin constituting the hard coat layer, curing conditions, etc. It can be adjusted by

(Anti-reflection layer)
As the antireflection layer constituting the optical element of the present invention (hereinafter sometimes referred to as "antireflection layer of the present invention"), any suitable configuration can be adopted, for example, (i) the optical film thickness is 120 nm; ~140 nm, a single layer of a low refractive index layer with a refractive index of 1.35 to 1.55, (ii) a laminate having an intermediate refractive index layer, a high refractive index layer, and a low refractive index layer in this order, (iii) Alternating multilayer laminates of high refractive index layers and low refractive index layers.

Examples of materials that can form 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 1.55.

The material of the low refractive index layer may be a cured product of a curable fluorine-containing resin. The curable fluorine-containing resin has, for example, a structural unit derived from a fluorine-containing monomer and a structural unit derived from a crosslinkable monomer. Specific examples of fluorine-containing monomers include fluoroolefins (fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole, etc.) , (meth)acrylic acid ester derivatives having a partially or completely fluorinated alkyl group (Viscoat 6FM (manufactured by Osaka Organic Chemical Co., Ltd.), M-2020 (manufactured by Daikin Corporation), etc.), completely or partially Examples include fluorinated vinyl ethers. Examples of crosslinkable monomers include (meth)acrylate monomers having crosslinkable functional groups in the molecule such as glycidyl methacrylate; (meth)acrylate monomers having functional groups such as carboxyl groups, hydroxyl groups, amino groups, and sulfonic acid groups; ((meth)acrylic acid, methylol (meth)acrylate, hydroxyalkyl (meth)acrylate, allyl (meth)acrylate, etc.). The fluorine-containing resin may have structural units derived from monomers other than the above-mentioned compounds (for example, olefin monomers, (meth)acrylate monomers, and styrene monomers).

Examples of materials that can form the high refractive index layer include titanium oxide (TiO ₂ ), niobium oxide (Nb ₂ O ₃ or Nb ₂ O ₅ ), tin-doped indium oxide (ITO), antimony-doped tin oxide (ATO), ZrO ₂ --TiO ₂ is mentioned. The refractive index of the high refractive index layer is typically about 1.60 to 2.20.

Examples of materials that can form a medium refractive index layer include titanium oxide (TiO ₂ ), a mixture of a material that can form a low refractive index layer, and a material that can form a high refractive index layer (for example, titanium oxide and oxide mixtures with silicon). The refractive index of the medium refractive index layer is typically about 1.50 to 1.85. The thicknesses of the low refractive index layer, the medium refractive index layer, and the high refractive index layer can be set so as to realize an appropriate optical film thickness depending on the layer structure of the antireflection layer, desired antireflection performance, and the like.

The antireflection layer of the present invention may be formed by a dry process (e.g., sputtering), a wet process (e.g., coating), or a combination of a dry process and a wet process. . Specific examples of the dry process include a PVD (Physical Vapor Deposition) method and a CVD (Chemical Vapor Deposition) method. Examples of the PVD method include a vacuum evaporation method, a reactive evaporation method, an ion beam assist method, a sputtering method, and an ion plating method. The CVD method includes a plasma CVD method.

As a specific example of the wet process, for example, a coating solution for forming an antireflection layer may be applied to form a coating film, and the coating film may be cured to form an antireflection layer. As a coating method, for example, a fountain coating method, a die coating method, a spin coating method, a spray coating method, a gravure coating method, a roll coating method, a bar coating method, or the like can be used. It is preferable to dry the coating film prior to the curing. The drying may be, for example, natural drying, air drying by blowing wind, heat drying, or a combination of these methods. The means for curing the coating film is not particularly limited, but ultraviolet curing is preferred.

The thickness of the antireflection layer of the present invention is, for example, about 20 nm to 300 nm.

(Anti-glare layer)
As the anti-glare layer constituting the optical element of the present invention (hereinafter sometimes referred to as the "anti-glare layer of the present invention"), any known material can be employed without restriction, and generally, it is It is formed as a layer in which inorganic or organic particles are dispersed as an anti-glare agent.

The anti-glare layer of the present invention is not particularly limited, but is formed using an anti-glare layer-forming material containing, for example, a resin, particles, and a thixotropy-imparting agent, and the particles and the thixotropy-imparting agent agglomerate. , convex portions are formed on the surface of the anti-glare layer of the present invention. With this configuration, the anti-glare layer has excellent display properties that combine anti-glare properties and prevention of white blur, and even though the anti-glare layer is formed using particle aggregation, It is possible to prevent the occurrence of protrusions on the surface of the anti-glare layer, which would cause defects in appearance, and improve the yield of the product.

Examples of the resin include thermosetting resins and ionizing radiation-curable resins that are cured by ultraviolet light or light. As the resin, it is also possible to use commercially available thermosetting resins, ultraviolet curable resins, and the like.

As the thermosetting resin or the ultraviolet curable resin, for example, a curable compound having at least one of an acrylate group and a methacrylate group that is cured by heat, light (ultraviolet light, etc.), electron beam, etc. can be used, for example, Silicone resins, polyester resins, polyether resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, oligomers or prepolymers such as acrylates and methacrylates of polyfunctional compounds such as polyhydric alcohols, etc. can give. These may be used alone or in combination of two or more.

For example, a reactive diluent having at least one of an acrylate group and a methacrylate group can also be used in the resin. The reactive diluent can be, for example, the reactive diluent described in JP-A No. 2008-88309, and includes, for example, monofunctional acrylate, monofunctional methacrylate, polyfunctional acrylate, polyfunctional methacrylate, and the like. As the reactive diluent, trifunctional or higher functional acrylates or trifunctional or higher functional methacrylates are preferred. This is because the hardness of the anti-glare layer of the present invention can be made excellent. Examples of the reactive diluent include butanediol glycerin ether diacrylate, isocyanuric acid acrylate, isocyanuric acid methacrylate, and the like. These may be used alone or in combination of two or more.

The resin preferably includes a urethane acrylate resin, and more preferably a copolymer of a curable urethane acrylate resin and a polyfunctional acrylate (eg, pentasritol triacrylate).

The main functions of the particles for forming the anti-glare layer of the present invention are to impart anti-glare properties by making the surface of the anti-glare layer uneven and to control the haze value of the anti-glare layer. shall be. The haze value of the anti-glare layer can be designed by controlling the difference in refractive index between the particles and the resin. Examples of the particles include inorganic particles and organic particles. The inorganic particles are not particularly limited, and include, for example, silicon oxide particles, titanium oxide particles, aluminum oxide particles, zinc oxide particles, tin oxide particles, zirconium oxide particles, calcium carbonate particles, barium sulfate particles, talc particles, kaolin particles, Examples include calcium sulfate particles. The organic particles are not particularly limited, and include, for example, polymethyl methacrylate resin powder (PMMA fine particles), silicone resin powder, polystyrene resin powder, polycarbonate resin powder, acrylic styrene resin powder, benzoguanamine resin powder, melamine resin powder, polyolefin. Examples include resin powder, polyester resin powder, polyamide resin powder, polyimide resin powder, polyfluoroethylene resin powder, and the like. One type of these inorganic particles and organic particles may be used alone, or two or more types may be used in combination.

The weight average particle diameter (D) of the particles is preferably within the range of 2.5 to 10 μm. By setting the weight average particle diameter of the particles within the above range, for example, it is possible to have better anti-glare properties and prevent white blurring. The weight average particle diameter of the particles is more preferably within the range of 3 to 7 μm. Note that the weight average particle diameter of the particles can be measured, for example, by the Coulter counting method. For example, using a particle size distribution measuring device (trade name: Coulter Multisizer, manufactured by Beckman Coulter) that uses the pore electrical resistance method, an electrolyte solution corresponding to the volume of the particles when the particles pass through the pores is measured. By measuring electrical resistance, the number and volume of the particles are determined, and the weight average particle diameter is calculated.

