Photocurable adhesive sheet

Abstract

The present invention aims to provide an adhesive sheet suitable for manufacturing self-emissive display devices such as mini / micro LED display devices that prevent reflections from metal wiring, improve contrast, and possess excellent height difference absorption and processability. The photocurable adhesive sheet of the present invention is characterized by comprising an adhesive layer cured by radiation irradiation, the adhesive layer containing a colorant, the maximum transmittance of the adhesive layer at wavelengths of 200–400 nm being greater than the maximum transmittance at wavelengths of 400–700 nm, the storage modulus (G'b85) of the adhesive layer before curing at 85°C being less than 65 kPa, and the storage modulus (G'a10) of the adhesive layer after curing at 10°C satisfying the following relationship (1) with the storage modulus (G'b85) of the adhesive layer before curing at 85°C. 3.3 <G'a10 / G'b85(1)。

Description

Technical Field

[0001] This invention relates to photocurable adhesive sheets. More specifically, it relates to photocurable adhesive sheets suitable for sealing light-emitting elements of self-emissive display devices such as mini / micro LEDs. Background Technology

[0002] In recent years, as a next-generation display device, self-emissive display devices, represented by mini / microlight emitting diode displays, have been designed. Mini / microlight emitting diode displays, as their basic structure, use a substrate with a high density of numerous tiny LED light-emitting elements (LED chips) as the display panel. These LED chips are sealed with a sealing material, and a resin film, glass plate, or other covering components are laminated on the outermost layer.

[0003] In self-emissive display devices such as mini / micro LED display devices, there are several types, including white backlight, white light-emitting filter, and RGB. In the white light-emitting filter and RGB types, an adhesive colored black is sometimes used as a sealing material (see, for example, Patent Documents 1-3).

[0004] This is because the aforementioned black adhesive contributes to preventing color mixing and improving contrast by filling the spaces between the RGB LED chips arranged on the substrate of the display panel. In addition, it can prevent reflections from metal wiring, metal oxides such as ITO, etc., disposed on the substrate of the display panel.

[0005] In miniature / micro-LED displays, LED chips are densely packed onto a substrate, with numerous minute height differences between them. For the sealing materials used in miniature / micro-LED displays, excellent height difference absorption (also known as "height difference following") is required to fill these height differences. Therefore, to improve height difference absorption, the aforementioned black adhesive needs to be designed to exhibit high fluidity.

[0006] On the other hand, while adhesives exhibiting high fluidity have excellent absorption properties, they also suffer from reduced processability, such as reduced shape stability and handling. For example, laminates with highly fluid adhesive layers are prone to problems such as insufficient adhesive during cutting, overflow and sagging of the adhesive layer from the ends during storage, and sometimes foreign matter adhering to the overflowed adhesive layer, leading to process contamination.

[0007] As an adhesive that combines the aforementioned height difference absorption and processability, a light-curing adhesive (hybrid adhesive) is known (see, for example, Patent Document 4). Hybrid adhesives have the following advantages: firstly, they have high fluidity, are made into a semi-cured state with excellent height difference absorption to fully follow the height difference, and then are cured by light, which improves processability.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2019-204905

[0011] Patent Document 2: Japanese Patent Application Publication No. 2017-203810

[0012] Patent Document 3: Japanese Patent Publication No. 2018-523854

[0013] Patent Document 4: International Publication No. WO2016 / 170875 Summary of the Invention

[0014] The problem the invention aims to solve

[0015] However, when coloring is achieved by blending carbon black or other substances into a mixed adhesive, light cannot pass through the adhesive, which results in problems such as inhibited curing and difficulty in improving processability.

[0016] This invention was developed based on the situation described above. The purpose of this invention is to provide an adhesive sheet that is suitable for manufacturing self-emissive display devices such as mini / micro LED display devices that improve the function of preventing reflections from metal wiring and have improved contrast, and also has excellent height difference absorption and processability.

[0017] Solution for solving the problem

[0018] In order to achieve the aforementioned objectives, the inventors conducted in-depth research and discovered that by coloring the adhesive layer of the photocurable adhesive sheet in a manner that exhibits absorption in the visible light region but high transmittance in the ultraviolet region, the reflection prevention function of metal wiring and the like in self-emissive display devices is improved, as is the contrast ratio, while also achieving excellent height difference absorption and processability. The present invention was made based on these insights.

[0019] A first aspect of the present invention provides a photocurable adhesive sheet. Specifically, the photocurable adhesive sheet of the first aspect of the present invention comprises an adhesive layer that is cured by radiation. In the photocurable adhesive sheet of the first aspect of the present invention, the adhesive layer before curing is in a highly fluid semi-cured state, exhibiting excellent height difference absorption. Therefore, when bonded to a display panel with densely arranged light-emitting elements (LED chips), it fully follows the minute height differences between the light-emitting elements (LED chips), thereby achieving a tight seal without air bubbles or gaps. On the other hand, the cured adhesive layer exhibits excellent processability. Therefore, when cutting the laminate containing the cured adhesive layer, the occurrence of missing adhesive can be suppressed, and during storage, the overflow and sagging of the adhesive layer from the ends can be suppressed.

[0020] In the photocurable adhesive sheet of the first side of the present invention, the maximum transmittance of the aforementioned adhesive layer at wavelengths of 200-400 nm is greater than the maximum transmittance at wavelengths of 400-700 nm. The aforementioned adhesive layer has high absorption of visible light (wavelength 400-700 nm) and excellent light-shielding properties. This excellent light-shielding property of the aforementioned adhesive layer is preferred from the following aspects: the adhesive layer, which fills the fine height differences between LED chips without gaps, prevents reflections caused by metal wiring on the display panel, prevents color mixing between the arranged light-emitting elements (LED chips), and improves contrast. On the other hand, the aforementioned adhesive layer has high transmittance of ultraviolet light (wavelength 200-400 nm). This excellent ultraviolet transmittance of the aforementioned adhesive layer is preferred from the aspect that the processability of the adhesive layer is improved by curing it by irradiating it with ultraviolet light. That is, the configuration in which the maximum transmittance of the aforementioned adhesive layer at wavelengths of 200–400 nm is greater than the maximum transmittance at wavelengths of 400–700 nm is preferred from the perspective of balancing excellent light shielding for visible light and curing reaction based on ultraviolet irradiation.

[0021] The adhesive layer in the photocurable adhesive sheet of the first side of the present invention comprises a colorant. The colorant is preferably one whose maximum transmittance at wavelengths of 200–400 nm is greater than the maximum transmittance at wavelengths of 400–700 nm. This configuration is preferred from the viewpoint that the adhesive layer achieves a maximum transmittance at wavelengths of 200–400 nm greater than the maximum transmittance at wavelengths of 400–700 nm.

[0022] In the photocurable adhesive sheet of the first side of the present invention, the storage modulus (G'b85) of the aforementioned adhesive layer before curing is less than 65 kPa at 85°C. This configuration is preferred from the perspective that the aforementioned adhesive layer before curing exhibits excellent height difference absorption.

[0023] In the photocurable adhesive sheet of the first side of the present invention, the storage modulus (G'a10) of the cured adhesive layer at 10°C and the storage modulus (G'b85) of the uncured adhesive layer at 85°C satisfy the following relationship (1).

[0024] 3.3 <G'a10 / G'b85 (1)

[0025] This configuration is preferred in that the aforementioned adhesive layer exhibits excellent height difference absorption before curing and excellent processability after curing.

[0026] In the photocurable adhesive sheet of the first side of the present invention, the curing based on the aforementioned radiation irradiation is preferably based on a cumulative light intensity of 3000 mJ / cm. 2 The curing is carried out by ultraviolet light. This composition is preferred in that the aforementioned adhesive layer cures by ultraviolet light and exhibits excellent processability.

[0027] In the photocurable adhesive sheet of the first side of the present invention, the storage modulus (G'a10) of the cured adhesive layer at 10°C is preferably 90 kPa or more. This configuration is preferred from the viewpoint that the cured adhesive layer exhibits excellent processability.

[0028] In the photocurable adhesive sheet of the first side of the present invention, the aforementioned adhesive layer preferably contains a base polymer, a crosslinking agent, and a photopolymerization initiator. In this configuration, the aforementioned base polymer preferably contains an acrylic polymer. Furthermore, in this case, the aforementioned crosslinking agent preferably contains a polyfunctional (meth)acrylate. These configurations are preferred from the perspective that the aforementioned adhesive layer forms a crosslinked structure and cures through a reaction between the crosslinking agent and the photopolymerization initiator based on radiation irradiation, thereby exhibiting excellent processability. It should be noted that in this configuration, the aforementioned adhesive layer constitutes a mixed adhesive, and the aforementioned base polymer is a substance with excellent semi-curing to high-gradient absorption properties.

[0029] In the photocurable adhesive sheet of the first side of the present invention, the aforementioned adhesive layer is preferably configured as a single layer formed of the aforementioned base polymer, having two opposing main surfaces, wherein when the aforementioned single-layer adhesive layer is divided into two equal parts along the thickness direction, the concentration of the aforementioned crosslinking agent and / or the aforementioned photopolymerization initiator in the region belonging to one of the aforementioned two main surfaces, namely the first main surface, is different from the concentration of the aforementioned crosslinking agent and / or the aforementioned photopolymerization initiator in the region belonging to the other, namely the second main surface. In this configuration, the aforementioned single-layer adhesive layer preferably has a concentration gradient of the aforementioned crosslinking agent and / or the aforementioned photopolymerization initiator in the thickness direction.

[0030] These photocurable adhesive sheets are preferably manufactured by a method that includes the following steps.

[0031] An adhesive layer is formed from the aforementioned base polymer,

[0032] Allow the aforementioned adhesive layer to cure.

[0033] Prepare a solution of the aforementioned crosslinking agent and / or the aforementioned photopolymerization initiator.

[0034] The aforementioned solution is applied to one side of the cured adhesive layer, allowing the aforementioned crosslinking agent and / or the aforementioned photopolymerization initiator contained in the solution to penetrate from the aforementioned one side of the adhesive layer along the thickness direction.

[0035] Allow the aforementioned adhesive layer to dry.

[0036] The above configuration involves coating one side of the adhesive layer with a solution of the aforementioned crosslinking agent and / or the aforementioned photopolymerization initiator and allowing it to penetrate, thereby creating a concentration difference between the crosslinking agent and / or the aforementioned photopolymerization initiator on the front and back sides of the adhesive layer. This configuration is preferred from the perspective of achieving excellent height difference absorption of the aforementioned adhesive layer before curing and excellent processability of the aforementioned adhesive layer after curing.

[0037] Furthermore, in the photocurable adhesive sheet of the first side of the present invention, the aforementioned adhesive layer preferably contains a polymer having a benzophenone structure in its side chains. In this configuration, the aforementioned adhesive layer is preferably a cured product of an adhesive composition containing an olefinically unsaturated compound and a polymer having a benzophenone structure in its side chains. This configuration is preferred from the aspects that the aforementioned adhesive layer before curing exhibits excellent height difference absorption, that the aforementioned benzophenone structure is cross-linked and cured by ultraviolet irradiation, and that excellent processability is achieved.

[0038] Furthermore, a second aspect of the present invention provides a self-emissive display device comprising: a display panel having a plurality of light-emitting elements arranged on one side of a substrate, and a photocurable adhesive sheet as described in the first aspect of the present invention. The light-emitting elements of the display panel are sealed by an adhesive layer of the photocurable adhesive sheet, and the adhesive layer is cured. In the self-emissive display device of the second aspect of the present invention, the display panel may be an LED panel having a plurality of LED chips arranged on one side of a substrate. This configuration is preferred in that, in the self-emissive display device of the second aspect of the present invention, the adhesive layer, which fills the fine height differences between the light-emitting elements (LED chips) without gaps and has excellent light-shielding properties, can prevent reflections from metal wiring on the substrate, prevent RGB color mixing, and improve contrast.

[0039] The self-emissive display device of the second aspect of the present invention described above can be manufactured by a method comprising the following steps.

[0040] The process of laminating an adhesive layer of a photocurable adhesive sheet of the first side of the present invention onto a display panel having multiple light-emitting elements arranged on one side of a substrate, and sealing the aforementioned light-emitting elements using the adhesive layer; and

[0041] The process of curing the aforementioned adhesive layer by irradiating it with radiation.

[0042] Because the aforementioned adhesive layer before curing has excellent height difference absorption, it can fully follow the minute height differences between the light-emitting elements, thus achieving a tight seal without leaving air bubbles or gaps. Furthermore, curing the aforementioned adhesive layer by irradiating it with radiation results in excellent processability.

[0043] The aforementioned radiation is preferably ultraviolet light that is transmissible through the aforementioned adhesive layer.

[0044] The effects of the invention

[0045] The photocurable adhesive sheet of the present invention has an adhesive layer with high visible light shielding and excellent height difference absorption. Therefore, when used in the manufacture of self-emissive display devices, it fills the height difference between multiple light-emitting elements without gaps, preventing reflections from metal wiring, suppressing color mixing between multiple light-emitting elements, and improving contrast. Furthermore, by curing the adhesive layer, which has excellent ultraviolet transmittance, by irradiating it with radiation, processability is improved. During cutting, adhesive defects are suppressed, and during storage, overflow and sagging of the adhesive layer from the ends are prevented. Therefore, by using the photocurable adhesive sheet of the present invention in the manufacture of self-emissive display devices, it is possible to efficiently manufacture self-emissive display devices with improved protection against reflections from metal wiring and the like, and improved contrast. Attached Figure Description

[0046] Figure 1 A cross-sectional view illustrating one embodiment of the photocurable adhesive sheet of the present invention is shown.

[0047] Figure 2 A cross-sectional view illustrating the steps of one embodiment of a method for manufacturing a photocurable adhesive sheet for carrying out the present invention.

[0048] Figure 3 A cross-sectional view illustrating one embodiment of the photocurable adhesive sheet of the present invention is shown.

[0049] Figure 4 This is a schematic diagram (cross-sectional view) illustrating one embodiment of the self-emissive display device (mini / micro LED display device) of the present invention.

[0050] Figure 5This is a schematic diagram (cross-sectional view) illustrating one embodiment of a method for manufacturing a self-emissive display device (mini / micro LED display device) for carrying out the present invention. Detailed Implementation

[0051] The embodiments of the present invention will be described with reference to the accompanying drawings as needed, but the present invention is not limited thereto, and is merely an example.

[0052] [Light-curable adhesive sheet]

[0053] The photocurable adhesive sheet of the first side of the present invention includes an adhesive layer that is cured by radiation. The adhesive layer includes a colorant. The maximum transmittance of the adhesive layer at wavelengths of 200 to 400 nm is greater than the maximum transmittance at wavelengths of 400 to 700 nm. The storage modulus (G'b85) of the adhesive layer before curing at 85°C is less than 65 kPa. The storage modulus (G'a10) of the adhesive layer after curing at 10°C and the storage modulus (G'b85) before curing at 85°C satisfy the following relationship (1).

[0054] 3.3 <G'a10 / G'b85 (1)

[0055] In this specification, the photocurable adhesive sheet of the first side of the present invention described above is sometimes simply referred to as "photocurable adhesive sheet A". In addition, in this specification, the adhesive layer that satisfies the following (a) to (d) is sometimes referred to as "adhesive layer A".

[0056] (a) Cured by radiation.

[0057] (b) The maximum transmittance at wavelengths of 200–400 nm is greater than the maximum transmittance at wavelengths of 400–700 nm.

[0058] (c) The energy storage modulus (G'b85) at 85°C before curing is less than 65 kPa.

[0059] (d) The storage modulus at 10°C after curing (G'a10) and the storage modulus at 85°C before curing (G'b85) satisfy the following relationship (1).

[0060] 3.3 <G'a10 / G'b85 (1)

[0061] "Adhesive sheet" is considered to include the meaning of "adhesive tape". That is, the light-curable adhesive sheet A can be an adhesive tape in the form of a strip.

[0062] The shape of the photocurable adhesive sheet A is not particularly limited as long as it has an adhesive surface formed by the surface of the adhesive layer A. The photocurable adhesive sheet A can be a single-sided adhesive sheet with only one side as the adhesive surface, or it can be a double-sided adhesive sheet with both sides as the adhesive surface. When the photocurable adhesive sheet A is a double-sided adhesive sheet, it can have a shape in which both adhesive surfaces are provided by the adhesive layer A, or it can have a shape in which one adhesive surface is provided by the adhesive layer A and the other adhesive surface is provided by an adhesive layer other than the adhesive layer A. From the viewpoint of bonding the objects to be bonded together, a double-sided adhesive sheet is preferred, and a double-sided adhesive sheet in which both sides of the sheet are the surfaces of the adhesive layer A is more preferred.

[0063] The photocurable adhesive sheet A can be an adhesive sheet without a substrate (substrate layer), i.e., a so-called "substrate-free type" adhesive sheet (sometimes called "substrate-free adhesive sheet"), or an adhesive sheet with a substrate (sometimes called "substrate-supported adhesive sheet"). Examples of substrate-free adhesive sheets in this invention include: double-sided adhesive sheets consisting only of adhesive layer A, and double-sided adhesive sheets formed by adhesive layer A and other adhesive layers (adhesive layers other than adhesive layer A). Examples of substrate-supported adhesive sheets in this invention include: single-sided adhesive sheets having adhesive layer A on one side of the substrate, double-sided adhesive sheets having adhesive layer A on both sides of the substrate, and double-sided adhesive sheets having adhesive layer A on one side of the substrate and other adhesive layers on the other side.

[0064] Of the above, from the viewpoint of improving optical properties, a substrate-free adhesive sheet is preferred, and a substrate-free double-sided adhesive sheet consisting only of adhesive layer A is more preferred. Furthermore, while there are no particular limitations when adhesive sheet A is an adhesive sheet with a substrate, from the viewpoint of processability, a double-sided adhesive sheet with adhesive layer A on both sides of the substrate is preferred (a substrate-bearing double-sided adhesive sheet).

[0065] It should be noted that the "substrate (substrate layer)" mentioned above refers to the part that is bonded to the substrate (optical component, etc.) together with the adhesive layer when the photocurable adhesive sheet A is used (bonded) to the substrate, excluding the release film (release film) that is peeled off during the use (bonding) of the adhesive sheet.

[0066] As described above, the photocurable adhesive sheet A can be an adhesive sheet with a substrate. Examples of such substrates include various optical films such as plastic films, anti-reflective (AR) films, polarizing plates, and retardation plates. Examples of raw materials for the aforementioned plastic films include polyester resins such as polyethylene terephthalate (PET), acrylic resins such as polymethyl methacrylate (PMMA), polycarbonate, triacetyl cellulose (TAC), polysulfone, polyarylate, polyimide, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, ethylene-propylene copolymer, and cyclic olefin polymers such as "Arton" (a cyclic olefin polymer manufactured by JSR Corporation) and "ZEONOR" (a cyclic olefin polymer manufactured by Zeon Corporation). It should be noted that these plastic materials can be used alone or in combination of two or more.

[0067] The aforementioned substrate is preferably transparent. The total transmittance of the substrate in the visible light wavelength region (according to JIS K7361-1) is not particularly limited, but is preferably 85% or more, more preferably 88% or more. Furthermore, the haze of the substrate (according to JIS K7136) is not particularly limited, but is preferably 1.5% or less, more preferably 1.0% or less. Examples of such transparent substrates include PET films, non-oriented films such as those with the trade names "Arton" and "ZEONOR".

[0068] The thickness of the aforementioned substrate is not particularly limited, but is preferably 12–75 μm. It should be noted that the aforementioned substrate can have any shape, whether single-layer or multi-layer. In addition, the surface of the aforementioned substrate can be appropriately subjected to commonly known surface treatments, such as anti-reflective treatment (AR treatment), anti-glare treatment, corona discharge treatment, plasma treatment, and chemical treatment, such as primer treatment.

[0069] As described above, the photocurable adhesive sheet A may have other adhesive layers (adhesive layers other than adhesive layer A). There are no particular limitations on these other adhesive layers; examples include adhesive layers formed from commonly known adhesives such as urethane adhesives, acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, epoxy adhesives, vinyl alkyl ether adhesives, and fluorinated adhesives. It should be noted that two or more of the above adhesives may be used alone or in combination.

[0070] In addition to adhesive layer A, substrate, and other adhesive layers, the photocurable adhesive sheet A may also have other layers (e.g., intermediate layer, primer layer, etc.) without impairing the effect of the present invention.

[0071] A release film (isolation film) can be provided on the adhesive surface of the photocurable adhesive sheet A until use. The form in which the adhesive surface of the photocurable adhesive sheet A is protected by the release film is not particularly limited; it can be a form where two release films protect each adhesive surface, or it can be a form where it is rolled into a roll and a single release film with both sides as the release surface protects each adhesive surface. The release film serves as a protective material for the adhesive layer and is peeled off when bonded to the substrate. It should be noted that in the photocurable adhesive sheet A, the release film also functions as a support for the adhesive layer. It should also be noted that the release film may or may not be necessary.

[0072] Figure 1 A cross-sectional view illustrating one embodiment of the photocurable adhesive sheet A of the present invention is shown. Figure 1 In the diagram, 1A is the photocurable adhesive sheet of the present invention, 10 is the adhesive layer, and S1 and S2 are the support bodies (including the release film).