The shape of the particles is not particularly limited, and may be, for example, approximately spherical in the form of beads, or irregularly shaped such as powder, but is preferably approximately spherical, and more preferably has an aspect ratio. The particles are approximately spherical particles with a ratio of 1.5 or less, and most preferably spherical particles.

The proportion of the particles in the anti-glare layer of the present invention is preferably in the range of 0.2 to 12 parts by weight, more preferably in the range of 0.5 to 12 parts by weight, based on 100 parts by weight of the resin. It is preferably in the range of 1 to 7 parts by weight. By setting it within the above range, for example, it is possible to have better anti-glare properties and prevent white blurring.

The antiglare layer of the present invention may contain a thixotropy imparting agent. By including the thixotropy agent, the aggregation state of the particles can be easily controlled. Examples of the thixotropy imparting agent for forming the antiglare layer of the present invention include organic clay, oxidized polyolefin, and modified urea.

It is preferable that the organic clay is a clay that has been subjected to an organic treatment in order to improve its affinity with the resin. Examples of the organic clay include layered organic clay. The organic clay may be prepared in-house or a commercially available product may be used. Examples of the commercially available products include Lucentite SAN, Lucentite STN, Lucentite SEN, Lucentite SPN, Somasif ME-100, Somasif MAE, Somasif MTE, Somasif MEE, Somasif MPE (trade names, all manufactured by Co-op Chemical Co., Ltd.). ); Esben, Esben C, Esben E, Esben W, Esben P, Esben WX, Esben N-400, Esben NX, Esben NX80, Esben NO12S, Esben NEZ, Esben NO12, Esben NE, Esben NZ, Esben NZ70, Organite, Organite D, Organite T (trade names, all manufactured by Hojun Co., Ltd.); Kunipia F, Kunipia G, Kunipia G4 (trade names, all manufactured by Kunimine Industries Co., Ltd.); Thixogel VZ, Clayton HT and Kraton 40 (trade names, both manufactured by Rockwood Additives).

The oxidized polyolefin may be prepared in-house or a commercially available product may be used. Examples of the commercially available products include Disparon 4200-20 (trade name, manufactured by Kusumoto Kasei Co., Ltd.) and Fluonon SA300 (trade name, manufactured by Kyoeisha Chemical Co., Ltd.).

The modified urea is a reaction product of an isocyanate monomer or its adduct and an organic amine. The modified urea may be prepared in-house or a commercially available product may be used. Examples of the commercially available products include BYK410 (manufactured by Big Chemie).

The thixotropy imparting agent may be used alone or in combination of two or more.

It is preferable that the height of the convex portion from the average roughness line of the anti-glare layer of the present invention is less than 0.4 times the thickness of the anti-glare layer. More preferably, it is in the range of 0.01 times or more and less than 0.4 times, and still more preferably in the range of 0.01 times or more and less than 0.3 times. Within this range, it is possible to suitably prevent the formation of protrusions that would cause defects in appearance on the convex portion. The anti-glare layer of the present invention has convex portions with such heights, thereby making it difficult to cause defects in appearance. Here, the height from the average line can be measured, for example, by the method described in JP-A-2017-138620.

The proportion of the thixotropy imparting agent in the anti-glare layer of the present invention is preferably in the range of 0.1 to 5 parts by weight, more preferably in the range of 0.2 to 4 parts by weight, based on 100 parts by weight of the resin. .

The thickness (d) of the anti-glare layer of the present invention is not particularly limited, but is preferably within the range of 3 to 12 μm. By setting the thickness (d) of the anti-glare layer within the above range, for example, it is possible to prevent the optical laminate of the present invention from curling, and to avoid the problem of reduced productivity such as poor conveyance. Further, when the thickness (d) is within the above range, the weight average particle diameter (D) of the particles is preferably within the range of 2.5 to 10 μm, as described above. When the thickness (d) of the anti-glare layer of the present invention and the weight average particle diameter (D) of the particles are in the above-mentioned combination, the anti-glare properties can be further improved. The thickness (d) of the anti-glare layer of the present invention is more preferably within the range of 3 to 8 μm.

The relationship between the thickness (d) of the anti-glare layer of the present invention and the weight average particle diameter (D) of the particles is preferably within the range of 0.3≦D/d≦0.9. By having such a relationship, it is possible to obtain an anti-glare layer that has better anti-glare properties, can prevent white blurring, and has no defects in appearance.

In the anti-glare layer of the present invention, the particles and the thixotropy imparting agent aggregate to form convex portions on the surface of the anti-glare layer of the present invention. In the agglomerated portion forming the convex portion, a plurality of the particles are present in a state of being gathered in the surface direction of the anti-glare layer of the present invention. Thereby, the convex portion has a gentle shape. By having the convex portions having such a shape, the anti-glare layer of the present invention can maintain anti-glare properties and prevent white blurring, and can also be made less likely to cause defects in appearance. can.

The surface shape of the anti-glare layer of the present invention can be arbitrarily designed by controlling the aggregation state of particles contained in the anti-glare layer forming material. The agglomeration state of the particles can be controlled by, for example, the material of the particles (for example, the chemical modification state of the particle surface, the affinity for solvents and resins, etc.), the type and combination of resins (binder) or solvents, and the like. Here, the agglomeration state of the particles can be controlled by the thixotropy imparting agent contained in the anti-glare layer forming material of the present invention. As a result, the agglomeration state of the particles can be made as described above, and the convex portion can have a gentle shape.

In the anti-glare layer of the present invention, it is preferable that the number of appearance defects having a maximum diameter of 200 μm or more is one or less per 1 m ² of the anti-glare layer. More preferably, there is no appearance defect.

In the uneven shape of the surface of the anti-glare layer of the present invention, the average inclination angle θa (°) is preferably in the range of 0.1 to 5.0, more preferably in the range of 0.3 to 4.5. , more preferably in the range of 1.0 to 4.0, particularly preferably 1.6 to 4.0. Here, the average inclination angle θa is a value defined by the following formula (E). The average inclination angle θa is a value measured by the method described in JP-A-2017-138620, for example.
Average inclination angle θa=tan-1Δa (E)

In the above formula (E), Δa is the distance between the peaks and valleys of adjacent peaks in the standard length L of the roughness curve specified in JIS B 0601 (1994 edition), as shown in the formula (F) below. This is the value obtained by dividing the total (h1+h2+h3...+hn) of the difference (height h) from the lowest point by the reference length L. The roughness curve is a curve obtained by removing surface waviness components longer than a predetermined wavelength from a cross-sectional curve using a phase difference compensating high-pass filter. Further, the cross-sectional curve is a contour that appears at a cut end when the target surface is cut by a plane perpendicular to the target surface.
Δa=(h1+h2+h3...+hn)/L (F)

When θa is within the above range, the anti-glare property is more excellent and white blur can be prevented.

In forming the anti-glare layer of the present invention, it is preferable that the prepared anti-glare layer forming material (coating liquid) exhibits thixotropy, and has a Ti value defined below of 1.3 to 3.5. It is preferably in the range of 1.3 to 2.8, and more preferably in the range of 1.3 to 2.8.
Ti value = β1/β2
Here, β1 is the viscosity measured at a shear rate of 20 (1/s) using Rheostress 6000 manufactured by HAAKE, and β2 is the viscosity measured at a shear rate of 200 (1/s) using Rheostress 6000 manufactured by HAAKE. This is the viscosity measured under the following conditions.