[0073] The thickness (total thickness) of the photocurable adhesive sheet A is not particularly limited, but is preferably 10 μm to 1 mm, more preferably 100 to 500 μm, and even more preferably 150 to 350 μm. By making the thickness 10 μm or more, the adhesive layer A can easily follow the height difference portion, thereby improving the height difference absorption. It should be noted that the thickness of the photocurable adhesive sheet A does not include the thickness of the release film.

[0074] The photocurable adhesive sheet A has the aforementioned adhesive layer A, and therefore has light absorption properties for visible light. The total light transmittance of the photocurable adhesive sheet A is, for example, 80% or less, or may be 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less.

[0075] Because the photocurable adhesive sheet A has an adhesive layer A, it exhibits excellent height difference absorption before curing. For example, it has excellent height difference absorption even for height differences exceeding 40 μm, in addition to height differences of 5–10 μm. Furthermore, it also exhibits height difference absorption for height differences exceeding 80 μm.

[0076] In addition, since the photocurable adhesive sheet A has an adhesive layer A, it has excellent processability after curing, which can suppress the lack of adhesive during cutting, the overflow of the adhesive layer from the end during storage, and sagging.

[0077] Furthermore, since the photocurable adhesive sheet A has an adhesive layer A, its bonding reliability is also excellent.

[0078] (Adhesive layer A)

[0079] Adhesive layer A is cured by irradiation with radiation. For example, after a photocurable adhesive sheet A is pasted onto an object, irradiating the adhesive sheet with radiation causes adhesive layer A to cure. Before curing, adhesive layer A is in a highly fluid state and has excellent height difference absorption, for example, it can seal the minute height difference between the metal wiring layer and the light-emitting element (LED chip) of a self-emissive display device (mini / micro LED display device) without gaps. In addition, the processability of adhesive layer A after curing by radiation irradiation is improved, and it can suppress insufficient adhesive during cutting, overflow of the adhesive layer from the ends during storage, and sagging.

[0080] Examples of radiation used for curing include ionizing radiation such as alpha rays, beta rays, gamma rays, X-rays, neutron rays, and electron rays, as well as ultraviolet radiation. Since adhesive layer A exhibits ultraviolet transmittance, ultraviolet radiation is preferred. More preferably, ultraviolet radiation with a wavelength of 200–400 nm, and even more preferably, ultraviolet radiation with a wavelength of 330–400 nm. Examples of light sources for ultraviolet irradiation include high-pressure mercury lamps, low-pressure mercury lamps, microwave excitation lamps, metal halide lamps, chemical lamps, black light lamps, or LEDs. Furthermore, the irradiation energy, irradiation time, and irradiation method of the curing radiation can be appropriately set as long as the adhesive layer A is cured without adversely affecting the adhered material. For example, when ultraviolet radiation is used as the curing radiation, the irradiation dose (cumulative light intensity) is preferably 1000 mJ / cm². 2 ~10000mJ / cm 2 More preferably 2000 mJ / cm 2 ~4000mJ / cm 2 A further preferred value is 3000 mJ / cm². 2 .

[0081] (Energy storage modulus)

[0082] The storage modulus (G'b85) of the adhesive layer A before curing at 85°C is not particularly limited, but is preferably less than 65 kPa, more preferably less than 60 kPa, further preferably less than 55 kPa, particularly preferably less than 50 kPa, and even more preferably less than 45 kPa. This configuration is preferred from the perspective of achieving excellent height difference absorption of the adhesive layer A before curing. Furthermore, G'b85 is not particularly limited, but from the viewpoint of processability and operability, it is preferably 5 kPa or more, more preferably 10 kPa or more, and even more preferably 15 kPa or more. The storage modulus (G'b85) of the adhesive layer A before curing at 85°C can be adjusted, for example, by the composition of the mixed adhesive composition used to form the adhesive layer A (e.g., the molecular weight, amount used, monomer composition, type and amount of functional groups of the base polymer; the type and amount of crosslinking agent (especially the first crosslinking agent); the Mw and Tg of the BP polymer; the weight fraction of the BP polymer; the composition, type and amount of functional groups of the monomer components constituting the BP polymer and the olefin unsaturated compound; the type and amount of crosslinking agent).

[0083] The storage modulus (G'a10) of the cured adhesive layer A at 10°C is not particularly limited, but is preferably 90 kPa or more, more preferably 100 kPa or more, more preferably 110 kPa or more, more preferably 120 kPa or more, more preferably 130 kPa or more, more preferably greater than 146 kPa, more preferably 180 kPa or more, even more preferably 200 kPa or more, particularly preferably 250 kPa or more, and may also be 300 kPa or more, or 350 kPa or more. This configuration is preferred from the viewpoint of achieving excellent processability of the cured adhesive layer A. In addition, G'a10 is not particularly limited, but from the viewpoint of adhesive reliability, it is, for example, 5000 kPa or less, preferably 2500 kPa or less, and more preferably 1000 kPa or less. The storage modulus (G'a10) of the cured adhesive layer A at 10°C can be adjusted, for example, by the composition of the mixed adhesive composition used to form the adhesive layer A (e.g., the molecular weight, amount used, monomer composition, type and amount of functional groups of the base polymer; the type and amount of crosslinking agent (especially the second crosslinking agent); the Mw, Tg, and BP equivalent of the BP polymer (A); the weight fraction of the BP polymer; the composition, type and amount of functional groups of the monomer components constituting the BP polymer and the olefin unsaturated compound; and the type and amount of crosslinking agent).

[0084] The ratio (G'a10 / G'b85) of the storage modulus of the cured adhesive layer A at 10°C to the storage modulus of the uncured adhesive layer A at 85°C is not particularly limited. For example, it is preferably greater than 3.3, more preferably 3.4 or more, further preferably 3.5 or more, particularly preferably 3.6 or more, and may also be 3.7 or more, 3.8 or more, 3.9 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, or 11 or more. This configuration is preferred from the perspective of balancing the excellent height difference absorption of the uncured adhesive layer A and the excellent processability of the cured adhesive layer A. In addition, G'a10 / G'b85 is not particularly limited, but from the viewpoint of processability, operability, and bonding reliability, it is preferably 100 or less, more preferably 50 or less, and further preferably 30 or less. The ratio (G'a10 / G'b85) of the storage modulus of the cured adhesive layer A at 10°C to the storage modulus of the uncured adhesive layer A at 85°C can be adjusted, for example, by the composition of the mixed adhesive composition used to form the adhesive layer A (e.g., the molecular weight, amount used, monomer composition, type and amount of functional groups of the base polymer; the type, amount and ratio of crosslinking agents (especially the first and second crosslinking agents); the Mw, Tg, and BP equivalent of the BP polymer; the weight fraction of the BP polymer; the composition, type and amount of functional groups of the monomer components constituting the BP polymer and the olefin unsaturated compound; and the type and amount of crosslinking agents).

[0085] The storage modulus (G'b10) of the adhesive layer A before curing at 10°C is not particularly limited. From the viewpoint of processability and operability, it is preferably 10 kPa or more, more preferably 50 kPa or more, further preferably 70 kPa or more, or may be 90 kPa or more, or 100 kPa or more. Furthermore, G'b10 is not particularly limited. From the viewpoint of adhesive reliability, it is preferably 5000 kPa or less, preferably 2500 kPa or less, and more preferably 1000 kPa or less. The storage modulus (G'b10) of the adhesive layer A before curing at 10°C can be adjusted, for example, by the composition of the mixed adhesive composition used to form the adhesive layer A (e.g., the molecular weight, amount used, monomer composition, type and amount of functional groups of the base polymer; the type and amount of crosslinking agent (especially the first crosslinking agent); the Mw and Tg of the BP polymer; the weight fraction of the BP polymer; the composition, type and amount of functional groups of the monomer components constituting the BP polymer and the olefin unsaturated compound; and the type and amount of crosslinking agent).

[0086] The storage modulus (G'a85) of the cured adhesive layer A at 85°C is not particularly limited, but from the viewpoint of processability and operability, it is preferably 10 kPa or more, preferably 20 kPa or more, and more preferably 30 kPa or more. Furthermore, G'a85 is not particularly limited, but from the viewpoint of adhesive reliability, it is preferably 1000 kPa or less, preferably 500 kPa or less, and more preferably 200 kPa or less. The storage modulus (G'a85) of the cured adhesive layer A at 85°C can be adjusted, for example, by the composition of the mixed adhesive composition used to form the adhesive layer A (e.g., the molecular weight, amount used, monomer composition, type and amount of functional groups of the base polymer; the type and amount of crosslinking agent (especially the second crosslinking agent); the Mw, Tg, and BP equivalent of the BP polymer; the weight fraction of the BP polymer; the composition, type and amount of functional groups of the monomer components constituting the BP polymer and the olefin unsaturated compound; and the type and amount of crosslinking agent).

[0087] The storage modulus (G'a25) of the cured adhesive layer A at 25°C is not particularly limited, but is preferably 70 kPa or more, more preferably greater than 100 kPa, more preferably 150 kPa or more, and even more preferably 170 kPa or more. This configuration is preferred from the perspective of achieving excellent processability of the cured adhesive layer A. Furthermore, G'a25 is not particularly limited, but from the viewpoint of adhesive reliability, it is, for example, 5000 kPa or less, preferably 2500 kPa or less, and more preferably 1000 kPa or less. The storage modulus (G'a25) of the cured adhesive layer A at 25°C can be adjusted, for example, by the composition of the mixed adhesive composition used to form the adhesive layer A (e.g., the molecular weight, amount used, monomer composition, type and amount of functional groups of the base polymer; the type and amount of crosslinking agent (especially the second crosslinking agent); the Mw, Tg, and BP equivalent of the BP polymer; the weight fraction of the BP polymer; the composition, type and amount of functional groups of the monomer components constituting the BP polymer and the olefin unsaturated compound; and the type and amount of crosslinking agent).

[0088] The storage modulus (G'b25) of the adhesive layer A before curing at 25°C is not particularly limited, but is, for example, 300 kPa or less, preferably 250 kPa or less, and more preferably 200 kPa or less. This configuration is preferred from the perspective of achieving excellent height difference absorption of the adhesive layer A before curing. Furthermore, G'b25 is not particularly limited, but from the viewpoint of adhesive reliability, it is, for example, 10 kPa or more, preferably 30 kPa or more, and more preferably 50 kPa or more. The storage modulus (G'b25) of the adhesive layer A before curing at 25°C can be adjusted, for example, by the composition of the mixed adhesive composition used to form the adhesive layer A (e.g., the molecular weight, amount used, monomer composition, type and amount of functional groups of the base polymer described later; the type and amount of crosslinking agent (especially the first crosslinking agent); the Mw and Tg of the BP polymer; the weight fraction of the BP polymer; the composition, type and amount of functional groups of the monomer components constituting the BP polymer and the olefin unsaturated compound; and the type and amount of crosslinking agent).

[0089] The ratio (G'a25 / G'b85) of the storage modulus of the cured adhesive layer A at 10°C to the storage modulus of the uncured adhesive layer A at 85°C is not particularly limited, but is preferably 0.3 or more, more preferably 0.5 or more, more preferably 1 or more, more preferably greater than 3, preferably 3.5 or more, and more preferably 4 or more. This configuration is preferred from the perspective of balancing the excellent height difference absorption of the uncured adhesive layer A and the excellent processability of the cured adhesive layer A. In addition, G'a25 / G'b85 is not particularly limited, but is preferably 100 or less, preferably 50 or less, and more preferably 30 or less from the viewpoint of processability, operability, and bonding reliability. The ratio (G'a25 / G'b85) of the storage modulus of the cured adhesive layer A at 10°C to the storage modulus of the uncured adhesive layer A at 85°C can be adjusted, for example, by the composition of the mixed adhesive composition used to form the adhesive layer A (e.g., the molecular weight, amount used, monomer composition, type and amount of functional groups of the base polymer; the type, amount and ratio of crosslinking agents (especially the first and second crosslinking agents); the Mw, Tg, and BP equivalent of the BP polymer; the weight fraction of the BP polymer; the composition, type and amount of functional groups of the monomer components constituting the BP polymer and the olefin unsaturated compound; and the type and amount of crosslinking agents).

[0090] The curing conditions for the "cured adhesive layer A" are not particularly limited, but ultraviolet light, which allows the adhesive layer A to transmit light, is preferred. More preferably, ultraviolet light with a wavelength of 200–400 nm is used, and even more preferably, ultraviolet light with a wavelength of 330–400 nm is used. As the light source for ultraviolet irradiation, for example, a high-pressure mercury lamp, a low-pressure mercury lamp, a microwave excitation lamp, a metal halide lamp, a chemical lamp, a black light lamp, or an LED can be used. Furthermore, the irradiation energy, irradiation time, and irradiation method for curing can be appropriately set as long as the adhesive layer A is cured without adversely affecting the adhered material. For example, when ultraviolet light is used as the curing radiation, the irradiation dose (cumulative light intensity) is preferably 1000 mJ / cm². 2 ~10000mJ / cm 2 More preferably 2000 mJ / cm 2 ~4000mJ / cm 2 A further preferred value is 3000 mJ / cm². 2 .

[0091] In addition, the aforementioned energy storage modulus is a value obtained through dynamic viscoelasticity measurement.

[0092] (Other properties of adhesive layer A)

[0093] The gel content of the adhesive layer A before curing is 50-90% by weight, preferably 50-80% by weight, and more preferably 50-70% by weight. By keeping the gel content below 90% by weight, the cohesive force of the adhesive layer A is reduced to a certain extent, and the adhesive layer A becomes softer. Therefore, the adhesive layer becomes easier to follow the height difference portion, and excellent height difference absorption can be obtained. On the other hand, by keeping the gel content above 50% by weight, the problem of the adhesive layer becoming too soft and the reduced processability and operability of the adhesive sheet can be suppressed. In addition, the occurrence of bubbles and floating can be suppressed in high temperature and high temperature and humidity environments, and the bonding reliability can be improved. The gel content can be controlled, for example, by the type and content (amount) of the aforementioned crosslinking agent.

[0094] The gel ratio (the ratio of solvent-insoluble components) mentioned above can be determined in terms of the ethyl acetate-insoluble components. Specifically, it is determined as the weight fraction (in weight %) of the insoluble components after the adhesive layer has been immersed in ethyl acetate at room temperature (23°C) for 7 days relative to the sample before immersion. More specifically, the gel ratio mentioned above refers to the value calculated by the following "Method for Determination of Gel Ratio".

[0095] (Method for determining gelation rate)

[0096] Approximately 1g of the adhesive layer was taken and its weight was measured; this weight was taken as the "weight of the adhesive layer before impregnation". Next, the taken adhesive layer was impregnated in 40g of ethyl acetate for 7 days. All components insoluble in ethyl acetate (the undissolved portion) were recovered. The recovered undissolved portion was dried at 130°C for 2 hours to remove the ethyl acetate, and its weight was measured; this was taken as the "dry weight of the undissolved portion" (the weight of the adhesive layer after impregnation). Then, the obtained value was substituted into the following formula to calculate...

[0097] Gel yield (wt%) = [(dry weight of undissolved portion) / (weight of adhesive layer before impregnation)] × 100

[0098] The gelation rate of the adhesive layer A before curing can be adjusted, for example, by the composition of the mixed adhesive composition used to form the adhesive layer A (e.g., the molecular weight, amount used, monomer composition, type and amount of functional groups of the base polymer described later; the type and amount of crosslinking agent (especially the first crosslinking agent); the Mw and Tg of the BP polymer (A); the weight fraction of the BP polymer; the composition, type and amount of functional groups of the monomer components constituting the BP polymer and the olefin unsaturated compound; the type and amount of crosslinking agent), curing conditions (heating conditions, radiation irradiation conditions), etc.

[0099] Furthermore, the glass transition temperature (Tg) of the adhesive layer A before curing is not particularly limited, but is preferably -60 to 20°C, more preferably -40 to 10°C, and even more preferably -30 to 0°C. When the Tg is higher than 20°C, adhesive strength cannot be exhibited at room temperature.

[0100] The Tg value is not particularly limited. For example, the adhesive layer can be used as the sample for measurement, and the measurement can be performed using differential scanning calorimetry (DSC) according to JIS K 7121. Specifically, for example, a TA Instruments "Q-2000" device can be used as the measuring apparatus, and the measurement can be performed at -80°C to 80°C at a heating rate of 10°C / min.

[0101] The thickness of adhesive layer A is not particularly limited, and can be appropriately set to ensure sufficient sealing of the light-emitting elements arranged on the display panel as described later. For example, the thickness of adhesive layer A can be adjusted to be 1.0 to 4.0 times the height of the light-emitting element, preferably 1.1 to 3.0 times, more preferably 1.2 to 2.5 times, and even more preferably 1.3 to 2.0 times. By setting the thickness to 1.0 times or more, adhesive layer A can easily follow the height difference, thus improving height difference absorption. In addition, by setting the thickness to 4.0 times or less, deformation of adhesive layer A is less likely to occur, thus improving processability.

[0102] The thickness of adhesive layer A is, for example, about 10 to 500 μm, or more than 20 μm, 30 μm, 40 μm, or 50 μm. The thickness of adhesive layer A can also be less than 400 μm, 300 μm, 250 μm, or 200 μm. By making the thickness 10 μm or more, adhesive layer A can easily follow the height difference, improving height difference absorption. Furthermore, by making the thickness less than 500 μm, deformation of adhesive layer A is less likely, improving processability.

[0103] The maximum transmittance of adhesive layer A at wavelengths of 200–400 nm (preferably 330–400 nm) is greater than the maximum transmittance at wavelengths of 400–700 nm.

[0104] Compared to the ultraviolet region (wavelength 200–400 nm, preferably 330–400 nm), adhesive layer A has low transmittance of visible light (wavelength 400–700 nm). Adhesive layer A, with its excellent visible light shielding properties, seals the minute height difference between the metal wiring layer and the light-emitting element (LED chip) of the self-emissive display device (mini / micro LED display device) without gaps, thereby preventing reflections caused by metal wiring, preventing color mixing of the light-emitting element (LED chip), and improving image contrast.

[0105] On the other hand, adhesive layer A has a higher transmittance in the ultraviolet region (wavelength 200-400 nm, preferably 330-400 nm) compared to visible light, and therefore can be cured by irradiation with ultraviolet light. Adhesive layer A cured by ultraviolet irradiation has improved processability and can suppress insufficient adhesive during cutting, overflow of adhesive layer from the end during storage, and sagging.

[0106] In this specification, "maximum transmittance in the wavelength range of 200–400 nm" refers to the highest transmittance within the region of 200–400 nm. For example, when a maximum transmittance exists in the wavelength range of 200–400 nm, that maximum is called the maximum transmittance. Conversely, when no maximum transmittance exists in the wavelength range of 200–400 nm, the higher transmittance between 200 nm and 400 nm is called the maximum. The same applies to "maximum transmittance in the wavelength range of 330–400 nm" and "maximum transmittance in the wavelength range of 400–700 nm".

[0107] The maximum transmittance of adhesive layer A in the wavelength range of 400–700 nm (visible light region) is, for example, less than 80%, but may also be less than 70%, less than 60%, less than 50%, less than 40%, less than 30%, less than 20%, or less than 10%.

[0108] Furthermore, the average transmittance of adhesive layer A at wavelengths of 200–400 nm (preferably 330–400 nm) is greater than that at wavelengths of 400–700 nm. The average transmittance of adhesive layer A at wavelengths of 400–700 nm (visible light region) is, for example, 80% or less, or may be 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less.

[0109] Adhesive layer A exhibits excellent light-shielding properties against visible light, thus preventing reflection and gloss on the metal surface even when a metal substrate is laminated on adhesive layer A. The reflectance of the visible light region with 5° regular reflection when a metal substrate is laminated on adhesive layer A is preferably 50% or less, more preferably 30% or less, further preferably 15% or less, and particularly preferably 10% or less. The gloss (based on JIS Z 8741-1997) when a metal substrate is laminated on adhesive layer A is preferably 100% or less, more preferably 80% or less, further preferably 60% or less, and particularly preferably 50% or less.

[0110] It should be noted that the metals to be bonded include copper, aluminum, and stainless steel.

[0111] (Coloring agent)

[0112] The adhesive layer A contains a colorant. As the aforementioned colorant, it is preferred that the maximum transmittance at wavelengths of 200 to 400 nm (preferably 330 to 400 nm) is greater than the maximum transmittance at wavelengths of 400 to 700 nm (hereinafter sometimes referred to as "colorant (A)").

[0113] The configuration in which the maximum transmittance of the adhesive layer A at wavelengths of 200–400 nm (preferably 330–400 nm) is greater than the maximum transmittance at wavelengths of 400–700 nm is not particularly limited, and can preferably be achieved by including colorant A.

[0114] The maximum transmittance of the aforementioned colorant (including colorant A) in the wavelength range of 400-700 nm (visible light region) is, for example, less than 80%, or less than 70%, less than 60%, less than 50%, less than 40%, less than 30%, less than 20%, less than 10%, or less than 5%.

[0115] Furthermore, the colorant (containing colorant A) preferably has an average transmittance at wavelengths of 200–400 nm (preferably 330–400 nm) greater than its average transmittance at wavelengths of 400–700 nm. The average transmittance of the aforementioned colorant (containing colorant A) at wavelengths of 400–700 nm (visible light region) is, for example, 80% or less, or may be 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less.

[0116] Regarding the transmittance of the colorant (including colorant A), it can be measured using a solution or dispersion prepared by dilution with a suitable solvent such as tetrahydrofuran (THF) or a dispersion medium (an organic solvent with low absorption in the wavelength range of 200-700 nm) with a transmittance of about 50-60% at a wavelength of 400 nm.

[0117] The colorant (including colorant A) can be either a dye or a pigment, as long as it can be dissolved or dispersed in the binder layer A. Dyes are preferred from the perspective of achieving low haze even with small amounts, non-settling like pigments, and easy uniform distribution. Pigments are also preferred from the perspective of high color development even with small amounts. When using a pigment as a colorant, it is preferable to have low or no conductivity. Furthermore, when using a dye, it is preferable to use it in combination with antioxidants, etc.

[0118] Examples of black pigments that transmit ultraviolet light include TOKUSHIKI's "9050BLACK", "9256BLACK", "9170BLACK", and "UVBK-0001", and Mitsubishi Materials Electronic Chemicals Co., Ltd.'s "UB-1". Examples of black dyes that transmit ultraviolet light include Orient Chemical Industries Co., Ltd.'s "SOC-L-0123".

[0119] The content of colorant (including colorant A) in adhesive layer A is, for example, about 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight, relative to 100 parts by weight of adhesive layer A, and can be appropriately set according to the type of colorant, the hue of adhesive layer A, and light transmittance. The colorant can also be added in the form of a solution or dispersion prepared by dissolving or dispersing in a suitable solvent.

[0120] (Mixed adhesive composition)

[0121] The adhesive composition used to form adhesive layer A is not particularly limited as long as it meets the above characteristics (a) to (d), and is preferably a mixed adhesive composition containing a colorant (preferably colorant A).

[0122] The hybrid adhesive is an adhesive that is cured in stages by mixing two polymerization initiators, crosslinking agents or crosslinking functional groups (in this specification, the polymerization initiator, crosslinking agent or crosslinking functional group is sometimes referred to as "trigger") with different curing initiation conditions such as heat or light.

[0123] In the mixed adhesive, firstly, a semi-cured state with high fluidity and excellent height difference absorption is prepared by one of the initiators (sometimes referred to as "first initiator" in this specification), so as to fully follow the height difference. Then, light is irradiated, and curing is completed by the other initiator (sometimes referred to as "second initiator" in this specification), which can improve processability.

[0124] The mixed adhesive composition constituting adhesive layer A is not particularly limited, but typically contains a base polymer, a crosslinking agent, and a photopolymerization initiator. Here, the base polymer is a polymer that is cured by the aforementioned first initiator, and the crosslinking agent and photopolymerization initiator are equivalent to the second initiator.

[0125] There are no particular limitations on the aforementioned base polymers, as long as they are materials with adhesive properties suitable for optical applications. For example, suitable polymers can be selected and used from the following: acrylic polymers contained in acrylic adhesive layers, rubber polymers contained in rubber adhesive layers (natural rubber adhesive layers, synthetic rubber adhesive layers, etc.), silicone polymers contained in silicone adhesive layers, polyester polymers contained in polyester adhesive layers, urethane polymers contained in urethane adhesive layers, polyamide polymers contained in polyamide adhesive layers, epoxy polymers contained in epoxy adhesive layers, vinyl alkyl ether polymers contained in vinyl alkyl ether adhesive layers, and fluorinated polymers contained in fluorinated adhesive layers. Any of these polymers can be used alone or in combination of two or more. From the viewpoint of processability and durability, acrylic polymers are preferred. The aforementioned acrylic polymers are not particularly limited, but homopolymers or copolymers of monomers with (meth)acrylate as the main component are preferred. Here, the term "(meth)acrylic acid" is used to mean either or both of "acrylic acid" and "methacrylic acid," and the same applies elsewhere. In this invention, the term "acrylic polymer" is used to mean, in addition to the aforementioned alkyl methacrylates, other monomers that can be copolymerized with them.

[0126] The aforementioned acrylic polymer preferably comprises monomer units derived from alkyl acrylates having linear or branched alkyl groups, and / or alkyl methacrylates having linear or branched alkyl groups as the most abundant major monomer units by weight.

[0127] Alkyl methacrylates having straight-chain or branched alkyl groups as monomer units used to form the aforementioned acrylic polymers, i.e., alkyl methacrylates containing straight-chain or branched alkyl groups in the monomer components used to form the aforementioned acrylic polymers, include, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, sec-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, amyl methacrylate, isoamyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, and so on. Alkyl methacrylates, such as 2-ethylhexyl acrylate, isooctyl methacrylate, nonyl methacrylate, isononyl methacrylate, decyl methacrylate, isodecanyl methacrylate, undecyl methacrylate, dodecyl methacrylate, tridecyl methacrylate, tetradecyl methacrylate, pentadecyl methacrylate, hexadecyl methacrylate, heptadecanyl methacrylate, octadecyl methacrylate, isostearyl methacrylate, nonadecanyl methacrylate, and eicosyl methacrylate, are linear or branched alkyl groups having 1 to 20 carbon atoms. As the alkyl methacrylate for acrylic polymers, one or more alkyl methacrylates can be used. In this embodiment, as the alkyl methacrylate for acrylic polymers, at least one selected from the group consisting of n-butyl acrylate, 2-ethylhexyl acrylate, and isostearyl methacrylate is preferably used.

[0128] In the aforementioned acrylic polymer, the proportion of monomer units derived from (meth)acrylate alkyl esters having linear or branched alkyl groups is preferably 50% by weight or more, more preferably 60% by weight or more, more preferably 70% by weight or more, more preferably 80% by weight or more, and more preferably 90% by weight or more. That is, the proportion of (meth)acrylate alkyl esters in the monomer composition of the raw materials used to form the acrylic polymer is preferably 50% by weight or more, more preferably 60% by weight or more, more preferably 70% by weight or more, more preferably 80% by weight or more, and more preferably 90% by weight or more.

[0129] The aforementioned acrylic polymers may contain monomer units derived from alicyclic monomers. Alicyclic monomers used as monomer units to form acrylic polymers, i.e., alicyclic monomers contained in the monomer components used to form the acrylic polymer, include, for example, cycloalkyl methacrylates, (meth)acrylates having a bicyclic hydrocarbon ring, and (meth)acrylates having three or more hydrocarbon rings. Examples of cycloalkyl methacrylates include, for example, cyclopentyl methacrylate, cyclohexyl methacrylate, cycloheptyl methacrylate, and cyclooctyl methacrylate. Examples of (meth)acrylates having a bicyclic hydrocarbon ring include, for example, borneol methacrylate and isoborneol methacrylate. Examples of (meth)acrylates having three or more hydrocarbon rings include dicyclopentyl (meth)acrylate, dicyclopentyloxyethyl (meth)acrylate, tricyclopentyl (meth)acrylate, 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, and 2-ethyl-2-adamantyl (meth)acrylate. As an alicyclic monomer for acrylic polymers, one or more alicyclic monomers may be used. In this embodiment, at least one alicyclic monomer selected from the group consisting of cyclohexyl acrylate, cyclohexyl methacrylate, isobornyl acrylate, and isobornyl methacrylate is preferably used as the alicyclic monomer for acrylic polymers.

[0130] From the viewpoint of achieving adequate flexibility in the base polymer formed by including the acrylic polymer, the ratio of monomer units derived from alicyclic monomers in the aforementioned acrylic polymer is preferably 5 to 60% by weight, more preferably 10 to 50% by weight, and even more preferably 12 to 40% by weight. Furthermore, in some embodiments of the present invention, the aforementioned acrylic polymer may also be free of monomer units derived from alicyclic monomers.

[0131] The aforementioned acrylic polymers may contain monomer units derived from hydroxyl-containing monomers. A hydroxyl-containing monomer is a monomer having at least one hydroxyl group within its monomer unit. When the acrylic polymer within the base polymer contains hydroxyl-containing monomer units, adhesiveness and moderate cohesion are readily obtained in the base polymer. Furthermore, the hydroxyl group can also serve as a reaction site with the crosslinking agent described later.

[0132] Hydroxyl-containing monomers used as monomer units to form the aforementioned acrylic polymers, i.e., hydroxyl-containing monomers contained in the monomer components used to form the acrylic polymers, include, for example, hydroxyl-containing (meth)acrylates, vinyl alcohols, and allyl alcohols. Examples of hydroxyl-containing (meth)acrylates include, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, hydroxyoctyl (meth)acrylate, hydroxydecyl (meth)acrylate, hydroxylauryl (meth)acrylate, and methyl (4-hydroxymethylcyclohexyl)methacrylate. One or more hydroxyl-containing monomers can be used as the hydroxyl-containing monomers used in the acrylic polymers. In this embodiment, as the hydroxyl-containing monomer used for the acrylic polymer, at least one selected from the group consisting of 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, and 4-hydroxybutyl methacrylate is preferably used.

[0133] The proportion of monomer units derived from hydroxyl-containing monomers in the aforementioned acrylic polymer is preferably 1% by weight or more, more preferably 2% by weight or more, more preferably 3% by weight or more, more preferably 7% by weight or more, more preferably 10% by weight or more, and more preferably 15% by weight or more. The proportion of monomer units derived from hydroxyl-containing monomers in the aforementioned acrylic polymer is preferably 35% by weight or less, more preferably 30% by weight or less. These configurations related to the proportion of hydroxyl-containing monomers are suitable for achieving adhesiveness and moderate cohesive strength in the base polymer formed comprising this acrylic polymer.

[0134] The aforementioned acrylic polymers may contain monomer units derived from nitrogen-containing monomers. A nitrogen-containing monomer is a monomer having at least one nitrogen atom within its monomer unit. When the acrylic polymer within the base polymer contains nitrogen-containing monomer units, it is easier to obtain hardness and good adhesive reliability in the base polymer.

[0135] Nitrogen-containing monomers used as monomer units to form the aforementioned acrylic polymers, i.e., nitrogen-containing monomers contained in the monomer components used to form the acrylic polymers, include, for example, N-vinyl cyclic amides and (meth)acrylamides.

[0136] For N-vinyl cyclic amides that are nitrogen-containing monomers, N-vinyl cyclic amides of general formula (1) can be used, for example.

[0137]

[0138] Here, in general formula (1), R1 It is a divalent organic group, specifically -(CH2). n - n is an integer from 2 to 7 (preferably 2, 3 or 4).

[0139] Examples of the aforementioned N-vinyl cyclic amides include N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, and N-vinyl-3,5-morpholindione.

[0140] Examples of nitrogen-containing monomers (meth)acrylamides include (meth)acrylamide, N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-n-butyl(meth)acrylamide, N-octyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, and N,N-diisopropyl(meth)acrylamide. As a nitrogen-containing monomer for acrylic polymers, one nitrogen-containing monomer or two or more nitrogen-containing monomers can be used. In this embodiment, N-vinyl-2-pyrrolidone is preferably used as the nitrogen-containing monomer for acrylic polymers.

[0141] From the viewpoint of achieving appropriate hardness and adhesion in the base polymer formed by including this acrylic polymer, the ratio of monomer units derived from nitrogen-containing monomers in the aforementioned acrylic polymer is preferably 1% by weight or more, more preferably 3% by weight or more, and even more preferably 5% by weight or more. Furthermore, from the viewpoint of preventing excessive hardening and achieving good adhesive reliability in the base polymer formed by including this acrylic polymer, the ratio of monomer units derived from nitrogen-containing monomers in the aforementioned acrylic polymer is preferably 30% by weight or less, more preferably 25% by weight or less. Additionally, in some embodiments of the present invention, the aforementioned acrylic polymer may not contain monomer units derived from nitrogen-containing monomers.

[0142] The aforementioned acrylic polymers may contain monomer units derived from carboxyl-containing monomers. A carboxyl-containing monomer is a monomer having at least one carboxyl group within its monomer unit. When the acrylic polymer within the base polymer contains carboxyl-containing monomer units, good adhesive reliability can sometimes be obtained in the base polymer. Furthermore, the carboxyl group can also serve as a reaction site with the crosslinking agent described later.

[0143] Carboxyl-containing monomers used to form the aforementioned acrylic polymers, i.e., carboxyl-containing monomers contained in the monomer components used to form the acrylic polymers, include, for example, (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid. One or more carboxyl-containing monomers can be used as the carboxyl-containing monomer for the acrylic polymers. In this embodiment, acrylic acid is preferably used as the carboxyl-containing monomer for the acrylic polymers.

[0144] From the viewpoint of ensuring good adhesive reliability by maximizing the contribution of the interaction between the polar groups and carboxyl groups when polar groups are present on the surface of the adherend in the base polymer containing the acrylic polymer, the proportion of monomer units derived from carboxyl-containing monomers in the aforementioned acrylic polymer is preferably 0.1% by weight or more, more preferably 0.5% by weight or more. Furthermore, from the viewpoint of preventing excessive hardening in the base polymer containing the acrylic polymer and achieving good adhesive reliability, the proportion of monomer units derived from carboxyl-containing monomers in the aforementioned acrylic polymer is preferably 20% by weight or less, more preferably 15% by weight or less. Additionally, from the viewpoint of preventing metal corrosion, the aforementioned acrylic polymer may substantially be free of carboxyl-containing monomers as its constituent monomer units. "Substantially free of carboxyl-containing monomers" means that carboxyl-containing monomers are intentionally not used, preferably at 0.05% by weight or less (e.g., 0 to 0.05% by weight), more preferably at 0.01% by weight or less (e.g., 0 to 0.01% by weight), and even more preferably at 0.001% by weight or less (e.g., 0 to 0.001% by weight), which can be said to be substantially free of them.

[0145] The aforementioned acrylic polymer can be a partial polymer of a mixture of monomeric components constituting the acrylic polymer. Alternatively, the aforementioned acrylic polymer can also be a substance formed by adding the remaining monomeric components to a partial polymer of a mixture of monomeric components constituting the acrylic polymer. The aforementioned "partial polymer of a mixture of monomeric components" refers to a composition formed by partially polymerizing one or more of the monomeric components.

[0146] The aforementioned base polymer may contain a crosslinking agent. This crosslinking agent gives the base polymer a crosslinked structure, thereby increasing viscosity, improving shape stability, and facilitating the formation of adhesive layer A. Examples of crosslinking agents include polyfunctional (meth)acrylates and thermosetting crosslinking agents, which are copolymeric crosslinking agents (photocurable crosslinking agents) for acrylic polymers. The aforementioned base polymer may have a crosslinking structure derived solely from polyfunctional (meth)acrylates, a crosslinking structure derived solely from thermosetting crosslinking agents, or a crosslinking structure derived from both polyfunctional (meth)acrylates and thermosetting crosslinking agents.

[0147] It should be noted that the crosslinking agent is the crosslinking agent constituting the first initiator (first crosslinking agent) in the case where the adhesive layer A of the present invention is composed of a mixed adhesive composition. That is, the base polymer having a crosslinking structure derived from the first crosslinking agent is in a highly fluid semi-cured state, exhibiting excellent height difference absorption.

[0148] Examples of polyfunctional (meth)acrylates used as copolymerizing crosslinking agents (photocurable crosslinking agents) include 1,6-hexanediol dimethacrylate, butanediol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, neopentyl glycol dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, dipentaerythritol hexamethacrylate, trimethylolpropane trimethacrylate, tetramethylolmethane trimethacrylate, allyl methacrylate, and vinyl methacrylate. As polyfunctional (meth)acrylates for use in acrylic polymers, one or more polyfunctional (meth)acrylates may be used. In this embodiment, as a multifunctional (meth)acrylate for acrylic polymers, at least one selected from the group consisting of 1,6-hexanediol diacrylate, dipentaerythritol hexaacrylate, trimethylolpropane triacrylate, and polypropylene glycol diacrylate is preferably used.

[0149] The proportion of monomer units derived from polyfunctional (meth)acrylates in the aforementioned acrylic polymer is preferably 0.005% by weight or more, more preferably 0.01% by weight or more, more preferably 0.03% by weight or more, and even more preferably 0.05% by weight or more. The proportion of monomer units derived from polyfunctional (meth)acrylates in the aforementioned acrylic polymer is preferably 1% by weight or less, more preferably 0.5% by weight or less. These configurations related to the proportion of polyfunctional (meth)acrylates are suitable for achieving moderate hardness, adhesion, shape stability, and excellent height difference absorption in the base polymer formed comprising this acrylic polymer.

[0150] Examples of thermosetting crosslinking agents include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, metal chelate-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal salt-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, and amine-based crosslinking agents. The base polymer may contain one or more of these thermosetting crosslinking agents. Preferably, at least one selected from the group consisting of isocyanate-based crosslinking agents and epoxy-based crosslinking agents is used.

[0151] Examples of isocyanate-based crosslinking agents include, for example, lower aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates. Examples of lower aliphatic polyisocyanates include 1,2-ethylene diisocyanate, 1,4-butylene diisocyanate, and 1,6-hexamethylene diisocyanate. Examples of alicyclic polyisocyanates include cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate, hydrogenated toluene diisocyanate, and hydrogenated xylene diisocyanate. Examples of aromatic polyisocyanates include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, and phenylenediamine diisocyanate. In addition, as isocyanate-based crosslinking agents, commercially available products include trimethylolpropane / toluene diisocyanate adduct (trade name "CORONATE L", manufactured by Nippon Polyurethanes Co., Ltd.), trimethylolpropane / hexamethylene diisocyanate adduct (trade name "CORONATE HL", manufactured by Nippon Polyurethanes Co., Ltd.), and trimethylolpropane / phenylenediamine diisocyanate adduct (trade name "TAKENATE D-110N", manufactured by Mitsui Chemicals Co., Ltd.).

[0152] Examples of epoxy crosslinking agents (multifunctional epoxy compounds) include N,N,N',N'-tetraglycidyl-m-phenylenediamine, diglycidyl aniline, 1,3-bis(N,N-diglycidylaminomethyl)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 anhydride polyglycidyl ether, trimethylolpropane polyglycidyl ether, diglycidyl adipate, diglycidyl phthalate, triglycidyl-tris(2-hydroxyethyl)isocyanurate, resorcinol diglycidyl ether, and bisphenol-S-diglycidyl ether. In addition, epoxy resins having two or more epoxy groups can also be listed as epoxy crosslinking agents. Furthermore, commercially available products such as "TETRAD C" (manufactured by Mitsubishi Gas Chemical Co., Ltd.) can also be listed as epoxy crosslinking agents.

[0153] When the thermosetting crosslinking agent described above is included for crosslinking between the base polymers, from the viewpoints of improved shape stability of the base polymer, easy formation of adhesive layer A, sufficient adhesion reliability to the adhered objects, and excellent height difference absorption, the content of the thermosetting crosslinking agent in the base polymer is preferably 0.001 parts by weight or more, more preferably 0.01 parts by weight or more, relative to 100 parts by weight of the total monomer components constituting the base polymer. Furthermore, from the viewpoints of exhibiting moderate softness in the base polymer, achieving good adhesion, and excellent height difference absorption, the content of the thermosetting crosslinking agent is preferably 10 parts by weight or less, more preferably 5 parts by weight or less, relative to 100 parts by weight of the total monomer components constituting the base polymer.

[0154] When the aforementioned base polymer contains the acrylic polymer as a binder as described above, the content of the acrylic polymer in the base polymer is, for example, 85 to 100% by weight.

[0155] In addition to monomers and crosslinking agents for forming acrylic polymers, the aforementioned basic polymer may also contain a polymerization initiator. Examples of polymerization initiators include photopolymerization initiators and thermal polymerization initiators. The aforementioned basic polymer may contain one or more polymerization initiators.

[0156] It should be noted that the polymerization initiator is the polymerization initiator constituting the first initiator (first polymerization initiator) when the adhesive layer A of the present invention is formed from the mixed adhesive composition.

[0157] Examples of photopolymerization initiators include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-keto alcohol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzoyl-based photopolymerization initiators, ketal-based photopolymerization initiators, and thioxanthone-based photopolymerization initiators. Examples of benzoin ether-based photopolymerization initiators include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and 2,2-dimethoxy-1,2-diphenylethane-1-one. Examples of acetophenone-based photopolymerization initiators include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, 4-phenoxydichloroacetophenone, and 4-(tert-butyl)dichloroacetophenone. Examples of α-keto-alcohol-based photopolymerization initiators include 2-methyl-2-hydroxyphenylacetone and 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropane-1-one. Examples of aromatic sulfonyl chloride-based photopolymerization initiators include 2-naphthalenesulfonyl chloride. Examples of photoactive oxime-based photopolymerization initiators include 1-phenyl-1,1-propanedione-2-(O-ethoxycarbonyl)-oxime. Examples of benzoin-based photopolymerization initiators include benzoin. Examples of benzoinyl-based photopolymerization initiators include benzoinyl. Examples of benzophenone-based photopolymerization initiators include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, and polyvinylbenzophenone. Examples of ketal-based photopolymerization initiators include benzoyldimethyl ketal. Examples of thioxanthone-based photopolymerization initiators include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone.

[0158] The amount of the above-mentioned photopolymerization initiator is not particularly limited. For example, it is preferably 0.001 to 1 part by weight, more preferably 0.01 to 0.50 parts by weight, relative to 100 parts by weight of all monomer units of the acrylic polymer (the total amount of monomer components constituting the acrylic polymer).