When the Ti value is less than 1.3, defects in appearance are likely to occur, and properties regarding anti-glare properties and white blurring deteriorate. Furthermore, when the Ti value exceeds 3.5, the particles are less likely to aggregate and become more likely to be in a dispersed state.

The method for producing the anti-glare layer of the present invention is not particularly limited and may be produced by any method. For example, the anti-glare layer forming material (coated The anti-glare layer can be manufactured by preparing an anti-glare layer liquid), applying the anti-glare layer forming material (coating liquid) to form a coating film, and curing the coating film to form an anti-glare layer. It is also possible to use a transfer method using a mold, a method of imparting an uneven shape by an appropriate method such as sandblasting, embossing roll, etc.

The solvent is not particularly limited, and various solvents can be used, and one type may be used alone or two or more types may be used in combination. There are optimal solvent types and solvent ratios depending on the composition of the resin, the types and contents of the particles and the thixotropy-imparting agent, and the like. Examples of the solvent include, but are not limited to, alcohols such as methanol, ethanol, isopropyl alcohol, butanol, and 2-methoxyethanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclopentanone; methyl acetate, ethyl acetate. , esters such as butyl acetate; ethers such as diisopropyl ether and propylene glycol monomethyl ether; glycols such as ethylene glycol and propylene glycol; cellosolves such as ethyl cellosolve and butyl cellosolve; aliphatic hydrocarbons such as hexane, heptane, and octane. Aromatic hydrocarbons such as benzene, toluene, xylene, etc.

By appropriately selecting the solvent, the thixotropic property of the antiglare layer forming material (coating liquid) can be expressed favorably by the thixotropy imparting agent. For example, when using organoclay, toluene and xylene can be preferably used alone or in combination; for example, when using an oxidized polyolefin, methyl ethyl ketone, ethyl acetate, propylene glycol monomethyl ether can preferably be used alone. They can be used or used in combination. For example, when using modified urea, butyl acetate and methyl isobutyl ketone can be suitably used alone or in combination.

Various leveling agents can be added to the anti-glare layer forming material. As the leveling agent, for example, a fluorine-based or silicone-based leveling agent can be used for the purpose of preventing uneven coating (uniform coating surface). The leveling agent is selected as appropriate depending on the case where antifouling properties are required on the surface of the anti-glare layer of the present invention, or when an anti-reflection layer or a layer containing an interlayer filler is formed on the anti-glare layer. be able to. For example, by including the thixotropy imparting agent, the coating liquid can exhibit thixotropy, so that coating unevenness is less likely to occur. For this reason, it has the advantage that, for example, the options for the leveling agent can be expanded.

The blending amount of the leveling agent is, for example, 5 parts by weight or less, preferably in the range of 0.01 to 5 parts by weight, based on 100 parts by weight of the resin.

If necessary, pigments, fillers, dispersants, plasticizers, ultraviolet absorbers, surfactants, antifouling agents, antioxidants, etc. may be added to the anti-glare layer forming material within a range that does not impair performance. may be done. These additives may be used alone or in combination of two or more.

For the anti-glare layer forming material, a conventionally known photopolymerization initiator as described in JP-A No. 2008-88309, for example, can be used.

As a method for applying the anti-glare layer forming material, for example, a coating method such as a fountain coating method, a die coating method, a spin coating method, a spray coating method, a gravure coating method, a roll coating method, a bar coating method, etc. may be used. I can do it.

The anti-glare layer forming material is applied to form a coating film, and the coating film is cured. It is preferable to dry the coating film prior to the curing. The drying may be, for example, natural drying, air drying by blowing wind, heat drying, or a combination of these methods.

The means for curing the coating film of the anti-glare layer forming material is not particularly limited, but ultraviolet curing is preferred. The irradiation amount of the energy ray source is preferably 50 to 500 mJ/cm ² as a cumulative exposure amount at an ultraviolet wavelength of 365 nm. If the irradiation amount is 50 mJ/cm ² or more, curing will be more sufficient, and the anti-glare layer formed will also have more sufficient hardness. Moreover, if it is 500 mJ/cm ² or less, coloring of the formed anti-glare layer can be prevented.

The antiglare layer of the present invention can be formed in the manner described above. Note that the antiglare layer may be formed by a manufacturing method other than the above-mentioned method. The hardness of the anti-glare layer of the present invention is influenced by the thickness of the layer in terms of pencil hardness, but preferably has a hardness of 2H or more.

The antiglare layer of the present invention may have a multilayer structure in which two or more layers are laminated.

The above-mentioned antireflection layer may be placed on the antiglare layer of the present invention. For example, one of the factors that reduces the visibility of an OLED display device is the reflection of light at the interface between the air and the anti-glare layer. The antireflection layer reduces surface reflection. Note that the antiglare layer and antireflection layer of the present invention may each have a multilayer structure in which two or more layers are laminated.

(middle class)
The intermediate layer constituting the optical element of the present invention (hereinafter sometimes referred to as the "intermediate layer of the present invention") is between the resin layer and the hard coat layer, antireflection layer, or antiglare layer. It is formed in Formation of this intermediate layer improves the adhesion between the resin layer and the hard coat layer, antireflection layer, or antiglare layer.

The mechanism by which the intermediate layer (also referred to as a permeable layer or a compatible layer) of the present invention is formed is not particularly limited, but for example, in the formation of the hard coat layer, antireflection layer, or antiglare layer, the hard coat layer is formed. It is formed during the process of applying, permeating, and drying a coating liquid for coating, a coating liquid for forming an antireflection layer, or a coating liquid for forming an anti-glare layer on a resin layer. In the drying step, for example, a coating liquid for forming a hard coat layer, a coating liquid for forming an antireflection layer, or a coating liquid for forming an anti-glare layer penetrates into the resin layer, and the resin derived from the resin layer and the hard coat are mixed. layer, an antireflection layer, or a resin derived from an antiglare layer. The resin contained in the intermediate layer is not particularly limited, and for example, the resin contained in the resin layer and the resin contained in the hard coat layer, antireflection layer, or antiglare layer are simply mixed (compatible). But that's fine. Further, the resin contained in the intermediate layer may be chemically treated by heating, light irradiation, etc., at least one of the resin contained in the resin layer and the resin contained in the hard coat layer, antireflection layer, or antiglare layer. It may be changing.

The thickness ratio R of the intermediate layer defined by the following formula (G) is not particularly limited, but is, for example, 0.10 to 0.80, for example, 0.15 or more, 0.20 or more, 0.25 or more, 0.30 or more, 0.40 or more, or 0.45 or more, for example, 0.75 or less, 0.70 or less, 0.65 or less, 0.60 or less, 0.50 or less, It may be 0.40 or less, 0.45 or less, or 0.30 or less. The thickness ratio R of the intermediate layer is, for example, 0.15 to 0.75, 0.20 to 0.70, 0.25 to 0.65, 0.30 to 0.60, 0.40 to 0.50. , 0.45 to 0.50, 0.15 to 0.45, 0.15 to 0.40, 0.15 to 0.30, or 0.20 to 0.30. The intermediate layer can be confirmed and its thickness can be measured, for example, by observing a cross section of the optical element with a transmission electron microscope (TEM).
R=[DC/(DC+DB)] (G)
In the formula (G), DB is the thickness [μm] of the hard coat layer, antireflection layer, or antiglare layer, and DC is the thickness [μm] of the intermediate layer.

When an intermediate layer is formed between the resin layer and the hard coat layer, antireflection layer, or antiglare layer, shear failure between the resin layer and the hardcoat layer, antireflection layer, or antiglare layer From the viewpoint of excellent adhesion, the strength is preferably 20 MPa or more, more preferably 50 MPa or more.

The shear fracture strength can be determined by the SAICAS method, and is determined by the type of resin layer, the composition of the coating liquid for forming the hard coat layer, the coating liquid for forming the antireflection layer, the coating liquid for forming the antiglare layer, and the film formation. It can be adjusted according to the law.

(shock absorption layer)
The shock absorbing layer (hereinafter sometimes referred to as "the shock absorbing layer of the present invention") constituting the optical element of the present invention may be composed of any suitable resin layer that can achieve a desired shock absorption rate. The resin layer may be composed of a resin film or an adhesive. The impact absorption layer typically contains epoxy resin, urethane resin, or acrylic resin. These resins may be used alone or in combination.

The thickness of the shock absorbing layer of the present invention is preferably 30 μm to 200 μm, more preferably 30 μm to 150 μm, and still more preferably 40 μm to 120 μm. If the thickness of the impact absorption layer of the present invention is within this range, an optical laminate having excellent impact resistance can be realized.

The storage modulus G' at 25° C. of the shock absorbing layer of the present invention is preferably 0.1 GPa or less, more preferably 0.01 MPa to 0.1 GPa. If the storage modulus of the impact-absorbing layer of the present invention is within this range, it has the advantage of absorbing impact and preventing cracking of the optical laminate. Furthermore, a synergistic effect with the above thickness effect may also be exhibited.

(Antistatic layer)
The antistatic layer constituting the optical element of the present invention (hereinafter sometimes referred to as the "antistatic layer of the present invention") is not particularly limited, but for example, it may be coated with a conductive coating liquid containing a conductive polymer. This is an antistatic layer formed. Specific coating methods include roll coating, bar coating, and gravure coating.

Examples of the conductive polymer include a conductive polymer in which a π-conjugated conductive polymer is doped with a polyanion. Examples of the π-conjugated conductive polymer include chain conductive polymers such as polythiophene, polypyrrole, polyaniline, and polyacetylene. Examples of the polyanion include polystyrene sulfonic acid, polyisoprene sulfonic acid, polyvinyl sulfonic acid, polyallylsulfonic acid, polyethyl acrylate sulfonic acid, and polymethacrylic carboxylic acid.

The thickness of the antistatic layer is preferably 1 nm to 1000 nm, more preferably 5 nm to 900 nm. The antistatic layer may have only one layer, or may have two or more layers.

The bending recovery property of the optical laminate of the present invention can be evaluated, for example, by the bending angle of the optical laminate. The bending angle of the optical laminate can be measured, for example, by the following method. First, as shown in FIG. 11, the optical laminate 111 is bent so that the main surface (the surface with the widest area) of the optical laminate 111 follows the upper and lower surfaces of the flat spacer 113, respectively. At this time, the bending diameter of the optical laminate 111 corresponds to the thickness T of the spacer 113. In this specification, the bending diameter means the curvature diameter determined by the curved surface that provides the maximum curvature on the inner surface of the optical laminate 111 in a state where the optical laminate 111 is bent. Next, the folded optical laminate 111 is sandwiched between supports 112a and 112b. Supports 112a and 112b are fixed with fixtures 114. Fixture 114 is, for example, polyimide tape. The bent optical laminate 111 is heated to 85° C. and left for 72 hours. Next, the temperature of the optical laminate 111 is lowered to room temperature (for example, 25° C.), and the spacer 113, supports 112a and 112b, and fixture 114 are removed. The optical laminate 111 is left in this state for 5 minutes. The bending angle θ (see FIG. 5B) remaining in the optical laminate 111 is measured. Note that a U-shaped expansion/contraction tester may be used to bend the optical laminate 111.

The bending angle θ of the optical laminate 111 measured by the above method is, for example, 10° or more, preferably 20° or more, preferably 30° or more, preferably 40° or more, and preferably The angle is 50° or more, more preferably 60° or more, particularly preferably 70° or more. When the bending angle θ of the optical laminate 111 is 40° or more, it is possible to sufficiently prevent bending marks from remaining on the optical laminate 111. The closer the bending angle θ of the optical laminate 111 is to 180°, the more the optical laminate 111 can be prevented from leaving fold marks. However, the upper limit of the bending angle θ of the optical laminate 111 may be 150° or 120°.

(Manufacturing method of optical laminate)
The method for producing the optical laminate of the present invention is not particularly limited, and the adhesive layer, adhesive layer, polarizing plate, resin layer, glass layer, hard coat layer, antireflection layer, and It can be manufactured by sequentially laminating a glare layer, an intermediate layer (compatible layer), a shock absorption layer, etc. on the viewing side of the OLED display panel of the present invention, and also constitutes the optical laminate of the present invention. It can be manufactured by preparing a laminate in advance and laminating it on the viewing side of the OLED display panel of the present invention. When a laminate constituting the optical laminate of the present invention is prepared in advance, it may be a laminate that constitutes the entire optical laminate of the present invention, or a laminate that constitutes a part of the optical laminate of the present invention. may be divided and laminated on the viewing side of the OLED display panel of the present invention.

The layers constituting the optical element of the present invention or the laminate thereof may be protected with a release liner or a surface protection film until use.

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

As the release liner, a conventional release paper or the like can be used, and examples thereof include, but are not limited to, a base material having a release treatment layer, a low-adhesive base material made of a fluoropolymer, and a low-adhesive base material made of a non-polar polymer. Examples include. Examples of the base material having the release treatment layer include plastic films and papers whose surface has been treated with a release agent such as silicone, long-chain alkyl, fluorine, and molybdenum sulfide. Examples of the fluoropolymer in the low-adhesive base material made of the fluoropolymer include polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, and chlorofluoroethylene. Examples include fluoroethylene-vinylidene fluoride copolymer. Furthermore, examples of the nonpolar polymer include olefin resins (eg, polyethylene, polypropylene, etc.). Note that the release liner can be formed by a known or commonly used method. Furthermore, the thickness of the release liner is not particularly limited.

(Surface protection film)
The outermost surface (the outermost surface on the viewing side) of the optical laminate of the present invention may be protected by a surface protection film. The surface protection film may be applied by the consumer. Note that the surface protection film does not constitute the optical element of the present invention and does not necessarily need to be provided.

As the surface protection film, any known or commonly used surface protection film can be used, and is not particularly limited, but for example, a plastic film having an adhesive layer on the surface can be used. Examples of the plastic film include polyester (polyethylene terephthalate, polyethylene naphthalate, etc.), polyolefin (polyethylene, polypropylene, cyclic polyolefin, etc.), polystyrene, acrylic resin, polycarbonate, epoxy resin, fluororesin, silicone resin, diacetate resin, Examples include plastic films formed from plastic materials such as triacetate resin, polyarylate, polyvinyl chloride, polysulfone, polyethersulfone, polyetheretherimide, polyimide, and polyamide. Examples of the adhesive layer include acrylic adhesives, natural rubber adhesives, synthetic rubber adhesives, ethylene-vinyl acetate copolymer adhesives, ethylene-(meth)acrylate copolymer adhesives, Examples include adhesive layers formed from one or more types of known or commonly used adhesives such as styrene-isoprene block copolymer adhesives and styrene-butadiene block copolymer adhesives. The adhesive layer may contain various additives (for example, antistatic agents, slip agents, etc.). Note that the plastic film and the adhesive layer may each have a single layer structure or a multilayer (multilayer) structure. Moreover, the thickness of the surface protection film is not particularly limited and can be selected as appropriate.

(OLED display device of the present invention)
An embodiment of an OLED display device in which an optical laminate of the present invention is laminated on the viewing 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 one embodiment of the basic configuration of an OLED display device in which the optical laminate of the present invention is laminated.