[0159] Examples of thermal polymerization initiators include azo-based polymerization initiators, peroxide-based polymerization initiators, and redox-based polymerization initiators. Examples of azo-based polymerization initiators include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis-2-methylbutyronitrile (AMBN), dimethyl 2,2'-azobis(2-methylpropionic acid) ester, 4,4'-azobis-4-cyanopentanoic acid, 2,2'-azobis(4-methoxy-2,4-dimethylpentanonitrile), 2,2'-azobis(2,4-dimethylpentanonitrile), 1,1'-azobis(cyclohexane-1-carboxylonitrile), and 2,2'-azobis(2,4,4-trimethylpentane). Examples of peroxide-based polymerization initiators include benzoyl peroxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, tert-butyl peroxide, diisopropylbenzene peroxide, 1,1-bis(tert-butyl peroxide)-3,3,5-trimethylcyclohexane, and 1,1-bis(tert-butyl peroxide)cyclododecane.

[0160] The amount of the above-mentioned thermal polymerization initiator is not particularly limited. For example, it is preferably 0.05 to 0.5 parts by weight, more preferably 0.1 to 0.3 parts by weight, relative to 100 parts by weight of all monomer units of the acrylic polymer (the total amount of monomer components constituting the acrylic polymer).

[0161] As a crosslinking agent included in the mixed adhesive composition constituting adhesive layer A, polyfunctional (meth)acrylates, such as the aforementioned copolymeric crosslinking agent (photocurable crosslinking agent), can be cited as examples. It should be noted that this crosslinking agent is the crosslinking agent constituting the second initiator (second crosslinking agent) in the case where adhesive layer A of the present invention is composed of a mixed adhesive composition. That is, the base polymer cured by this second crosslinking agent achieves excellent processability.

[0162] The content of the polyfunctional (meth)acrylate as the second crosslinking agent is not particularly limited. From the viewpoint of imparting excellent processability to the cured base polymer, it is preferably 0.1 parts by weight or more, more preferably 1 part by weight or more, more preferably 2 parts by weight or more, and more preferably 4 parts by weight or more, relative to 100 parts by weight of the base polymer. Furthermore, the aforementioned content of the polyfunctional (meth)acrylate is preferably 60 parts by weight or less, more preferably 40 parts by weight or less, relative to 100 parts by weight of the base polymer. These configurations, related to the content of the polyfunctional (meth)acrylate as the second crosslinking agent, are suitable for achieving excellent processability by curing the base polymer containing this acrylic polymer.

[0163] The photopolymerization initiator included in the mixed adhesive composition constituting adhesive layer A can be any substance similar to the aforementioned photopolymerization initiator. It should be noted that this photopolymerization initiator is the polymerization initiator constituting the second initiator (second polymerization initiator) in the case where adhesive layer A of the present invention is composed of a mixed adhesive composition. That is, the base polymer cured by the photopolymerization initiator, which is this second polymerization initiator, achieves excellent processability.

[0164] The content of the photopolymerization initiator, which serves as the second polymerization initiator, is not particularly limited. From the viewpoint of imparting excellent processability to the cured base polymer, it is preferably 0 to 2 parts by weight, and more preferably 0.005 to 1.5 parts by weight, relative to 100 parts by weight of the base polymer. These configurations, related to the content of the photopolymerization initiator as the second polymerization initiator, are suitable for achieving excellent processability by curing the base polymer containing this acrylic polymer.

[0165] The mixed adhesive composition constituting adhesive layer A may further include, as needed, additives such as ultraviolet absorbers, rust inhibitors, antistatic agents, crosslinking accelerators, silane coupling agents, tackifying resins, anti-aging agents, fillers, antioxidants, chain transfer agents, plasticizers, softeners, surfactants, polyols, and solvents. Examples of tackifying resins include rosin derivatives, polyterpene resins, petroleum resins, and oil-soluble phenols.

[0166] The mixed adhesive composition constituting adhesive layer A may contain a silane coupling agent, to a extent that does not impair the effects of the present invention. The inclusion of a silane coupling agent in adhesive layer A improves the bonding reliability to glass (especially the bonding reliability to glass under high temperature and high humidity conditions), which is preferred.

[0167] The aforementioned silane coupling agent is not particularly limited, but preferably includes γ-epoxypropoxypropyltrimethoxysilane, γ-epoxypropoxypropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and N-phenyl-aminopropyltrimethoxysilane. Among these, γ-epoxypropoxypropyltrimethoxysilane is preferred. Furthermore, commercially available products, such as "KBM-403" (manufactured by Shin-Etsu Chemical Co., Ltd.), are examples. It should be noted that two or more silane coupling agents can be used alone or in combination.

[0168] The content of silane coupling agent in the mixed adhesive composition constituting adhesive layer A is not particularly limited, but is preferably 0.01 to 1 part by weight, more preferably 0.03 to 0.5 parts by weight, relative to 100 parts by weight of the base polymer.

[0169] The mixed adhesive composition constituting adhesive layer A may contain polyols, to a extent that does not impair the effects of the present invention. When adhesive layer A contains polyols, for example, a cross-linked structure based on the first cross-linking agent (particularly the aforementioned thermosetting cross-linking agent) is formed, which improves the high-gradient absorption and is preferred.

[0170] The aforementioned polyols are not specifically limited and can include polyester polyols, polycarbonate polyols, polyacrylic acid polyols, polyether polyols, epoxy polyols, polyolefin polyols, and polyether ester polyols. Additionally, a commercially available product, for example, is "Adeka polyether EPD-300" (manufactured by ADEKA Co., Ltd.). It should be noted that polyols can be used alone or in combination of two or more.

[0171] The content of polyol in the mixed adhesive composition constituting adhesive layer A is not particularly limited, but is preferably 0.01 to 1 part by weight, more preferably 0.03 to 0.5 parts by weight, relative to 100 parts by weight of the base polymer.

[0172] In addition, the mixed adhesive composition constituting adhesive layer A may contain a solvent. There are no particular limitations on the solvent, but examples 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; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; and ketones such as methyl ethyl ketone and methyl isobutyl ketone. It should be noted that two or more solvents may be used alone or in combination.

[0173] The method for forming the aforementioned adhesive layer A is not particularly limited. As a first embodiment, examples include: applying the aforementioned mixed adhesive composition onto a support and drying and curing the resulting adhesive layer; applying the aforementioned mixed adhesive onto a support and irradiating the resulting adhesive layer with active energy rays to cure it. If necessary, further heating and drying may also be performed.

[0174] It should be noted that the aforementioned drying and curing, active energy ray irradiation, and heating drying require selecting conditions that allow only the curing of the crosslinking agent and polymerization initiator constituting the first initiator to proceed, while the curing reaction of the crosslinking agent and photopolymerization initiator constituting the second initiator does not proceed or is inhibited.

[0175] There are no particular limitations on the aforementioned support, but a plastic film is preferred. Examples of raw materials for the aforementioned plastic film include polyester resins such as polyethylene terephthalate (PET), acrylic resins such as polymethyl methacrylate (PMMA), polycarbonate, triacetyl cellulose (TAC), polysulfone, polyarylate, polyimide, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, ethylene-propylene copolymer, and cyclic olefin polymers such as "Arton" (a cyclic olefin polymer manufactured by JSR Corporation) and "ZEONOR" (a cyclic olefin polymer manufactured by Zeon Corporation). It should be noted that only one of these plastic materials may be used, or two or more may be used.

[0176] The aforementioned support can also be a release sheet. There are no particular limitations on the release sheet; examples include plastic films that have undergone surface treatment with release agents such as silicone-based, long-chain alkyl-based, fluorine-based, and molybdenum sulfide.

[0177] The coating (coating) of the aforementioned mixed adhesive composition can be performed using known coating methods, such as gravure roller coating machines, reverse roller coating machines, licking roller coating machines, dip roller coating machines, bar coating machines, doctor blade coating machines, spray coating machines, comma coating machines, direct coating machines, and other coating machines.

[0178] The drying and curing temperature is preferably 40–200°C, more preferably 50–180°C, and even more preferably 60–170°C. The drying and curing time can be an appropriate and suitable time, for example, 5 seconds to 20 minutes, preferably 5 seconds to 10 minutes, and more preferably 10 seconds to 5 minutes.

[0179] Examples of active energy rays include ionizing radiation such as alpha rays, beta rays, gamma rays, neutron rays, and electron rays, as well as ultraviolet radiation. Ultraviolet radiation, which allows the adhesive layer A to transmit light, is particularly preferred. That is, adhesive layer A has high light-blocking properties to visible light and high transmittance to ultraviolet light, thus enabling the base polymer to be cured by ultraviolet light. Furthermore, the irradiation energy, irradiation time, and irradiation method of the active energy rays are not particularly limited; they can be appropriately set according to the thickness of adhesive layer A to achieve the desired viscosity and viscoelasticity.

[0180] When the adhesive layer formed above is not facing the main surface of the support, and is photocured using the above-mentioned active energy rays and / or ultraviolet irradiation as described later, it is preferable to further laminate it with other supports (including release sheets) in order to block oxygen that would inhibit photocuring.

[0181] In addition, as another preferred second embodiment of the aforementioned method for forming adhesive layer A, a method comprising the following steps can be listed.

[0182] (1) An adhesive layer is formed from a single layer of the aforementioned base polymer.

[0183] (2) Curing the aforementioned adhesive layer.

[0184] (3) Prepare a solution of the aforementioned crosslinking agent and / or the aforementioned photopolymerization initiator.

[0185] (4) Apply the aforementioned solution to one side of the aforementioned cured adhesive layer, so that the aforementioned crosslinking agent and / or the aforementioned photopolymerization initiator contained in the solution penetrate from the aforementioned one side of the aforementioned adhesive layer along the thickness direction.

[0186] (5) Dry the aforementioned adhesive layer.

[0187] By forming adhesive layer A using the second embodiment described above, the curing reaction based on the crosslinking agent and polymerization initiator constituting the first initiator can be separated from the curing reaction based on the crosslinking agent and photopolymerization initiator constituting the second initiator. Therefore, it is no longer necessary to select curing reaction conditions that only involve curing based on the crosslinking agent and polymerization initiator constituting the first initiator, and the degree of freedom in the combination of the crosslinking agent and polymerization initiator constituting the first initiator and the crosslinking agent and polymerization initiator constituting the second initiator is significantly improved.

[0188] Furthermore, by separating the curing reaction based on the crosslinking agent and polymerization initiator constituting the first initiator from the curing reaction based on the crosslinking agent and photopolymerization initiator constituting the second initiator, it becomes easier to adjust the height difference absorption of the base polymer obtained by curing the first initiator and the processability of the base polymer cured by the second initiator. The ease and freedom of designing a photocurable adhesive sheet A with an adhesive layer A that balances superior height difference absorption and processability are also significantly improved.

[0189] Figure 2 A cross-sectional view illustrating the process of the second embodiment of the method for manufacturing a photocurable adhesive sheet A.

[0190] Figure 2 In (a), firstly, an adhesive layer 10a formed of a base polymer is formed on the support S1.

[0191] In the aforementioned adhesive layer formation process, firstly, the base polymer, which is not mixed with the crosslinking agent and photopolymerization initiator constituting the second initiator, is coated onto the support S1. The same support as in the first embodiment can be used as the support.

[0192] The coating (coating) of the aforementioned basic polymer can be performed using known coating methods, such as gravure roller coating machines, reverse roller coating machines, licking roller coating machines, dip roller coating machines, bar coating machines, doctor blade coating machines, spray coating machines, comma coating machines, direct coating machines, and other coating machines.

[0193] For the main surface of the adhesive layer 10a not facing the support S1, in the case of photocuring the adhesive layer by means of active energy rays and / or ultraviolet irradiation as described later in the adhesive layer curing process, in order to block the oxygen that would inhibit photocuring, it is preferable to further laminate it with other supports S2 (including release sheets).

[0194] Next, the adhesive layer 10a is cured (adhesive layer curing process). Figure 2 In (b), 10b is the adhesive layer formed by curing the adhesive layer 10a. The method for curing the adhesive layer 10a is not particularly limited; examples include heating the adhesive layer 10a; and irradiating the adhesive layer 10a with active energy rays to cure it. Further heating and drying may be performed as needed. The specific curing conditions are the same as in the first embodiment described above.

[0195] It should be noted that, regarding the aforementioned adhesive layer curing process, the drying and curing, the irradiation with active energy rays, and the heating and drying, since they do not contain the crosslinking agent or photopolymerization initiator constituting the second initiator, any conditions can be used as long as curing based on the crosslinking agent or polymerization initiator constituting the first initiator is performed, which is a very high degree of freedom compared to the first embodiment.

[0196] The conditions for curing the adhesive layer 10a can be appropriately selected according to the embodiment in a way that the adhesive layer 10b has the desired physical properties. For example, the heating temperature, time, or irradiation amount of active energy rays can be appropriately set in a way that the adhesive layer 10b exhibits high fluidity and excellent height difference absorption.

[0197] Figure 2 (b) is an embodiment in which the aforementioned adhesive layer 10a is cured by irradiating it with ultraviolet light U. The adhesive layer 10a constituting the adhesive layer A has high light-shielding properties to visible light and high transmittance to ultraviolet light, and therefore can be cured by ultraviolet light U.

[0198] Ultraviolet light U can be directly irradiated onto the adhesive layer 10a, but in order to block the oxygen that would inhibit curing based on ultraviolet light irradiation, it is preferable to irradiate through a support. Figure 2(b) illustrates an embodiment in which ultraviolet light is irradiated onto the adhesive layer 10a through the support S2. When irradiating with ultraviolet light through the support, another support S2 (including a release liner) is attached to the main surface of the adhesive layer 10a opposite to the main surface facing the support S1, and ultraviolet light is irradiated through this support. The illuminance and duration of ultraviolet irradiation are appropriately set according to the composition of the base polymer, the thickness of the adhesive layer, etc. Ultraviolet irradiation can be performed using high-pressure mercury lamps, low-pressure mercury lamps, microwave excitation lamps, metal halide lamps, chemical lamps, black light lamps, LEDs, etc.

[0199] Next, as Figure 2 As shown in (c), after the support S2 is peeled off, a solution 14 of crosslinking agent 11 and / or photopolymerization initiator 12 is applied to one side of the adhesive layer 10b (solution coating step). Here, crosslinking agent 11 and photopolymerization initiator 12 are the crosslinking agent and photopolymerization initiator constituting the second initiator.

[0200] Solution 14 may contain a solvent, while crosslinking agent 11 may function as a solvent or may not contain a solvent. Figure 2 (c) is an embodiment in which solution 14 is a solution formed by dissolving crosslinking agent 11 and / or photopolymerization initiator 12 in solvent 13.

[0201] As for solvent 13, there are no particular limitations as long as it can dissolve the aforementioned crosslinking agent 11 and / or photopolymerization initiator 12 and can cause the adhesive layer 10b to swell. However, aqueous solvents have poor wettability on the adhesive layer and the additives are difficult to penetrate, so non-aqueous solvents are preferred. As a non-aqueous solvent, there are no particular limitations. Examples include: esters such as methyl acetate, ethyl acetate, isopropyl acetate, and butyl acetate; aromatic hydrocarbons such as toluene, xylene, and ethylbenzene; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; alicyclic ketones such as cyclopentanone and cyclohexanone; alicyclic hydrocarbons such as hexane, heptane, and octane; alicyclic hydrocarbons such as cyclohexane; halogenated hydrocarbons such as chloroform, dichloromethane, and 1,2-dichloroethane; ethers such as diethyl ether, dimethoxyethane, tetrahydrofuran, and dioxane; amides such as N,N-dimethylformamide and N,N-dimethylacetamide; nitriles such as acetonitrile, propionitrile, and benzonitrile; and alcohols such as methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, sec-butanol, and tert-butanol, preferably esters, aromatic hydrocarbons, ketones, and alcohols. One solvent can be used alone, or two or more solvents can be used in combination.

[0202] The concentration of the aforementioned crosslinking agent 11 and / or photopolymerization initiator 12 in solution 14 can be appropriately set, for example, from a range of 0.1 to 100% by weight, preferably 0.1 to 80% by weight, more preferably 1 to 70% by weight, more preferably 1.5 to 60% by weight, more preferably 3 to 50% by weight, and even more preferably 5 to 40% by weight. If the concentration of the crosslinking agent 11 and / or photopolymerization initiator 12 in solution 14 is within this range, the crosslinking agent 11 and / or photopolymerization initiator 12 can be dissolved and the adhesive layer 10b can be sufficiently swollen.

[0203] The concentration of the crosslinking agent 11 in solution 14 can be appropriately set, for example, from a range of 0.1 to 100 wt%, for example, below 95 wt% (e.g., 1 to 95 wt%, 1 to 90 wt%, 1 to 85 wt%, 1 to 80 wt%, 1 to 60 wt%, etc.), for example, above 1 wt% (e.g., 1 to 95 wt%, 2 to 95 wt%). When the concentration of the crosslinking agent is higher than the above range, the crosslinking agent 11 may sometimes seep out, or distribution deviations may occur from the viewpoint of coating uniformity. In addition, when the concentration is lower than the above range, the solvent required exceeds the demand, which may sometimes result in a decrease in adhesive properties due to residual solvent, or undesirable appearance conditions (called surface unevenness) due to the adhesive swelling beyond the demand.

[0204] The coating (coating) of the aforementioned solution 14 onto the adhesive layer 10b can be performed using known coating methods, such as gravure roller coating machines, reverse roller coating machines, licking coating machines, dip roller coating machines, bar coating machines, doctor blade coating machines, spray coating machines, comma coating machines, direct coating machines, and other coating machines.

[0205] The coating amount of solution 14 onto adhesive layer 10b can be appropriately set, for example, from 1 to 1000 μg / cm³. 2 Preferably, the concentration is 1–500 μg / cm³. 2 More preferably, 1–300 μg / cm 2 Further preferred values ​​are 1–100 μg / cm³ 2 The amount of solution 14 applied is selected from the range specified. If the amount of solution 14 applied is within this range, it can dissolve the crosslinking agent 11 and / or the photopolymerization initiator 12 and sufficiently impart the crosslinking agent 11 and / or the photopolymerization initiator 12 to the adhesive layer 10b.

[0206] After the solution 14 is applied to the adhesive layer 10b, it may be left standing as needed to allow the crosslinking agent 11 and / or the photoinitiator 12 to penetrate. The standing time is not particularly limited. For example, it can be appropriately selected within 15 minutes and can be selected from a range such as 1 second to 10 minutes, preferably 5 seconds to 5 minutes. The standing temperature can be carried out at room temperature (around 10 to 30 °C). When left standing under the above conditions, the crosslinking agent 11 and / or the photoinitiator 12 can penetrate sufficiently into the adhesive layer 10b.

[0207] The surface of the adhesive layer 10b swells by penetrating the solution 14. In this process, the crosslinking agent 11 and / or the photoinitiator 12 in the solution 14 penetrate along the thickness direction within the adhesive layer 10b (solution penetration step). This state is shown in Figure 2 (d). The crosslinking agent 11 and / or the photoinitiator 12 penetrate in a dissolved state in the adhesive layer 10b. Therefore, the crosslinking agent 11 and / or the photoinitiator 12 are in a "dissolved" state within the adhesive layer 10b.

[0208] In addition, during the process of the crosslinking agent 11 and / or the photoinitiator 12 penetrating into the adhesive layer 10b, a concentration gradient can be formed in the thickness direction. Therefore, the concentration of the crosslinking agent 11 and / or the photoinitiator 12 on the side where the solution 14 is applied can be higher than that on the opposite side. This state is shown in Figure 2 (d).

[0209] Then, by drying the adhesive layer 10b, the adhesive layer 10 shown in Figure 2 (e) can be obtained (drying step). When the solution 14 contains the solvent 13, the solvent 13 evaporates through the drying step. Through the drying step, the adhesive layer 10b returns to a state close to that before swelling. At the time point when the adhesive layer 10b is dried, the penetration of the crosslinking agent 11 and / or the photoinitiator 12 into the adhesive layer 10b stops, and the concentration gradient of the aforementioned crosslinking agent 11 and / or photoinitiator 12 is fixed.

[0210] The heating drying temperature in the drying step is preferably 40 to 200 °C, more preferably 50 to 180 °C, and further preferably 60 to 170 °C. The drying time can be an appropriate and suitable time, for example, 5 seconds to 20 minutes, preferably 5 seconds to 10 minutes, and more preferably 10 seconds to 5 minutes. By drying under the above conditions, the adhesive layer 10 can return to a state close to that before coating.

[0211] Additionally, a settling time can be set as needed to further homogenize the crosslinking agent and adhesive layer. There is no particular limitation on the settling time; for example, it can be appropriately selected from within 30 days, or from 1 hour to 15 days, preferably from 24 hours to 10 days. Through settling, the crosslinking agent and adhesive layer of the adhesive layer 10 are stabilized, suppressing deviations in performance evaluation.

[0212] Figure 2 The photocurable adhesive sheet 1B shown in (e) is one embodiment of the photocurable adhesive sheet A containing an adhesive layer 10, which is composed of a mixed adhesive composition containing a base polymer, a crosslinking agent 11 and a photopolymerization initiator 12.

[0213] In the aforementioned second embodiment, the base polymer contains a first crosslinking agent and a first polymerization initiator as the first initiator, and the aforementioned adhesive layer curing process is a curing based on the reaction of the first crosslinking agent and the first polymerization initiator. The crosslinking agent 11 and the photopolymerization initiator 12 become the second initiators.