As shown in FIG. 2, in the OLED display device 200, layers constituting an optical laminate 20 are laminated on the viewing side (upper side in FIG. 2) of the OLED display panel 100. The OLED display panel 100 is not particularly limited, but may have the same configuration 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 is an adhesive layer or an adhesive layer, 22 is a polarizing plate, a resin layer, a glass layer, or a shock absorption layer, 23 is a hard coat layer or an anti-glare layer, 24 is an adhesive layer or an adhesive layer, 25 is a polarizing plate, a resin layer, a glass layer or a shock absorbing layer, 26 is an adhesive layer or an adhesive layer, 27 is a polarizing plate, A resin layer, a glass layer or a shock absorbing layer, 28 a hard coat layer or an antiglare layer, and 29 an antireflection layer. The laminated structure of the optical laminate 20 shown in FIG. 2 is not limited to this embodiment, and the optical element of the present invention may be configured between any layers of the laminated structure of the optical laminate 20 shown in FIG. Other layers may be inserted, and any layer of the layered structure of optical stack 20 shown in FIG. 2 may be absent.

In a preferred embodiment of the present invention, in FIG. 2, 21 is an adhesive layer, 22 is a resin layer, 23 is a hard coat layer, 24 is an adhesive layer, 25 is a glass layer, 26 is an adhesive layer, and 27 is an adhesive layer. The resin layer 28 is a hard coat layer without the antireflection layer 29, and at least one of the adhesive layers 21, 24, and 26 is an adhesive layer having light scattering properties. FIG. 3 shows an OLED display device 300 according to this embodiment. In FIG. 3, 31 to 38 are layers constituting the optical laminate 30, 31 is an adhesive layer, 32 is a resin layer, 33 is a hard coat layer, 34 is an adhesive layer, 35 is a glass layer, and 36 is a An adhesive layer having light scattering properties, 37 a resin layer, and 38 a hard coat layer. Since the adhesive layer 36 has light scattering properties, color shift and interference unevenness caused by the OLED display panel 100 are suppressed, and the OLED display device 300 has excellent visibility.
Note that in the OLED display device 300 shown in FIG. 3, an antireflection layer may be present on the visible side of the hard coat layer 38.

As another preferred embodiment of the present invention, in FIG. 2, the OLED display panel 100 has a color filter arranged on the viewing side, 21 is an adhesive layer, 22 is a resin layer, 23 is a hard coat layer, and 24 is an adhesive layer. 25 is an adhesive layer, 25 is a glass layer, 26 is an adhesive layer, 27 is a resin layer, 28 is a hard coat layer, there is no antireflection layer 29, and at least one of the adhesive layers 21, 24, and 26 is The pressure-sensitive adhesive layer has light-scattering properties, and the distance d (μm) between the pressure-sensitive adhesive layer having light-scattering properties and the color filter is 700 μm or less. By setting the distance d between the adhesive layer having light scattering properties and the color filter to be 700 μm or less, the light scattering layer is laminated to suppress color shift and interference unevenness caused by the OLED display device 300. Also, image blurring is less likely to occur and visibility is excellent. From the viewpoint of more efficiently reducing image blurring of an OLED display device due to lamination of light scattering layers, it is preferable that the distance between the adhesive layer having light scattering properties and the color filter is 600 μm or less. The thickness is preferably 500 μm or less, more preferably 500 μm or less, and most preferably the adhesive layer having light scattering properties is in direct contact with the color filter. OLED display devices 400A and 400B according to this embodiment are shown in FIGS. 4(a) and 4(b), respectively. In FIG. 4(a), 41A to 48A are layers constituting the optical laminate 40A, 41A is an adhesive layer, 42A is a resin layer, 43A is a hard coat layer, 44A is an adhesive layer, and 45A is a glass layer. , 46A is an adhesive layer having light scattering properties, 47A is a resin layer, and 48A is a hard coat layer. 15A is a color filter arranged on the visible side (upper side in FIG. 4A) of the OLED display panel 400B, and the distance d (μm) between the adhesive layer 46A having light scattering properties and the color filter 15A is is 700 μm or less. In FIG. 4(b), 41B to 48B are layers constituting the optical laminate 40B, 41B is an adhesive layer having light scattering properties, 42B is a resin layer, 43B is a hard coat layer, and 44B is an adhesive layer. , 45B is a glass layer, 46B is an adhesive layer, 47B is a resin layer, and 48B is a hard coat layer. 15B is a color filter arranged on the viewing side (upper side in FIG. 4(b)) of the OLED display panel 400B. Since the adhesive layer 41B having light scattering properties and the color filter 15B are in direct contact with each other, that is, the distance between the adhesive layer 41B having light scattering properties and the color filter 15B is 0 μm, the OLED display device Color shift and interference unevenness caused by 400B can be suppressed most efficiently.
Note that in the OLED display devices 400A and 400B shown in FIGS. 4A and 4B, an antireflection layer may be present on the visible side of the hard coat layers 48A and 48B.

As another preferred embodiment of the present invention, in FIG. 2, 21 is an adhesive layer, 22 is a resin layer, 23 is a hard coat layer, 24 is an adhesive layer, 25 is a glass layer, 26 is an adhesive layer, 27 is a resin layer, 28 is an anti-glare layer, and no anti-reflection layer 29 is present. FIG. 5 shows an OLED display device 500 according to this embodiment. In FIG. 5, 51 to 58 are layers constituting the optical laminate 50, 51 is an adhesive layer, 52 is a resin layer, 53 is a hard coat layer, 54 is an adhesive layer, 55 is a glass layer, and 56 is a The adhesive layer, 57 is a resin layer, and 58 is an anti-glare layer. Since the optical laminate 50 has the anti-glare layer 58, color shift and interference unevenness caused by the OLED display panel 100 are suppressed, and the OLED display device 500 has excellent visibility.
Note that in the OLED display device 500 shown in FIG. 5, an antireflection layer may be present on the viewing side of the antiglare layer 58.

As another preferred embodiment of the present invention, in FIG. 2, 21 is an adhesive layer, 22 is a resin layer, 23 is a hard coat layer, 24 is an adhesive layer, 25 is a glass layer, 26 is an adhesive layer, 27 is a resin layer, 28 is a hard coat layer, and an antireflection layer 29 is present. FIG. 6 shows an OLED display device 600 according to this embodiment. In FIG. 6, 61 to 69 are layers constituting the optical laminate 60, 61 is an adhesive layer, 62 is a resin layer, 63 is a hard coat layer, 64 is an adhesive layer, 65 is a glass layer, and 66 is a 67 is a resin layer, 68 is a hard coat layer, and 69 is an antireflection layer. Since the optical laminate 60 has the antireflection layer 69, interference unevenness caused by the OLED display panel 100 is suppressed, and the OLED display device 600 has excellent visibility.
In the OLED display device 600 shown in FIG. 6, 68 may be an anti-glare layer. In this embodiment, the anti-reflection function is further improved by laminating the anti-glare layer 68 and the anti-reflection layer 69.

As another preferred embodiment of the present invention, in FIG. 2, 21 is an adhesive layer, 22 is a resin layer, 23 is not present, 24 is an adhesive layer, 25 is a glass layer, 26 is an adhesive layer, 27 is a resin layer, 28 is a hard coat layer, and no antireflection layer 29 is present. Alternatively, in FIG. 2, 21 is an adhesive layer, 22 is a resin layer, 23 is a hard coat layer, 24 is an adhesive layer, 25 is a glass layer, 26 is an adhesive layer, 27 is a resin layer, and 28 is a hard coat layer. , and the antireflection layer 29 is not present. OLED display devices 700A and 700B according to this embodiment are shown in FIGS. 7(a) and 7(b), respectively. In FIG. 7(a), 71A, 72A, 74A to 78A are layers constituting the optical laminate 70A, 71A is an adhesive layer, 72A is a resin layer, 74A is an adhesive layer, 75A is a glass layer, and 76A is a resin layer. 77A is a resin layer, and 78A is a hard coat layer. Further, in FIG. 7(b), 71B to 78B are layers constituting the optical laminate 70B, 71B is an adhesive layer, 72B is a resin layer, 73B is a hard coat layer, 74B is an adhesive layer, and 75B is an adhesive layer. The glass layer, 76B is an adhesive layer, 77B is a resin layer, and 78B is a hard coat layer. In FIG. 7(a), the resin layer 72A and the glass layer 75A are bonded together by the adhesive layer 74A, or in FIG. 7(b), the glass layer 75B and the resin layer 77B are bonded by the adhesive layer 74A. By being bonded by the layer 76B, excellent impact resistance is imparted to each of the optical laminates 70A and 70B even if the optical laminates 70A and 70B do not have polarizing plates. Further, although the glass layer has excellent impact resistance, it is a material that is easily broken and has low flexibility. By bonding the glass layer and the resin layer with an adhesive layer, flexibility and bendability are improved, and the OLED display devices 700A and 700B can be used for flexible devices and foldable devices.
Note that in the OLED display devices 700A and 700B shown in FIGS. 7A and 7B, an antireflection layer may be present on the visible side of the hard coat layers 78A and 78B.

As another preferred embodiment of the present invention, in FIG. 2, 21 is an adhesive layer, 22 is a resin layer, 23 is a hard coat layer, 24 is an adhesive layer, 25 and 26 are absent, and 27 is a resin layer. The layer 28 is a hard coat layer, the antireflection layer 29 is not present, and one or both of the resin layers 22 and 27 is a transparent polyimide layer. FIG. 8 shows an OLED display device 800 according to this embodiment. In FIG. 8, 81 to 84, 87, and 88 are layers constituting the optical laminate 80, 81 is an adhesive layer, 82 is a transparent polyimide layer, 83 is a hard coat layer, 84 is an adhesive layer, and 87 is an adhesive layer. The resin layer 88 is a hard coat layer. In FIG. 8, the optical laminate 80 has a transparent polyimide layer 82 and a hard coat layer 83, thereby providing excellent impact resistance even when the optical laminate 80 does not have a polarizing plate. Furthermore, in this embodiment, the optical laminate 80 does not have a glass layer. Although the glass layer is a material that exhibits high hardness and excellent impact resistance, it has poor handling properties and is difficult to use for large displays used in PCs, tablets, and the like. By laminating a transparent polyimide layer and a hard coat layer, it is possible to achieve high hardness equivalent to that of a glass layer, and it also has excellent handling properties, so it can be applied to large displays used in PCs, tablets, etc.

In the embodiment shown in FIG. 8, it is preferable that an intermediate layer (compatible phase) be formed between the transparent polyimide layer 82 and the hard coat layer 83 (not shown). By forming an intermediate layer (compatible phase) between the transparent polyimide layer 82 and the hard coat layer 83, the adhesion between the transparent polyimide layer 82 and the hard coat layer 83 is improved. In that case, the shear fracture strength between the transparent polyimide layer 82 and the hard coat layer 83 is preferably 20 MPa or more.

In a preferred embodiment of the present invention, in FIG. 2, 21 is an adhesive layer, 22 is a resin layer, 23 is a hard coat layer, 24 is an adhesive layer, 25 is a glass layer, 26 is an adhesive layer, and 27 is an adhesive layer. The resin layer 28 is a hard coat layer, and the antireflection layer 29 is not present. FIG. 9 shows an OLED display device 900 according to this embodiment.

In FIG. 9, 900 is an OLED display device, 910 is an optical laminate, 91 is an adhesive layer, 92 is a resin layer, and 93 is an OLED display panel. The adhesive layer 91 and the resin layer 92 are layers that constitute the optical laminate 910.

Hereinafter, the present invention will be explained in more detail with reference to Examples. However, the present invention is not limited to the examples shown below.

[(meth)acrylic polymer A1]
A monomer mixture containing 99 parts by weight of butyl acrylate (BA) and 1 part by weight of 4-hydroxybutyl acrylate (HBA) was charged into a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser. . Furthermore, 0.1 part by weight of 2,2'-azobisisobutyronitrile (AIBN) as a polymerization initiator was added together with ethyl acetate to 100 parts by weight of the monomer mixture, and nitrogen gas was introduced while stirring gently. After replacing the flask with nitrogen, the temperature of the liquid in the flask was maintained at around 55°C and a polymerization reaction was carried out for 7 hours. Thereafter, ethyl acetate was added to the obtained reaction solution to prepare a solution of (meth)acrylic polymer A1 having a weight average molecular weight of 1.6 million, which was adjusted to a solid content concentration of 30%.

[(meth)acrylic polymer A2]
A solution of (meth)acrylic polymer A2 was prepared in the same manner as (meth)acrylic polymer A1, except that the monomers used were changed as shown in Table 1.

[Partially polymerized monomer syrup A3]
100 parts by weight of the monomer mixture shown in Table 1 and 0.05 parts by weight of the photopolymerization initiator 2,2-dimethoxy-1,2-diphenylethan-1-one (trade name "Omnirad 651", manufactured by IGM Resins BV) parts by weight and 0.05 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone (trade name "Omnirad 184", manufactured by IGM Resins BV) were put into a four-necked flask, and the viscosity was about 15 Pa under a nitrogen atmosphere. - Partially polymerized monomer syrup (partially polymerized product of monomer components) A3 was obtained by photopolymerizing by irradiating ultraviolet rays until s. The viscosity was measured using a B-type viscometer (BH viscometer No. 5 rotor manufactured by Tokyo Keiki Co., Ltd.) at a rotation speed of 10 rpm and a temperature of 30°C.

[Acrylic oligomer (oligomer B1)]
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, add 95 parts by weight of butyl acrylate (BA), 2 parts by weight of acrylic acid (AA), 3 parts by weight of methyl acrylate (MA), and polymerization. 0.1 part by weight of 2,2'-azobisisobutyronitrile and 140 parts by weight of toluene were charged as an initiator, and nitrogen gas was introduced while stirring gently to fully replace the nitrogen, and the liquid in the flask was A polymerization reaction was carried out for 8 hours while maintaining the temperature at around 70° C. to prepare an acrylic oligomer (oligomer B1) solution. The weight average molecular weight of the oligomer B1 was 4,500.

The abbreviations in Table 1 are as follows.
2EHA: 2-ethylhexyl acrylate BA: n-butyl acrylate LA: lauryl acrylate MA: methyl acrylate NVP: N-vinylpyrrolidone AA: acrylic acid HBA: 4-hydroxybutyl acrylate HEA: 2-hydroxyethyl acrylate
Omnirad 651: Photoinitiator, 2,2-dimethoxy-1,2-diphenylethan-1-one (manufactured by IGM Resins BV)
Omnirad 184: Photoinitiator, 1-hydroxy-cyclohexyl-phenyl-ketone (manufactured by IGM Resins BV)
AIBN: Azo polymerization initiator, 2,2'-azobisisobutyronitrile (manufactured by Kishida Chemical Co., Ltd.)