[0214] After the aforementioned adhesive layer curing process, sometimes one or both of the first crosslinking agent and the first polymerization initiator may remain. In this case, only one of the second crosslinking agent and the second polymerization initiator may be used as crosslinking agent 11 and photopolymerization initiator 12, and it is preferable to use only the second crosslinking agent (crosslinking agent 11). However, both the second crosslinking agent and the second polymerization initiator may also be used.

[0215] In the second embodiment described above, the combination of the first initiator and the second initiator offers a wide degree of freedom. That is, there are no restrictions on the combination of polymerization initiators; for example, it is possible to freely choose a combination where both the first and second initiators are photopolymerization initiators, or a combination where the first initiator is a thermal polymerization initiator and the second initiator is a photopolymerization initiator. Furthermore, when both the first and second initiators are photopolymerization initiators, the light absorption wavelength bands of the two photopolymerization initiators may overlap or be similar. Moreover, it is also possible to create a combination where the first and second initiators are the same polymerization initiator, which is impossible for conventional mixed adhesive sheets.

[0216] Furthermore, there are no restrictions on the combination of crosslinking agents; it is also possible for the first initiator and the second initiator to be the same crosslinking agent.

[0217] Figure 3 (a) is a cross-sectional view showing one embodiment of the photocurable adhesive sheet A of the present invention. Figure 3 (b) is a cross-sectional view showing another embodiment of the photocurable adhesive sheet A of the present invention.

[0218] See Figure 3(a) In one embodiment of the present invention, the photocurable adhesive sheet 1C is composed of an adhesive layer 10 and a support S1, wherein one side of the adhesive layer 10, namely the first main side 10A, is not attached to the support, and the support S1 is formed by a release sheet attached to the other side of the adhesive layer 10, namely the second main side 10B.

[0219] See Figure 3 (b) In one embodiment of the present invention, the photocurable adhesive sheet 1D comprises an adhesive layer 10, a first support S2 formed by a release liner adhered to one side of the adhesive layer 10, namely the first main surface 10A, and a second support S1 formed by a release liner adhered to the other side of the adhesive layer 10, namely the second main surface 10B. The photocurable adhesive sheet 1D can be obtained by adhering the support S2 to the first main surface 10A of the photocurable adhesive sheet 1C.

[0220] Figure 3 In (a) and (b), the dashed line X-X' is the line that divides the adhesive layer 10 into two equal parts along the thickness direction. When the thickness of the adhesive layer 10 is not uniform, the dashed line X-X' is the line that divides the thickness of each location into two equal parts.

[0221] Figure 3 In this process, the adhesive layer 10 is a single layer formed from a base polymer and having two opposing main surfaces (a first main surface and a second main surface). The adhesive layer 10 can be formed by the method described in the second embodiment above, which is equivalent to... Figure 2 Adhesive layer 10.

[0222] The term "single layer" in adhesive layer designation means that it is not a laminated structure. For example, a structure that forms an adhesive layer of a base polymer and then further forms another adhesive layer of the same base polymer on top of it is a laminated structure, not a single layer. Similarly, a structure that forms an adhesive layer of a base polymer containing a crosslinking agent and / or a photopolymerization initiator and then further forms another adhesive layer on top of it composed of base polymers containing crosslinking agents and / or photopolymerization initiators dissolved in different concentrations is a laminated structure, not a single layer.

[0223] The thickness of the adhesive layer 10 is not particularly limited, but is typically 5 μm to 500 μm, preferably 5 μm to 400 μm, and more preferably 5 μm to 350 μm. A thickness within this range is suitable for forming a concentration gradient of crosslinking agent and / or photopolymerization initiator along the thickness direction of the adhesive layer 10.

[0224] Regarding the crosslinking agent 11 and / or photopolymerization initiator 12, through the aforementioned solution coating process, solution penetration process, and drying process, the crosslinking agent 11 and / or photopolymerization initiator 12 penetrate into the adhesive layer 10, thereby forming, as shown in the figure. Figure 3As shown, a concentration gradient of crosslinking agent 11 and / or photopolymerization initiator 12 can be generated along the thickness direction of adhesive layer 10. Therefore, when a single layer of adhesive layer 10 is divided into two equal parts along its thickness direction, the concentration of the aforementioned crosslinking agent 11 and / or photopolymerization initiator 12 in the region belonging to one of the aforementioned two main surfaces, namely the first main surface 10A, differs from the concentration of the aforementioned crosslinking agent 11 and / or photopolymerization initiator 12 in the region belonging to the other, namely the second main surface 10B. The absence of crosslinking agent 11 and / or photopolymerization initiator 12 in regions with lower concentrations (concentration of 0) is also included within the scope of this invention.

[0225] When the aforementioned concentrations in the region to which the first main surface belongs and the aforementioned concentrations in the region to which the second main surface belongs also have concentration gradients within their respective regions, it refers to the average concentration of crosslinking agent 11 and / or photopolymerization initiator 12 within their respective regions.

[0226] Figure 3 (a) illustrates the following embodiment: On the support S1, the concentration of the crosslinking agent 11 and / or photopolymerization initiator 12 in the region to which the first main surface 10A belongs is higher than the concentration of the crosslinking agent 11 and / or photopolymerization initiator 12 in the region to which the second main surface 10B belongs can be obtained by coating the first main surface 10A with a solution of crosslinking agent 11 and / or photopolymerization initiator 12, and from the first main surface 10A, the crosslinking agent 11 and / or photopolymerization initiator 12 penetrates into the adhesive layer 10 in a dissolved state throughout the entire depth in the thickness direction.

[0227] The adhesive layer 10 generates a concentration gradient of crosslinking agent 11 and / or photopolymerization initiator 12 in the thickness direction, resulting in a difference in crosslinking density between the surface and the back side during the curing of the adhesive layer 10. That is, in Figure 3 In this configuration, the area belonging to the main surface 10A can achieve a higher crosslinking density than the area belonging to the main surface 10B. This configuration is preferred, for example, in the case where the photocurable adhesive sheet A is used as a flexible image display device in which one side of the main surface 10A is bent outwards, from the perspective of improved flexibility. That is, when a flexible display is bent, tensile stress is typically applied to the outer side and compressive stress is applied to the inner side, with the stress on the outer side being stronger than that on the inner side. Therefore, by positioning the main surface 10A of the adhesive layer 10 on the outer side when the flexible display is bent, the durability against bending can be improved.

[0228] As another third embodiment of the mixed adhesive composition constituting adhesive layer A, an adhesive composition (hereinafter sometimes referred to as "BP-type mixed adhesive composition") containing a polymer having a benzophenone structure in its side chain is also provided. The "benzophenone structure" functions as a second initiator in the mixed adhesive.

[0229] Suitable examples of BP polymers include acrylic polymers having a benzophenone structure in the side chain. Preferably, the BP polymers described above are polymers that substantially do not contain olefinic unsaturated groups.

[0230] In this specification, "benzophenone structure" refers to the general formula: Ar 1 -(C=O)-Ar 2 -; or -Ar 3 -(C=O)-Ar 2 - The diaryl ketone structure shown. Here, Ar in the above general formula 1 Ar is selected from phenyl groups that have optional substituents. 2 Ar 3 Each is independently selected from phenylene oxides with optional substituents. Ar 2 and Ar 3 They can be the same or different. The benzophenone structure can be excited by ultraviolet light, and in this excited state, it can abstract hydrogen radicals from other molecules or other parts of the molecule.

[0231] The adhesive layer formed from the aforementioned BP-type mixed adhesive composition contains a polymer (BP polymer) with a benzophenone structure in its side chains, thereby enabling the formation of a cross-linked structure through the hydrogen radical abstraction reaction by activating this benzophenone structure. Preferably, the polymer with a benzophenone structure in its side chains is of the following general formula: Ar 1 -(C=O)-Ar 2 Ar in 1 The phenyl group is optionally substituted, and Ar 2 The above Ar is a polymer having a benzophenone structure on the side chain, optionally containing substituted phenylene groups. 1 and Ar 2 When at least one of them has one or more substituents, each substituent may be independently selected from the group consisting of alkoxy groups (e.g., alkoxy groups with 1 to 3 carbon atoms, preferably methoxy groups), halogen atoms (e.g., F, Cl, Br, etc., preferably Cl or Br), hydroxyl groups, amino groups, and carboxyl groups.

[0232] The aforementioned BP polymers can have side chains that are directly bonded to the main chain via the benzophenone structure as described above, or they can have side chains that are bonded to the main chain via one or more of the following: ester bonds, oxoalkylene structures, etc. Suitable examples of BP polymers include polymers comprising repeating units derived from compounds having an olefinic unsaturated group and a benzophenone structure in the molecule (hereinafter sometimes referred to as "olefinic unsaturated BP"). These repeating units can be polymeric residues obtained by reacting the olefinic unsaturated group of the corresponding olefinic unsaturated BP.

[0233] Examples of olefinically unsaturated BPs include: 4-acryloyloxybenzophenone, 4-acryloyloxy-4'-methoxybenzophenone, 4-acryloyloxyethoxy-4'-methoxybenzophenone, 4-acryloyloxy-4'-bromobenzophenone, 2-hydroxy-4-acryloyloxybenzophenone, and other acryloyloxybenzophenones optionally having substituents; 4-[(2-acryloyloxy)ethoxy]benzophenone, 4-[(2-acryloyloxy)ethoxy]-4'-bromobenzophenone, and other acryloyloxyalkoxybenzophenones optionally having substituents; 4-methacryloyloxybenzophenone, 4-methacryloyloxy-4'-methoxybenzophenone, etc. 4-Methacryloxy-4'-bromobenzophenone, 4-methacryloyloxyethoxy-4'-bromobenzophenone, 2-hydroxy-4-methacryloyloxybenzophenone, and other optionally substituted methacryloyloxybenzophenones; 4-[(2-methacryloyloxy)ethoxy]benzophenone, 4-[(2-methacryloyloxy)ethoxy]-4'-methoxybenzophenone, and other optionally substituted methacryloyloxyalkoxybenzophenones; 4-vinylbenzophenone, 4'-bromo-3-vinylbenzophenone, 2-hydroxy-4-methoxy-4'-vinylbenzophenone, and other optionally substituted vinylbenzophenones, etc., but not limited to these. Alkene-unsaturated BP can be used alone or in combination of two or more for the preparation of BP polymers. Alkene-unsaturated BP can be synthesized using commercially available substances or by known methods. From the perspective of reactivity, olefin unsaturated BP with (meth)acryloyl group, i.e. olefin unsaturated BP belonging to the acrylic monomer group, can be preferred.

[0234] The aforementioned BP polymer can be a copolymer having repeating units derived from olefinically unsaturated BP and repeating units derived from olefinically unsaturated compounds that are not olefinically unsaturated BP (hereinafter also referred to as "other olefinically unsaturated compounds"). Such a BP polymer can be a copolymer comprising monomer components of the aforementioned olefinically unsaturated BP and the aforementioned other olefinically unsaturated compounds. Alternatively, the aforementioned BP polymer can also be a copolymer obtained by copolymerizing a portion of a monomer mixture (prepolymer) consisting only of the aforementioned other olefinically unsaturated compounds with the aforementioned olefinically unsaturated BP. As the aforementioned other olefinically unsaturated compounds, one or more acrylic monomers are preferably used. As a suitable example of a BP polymer, an acrylic BP polymer in which more than 50% by weight (preferably more than 70% by weight, for example more than 90% by weight) of the monomer components constituting the BP polymer are acrylic monomers can be cited.

[0235] For the acrylic monomers that are the other olefinic unsaturated compounds mentioned above, the same monomers as the alkyl acrylates having straight-chain or branched alkyl groups that constitute the monomer units of the acrylic polymers mentioned above can be used. The monomer components constituting the BP polymer may also include one or more of the alicyclic monomers, hydroxyl-containing monomers, nitrogen-containing monomers, and carboxyl-containing monomers selected from the monomer units constituting the acrylic polymers mentioned above as the other olefinic unsaturated compounds mentioned above.

[0236] The aforementioned BP-type mixed adhesive composition can be a photocurable acrylic adhesive composition in which more than 50% by weight (preferably more than 70% by weight, for example more than 90% by weight) of all constituent monomer components are acrylic monomers. The photocurable acrylic adhesive composition forms an acrylic photocurable product by photocuring.

[0237] The weight-average molecular weight (Mw) of BP polymers is not particularly limited; for example, it can be 0.5 × 10⁻⁶. 4 ~500×10 4 Approximately. From the perspectives of the cohesiveness of adhesive layer A and the processability of the photocurable adhesive sheet A, the Mw of the aforementioned BP polymer is typically 1 × 10⁻⁶. 4 The above is appropriate, and preferably 5×10 4 The above can be 10×10 4 The above can be 15×10 4 The above, or 20×10 4 That's all. Furthermore, from the viewpoint of the height difference absorption of adhesive layer A, the Mw of the BP polymer is typically 200 × 10⁻⁶. 4 The following is appropriate, preferably 150×10 4 The following can be 100×10 4 The following can be 70×10 4The following can also be 50×10 4 the following.

[0238] It should be noted that the weight-average molecular weight (Mw) of the polymer refers to the value converted from standard polystyrene obtained by gel permeation chromatography (GPC). For example, a GPC device named "HLC-8320GPC" (column: TSKgelGMH-H(S), manufactured by Tosoh Corporation) can be used.

[0239] The glass transition temperature (Tg) of the aforementioned BP polymer is not particularly limited. For example, the Tg of the BP polymer can be -80°C or higher and 150°C or lower, -80°C or higher and 50°C or lower, or -80°C or higher and 10°C or lower. From the viewpoint of the height difference absorption of the adhesive layer A, a Tg below 0°C is suitable, preferably below -10°C, below -20°C, below -30°C, below -40°C, or below -50°C. Furthermore, from the viewpoint of improved cohesiveness of the adhesive layer A and improved processability after photocuring, a Tg of -75°C or higher for the BP polymer is generally advantageous, and can also be -70°C or higher. In some embodiments, the Tg of the BP polymer can be -55°C or higher, or -45°C or higher. The Tg of the BP polymer can be adjusted by the type and amount of monomer components constituting the BP polymer.

[0240] Here, the glass transition temperature (Tg) of the polymer refers to the glass transition temperature determined by the Fox formula based on the composition of the monomers constituting the polymer. The Fox formula, as shown below, is the relationship between the Tg of the copolymer and the glass transition temperature Tgi of the homopolymer formed by homopolymerizing each of the monomers constituting the copolymer.

[0241] 1 / Tg=Σ(Wi / Tgi)

[0242] It should be noted that in the above Fox formula, Tg represents the glass transition temperature of the copolymer (unit: K), Wi represents the weight fraction of monomer i in the copolymer (weight-based copolymerization ratio), and Tgi represents the glass transition temperature of the homopolymer of monomer i (unit: K).

[0243] The glass transition temperature of the homopolymer used in the calculation of Tg is the value recorded in known sources. For example, for the monomers listed below, the following values ​​are used as the glass transition temperatures of the homopolymers of those monomers.

[0244] 2-Ethylhexyl acrylate: -70℃

[0245] n-Butyl acrylate: -55℃

[0246] Isostearyl acrylate: -18℃

[0247] Methyl methacrylate: 105℃

[0248] Methyl acrylate: 8℃

[0249] Cyclohexyl acrylate: 15℃

[0250] N-Vinyl-2-pyrrolidone: 54℃

[0251] 2-Hydroxyethyl acrylate: -15℃

[0252] 4-Hydroxybutyl acrylate: -40℃

[0253] Isoborneol acrylate: 94℃

[0254] Acrylic acid: 106℃

[0255] Methacrylic acid: 228℃

[0256] For the glass transition temperatures of homopolymers of monomers other than those listed above, the values ​​recorded in the "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) are used. If multiple values ​​are recorded in this document, the highest value is adopted. For monomers whose homopolymer glass transition temperatures are not recorded in the aforementioned Polymer Handbook, the values ​​obtained by the determination method described in Japanese Patent Application Publication No. 2007-51271 are used. It should be noted that for polymers for which nominal values ​​of glass transition temperatures are provided by manufacturers, these nominal values ​​may also be used.

[0257] Preferably, the BP polymer contains, for example, about 0.5 mg or more of benzophenone structures converted from 4-benzoylphenyl acrylate per 1 g of the polymer. Hereinafter, the value obtained by converting the number of benzophenone structures per 1 g of BP polymer to the equivalent amount of 4-benzoylphenyl acrylate is referred to as the BP equivalent (unit: mg / g) of the BP polymer. For example, when each 1 g contains 40 μmol of benzophenone structures, the BP equivalent of the polymer is calculated to be 10 mg / g.

[0258] From the viewpoint of achieving a higher photocuring effect (e.g., improved processability through photocuring), in some embodiments, it is suitable that the BP equivalent of the BP polymer is typically 0.11 mg / g or more, and can be 0.5 mg / g or more, 1 mg / g or more, 5 mg / g or more, 8 mg / g or more, 10 mg / g or more, 15 mg / g or more, or 20 mg / g or more. Furthermore, in some embodiments, from the viewpoint of improving the impact resistance and peel strength of the bond based on the photocured material, it is suitable that the BP equivalent of the BP polymer is typically 100 mg / g or less, and can be 80 mg / g or less, 60 mg / g or less, 40 mg / g or less, 25 mg / g or less, or 15 mg / g or less. The BP equivalent of the BP polymer can be adjusted by the composition of the monomer components constituting the BP polymer.

[0259] Based on this, from the perspective of reducing peel force through photocuring, enabling reprocessing and repair, the BP equivalent is preferably 50 mg / g or more, or it can be 100 mg / g or more.

[0260] The weight percentage of BP polymer in the overall BP-type mixed adhesive composition, i.e., the weight fraction of BP polymer in the BP-type mixed adhesive composition, is not particularly limited and can be set in a way that appropriately balances the height difference absorbency of adhesive layer A with the processability of its UV-cured product. In some embodiments, the weight fraction of the BP polymer can be, for example, 1% by weight or more, typically 5% by weight or more, 10% by weight or more, 15% by weight or more, 25% by weight or more, 35% by weight or more, 45% by weight or more, or 55% by weight or more. As the weight fraction of the BP polymer increases, there is a tendency for the aforementioned G'a10 / G'b85 to increase.

[0261] It can also be implemented in such a way that the weight fraction of the BP polymer in the BP-type mixed adhesive composition is substantially 100% by weight (e.g., 99.5% by weight or more). Furthermore, from the viewpoint of ease of adhesion, in some embodiments, the weight fraction of the BP polymer in the BP-type mixed adhesive composition may be, for example, less than 99% by weight, less than 95% by weight, less than 85% by weight, less than 70% by weight, less than 50% by weight, or less than 40% by weight.

[0262] Preferred to be benzoyl acrylate, each 1g of BP-type mixed adhesive composition preferably contains, for example, about 0.1mg or more of benzophenone structure. Hereinafter, the weight of 4-benzoyl acrylate containing benzophenone structure per 1g of BP-type mixed adhesive composition is sometimes referred to as the BP equivalent (unit: mg / g) of the BP-type mixed adhesive composition. From the viewpoint of obtaining a higher photocuring effect (e.g., improved processability through photocuring), in some embodiments, it is suitable that the BP equivalent of the BP-type mixed adhesive composition is typically 0.3mg / g or more, and can be 0.5mg / g or more, 1mg / g or more, 5mg / g or more, 10mg / g or more, or 20mg / g or more. In addition, in some embodiments, from the viewpoint of impact resistance of the joint based on the UV-cured material and suppression of strain within the UV-cured material, it is appropriate that the BP equivalent of the BP-type mixed adhesive composition is generally less than 100 mg / g, and may be less than 80 mg / g, less than 60 mg / g, less than 40 mg / g, less than 25 mg / g, or less than 15 mg / g.

[0263] The aforementioned BP-type mixed adhesive composition may be an adhesive composition comprising an olefinic unsaturated compound and a BP polymer. Alternatively, the aforementioned BP-type mixed adhesive composition may be an acrylic adhesive composition in which more than 50% by weight (preferably more than 70% by weight, for example more than 90% by weight) of all monomeric components constituting the adhesive composition are acrylic monomers.

[0264] As the aforementioned olefinic unsaturated compounds, the same compounds as the alkyl acrylates, alicyclic monomers, hydroxyl-containing monomers, nitrogen-containing monomers, carboxyl-containing monomers, and polyfunctional (meth)acrylates that constitute the monomer units of the aforementioned acrylic polymers can be used.

[0265] The olefin unsaturated compound may contain alkyl acrylates at a ratio of 40% by weight or more. The percentage of alkyl acrylates in the monomer component may be, for example, 50% by weight or more, 60% by weight or more, or 65% by weight or more. Furthermore, from the viewpoint of improving the cohesiveness of adhesive layer A, it is generally appropriate to set the percentage of alkyl acrylates in the olefin unsaturated compound to be 99.5% by weight or less, and may be 95% by weight or less, 85% by weight or less, 70% by weight or less, or 60% by weight or less.

[0266] There is no particular limitation on the amount of alicyclic monomers used; for example, it can be set to 1% or more, 3% or more, or 5% or more of the total monomer composition. In one embodiment, the amount of alicyclic monomers used can be 10% or more, or 15% or more of the total monomer composition. It is appropriate to set the upper limit of the amount of alicyclic monomers used to about 40% or less, for example, 30% or less, or 25% or less (e.g., 15% or less, and further 10% or less). Alternatively, alicyclic monomers may not be used as the aforementioned olefinic unsaturated compounds.

[0267] There is no particular limitation on the amount of nitrogen-containing monomer used; for example, it can be 1% or more, 2% or more, 3% or more, 5% or more, or 7% or more of the total monomer composition. In one embodiment, the amount of nitrogen-containing monomer used can be 10% or more, 15% or more, or 20% or more of the total monomer composition. Alternatively, it is appropriate to set the amount of nitrogen-containing monomer used to be, for example, 40% or less of the total monomer composition, and it can be set to 35% or less, 30% or less, or 25% or less. In another embodiment, the amount of nitrogen-containing monomer used can be, for example, 20% or less, or 15% or less of the total monomer composition. Alternatively, nitrogen-containing monomers may not be used in the aforementioned olefinic unsaturated compounds.

[0268] There is no particular limitation on the amount of hydroxyl-containing monomer used. For example, it can be 0.01% or more by weight of the total monomer composition, 0.1% or more by weight, 0.5% or more by weight, 1% or more by weight, 5% or more by weight, or 10% or more by weight. Furthermore, from the viewpoint of suppressing water absorption of the BP-type mixed adhesive composition or adhesive layer A, in some embodiments, it is appropriate to set the amount of hydroxyl-containing monomer used to be, for example, 40% or less by weight of the total monomer composition, and it can be set to 30% or less by weight, 25% or less by weight, or 20% or less by weight. In another embodiment, the amount of hydroxyl-containing monomer used can be set to, for example, 15% or less by weight, 10% or less by weight, or 5% or less by weight of the total monomer composition. Alternatively, the hydroxyl-containing monomer may not be used as the aforementioned olefinic unsaturated compound.

[0269] There are no particular restrictions on the amount of carboxyl-containing monomers used; their proportion in the total monomer composition can be, for example, less than 2% by weight, less than 1% by weight, or less than 0.5% by weight (e.g., less than 0.1% by weight). BP-type mixed adhesive compositions may also be substantially free of carboxyl-containing monomers as constituent monomer components. Here, "substantially free of carboxyl-containing monomers" means, at least intentionally, not using carboxyl-containing monomers. This can be advantageous from the viewpoint of the adhesive layer A formed by the BP-type mixed adhesive composition and the metal corrosion prevention of its UV-cured product.

[0270] The amount of multifunctional (meth)acrylate used is not particularly limited and can be set to less than 5.0% by weight of all monomer components constituting the BP-type mixed adhesive composition. This avoids the formation of excessive cross-linking structures during the formation of adhesive layer A (i.e., the stage before photocuring), thereby improving the height difference absorption of adhesive layer A. The amount of multifunctional (meth)acrylate used can be, for example, less than 4.0% by weight of all monomer components, less than 3.0% by weight, less than 2.0% by weight, less than 1.0% by weight, less than 0.5% by weight, or less than 0.3% by weight. Multifunctional (meth)acrylate may also be omitted. Furthermore, in some embodiments, from the viewpoint of imparting appropriate cohesiveness to adhesive layer A, the amount of multifunctional (meth)acrylate used relative to all monomer components can be, for example, more than 0.001% by weight, more than 0.005% by weight, more than 0.01% by weight, or more than 0.03% by weight. Alternatively, polyfunctional (meth)acrylates may not be used as the aforementioned olefinic unsaturated compounds.

[0271] The weight ratio of the BP polymer in the total amount of BP polymer and olefin unsaturated compound contained in the BP-type mixed adhesive composition is not particularly limited, and can be set in a way that appropriately balances the height difference absorption of the adhesive layer A formed by the adhesive composition with the processability of its photocured product. In some embodiments, the weight fraction of the BP polymer can be, for example, 0.5% by weight or more, typically 1% by weight or more, preferably 1.5% by weight or more, and more preferably 5% by weight or more. From the viewpoint of improving the photocuring effect, it can be 10% by weight or more, 15% by weight or more, 25% by weight or more, 35% by weight or more, 45% by weight or more, or 55% by weight or more. In addition, from the viewpoint of ease of preparation and coatability of the adhesive composition, in some embodiments, the weight ratio of the BP polymer in the above total amount can be, for example, less than 99% by weight, less than 95% by weight, less than 85% by weight, less than 70% by weight, less than 50% by weight, or less than 40% by weight.

[0272] The weight percentage of the organic solvent in the total weight of the BP-type mixed adhesive composition can be, for example, 30% by weight or less, preferably 20% by weight or less, more preferably 10% by weight or less, and more preferably 5% by weight or less. In some embodiments, the weight percentage of the organic solvent can be 3% by weight or less, 1% by weight or less, 0.5% by weight or less, 0.1% by weight or less, 0.05% by weight or less, or may be substantially free of organic solvent.

[0273] From the viewpoint of coatability in the aforementioned room temperature range, it is appropriate for the viscosity of the aforementioned BP-type mixed adhesive composition (measured using a BH type viscometer, No. 5 rotor, at 10 rpm and a measurement temperature of 30°C. The same applies below) to be 1000 Pa·s or less, preferably 100 Pa·s or less, and more preferably 50 Pa·s or less. The viscosity of the aforementioned BP-type mixed adhesive composition can, for example, be 30 Pa·s or less, 20 Pa·s or less, 10 Pa·s or less, or 5 Pa·s or less. There is no particular limitation on the lower limit of the viscosity of the BP-type mixed adhesive composition. From the viewpoint of suppressing pinholes in the adhesive composition within the coating area and overflow of the adhesive composition at the outer edge of the coating area, it is generally appropriate for it to be 0.1 Pa·s or more, and can be 0.5 Pa·s or more, or even 1 Pa·s or more.

[0274] The aforementioned BP-type mixed adhesive composition may contain at least one compound having one olefin unsaturated group (i.e., a monofunctional monomer) as the aforementioned olefin unsaturated compound. The monofunctional monomer may be selected from the examples of the aforementioned olefin unsaturated compounds. One monofunctional monomer may be used alone, or two or more may be used in combination.

[0275] In the total amount of BP polymer and olefin unsaturated compound, the weight ratio of monofunctional monomers can be, for example, 1% or more by weight, 5% or more by weight, or 15% or more by weight. In some embodiments, from the viewpoint of ease of preparation and coatability of BP-type mixed adhesive compositions, the weight ratio of the aforementioned monofunctional monomers can be 25% or more by weight, 35% or more by weight, or 45% or more by weight. Furthermore, in the aforementioned total amount, the weight ratio of monofunctional monomers can be, for example, 99% or less by weight, typically 95% or less by weight is suitable, and can be 85% or less by weight, 75% or less by weight, 65% or less by weight, 55% or less by weight, or 45% or less by weight.

[0276] In BP-type hybrid adhesive compositions containing monofunctional monomers, the glass transition temperature (Tg) calculated using the Fox formula based on the composition of the monofunctional monomer is not particularly limited, and can be, for example, above -80°C and below 250°C. From the viewpoint of the compatibility of the polymer derived from the monofunctional monomer with other components, the Tg based on the composition of the monofunctional monomer is generally preferably below 150°C, but can be below 100°C, below 70°C, below 50°C, or below 30°C. In some embodiments, from the viewpoint of the height difference absorption of adhesive layer A, the Tg based on the composition of the monofunctional monomer is preferably below 0°C, more preferably below -10°C, below -20°C, below -30°C, or below -40°C. Furthermore, from the viewpoint of the cohesiveness of adhesive layer A and the processability after photocuring, it is advantageous for the temperature gradient (Tg) of the monofunctional monomer composition to be generally above -60°C, but it can be above -54°C, above -50°C, above -45°C, above -35°C, or above -25°C. The aforementioned Tg can be adjusted by the compounds used as monofunctional monomers and their dosage ratios.

[0277] In a BP-type mixed adhesive composition comprising a BP polymer and a monofunctional monomer, an adhesive layer A formed from the adhesive composition, and a photocurable thereof, the Tg (hereinafter referred to as "Tg") of the BP polymer is... A Tg (hereinafter referred to as "Tg") is composed of monomers based on monofunctional monomers. B1 ") can be accessed via Tg B1 [℃]-Tg A The Tg difference [°C] (hereinafter also referred to as ΔTg) calculated from [°C] is set in a range, for example, from -50°C to 70°C. From the viewpoint of compatibility between adhesive layer A and its photocurable material, it is advantageous that the absolute value of the above-mentioned Tg difference is not too large. In some embodiments, ΔTg can be, for example, -10°C or more, preferably 0°C or more, 7°C or more, 10°C or more, 20°C or more, or 30°C or more.

[0278] The aforementioned BP-type mixed adhesive composition may contain at least a compound having two or more olefinic unsaturated groups (i.e., a polyfunctional monomer) as the aforementioned olefinic unsaturated compound. The polyfunctional monomer may be used alone or in combination with two or more examples of the aforementioned polyfunctional monomers. The amount of polyfunctional monomer used may be set in the same manner as the ratio of the polyfunctional (meth)acrylate to the total monomer components constituting the adhesive composition.

[0279] In the combination of monofunctional and polyfunctional monomers as olefinic unsaturated compounds, the weight percentage of the monofunctional monomer in the olefinic unsaturated compound can be, for example, 1% by weight or more, typically 25% by weight or more, and can be 50% by weight or more, 75% by weight or more, 95% by weight or more, or 99% by weight or more. Furthermore, the weight percentage of the monofunctional monomer in the olefinic unsaturated compound can be, for example, 99.9% by weight or less, or 99.8% by weight or less.

[0280] In the aforementioned BP-type mixed adhesive composition, the olefinic unsaturated compound may be contained in the form of a partial polymer or entirely in the form of unreacted monomers. A preferred embodiment of the adhesive composition contains the olefinic unsaturated compound in the form of a partial polymer. There are no particular limitations on the polymerization method used to partially polymerize the olefinic unsaturated compound; for example, photopolymerization by irradiation with ultraviolet light, radiation polymerization by irradiation with beta rays, gamma rays, or other radiation, thermal polymerization such as solution polymerization, emulsion polymerization, and bulk polymerization, and other conventionally known polymerization methods can be appropriately selected. From the viewpoint of efficiency and simplicity, photopolymerization is preferred. Using photopolymerization, the polymerization conversion rate (monomer conversion rate) can be easily controlled by polymerization conditions such as the amount of light irradiation (light intensity).

[0281] The polymerization conversion rate of the olefinic unsaturated compounds in the aforementioned polymers is not particularly limited. From the viewpoint of ease of preparation and coatability of the adhesive composition, a polymerization conversion rate of about 50% by weight or less is generally suitable, preferably about 40% by weight or less (e.g., about 35% by weight or less). There is no particular limitation on the lower limit of the polymerization conversion rate, which is typically about 1% by weight or more, and is generally suitable to be about 5% by weight or more.

[0282] A BP-type mixed adhesive composition containing a partial polymer of an olefinic unsaturated compound can be obtained, for example, by partially polymerizing a monomer mixture containing the entire amount of the olefinic unsaturated compound used in the preparation of the adhesive composition using a suitable polymerization method (e.g., photopolymerization). Alternatively, the BP-type mixed adhesive composition containing a partial polymer of an olefinic unsaturated compound can also be a mixture of a partial polymer of a monomer mixture containing a portion of the olefinic unsaturated compound used in the preparation of the adhesive composition and the remaining olefinic unsaturated compound or a partial polymer thereof. It should be noted that, in this specification, "complete polymer" means a polymerization conversion rate greater than 95% by weight.

[0283] The aforementioned partial polymers can be prepared, for example, by irradiating an olefinically unsaturated compound with ultraviolet light. When preparing the aforementioned partial polymer in the presence of a BP polymer, the ultraviolet irradiation conditions are set in a manner that allows the olefinically unsaturated groups to react while preventing photoexcitation of the benzophenone structure. This allows the acquisition of an adhesive composition containing both the olefinically unsaturated compound and the BP polymer. As the light source, a black light lamp, UV-LED lamp, or similar light source capable of irradiating ultraviolet light containing components with wavelengths below 300 nm or with minimal components of that wavelength is preferably used.

[0284] Alternatively, a partial polymer of the olefin unsaturated compound can be prepared in advance, and then the partial polymer can be mixed with the BP polymer to prepare an adhesive composition. When preparing a partial polymer of the olefin unsaturated compound by irradiating it with ultraviolet light in the absence of components containing the benzophenone structure, both light sources that do not excite the benzophenone structure and light sources that do excite the benzophenone structure can be used as the ultraviolet light source.

[0285] When preparing partial polymers of olefinically unsaturated compounds, the reaction of the olefinically unsaturated groups can be promoted by using a photopolymerization initiator. As photopolymerization initiators, ketal-based photopolymerization initiators, acetophenone-based photopolymerization initiators, benzoin ether-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, α-keto alcohol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzoyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, alkylphenyl ketone-based photopolymerization initiators, thioxanone-based photopolymerization initiators, etc., are preferred. Photopolymerization initiators that absorb light with wavelengths above 300 nm (e.g., light with wavelengths above 300 nm and below 500 nm) and generate free radicals are preferably used. One photopolymerization initiator can be used alone or in appropriate combinations of two or more.

[0286] The aforementioned BP-type mixed adhesive composition may contain a photopolymerization initiator as needed, for purposes such as improving or imparting photocurability. As photopolymerization initiators, ketal-based photopolymerization initiators, acetophenone-based photopolymerization initiators, benzoin ether-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, α-keto alcohol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzoyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, alkylphenyl ketone-based photopolymerization initiators, thioxanone-based photopolymerization initiators, etc., may be used alone or in appropriate combinations of two or more.

[0287] Specific examples of ketal-based photopolymerization initiators include 2,2-dimethoxy-1,2-diphenylethane-1-one, etc.

[0288] Specific examples of acetophenone-based photopolymerization initiators include: 1-hydroxycyclohexylphenyl-one, 4-phenoxydichloroacetophenone, 4-tert-butyldichloroacetophenone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane-1-one, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, methoxyacetophenone, etc.

[0289] Specific examples of benzoin ether-based photopolymerization initiators include: benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and other substituted benzoin ethers such as anisolein methyl ether.

[0290] Specific examples of acylphosphine oxide photopolymerization initiators include: bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,4-di-n-butoxyphenylphosphine oxide, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, etc.

[0291] Specific examples of α-keto alcohol-based photopolymerization initiators include: 2-methyl-2-hydroxyphenylacetone, 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropane-1-one, etc.

[0292] Specific examples of aromatic sulfonyl chloride photopolymerization initiators include 2-naphthalenesulfonyl chloride, etc.

[0293] Specific examples of photoactive oxime photopolymerization initiators include 1-phenyl-1,1-propanedione-2-(O-ethoxycarbonyl)-oxime.

[0294] Specific examples of benzoin-based photopolymerization initiators include benzoin itself.

[0295] Specific examples of benzoyl photopolymerization initiators include benzoyl and others.

[0296] Specific examples of benzophenone-based photopolymerization initiators include: benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexylphenyl ketone, etc.

[0297] Specific examples of thioxanthone-based photopolymerization initiators include: thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone, etc.

[0298] As a photopolymerization initiator contained in a BP-type hybrid adhesive composition, a photopolymerization initiator that absorbs light with a wavelength of 300 nm or higher (e.g., light with a wavelength of 300 nm or higher but less than 500 nm) and generates free radicals is preferably used. One photopolymerization initiator may be used alone or in a suitable combination of two or more. In some embodiments, a photopolymerization initiator that does not contain phosphorus in its molecule is preferably used. The BP-type hybrid adhesive composition may substantially not contain a photopolymerization initiator that contains phosphorus in its molecule.

[0299] The content of the photopolymerization initiator in the aforementioned BP-type hybrid adhesive composition is not particularly limited and can be set in a manner that appropriately achieves the desired effect. In some embodiments, the content of the photopolymerization initiator relative to 100 parts by weight of the monomer components constituting the BP-type hybrid adhesive composition can be, for example, set to about 0.005 parts by weight or more, typically 0.01 parts by weight or more is appropriate, preferably 0.05 parts by weight or more, and can be set to 0.10 parts by weight or more, 0.15 parts by weight or more, or 0.20 parts by weight or more. By increasing the content of the photopolymerization initiator, the photocurability of the BP-type hybrid adhesive composition is improved. In addition, the content of the photopolymerization initiator relative to 100 parts by weight of the monomer components constituting the BP-type hybrid adhesive composition is typically set to 5 parts by weight or less, preferably 2 parts by weight or less, and can be set to 1 part by weight or less, 0.7 parts by weight or less, or 0.5 parts by weight or less. From the viewpoint of suppressing gelation of the BP-type hybrid adhesive composition, it is advantageous that the content of the photopolymerization initiator is not excessive.

[0300] In the aforementioned BP-type mixed adhesive composition, known crosslinking agents such as isocyanate-based crosslinking agents, epoxy-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, carbodiimide-based crosslinking agents, melamine-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, hydrazine-based crosslinking agents, and amine-based crosslinking agents can be formulated as needed. Peroxides can also be used as crosslinking agents. These crosslinking agents can be used alone or in combination of two or more. Adhesive layer A formed from the BP-type mixed adhesive composition containing the crosslinking agent preferably contains the crosslinking agent mainly in the form after the crosslinking reaction. By using the crosslinking agent, the cohesive force of adhesive layer A can be appropriately adjusted.

[0301] There is no particular limitation on the amount of crosslinking agent used (or the total amount of two or more crosslinking agents used). From the viewpoint of achieving a well-balanced adhesive with good adhesive properties such as bonding strength and cohesion, it is generally appropriate for the amount of crosslinking agent used to be about 5 parts by weight or less relative to 100 parts by weight of the monomer components constituting the BP-type mixed adhesive composition. This can be 3 parts by weight or less, 1 part by weight or less, 0.50 parts by weight or less, 0.30 parts by weight or less, or 0.20 parts by weight or less. There is no particular limitation on the lower limit of the amount of crosslinking agent used; it is sufficient to be more than 0 parts by weight relative to 100 parts by weight of the monomer components constituting the BP-type mixed adhesive composition. In some embodiments, the amount of crosslinking agent used relative to 100 parts by weight of the monomer components constituting the BP-type mixed adhesive composition can be, for example, 0.001 parts by weight or more, 0.01 parts by weight or more, 0.05 parts by weight or more, or 0.10 parts by weight or more.

[0302] The aforementioned BP-type mixed adhesive composition may contain various chain transfer agents known in the art. As chain transfer agents, thiols such as n-dodecyl mercaptan, tert-dodecyl mercaptan, mercaptoacetic acid, and α-thioglycerol may be used. Alternatively, chain transfer agents without sulfur atoms (non-sulfur chain transfer agents) may be used. Specific examples of non-sulfur chain transfer agents include: anilines such as N,N-dimethylaniline and N,N-diethylaniline; terpenes such as α-pinene and terpinene; styrene such as α-methylstyrene and α-methylstyrene dimer; compounds containing benzylidene groups such as dibenzylidene acetone, cinnamyl alcohol, and cinnamaldehyde; hydroquinones such as hydroquinone and 1,4-dihydroxynaphthalene; quinones such as benzoquinone and naphthoquinone; alkenes such as 2,3-dimethyl-2-butene and 1,5-cyclooctadiene; alcohols such as phenol, benzyl alcohol, and allyl alcohol; benzyl hydrogens such as diphenylbenzene and triphenylbenzene; and so on. Chain transfer agents can be used alone or in combination of two or more. When using a chain transfer agent, the amount used relative to 100 parts by weight of the monomer component can be set to, for example, about 0.01 to 1 part by weight. Alternatively, it is preferable to implement the method without using a chain transfer agent.

[0303] Other components that can be included in a BP-type mixed adhesive composition include silane coupling agents. By using silane coupling agents, the peel strength to the adhered material (e.g., a glass plate) can be improved. Additionally, adhesive layer A can contain a silane coupling agent. Adhesive layer A containing a silane coupling agent can be suitably formed using a BP-type mixed adhesive composition containing a silane coupling agent. One silane coupling agent can be used alone or in combination of two or more.

[0304] The aforementioned BP-type mixed adhesive composition may, as needed, include tackifying resins (e.g., rosin-based, petroleum-based, terpene-based, phenol-based, ketone-based tackifying resins), viscosity modifiers (e.g., tackifiers), leveling agents, antioxidants, plasticizers, fillers, stabilizers, preservatives, anti-aging agents, and other additives conventional in the adhesive field as other arbitrary components. Such additives can be made from conventionally known substances, and detailed descriptions are omitted as they are not specifically intended to characterize this invention.

[0305] It should be noted that the aforementioned BP-type mixed adhesive composition can achieve good adhesive strength without using the aforementioned tackifying resin. Therefore, in some embodiments, the content of the aforementioned tackifying resin in the adhesive layer or adhesive composition may be, for example, less than 10 parts by weight, and further less than 5 parts by weight, relative to 100 parts by weight of the monomer component. The content of the aforementioned tackifying resin may be less than 1 part by weight (e.g., less than 0.5 parts by weight) or less than 0.1 parts by weight (more than 0 parts by weight and less than 0.1 parts by weight). The aforementioned adhesive layer or adhesive composition may also be free of tackifying resin.