[Acrylic adhesive composition P1]
Per 100 parts by weight of the solid content of the (meth)acrylic polymer A1 solution, 0.01 part by weight of an isocyanate crosslinking agent (trade name: Takenate D110N, trimethylolpropane xylylene diisocyanate, manufactured by Mitsui Chemicals), peroxide 0.8 parts by weight of benzoyl peroxide (product name: Niper BMT, manufactured by NOF Corporation) as a crosslinking agent, 0.3 parts by weight of an acetoacetyl group-containing silane coupling agent (product name: A-100, manufactured by Soken Chemical Co., Ltd.) and 20 parts by weight of oligomer B1 to prepare an acrylic pressure-sensitive adhesive composition P1.

[Acrylic adhesive compositions P2 and P4]
Acrylic adhesive compositions P2 and P4 were prepared in the same manner as acrylic adhesive composition P1, except that the (meth)acrylic polymer, crosslinking agent, and additives used were changed as shown in Table 2. did.

[Acrylic adhesive composition P3]
As shown in Table 2, 1,6-hexanediol diacrylate (trade name "A-HD-N", manufactured by Shin Nakamura Chemical Co., Ltd., HDDA, polyfunctional monomer) was added to 100 parts by weight of partially polymerized monomer syrup A3. .3 parts by weight, and 0.1 weight of 2,2-dimethoxy-1,2-diphenylethan-1-one (trade name "Omnirad 651", manufactured by IGM Resins BV, photopolymerization initiator (additional initiator)) and 0.3 parts by weight of a silane coupling agent (trade name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.) were uniformly mixed to obtain an acrylic pressure-sensitive adhesive composition P3.

The abbreviations in Table 2 are as follows.
D110N: Trimethylolpropane/xylylene diisocyanate adduct (manufactured by Mitsui Chemicals, trade name: Takenate D110N)
A-HD-N: 1,6-hexanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name: A-HD-N)
Omnirad 651: Photoinitiator, 2,2-dimethoxy-1,2-diphenylethan-1-one (manufactured by IGM Resins BV)

(Example 1)
The acrylic adhesive composition P1 was uniformly coated with a fountain coater on the surface of a 75 μm thick polyethylene terephthalate film (separator) treated with a silicone release agent, and then heated in an air circulating constant temperature oven at 155° C. for 2 minutes. By drying, an adhesive layer with a thickness of 50 μm was produced. Next, a separator with an adhesive layer formed thereon was bonded to the surface (corona treated) of a 50 μm thick polyimide film (PI film, manufactured by DuPont Toray, Kapton 200V) to produce a PI film with an adhesive layer. .

Next, the separator was removed from the PI film with the adhesive layer, and it was bonded to a polyimide film (Upilex, manufactured by Ube Industries, Ltd., base material C1) having a thickness of 50 μm. Thereby, the laminate of Example 1 was obtained. Note that the base material corresponds to the resin layer of the present invention.

(Example 2)
A laminate of Example 2 was obtained in the same manner as Example 1, except that acrylic adhesive composition P2 was used instead of acrylic adhesive composition P1.

(Example 3)
Acrylic adhesive composition P3 was applied onto the release-treated surface of a release film (trade name "MRF #38", manufactured by Mitsubishi Plastics Co., Ltd.) so that the thickness after forming the adhesive layer was 50 μm. A pressure-sensitive adhesive composition layer was formed, and then a release film (trade name "MRN#38", manufactured by Mitsubishi Plastics Co., Ltd.) was laminated on the surface of the pressure-sensitive adhesive composition layer. Thereafter, UV irradiation was performed under the conditions of illuminance: 4 mW/cm ² and light intensity: 1200 mJ/cm ² to photocure the adhesive composition layer, thereby forming an adhesive layer. Then, an adhesive layer was obtained in which both sides of the adhesive layer were protected by release films. Next, one side of the release film that protects the adhesive layer was peeled off, and the adhesive layer was formed on the surface (corona treated) of a 50 μm thick polyimide film (PI film, manufactured by DuPont Toray, Kapton 200V). The films were joined to produce a PI film with an adhesive layer.

Next, the release film was removed from the PI film with the adhesive layer, and it was bonded to a polyimide film (Upilex, manufactured by Ube Industries, Ltd., base material C1) having a thickness of 50 μm. Thereby, a laminate of Example 3 was obtained.

(Example 4)
A laminate of Example 4 was obtained in the same manner as Example 1, except that acrylic adhesive composition P4 was used instead of acrylic adhesive composition P1.

(Example 5)
The laminate of Example 6 was produced in the same manner as in Example 1, except that a 30 μm thick polyimide film (Neoplym L-AJFF-50, manufactured by Mitsubishi Gas Chemical Co., Ltd., base material C2) was used in place of the base material C1. I got it.

(Example 6)
A laminate of Example 6 was obtained in the same manner as Example 1, except that a 55 μm thick cycloolefin polymer film (Nippon Zeon Co., Ltd. ZF16, base material C3) was used in place of the base material C1. .

[evaluation]
<Weight average molecular weight (Mw) of (meth)acrylic polymer and acrylic oligomer>
The weight average molecular weight (Mw) of the obtained (meth)acrylic polymer and acrylic oligomer was measured by GPC (gel permeation chromatography).
・Analyzer: Tosoh Corporation, HLC-8120GPC
・Column: Manufactured by Tosoh Corporation, G7000H _XL +GMH _XL +GMH _XL
・Column size: 7.8mmφ each x 30cm total 90cm
・Column temperature: 40℃
・Flow rate: 0.8ml/min
・Injection volume: 100μl
・Eluent: Tetrahydrofuran ・Detector: Differential refractometer (RI)
・Standard sample: polystyrene

<Thickness>
The thickness of the base material (resin layer), adhesive layer, etc. was measured using a dial gauge (manufactured by Mitutoyo).

<Thermomechanical analysis>
Thermomechanical analysis was performed on each of the base materials C1 to C3. In the thermomechanical analysis, the temperature of the base material was raised from 20°C to 85°C at a heating rate of 10°C/min. The temperature of the substrate was maintained at 85°C from when the temperature of the substrate reached 85°C until the end of the thermomechanical analysis. The dimensional change rate D1 of the base material in the MD direction was measured when the temperature of the base material reached 85°C. Furthermore, the dimensional change rate D2 in the MD direction of the base material was measured after the temperature of the base material reached 85 °C and was maintained at 85 °C for 5 hours. Details of the thermomechanical analysis are as follows. The dimensional change rates D1 and D2 of the PI film (manufactured by DuPont-Toray, Kapton 200V) used in each laminate were both 0.12%.
Equipment: TMA Q-400 manufactured by TA Instruments
Measurement mode: Tension Measurement load: 0.98mN
Atmosphere gas: _N2
Temperature conditions: 20°C → 85°C (heating rate 10°C/min), 85°C x 300min
Sample size: Width 4mm (TD) x Height approx. 16mm (MD)

<Gel fraction of adhesive layer>
A first sample was obtained by scraping off about 0.2 g from the pressure-sensitive adhesive layer one week after it was prepared. The first sample was wrapped in a Teflon (registered trademark) film (trade name: "NTF1122", manufactured by Nitto Denko Corporation) having a diameter of 0.2 μm, and then tied with a kite string, and this was used as a second sample. The weight of the second sample was measured before being subjected to the following test, and this was defined as weight A. Note that the weight A is the total weight of the first sample (adhesive layer), the Teflon (registered trademark) film, and the kite string. Moreover, the total weight of the Teflon (registered trademark) film and the kite string was defined as weight B. Next, the second sample was placed in a 50 ml container filled with ethyl acetate and allowed to stand at 23°C for one week. Thereafter, the second sample was taken out from the container and dried in a dryer at 130° C. for 2 hours to remove ethyl acetate, and then the weight of the second sample was measured. The weight of the second sample after being subjected to the test was measured, and this was defined as weight C. Then, the gel fraction (weight %) was calculated from the following formula.
Gel fraction (wt%) = (CB)/(AB) x 100

<Creep amount Cr ₇₀ at 70°C>
The creep amount Cr ₇₀ at 70° C. of the prepared adhesive layer was evaluated by the method described above. As the support film 105, a PET film with a thickness of 50 μm was used. As the test plate 107, a SUS304 plate (30 mm x 75 mm, thickness 2.5 mm) was used. As a laser displacement meter, LK-H057 manufactured by Keyence Corporation was used. Further, the test plate 107 was left in an atmosphere at 70° C. for 5 minutes after it was held vertically with the test plate 107 facing upward and before the test was started.