[0306] By curing the aforementioned BP-type mixed adhesive composition, an adhesive layer A containing a BP polymer (hereinafter sometimes referred to as "BP-type adhesive layer A") can be formed. The curing of the BP-type mixed adhesive composition is preferably carried out in a manner that reacts the olefinic unsaturated groups contained in the adhesive composition and leaves the benzophenone structure contained in the BP-type mixed adhesive composition intact. The curing can preferably be carried out by irradiation with active energy rays. As the active energy ray used to form adhesive layer A, ultraviolet light is preferred, and more preferably, ultraviolet light containing no components with wavelengths below 300 nm or with minimal components of that wavelength is preferred.

[0307] BP-type adhesive layer A is manufactured using the aforementioned BP-type mixed adhesive composition. This BP-type adhesive layer A may comprise a BP polymer and a polymer derived from an olefinically unsaturated compound. In some preferred embodiments, the aforementioned BP-type mixed adhesive composition may be a composition in which the olefinically unsaturated compound does not contain olefinically unsaturated BP. Based on this composition, a BP-type adhesive layer A comprising a BP polymer and a polymer derived from an olefinically unsaturated compound, wherein the polymer is a non-BP polymer, can be manufactured.

[0308] The method for manufacturing BP type adhesive layer A using a BP type mixed adhesive composition can be carried out by using a BP type mixed adhesive composition instead of the base polymer in the adhesive layer forming step and adhesive layer curing step of the second embodiment described above.

[0309] Regarding the curing conditions in the adhesive layer curing process of this embodiment, in order to react the above-mentioned olefinic unsaturated groups and leave the benzophenone structure, it is preferable to use a light source such as a black light or a UV-LED light that can irradiate ultraviolet light that does not contain components with wavelengths below 300nm or has few components with that wavelength.

[0310] Self-emissive display device

[0311] The self-emissive display device of the second side of the present invention is a display device in which tiny and numerous light-emitting elements are arranged on a wiring substrate, and each light-emitting element selectively emits light through a light-emitting control means connected to it, thereby directly displaying visual information such as text / images / videos on the display screen by flashing the light-emitting elements. Examples of self-emissive display devices include mini / micro LED display devices and organic EL (electroluminescent) display devices. The photocurable adhesive sheet A of the first side of the present invention is particularly suitable for the manufacture of mini / micro LED display devices.

[0312] Figure 4 This is a schematic diagram (cross-sectional view) illustrating one embodiment of the self-emissive display device (mini / micro LED display device) of the second side of the present invention.

[0313] Figure 4 In this embodiment, the mini / micro LED display device 2A comprises the following components: a display panel on one side of a substrate 21 on which a plurality of LED chips 23 are arranged via a metal wiring layer 22; an adhesive layer 20 laminated on the display panel and sealing the metal wiring layer 22 and the plurality of LED chips 23; and a cover member 24 laminated on the upper part (image display side) of the adhesive layer 20. The cover member 24 is not particularly limited and may be made of the same material as the aforementioned "substrate".

[0314] In the mini / micro LED display device 2A of this embodiment, a metal wiring layer 22 for transmitting light emission control signals to each LED chip 23 is stacked on the substrate 21 of the display panel. LED chips 23 emitting red (R), green (G), and blue (B) light are alternately arranged on the substrate 21 of the display panel, separated by the metal wiring layer 22. The metal wiring layer 22 is formed of a metal such as copper, and reflects the light emitted by each LED chip 23, reducing image clarity. Furthermore, the light emitted by the RGB LED chips 23 mixes, reducing contrast.

[0315] In the mini / micro LED display device 2A of this embodiment, each LED chip 23 arranged on the display panel is sealed by an adhesive layer 20. The adhesive layer 20 is composed of a cured product of the adhesive layer A of the present invention. The adhesive layer 20 fully follows the minute height differences between the plurality of LED chips 23, sealing them without gaps.

[0316] The adhesive layer 20 has sufficient light-shielding properties in the visible light region. By using the highly light-shielding adhesive layer 20 to seal the minute height differences between the LED chips 23 without gaps, reflections caused by the metal wiring layer 22 can be prevented, color mixing between the LED chips 23 can be prevented, and contrast can be improved.

[0317] Furthermore, since the adhesive layer 20 is a cured product of the adhesive layer A, it has excellent processability. Therefore, it is possible to prevent insufficient adhesive during the cutting process of the mini / micro LED display device 2A of this embodiment, as well as the overflow and sagging of the adhesive layer 20 from the end during storage.

[0318] The self-emissive display device (mini / micro LED display device) of this embodiment may also include optical components other than the display panel, adhesive layer, and cover member. There are no particular limitations on the optical components mentioned above; examples include polarizing plates, retardation plates, anti-reflective films, viewing angle adjustment films, and optical compensation films. It should be noted that the optical components also include components that maintain the legibility of the display device and input device and serve decorative and protective functions (such as outer films, decorative films, and surface protection plates).

[0319] The self-emissive display device (mini / micro LED display device) of this embodiment is not particularly limited, but it is preferably manufactured by a method including the following steps.

[0320] (1) A process of laminating a photocurable adhesive layer A to a display panel on which multiple light-emitting elements are arranged on one side of a substrate, and sealing the aforementioned light-emitting elements using the adhesive layer A.

[0321] (2) The process of curing the aforementioned adhesive layer by irradiating it with radiation.

[0322] Figure 5 This diagram illustrates the steps of one embodiment of a method for manufacturing a self-emissive display device (mini / micro LED display device) for implementing the second side of the present invention. In this embodiment, as... Figure 5 As shown in (a), a display panel is constructed using a photocurable adhesive sheet 1E on the second side of the present invention and a plurality of light-emitting elements (LED chips) 23 arranged on one side of a substrate 21 across a metal wiring layer 22.

[0323] In this embodiment, the photocurable adhesive sheet 1E is composed of an adhesive layer 10 manufactured by the manufacturing method of the photocurable adhesive sheet A according to the second embodiment of the present invention and a covering member 24. The adhesive layer 10 has a composition in which a crosslinking agent 11 and a photopolymerization initiator 12 are dissolved in a base polymer. In this embodiment, the method in which only one of the crosslinking agent 11 and the photopolymerization initiator 12 is dissolved in the adhesive layer 10 is also included. In this embodiment, from the main surface 10A in contact with the support S3, there is a concentration gradient of crosslinking agent 11 and photopolymerization initiator 12 in the thickness direction.

[0324] In this embodiment, the photocurable adhesive sheet 1E has a covering member 24, but it may also be without a covering member 24. The covering member 24 is not particularly limited and may be made of the same material as the "substrate" described above, or it may be a release film (release film).

[0325] Next, as Figure 5 As shown in (b), the main surface 10B of the uncovered member 24 is not laminated in the adhesive layer 10 of the photocurable adhesive sheet 1E on the surface of the display panel where multiple LED chips are arranged, and the LED chips 23 and the metal wiring layer 22 are sealed by the adhesive layer 10. This lamination can be performed by known methods, for example, under heating and pressurization conditions using an autoclave. The adhesive layer 10 of the photocurable adhesive sheet 1E has high fluidity and exhibits excellent height difference absorption. Therefore, the adhesive layer 10 seals the surface in such a way that the height difference between the metal wiring layer 22 and the multiple LED chips 23 is filled without gaps.

[0326] Next, as Figure 5 As shown in (c), the adhesive layer 10 is cured by irradiation. Upon irradiation, the photopolymerization initiator 12 decomposes and generates free radicals or ions, initiating a polymerization / crosslinking reaction of the crosslinking agent 12. The radiation source is not particularly limited as long as the adhesive layer 10 cures; ultraviolet light, which allows the adhesive layer 10 to transmit light, is preferred. That is, the adhesive layer 10 has high light-blocking properties to visible light and high transmittance to ultraviolet light, thus enabling curing of the adhesive layer 10 by ultraviolet light. Figure 5 (c) is an embodiment in which the adhesive layer 10 is cured by irradiating it with ultraviolet light U.

[0327] The preferred ultraviolet light source is ultraviolet light with a wavelength of 200 to 400 nm, more preferably ultraviolet light with a wavelength of 330 to 400 nm. Furthermore, if the adhesive layer 10 is composed of a BP-type adhesive layer A, it can be cured by irradiating it with ultraviolet light containing wavelengths capable of exciting the benzophenone structure. Specifically, a light source capable of irradiating ultraviolet light containing wavelengths below 300 nm is preferred.

[0328] As a light source for ultraviolet irradiation, high-pressure mercury lamps, low-pressure mercury lamps, microwave excitation lamps, metal halide lamps, chemical lamps, black light lamps, or LEDs can be used. Furthermore, the irradiation time and method can be appropriately set as long as the adhesive layer 10 is cured without adversely affecting the display panel, and the cured adhesive layer 10 exhibits sufficient processability. For example, the ultraviolet irradiation dose (cumulative light intensity) is preferably 1000 mJ / cm². 2 ~10000mJ / cm 2 More preferably 2000 mJ / cm 2 ~4000mJ / cm 2 A further preferred value is 3000 mJ / cm². 2 .

[0329] By curing the adhesive layer 10, such as Figure 5 As shown in (d), a self-emissive display device (mini / micro LED display device) 2B can be obtained. Figure 5 In (d), the adhesive layer 20 is an adhesive layer formed by curing the adhesive layer 10. The self-emissive display device (mini / micro LED display device) 2B is an embodiment of an example of a self-emissive display device (mini / micro LED display device) showing the second side of the present invention.

[0330] By curing the adhesive layer 10, the crosslinking agent 11 undergoes crosslinking / polymerization to form a crosslinked structure 11', thus forming the adhesive layer 20. The processability of the adhesive layer 20 is improved, suppressing insufficient adhesive during cutting, overflow of the adhesive layer from the ends during storage, and sagging. In addition, the adhesive layer 20 can suppress the generation of gases such as carbon dioxide caused by heating of the display panel, prevent the formation of bubbles, and improve the bonding reliability.

[0331] in addition, Figure 5 In embodiment (d), the crosslinking density is higher on the side of the adhesive layer 20 that contacts the support S3 than on the opposite side. This configuration is preferred, for example, from the perspective of improving flexibility when using a self-emissive display device (mini / micro LED display device) as a flexible image display device that bends outward.

[0332] That is, when a flexible display is bent, tensile stress is typically applied to the outer side and compressive stress to the inner side, with the stress on the outer side being stronger than that on the inner side. Therefore, by positioning the upper part (image display side) of the adhesive layer 20 on the outer side when the flexible display is bent, the durability against bending can be improved.

[0333] Example

[0334] The present invention will be described in more detail below based on embodiments, but the present invention is not limited to these embodiments.

[0335] [Example 1]

[0336] (Preparation of prepolymer)

[0337] In a detachable flask equipped with a thermometer, stirrer, reflux condenser, and nitrogen inlet, 67 parts by weight of butyl acrylate (BA), 14 parts by weight of cyclohexyl acrylate (CHA), 19 parts by weight of 4-hydroxybutyl acrylate (4-HBA), 0.09 parts by weight of photopolymerization initiator (BASF, trade name "Irgacure 184"), and 0.09 parts by weight of photopolymerization initiator (BASF, trade name "Irgacure 651") were added as monomer components. Nitrogen gas was then introduced, and nitrogen purging was carried out for approximately 1 hour with stirring. Then, at 5 mW / cm²... 2 Polymerization was carried out by irradiation with UVA, and the reaction rate was adjusted to 5-15% to obtain acrylic prepolymer solution A.

[0338] (Preparation of the adhesive composition)

[0339] To the acrylic prepolymer solution A obtained above (the total amount of prepolymer is set to 100 parts by weight), 9 parts by weight of 2-hydroxyethyl acrylate (HEA), 8 parts by weight of 4-hydroxybutyl acrylate (4-HBA), 0.02 parts by weight of dipentaerythritol hexaacrylate (manufactured by Shin-Nakamura Kogyo Chemical Co., Ltd., trade name "KAYARAD DPHA") as a multifunctional monomer, 0.35 parts by weight of silane coupling agent (3-epoxypropoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403") and 0.45 parts by weight of photopolymerization initiator (manufactured by BASF, "Irgacure 651") were added to obtain adhesive composition B.

[0340] (Preparation of the black adhesive composition)

[0341] Add 5.8 parts by weight of a 20% dispersion of black pigment (TOKUSHIKI "9256BLACK") and 0.2 parts by weight of additional photopolymerization initiator (BASF "Irgacure 651") to 100 parts by weight of the above adhesive composition B to obtain black adhesive composition C.

[0342] (Making the adhesive sheet)

[0343] The aforementioned black adhesive composition C is applied to the release surface of a 38 μm thick release film R1 (manufactured by Mitsubishi Resin Co., Ltd., trade name "MRF#38"), where one side of the polyester film is the release surface. This release film R2 (manufactured by Mitsubishi Resin Co., Ltd., MRE#38), where one side of the polyester film is the release surface, is then covered to block air. From one side of this laminate, a black light (manufactured by Toshiba Corporation, trade name FL15BL) is used with an illuminance of 5 mW / cm². 2 Cumulative light intensity 1300 mJ / cm 2 The conditions are irradiated with ultraviolet light. As a result, an adhesive sheet D with an adhesive layer of about 50 μm thickness, which is the cured product of the above-mentioned black adhesive composition C, is obtained in the form of a substrate-free double-sided adhesive sheet, which is sandwiched between the above-mentioned release films R1 and R2.

[0344] It should be noted that the illuminance values ​​of the black light lamps mentioned above are based on measurements taken by an industrial UV testing device (manufactured by TOPCON Corporation, trade name: UVR-T1, light-receiving part model UD-T36) with a peak sensitivity wavelength of approximately 350nm.

[0345] (Fabrication of UV-curable adhesive sheets)

[0346] The release film R2 of the adhesive sheet D was peeled off, and a solution obtained by dissolving a photopolymerization initiator (BASF, trade name "Irgacure 651") in trimethylolpropane triacrylate (TMPTA) at a concentration of 5% by weight was applied using a wire-wound rod coater (RD Specialties). The target wet coating thickness was 15 μm. After coating, the sheet was heated in an oven at 110°C for 2 minutes. Then, the adhesive surface was protected again with the release film R2, resulting in a photocurable adhesive sheet E containing an adhesive layer containing dissolved TMPTA and the photopolymerization initiator, as a substrate-free double-sided adhesive sheet.

[0347] [Example 2]

[0348] (Preparation of solvent-based black adhesive composition)

[0349] In a detachable flask equipped with a thermometer, stirrer, reflux condenser, and nitrogen inlet, 60 parts by weight of n-butyl acrylate (BA), 6 parts by weight of cyclohexyl acrylate (CHA), 18 parts by weight of N-vinyl-2-pyrrolidone (NVP), 1 part by weight of isostearate acrylate (iSTA), 15 parts by weight of 4-hydroxybutyl acrylate (4HBA), 0.125 parts by weight of α-thioglycerol as a chain transfer agent, and 122 parts by weight of ethyl acetate as a polymerization solvent were added. 0.2 parts by weight of 2,2'-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator were also added. Solution polymerization was carried out under a nitrogen atmosphere to obtain a solution containing an acrylic polymer with a Mw of approximately 500,000.

[0350] In the solution obtained above, relative to 100 parts of the monomer components used in the preparation of the solution, 0.22 parts by weight of polymerization initiator (manufactured by BASF, "Irgacure 651"), 0.27 parts by weight of isocyanate-based crosslinking agent (trimethylolpropane / phenylene diisocyanate adduct, manufactured by Mitsui Chemicals Co., Ltd., trade name "TAKENATE D-110N", solids concentration 75%), and dipentaerythritol hexaacrylate (manufactured by Shin-Nakamura Kogyo Chemical, trade name "KAYARAD") were added. The solvent-based black adhesive composition was obtained by mixing 2.2 parts by weight of DPHA, 1 part by weight of polypropylene glycol #400 diacrylate (manufactured by Shin-Nakamura Kogyo Chemical), 0.33 parts by weight of silane coupling agent (3-epoxypropoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Industry Co., Ltd., trade name "KBM-403"), 0.3 parts by weight of antioxidant (manufactured by BASF, trade name "IRGANOX1135"), 0.18 parts by weight of polyether polyol (manufactured by ADEKA, trade name "ADEKA Polyether EPD-300"), and 4 parts by weight of a 20% dispersion of black pigment (manufactured by TOKUSHIKI, "9170BLACK").

[0351] (Fabrication of UV-curable adhesive sheets)

[0352] Two 38 μm thick release films (Mitsubishi Resin Co., Ltd., MRF#38) of polyester film were prepared, with one side serving as the release surface. The solvent-based black adhesive composition prepared above was coated onto the release surface of the first release film, dried at 60°C for 3 minutes, and then dried at 120°C for 3 minutes to form a 134 μm thick photocurable adhesive layer. The release surface of the second release film was then bonded onto this adhesive layer for protection, resulting in a substrate-free double-sided adhesive sheet.

[0353] [Example 3]

[0354] (Preparation of the adhesive composition)

[0355] An acrylic copolymer (manufactured by BASF, trade name "acResin A260UV", Tg: -39℃, Mw: 19×10⁻⁶) with benzophenone side chains was added to a detachable flask equipped with a thermometer, stirrer, reflux condenser, and nitrogen inlet. 4 An adhesive composition was prepared by mixing 50 parts by weight of BP equivalent (2 mg / g), 26 parts by weight of butyl acrylate (BA), 8 parts by weight of N-vinyl-2-pyrrolidone (NVP), 16 parts by weight of isobornyl acrylate (IBXA), and 0.2 parts by weight of photopolymerization initiator (manufactured by BASF, trade name "Irgacure 184").

[0356] (Preparation of the black adhesive composition)

[0357] To prepare a black adhesive composition, 2 parts by weight of a 20% dispersion of black pigment (TOKUSHIKI "9256BLACK") were added to 100 parts by weight of the above adhesive composition.

[0358] (Fabrication of UV-curable adhesive sheets)

[0359] The aforementioned black adhesive composition was applied to the release side of a 38 μm thick release film R1 (manufactured by Mitsubishi Resin Corporation, trade name "MRF#38"), which has one side as the release side of the polyester film. This release film R2 (manufactured by Mitsubishi Resin Corporation, trade name "MRE#38"), which has one side as the release side of the polyester film, was then covered to block air. From one side of this laminate, a black light (manufactured by Toshiba Corporation, trade name FL15BL) was used with an illuminance of 5 mW / cm². 2 Cumulative light intensity 1300 mJ / cm 2 The conditions are irradiated with ultraviolet light. Thus, a photocurable adhesive sheet with an adhesive layer of about 104 μm thickness, which is a cured product of the above-mentioned black adhesive composition, is obtained in the form of a substrate-free double-sided adhesive sheet, which is sandwiched between the above-mentioned release films R1 and R2.

[0360] [Example 4]

[0361] (Preparation of the black adhesive composition)

[0362] To 100 parts by weight of the adhesive composition B prepared in Example 1, 4 parts by weight of a 20% dispersion of black pigment (TOKUSHIKI "9256BLACK"), 0.2 parts by weight of an additional photopolymerization initiator (BASF "Irgacure 651"), and 1 part by weight of 4-acryloyloxybenzophenone (Ark Pharm) were added to obtain a black adhesive composition.

[0363] (Fabrication of UV-curable adhesive sheets)

[0364] The aforementioned black adhesive composition was applied to the release side of a 38 μm thick release film R1 (manufactured by Mitsubishi Resin Corporation, trade name "MRF#38"), which has one side as the release side of the polyester film. This release film R2 (manufactured by Mitsubishi Resin Corporation, trade name "MRE#38"), which has one side as the release side of the polyester film, was then covered to block air. From one side of this laminate, a black light (manufactured by Toshiba Corporation, trade name FL15BL) was used with an illuminance of 5 mW / cm². 2 Cumulative light intensity 1300 mJ / cm 2 The material is irradiated with ultraviolet light. As a result, an adhesive sheet with an adhesive layer of about 100 μm thickness, which is a cured product of the above-mentioned black adhesive composition, is obtained in the form of a substrate-free double-sided adhesive sheet, which is sandwiched between the above-mentioned release films R1 and R2.

[0365] It should be noted that the illuminance values ​​of the black light lamps mentioned above are based on measurements taken by an industrial UV testing device (manufactured by TOPCON Corporation, trade name: UVR-T1, light-receiving part model UD-T36) with a peak sensitivity wavelength of approximately 350nm.

[0366] [Example 5]

[0367] Two parts of 4-acryloyloxybenzophenone were used, and otherwise, a light-curable adhesive sheet was prepared in the same manner as in Example 4.

[0368] [Reference Example 1]

[0369] (Preparation of the adhesive composition)

[0370] To the acrylic prepolymer solution A obtained in Example 1 (with the total amount of prepolymer set to 100 parts by weight), 9 parts by weight of 2-hydroxyethyl acrylate (HEA), 8 parts by weight of 4-hydroxybutyl acrylate (4-HBA), 0.45 parts by weight of polymerization initiator (manufactured by BASF, "Irgacure 651"), and 1 part by weight of nano silica (manufactured by Japan Aerosil Co., Ltd., trade name "R976S") were added to obtain an adhesive composition.

[0371] (Preparation of the black adhesive composition)

[0372] Add 5.8 parts by weight of a 20% dispersion of black pigment (TOKUSHIKI "9256BLACK") and 0.2 parts by weight of additional photopolymerization initiator (BASF "Irgacure 651") to 100 parts by weight of the above adhesive composition to obtain a black adhesive composition.