<Modulus>
The 500% modulus of the prepared adhesive layer was evaluated by the method described above. Autograph AG-IS manufactured by Shimadzu Corporation was used as a tensile tester.

<Bending resistance (continuous bending) test method>
FIG. 13 shows a schematic diagram of a bending test based on a U-shaped stretch tester (manufactured by Yuasa System Equipment Co., Ltd.). The U-shaped expansion/contraction testing machine has a mechanism that repeatedly bends a sheet workpiece 180° into a U-shape without any load in a constant temperature chamber.By adjusting the distance between the surfaces bent into a U-shape, Diameter can be changed. The sample 132 (2.5 cm x 10 cm) of the laminate obtained in Examples 1 and 2 was set in a testing machine so that it could be bent in the long side direction at the bending point P. Sample 132 was fixed with double-sided adhesive tape 131. The test was conducted under the conditions of 60° C., 95% RH, bending angle of 180°, bending diameter of 3 mm, and bending speed of 1 second/time.

In addition, in the sample 132, evaluation was performed by bending the sample 132 in the long side direction near the center so that the base material C1 was on the concave side (inside). The bending strength of Sample 132 was evaluated based on the number of times until interlayer peeling occurred at the bent portion. Here, when the number of bending reached 200,000 times, the test was discontinued. Evaluation was performed based on the following criteria.
〇: No defects after 200,000 times or more ×: Peeling after less than 200,000 times

<Bending angle and bending marks>
Using the above testing machine, sample 132 of the laminate obtained in each example and comparative example was bent from an initial flat state (bending angle of 0°) to a bending angle of 180° with a predetermined bending diameter. It was kept at ℃ for 72 hours. At this time, the measurement sample 132 was bent in the long side direction near the center so that the base materials C1 to C5 were on the concave side (inside). In the base material, the direction perpendicular to the fold line of sample 132 was the same as the measurement direction (MD direction) of the base material in thermomechanical analysis. After that, the sample 132 is returned to the initial position (flat), removed from the test machine, and left at 25°C for 5 minutes without any external load applied to the bending direction of the sample 132.The bending angle remaining in the sample 132 is was measured. Furthermore, the bending marks of sample 132 were evaluated based on the following criteria.
○: When it is returned flat, the crease mark is almost invisible (no problem in practical use)
△: Slight creases are visible when flattened (no practical problem)
×: When it is returned flat, the crease marks are clearly visible (there is a practical problem)

As can be seen from Table 3, the laminates of Examples 1 to 6 are a combination of a base material (resin layer) with a D1-D2 value of 0.4 or less and an adhesive layer with a creep amount Cr ₇₀ of 200 μm or less. had practically sufficient bending recovery properties.

The optical laminate for OLED display devices of the present invention can be suitably used for image display devices such as flexible liquid crystal display devices, organic EL display devices, and electronic paper.

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 colored layer 15G Green colored layer 15B Blue colored layer 16 Black matrix layer W External light G Reflected light C1 First optical path (direct light)
C2 Second optical path (reflected light)
17 Bonding layer 200 OLED display device 20 Optical laminate 21 Adhesive layer or adhesive layer 22 Resin layer, glass layer or shock absorption layer 23 Hard coat layer or anti-glare layer 24 Adhesive layer or adhesive layer 25 Resin layer, glass layer or shock absorption layer 26 Adhesive layer or adhesive layer 27 Resin layer, glass layer or shock absorption layer 28 Hard coat layer or anti-glare layer 29 Antireflection layer 300 OLED display device 30 Optical laminate 31 Adhesive layer 32 Resin layer 33 Hard coat layer 34 Adhesive layer 35 Glass layer 36 Adhesive layer having light scattering properties 37 Resin layer 38 Hard coat layer 400A OLED display device 40A Optical laminate 41A Adhesive layer 42A Resin layer 43A Hard coat layer 44A Adhesive layer 45A Glass layer 46A Adhesive layer with light scattering properties 47A Resin layer 48A Hard coat layer 15A Color filter 400B OLED display device 40B Optical laminate 41B Adhesive layer with light scattering properties 42B Resin layer 43B Hard coat layer 44B Adhesive layer 45B Glass layer 46B Adhesive layer 47B Resin layer 48B Hard coat layer 15B Color filter 500 OLED display device 50 Optical laminate 51 Adhesive layer 52 Resin layer 53 Hard coat layer 54 Adhesive layer 55 Glass layer 56 Adhesive layer 57 Resin layer 58 Anti-glare layer 600 OLED display device 60 Optical laminate 61 Adhesive layer 62 Resin layer 63 Hard coat layer 64 Adhesive layer 65 Glass layer 66 Adhesive layer 67 Resin layer 68 Hard coat layer 69 Antireflection layer 700A OLED display device 70A Optical laminate 71A Adhesive layer 72A Resin layer 74A Adhesive layer 75A Glass layer 76A Adhesive layer 77A Resin layer 78A Hard coat layer 700B OLED display device 70B Optical laminate 71B Adhesive layer 72B Resin layer 73B Hard coat layer 74B Adhesive Layer 75B Glass layer 76B Adhesive layer 77B Resin layer 78B Hard coat layer 800 OLED display device 80 Optical laminate 81 Adhesive layer 82 Transparent polyimide layer 83 Hard coat layer 84 Adhesive layer 87 Resin layer 88 Hard coat layer 900 OLED display device 910 Optical laminate 91 Adhesive layer 92 Resin layer 93 OLED display panel 104 Adhesive layer 105 Support film 106 Test piece 107 Stainless steel test plate 108 Load 111 Optical laminate 112a Support 112b Support 113 Spacer 114 Fixture 131 Double-sided adhesive Tape 132 Sample of laminate 300 OLED display device 142 Resin layer 140a Rigid part 140b Rigid part 141 Flexible part 143 Inner surface 144 Outer surface 145 Roller

Claims (1)

An optical laminate for an OLED display device having a resin layer and an adhesive layer,
The dimensional change rate D1 (%) of the resin layer from room temperature to 85°C and the dimensional change rate D2 (%) of the resin layer after being maintained at 85°C for 5 hours after reaching 85°C are as follows. satisfies formula (A),
An optical laminate for an OLED display device, wherein the adhesive layer has a creep amount Cr ₇₀ of 200 μm or less as determined by the following test at 70°C.
Test: A test piece having an adhesive layer of 20 mm in length x 30 mm in width is placed on one end of a stainless steel test plate, and the bonding surface between the test plate and the adhesive layer is 20 mm in length x 20 mm in width, and Attach it so that it protrudes 10 mm horizontally from the part. With the test plate fixed so that one end to which the test piece is not bonded is vertically upward and one end to which the test piece is bonded is vertically downward, a weight is fixed to the center of the lower end of the test piece to give a weight of 500gf. Apply a load vertically downward. The amount of creep (amount of deviation) of the adhesive layer relative to the test plate 3600 seconds after the start of applying the load is measured.
D1-D2≦0.4 (A)

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