[0373] (Making the adhesive sheet)

[0374] The aforementioned black adhesive composition was applied to the release surface of a 38 μm thick release film R1 (manufactured by Mitsubishi Resin Co., Ltd., trade name "MRF#38"), with one side of the polyester film serving as the release surface. This was followed by covering the release film R2 (manufactured by Mitsubishi Resin Co., Ltd., MRE#38), with the other side of the polyester film also serving as the release surface, thus blocking air. From one side of this laminate, a black light (manufactured by Toshiba Corporation, trade name FL15BL) was used with an illuminance of 5 mW / cm². 2 Cumulative light intensity 1300 mJ / cm 2 The material is irradiated with ultraviolet light. Thus, an adhesive sheet with an adhesive layer approximately 100 μm thick, which is a cured product of the aforementioned black adhesive composition, is obtained as a substrate-free double-sided adhesive sheet, sandwiched between the aforementioned release films R1 and R2. It should be noted that the resulting adhesive sheet does not exhibit photocurability.

[0375] [Reference Example 2]

[0376] The amount of nano-silica used was set to 3 parts by weight, and otherwise, an adhesive sheet was obtained in the same manner as in Reference Example 1.

[0377] [Reference Example 3]

[0378] The amount of nano-silica used was set to 5 parts by weight, and otherwise, an adhesive sheet was obtained in the same manner as in Reference Example 1.

[0379] [Reference Example 4]

[0380] The amount of nano-silica used was set to 7 parts by weight, and otherwise, an adhesive sheet was obtained in the same manner as in Reference Example 1.

[0381] It should be noted that the purpose of Reference Examples 1 to 4 is to verify the energy storage modulus and its ratio that take into account both height difference tracking and processability, using an adhesive sheet that does not exhibit photocurability, and to evaluate the energy storage modulus by changing the amount of nano-silica used.

[0382] [Comparative Example 1]

[0383] (Making the adhesive sheet)

[0384] The adhesive composition B prepared in Example 1 was coated onto the release side of a 38 μm thick release film R1 (manufactured by Mitsubishi Resin Co., Ltd., trade name "MRF#38"), which has one side of the polyester film as the release side, and then covered with the release film R2 (manufactured by Mitsubishi Resin Co., Ltd., MRE#38), which has one side of the polyester film as the release side, thus blocking out air. From one side of this laminate, a black light lamp (manufactured by Toshiba Corporation, trade name FL15BL) was used with an illuminance of 5 mW / cm². 2 Cumulative light intensity 1300 mJ / cm 2The adhesive layer, approximately 50 μm thick, is obtained as a cured product of the adhesive composition B described above, under ultraviolet light irradiation. This results in an adhesive sheet sandwiched between the release films R1 and R2, forming a substrate-free double-sided adhesive sheet.

[0385] (Fabrication of UV-curable adhesive sheets)

[0386] The release film R2 of the adhesive sheet was peeled off, and a solution obtained by dissolving a photopolymerization initiator (BASF, trade name "Irgacure 651") in trimethylolpropane triacrylate (TMPTA) at a concentration of 5% by weight was applied using a wire-wound rod coater (RD Specialties, #7) to achieve a wet coating thickness of 15 μm. After coating, the sheet was heated in an oven at 110°C for 2 minutes. Then, the adhesive surface was protected again with the release film R2, resulting in a photocurable adhesive sheet containing an adhesive layer containing dissolved TMPTA and the photopolymerization initiator, as a substrate-free double-sided adhesive sheet.

[0387] [Comparative Example 2]

[0388] The adhesive sheet D obtained in Example 1 was used as the adhesive sheet in Comparative Example 2. It should be noted that adhesive sheet D does not exhibit photocurability.

[0389] (evaluate)

[0390] The adhesive sheets obtained using the above-described embodiments, reference examples, and comparative examples were evaluated as follows. The evaluation methods are shown below. The results are shown in Table 1.

[0391] [Evaluation of Transmission Rate]

[0392] Peel off the release film from one side of the adhesive sheet and bond alkali-free glass to the exposed side. Then, peel off the release film from the other side of the adhesive sheet to obtain a sample with the adhesive sheet bonded to the alkali-free glass plate.

[0393] The total transmittance was measured using a haze meter (manufactured by Murakami Color Science Research Institute Co., Ltd., trade name "HN-150") according to the method specified in JIS K7361.

[0394] [Evaluation of Energy Storage Modulus]

[0395] The evaluation was conducted using TA Instruments' ARES GII.

[0396] The adhesive sheets, which are stacked to a thickness of about 1 mm, are clamped with an 8 mm parallel plate. The storage modulus G' at 10 °C, 25 °C and 85 °C is read when the initial strain is 1%, the frequency is 1 Hz and the heating rate is 5 °C / min from -50 °C to 100 °C. This value is taken as the storage modulus G' before curing (G'b10, G'b25, G'b85).

[0397] Regarding the solidified energy storage modulus G', it will be based on a cumulative light intensity of 3000 mJ / cm². 2 The adhesive sheet, which is held in a peeled film state, is irradiated with a high-pressure mercury lamp to obtain a sheet layer with a thickness of about 1 mm. The same method is used to evaluate it as the storage modulus G' (G'a10, G'a25, G'a85) after curing.

[0398] This cumulative light intensity is based on the measurement value of an industrial UV testing device (manufactured by TOPCON, trade name: UVR-T1, light-receiving part model UD-T36) with a peak sensitivity wavelength of approximately 350nm.

[0399] It should be noted that the adhesive sheets of Reference Examples 1 to 4 and Comparative Example 2 do not exhibit photocurability, therefore the storage modulus G' after curing was not evaluated.

[0400] [Evaluation of height difference following performance]

[0401] (Making an object with textured surfaces)

[0402] After laminating a TAC film (60 μm thick) and an adhesive (20 μm thick) onto a 45 mm × 50 mm glass plate, a CO2 laser (wavelength 10.6 μm / laser diameter 0 μm) was used to perform linear etching on the central 10 mm × 10 mm area with a vertical spacing of 150 μm and a horizontal spacing of 225 μm. This resulted in an adherend A with the TAC film and adhesive layer processed into a grid-like uneven shape.

[0403] This adhesive A mimics an LED panel with multiple LED films arranged on a substrate.

[0404] (Making the adhesive sheet)

[0405] The adhesive sheets prepared in Examples 1 and 3, Reference Examples 1-4, and Comparative Examples 1 and 2 were stacked to a thickness of approximately 200 μm. The adhesive sheet prepared in Example 2 was stacked to a thickness of approximately 250 μm. The release film on one side of these stacked adhesive sheets was peeled off, and a PET film with a thickness of 75 μm was laminated onto the exposed side.

[0406] (Vacuum bonding)

[0407] Using a vacuum laminating apparatus (CRIMB Products, SE340aaH), the adhesive surface exposed by peeling off the release film from the other side of the laminated adhesive sheet obtained above is bonded to the processed surface of the substrate A with a precision within the processing range where the adhesive sheet can completely cover the substrate A, thus obtaining evaluation samples formed of PET film / laminated adhesive sheet / substrate A. These samples are then subjected to autoclaving (50°C / 0.5MPa for 60 minutes) to ensure a tight seal.

[0408] (Evaluation of height difference following performance)

[0409] In the aforementioned evaluation samples, the properties of the processed part of the adhered object A being identified as transparent and the un-trackable part as white were evaluated by taking pictures with a fixed-point camera to calculate the area of ​​the white part and the height difference tracking performance.

[0410] Height difference following accuracy (%) = 100 - {[Area of ​​white part at evaluation time] / [Area of ​​white part before bonding = 1cm²]} 2 ]×100}

[0411] [Processability Evaluation]

[0412] (Preparation of laminated products for processability evaluation)

[0413] The release film of the laminated adhesive sheet prepared for the height difference tracking evaluation was peeled off and bonded to a MISUMI Corporation fr-4 substrate (1.2 mm thick). After autoclaving (50°C / 0.5 MPa for 15 minutes), the photocurable products of Examples 1-3 and Comparative Example 1 were irradiated with ultraviolet light. The ultraviolet irradiation conditions were set to a high-pressure mercury lamp and a cumulative light dose of 3000 mJ / cm. 2 It should be noted that this cumulative light intensity is based on the measurement value of an industrial UV testing device (manufactured by TOPCON, trade name: UVR-T1, light-receiving part model UD-T36) with a peak sensitivity wavelength of approximately 350nm.

[0414] (Processing)

[0415] The machinability evaluation obtained above was obtained by cutting the laminated product using a Disco DTF6450. The cutting conditions were set as follows: blade type P1A861 (abrasive #400), probe 30krpm, speed 30mm / s, and cooling water 1L / min.

[0416] (Process-oriented evaluation)

[0417] The cut ends were observed from the side of the laminated adhesive sheet using a stereomicroscope, and processability was evaluated by the amount of adhesive overflow from the cut ends. The evaluation criteria were set as follows.

[0418] ○: 0~150μm

[0419] △: 150~200μm

[0420] ×: Above 200μm

[0421] [Evaluation of reflectivity]

[0422] A board was fabricated by laminating aluminum foil onto a black acrylic sheet. The release film on one side of the adhesive sheets prepared in Examples 1-3 and Comparative Examples 1 and 2 was peeled off, and a 75 μm thick PET film was adhered to the exposed side. The release film on the other side was peeled off, and the exposed adhesive side was laminated onto the aluminum foil side of the aforementioned board, forming a sample. For the obtained sample, the reflectance (%) of the visible light region with regular reflection at 5° was measured using a spectrophotometer U4100 (manufactured by Hitachi High-Technologies Corporation) with the PET film set as the light source side.

[0423] [Table 1]

[0424]

[0425] Examples 1-5, which are photocurable adhesive sheets, exhibit excellent height difference following (height difference absorption) and processability. As shown in Reference Examples 1-4 and Comparative Example 2, height difference following (height difference absorption) is improved when the storage modulus at 85°C before curing is less than 65 kPa. Furthermore, as shown in Reference Examples 1-4, excellent height difference following (height difference absorption) and processability are exhibited in regions where the storage modulus (G'b85) at 85°C before curing is less than 65 kPa, and the ratio (G'a10 / G'b85) of the storage modulus (G'a10) at 10°C after curing to the storage modulus (G'b85) at 85°C before curing is greater than 3.3. It should be noted that the adhesive sheets in Examples 1 to 4 do not exhibit photocurability, so the evaluation was performed using the ratio (G'b10 / G'b85) of the storage modulus at 10°C before curing to the storage modulus at 85°C before curing.

[0426] Comparative Example 1, which belongs to the category of photocurable adhesive sheets, shows excellent height difference tracking (height difference absorption) and processability, but has high reflectivity because it does not contain black pigment.

[0427] The following are notes on variations of the present invention.

[0428] [Note 1] A photocurable adhesive sheet comprising an adhesive layer that cures upon exposure to radiation.

[0429] The aforementioned adhesive layer contains a colorant.

[0430] The maximum transmittance of the aforementioned adhesive layer at wavelengths of 200–400 nm is greater than the maximum transmittance at wavelengths of 400–700 nm.

[0431] The storage modulus (G'b85) of the aforementioned adhesive layer before curing at 85°C is less than 65 kPa.

[0432] The storage modulus (G'a10) of the cured adhesive layer at 10°C and the storage modulus (G'b85) of the uncured adhesive layer at 85°C satisfy the following relationship (1).

[0433] 3.3 <G'a10 / G'b85 (1)

[0434] [Note 2] According to the photocurable adhesive sheet described in Note 1, the aforementioned colorant is a colorant whose maximum transmittance at wavelengths of 200–400 nm is greater than the maximum transmittance at wavelengths of 400–700 nm.

[0435] [Note 3] The photocurable adhesive sheet according to Note 1 or 2, wherein the curing based on the aforementioned radiation irradiation is based on a cumulative light intensity of 3000 mJ / cm². 2 Curing by ultraviolet radiation.

[0436] [Note 4] The photocurable adhesive sheet according to any one of Notes 1 to 3, wherein the cured adhesive layer has a storage modulus (G'a10) of 90 kPa or more at 10°C.

[0437] [Note 5] The photocurable adhesive sheet according to any one of Notes 1 to 4, wherein the aforementioned adhesive layer contains a base polymer, a crosslinking agent and a photopolymerization initiator.

[0438] [Note 6] The photocurable adhesive sheet according to Note 5, wherein the aforementioned base polymer contains an acrylic polymer.

[0439] [Note 7] The photocurable adhesive sheet according to Note 5 or 6, wherein the aforementioned crosslinking agent contains a polyfunctional (meth)acrylate.

[0440] [Appendix 8] The photocurable adhesive sheet according to any one of Appendices 5 to 7, wherein the aforementioned adhesive layer is a single layer formed from the aforementioned base polymer and having two opposing main surfaces.

[0441] When the aforementioned single-layer adhesive layer is divided into two equal parts along the thickness direction,

[0442] The concentration of the aforementioned crosslinking agent and / or the aforementioned photopolymerization initiator in one of the two main surfaces, namely the region to which the first main surface belongs, is different from the concentration of the aforementioned crosslinking agent and / or the aforementioned photopolymerization initiator in the region to which the other main surface, namely the region to which the second main surface belongs, is different.

[0443] [Note 9] According to Note 8, the photocurable adhesive sheet has a concentration gradient of the aforementioned crosslinking agent and / or the aforementioned photopolymerization initiator in the thickness direction.

[0444] [Appendix 10] A method for manufacturing the photocurable adhesive sheet described in Appendix 8 or 9, characterized in that it comprises the following steps:

[0445] An adhesive layer is formed from the aforementioned base polymer,

[0446] Allow the aforementioned adhesive layer to cure.

[0447] Prepare a solution of the aforementioned crosslinking agent and / or the aforementioned photopolymerization initiator.

[0448] The aforementioned solution is applied to one side of the cured adhesive layer, allowing the aforementioned crosslinking agent and / or the aforementioned photopolymerization initiator contained in the solution to penetrate from the aforementioned one side of the adhesive layer along the thickness direction.

[0449] Allow the aforementioned adhesive layer to dry.

[0450] [Note 11] The photocurable adhesive sheet according to any one of Notes 1 to 4, wherein the aforementioned adhesive layer contains a polymer having a benzophenone structure in the side chain.

[0451] [Note 12] According to Note 11, the photocurable adhesive sheet is wherein the aforementioned adhesive layer is a cured product of an adhesive composition containing an olefinic unsaturated compound and a polymer having a benzophenone structure in the side chain.

[0452] [Appendix 13] A self-emissive display device comprising:

[0453] A display panel in which multiple light-emitting elements are arranged on one side of a substrate, and

[0454] The photocurable adhesive sheet described in any one of Appendices 1 to 9, 11, and 12,

[0455] The light-emitting elements of the aforementioned display panel are sealed by the adhesive layer of the aforementioned photocurable adhesive sheet.

[0456] The aforementioned adhesive layer is cured.

[0457] [Note 14] According to the self-emissive display device described in Note 13, the aforementioned display panel is an LED panel in which a plurality of LED chips are arranged on one side of a substrate.

[0458] [Note 15] A method for manufacturing the self-emissive display device described in Note 13 or 14 includes the following steps:

[0459] A process of sealing the light-emitting elements by means of an adhesive layer of a photocurable adhesive sheet as described in any one of 1 to 9, 11 and 12, on a display panel having a plurality of light-emitting elements arranged on one side of a substrate; and

[0460] The process of curing the aforementioned adhesive layer by irradiating it with radiation.

[0461] [Note 16] In the manufacturing method described in Note 15, the aforementioned radiation is ultraviolet light.

[0462] Industrial availability

[0463] The photocurable adhesive sheet of the present invention is suitable for sealing the light-emitting elements of self-emissive display devices such as mini / micro LEDs.

[0464] Explanation of reference numerals in the attached figures

[0465] 1A~1E Light-curable adhesive sheets

[0466] 10 Adhesive Layer

[0467] 10a~10c Adhesive layer

[0468] 11 Crosslinking agent

[0469] 12 Photopolymerization Initiators

[0470] 13 Solvents

[0471] 14 solutions

[0472] 2A, 2B Self-emissive display devices (mini / micro LED display devices)

[0473] 20 Adhesive layers

[0474] 21 substrate

[0475] 22 Metal wiring layers

[0476] 23. Light-emitting element (LED chip)

[0477] 24 Covering components

[0478] S1 and S2 Supports (peeling film)

Claims

1. A photocurable adhesive sheet comprising an adhesive layer that cures upon exposure to radiation. The adhesive layer contains a base polymer, a crosslinking agent, and a photopolymerization initiator, wherein the crosslinking agent contains a polyfunctional (meth)acrylate. The adhesive layer contains a colorant. The colorant is one whose maximum transmittance at wavelengths of 200-400 nm is greater than the maximum transmittance at wavelengths of 400-700 nm. The maximum transmittance of the adhesive layer at wavelengths of 200-400 nm is greater than the maximum transmittance at wavelengths of 400-700 nm. The storage modulus (G'b85) of the adhesive layer before curing is less than 65 kPa at 85°C. The storage modulus (G'a10) of the cured adhesive layer at 10°C and the storage modulus (G'b85) of the uncured adhesive layer at 85°C satisfy the following relationship (1). 3.3 <G'a10 / G'b85 (1)。 2. The photocurable adhesive sheet according to claim 1, wherein, Curing based on the aforementioned radiation irradiation is based on a cumulative light intensity of 3000 mJ / cm. 2 Curing by ultraviolet radiation.

3. The photocurable adhesive sheet according to claim 1 or 2, wherein, The cured adhesive layer has a storage modulus (G'a10) of 90 kPa or more at 10°C.

4. The photocurable adhesive sheet according to claim 1 or 2, wherein, The base polymer contains an acrylic polymer.

5. A photocurable adhesive sheet comprising an adhesive layer that cures upon exposure to radiation. The adhesive layer contains a colorant. The maximum transmittance of the adhesive layer at wavelengths of 200-400 nm is greater than the maximum transmittance at wavelengths of 400-700 nm. The storage modulus (G'b85) of the adhesive layer before curing is less than 65 kPa at 85°C. The storage modulus (G'a10) of the cured adhesive layer at 10°C and the storage modulus (G'b85) of the uncured adhesive layer at 85°C satisfy the following relationship (1). 3.3 <G'a10 / G'b85 (1), The adhesive layer is a single layer formed from a base polymer, having two opposing main surfaces. When the single-layer adhesive layer is divided into two equal parts along the thickness direction, The concentration of crosslinking agent and / or photopolymerization initiator in the region of one of the two main surfaces, namely the first main surface, is different from the concentration of crosslinking agent and / or photopolymerization initiator in the region of the other, namely the second main surface.

6. The photocurable adhesive sheet according to claim 5, wherein, The single-layer adhesive layer has a concentration gradient of the crosslinking agent and / or the photopolymerization initiator in the thickness direction.

7. A method for manufacturing a photocurable adhesive sheet as described in claim 5 or 6, characterized in that, It includes the following processes: An adhesive layer is formed from the base polymer, Allow the adhesive layer to cure. Prepare a solution of the crosslinking agent and / or the photopolymerization initiator. The solution is applied to one side of the cured adhesive layer, allowing the crosslinking agent and / or the photopolymerization initiator contained in the solution to penetrate from that one side of the adhesive layer along the thickness direction. Allow the adhesive layer to dry.

8. A photocurable adhesive sheet comprising an adhesive layer that cures upon exposure to radiation. The adhesive layer contains a colorant. The maximum transmittance of the adhesive layer at wavelengths of 200-400 nm is greater than the maximum transmittance at wavelengths of 400-700 nm. The storage modulus (G'b85) of the adhesive layer before curing is less than 65 kPa at 85°C. The storage modulus (G'a10) of the cured adhesive layer at 10°C and the storage modulus (G'b85) of the uncured adhesive layer at 85°C satisfy the following relationship (1). 3.3 <G'a10 / G'b85 (1), The adhesive layer contains a polymer having a benzophenone structure in its side chain.

9. The photocurable adhesive sheet according to claim 8, wherein, The adhesive layer is a cured product of an adhesive composition containing an olefinic unsaturated compound and a polymer having a benzophenone structure in its side chain.

10. A self-emissive display device, comprising: A display panel in which multiple light-emitting elements are arranged on one side of a substrate, and Photocurable adhesive film, The photocurable adhesive sheet comprises an adhesive layer that is cured by radiation. The adhesive layer contains a colorant. The maximum transmittance of the adhesive layer at wavelengths of 200-400 nm is greater than the maximum transmittance at wavelengths of 400-700 nm. The storage modulus (G'b85) of the adhesive layer before curing is less than 65 kPa at 85°C. The storage modulus (G'a10) of the cured adhesive layer at 10°C and the storage modulus (G'b85) of the uncured adhesive layer at 85°C satisfy the following relationship (1). 3.3 <G'a10 / G'b85 (1), The light-emitting elements of the display panel are sealed by the adhesive layer of the photocurable adhesive sheet. The adhesive layer is cured.

11. The self-emissive display device according to claim 10, wherein, The display panel is an LED panel with multiple LED chips arranged on one side of a substrate.

12. A method for manufacturing a self-emissive display device according to claim 10 or 11, comprising the following steps: A process of laminating an adhesive layer of the photocurable adhesive sheet according to any one of claims 1 to 6, 8 and 9 onto a display panel having a plurality of light-emitting elements arranged on one side of a substrate, and sealing the light-emitting elements using the adhesive layer; and The process of curing the adhesive layer by irradiating it with radiation.

13. The manufacturing method according to claim 12, wherein, The radiation is ultraviolet light.

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